Short-Term Grafting of Human Neural Stem Cells: Electrophysiological Properties and Motor Behavioral Amelioration in Experimental Parkinsons Disease.

PubMed

Martnez-Serrano, Alberto; Pereira, Marta P; Avaliani, Natalia; Nelke, Anna; Kokaia, Merab; Ramos-Moreno, Tania

2016-12-13

Cell replacement therapy in Parkinsons disease (PD) still lacks a study addressing the acquisition of electrophysiological properties of human grafted neural stem cells and their relation with the emergence of behavioral recovery after transplantation in the short term. Here we study the electrophysiological and biochemical profiles of two ventral mesencephalic human neural stem cell (NSC) clonal lines (C30-Bcl-XL and C32-Bcl-XL) that express high levels of Bcl-XL to enhance their neurogenic capacity, after grafting in an in vitro parkinsonian model. Electrophysiological recordings show that the majority of the cells derived from the transplants are not mature at 6 weeks after grafting, but 6.7% of the studied cells showed mature electrophysiological profiles. Nevertheless, parallel in vivo behavioral studies showed a significant motor improvement at 7 weeks postgrafting in the animals receiving C30-Bcl-XL, the cell line producing the highest amount of TH+ cells. Present results show that, at this postgrafting time point, behavioral amelioration highly correlates with the spatial dispersion of the TH+ grafted cells in the caudate putamen. The spatial dispersion, along with a high number of dopaminergic-derived cells, is crucial for behavioral improvements. Our findings have implications for long-term standardization of stem cell-based approaches in Parkinsons disease.

Viscoelastic properties of normal and cancerous human breast cells are affected differently by contact to adjacent cells.

PubMed

Schierbaum, Nicolas; Rheinlaender, Johannes; Schäffer, Tilman E

2017-06-01

Malignant transformation drastically alters the mechanical properties of the cell and its response to the surrounding cellular environment. We studied the influence of the physical contact between adjacent cells in an epithelial monolayer on the viscoelastic behavior of normal MCF10A, non-invasive cancerous MCF7, and invasive cancerous MDA-MB-231 human breast cells. Using an atomic force microscopy (AFM) imaging technique termed force clamp force mapping (FCFM) to record images of the viscoelastic material properties, we found that normal MCF10A cells are stiffer and have a lower fluidity at confluent than at sparse density. Contrarily, cancerous MCF7 and MDA-MB-231 cells do not stiffen and do not decrease their fluidity when progressing from sparse to confluent density. The behavior of normal MCF10A cells appears to be governed by the formation of stable cell-cell contacts, because their disruption with a calcium-chelator (EGTA) causes the stiffness and fluidity values to return to those at sparse density. In contrast, EGTA-treatment of MCF7 and MDA-MB-231 cells does not change their viscoelastic properties. Confocal fluorescence microscopy showed that the change of the viscoelastic behavior in MCF10A cells when going from sparse to confluent density is accompanied by a remodeling of the actin cytoskeleton into thick stress fiber bundles, while in MCF7 and MDA-MB-231 cells the actin cytoskeleton is only composed of thin and short fibers, regardless of cell density. While the observed behavior of normal MCF10A cells might be crucial for providing mechanical stability and thus in turn integrity of the epithelial monolayer, the dysregulation of this behavior in cancerous MCF7 and MDA-MB-231 cells is possibly a central aspect of cancer progression in the epithelium. We measured the viscoelastic properties of normal and cancerous human breast epithelial cells in different states of confluency using atomic force microscopy. We found that confluent normal cells are stiffer and have lower fluidity than sparse normal cells, which appears to be governed by the formation of cell-cell contacts. Contrarily, confluent cancer cells do not stiffen and not have a decreased fluidity compared to sparse cancer cells and their viscoelastic properties are independent of cell-cell contact formation. While the observed behavior of normal cells appears to be crucial for providing the mechanical stability and therefore the integrity of the epithelial monolayer, the dysregulation of this behavior in cancer cells might be a central aspect of early stage cancer progression and metastasis in the epithelium. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Gravin regulates mesodermal cell behavior changes required for axis elongation during zebrafish gastrulation.

PubMed

Weiser, Douglas C; Pyati, Ujwal J; Kimelman, David

2007-06-15

Convergent extension of the mesoderm is the major driving force of vertebrate gastrulation. During this process, mesodermal cells move toward the future dorsal side of the embryo, then radically change behavior as they initiate extension of the body axis. How cells make this transition in behavior is unknown. We have identified the scaffolding protein and tumor suppressor Gravin as a key regulator of this process in zebrafish embryos. We show that Gravin is required for the conversion of mesodermal cells from a highly migratory behavior to the medio-laterally intercalative behavior required for body axis extension. In the absence of Gravin, paraxial mesodermal cells fail to shut down the protrusive activity mediated by the Rho/ROCK/Myosin II pathway, resulting in embryos with severe extension defects. We propose that Gravin functions as an essential scaffold for regulatory proteins that suppress the migratory behavior of the mesoderm during gastrulation, and suggest that this function also explains how Gravin inhibits invasive behaviors in metastatic cells.

Improved light-induced cell detachment on rutile TiO₂ nanodot films.

PubMed

Cheng, Kui; Sun, Yu; Wan, Hongping; Wang, Xiaozhao; Weng, Wenjian; Lin, Jun; Wang, Huiming

2015-10-01

Anatase TiO2 nanodot films have been found to be able to release cells under light illumination with excellent efficiency and safety. In the present study, we investigated the effects of rutile contents in TiO2 nanodot films on such light induced cell detachment behavior. The results showed that TiO2 nanodot films with different contents of rutile phase have been prepared successfully. The content of rutile phase increased with the increase in calcination temperature. All films possessed good cell adhesion but there was a decrease in cell proliferation with the increasing content of rutile phase. Single cell detachment assay showed that the films with high rutile contents (calcined at 900°C and 1100°C) showed better cell detachment performance. That was ascribed to the changes of the secondary structure of extracellular proteins adsorbed on the nanodot surface after ultraviolet (365 nm, UV365) illumination. In addition, cell sheets detached through UV365 illumination maintained high activity and could be further used in tissue engineering. The present work showed that the existence of rutile phase is helpful in cell detachment behavior and it could be utilized to optimize light-induced cell detachment behavior. This work discovers that the presence of rutile phase in TiO2 nanodot films could improve the light-induced cell detachment behavior, although rutile phase is inferior to anatase phase on light induced superhydrophilicity. That strongly supported that the behaviors of adsorbed proteins are crucial in acquiring cell sheet with light illumination. In fact, the state and behavior of adsorbed protein greatly affect the interaction between biomaterials and living cells. Therefore, we consider this work is not only important in harvesting cells or cell sheets through light illumination, but also helpful in further understanding of interaction between biomaterials and cells. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Planar cell polarity in moving cells: think globally, act locally

PubMed Central

Davey, Crystal F.

2017-01-01

ABSTRACT The planar cell polarity (PCP) pathway is best known for its role in polarizing epithelial cells within the plane of a tissue but it also plays a role in a range of cell migration events during development. The mechanism by which the PCP pathway polarizes stationary epithelial cells is well characterized, but how PCP signaling functions to regulate more dynamic cell behaviors during directed cell migration is much less understood. Here, we review recent discoveries regarding the localization of PCP proteins in migrating cells and their impact on the cell biology of collective and individual cell migratory behaviors. PMID:28096212

Inflammatory Th17 cells promote depression-like behavior in mice

PubMed Central

Beurel, Eléonore; Harrington, Laurie E.; Jope, Richard S.

2012-01-01

Background Recognition of substantial immune-neural interactions is revising dogmas about their insular actions and revealing that immune-neural interactions can substantially impact CNS functions. The inflammatory cytokine interleukin-6 promotes susceptibility to depression and drives production of inflammatory T helper 17 (Th17) T cells, raising the hypothesis that in mouse models Th17 cells promote susceptibility to depression-like behaviors. Methods Behavioral characteristics were measured in male mice administered Th17 cells, CD4+ cells, or vehicle, and in RORγT+/GFP mice or male mice treated with RORγT inhibitor or anti-IL-17A antibodies. Results Mouse brain Th17 cells were elevated by learned helplessness and chronic restraint stress, two common depression-like models. Th17 cell administration promoted learned helplessness in 89% of mice in a paradigm where no vehicle-treated mice developed learned helplessness, and impaired novelty suppressed feeding and social interaction behaviors. Mice deficient in the RORγT transcription factor necessary for Th17 cell production exhibited resistance to learned helplessness, identifying modulation of RORγT as a potential intervention. Treatment with the RORγT inhibitor SR1001, or anti-IL-17A antibodies to abrogate Th17 cell function, reduced Th17-dependent learned helplessness. Conclusions These findings indicate that Th17 cells are increased in the brain during depression-like states, promote depression-like behaviors in mice, and specifically inhibiting the production or function of Th17 cells reduces vulnerability to depression-like behavior, suggesting antidepressant effects may be attained by targeting Th17 cells. PMID:23174342

Connecting single cell to collective cell behavior in a unified theoretical framework

NASA Astrophysics Data System (ADS)

George, Mishel; Bullo, Francesco; Campàs, Otger

Collective cell behavior is an essential part of tissue and organ morphogenesis during embryonic development, as well as of various disease processes, such as cancer. In contrast to many in vitro studies of collective cell migration, most cases of in vivo collective cell migration involve rather small groups of cells, with large sheets of migrating cells being less common. The vast majority of theoretical descriptions of collective cell behavior focus on large numbers of cells, but fail to accurately capture the dynamics of small groups of cells. Here we introduce a low-dimensional theoretical description that successfully captures single cell migration, cell collisions, collective dynamics in small groups of cells, and force propagation during sheet expansion, all within a common theoretical framework. Our description is derived from first principles and also includes key phenomenological aspects of cell migration that control the dynamics of traction forces. Among other results, we explain the counter-intuitive observations that pairs of cells repel each other upon collision while they behave in a coordinated manner within larger clusters.

Electrical stimulation as a biomimicry tool for regulating muscle cell behavior

PubMed Central

Ahadian, Samad; Ostrovidov, Serge; Hosseini, Vahid; Kaji, Hirokazu; Ramalingam, Murugan; Bae, Hojae; Khademhosseini, Ali

2013-01-01

There is a growing need to understand muscle cell behaviors and to engineer muscle tissues to replace defective tissues in the body. Despite a long history of the clinical use of electric fields for muscle tissues in vivo, electrical stimulation (ES) has recently gained significant attention as a powerful tool for regulating muscle cell behaviors in vitro. ES aims to mimic the electrical environment of electroactive muscle cells (e.g., cardiac or skeletal muscle cells) by helping to regulate cell-cell and cell-extracellular matrix (ECM) interactions. As a result, it can be used to enhance the alignment and differentiation of skeletal or cardiac muscle cells and to aid in engineering of functional muscle tissues. Additionally, ES can be used to control and monitor force generation and electrophysiological activity of muscle tissues for bio-actuation and drug-screening applications in a simple, high-throughput, and reproducible manner. In this review paper, we briefly describe the importance of ES in regulating muscle cell behaviors in vitro, as well as the major challenges and prospective potential associated with ES in the context of muscle tissue engineering. PMID:23823664

Electrical stimulation as a biomimicry tool for regulating muscle cell behavior.

PubMed

Ahadian, Samad; Ostrovidov, Serge; Hosseini, Vahid; Kaji, Hirokazu; Ramalingam, Murugan; Bae, Hojae; Khademhosseini, Ali

2013-01-01

There is a growing need to understand muscle cell behaviors and to engineer muscle tissues to replace defective tissues in the body. Despite a long history of the clinical use of electric fields for muscle tissues in vivo, electrical stimulation (ES) has recently gained significant attention as a powerful tool for regulating muscle cell behaviors in vitro. ES aims to mimic the electrical environment of electroactive muscle cells (e.g., cardiac or skeletal muscle cells) by helping to regulate cell-cell and cell-extracellular matrix (ECM) interactions. As a result, it can be used to enhance the alignment and differentiation of skeletal or cardiac muscle cells and to aid in engineering of functional muscle tissues. Additionally, ES can be used to control and monitor force generation and electrophysiological activity of muscle tissues for bio-actuation and drug-screening applications in a simple, high-throughput, and reproducible manner. In this review paper, we briefly describe the importance of ES in regulating muscle cell behaviors in vitro, as well as the major challenges and prospective potential associated with ES in the context of muscle tissue engineering.

Dynamic Manipulation of Hydrogels to Control Cell Behavior: A Review

PubMed Central

Vats, Kanika

2013-01-01

For many tissue engineering applications and studies to understand how materials fundamentally affect cellular functions, it is important to have the ability to synthesize biomaterials that can mimic elements of native cell–extracellular matrix interactions. Hydrogels possess many properties that are desirable for studying cell behavior. For example, hydrogels are biocompatible and can be biochemically and mechanically altered by exploiting the presentation of cell adhesive epitopes or by changing hydrogel crosslinking density. To establish physical and biochemical tunability, hydrogels can be engineered to alter their properties upon interaction with external driving forces such as pH, temperature, electric current, as well as exposure to cytocompatible irradiation. Additionally, hydrogels can be engineered to respond to enzymes secreted by cells, such as matrix metalloproteinases and hyaluronidases. This review details different strategies and mechanisms by which biomaterials, specifically hydrogels, can be manipulated dynamically to affect cell behavior. By employing the appropriate combination of stimuli and hydrogel composition and architecture, cell behavior such as adhesion, migration, proliferation, and differentiation can be controlled in real time. This three-dimensional control in cell behavior can help create programmable cell niches that can be useful for fundamental cell studies and in a variety of tissue engineering applications. PMID:23541134

Topography and behavior of Sertoli cells in sparse culture during the transitional remodeling phase.

PubMed

Tung, P S; Choi, A H; Fritz, I B

1988-01-01

We report observations on the behavior of Sertoli cells in sparse culture during the period from the time of plating to the time of initial confluence (the transitional remodeling phase). Changes in shape, structure, and polarity of cells, as well as changes in migration patterns and cell-cell association patterns, have been followed during the transitional remodeling phase with the aid of topographical markers. These markers are based upon differences between ultrastructural features of the basolateral and apicolateral surfaces. The basolateral surface is characterized by plasmalemmal blebs, whereas the apicolateral surface is characterized by filopodial extensions. Structural differences observed in situ remain evident in Sertoli cells isolated by sequential enzymatic treatments that are described. Another marker is provided by laminin-binding sites, which are detected exclusively on the blebbed, basolateral surfaces of freshly prepared Sertoli cell aggregates. The orientation described is sustained during the initial radial migration of Sertoli cells explanted on uncoated glass coverslips. Under these conditions, blebs are detected only on the dorsal surfaces, and filopodial extensions are evident only on the ventral surfaces. In contrast, Sertoli cells sparsely plated on a reconstituted basement membrane (air-dried Matrigel) migrate rapidly, display an extraordinary capacity to form elaborate cytoplasmic extensions for cell-cell and cell-substratum contacts, and readily retract blebs and filopodial extensions. These cells do not form mosaic borders, whereas cells plated on uncoated glass do form a monolayer with mosaic-like borders. Cells sparsely seeded on gelated Matrigel migrate preferentially at gaps between adjacent cell explants, and develop a compact cell-cell association pattern. These cells display few, if any, cytoplasmic extensions. We compare the behavior of Sertoli cells sparsely plated on Matrigel with the behavior of Sertoli cells in situ during different stages of development.

Engineering artificial cells by combining HeLa-based cell-free expression and ultra-thin double emulsion template

PubMed Central

Ho, Kwun Yin; Murray, Victoria L.; Liu, Allen P.

2015-01-01

Generation of artificial cells provides the bridge needed to cover the gap between studying the complexity of biological processes in whole cells and studying these same processes in an in vitro reconstituted system. Artificial cells are defined as the encapsulation of biologically active material in a biological or synthetic membrane. Here, we describe a robust and general method to produce artificial cells for the purpose of mimicking one or more behaviors of a cell. A microfluidic double emulsion system is used to encapsulate a mammalian cell free expression system that is able to express membrane proteins into the bilayer or soluble proteins inside the vesicles. The development of a robust platform that allows the assembly of artificial cells is valuable in understanding subcellular functions and emergent behaviors in a more cell-like environment as well as for creating novel signaling pathways to achieve specific cellular behaviors. PMID:25997354

Nanotechnology in the regulation of stem cell behavior

NASA Astrophysics Data System (ADS)

Wu, King-Chuen; Tseng, Ching-Li; Wu, Chi-Chang; Kao, Feng-Chen; Tu, Yuan-Kun; So, Edmund C.; Wang, Yang-Kao

2013-10-01

Stem cells are known for their potential to repair damaged tissues. The adhesion, growth and differentiation of stem cells are likely controlled by the surrounding microenvironment which contains both chemical and physical cues. Physical cues in the microenvironment, for example, nanotopography, were shown to play important roles in stem cell fate decisions. Thus, controlling stem cell behavior by nanoscale topography has become an important issue in stem cell biology. Nanotechnology has emerged as a new exciting field and research from this field has greatly advanced. Nanotechnology allows the manipulation of sophisticated surfaces/scaffolds which can mimic the cellular environment for regulating cellular behaviors. Thus, we summarize recent studies on nanotechnology with applications to stem cell biology, including the regulation of stem cell adhesion, growth, differentiation, tracking and imaging. Understanding the interactions of nanomaterials with stem cells may provide the knowledge to apply to cell-scaffold combinations in tissue engineering and regenerative medicine.

A simple and accurate rule-based modeling framework for simulation of autocrine/paracrine stimulation of glioblastoma cell motility and proliferation by L1CAM in 2-D culture.

PubMed

Caccavale, Justin; Fiumara, David; Stapf, Michael; Sweitzer, Liedeke; Anderson, Hannah J; Gorky, Jonathan; Dhurjati, Prasad; Galileo, Deni S

2017-12-11

Glioblastoma multiforme (GBM) is a devastating brain cancer for which there is no known cure. Its malignancy is due to rapid cell division along with high motility and invasiveness of cells into the brain tissue. Simple 2-dimensional laboratory assays (e.g., a scratch assay) commonly are used to measure the effects of various experimental perturbations, such as treatment with chemical inhibitors. Several mathematical models have been developed to aid the understanding of the motile behavior and proliferation of GBM cells. However, many are mathematically complicated, look at multiple interdependent phenomena, and/or use modeling software not freely available to the research community. These attributes make the adoption of models and simulations of even simple 2-dimensional cell behavior an uncommon practice by cancer cell biologists. Herein, we developed an accurate, yet simple, rule-based modeling framework to describe the in vitro behavior of GBM cells that are stimulated by the L1CAM protein using freely available NetLogo software. In our model L1CAM is released by cells to act through two cell surface receptors and a point of signaling convergence to increase cell motility and proliferation. A simple graphical interface is provided so that changes can be made easily to several parameters controlling cell behavior, and behavior of the cells is viewed both pictorially and with dedicated graphs. We fully describe the hierarchical rule-based modeling framework, show simulation results under several settings, describe the accuracy compared to experimental data, and discuss the potential usefulness for predicting future experimental outcomes and for use as a teaching tool for cell biology students. It is concluded that this simple modeling framework and its simulations accurately reflect much of the GBM cell motility behavior observed experimentally in vitro in the laboratory. Our framework can be modified easily to suit the needs of investigators interested in other similar intrinsic or extrinsic stimuli that influence cancer or other cell behavior. This modeling framework of a commonly used experimental motility assay (scratch assay) should be useful to both researchers of cell motility and students in a cell biology teaching laboratory.

Inflammatory T helper 17 cells promote depression-like behavior in mice.

PubMed

Beurel, Eléonore; Harrington, Laurie E; Jope, Richard S

2013-04-01

Recognition of substantial immune-neural interactions is revising dogmas about their insular actions and revealing that immune-neural interactions can substantially impact central nervous system functions. The inflammatory cytokine interleukin-6 promotes susceptibility to depression and drives production of inflammatory T helper 17 (Th17) T cells, raising the hypothesis that in mouse models, Th17 cells promote susceptibility to depression-like behaviors. Behavioral characteristics were measured in male mice administered Th17 cells, CD4(+) cells, or vehicle and in retinoid-related orphan receptor-γT (RORγT)(+/GFP) mice or male mice treated with RORγT inhibitor or anti-interleukin-17A antibodies. Mouse brain Th17 cells were elevated by learned helplessness and chronic restraint stress, two common depression-like models. Th17 cell administration promoted learned helplessness in 89% of mice in a paradigm where no vehicle-treated mice developed learned helplessness, and impaired novelty suppressed feeding and social interaction behaviors. Mice deficient in the RORγT transcription factor necessary for Th17 cell production exhibited resistance to learned helplessness, identifying modulation of RORγT as a potential intervention. Treatment with the RORγT inhibitor SR1001, or anti-interleukin-17A antibodies to abrogate Th17 cell function, reduced Th17-dependent learned helplessness. These findings indicate that Th17 cells are increased in the brain during depression-like states, promote depression-like behaviors in mice, and specifically inhibiting the production or function of Th17 cells reduces vulnerability to depression-like behavior, suggesting antidepressant effects may be attained by targeting Th17 cells. Copyright © 2013 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Dynamical mechanism of circadian singularity behavior in Neurospora

NASA Astrophysics Data System (ADS)

Sun, Maorong; Wang, Yi; Xu, Xin; Yang, Ling

2016-09-01

Many organisms have oscillators with a period of about 24 hours, called "circadian clocks". They employ negative biochemical feedback loops that are self-contained within a single cell (requiring no cell-to-cell interaction). Circadian singularity behavior is a phenomenon of the abolishment of circadian rhythmicities by a critical stimulus. These behaviors have been found experimentally in Neurospora, human and hamster, by temperature step-up or light pulse. Two alternative models have been proposed to explain this phenomenon: desynchronization of cell populations, and loss of oscillations in all cells by resetting each cell close to a steady state. In this work, we use a mathematical model to investigate the dynamical mechanism of circadian singularity behavior in Neurospora. Our findings suggest that the arrhythmic behavior after the critical stimulus is caused by the collaboration of the desynchronization and the loss of oscillation amplitude. More importantly, we found that the stable manifold of the unstable equilibrium point, instead of the steady state itself, plays a crucial role in circadian singularity behavior.

Maternal cell phone use during pregnancy and child behavioral problems in five birth cohorts.

PubMed

Birks, Laura; Guxens, Mònica; Papadopoulou, Eleni; Alexander, Jan; Ballester, Ferran; Estarlich, Marisa; Gallastegi, Mara; Ha, Mina; Haugen, Margaretha; Huss, Anke; Kheifets, Leeka; Lim, Hyungryul; Olsen, Jørn; Santa-Marina, Loreto; Sudan, Madhuri; Vermeulen, Roel; Vrijkotte, Tanja; Cardis, Elisabeth; Vrijheid, Martine

2017-07-01

Previous studies have reported associations between prenatal cell phone use and child behavioral problems, but findings have been inconsistent and based on retrospective assessment of cell phone use. This study aimed to assess this association in a multi-national analysis, using data from three cohorts with prospective data on prenatal cell phone use, together with previously published data from two cohorts with retrospectively collected cell phone use data. We used individual participant data from 83,884 mother-child pairs in the five cohorts from Denmark (1996-2002), Korea (2006-2011), the Netherlands (2003-2004), Norway (2004-2008), and Spain (2003-2008). We categorized cell phone use into none, low, medium, and high, based on frequency of calls during pregnancy reported by the mothers. Child behavioral problems (reported by mothers using the Strengths and Difficulties Questionnaire or Child Behavior Checklist) were classified in the borderline/clinical and clinical ranges using validated cut-offs in children aged 5-7years. Cohort specific risk estimates were meta-analyzed. Overall, 38.8% of mothers, mostly from the Danish cohort, reported no cell phone use during pregnancy and these mothers were less likely to have a child with overall behavioral, hyperactivity/inattention or emotional problems. Evidence for a trend of increasing risk of child behavioral problems through the maternal cell phone use categories was observed for hyperactivity/inattention problems (OR for problems in the clinical range: 1.11, 95%CI 1.01, 1.22; 1.28, 95%CI 1.12, 1.48, among children of medium and high users, respectively). This association was fairly consistent across cohorts and between cohorts with retrospectively and prospectively collected cell phone use data. Maternal cell phone use during pregnancy may be associated with an increased risk for behavioral problems, particularly hyperactivity/inattention problems, in the offspring. The interpretation of these results is unclear as uncontrolled confounding may influence both maternal cell phone use and child behavioral problems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Species-independent attraction to biofilms through electrical signaling

PubMed Central

Humphries, Jacqueline; Xiong, Liyang; Liu, Jintao; Prindle, Arthur; Yuan, Fang; Arjes, Heidi A.; Tsimring, Lev; Süel, Gürol M.

2017-01-01

Summary Bacteria residing within biofilm communities can coordinate their behavior through cell-to-cell signaling. However, it remains unclear if these signals can also influence the behavior of distant cells that are not part of the community. Using a microfluidic approach, we find that potassium ion channel-mediated electrical signaling generated by a Bacillus subtilis biofilm can attract distant cells. Integration of experiments and mathematical modeling indicates that extracellular potassium emitted from the biofilm alters the membrane potential of distant cells, thereby directing their motility. This electrically-mediated attraction appears to be a generic mechanism that enables cross-species interactions, as Pseudomonas aeruginosa cells also become attracted to the electrical signal released by the B. subtilis biofilm. Cells within a biofilm community can thus not only coordinate their own behavior, but also influence the behavior of diverse bacteria at a distance through long-range electrical signaling. PMID:28086091

Modeling mechanical interactions in growing populations of rod-shaped bacteria

NASA Astrophysics Data System (ADS)

Winkle, James J.; Igoshin, Oleg A.; Bennett, Matthew R.; Josić, Krešimir; Ott, William

2017-10-01

Advances in synthetic biology allow us to engineer bacterial collectives with pre-specified characteristics. However, the behavior of these collectives is difficult to understand, as cellular growth and division as well as extra-cellular fluid flow lead to complex, changing arrangements of cells within the population. To rationally engineer and control the behavior of cell collectives we need theoretical and computational tools to understand their emergent spatiotemporal dynamics. Here, we present an agent-based model that allows growing cells to detect and respond to mechanical interactions. Crucially, our model couples the dynamics of cell growth to the cell’s environment: Mechanical constraints can affect cellular growth rate and a cell may alter its behavior in response to these constraints. This coupling links the mechanical forces that influence cell growth and emergent behaviors in cell assemblies. We illustrate our approach by showing how mechanical interactions can impact the dynamics of bacterial collectives growing in microfluidic traps.

Behavior-dependent specialization of identified hippocampal interneurons

PubMed Central

Lapray, Damien; Lasztoczi, Balint; Lagler, Michael; Viney, Tim James; Katona, Linda; Valenti, Ornella; Hartwich, Katja; Borhegyi, Zsolt; Somogyi, Peter; Klausberger, Thomas

2012-01-01

A large variety of GABAergic interneurons control information processing in hippocampal circuits governing the formation of neuronal representations. Whether distinct hippocampal interneuron types contribute differentially to information-processing during behavior is not known. We employed a novel technique for recording and labeling interneurons and pyramidal cells in drug-free, freely-moving rats. Recorded parvalbumin-expressing basket interneurons innervate somata and proximal pyramidal cell dendrites, whereas nitric-oxide-synthase- and neuropeptide-Y-expressing ivy cells provide synaptic and extrasynaptic dendritic modulation. Basket and ivy cells showed distinct spike timing dynamics, firing at different rates and times during theta and ripple oscillations. Basket but not ivy cells changed their firing rates during movement, sleep and quiet wakefulness, suggesting that basket cells coordinate cell assemblies in a behavioral state-contingent manner, whereas persistently-firing ivy cells might control network excitability and homeostasis. Different interneuron types provide GABA to specific subcellular domains at defined times and rates, thus differentially controlling network activity during behavior. PMID:22864613

Morphological adaptations in breast cancer cells as a function of prolonged passaging on compliant substrates

PubMed Central

Syed, Sana; Schober, Joseph; Blanco, Alexandra

2017-01-01

Standard tissue culture practices involve propagating cells on tissue culture polystyrene (TCP) dishes, which are flat, 2-dimensional (2D) and orders of magnitude stiffer than most tissues in the body. Such simplified conditions lead to phenotypical cell changes and altered cell behaviors. Hence, much research has been focused on developing novel biomaterials and culture conditions that more closely emulate in vivo cell microenvironments. In particular, biomaterial stiffness has emerged as a key property that greatly affects cell behaviors such as adhesion, morphology, proliferation and motility among others. Here we ask whether cells that have been conditioned to TCP, would still show significant dependence on substrate stiffness if they are first pre-adapted to a more physiologically relevant environment. We used two commonly utilized breast cancer cell lines, namely MDA-MB-231 and MCF-7, and examined the effect of prolonged cell culturing on polyacrylamide substrates of varying compliance. We followed changes in cell adhesion, proliferation, shape factor, spreading area and spreading rate. After pre-adaptation, we noted diminished differences in cell behaviors when comparing between soft (1 kPa) and stiff (103 kPa) gels as well as rigid TCP control. Prolonged culturing of cells on complaint substrates further influenced responses of pre-adapted cells when transferred back to TCP. Our results have implications for the study of stiffness-dependent cell behaviors and indicate that cell pre-adaptation to the substrate needs consideration. PMID:29136040

Cyclic adenosine monophosphate modulates cell morphology and behavior of a cultured renal epithelial.

PubMed

Amsler, K

1990-07-01

The role of cyclic adenosine monophosphate (cAMP) dependent protein kinase (PKA) in modulating functions of differentiated renal cells is well established. Its importance in controlling their growth and differentiation is less clear. We have used somatic cell genetic techniques to probe the role of PKA in controlling morphology and behavior of a renal epithelial cell line, LLC-PK1, which acquires many properties characteristic of the renal proximal tubular cell. Mutants of this line altered in PKA activity have been isolated and their behavior compared to that of the parent line. The results indicate that PKA is involved, either directly or indirectly, in maintenance of cell morphology, cell-cell and cell-substratum interactions, density-dependent growth regulation, and expression of one function characteristic of the renal proximal tubular cell, Na-hexose symport. The relevance of these results to the role of PKA in controlling growth and differentiation of renal epithelial cells in vivo is discussed.

Investigation of the hydrodynamic response of cells in drop on demand piezoelectric inkjet nozzles.

PubMed

Cheng, Eric; Yu, Haoran; Ahmadi, Ali; Cheung, Karen C

2016-01-29

Cell motion within a liquid suspension inside a piezoelectrically actuated, cylindrical inkjet printhead was studied using high speed imaging and a low depth of field setup. For each ejected droplet, a cell within the inkjet nozzle was observed to exhibit one of three possible behaviors which are termed: cell travel, cell ejection and cell reflection. Cell reflection is an undesirable phenomenon which may adversely affect an inkjet's capability in dispensing cells and a possible reason why it was previously reported that the rate of cells dispensed did not follow the expected Poisson distribution. Through the study of the cells motions, it was hypothesized that the rheological properties of the media in the cell suspension play an important role in influencing the cell behaviors exhibited. This was experimentally studied with the tracking of cells within the inkjet nozzle in a 10% w/v Ficoll PM400 cell suspension. The effect of cell reflection was eliminated using the higher density and viscosity Ficoll PM400 suspension. The presented work is the first in-depth study of the cell behaviors occurring within a piezoelectric inkjet nozzle during the printing process. The understanding of the hydrodynamics during a droplet ejection and its effect on the suspended cells are imperative towards achieving reliable cell dispensing for biofabrication applications.

Jamming and liquidity in 3D cancer cell aggregates

NASA Astrophysics Data System (ADS)

Oswald, Linda; Grosser, Steffen; Lippoldt, Jürgen; Pawlizak, Steve; Fritsch, Anatol; KäS, Josef A.

Traditionally, tissues are treated as simple liquids, which holds for example for embryonic tissue. However, recent experiments have shown that this picture is insufficient for other tissue types, suggesting possible transitions to solid-like behavior induced by cellular jamming. The coarse-grained self-propelled Voronoi (SPV) model predicts such a transition depending on cell shape which is thought to arise from an interplay of cell-cell adhesion and cortical tension. We observe non-liquid behavior in 3D breast cancer spheroids of varying metastatic potential and correlate single cell shapes, single cell dynamics and collective dynamic behavior of fusion and segregation experiments via the SPV model.

Dynamic phase differences based on quantitative phase imaging for the objective evaluation of cell behavior.

PubMed

Krizova, Aneta; Collakova, Jana; Dostal, Zbynek; Kvasnica, Lukas; Uhlirova, Hana; Zikmund, Tomas; Vesely, Pavel; Chmelik, Radim

2015-01-01

Quantitative phase imaging (QPI) brought innovation to noninvasive observation of live cell dynamics seen as cell behavior. Unlike the Zernike phase contrast or differential interference contrast, QPI provides quantitative information about cell dry mass distribution. We used such data for objective evaluation of live cell behavioral dynamics by the advanced method of dynamic phase differences (DPDs). The DPDs method is considered a rational instrument offered by QPI. By subtracting the antecedent from the subsequent image in a time-lapse series, only the changes in mass distribution in the cell are detected. The result is either visualized as a two dimensional color-coded projection of these two states of the cell or as a time dependence of changes quantified in picograms. Then in a series of time-lapse recordings, the chain of cell mass distribution changes that would otherwise escape attention is revealed. Consequently, new salient features of live cell behavior should emerge. Construction of the DPDs method and results exhibiting the approach are presented. Advantage of the DPDs application is demonstrated on cells exposed to an osmotic challenge. For time-lapse acquisition of quantitative phase images, the recently developed coherence-controlled holographic microscope was employed.

Dynamic phase differences based on quantitative phase imaging for the objective evaluation of cell behavior

NASA Astrophysics Data System (ADS)

Krizova, Aneta; Collakova, Jana; Dostal, Zbynek; Kvasnica, Lukas; Uhlirova, Hana; Zikmund, Tomas; Vesely, Pavel; Chmelik, Radim

2015-11-01

Quantitative phase imaging (QPI) brought innovation to noninvasive observation of live cell dynamics seen as cell behavior. Unlike the Zernike phase contrast or differential interference contrast, QPI provides quantitative information about cell dry mass distribution. We used such data for objective evaluation of live cell behavioral dynamics by the advanced method of dynamic phase differences (DPDs). The DPDs method is considered a rational instrument offered by QPI. By subtracting the antecedent from the subsequent image in a time-lapse series, only the changes in mass distribution in the cell are detected. The result is either visualized as a two-dimensional color-coded projection of these two states of the cell or as a time dependence of changes quantified in picograms. Then in a series of time-lapse recordings, the chain of cell mass distribution changes that would otherwise escape attention is revealed. Consequently, new salient features of live cell behavior should emerge. Construction of the DPDs method and results exhibiting the approach are presented. Advantage of the DPDs application is demonstrated on cells exposed to an osmotic challenge. For time-lapse acquisition of quantitative phase images, the recently developed coherence-controlled holographic microscope was employed.

Children with Sickle-Cell Anemia: Parental Relations, Parent-Child Relations, and Child Behavior.

ERIC Educational Resources Information Center

Evans, Robert C.; And Others

1988-01-01

Investigated the influence of a child with sickle-cell anemia on parental affiliation, parent-child relationships, and parents' perception of their child's behavior. In the sickle-cell group, parents' interpersonal relationship suffered; parent-child relationship and child behavior correlated significantly; and single-parent families estimated…

Cell Phone-Based Expert Systems for Smoking Cessation

DTIC Science & Technology

2011-09-01

computerized tailored intervention (CTI) with feedback messages delivered via cell phone . CTIs have shown increasing promise as useful behavior change programs...behaviors. This will be the first study to adapt a smoking cessation Internet-based CTI to provide personalized feedback on a cell phone to reduce smoking behaviors in military veterans.

Self-reported and observed risky driving behaviors among frequent and infrequent cell phone users.

PubMed

Zhao, Nan; Reimer, Bryan; Mehler, Bruce; D'Ambrosio, Lisa A; Coughlin, Joseph F

2013-12-01

The apparently higher crash risk among individuals who use cell phones while driving may be due both to the direct interference of cell phone use with the driving task and tendencies to engage in risky driving behaviors independent of cell phone use. Measurements of actual highway driving performance, self-reported aberrant driving behaviors as measured by the Manchester Driver Behavior Questionnaire (DBQ), and attitudes toward speeding, passing behaviors and relative concern about being involved in a crash were assessed. Individuals who reported frequently using cell phones while driving were found to drive faster, change lanes more frequently, spend more time in the left lane, and engage in more instances of hard braking and high acceleration events. They also scored higher in self-reported driving violations on the DBQ and reported more positive attitudes toward speeding and passing than drivers who did not report using a cell phone regularly while driving. These results indicate that a greater reported frequency of cell phone use while driving is associated with a broader pattern of behaviors that are likely to increase the overall risk of crash involvement. Copyright © 2012 Elsevier Ltd. All rights reserved.

CD11c-expressing cells affect Treg behavior in the meninges during CNS infection1

PubMed Central

O’Brien, Carleigh A.; Overall, Christopher; Konradt, Christoph; O’Hara Hall, Aisling C.; Hayes, Nikolas W.; Wagage, Sagie; John, Beena; Christian, David A.; Hunter, Christopher A.; Harris, Tajie H.

2017-01-01

Treg cells play an important role in the CNS during multiple infections as well as autoimmune inflammation, but the behavior of this cell type in the CNS has not been explored. In mice, infection with Toxoplasma gondii leads to a Th1-polarized parasite-specific effector T cell response in the brain. Similarly, the Treg cells in the CNS during T. gondii infection are Th1-polarized, exemplified by T-bet, CXCR3, and IFN-γ expression. Unlike effector CD4+ T cells, an MHC Class II tetramer reagent specific for T. gondii did not recognize Treg cells isolated from the CNS. Likewise, TCR sequencing revealed minimal overlap in TCR sequence between effector and regulatory T cells in the CNS. Whereas effector T cells are found in the brain parenchyma where parasites are present, Treg cells were restricted to the meninges and perivascular spaces. The use of intravital imaging revealed that activated CD4+ T cells within the meninges were highly migratory, while Treg cells moved more slowly and were found in close association with CD11c+ cells. To test whether the behavior of Tregs in the meninges is influenced by interactions with CD11c+ cells, mice were treated with anti-LFA-1 antibodies to reduce the number of CD11c+ cells in this space. The anti-LFA-1 treatment led to fewer contacts between Tregs and the remaining CD11c+ cells and increased the speed of Treg cell migration. These data suggest that Treg cells are anatomically restricted within the CNS and the interaction with CD11c+ populations regulates their local behavior during T. gondii infection. PMID:28389591

Species differences in behavior and cell proliferation/survival in the adult brains of female meadow and prairie voles

PubMed Central

Pan, Yongliang; Liu, Yan; Lieberwirth, Claudia; Zhang, Zhibin; Wang, Zuoxin

2016-01-01

Microtine rodents display diverse patterns of social organization and behaviors, and thus provide a useful model for studying the effects of the social environment on physiology and behavior. The current study compared the species differences and the effects of oxytocin (OT) on anxiety-like, social affiliation, and social recognition behaviors in female meadow voles (Microtus pennsylvanicus) and prairie voles (M. ochrogaster). Furthermore, cell proliferation and survival in the brains of adult female meadow and prairie voles were compared. We found that female meadow voles displayed a higher level of anxiety-like behavior but lower levels of social affiliation and social recognition compared to female prairie voles. In addition, meadow voles showed lower levels of cell proliferation (measured by Ki67 staining) and cell survival (measured by BrdU staining) in the ventromedial hypothalamus (VMH) and amygdala (AMY), but not the dentate gyrus of the hippocampus (DG), than prairie voles. Interestingly, the numbers of new cells in the VMH and AMY, but not DG, also correlated with anxiety-like, social affiliation, and social recognition behaviors in a brain region-specific manner. Finally, central OT treatment (200 ng/kg, icv) did not lead to changes in behavior or cell proliferation/survival in the brain. Together, these data indicate a potential role of cell proliferation/survival in selected brain areas on different behaviors between vole species with distinct life strategies. PMID:26708743

Emergent cell and tissue dynamics from subcellular modeling of active biomechanical processes

NASA Astrophysics Data System (ADS)

Sandersius, S. A.; Weijer, C. J.; Newman, T. J.

2011-08-01

Cells and the tissues they form are not passive material bodies. Cells change their behavior in response to external biochemical and biomechanical cues. Behavioral changes, such as morphological deformation, proliferation and migration, are striking in many multicellular processes such as morphogenesis, wound healing and cancer progression. Cell-based modeling of these phenomena requires algorithms that can capture active cell behavior and their emergent tissue-level phenotypes. In this paper, we report on extensions of the subcellular element model to model active biomechanical subcellular processes. These processes lead to emergent cell and tissue level phenotypes at larger scales, including (i) adaptive shape deformations in cells responding to slow stretching, (ii) viscous flow of embryonic tissues, and (iii) streaming patterns of chemotactic cells in epithelial-like sheets. In each case, we connect our simulation results to recent experiments.

Uncovering cancer cell behavioral phenotype in 3-D in vitro metastatic landscapes

NASA Astrophysics Data System (ADS)

Liu, Liyu; Sun, Bo; Duclos, Guillaume; Kam, Yoonseok; Gatenby, Robert; Stone, Howard; Austin, Robert

2012-02-01

One well-known fact is that cancer cell genetics determines cell metastatic potentials. However, from a physics point of view, genetics as cell properties cannot directly act on metastasis. An agent is needed to unscramble the genetics first before generating dynamics for metastasis. Exactly this agent is cell behavioral phenotype, which is rarely studied due to the difficulties of real-time cell tracking in in vivo tissue. Here we have successfully constructed a micro in vitro environment with collagen based Extracellular Matrix (ECM) structures for cell 3-D metastasis. With stable nutrition (glucose) gradient inside, breast cancer cell MDA-MB-231 is able to invade inside the collagen from the nutrition poor site towards the nutrition rich site. Continuous confocal microscopy captures images of the cells every 12 hours and tracks their positions in 3-D space. The micro fluorescent beads pre-mixed inside the ECM demonstrate that invasive cells have altered the structures through mechanics. With the observation and the analysis of cell collective behaviors, we argue that game theory may exist between the pioneering cells and their followers in the metastatic cell group. The cell collaboration may explain the high efficiency of metastasis.

Safety considerations of lithium-thionyl chloride cells

NASA Astrophysics Data System (ADS)

Subbarao, Surampudi; Halpert, Gerald; Stein, Irving

1986-06-01

The use of spirally wound lithium-thionyl chloride (Li-SOCl2) cells is currently limited because of their hazardous behavior. Safety hazards have ranged from mild venting of toxic materials to violent explosions and fires. These incidents may be related to both user- and manufacturer-induced causes. Many explanations have been offered to explain the unsafe behavior of the cells under operating and abuse conditions. Explanations fall into two categories: (1) thermal mechanisms, and (2) chemical mechanisms. However, it is quite difficult to separate the two. Both may be responsible for cell venting or explosion. Some safety problems encountered with these cells also may be due to design deficiencies and ineffective quality control during cell fabrication. A well-coordinated basic and applied research program is needed to develop safe Li-SOCl2 cells. Recommendations include: (1) learnig more about Li-SOL2 cell chemistry; (2) modeling cell and battery behavior; (3) optimizing cell design for safety and performance, (4) implementing quality control procedures; and (5) educating users.

Safety considerations of lithium-thionyl chloride cells

NASA Technical Reports Server (NTRS)

Subbarao, Surampudi; Halpert, Gerald; Stein, Irving

1986-01-01

The use of spirally wound lithium-thionyl chloride (Li-SOCl2) cells is currently limited because of their hazardous behavior. Safety hazards have ranged from mild venting of toxic materials to violent explosions and fires. These incidents may be related to both user- and manufacturer-induced causes. Many explanations have been offered to explain the unsafe behavior of the cells under operating and abuse conditions. Explanations fall into two categories: (1) thermal mechanisms, and (2) chemical mechanisms. However, it is quite difficult to separate the two. Both may be responsible for cell venting or explosion. Some safety problems encountered with these cells also may be due to design deficiencies and ineffective quality control during cell fabrication. A well-coordinated basic and applied research program is needed to develop safe Li-SOCl2 cells. Recommendations include: (1) learnig more about Li-SOL2 cell chemistry; (2) modeling cell and battery behavior; (3) optimizing cell design for safety and performance, (4) implementing quality control procedures; and (5) educating users.

Luminal mitosis drives epithelial cell dispersal within the branching ureteric bud

PubMed Central

Packard, Adam; Georgas, Kylie; Michos, Odyssé; Riccio, Paul; Cebrian, Cristina; Combes, Alexander N.; Ju, Adler; Ferrer-Vaquer, Anna; Hadjantonakis, Anna-Katerina; Zong, Hui; Little, Melissa H.; Costantini, Frank

2013-01-01

Summary The ureteric bud is an epithelial tube that undergoes branching morphogenesis to form the renal collecting system. Though development of a normal kidney depends on proper ureteric bud morphogenesis, the cellular events underlying this process remain obscure. Here, we used time-lapse microscopy together with several genetic labeling methods to observe ureteric bud cell behaviors in developing mouse kidneys. We observed an unexpected cell behavior in the branching tips of the ureteric bud, which we term “mitosis-associated cell dispersal”. Pre-mitotic ureteric tip cells delaminate from the epithelium and divide within the lumen; while one daughter cell retains a basal process, allowing it to reinsert into the epithelium at the site of origin, the other daughter cell reinserts at a position one to three cell diameters away. Given the high rate of cell division in ureteric tips, this cellular behavior causes extensive epithelial cell rearrangements that may contribute to renal branching morphogenesis. PMID:24183650

Stem cell behavior on tailored porous oxide surface coatings.

PubMed

Lavenus, Sandrine; Poxson, David J; Ogievetsky, Nika; Dordick, Jonathan S; Siegel, Richard W

2015-07-01

Nanoscale surface topographies are known to have a profound influence on cell behavior, including cell guidance, migration, morphology, proliferation, and differentiation. In this study, we have observed the behavior of human mesenchymal stem cells cultured on a range of tailored porous SiO2 and TiO2 nanostructured surface coatings fabricated via glancing angle electron-beam deposition. By controlling the physical vapor deposition angle during fabrication, we could control systematically the deposited coating porosity, along with associated topographic features. Immunocytochemistry and image analysis quantitatively revealed the number of adherent cells, as well as their basic cellular morphology, on these surfaces. Signaling pathway studies showed that even with subtle changes in nanoscale surface structures, the behavior of mesenchymal stem cells was strongly influenced by the precise surface structures of these porous coatings. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evolution and morphology of microenvironment-enhanced malignancy of three-dimensional invasive solid tumors

NASA Astrophysics Data System (ADS)

Jiao, Yang; Torquato, Salvatore

2013-05-01

The emergence of invasive and metastatic behavior in malignant tumors can often lead to fatal outcomes for patients. The collective malignant tumor behavior resulting from the complex tumor-host interactions and the interactions between the tumor cells is currently poorly understood. In this paper, we employ a cellular automaton (CA) model to investigate microenvironment-enhanced malignant behaviors and morphologies of in vitro avascular invasive solid tumors in three dimensions. Our CA model incorporates a variety of microscopic-scale tumor-host interactions, including the degradation of the extracellular matrix by the malignant cells, nutrient-driven cell migration, pressure buildup due to the deformation of the microenvironment by the growing tumor, and its effect on the local tumor-host interface stability. Moreover, the effects of cell-cell adhesion on tumor growth are explicitly taken into account. Specifically, we find that while strong cell-cell adhesion can suppress the invasive behavior of the tumors growing in soft microenvironments, cancer malignancy can be significantly enhanced by harsh microenvironmental conditions, such as exposure to high pressure levels. We infer from the simulation results a qualitative phase diagram that characterizes the expected malignant behavior of invasive solid tumors in terms of two competing malignancy effects: the rigidity of the microenvironment and cell-cell adhesion. This diagram exhibits phase transitions between noninvasive and invasive behaviors. We also discuss the implications of our results for the diagnosis, prognosis, and treatment of malignant tumors.

Estimation of turgor pressure through comparison between single plant cell and pressurized shell mechanics

NASA Astrophysics Data System (ADS)

Durand-Smet, P.; Gauquelin, E.; Chastrette, N.; Boudaoud, A.; Asnacios, A.

2017-10-01

While plant growth is well known to rely on turgor pressure, it is challenging to quantify the contribution of turgor pressure to plant cell rheology. Here we used a custom-made micro-rheometer to quantify the viscoelastic behavior of isolated plant cells while varying their internal turgor pressure. To get insight into how plant cells adapt their internal pressure to the osmolarity of their medium, we compared the mechanical behavior of single plant cells to that of a simple, passive, pressurized shell: a soccer ball. While both systems exhibited the same qualitative behavior, a simple mechanical model allowed us to quantify turgor pressure regulation at the single cell scale.

The relationship between cell phone use, physical and sedentary activity, and cardiorespiratory fitness in a sample of U.S. college students

PubMed Central

2013-01-01

Background Today’s cell phones increase opportunities for activities traditionally defined as sedentary behaviors (e.g., surfing the internet, playing video games). People who participate in large amounts of sedentary behaviors, relative to those who do not, tend to be less physically active, less physically fit, and at greater risk for health problems. However, cell phone use does not have to be a sedentary behavior as these devices are portable. It can occur while standing or during mild-to-moderate intensity physical activity. Thus, the relationship between cell phone use, physical and sedentary activity, and physical fitness is unclear. The purpose of this study was to investigate these relationships among a sample of healthy college students. Methods Participants were first interviewed about their physical activity behavior and cell phone use. Then body composition was assessed and the validated self-efficacy survey for exercise behaviors completed. This was followed by a progressive exercise test on a treadmill to exhaustion. Peak oxygen consumption (VO2 peak) during exercise was used to measure cardiorespiratory fitness. Hierarchical regression was used to assess the relationship between cell phone use and cardiorespiratory fitness after controlling for sex, self-efficacy, and percent body fat. Interview data was transcribed, coded, and Chi-square analysis was used to compare the responses of low and high frequency cell phone users. Results Cell phone use was significantly (p = 0.047) and negatively (β = −0.25) related to cardio respiratory fitness independent of sex, self-efficacy, and percent fat which were also significant predictors (p < 0.05). Interview data offered several possible explanations for this relationship. First, high frequency users were more likely than low frequency users to report forgoing opportunities for physical activity in order to use their cell phones for sedentary behaviors. Second, low frequency users were more likely to report being connected to active peer groups through their cell phones and to cite this as a motivation for physical activity. Third, high levels of cell phone use indicated a broader pattern of sedentary behaviors apart from cell phone use, such as watching television. Conclusion Cell phone use, like traditional sedentary behaviors, may disrupt physical activity and reduce cardiorespiratory fitness. PMID:23800133

The relationship between cell phone use, physical and sedentary activity, and cardiorespiratory fitness in a sample of U.S. college students.

PubMed

Lepp, Andrew; Barkley, Jacob E; Sanders, Gabriel J; Rebold, Michael; Gates, Peter

2013-06-21

Today's cell phones increase opportunities for activities traditionally defined as sedentary behaviors (e.g., surfing the internet, playing video games). People who participate in large amounts of sedentary behaviors, relative to those who do not, tend to be less physically active, less physically fit, and at greater risk for health problems. However, cell phone use does not have to be a sedentary behavior as these devices are portable. It can occur while standing or during mild-to-moderate intensity physical activity. Thus, the relationship between cell phone use, physical and sedentary activity, and physical fitness is unclear. The purpose of this study was to investigate these relationships among a sample of healthy college students. Participants were first interviewed about their physical activity behavior and cell phone use. Then body composition was assessed and the validated self-efficacy survey for exercise behaviors completed. This was followed by a progressive exercise test on a treadmill to exhaustion. Peak oxygen consumption (VO2 peak) during exercise was used to measure cardiorespiratory fitness. Hierarchical regression was used to assess the relationship between cell phone use and cardiorespiratory fitness after controlling for sex, self-efficacy, and percent body fat. Interview data was transcribed, coded, and Chi-square analysis was used to compare the responses of low and high frequency cell phone users. Cell phone use was significantly (p = 0.047) and negatively (β = -0.25) related to cardio respiratory fitness independent of sex, self-efficacy, and percent fat which were also significant predictors (p < 0.05). Interview data offered several possible explanations for this relationship. First, high frequency users were more likely than low frequency users to report forgoing opportunities for physical activity in order to use their cell phones for sedentary behaviors. Second, low frequency users were more likely to report being connected to active peer groups through their cell phones and to cite this as a motivation for physical activity. Third, high levels of cell phone use indicated a broader pattern of sedentary behaviors apart from cell phone use, such as watching television. Cell phone use, like traditional sedentary behaviors, may disrupt physical activity and reduce cardiorespiratory fitness.

Measuring P-V-T Phase Behavior with a Variable Volume View Cell

ERIC Educational Resources Information Center

Hoffmann, Markus M.; Salter, Jason D.

2004-01-01

An experiment using a variable volume cell is presented where students actively control and directly observe the phase equilibrium inside the view cell. Measuring and exploring P-V-T phase behavior through dielectric constant measurements conveys the important concept that solvent behavior can be changed continuously in the sc fluid state.

Secreting and sensing the same molecule allows cells to achieve versatile social behaviors

PubMed Central

Youk, Hyun; Lim, Wendell A.

2014-01-01

Cells that secrete and sense the same signaling molecule are ubiquitous. To uncover the functional capabilities of the core ‘secrete-and-sense’ circuit motif shared by these cells, we engineered yeast to secrete and sense the mating pheromone. Perturbing each circuit element revealed parameters that control the degree to which the cell communicated with itself versus with its neighbors. This tunable interplay of self- and neighbor-communication enables cells to span a diverse repertoire of cellular behaviors. These include a cell being asocial by responding only to itself, social through quorum sensing and an isogenic population of cells splitting into social and asocial subpopulations. A mathematical model explained these behaviors. The versatility of the secrete-and-sense circuit motif may explain its recurrence across species. PMID:24503857

Interplay of differential cell mechanical properties, motility, and proliferation in emergent collective behavior of cell co-cultures

NASA Astrophysics Data System (ADS)

Sutter, Leo; Kolbman, Dan; Wu, Mingming; Ma, Minglin; Das, Moumita

The biophysics of cell co-cultures, i.e. binary systems of cell populations, is of great interest in many biological processes including formation of embryos, and tumor progression. During these processes, different types of cells with different physical properties are mixed with each other, with important consequences for cell-cell interaction, aggregation, and migration. The role of the differences in their physical properties in their collective behavior remains poorly understood. Furthermore, until recently most theoretical studies of collective cell migration have focused on two dimensional systems. Under physiological conditions, however, cells often have to navigate three dimensional and confined micro-environments. We study a confined, three-dimensional binary system of interacting, active, and deformable particles with different physical properties such as deformability, motility, adhesion, and division rates using Langevin Dynamics simulations. Our findings may provide insights into how the differences in and interplay between cell mechanical properties, division, and motility influence emergent collective behavior such as cell aggregation and segregation experimentally observed in co-cultures of breast cancer cells and healthy breast epithelial cells. This work was partially supported by a Cottrell College Science Award.

Application of First Principles Model to Spacecraft Operations

NASA Technical Reports Server (NTRS)

Timmerman, Paul; Bugga, Ratnakumar; DiStefano, Salvidor

1996-01-01

Previous models use a single phase reaction; cycled cell predicts cannot be met with a single phase; interphase conversion provides means for film aging; aging cells predictions display typical behaviors: pressure changes in NiH² cells; voltage fading upon cycling; second plateau on discharge of cycled cells; negative limited behavior for Ni-Cds.

A Micromechanics Finite Element Model for Studying the Mechanical Behavior of Spray-On Foam Insulation (SOFI)

NASA Technical Reports Server (NTRS)

Ghosn, Louis J.; Sullivan, Roy M.; Lerch, Bradley A.

2006-01-01

A micromechanics model has been constructed to study the mechanical behavior of spray-on foam insulation (SOFI) for the external tank. The model was constructed using finite elements representing the fundamental repeating unit of the SOFI microstructure. The details of the micromechanics model were based on cell observations and measured average cell dimensions discerned from photomicrographs. The unit cell model is an elongated Kelvin model (fourteen-sided polyhedron with 8 hexagonal and six quadrilateral faces), which will pack to a 100% density. The cell faces and cell edges are modeled using three-dimensional 20-node brick elements. Only one-eighth of the cell is modeled due to symmetry. By exercising the model and correlating the results with the macro-mechanical foam behavior obtained through material characterization testing, the intrinsic stiffness and Poisson s Ratio of the polymeric cell walls and edges are determined as a function of temperature. The model is then exercised to study the unique and complex temperature-dependent mechanical behavior as well as the fracture initiation and propagation at the microscopic unit cell level.

Multiscale Modeling of Cell Interaction in Angiogenesis: From the Micro- to Macro-scale

NASA Astrophysics Data System (ADS)

Pillay, Samara; Maini, Philip; Byrne, Helen

Solid tumors require a supply of nutrients to grow in size. To this end, tumors induce the growth of new blood vessels from existing vasculature through the process of angiogenesis. In this work, we use a discrete agent-based approach to model the behavior of individual endothelial cells during angiogenesis. We incorporate crowding effects through volume exclusion, motility of cells through biased random walks, and include birth and death processes. We use the transition probabilities associated with the discrete models to determine collective cell behavior, in terms of partial differential equations, using a Markov chain and master equation framework. We find that the cell-level dynamics gives rise to a migrating cell front in the form of a traveling wave on the macro-scale. The behavior of this front depends on the cell interactions that are included and the extent to which volume exclusion is taken into account in the discrete micro-scale model. We also find that well-established continuum models of angiogenesis cannot distinguish between certain types of cell behavior on the micro-scale. This may impact drug development strategies based on these models.

Correlations between the Dielectric Properties and Exterior Morphology of Cells Revealed by Dielectrophoretic Field-Flow Fractionation

PubMed Central

Gascoyne, Peter R. C.; Shim, Sangjo; Noshari, Jamileh; Becker, Frederick F.; Stemke-Hale, Katherine

2013-01-01

Although dielectrophoresis (DEP) has great potential for addressing clinical cell isolation problems based on cell dielectric differences, a biological basis for predicting the DEP behavior of cells has been lacking. Here, the dielectric properties of the NCI-60 panel of tumor cell types have been measured by dielectrophoretic (DEP) field-flow fractionation, correlated with the exterior morphologies of the cells during growth, and compared with the dielectric and morphological characteristics of the subpopulations of peripheral blood. In agreement with earlier findings, cell total capacitance varied with both cell size and plasma membrane folding and the dielectric properties of the NCI-60 cell types in suspension reflected the plasma membrane area and volume of the cells at their growth sites. Therefore, the behavior of cells in DEP-based manipulations is largely determined by their exterior morphological characteristics prior to release into suspension. As a consequence, DEP is able to discriminate between cells of similar size having different morphological origins, offering a significant advantage over size-based filtering for isolating circulating tumor cells, for example. The findings provide a framework for anticipating cell dielectric behavior on the basis of structure-function relationships and suggest that DEP should be widely applicable as a surface marker-independent method for sorting cells. PMID:23172680

Mechanical behavior in living cells consistent with the tensegrity model

NASA Technical Reports Server (NTRS)

Wang, N.; Naruse, K.; Stamenovic, D.; Fredberg, J. J.; Mijailovich, S. M.; Tolic-Norrelykke, I. M.; Polte, T.; Mannix, R.; Ingber, D. E.

2001-01-01

Alternative models of cell mechanics depict the living cell as a simple mechanical continuum, porous filament gel, tensed cortical membrane, or tensegrity network that maintains a stabilizing prestress through incorporation of discrete structural elements that bear compression. Real-time microscopic analysis of cells containing GFP-labeled microtubules and associated mitochondria revealed that living cells behave like discrete structures composed of an interconnected network of actin microfilaments and microtubules when mechanical stresses are applied to cell surface integrin receptors. Quantitation of cell tractional forces and cellular prestress by using traction force microscopy confirmed that microtubules bear compression and are responsible for a significant portion of the cytoskeletal prestress that determines cell shape stability under conditions in which myosin light chain phosphorylation and intracellular calcium remained unchanged. Quantitative measurements of both static and dynamic mechanical behaviors in cells also were consistent with specific a priori predictions of the tensegrity model. These findings suggest that tensegrity represents a unified model of cell mechanics that may help to explain how mechanical behaviors emerge through collective interactions among different cytoskeletal filaments and extracellular adhesions in living cells.

Role of Proteome Physical Chemistry in Cell Behavior.

PubMed

Ghosh, Kingshuk; de Graff, Adam M R; Sawle, Lucas; Dill, Ken A

2016-09-15

We review how major cell behaviors, such as bacterial growth laws, are derived from the physical chemistry of the cell's proteins. On one hand, cell actions depend on the individual biological functionalities of their many genes and proteins. On the other hand, the common physics among proteins can be as important as the unique biology that distinguishes them. For example, bacterial growth rates depend strongly on temperature. This dependence can be explained by the folding stabilities across a cell's proteome. Such modeling explains how thermophilic and mesophilic organisms differ, and how oxidative damage of highly charged proteins can lead to unfolding and aggregation in aging cells. Cells have characteristic time scales. For example, E. coli can duplicate as fast as 2-3 times per hour. These time scales can be explained by protein dynamics (the rates of synthesis and degradation, folding, and diffusional transport). It rationalizes how bacterial growth is slowed down by added salt. In the same way that the behaviors of inanimate materials can be expressed in terms of the statistical distributions of atoms and molecules, some cell behaviors can be expressed in terms of distributions of protein properties, giving insights into the microscopic basis of growth laws in simple cells.

Tuning cell adhesion on polymeric and nanocomposite surfaces: Role of topography versus superhydrophobicity.

PubMed

Zangi, Sepideh; Hejazi, Iman; Seyfi, Javad; Hejazi, Ehsan; Khonakdar, Hossein Ali; Davachi, Seyed Mohammad

2016-06-01

Development of surface modification procedures which allow tuning the cell adhesion on the surface of biomaterials and devices is of great importance. In this study, the effects of different topographies and wettabilities on cell adhesion behavior of polymeric surfaces are investigated. To this end, an improved phase separation method was proposed to impart various wettabilities (hydrophobic and superhydrophobic) on polypropylene surfaces. Surface morphologies and compositions were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cell culture was conducted to evaluate the adhesion of 4T1 mouse mammary tumor cells. It was found that processing conditions such as drying temperature is highly influential in cell adhesion behavior due to the formation of an utterly different surface topography. It was concluded that surface topography plays a more significant role in cell adhesion behavior rather than superhydrophobicity since the nano-scale topography highly inhibited the cell adhesion as compared to the micro-scale topography. Such cell repellent behavior could be very useful in many biomedical devices such as those in drug delivery and blood contacting applications as well as biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of temperature on the aging behavior of 18650-type lithium ion cells: A comprehensive approach combining electrochemical characterization and post-mortem analysis

NASA Astrophysics Data System (ADS)

Friesen, Alex; Mönnighoff, Xaver; Börner, Markus; Haetge, Jan; Schappacher, Falko M.; Winter, Martin

2017-02-01

The understanding of the aging behavior of lithium ion batteries in automotive and energy storage applications is essential for the acceptance of the technology. Therefore, aging experiments were conducted on commercial 18650-type state-of-the-art cells to determine the influence of the temperature during electrochemical cycling on the aging behavior of the different cell components. The cells, based on Li(Ni0.5Co0.2Mn0.3)O2 (NCM532)/graphite, were aged at 20 °C and 45 °C to different states of health. The electrochemical performance of the investigated cells shows remarkable differences depending on the cycling temperature. At contrast to the expected behavior, the cells cycled at 45 °C show a better electrochemical performance over lifetime than the cells cycled at 20 °C. Comprehensive post-mortem analyses revealed the main aging mechanisms, showing a complex interaction between electrodes and electrolyte. The main aging mechanisms of the cells cycled at 45 °C differ strongly at contrast to cells cycled at 20 °C. A strong correlation between the formed SEI, the electrolyte composition and the electrochemical performance over lifetime was observed.

Subcellular and supracellular mechanical stress prescribes cytoskeleton behavior in Arabidopsis cotyledon pavement cells

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

Sampathkumar, Arun; Krupinski, Pawel; Wightman, Raymond

Although it is a central question in biology, how cell shape controls intracellular dynamics largely remains an open question. Here, we show that the shape of Arabidopsis pavement cells creates a stress pattern that controls microtubule orientation, which then guides cell wall reinforcement. Live-imaging, combined with modeling of cell mechanics, shows that microtubules align along the maximal tensile stress direction within the cells, and atomic force microscopy demonstrates that this leads to reinforcement of the cell wall parallel to the microtubules. This feedback loop is regulated: cell-shape derived stresses could be overridden by imposed tissue level stresses, showing how competitionmore » between subcellular and supracellular cues control microtubule behavior. Furthermore, at the microtubule level, we identified an amplification mechanism in which mechanical stress promotes the microtubule response to stress by increasing severing activity. These multiscale feedbacks likely contribute to the robustness of microtubule behavior in plant epidermis.« less

Subcellular and supracellular mechanical stress prescribes cytoskeleton behavior in Arabidopsis cotyledon pavement cells

DOE PAGES

Sampathkumar, Arun; Krupinski, Pawel; Wightman, Raymond; ...

2014-04-16

Although it is a central question in biology, how cell shape controls intracellular dynamics largely remains an open question. Here, we show that the shape of Arabidopsis pavement cells creates a stress pattern that controls microtubule orientation, which then guides cell wall reinforcement. Live-imaging, combined with modeling of cell mechanics, shows that microtubules align along the maximal tensile stress direction within the cells, and atomic force microscopy demonstrates that this leads to reinforcement of the cell wall parallel to the microtubules. This feedback loop is regulated: cell-shape derived stresses could be overridden by imposed tissue level stresses, showing how competitionmore » between subcellular and supracellular cues control microtubule behavior. Furthermore, at the microtubule level, we identified an amplification mechanism in which mechanical stress promotes the microtubule response to stress by increasing severing activity. These multiscale feedbacks likely contribute to the robustness of microtubule behavior in plant epidermis.« less

Pineal Photoreceptor Cells Are Required for Maintaining the Circadian Rhythms of Behavioral Visual Sensitivity in Zebrafish

PubMed Central

Li, Xinle; Montgomery, Jake; Cheng, Wesley; Noh, Jung Hyun; Hyde, David R.; Li, Lei

2012-01-01

In non-mammalian vertebrates, the pineal gland functions as the central pacemaker that regulates the circadian rhythms of animal behavior and physiology. We generated a transgenic zebrafish line [Tg(Gnat2:gal4-VP16/UAS:nfsB-mCherry)] in which the E. coli nitroreductase is expressed in pineal photoreceptor cells. In developing embryos and young adults, the transgene is expressed in both retinal and pineal photoreceptor cells. During aging, the expression of the transgene in retinal photoreceptor cells gradually diminishes. By 8 months of age, the Gnat2 promoter-driven nitroreductase is no longer expressed in retinal photoreceptor cells, but its expression in pineal photoreceptor cells persists. This provides a tool for selective ablation of pineal photoreceptor cells, i.e., by treatments with metronidazole. In the absence of pineal photoreceptor cells, the behavioral visual sensitivity of the fish remains unchanged; however, the circadian rhythms of rod and cone sensitivity are diminished. Brief light exposures restore the circadian rhythms of behavioral visual sensitivity. Together, the data suggest that retinal photoreceptor cells respond to environmental cues and are capable of entraining the circadian rhythms of visual sensitivity; however, they are insufficient for maintaining the rhythms. Cellular signals from the pineal photoreceptor cells may be required for maintaining the circadian rhythms of visual sensitivity. PMID:22815753

Utilization of a photoactivatable antigen system to examine B-cell probing termination and the B-cell receptor sorting mechanisms during B-cell activation

PubMed Central

Wang, Jing; Tang, Shan; Wan, Zhengpeng; Gao, Yiren; Cao, Yiyun; Yi, Junyang; Si, Yanyan; Zhang, Haowen; Liu, Lei; Liu, Wanli

2016-01-01

Antigen binding to the B-cell receptor (BCR) induces several responses, resulting in B-cell activation, proliferation, and differentiation. However, it has been difficult to study these responses due to their dynamic, fast, and transient nature. Here, we attempted to solve this problem by developing a controllable trigger point for BCR and antigen recognition through the construction of a photoactivatable antigen, caged 4-hydroxy-3-nitrophenyl acetyl (caged-NP). This photoactivatable antigen system in combination with live cell and single molecule imaging techniques enabled us to illuminate the previously unidentified B-cell probing termination behaviors and the precise BCR sorting mechanisms during B-cell activation. B cells in contact with caged-NP exhibited probing behaviors as defined by the unceasing extension of membrane pseudopods in random directions. Further analyses showed that such probing behaviors are cell intrinsic with strict dependence on F-actin remodeling but not on tonic BCR signaling. B-cell probing behaviors were terminated within 4 s after photoactivation, suggesting that this response was sensitive and specific to BCR engagement. The termination of B-cell probing was concomitant with the accumulation response of the BCRs into the BCR microclusters. We also determined the Brownian diffusion coefficient of BCRs from the same B cells before and after BCR engagement. The analysis of temporally segregated single molecule images of both BCR and major histocompatibility complex class I (MHC-I) demonstrated that antigen binding induced trapping of BCRs into the BCR microclusters is a fundamental mechanism for B cells to acquire antigens. PMID:26764382

Revelation of Different Nanoparticle-Uptake Behavior in Two Standard Cell Lines NIH/3T3 and A549 by Flow Cytometry and Time-Lapse Imaging

PubMed Central

Jochums, André; Friehs, Elsa; Sambale, Franziska; Lavrentieva, Antonina; Bahnemann, Detlef; Scheper, Thomas

2017-01-01

The uptake of nanomaterials into different cell types is a central pharmacological issue for the determination of nanotoxicity as well as for the development of drug delivery strategies. Most responses of the cells depend on their intracellular interactions with nanoparticles (NPs). Uptake behavior can be precisely investigated in vitro, with sensitive high throughput methods such as flow cytometry. In this study, we investigated two different standard cell lines, human lung carcinoma (A549) and mouse fibroblast (NIH/3T3) cells, regarding their uptake behavior of titanium dioxide NPs. Cells were incubated with different concentrations of TiO2 NPs and samples were taken at certain time points to compare the uptake kinetics of both cell lines. Samples were analyzed with the help of flow cytometry by studying changes in the side and forward scattering signal. To additionally enable a detection via fluorescence, NPs were labeled with the fluorescent dye fluorescein isothiocyanate (FITC) and propidium iodide (PI). We found that NIH/3T3 cells take up the studied NPs more efficiently than A549 cells. These findings were supported by time-lapse microscopic imaging of the cells incubated with TiO2 NPs. Our results confirm that the uptake behavior of individual cell types has to be considered before interpreting any results of nanomaterial studies. PMID:29051447

Fabrication of a multi-layer three-dimensional scaffold with controlled porous micro-architecture for application in small intestine tissue engineering.

PubMed

Knight, Toyin; Basu, Joydeep; Rivera, Elias A; Spencer, Thomas; Jain, Deepak; Payne, Richard

2013-01-01

Various methods can be employed to fabricate scaffolds with characteristics that promote cell-to-material interaction. This report examines the use of a novel technique combining compression molding with particulate leaching to create a unique multi-layered scaffold with differential porosities and pore sizes that provides a high level of control to influence cell behavior. These cell behavioral responses were primarily characterized by bridging and penetration of two cell types (epithelial and smooth muscle cells) on the scaffold in vitro. Larger pore sizes corresponded to an increase in pore penetration, and a decrease in pore bridging. In addition, smaller cells (epithelial) penetrated further into the scaffold than larger cells (smooth muscle cells). In vivo evaluation of a multi-layered scaffold was well tolerated for 75 d in a rodent model. This data shows the ability of the components of multi-layered scaffolds to influence cell behavior, and demonstrates the potential for these scaffolds to promote desired tissue outcomes in vivo.

Planar Cell Polarity Pathway – Coordinating morphogenetic cell behaviors with embryonic polarity

PubMed Central

Gray, Ryan S.; Roszko, Isabelle; Solnica-Krezel, Lilianna

2011-01-01

Planar cell polarization entails establishment of cellular asymmetries within the tissue plane. An evolutionarily conserved Planar Cell Polarity (PCP) signaling system employs intra- and intercellular feedback interactions between its core components, including Frizzled, Van Gogh, Flamingo, Prickle and Dishevelled, to establish their characteristic asymmetric intracellular distributions and coordinate planar polarity of cell populations. By translating global patterning information into asymmetries of cell membranes and intracellular organelles, PCP signaling coordinates morphogenetic behaviors of individual cells and cell populations with the embryonic polarity. In vertebrates, by polarizing cilia in the node/Kupffer’s vesicle, PCP signaling links the anteroposterior to left-right embryonic polarity. PMID:21763613

The cell monolayer trajectory from the system state point of view.

PubMed

Stys, Dalibor; Vanek, Jan; Nahlik, Tomas; Urban, Jan; Cisar, Petr

2011-10-01

Time-lapse microscopic movies are being increasingly utilized for understanding the derivation of cell states and predicting cell future. Often, fluorescence and other types of labeling are not available or desirable, and cell state-definitions based on observable structures must be used. We present the methodology for cell behavior recognition and prediction based on the short term cell recurrent behavior analysis. This approach has theoretical justification in non-linear dynamics theory. The methodology is based on the general stochastic systems theory which allows us to define the cell states, trajectory and the system itself. We introduce the usage of a novel image content descriptor based on information contribution (gain) by each image point for the cell state characterization as the first step. The linkage between the method and the general system theory is presented as a general frame for cell behavior interpretation. We also discuss extended cell description, system theory and methodology for future development. This methodology may be used for many practical purposes, ranging from advanced, medically relevant, precise cell culture diagnostics to very utilitarian cell recognition in a noisy or uneven image background. In addition, the results are theoretically justified.

Distracted driving behaviors of adults while children are in the car.

PubMed

Roney, Linda; Violano, Pina; Klaus, Greg; Lofthouse, Rebecca; Dziura, James

2013-10-01

Cell phone use while driving is common and can result in driver distraction. However, data on the frequency of this behavior with other occupants in the vehicle are lacking. This study investigates whether adult drivers engage in cell phone use with passengers in the car and determines whether the frequency of these behaviors was modified if the passenger was a child. Subjects (N = 539) who have driven children during the previous 30 days were recruited to complete a survey regarding their cell phone usage while driving. The inclusion criteria of participants were as follows: 18 years or older with a valid driver's license, owns/uses a cell phone, drives with children, and reads English. Results were reported on a 4-point Likert scale (always, often, rarely, and never). Eighty percent of respondents reported cell phone use in some way while driving with children. As compared with similar behaviors when driving alone or with adult passengers, the odds of reporting "always" compared with "often, rarely, or never" of holding a cell phone in hand was 0.66 when driving with children. No significant differences were noted for the following variables: use of a blue tooth device or use of a cell phone to speak or text when parked. Cell phone use while driving is common. Distracted driving behaviors, although less frequent, persist when children are passengers in the vehicle. Further research into the effect of cell phone-related distracted driving behaviors of adults with child passengers is needed to address this public health concern.

Controlling micro- and nano-environment of tumor and stem cells for novel research and therapy of brain cancer

NASA Astrophysics Data System (ADS)

Smith, Christopher Lloyd

The use of modern technologies in cancer research has engendered a great deal of excitement. Many of these advanced approaches involve in-depth mathematical analyses of the inner working of cells, via genomic and proteomic analyses. However these techniques may not be ideal for the study of complex cell phenotypes and behaviors. This dissertation explores cancer and potential therapies through phenotypic analysis of cell behaviors, an alternative approach. We employ this experimental framework to study brain cancer (glioma), a particularly formidable example of this diverse ailment. Through the application of micro- and nanotechnology, we carefully control the surrounding environments of cells to understand their responses to various cues and to manipulate their behaviors. Subsequently we obtain clinically relevant information that allows better understanding of glioma, and enhancement of potential therapies. We first aim to address brain tumor dispersal, through analysis of cell migration. Utilizing nanometer-scale topographic models of the extracellular matrix, we study the migratory response of glioma cells to various stimuli in vitro. Second, we implement knowledge gained from these investigations to define characteristics of tumor progression in patients, and to develop treatments inhibiting cell migration. Next we use microfluidic and nanotopographic models to study the behaviors of stem cells in vitro. Here we attempt to improve their abilities to deliver therapeutic proteins to cancer, an innovative treatment approach. We analyze the multi-step process by which adipose-derived stem cells naturally home to tumor sites, and identify numerous environmental perturbations to enhance this behavior. Finally, we attempt to demonstrate that these cell culture-based manipulations can enhance the localization of adipose stem cells to glioma in vivo using animal models. Throughout this work we utilize environmental cues to analyze and induce particular behaviors in cells. We further demonstrate that this general technique can be used to determine clinically relevant tumor characteristics, to identify potential drug targets, and to enhance potential therapies. Therefore this thesis illuminates a novel framework for experimentation into cancer, and specifically advances two treatment approaches. We anticipate that the methodologies described in this study will prove useful to various branches of medicine and biological research.

A novel honeycomb cell assay kit designed for evaluating horizontal cell migration in response to functionalized self-assembling peptide hydrogels

NASA Astrophysics Data System (ADS)

Guan, Fengyi; Lu, Jiaju; Wang, Xiumei

2017-03-01

A clear understanding on cell migration behaviors contributes to designing novel biomaterials in tissue engineering and elucidating related tissue regeneration processes. Many traditional evaluation methods on cell migration including scratch assay and transwell migration assay possess all kinds of limitations. In this study, a novel honeycomb cell assay kit was designed and made of photosensitive resin by 3D printing. This kit has seven hexagonal culture chambers so that it can evaluate the horizontal cell migration behavior in response to six surrounding environments simultaneously, eliminating the effect of gravity on cells. Here this cell assay kit was successfully applied to evaluate endothelial cell migration cultured on self-assembling peptide (SAP) RADA (AcN-RADARADARADARADA-CONH2) nanofiber hydrogel toward different functionalized SAP hydrogels. Our results indicated that the functionalized RADA hydrogels with different concentration of bioactive motifs of KLT or PRG could induce cell migration in a dose-dependent manner. The total number and migration distance of endothelial cells on functionalized SAP hydrogels significantly increased with increasing concentration of bioactive motif PRG or KLT. Therefore, the honeycomb cell assay kit provides a simple, efficient and convenient tool to investigate cell migration behavior in response to multi-environments simultaneously.

An Observation-Driven Agent-Based Modeling and Analysis Framework for C. elegans Embryogenesis.

PubMed

Wang, Zi; Ramsey, Benjamin J; Wang, Dali; Wong, Kwai; Li, Husheng; Wang, Eric; Bao, Zhirong

2016-01-01

With cutting-edge live microscopy and image analysis, biologists can now systematically track individual cells in complex tissues and quantify cellular behavior over extended time windows. Computational approaches that utilize the systematic and quantitative data are needed to understand how cells interact in vivo to give rise to the different cell types and 3D morphology of tissues. An agent-based, minimum descriptive modeling and analysis framework is presented in this paper to study C. elegans embryogenesis. The framework is designed to incorporate the large amounts of experimental observations on cellular behavior and reserve data structures/interfaces that allow regulatory mechanisms to be added as more insights are gained. Observed cellular behaviors are organized into lineage identity, timing and direction of cell division, and path of cell movement. The framework also includes global parameters such as the eggshell and a clock. Division and movement behaviors are driven by statistical models of the observations. Data structures/interfaces are reserved for gene list, cell-cell interaction, cell fate and landscape, and other global parameters until the descriptive model is replaced by a regulatory mechanism. This approach provides a framework to handle the ongoing experiments of single-cell analysis of complex tissues where mechanistic insights lag data collection and need to be validated on complex observations.

Nanoscale TiO2 nanotubes govern the biological behavior of human glioma and osteosarcoma cells

PubMed Central

Tian, Ang; Qin, Xiaofei; Wu, Anhua; Zhang, Hangzhou; Xu, Quan; Xing, Deguang; Yang, He; Qiu, Bo; Xue, Xiangxin; Zhang, Dongyong; Dong, Chenbo

2015-01-01

Cells respond to their surroundings through an interactive adhesion process that has direct effects on cell proliferation and migration. This research was designed to investigate the effects of TiO2 nanotubes with different topographies and structures on the biological behavior of cultured cells. The results demonstrated that the nanotube diameter, rather than the crystalline structure of the coatings, was a major factor for the biological behavior of the cultured cells. The optimal diameter of the nanotubes was 20 nm for cell adhesion, migration, and proliferation in both glioma and osteosarcoma cells. The expression levels of vitronectin and phosphor-focal adhesion kinase were affected by the nanotube diameter; therefore, it is proposed that the responses of vitronectin and phosphor-focal adhesion kinase to the nanotube could modulate cell fate. In addition, the geometry and size of the nanotube coating could regulate the degree of expression of acetylated α-tubulin, thus indirectly modulating cell migration behavior. Moreover, the expression levels of apoptosis-associated proteins were influenced by the topography. In conclusion, a nanotube diameter of 20 nm was the critical threshold that upregulated the expression level of Bcl-2 and obviously decreased the expression levels of Bax and caspase-3. This information will be useful for future biomedical and clinical applications. PMID:25848261

Active elastic dimers: cells moving on rigid tracks.

PubMed

Lopez, J H; Das, Moumita; Schwarz, J M

2014-09-01

Experiments suggest that the migration of some cells in the three-dimensional extracellular matrix bears strong resemblance to one-dimensional cell migration. Motivated by this observation, we construct and study a minimal one-dimensional model cell made of two beads and an active spring moving along a rigid track. The active spring models the stress fibers with their myosin-driven contractility and α-actinin-driven extendability, while the friction coefficients of the two beads describe the catch and slip-bond behaviors of the integrins in focal adhesions. In the absence of active noise, net motion arises from an interplay between active contractility (and passive extendability) of the stress fibers and an asymmetry between the front and back of the cell due to catch-bond behavior of integrins at the front of the cell and slip-bond behavior of integrins at the back. We obtain reasonable cell speeds with independently estimated parameters. We also study the effects of hysteresis in the active spring, due to catch-bond behavior and the dynamics of cross linking, and the addition of active noise on the motion of the cell. Our model highlights the role of α-actinin in three-dimensional cell motility and does not require Arp2/3 actin filament nucleation for net motion.

A comparison study on the behavior of human endometrial stem cell-derived osteoblast cells on PLGA/HA nanocomposite scaffolds fabricated by electrospinning and freeze-drying methods.

PubMed

Namini, Mojdeh Salehi; Bayat, Neda; Tajerian, Roxana; Ebrahimi-Barough, Somayeh; Azami, Mahmoud; Irani, Shiva; Jangjoo, Saranaz; Shirian, Sadegh; Ai, Jafar

2018-03-27

An engineered tissue structure is an artificial scaffold combined with cells and signaling factors. Among various polymers, the polylactide-co-glycolide/hydroxyapatite (PLGA/HA) has attracted much attention due to their optimal properties. The aim of this study was to study the behavior of human endometrial stem cell (hEnSC)-derived osteoblast cells cultured on PLGA/HA nanocomposite scaffolds. hEnSCs were isolated and exposed to osteogenic media for 21 days. Differentiated cells were cultured on PLGA/HA synthetic scaffolds. The PLGA/HA-based nanocomposite scaffolds were fabricated using either electrospinning or freeze-drying methods. Behavior of the cells was evaluated a week after seeding hEnSC-derived osteoblast-like cells on these scaffolds. Osteogenesis was investigated in terms of alkaline phosphatase activity, gene expression, immunocytochemistry (ICC), proliferation, and scanning electron microscopy (SEM). Moreover, scaffold properties, such as pore size and morphology of the cells, onto the scaffolds were evaluated using SEM. Furthermore, biocompatibility of these scaffolds was confirmed by 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The matrix mineralization was proved by alizarin red staining, and the osteogenic media-treated cultures positively expressed osteocalcin and osteopontin markers. Moreover, qRT-PCR results confirmed the positive gene expression of osteopontin and osteonectin in the differentiated osteoblast-like cells. The results of behavior assessment of the cultured cells on electrospinning and freeze-dried scaffolds showed that the behavior of the cultured cells on the freeze-dried PLGA/HA scaffolds was significantly better than the electrospinning PLGA/HA scaffolds. It has been shown that the freeze-dried PLGA/HA nanocomposite scaffolds can appropriately support the attachment and proliferation of the differentiated osteoblast cells and are a suitable candidate for bone tissue engineering.

Cellular behavior controlled by bio-inspired and geometry-tunable nanohairs.

PubMed

Heo, Chaejeong; Jeong, Chanho; Im, Hyeon Seong; Kim, Jong Uk; Woo, Juhyun; Lee, Ji Yeon; Park, Byeonghak; Suh, Minah; Kim, Tae-Il

2017-11-23

A cicada wing has a biocidal feature of rupturing the membrane of cells, while the cactus spine can transmit a water drop to the stem of the plant. Both of these properties have evolved from their respective unique structures. Here, we endeavor to develop geometry-controllable nanohairs that mimic the cicada's wing-like vertical hairs and the cactus spine-like stooped hairs, and to quantitatively characterize the cell migration behavior of the hairy structures. It was found that the neuroblastoma cells are highly sensitive to the variation of surfaces: flat, vertical, and stooped nanohairs (100 nm diameter and 900 nm height). The cells on the vertical hairs showed significantly decreased proliferation. It was found that the behavior of cells cultured on stooped nanohairs is strongly influenced by the direction of the stooped pattern of hairs when we quantitatively measured the migration of cells on flat, vertical, and stooped structures. However, the cells on the flat structures showed random movement and the cells on the vertical nanohairs restricted the nanohair movement. Cells on the stooped structure showed higher forward migration preference compared to that of the other structures. Furthermore, we found that these cellular behaviors on the different patterns of nanohairs were affected by intracellular actin flament change. Consistent with these results, the vertical and stooped structures can facilitate the control of cell viability and guide directional migration for biomedical applications such as organogenesis.

Cell and defect behavior in lithium-counterdoped solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Mehta, S.; Swartz, C. K.

1984-01-01

Some n(+)/p cells in which lithium is introduced as a counterdopant, by ion-implantation, into the cell's boron-doped p-region were studied. To determine if the cells radiation resistance could be significantly improved by lithium counterdoping. Defect behavior was related to cell performance using deep level transient spectroscopy. Results indicate a significantly increased radiation resistance for the lithium counterdoped cells when compared to the boron doped 1 ohm-cm control cell. The increased radiation resistance of the lithium counterdoped cells is due to the complexing of lithium with divacancies and boron. It is speculated that complexing with oxygen and single vacancies also contributes to the increased radiation resistance. Counterdoping silicon with lithium results in a different set of defects.

Radiation damage and defect behavior in ion-implanted, lithium counterdoped silicon solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Mehta, S.; Swartz, C. K.

1984-01-01

Boron doped silicon n+p solar cells were counterdoped with lithium by ion implantation and the resuitant n+p cells irradiated by 1 MeV electrons. The function of fluence and a Deep Level Transient Spectroscopy (DLTS) was studied to correlate defect behavior with cell performance. It was found that the lithium counterdoped cells exhibited significantly increased radiation resistance when compared to boron doped control cells. It is concluded that the annealing behavior is controlled by dissociation and recombination of defects. The DLTS studies show that counterdoping with lithium eliminates at least three deep level defects and results in three new defects. It is speculated that the increased radiation resistance of the counterdoped cells is due primarily to the interaction of lithium with oxygen, single vacanies and divacancies and that the lithium-oxygen interaction is the most effective in contributing to the increased radiation resistance.

Radiation damage and defect behavior in ion-implanted, lithium counterdoped silicon solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Mehta, S.; Swartz, C. K.

1984-01-01

Boron doped silicon n+p solar cells were counterdoped with lithium by ion implanation and the resultant n+p cells irradiated by 1 MeV electrons. The function of fluence and a Deep Level Transient Spectroscopy (DLTS) was studied to correlate defect behavior with cell performance. It was found that the lithium counterdoped cells exhibited significantly increased radiation resistance when compared to boron doped control cells. It is concluded that the annealing behavior is controlled by dissociation and recombination of defects. The DLTS studies show that counterdoping with lithium eliminates at least three deep level defects and results in three new defects. It is speculated that the increased radiation resistance of the counterdoped cells is due primarily to the interaction of lithium with oxygen, single vacancies and divacancies and that the lithium-oxygen interaction is the most effective in contributing to the increased radiation resistance.

Electrokinesis is a microbial behavior that requires extracellular electron transport

PubMed Central

Harris, H. W.; El-Naggar, M. Y.; Bretschger, O.; Ward, M. J.; Romine, M. F.; Obraztsova, A. Y.; Nealson, K. H.

2009-01-01

We report a previously undescribed bacterial behavior termed electrokinesis. This behavior was initially observed as a dramatic increase in cell swimming speed during reduction of solid MnO2 particles by the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1. The same behavioral response was observed when cells were exposed to small positive applied potentials at the working electrode of a microelectrochemical cell and could be tuned by adjusting the potential on the working electrode. Electrokinesis was found to be different from both chemotaxis and galvanotaxis but was absent in mutants defective in electron transport to solid metal oxides. Using in situ video microscopy and cell tracking algorithms, we have quantified the response for different strains of Shewanella and shown that the response correlates with current-generating capacity in microbial fuel cells. The electrokinetic response was only exhibited by a subpopulation of cells closest to the MnO2 particles or electrodes. In contrast, the addition of 1 mM 9,10-anthraquinone-2,6-disulfonic acid, a soluble electron shuttle, led to increases in motility in the entire population. Electrokinesis is defined as a behavioral response that requires functional extracellular electron transport and that is observed as an increase in cell swimming speeds and lengthened paths of motion that occur in the proximity of a redox active mineral surface or the working electrode of an electrochemical cell. PMID:20018675

Patient-specific modeling and analysis of dynamic behavior of individual sickle red blood cells under hypoxic conditions

NASA Astrophysics Data System (ADS)

Li, Xuejin; Du, E.; Li, Zhen; Tang, Yu-Hang; Lu, Lu; Dao, Ming; Karniadakis, George

2015-11-01

Sickle cell anemia is an inherited blood disorder exhibiting heterogeneous morphology and abnormal dynamics under hypoxic conditions. We developed a time-dependent cell model that is able to simulate the dynamic processes of repeated sickling and unsickling of red blood cells (RBCs) under physiological conditions. By using the kinetic cell model with parameters derived from patient-specific data, we present a mesoscopic computational study of the dynamic behavior of individual sickle RBCs flowing in a microfluidic channel with multiple microgates. We investigate how individual sickle RBCs behave differently from healthy ones in channel flow, and analyze the alteration of cellular behavior and response to single-cell capillary obstruction induced by cell rheologic rigidification and morphological change due to cell sickling under hypoxic conditions. We also simulate the flow dynamics of sickle RBCs treated with hydroxyurea (HU) and quantify the relative enhancement of hemodynamic performance of HU. This work was supported by the National Institutes of Health (NIH) Grant U01HL114476.

Subcellular and supracellular mechanical stress prescribes cytoskeleton behavior in Arabidopsis cotyledon pavement cells

PubMed Central

Sampathkumar, Arun; Krupinski, Pawel; Wightman, Raymond; Milani, Pascale; Berquand, Alexandre; Boudaoud, Arezki; Hamant, Olivier; Jönsson, Henrik; Meyerowitz, Elliot M

2014-01-01

Although it is a central question in biology, how cell shape controls intracellular dynamics largely remains an open question. Here, we show that the shape of Arabidopsis pavement cells creates a stress pattern that controls microtubule orientation, which then guides cell wall reinforcement. Live-imaging, combined with modeling of cell mechanics, shows that microtubules align along the maximal tensile stress direction within the cells, and atomic force microscopy demonstrates that this leads to reinforcement of the cell wall parallel to the microtubules. This feedback loop is regulated: cell-shape derived stresses could be overridden by imposed tissue level stresses, showing how competition between subcellular and supracellular cues control microtubule behavior. Furthermore, at the microtubule level, we identified an amplification mechanism in which mechanical stress promotes the microtubule response to stress by increasing severing activity. These multiscale feedbacks likely contribute to the robustness of microtubule behavior in plant epidermis. DOI: http://dx.doi.org/10.7554/eLife.01967.001 PMID:24740969

Metabolic Adaptations of Azospirillum brasilense to Oxygen Stress by Cell-to-Cell Clumping and Flocculation

PubMed Central

Bible, Amber N.; Khalsa-Moyers, Gurusahai K.; Mukherjee, Tanmoy; Green, Calvin S.; Mishra, Priyanka; Purcell, Alicia; Aksenova, Anastasia; Hurst, Gregory B.

2015-01-01

The ability of bacteria to monitor their metabolism and adjust their behavior accordingly is critical to maintain competitiveness in the environment. The motile microaerophilic bacterium Azospirillum brasilense navigates oxygen gradients by aerotaxis in order to locate low oxygen concentrations that can support metabolism. When cells are exposed to elevated levels of oxygen in their surroundings, motile A. brasilense cells implement an alternative response to aerotaxis and form transient clumps by cell-to-cell interactions. Clumping was suggested to represent a behavior protecting motile cells from transiently elevated levels of aeration. Using the proteomics of wild-type and mutant strains affected in the extent of their clumping abilities, we show that cell-to-cell clumping represents a metabolic scavenging strategy that likely prepares the cells for further metabolic stresses. Analysis of mutants affected in carbon or nitrogen metabolism confirmed this assumption. The metabolic changes experienced as clumping progresses prime cells for flocculation, a morphological and metabolic shift of cells triggered under elevated-aeration conditions and nitrogen limitation. The analysis of various mutants during clumping and flocculation characterized an ordered set of changes in cell envelope properties accompanying the metabolic changes. These data also identify clumping and early flocculation to be behaviors compatible with the expression of nitrogen fixation genes, despite the elevated-aeration conditions. Cell-to-cell clumping may thus license diazotrophy to microaerophilic A. brasilense cells under elevated oxygen conditions and prime them for long-term survival via flocculation if metabolic stress persists. PMID:26407887

Functional and Biomimetic Materials for Engineering of the Three-Dimensional Cell Microenvironment.

PubMed

Huang, Guoyou; Li, Fei; Zhao, Xin; Ma, Yufei; Li, Yuhui; Lin, Min; Jin, Guorui; Lu, Tian Jian; Genin, Guy M; Xu, Feng

2017-10-25

The cell microenvironment has emerged as a key determinant of cell behavior and function in development, physiology, and pathophysiology. The extracellular matrix (ECM) within the cell microenvironment serves not only as a structural foundation for cells but also as a source of three-dimensional (3D) biochemical and biophysical cues that trigger and regulate cell behaviors. Increasing evidence suggests that the 3D character of the microenvironment is required for development of many critical cell responses observed in vivo, fueling a surge in the development of functional and biomimetic materials for engineering the 3D cell microenvironment. Progress in the design of such materials has improved control of cell behaviors in 3D and advanced the fields of tissue regeneration, in vitro tissue models, large-scale cell differentiation, immunotherapy, and gene therapy. However, the field is still in its infancy, and discoveries about the nature of cell-microenvironment interactions continue to overturn much early progress in the field. Key challenges continue to be dissecting the roles of chemistry, structure, mechanics, and electrophysiology in the cell microenvironment, and understanding and harnessing the roles of periodicity and drift in these factors. This review encapsulates where recent advances appear to leave the ever-shifting state of the art, and it highlights areas in which substantial potential and uncertainty remain.

Keratinocyte Motility Is Affected by UVA Radiation-A Comparison between Normal and Dysplastic Cells.

PubMed

Niculiţe, Cristina M; Nechifor, Marina T; Urs, Andreea O; Olariu, Laura; Ceafalan, Laura C; Leabu, Mircea

2018-06-07

UVA radiation induces multiple and complex changes in the skin, affecting epidermal cell behavior. This study reports the effects of UVA exposure on normal (HaCaT) and dysplastic (DOK) keratinocytes. The adherence, spreading and proliferation were investigated by time-lapse measurement of cell layer impedance on different matrix proteins. Prior to UVA exposure, the time required for adherence and spreading did not differ significantly for HaCaT and DOK cells, while spreading areas were larger for HaCaT cells. Under UVA exposure, HaCaT and DOK cells behavior differed in terms of movement and proliferation. The cells' ability to cover the denuded surface and individual cell trajectories were recorded by time-lapse videomicroscopy, during wound healing experiments. Dysplastic keratinocytes showed more sensitivity to UVA, exhibiting transient deficiencies in directionality of movement and a delay in re-coating the denuded area. The actin cytoskeleton displayed a cortical organization immediately after irradiation, in both cell lines, similar to mock-irradiated cells. Post-irradiation, DOK cells displayed a better organization of stress fibers, persistent filopodia, and new, stronger focal contacts. In conclusion, after UVA exposure HaCaT and DOK cells showed a different behavior in terms of adherence, spreading, motility, proliferation, and actin cytoskeleton dynamics, with the dyplastic keratinocytes being more sensitive.

The Mechanical Response of Multifunctional Battery Systems

NASA Astrophysics Data System (ADS)

Tsutsui, Waterloo

The current state of the art in the field of the mechanical behavior of electric vehicle (EV) battery cells is limited to quasi-static analysis. The lack of published data in the dynamic mechanical behavior of EV battery cells blinds engineers and scientists with the uncertainty of what to expect when EVs experience such unexpected events as intrusions to their battery systems. To this end, the recent occurrences of several EVs catching fire after hitting road debris even make this topic timelier. In order to ensure the safety of EV battery, it is critical to develop quantitative understanding of battery cell mechanical behavior under dynamic compressive loadings. Specifically, the research focuses on the dynamic mechanical loading effect on the standard "18650" cylindrical lithium-ion battery cells. In the study, the force-displacement and voltage-displacement behavior of the battery cells were analyzed experimentally at two strain rates, two state-of-charges, and two unit-cell configurations. The results revealed the strain rate sensitivity of their mechanical responses with the solid sacrificial elements. When the hollow sacrificial cells are used, on the other hand, effect was negligible up to the point of densification strength. Also, the high state-of-charge appeared to increase the stiffness of the battery cells. The research also revealed the effectiveness of the sacrificial elements on the mechanical behavior of a unit cell that consists of one battery cell and six sacrificial elements. The use of the sacrificial elements resulted in the delayed initiation of electric short circuit. Based on the analysis of battery behavior at the cell level, granular battery assembly, a battery pack, was designed and fabricated. The behavior of the granular battery assembly was analyzed both quasistatically and dynamically. Building on the results of the research, various research plans were proposed. Through conducting the research, we sought to answer the following research questions: Could we use battery cells and packs as a part of vehicle structures? Could we use battery cells and packs as a part of vehicle impact energy absorption structure? Based on the research results, the answer to the first question is "yes." However, the granular battery assembly configuration is not suitable as a load-bearing battery structure since the main purpose of granular battery assembly, apart from energy storage for vehicle propulsion, is to work as a kinetic energy dissipation device. The answer to the second question is also "yes." However, the kinetic energy dissipation is mainly performed by the sacrificial elements surrounding the battery cells.

Embryonic cell-cell adhesion: a key player in collective neural crest migration.

PubMed

Barriga, Elias H; Mayor, Roberto

2015-01-01

Cell migration is essential for morphogenesis, adult tissue remodeling, wound healing, and cancer cell migration. Cells can migrate as individuals or groups. When cells migrate in groups, cell-cell interactions are crucial in order to promote the coordinated behavior, essential for collective migration. Interestingly, recent evidence has shown that cell-cell interactions are also important for establishing and maintaining the directionality of these migratory events. We focus on neural crest cells, as they possess extraordinary migratory capabilities that allow them to migrate and colonize tissues all over the embryo. Neural crest cells undergo an epithelial-to-mesenchymal transition at the same time than perform directional collective migration. Cell-cell adhesion has been shown to be an important source of planar cell polarity and cell coordination during collective movement. We also review molecular mechanisms underlying cadherin turnover, showing how the modulation and dynamics of cell-cell adhesions are crucial in order to maintain tissue integrity and collective migration in vivo. We conclude that cell-cell adhesion during embryo development cannot be considered as simple passive resistance to force, but rather participates in signaling events that determine important cell behaviors required for cell migration. © 2015 Elsevier Inc. All rights reserved.

Regulation of Mammary Stem Cell Quiescence via Post-Translational Modification of DeltaNp63alpha

DTIC Science & Technology

2012-12-01

This document is the Annual Summary Report on the training grant awarded to Andrew DeCastro entitled Regulation of Mammary Stem Cell Quiescence via...screen) mediated phosphorylation of deltaNPdelta3 on stem cell behavior and mitotic activity. Task 1 aims to determine the effects of wild-type, phospho...ablative and phospho-mimetic alleles of deltaNP63delta phosphorylation on stem cell behavior in vitro. Thus far, we demonstrate that stem cell enriched

Immobilization of Heparan Sulfate on Electrospun Meshes to Support Embryonic Stem Cell Culture and Differentiation*

PubMed Central

Meade, Kate A.; White, Kathryn J.; Pickford, Claire E.; Holley, Rebecca J.; Marson, Andrew; Tillotson, Donna; van Kuppevelt, Toin H.; Whittle, Jason D.; Day, Anthony J.; Merry, Catherine L. R.

2013-01-01

As our understanding of what guides the behavior of multi- and pluripotent stem cells deepens, so too does our ability to utilize certain cues to manipulate their behavior and maximize their therapeutic potential. Engineered, biologically functionalized materials have the capacity to influence stem cell behavior through a powerful combination of biological, mechanical, and topographical cues. Here, we present the development of a novel electrospun scaffold, functionalized with glycosaminoglycans (GAGs) ionically immobilized onto the fiber surface. Bound GAGs retained the ability to interact with GAG-binding molecules and, crucially, presented GAG sulfation motifs fundamental to mediating stem cell behavior. Bound GAG proved to be biologically active, rescuing the neural differentiation capacity of heparan sulfate-deficient mouse embryonic stem cells and functioning in concert with FGF4 to facilitate the formation of extensive neural processes across the scaffold surface. The combination of GAGs with electrospun scaffolds creates a biomaterial with potent applicability for the propagation and effective differentiation of pluripotent stem cells. PMID:23235146

Immobilization of heparan sulfate on electrospun meshes to support embryonic stem cell culture and differentiation.

PubMed

Meade, Kate A; White, Kathryn J; Pickford, Claire E; Holley, Rebecca J; Marson, Andrew; Tillotson, Donna; van Kuppevelt, Toin H; Whittle, Jason D; Day, Anthony J; Merry, Catherine L R

2013-02-22

As our understanding of what guides the behavior of multi- and pluripotent stem cells deepens, so too does our ability to utilize certain cues to manipulate their behavior and maximize their therapeutic potential. Engineered, biologically functionalized materials have the capacity to influence stem cell behavior through a powerful combination of biological, mechanical, and topographical cues. Here, we present the development of a novel electrospun scaffold, functionalized with glycosaminoglycans (GAGs) ionically immobilized onto the fiber surface. Bound GAGs retained the ability to interact with GAG-binding molecules and, crucially, presented GAG sulfation motifs fundamental to mediating stem cell behavior. Bound GAG proved to be biologically active, rescuing the neural differentiation capacity of heparan sulfate-deficient mouse embryonic stem cells and functioning in concert with FGF4 to facilitate the formation of extensive neural processes across the scaffold surface. The combination of GAGs with electrospun scaffolds creates a biomaterial with potent applicability for the propagation and effective differentiation of pluripotent stem cells.

T cell deficiency leads to cognitive dysfunction: Implications for therapeutic vaccination for schizophrenia and other psychiatric conditions

PubMed Central

Kipnis, Jonathan; Cohen, Hagit; Cardon, Michal; Ziv, Yaniv; Schwartz, Michal

2004-01-01

The effects of the adaptive immune system on the cognitive performance and abnormal behaviors seen in mental disorders such as schizophrenia have never been documented. Here, we show that mice deprived of mature T cells manifested cognitive deficits and behavioral abnormalities, which were remediable by T cell restoration. T cell-based vaccination, using glatiramer acetate (copolymer-1, a weak agonist of numerous self-reactive T cells), can overcome the behavioral and cognitive abnormalities that accompany neurotransmitter imbalance induced by (+)dizocilpine maleate (MK-801) or amphetamine. The results, by suggesting that peripheral T cell deficit can lead to cognitive and behavioral impairment, highlight the importance of properly functioning adaptive immunity in the maintenance of mental activity and in coping with conditions leading to cognitive deficits. These findings point to critical factors likely to contribute to age- and AIDS-related dementias and might herald the development of a therapeutic vaccination for fighting off cognitive dysfunction and psychiatric conditions. PMID:15141078

Comparing handheld and hands-free cell phone usage behaviors while driving.

PubMed

Soccolich, Susan A; Fitch, Gregory M; Perez, Miguel A; Hanowski, Richard J

2014-01-01

The goal of this study was to compare cell phone usage behaviors while driving across 3 types of cell phones: handheld (HH) cell phones, portable hands-free (PHF) cell phones, and integrated hands-free (IHF) cell phones. Naturalistic driving data were used to observe HH, PHF, and IHF usage behaviors in participants' own vehicles without any instructions or manipulations by researchers. In addition to naturalistic driving data, drivers provided their personal cell phone call records. Calls during driving were sampled and observed in naturalistically collected video. Calls were reviewed to identify cell phone type used for, and duration of, cell phone subtasks, non-cell phone secondary tasks, and other use behaviors. Drivers in the study self-identified as HH, PHF, or IHF users if they reported using that cell phone type at least 50% of the time. However, each sampled call was classified as HH, PHF, or IHF if the talking/listening subtask was conducted using that cell phone type, without considering the driver's self-reported group. Drivers with PHF or IHF systems also used HH cell phones (IHF group used HH cell phone in 53.2% of the interactions, PHF group used HH cell phone for 55.5% of interactions). Talking/listening on a PHF phone or an IHF phone was significantly longer than talking/listening on an HH phone (P <.05). HH dialing was significantly longer in duration than PHF or IHF begin/answer tasks. End phone call task for HH phones was significantly longer in duration than the end phone call task for PHF and IHF phones. Of all the non-cell phone-related secondary tasks, eating or drinking was found to occur significantly more often during IHF subtasks (0.58%) than in HH subtasks (0.15%). Drivers observed to reach for their cell phone mostly kept their cell phone in the cup holder (36.3%) or in their seat or lap (29.0% of interactions); however, some observed locations may have required drivers to move out of position. Hands-free cell phone technologies reduce the duration of cell phone visual-manual tasks compared to handheld cell phones. However, drivers with hands-free cell phone technologies available to them still choose to use handheld cell phones to converse or complete cell phone visual-manual tasks for a noteworthy portion of interactions.

CD11c-Expressing Cells Affect Regulatory T Cell Behavior in the Meninges during Central Nervous System Infection.

PubMed

O'Brien, Carleigh A; Overall, Christopher; Konradt, Christoph; O'Hara Hall, Aisling C; Hayes, Nikolas W; Wagage, Sagie; John, Beena; Christian, David A; Hunter, Christopher A; Harris, Tajie H

2017-05-15

Regulatory T cells (Tregs) play an important role in the CNS during multiple infections, as well as autoimmune inflammation, but the behavior of this cell type in the CNS has not been explored. In mice, infection with Toxoplasma gondii leads to a Th1-polarized parasite-specific effector T cell response in the brain. Similarly, Tregs in the CNS during T. gondii infection are Th1 polarized, as exemplified by their T-bet, CXCR3, and IFN-γ expression. Unlike effector CD4 + T cells, an MHC class II tetramer reagent specific for T. gondii did not recognize Tregs isolated from the CNS. Likewise, TCR sequencing revealed minimal overlap in TCR sequence between effector T cells and Tregs in the CNS. Whereas effector T cells are found in the brain parenchyma where parasites are present, Tregs were restricted to the meninges and perivascular spaces. The use of intravital imaging revealed that activated CD4 + T cells within the meninges were highly migratory, whereas Tregs moved more slowly and were found in close association with CD11c + cells. To test whether the behavior of Tregs in the meninges is influenced by interactions with CD11c + cells, mice were treated with anti-LFA-1 Abs to reduce the number of CD11c + cells in this space. The anti-LFA-1 treatment led to fewer contacts between Tregs and the remaining CD11c + cells and increased the speed of Treg migration. These data suggest that Tregs are anatomically restricted within the CNS, and their interaction with CD11c + populations regulates their local behavior during T. gondii infection. Copyright © 2017 by The American Association of Immunologists, Inc.

Classification of human natural killer cells based on migration behavior and cytotoxic response.

PubMed

Vanherberghen, Bruno; Olofsson, Per E; Forslund, Elin; Sternberg-Simon, Michal; Khorshidi, Mohammad Ali; Pacouret, Simon; Guldevall, Karolin; Enqvist, Monika; Malmberg, Karl-Johan; Mehr, Ramit; Önfelt, Björn

2013-02-21

Despite intense scrutiny of the molecular interactions between natural killer (NK) and target cells, few studies have been devoted to dissection of the basic functional heterogeneity in individual NK cell behavior. Using a microchip-based, time-lapse imaging approach allowing the entire contact history of each NK cell to be recorded, in the present study, we were able to quantify how the cytotoxic response varied between individual NK cells. Strikingly, approximately half of the NK cells did not kill any target cells at all, whereas a minority of NK cells was responsible for a majority of the target cell deaths. These dynamic cytotoxicity data allowed categorization of NK cells into 5 distinct classes. A small but particularly active subclass of NK cells killed several target cells in a consecutive fashion. These "serial killers" delivered their lytic hits faster and induced faster target cell death than other NK cells. Fast, necrotic target cell death was correlated with the amount of perforin released by the NK cells. Our data are consistent with a model in which a small fraction of NK cells drives tumor elimination and inflammation.

Short-term desensitization of fast escape behavior associated with suppression of Mauthner cell activity in larval zebrafish.

PubMed

Takahashi, Megumi; Inoue, Maya; Tanimoto, Masashi; Kohashi, Tsunehiko; Oda, Yoichi

2017-08-01

Escape is among the simplest animal behaviors employed to study the neural mechanisms underlying learning. Teleost fishes exhibit behavioral learning of fast escape initiated with a C-shaped body bend (C-start). C-starts are subdivided into short-latency (SLC) and long-latency (LLC) types in larval zebrafish. Whether these two can be separately modified, and the neural correlates of this modification, however, remains undetermined. We thus performed Ca 2+ imaging of Mauthner (M-) cells, a pair of giant hindbrain neurons constituting a core element of SLC circuit, during behavioral learning in larval zebrafish. The Ca 2+ response corresponding to a single spiking of the M-cells was coupled with SLCs but not LLCs. Conditioning with a repeated weak sound at subthreshold intensity to elicit C-starts selectively suppressed SLC occurrence for 10min without affecting LLC responsiveness. The short-term desensitization of SLC was associated with the suppression of M-cell activity, suggesting that changes in single neuron responsiveness mediate behavioral learning. The conditioning did not affect the acoustically evoked mechanotransduction of inner ear hair cells, further suggesting plastic change in transmission efficacy within the auditory input circuit between the hair cells and the M-cell. Copyright © 2017 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

Fos Expression in Monoaminergic Cell Groups in Response to Sociosexual Interactions in Male and Female Japanese Quail

PubMed Central

Iyilikci, Onur; Baxter, Samantha; Balthazart, Jacques; Ball, Gregory F.

2014-01-01

Monoaminergic neurotransmitters regulate different components of sexual behaviors, but how the different monoaminergic cell groups selectively regulate these behaviors is not well understood. We examined the potential contribution of these different cell groups in the control of different aspects of sexual behaviors in male and female quail. We used double-label immunohistochemistry, labeling the protein product of the immediate early gene, Fos, along with tyrosine hydroxylase (TH) or tryptophan hydroxylase (TPH), markers for catecholaminergic or indolaminergic cells, respectively. Rhythmic Cloacal Sphincter Movements (RCSM) were recorded as a measure of male appetitive sexual behavior. Consummatory sexual behaviors were evaluated based on the species-typical copulation sequence. Enhanced Fos expression in the medial preoptic nucleus and bed nucleus of the stria terminalis was observed in association with both physical and visual contact to the opposite sex for males, but not for females. Fos induction associated with physical contact was observed in the ventral tegmental area and anterior periaqueductal gray in both sexes. In males only, the number of Fos-immunoreactive (ir) cells increased in the visual contact condition in these two dopaminergic cell groups, however no significant effect was observed for double-labeled TH-Fos-ir cells. In addition, consummatory but not appetitive sexual behavior increased Fos expression in TPH-ir cells in the raphe pallidus of males. This increase following physical but not visual contact agrees with the notion that activation of the serotoninergic system is implicated in the development of sexual satiation but not activated by simply viewing a female, in contrast to the dopaminergic system. PMID:24512065

Cell shape characterization and classification with discrete Fourier transforms and self-organizing maps.

PubMed

Kriegel, Fabian L; Köhler, Ralf; Bayat-Sarmadi, Jannike; Bayerl, Simon; Hauser, Anja E; Niesner, Raluca; Luch, Andreas; Cseresnyes, Zoltan

2018-03-01

Cells in their natural environment often exhibit complex kinetic behavior and radical adjustments of their shapes. This enables them to accommodate to short- and long-term changes in their surroundings under physiological and pathological conditions. Intravital multi-photon microscopy is a powerful tool to record this complex behavior. Traditionally, cell behavior is characterized by tracking the cells' movements, which yields numerous parameters describing the spatiotemporal characteristics of cells. Cells can be classified according to their tracking behavior using all or a subset of these kinetic parameters. This categorization can be supported by the a priori knowledge of experts. While such an approach provides an excellent starting point for analyzing complex intravital imaging data, faster methods are required for automated and unbiased characterization. In addition to their kinetic behavior, the 3D shape of these cells also provide essential clues about the cells' status and functionality. New approaches that include the study of cell shapes as well may also allow the discovery of correlations amongst the track- and shape-describing parameters. In the current study, we examine the applicability of a set of Fourier components produced by Discrete Fourier Transform (DFT) as a tool for more efficient and less biased classification of complex cell shapes. By carrying out a number of 3D-to-2D projections of surface-rendered cells, the applied method reduces the more complex 3D shape characterization to a series of 2D DFTs. The resulting shape factors are used to train a Self-Organizing Map (SOM), which provides an unbiased estimate for the best clustering of the data, thereby characterizing groups of cells according to their shape. We propose and demonstrate that such shape characterization is a powerful addition to, or a replacement for kinetic analysis. This would make it especially useful in situations where live kinetic imaging is less practical or not possible at all. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

spadetail-dependent cell compaction of the dorsal zebrafish blastula.

PubMed

Warga, R M; Nüsslein-volhard, C

1998-11-01

The dorsal marginal zone of the zebrafish blastula, equivalent to the amphibian Spemann organizer, is destined to become the tissues of the notochord and prechordal plate. Preceding gastrulation in the zebrafish, we find that these future mesendodermal cells acquire a cohesive cell behavior characterized by flattening and maximization of intercellular contacts, somewhat resembling cell compaction in mouse blastocysts. This behavior may suppress cell intermingling. Surprisingly, this blastula cell compaction requires normal function of spadetail, a gene known to be necessary for the dorsal convergent cell movement of paraxial mesoderm later in the gastrula. We propose that spadetail-dependent cell compaction subtly controls the early mixing and dispersal of dorsal cells that coalesce into the prospective organizer region. This early process may be necessary for the correct location of the boundary separating axial and paraxial cells. Copyright 1998 Academic Press.

Turning behaviors of T cells climbing up ramp-like structures are regulated by myosin light chain kinase activity and lamellipodia formation.

PubMed

Song, Kwang Hoon; Lee, Jaehyun; Jung, Hong-Ryul; Park, HyoungJun; Doh, Junsang

2017-09-14

T cells navigate diverse microenvironments to perform immune responses. Micro-scale topographical structures within the tissues, which may inherently exist in normal tissues or may be formed by inflammation or injury, can influence T cell migration, but how T cell migration is affected by such topographical structures have not been investigated. In this study, we fabricated ramp-like structures with a 5 μm height and various slopes, and observed T cells climbing up the ramp-like structures. T cells encountering the ramp-like structures exhibited MLC accumulation near head-tail junctions contacting the ramp-like structures, and made turns to the direction perpendicular to the ramp-like structures. Pharmacological study revealed that lamellipodia formation mediated by arp2/3 and contractility regulated by myosin light chain kinase (MLCK) were responsible for the intriguing turning behavior of T cells climbing the ramp-like structures. Arp2/3 or MLCK inhibition substantially reduced probability of T cells climbing sharp-edged ramp-like structures, indicating intriguing turning behavior of T cells mediated by lamellipodia formation and MLCK activity may be important for T cells to access inflamed or injured tissues with abrupt topographical changes.

Evaluation of the shear force of single cancer cells by vertically aligned carbon nanotubes suitable for metastasis diagnosis.

PubMed

Abdolahad, M; Mohajerzadeh, S; Janmaleki, M; Taghinejad, H; Taghinejad, M

2013-03-01

Vertically aligned carbon nanotube (VACNT) arrays have been demonstrated as probes for rapid quantifying of cancer cell deformability with high resolution. Through entrapment of various cancer cells on CNT arrays, the deflections of the nanotubes during cell deformation were used to derive the lateral cell shear force using a large deflection mode method. It is observed that VACNT beams act as sensitive and flexible agents, which transfer the shear force of cells trapped on them by an observable deflection. The metastatic cancer cells have significant deformable structures leading to a further cell traction force (CTF) than primary cancerous one on CNT arrays. The elasticity of different cells could be compared by their CTF measurement on CNT arrays. This study presents a nanotube-based methodology for quantifying the single cell mechanical behavior, which could be useful for understanding the metastatic behavior of cells.

Collective Behavior of Brain Tumor Cells: the Role of Hypoxia

NASA Astrophysics Data System (ADS)

Khain, Evgeniy; Katakowski, Mark; Hopkins, Scott; Szalad, Alexandra; Zheng, Xuguang; Jiang, Feng; Chopp, Michael

2013-03-01

We consider emergent collective behavior of a multicellular biological system. Specifically we investigate the role of hypoxia (lack of oxygen) in migration of brain tumor cells. We performed two series of cell migration experiments. The first set of experiments was performed in a typical wound healing geometry: cells were placed on a substrate, and a scratch was done. In the second set of experiments, cell migration away from a tumor spheroid was investigated. Experiments show a controversy: cells under normal and hypoxic conditions have migrated the same distance in the ``spheroid'' experiment, while in the ``scratch'' experiment cells under normal conditions migrated much faster than under hypoxic conditions. To explain this paradox, we formulate a discrete stochastic model for cell dynamics. The theoretical model explains our experimental observations and suggests that hypoxia decreases both the motility of cells and the strength of cell-cell adhesion. The theoretical predictions were further verified in independent experiments.

Dim-light sensitivity of cells in the awake cat's lateral geniculate and medial interlaminar nuclei: a correlation with behavior.

PubMed

Kang, Incheol; Malpeli, Joseph G

2009-08-01

Contrast thresholds of cells in the dorsal lateral geniculate (LGNd) and medial interlaminar (MIN) nuclei of awake cats were measured for scotopic and mesopic vision with drifting sine gratings (1/8, 2, and 4 cycles/deg [cpd]; 4-Hz temporal frequency). Thresholds for mean firing rate (F0) and temporally modulated responses (F1) were derived with receiver-operating-characteristic analyses and compared with behavioral measures recently reported by Kang and colleagues. Behavioral sensitivity was predicted by the neural responses of the most sensitive combinations of cell class and response mode: Y-cell F1 responses for 1/8 cpd, X-cell F1 responses for 2 cpd, and Y-cell F0 responses for 4 cpd. All previous estimates of neural scotopic increment thresholds in animal models fell between Weber's law (proportional to retinal illuminance) and the deVries-Rose law (proportional to the square root of illuminance). However, psychophysical experiments suggest that under appropriate conditions human scotopic vision follows the deVries-Rose law. If behavioral sensitivity is assumed to be determined by the most sensitive class of cells, this discrepancy is resolved. Under scotopic conditions, off-center Y cells were the most sensitive and these followed the deVries-Rose law fairly closely. MIN Y cells were, on average, 0.25 log units more sensitive than LGNd Y cells under scotopic conditions, supporting a previous proposal that the MIN is a specialization of the carnivore for dim-light vision. We conclude that both physiologically and behaviorally, cat and human scotopic vision are fundamentally similar, including adherence to the deVries-Rose law for detection of Gabor functions.

Two photon microscopy intravital study of DC-mediated anti-tumor response of NK cells

NASA Astrophysics Data System (ADS)

Caccia, Michele; Gorletta, Tatiana; Sironi, Laura; Zanoni, Ivan; Salvetti, Cristina; Collini, Maddalena; Granucci, Francesca; Chirico, Giuseppe

2010-02-01

Recent studies have demonstrated that dendritic cells (DCs) play a crucial role in the activation of Natural Killer cells (NKs) that are responsible for anti-tumor innate immune responses. The focus of this report is on the role of pathogen associated molecular pattern (PAMP) activated-DCs in inducing NK cell-mediated anti-tumor responses. Mice transplanted sub-cute (s.c.) with AK7 cells, a mesothelioma cell line sensitive to NK cell responses, are injected with fluorescent NK cells and DC activation is then induced by s.c. injection of Lipopolysaccharide (LPS). Using 4 dimensional tracking we follow the kinetic behavior of NK cells at the Draining Lymph-Node (DLN). As control, noninflammatory conditions are also evaluated. Our data suggest that NK cells are recruited to the DLN where they can interact with activated-DCs with a peculiar kinetic behavior: short lived interactions interleaved by rarer longer ones. We also found that the changes in the NK dynamic behavior in inflammatory conditions clearly affect relevant motility parameters such as the instantaneous and average velocity and the effective diffusion coefficient. This observation suggests that NK cells and activated-DCs might efficiently interact in the DLN, where cells could be activated. Therefore the interaction between activated-DCs and NK cells in DLN is not only a reality but it may be also crucial for the start of the immune response of the NKs.

Dissection of Drosophila Visual Circuits Implicative in Figure Motion

NASA Astrophysics Data System (ADS)

Kelley, Ross G.

The Drosophila visual system offers a model to study the foundations of how motion signals are computed from raw visual input and transformed into behavioral output. My studies focus on how specific cells in the Drosophila nervous system implement this input-output transformation. The individual cell types are known from classical studies using Golgi impregnations, but the assembly of motion processing circuits and the behavioral outputs remain poorly understood. Using an electronic flight simulator for flies and a white-noise analysis developed by Aptekar et al., I screen specific neurons in the optic lobes for behavioral ramifications. This approach produces wing responses to both the spatial and temporal dynamics of motion signals. The results of these experiments give Spatiotemporal Action Fields (STAFs) across the entire visual panorama. Genetically inactivating a distinct grouping of cells in the third optic ganglion, the Lobula Plate, the Horizontal System (HS) cell group, produced a robust phenotype through STAF analysis. Using the Gal4-UAS transgene expression system, we selectively inactivated the HS cells by expressing in their membrane inward rectifying potassium channels (Kir2.1) to hyperpolarize these cells, preventing their role in synaptic signaling. The results of the experiments show mutants lose steering responses to several distinct categories of figure motion and reduced behavioral responses to figure motion set against a contrasting moving background, highlighting their role in figure tracking behavior. Finally, a synapse inactivating protein, tetanus toxin (TNT), expressed in the HS cell group, produces a different behavioral phenotype than overexpressing inward rectifier. TNT, a bacterial neurotoxin, cleaves SNARE proteins resulting in loss of synaptic output of the cell, but the dendrites are intact and signal normally, preserving dendro-dendritic interactions known to sculpt the visual receptive fields of these cells. The two distinct phenotypes to each genetically targeted silencer differentiate the functional role of dendritic integration versus axonal output in this important cell group.

Collective Motion in Bacterial Populations with Mixed Phenotypic Behaviors

NASA Astrophysics Data System (ADS)

Hoeger, Kentaro; Strickland, Ben; Shoup, Daniel; Ursell, Tristan

The motion of large, densely packed groups of organisms is often qualitatively distinct from the motion of individuals, yet hinges on individual properties and behaviors. Collective motion of bacteria depends strongly on the phenotypic behaviors of individual cells, the physical interactions between cells, and the geometry of their environment, often with multiple phenotypes coexisting in a population. Thus, to characterize how these selectively important interactions affect group traits, such as cell dispersal, spatial segregation of phenotypes, and material transport in groups, we use a library of Bacillus subtilis mutants that modulate chemotaxis, motility, and biofilm formation. By mixing phenotypes and observing bacterial behaviors and motion at single cell resolution, we probe collective motion as a function of phenotypic mixture and environmental geometry. Our work demonstrates that collective microbial motion exhibits a transition, from `turbulence' to semiballistic burrowing, as phenotypic composition varies. This work illuminates the role that individual cell behaviors play in the emergence of collective motion, and may signal qualitatively distinct regimes of material transport in bacterial populations. University of Oregon.

Live Imaging of Cell Motility and Actin Cytoskeleton of Individual Neurons and Neural Crest Cells in Zebrafish Embryos

PubMed Central

Andersen, Erica; Asuri, Namrata; Clay, Matthew; Halloran, Mary

2010-01-01

The zebrafish is an ideal model for imaging cell behaviors during development in vivo. Zebrafish embryos are externally fertilized and thus easily accessible at all stages of development. Moreover, their optical clarity allows high resolution imaging of cell and molecular dynamics in the natural environment of the intact embryo. We are using a live imaging approach to analyze cell behaviors during neural crest cell migration and the outgrowth and guidance of neuronal axons. Live imaging is particularly useful for understanding mechanisms that regulate cell motility processes. To visualize details of cell motility, such as protrusive activity and molecular dynamics, it is advantageous to label individual cells. In zebrafish, plasmid DNA injection yields a transient mosaic expression pattern and offers distinct benefits over other cell labeling methods. For example, transgenic lines often label entire cell populations and thus may obscure visualization of the fine protrusions (or changes in molecular distribution) in a single cell. In addition, injection of DNA at the one-cell stage is less invasive and more precise than dye injections at later stages. Here we describe a method for labeling individual developing neurons or neural crest cells and imaging their behavior in vivo. We inject plasmid DNA into 1-cell stage embryos, which results in mosaic transgene expression. The vectors contain cell-specific promoters that drive expression of a gene of interest in a subset of sensory neurons or neural crest cells. We provide examples of cells labeled with membrane targeted GFP or with a biosensor probe that allows visualization of F-actin in living cells1. Erica Andersen, Namrata Asuri, and Matthew Clay contributed equally to this work. PMID:20130524

Engineering three-dimensional cell mechanical microenvironment with hydrogels.

PubMed

Huang, Guoyou; Wang, Lin; Wang, Shuqi; Han, Yulong; Wu, Jinhui; Zhang, Qiancheng; Xu, Feng; Lu, Tian Jian

2012-12-01

Cell mechanical microenvironment (CMM) significantly affects cell behaviors such as spreading, migration, proliferation and differentiation. However, most studies on cell response to mechanical stimulation are based on two-dimensional (2D) planar substrates, which cannot mimic native three-dimensional (3D) CMM. Accumulating evidence has shown that there is a significant difference in cell behavior in 2D and 3D microenvironments. Among the materials used for engineering 3D CMM, hydrogels have gained increasing attention due to their tunable properties (e.g. chemical and mechanical properties). In this paper, we provide an overview of recent advances in engineering hydrogel-based 3D CMM. Effects of mechanical cues (e.g. hydrogel stiffness and externally induced stress/strain in hydrogels) on cell behaviors are described. A variety of approaches to load mechanical stimuli in 3D hydrogel-based constructs are also discussed.

Secondary Behavior of Drivers on Cell Phones.

PubMed

Farmer, Charles M; Klauer, Sheila G; McClafferty, Julie A; Guo, Feng

2015-01-01

The objective of this study was to determine whether cell phone use by drivers leads to changes in the frequency of other types of potentially distracting behavior. There were 2 main questions of interest: (1) As each driver changes cell phone use, does he or she change the amount of driving time spent on other distracting behavior? (2) As each driver changes cell phone use, does he or she change the amount of driving time spent looking away from the driving task? Day-to-day driving behavior of 105 volunteer subjects was monitored over a period of 1 year. The amount of driving time during each trip spent on tasks secondary to driving (or looking away from the driving task) was correlated to the amount of time on a cell phone, taking into account the relationships among trips taken by the same driver. Drivers spent 42% of the time engaging in at least one secondary activity. Drivers were talking on a cell phone 7% of the time, interacting in some other way with a cell phone 5% of the time, and engaging in some other secondary activity (sometimes in conjunction with cell phone use) 33% of the time. Other than cell phone use, the most common secondary activities were interacting with a passenger (12% of driving time), holding but not otherwise interacting with an object (6%), and talking/singing/dancing to oneself (5%). Drivers were looking straight forward 81% of the time, forward left or right 5% of time, in a mirror 4% of the time, and elsewhere (eyes off driving task) 10% of time. On average, for each 1 percentage point increase in cell phone talking, the other secondary behavior rate decreased by 0.28 percentage points (P <.0001), and the rate of eyes off driving task decreased by 0.02 percentage points (P =.0067). For each 1 percentage point increase in the amount of other cell phone interaction per trip, the other secondary behavior rate decreased by 0.08 percentage points (P =.0558), but the rate of eyes off driving task increased by 0.06 percentage points (P <.0001). Although using a cell phone can be distracting from the driving task, other secondary activities can be equally or more distracting, at least as measured by eye glances away from the road ahead and mirrors. In this group of drivers, dialing, reaching for, and answering the cell phone were associated with increased eyes off driving task, as opposed to the decrease in eyes off driving task associated with talking on the phone. Predictions about the effect of cell phone usage on driver distraction need to consider what other behavior is being displaced by the time spent on the phone. A focus by researchers, policy-makers, and the media on the distraction of using cell phones while driving may lead drivers to disregard the risk of other secondary behavior that is even more distracting.

Optical micromanipulation of active cells with minimal perturbations: direct and indirect pushing.

PubMed

Wang, Chenlu; Chowdhury, Sagar; Gupta, Satyandra K; Losert, Wolfgang

2013-04-01

The challenge to wide application of optical tweezers in biological micromanipulation is the photodamage caused by high-intensity laser exposure to the manipulated living systems. While direct exposure to infrared lasers is less likely to kill cells, it can affect cell behavior and signaling. Pushing cells with optically trapped objects has been introduced as a less invasive alternative, but the technique includes some exposure of the biological object to parts of the optical tweezer beam. To keep the cells farther away from the laser, we introduce an indirect pushing-based technique for noninvasive manipulation of sensitive cells. We compare how cells respond to three manipulation approaches: direct manipulation, pushing, and indirect pushing. We find that indirect manipulation techniques lessen the impact of manipulation on cell behavior. Cell survival increases, as does the ability of cells to maintain shape and wiggle. Our experiments also demonstrate that indirect pushing allows cell-cell contacts to be formed in a controllable way, while retaining the ability of cells to change shape and move.

Intracarotid injection of fluorescence activated cell-sorted CD49d-positive neural stem cells improves targeted cell delivery and behavior after stroke in a mouse stroke model.

PubMed

Guzman, Raphael; De Los Angeles, Alejandro; Cheshier, Samuel; Choi, Raymond; Hoang, Stanley; Liauw, Jason; Schaar, Bruce; Steinberg, Gary

2008-04-01

Intravascular delivery of neural stem cells (NSCs) after stroke has been limited by the low efficiency of transendothelial migration. Vascular cell adhesion molecule-1 is an endothelial adhesion molecule known to be upregulated early after stroke and is responsible for the firm adhesion of inflammatory cells expressing the surface integrin, CD49d. We hypothesize that enriching for NSCs that express CD49d and injecting them into the carotid artery would improve targeted cell delivery to the injured brain. Mouse NSCs were analyzed for the expression of CD49d by fluorescence activated cell sorting. A CD49d-enriched (CD49d(+)) (>95%) and -depleted (CD49d(-); <5%) NSC population was obtained by cell sorting. C57/Bl6 mice underwent left-sided hypoxia-ischemia surgery and were assigned to receive 3 x 10(5) CD49d(+), CD49d(-) NSCs, or vehicle injection into the left common carotid artery 48 hours after stroke. Behavioral recovery was measured using a rotarod for 2 weeks after cell injection. Fluorescence activated cell sorting analysis revealed 25% CD49d(+) NSCs. In a static adhesion assay, NSCs adhered to vascular cell adhesion molecule-1 in a dose-dependent manner. Significantly more NSCs were found in the cortex, the hippocampus, and the subventricular zone in the ischemic hemisphere in animals receiving CD49d(+) NSCs as compared with CD49d(-) NSCs (P<0.05). Animals treated with CD49d(+) cells showed a significantly better behavioral recovery as compared with CD49d(-) and vehicle-treated animals. We show that enrichment of NSCs by fluorescence activated cell sorting for the surface integrin, CD49d, and intracarotid delivery promotes cell homing to the area of stroke in mice and improves behavioral recovery.

Incorporating pushing in exclusion-process models of cell migration.

PubMed

Yates, Christian A; Parker, Andrew; Baker, Ruth E

2015-05-01

The macroscale movement behavior of a wide range of isolated migrating cells has been well characterized experimentally. Recently, attention has turned to understanding the behavior of cells in crowded environments. In such scenarios it is possible for cells to interact, inducing neighboring cells to move in order to make room for their own movements or progeny. Although the behavior of interacting cells has been modeled extensively through volume-exclusion processes, few models, thus far, have explicitly accounted for the ability of cells to actively displace each other in order to create space for themselves. In this work we consider both on- and off-lattice volume-exclusion position-jump processes in which cells are explicitly allowed to induce movements in their near neighbors in order to create space for themselves to move or proliferate into. We refer to this behavior as pushing. From these simple individual-level representations we derive continuum partial differential equations for the average occupancy of the domain. We find that, for limited amounts of pushing, comparison between the averaged individual-level simulations and the population-level model is nearly as good as in the scenario without pushing. Interestingly, we find that, in the on-lattice case, the diffusion coefficient of the population-level model is increased by pushing, whereas, for the particular off-lattice model that we investigate, the diffusion coefficient is reduced. We conclude, therefore, that it is important to consider carefully the appropriate individual-level model to use when representing complex cell-cell interactions such as pushing.

Iterative design of peptide-based hydrogels and the effect of network electrostatics on primary chondrocyte behavior

PubMed Central

Sinthuvanich, Chomdao; Haines-Butterick, Lisa A.; Nagy, Katelyn J.; Schneider, Joel P.

2012-01-01

Iterative peptide design was used to generate two peptide-based hydrogels to study the effect of network electrostatics on primary chondrocyte behavior. MAX8 and HLT2 peptides have formal charge states of +7 and +5 per monomer, respectively. These peptides undergo triggered folding and self-assembly to afford hydrogel networks having similar rheological behavior and local network morphologies, yet different electrostatic character. Each gel can be used to directly encapsulate and syringe-deliver cells. The influence of network electrostatics on cell viability after encapsulation and delivery, extracellular matrix deposition, gene expression, and the bulk mechanical properties of the gel-cell constructs as a function of culture time was assessed. The less electropositive HLT2 gel provides a microenvironment more conducive to chondrocyte encapsulation, delivery, and phenotype maintenance. Cell viability was higher for this gel and although a moderate number of cells dedifferentiated to a fibroblast-like phenotype, many retained their chondrocytic behavior. As a result, gel-cell constructs prepared with HLT2, cultured under static in vitro conditions, contained more GAG and type II collagen resulting in mechanically superior constructs. Chondrocytes delivered in the more electropositive MAX8 gel experienced a greater degree of cell death during encapsulation and delivery and the remaining viable cells were less prone to maintain their phenotype. As a result, MAX8 gel-cell constructs had fewer cells, of which a limited number were capable of laying down cartilage-specific ECM. PMID:22841922

Iterative design of peptide-based hydrogels and the effect of network electrostatics on primary chondrocyte behavior.

PubMed

Sinthuvanich, Chomdao; Haines-Butterick, Lisa A; Nagy, Katelyn J; Schneider, Joel P

2012-10-01

Iterative peptide design was used to generate two peptide-based hydrogels to study the effect of network electrostatics on primary chondrocyte behavior. MAX8 and HLT2 peptides have formal charge states of +7 and +5 per monomer, respectively. These peptides undergo triggered folding and self-assembly to afford hydrogel networks having similar rheological behavior and local network morphologies, yet different electrostatic character. Each gel can be used to directly encapsulate and syringe-deliver cells. The influence of network electrostatics on cell viability after encapsulation and delivery, extracellular matrix deposition, gene expression, and the bulk mechanical properties of the gel-cell constructs as a function of culture time was assessed. The less electropositive HLT2 gel provides a microenvironment more conducive to chondrocyte encapsulation, delivery, and phenotype maintenance. Cell viability was higher for this gel and although a moderate number of cells dedifferentiated to a fibroblast-like phenotype, many retained their chondrocytic behavior. As a result, gel-cell constructs prepared with HLT2, cultured under static in vitro conditions, contained more GAG and type II collagen resulting in mechanically superior constructs. Chondrocytes delivered in the more electropositive MAX8 gel experienced a greater degree of cell death during encapsulation and delivery and the remaining viable cells were less prone to maintain their phenotype. As a result, MAX8 gel-cell constructs had fewer cells, of which a limited number were capable of laying down cartilage-specific ECM. Published by Elsevier Ltd.

Nanochips of Tantalum Oxide Nanodots as artificial-microenvironments for monitoring Ovarian cancer progressiveness

NASA Astrophysics Data System (ADS)

Dhawan, Udesh; Wang, Ssu-Meng; Chu, Ying Hao; Huang, Guewha S.; Lin, Yan Ren; Hung, Yao Ching; Chen, Wen Liang

2016-08-01

Nanotopography modulates cell characteristics and cell behavior. Nanotopological cues can be exploited to investigate the in-vivo modulation of cell characteristics by the cellular microenvironment. However, the studies explaining the modulation of tumor cell characteristics and identifying the transition step in cancer progressiveness are scarce. Here, we engineered nanochips comprising of Tantalum oxide nanodot arrays of 10, 50, 100 and 200 nm as artificial microenvironments to study the modulation of cancer cell behavior. Clinical samples of different types of Ovarian cancer at different stages were obtained, primary cultures were established and then seeded on different nanochips. Immunofluorescence (IF) was performed to compare the morphologies and cell characteristics. Indices corresponding to cell characteristics were defined. A statistical comparison of the cell characteristics in response to the nanochips was performed. The cells displayed differential growth parameters. Morphology, Viability, focal adhesions, microfilament bundles and cell area were modulated by the nanochips which can be used as a measure to study the cancer progressiveness. The ease of fabrication of nanochips ensures mass-production. The ability of the nanochips to act as artificial microenvironments and modulate cell behavior may lead to further prospects in the markerless monitoring of the progressiveness and ultimately, improving the prognosis of Ovarian cancer.

Morphogenesis of the caenorhabditis elegans vulva.

PubMed

Schindler, Adam J; Sherwood, David R

2013-01-01

Understanding how cells move, change shape, and alter cellular behaviors to form organs, a process termed morphogenesis, is one of the great challenges of developmental biology. Formation of the Caenorhabditis elegans vulva is a powerful, simple, and experimentally accessible model for elucidating how morphogenetic processes produce an organ. In the first step of vulval development, three epithelial precursor cells divide and differentiate to generate 22 cells of 7 different vulval subtypes. The 22 vulval cells then rearrange from a linear array into a tube, with each of the seven cell types undergoing characteristic morphogenetic behaviors that construct the vulva. Vulval morphogenesis entails many of the same cellular activities that underlie organogenesis and tissue formation across species, including invagination, lumen formation, oriented cell divisions, cell–cell adhesion, cell migration, cell fusion, extracellular matrix remodeling, and cell invasion. Studies of vulval development have led to pioneering discoveries in a number of these processes and are beginning to bridge the gap between the pathways that specify cells and their connections to morphogenetic behaviors. The simplicity of the vulva and the experimental tools available in C. elegans will continue to make vulval morphogenesis a powerful paradigm to further our understanding of the largely mysterious mechanisms that build tissues and organs. © 2012 Wiley Periodicals, Inc.

Cell phone users, reported crash risk, unsafe driving behaviors and dispositions: a survey of motorists in Maryland.

PubMed

Beck, Kenneth H; Yan, Fang; Wang, Min Qi

2007-01-01

The purpose of this investigation was to identify risky driving behaviors and dispositions that distinguish drivers who use a cell phone while operating a motor vehicle from non-cell phone using drivers. Annual telephone surveys were used to identify drivers who reported using a cell phone while driving in the last month (n=1803) and were compared to those who said they did not use cell phones while driving (n=1578). Cell phone using drivers were more likely to report driving while drowsy, going 20 mph over the speed limit, driving aggressively, running a stop sign or red light, and driving after having had several drinks. They were also more likely to have had a prior history of citation and crash involvement than non-cell phone using drivers. Cell phone using drivers also reported they were less careful and more in a hurry when they drive than non-cell phone using drivers. Cell phone using drivers report engaging in many behaviors that place them at risk for a traffic crash, independent of the specific driving impairments that cell phone usage may produce. Strategies that combine coordinated and sustained enforcement activities along with widespread public awareness campaigns hold promise as effective countermeasures for these drivers, who resemble aggressive drivers in many respects.

Effect of NASA advanced designs on thermal behavior of Ni-H2 cells

NASA Technical Reports Server (NTRS)

Gonzalez-Sanabria, Olga D.

1987-01-01

As part of an overall effort to advance the technology of nickel-hydrogen batteries for low Earth orbit (LEO) applications, advanced designs for individual pressure vessel (IPV) nickel-hydrogen cells have been conceived. These designs incorporate alternative methods of oxygen recombination which affect the thermal behavior of the cells. The effect of these oxygen recombination methods on the cell temperature profiles is examined.

Effect of NASA advanced designs on thermal behavior of Ni-H2 cells

NASA Technical Reports Server (NTRS)

Gonzalez-Sanabria, Olga D.

1988-01-01

As part of an overall effort to advance the technology of nickel-hydrogen batteries for low earth orbit (LEO) applications, advanced designs for individual pressure vessel (IPV) nickel-hydrogen cells have been conceived. These designs incorporate alternative methods of oxygen recombination which affect the thermal behavior of the cells. The effect of these oxygen recombination methods on the cell temperature profiles will be examined.

Cell-type-specific role for nucleus accumbens neuroligin-2 in depression and stress susceptibility.

PubMed

Heshmati, Mitra; Aleyasin, Hossein; Menard, Caroline; Christoffel, Daniel J; Flanigan, Meghan E; Pfau, Madeline L; Hodes, Georgia E; Lepack, Ashley E; Bicks, Lucy K; Takahashi, Aki; Chandra, Ramesh; Turecki, Gustavo; Lobo, Mary Kay; Maze, Ian; Golden, Sam A; Russo, Scott J

2018-01-30

Behavioral coping strategies are critical for active resilience to stress and depression; here we describe a role for neuroligin-2 (NLGN-2) in the nucleus accumbens (NAc). Neuroligins (NLGN) are a family of neuronal postsynaptic cell adhesion proteins that are constituents of the excitatory and inhibitory synapse. Importantly, NLGN-3 and NLGN-4 mutations are strongly implicated as candidates underlying the development of neuropsychiatric disorders with social disturbances such as autism, but the role of NLGN-2 in neuropsychiatric disease states is unclear. Here we show a reduction in NLGN-2 gene expression in the NAc of patients with major depressive disorder. Chronic social defeat stress in mice also decreases NLGN-2 selectively in dopamine D1-positive cells, but not dopamine D2-positive cells, within the NAc of stress-susceptible mice. Functional NLGN-2 knockdown produces bidirectional, cell-type-specific effects: knockdown in dopamine D1-positive cells promotes subordination and stress susceptibility, whereas knockdown in dopamine D2-positive cells mediates active defensive behavior. These findings establish a behavioral role for NAc NLGN-2 in stress and depression; provide a basis for targeted, cell-type specific therapy; and highlight the role of active behavioral coping mechanisms in stress susceptibility.

In vitro electrochemical corrosion and cell viability studies on nickel-free stainless steel orthopedic implants.

PubMed

Salahinejad, Erfan; Hadianfard, Mohammad Jafar; Macdonald, Digby Donald; Sharifi-Asl, Samin; Mozafari, Masoud; Walker, Kenneth J; Rad, Armin Tahmasbi; Madihally, Sundararajan V; Tayebi, Lobat

2013-01-01

The corrosion and cell viability behaviors of nanostructured, nickel-free stainless steel implants were studied and compared with AISI 316L. The electrochemical studies were conducted by potentiodynamic polarization and electrochemical impedance spectroscopic measurements in a simulated body fluid. Cytocompatibility was also evaluated by the adhesion behavior of adult human stem cells on the surface of the samples. According to the results, the electrochemical behavior is affected by a compromise among the specimen's structural characteristics, comprising composition, density, and grain size. The cell viability is interpreted by considering the results of the electrochemical impedance spectroscopic experiments.

Metabolic adaptations of Azospirillum brasilense to oxygen stress by cell-to-cell clumping and flocculation.

PubMed

Bible, Amber N; Khalsa-Moyers, Gurusahai K; Mukherjee, Tanmoy; Green, Calvin S; Mishra, Priyanka; Purcell, Alicia; Aksenova, Anastasia; Hurst, Gregory B; Alexandre, Gladys

2015-12-01

The ability of bacteria to monitor their metabolism and adjust their behavior accordingly is critical to maintain competitiveness in the environment. The motile microaerophilic bacterium Azospirillum brasilense navigates oxygen gradients by aerotaxis in order to locate low oxygen concentrations that can support metabolism. When cells are exposed to elevated levels of oxygen in their surroundings, motile A. brasilense cells implement an alternative response to aerotaxis and form transient clumps by cell-to-cell interactions. Clumping was suggested to represent a behavior protecting motile cells from transiently elevated levels of aeration. Using the proteomics of wild-type and mutant strains affected in the extent of their clumping abilities, we show that cell-to-cell clumping represents a metabolic scavenging strategy that likely prepares the cells for further metabolic stresses. Analysis of mutants affected in carbon or nitrogen metabolism confirmed this assumption. The metabolic changes experienced as clumping progresses prime cells for flocculation, a morphological and metabolic shift of cells triggered under elevated-aeration conditions and nitrogen limitation. The analysis of various mutants during clumping and flocculation characterized an ordered set of changes in cell envelope properties accompanying the metabolic changes. These data also identify clumping and early flocculation to be behaviors compatible with the expression of nitrogen fixation genes, despite the elevated-aeration conditions. Cell-to-cell clumping may thus license diazotrophy to microaerophilic A. brasilense cells under elevated oxygen conditions and prime them for long-term survival via flocculation if metabolic stress persists. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

What is a stem cell?

PubMed

Slack, Jonathan M W

2018-05-15

The historical roots of the stem cell concept are traced with respect to its usage in embryology and in hematology. The modern consensus definition of stem cells, comprising both pluripotent stem cells in culture and tissue-specific stem cells in vivo, is explained and explored. Methods for identifying stem cells are discussed with respect to cell surface markers, telomerase, label retention and transplantability, and properties of the stem cell niche are explored. The CreER method for identifying stem cells in vivo is explained, as is evidence in favor of a stochastic rather than an obligate asymmetric form of cell division. In conclusion, it is found that stem cells do not possess any unique and specific molecular markers; and stem cell behavior depends on the environment of the cell as well as the stem cell's intrinsic qualities. Furthermore, the stochastic mode of division implies that stem cell behavior is a property of a cell population not of an individual cell. In this sense, stem cells do not exist in isolation but only as a part of multicellular system. This article is categorized under: Adult Stem Cells, Tissue Renewal, and Regeneration > Tissue Stem Cells and Niches Adult Stem Cells, Tissue Renewal, and Regeneration > Methods and Principles Adult Stem Cells, Tissue Renewal, and Regeneration > Environmental Control of Stem Cells. © 2018 Wiley Periodicals, Inc.

Nrf2 regulates cellular behaviors and Notch signaling in oral squamous cell carcinoma cells.

PubMed

Fan, Hong; Paiboonrungruan, Chorlada; Zhang, Xinyan; Prigge, Justin R; Schmidt, Edward E; Sun, Zheng; Chen, Xiaoxin

2017-11-04

Oxidative stress is known to play a pivotal role in the development of oral squamous cell carcinoma (OSCC). We have demonstrated that activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway has chemopreventive effects against oxidative stress-associated OSCC. However, Nrf2 have dual roles in cancer development; while it prevents carcinogenesis of normal cells, hyperactive Nrf2 also promotes the survival of cancer cells. This study is aimed to understand the function of Nrf2 in regulating cellular behaviors of OSCC cells, and the potential mechanisms through which Nrf2 facilitates OSCC. We established the Nrf2-overexpressing and Nrf2-knockdown OSCC cell lines, and examined the function of Nrf2 in regulating cell proliferation, migration, invasion, cell cycle and colony formation. Our data showed that Nrf2 overexpression promoted cancer phenotypes in OSCC cells, whereas Nrf2 silencing inhibited these phenotypes. In addition, Nrf2 positively regulated Notch signaling pathway in OSCC cells in vitro. Consistent with this observation, Nrf2 activation in Keap1 -/- mice resulted in not only hyperproliferation of squamous epithelial cells in mouse tongue as evidenced by increased expression of PCNA, but also activation of Notch signaling in these cells as evidenced by increased expression of NICD1 and Hes1. In conclusion, Nrf2 regulates cancer behaviors and Notch signaling in OSCC cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Metabolic Adaptations of Azospirillum brasilense to Oxygen Stress by Cell-to-Cell Clumping and Flocculation

DOE PAGES

Bible, Amber N.; Khalsa-Moyers, Gurusahai K.; Mukherjee, Tanmoy; ...

2015-09-25

The ability of bacteria to monitor their metabolism and adjust their behavior accordingly is critical to maintain competitiveness in the environment. The motile microaerophilic bacteriumAzospirillum brasilensenavigates oxygen gradients by aerotaxis in order to locate low oxygen concentrations that can support metabolism. When cells are exposed to elevated levels of oxygen in their surroundings, motileA. brasilensecells implement an alternative response to aerotaxis and form transient clumps by cell-to-cell interactions. Clumping was suggested to represent a behavior protecting motile cells from transiently elevated levels of aeration. Using the proteomics of wild-type and mutant strains affected in the extent of their clumping abilities,more » we show that cell-to-cell clumping represents a metabolic scavenging strategy that likely prepares the cells for further metabolic stresses. Analysis of mutants affected in carbon or nitrogen metabolism confirmed this assumption. The metabolic changes experienced as clumping progresses prime cells for flocculation, a morphological and metabolic shift of cells triggered under elevated-aeration conditions and nitrogen limitation. The analysis of various mutants during clumping and flocculation characterized an ordered set of changes in cell envelope properties accompanying the metabolic changes. These data also identify clumping and early flocculation to be behaviors compatible with the expression of nitrogen fixation genes, despite the elevated-aeration conditions. Finally, cell-to-cell clumping may thus license diazotrophy to microaerophilicA. brasilensecells under elevated oxygen conditions and prime them for long-term survival via flocculation if metabolic stress persists.« less

Metabolic Adaptations of Azospirillum brasilense to Oxygen Stress by Cell-to-Cell Clumping and Flocculation

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

Bible, Amber N.; Khalsa-Moyers, Gurusahai K.; Mukherjee, Tanmoy

The ability of bacteria to monitor their metabolism and adjust their behavior accordingly is critical to maintain competitiveness in the environment. The motile microaerophilic bacteriumAzospirillum brasilensenavigates oxygen gradients by aerotaxis in order to locate low oxygen concentrations that can support metabolism. When cells are exposed to elevated levels of oxygen in their surroundings, motileA. brasilensecells implement an alternative response to aerotaxis and form transient clumps by cell-to-cell interactions. Clumping was suggested to represent a behavior protecting motile cells from transiently elevated levels of aeration. Using the proteomics of wild-type and mutant strains affected in the extent of their clumping abilities,more » we show that cell-to-cell clumping represents a metabolic scavenging strategy that likely prepares the cells for further metabolic stresses. Analysis of mutants affected in carbon or nitrogen metabolism confirmed this assumption. The metabolic changes experienced as clumping progresses prime cells for flocculation, a morphological and metabolic shift of cells triggered under elevated-aeration conditions and nitrogen limitation. The analysis of various mutants during clumping and flocculation characterized an ordered set of changes in cell envelope properties accompanying the metabolic changes. These data also identify clumping and early flocculation to be behaviors compatible with the expression of nitrogen fixation genes, despite the elevated-aeration conditions. Finally, cell-to-cell clumping may thus license diazotrophy to microaerophilicA. brasilensecells under elevated oxygen conditions and prime them for long-term survival via flocculation if metabolic stress persists.« less

Proinflammatory T Cell Status Associated with Early Life Adversity.

PubMed

Elwenspoek, Martha M C; Hengesch, Xenia; Leenen, Fleur A D; Schritz, Anna; Sias, Krystel; Schaan, Violetta K; Mériaux, Sophie B; Schmitz, Stephanie; Bonnemberger, Fanny; Schächinger, Hartmut; Vögele, Claus; Turner, Jonathan D; Muller, Claude P

2017-12-15

Early life adversity (ELA) has been associated with an increased risk for diseases in which the immune system plays a critical role. The ELA immune phenotype is characterized by inflammation, impaired cellular immunity, and immunosenescence. However, data on cell-specific immune effects are largely absent. Additionally, stress systems and health behaviors are altered in ELA, which may contribute to the generation of the ELA immune phenotype. The present investigation tested cell-specific immune differences in relationship to the ELA immune phenotype, altered stress parameters, and health behaviors in individuals with ELA ( n = 42) and those without a history of ELA (control, n = 73). Relative number and activation status (CD25, CD69, HLA-DR, CD11a, CD11b) of monocytes, NK cells, B cells, T cells, and their main subsets were assessed by flow cytometry. ELA was associated with significantly reduced numbers of CD69 + CD8 + T cells ( p = 0.022), increased numbers of HLA-DR + CD4 and HLA-DR + CD8 T cells ( p < 0.001), as well as increased numbers of CD25 + CD8 + T cells ( p = 0.036). ELA also showed a trend toward higher numbers of CCR4 + CXCR3 - CCR6 + CD4 T cells. Taken together, our data suggest an elevated state of immune activation in ELA, in which particularly T cells are affected. Although several aspects of the ELA immune phenotype were related to increased activation markers, neither stress nor health-risk behaviors explained the observed group differences. Thus, the state of immune activation in ELA does not seem to be secondary to alterations in the stress system or health-risk behaviors, but rather a primary effect of early life programming on immune cells. Copyright © 2017 by The American Association of Immunologists, Inc.

Use of Social Support during Communication about Sickle Cell Carrier Status

PubMed Central

Bradford, Lisa; Roedl, Sara J.; Christopher, Stephanie A.; Farrell, Michael H.

2012-01-01

Objective To examine the use of social support behaviors by primary care providers during delivery of positive newborn screening results for Sickle Cell Anemia carrier status. Methods Transcripts from 125 primary care providers who conveyed Sickle Cell Anemia carrier status to standardized parents were content analyzed using categories derived from Cutrona and Suhr’s social support taxonomy. Frequencies and cross-tabulation matrices were calculated to study providers’ social support utilization. Results Results showed most primary care providers (80%) incorporate social support behaviors into delivery of Sickle Cell Anemia carrier results and most frequently employed social network (61.6%) and informational support (38.4%) behaviors. Providers used tangible aid (8%), esteem (1.6%), and emotional support (9.6%) behaviors less frequently. Conclusion Cutrona and Suhr’s taxonomy may be a useful tool for assessing supportive communication during the delivery of Sickle Cell Anemia carrier status and could be incorporated into population scale assessments of communication quality assurance. Practice Implications Primary care providers may need training in how to adapt supportive behaviors to parents’ needs during communication of Sickle Cell Anemia carrier status. They also may benefit from specific training about how to use esteem and emotional support. PMID:22658247

Chemical Ototoxicity of the Fish Inner Ear and Lateral Line.

PubMed

Coffin, Allison B; Ramcharitar, John

2016-01-01

Hair cell-driven mechanosensory systems are crucial for successful execution of a number of behaviors in fishes, and have emerged as good models for exploring questions relevant to human hearing. This review focuses on ototoxic effects in the inner ear and lateral line system of fishes. We specifically examine studies where chemical ototoxins such as aminoglycoside antibiotics have been employed as tools to disable the lateral line. Lateral line ablation results in alterations to feeding behavior and orientation to water current in a variety of species. However, neither behavior is abolished in the presence of additional sensory cues, supporting the hypothesis that many fish behaviors are driven by multisensory integration. Within biomedical research, the larval zebrafish lateral line has become an important model system for understanding signaling mechanisms that contribute to hair cell death and for developing novel pharmacological therapies that protect hair cells from ototoxic damage. Furthermore, given that fishes robustly regenerate damaged hair cells, ototoxin studies in fishes have broadened our understanding of the molecular and genetic events in an innately regenerative system, offering potential targets for mammalian hair cell regeneration. Collectively, studies of fish mechanosensory systems have yielded insight into fish behavior and in mechanisms of hair cell death, protection, and regeneration.

Treatment Analysis in a Cancer Stem Cell Context Using a Tumor Growth Model Based on Cellular Automata.

PubMed

Monteagudo, Ángel; Santos, José

2015-01-01

Cancer can be viewed as an emergent behavior in terms of complex system theory and artificial life, Cellular Automata (CA) being the tool most used for studying and characterizing the emergent behavior. Different approaches with CA models were used to model cancer growth. The use of the abstract model of acquired cancer hallmarks permits the direct modeling at cellular level, where a cellular automaton defines the mitotic and apoptotic behavior of cells, and allows for an analysis of different dynamics of the cellular system depending on the presence of the different hallmarks. A CA model based on the presence of hallmarks in the cells, which includes a simulation of the behavior of Cancer Stem Cells (CSC) and their implications for the resultant growth behavior of the multicellular system, was employed. This modeling of cancer growth, in the avascular phase, was employed to analyze the effect of cancer treatments in a cancer stem cell context. The model clearly explains why, after treatment against non-stem cancer cells, the regrowth capability of CSCs generates a faster regrowth of tumor behavior, and also shows that a continuous low-intensity treatment does not favor CSC proliferation and differentiation, thereby allowing an unproblematic control of future tumor regrowth. The analysis performed indicates that, contrary to the current attempts at CSC control, trying to make CSC proliferation more difficult is an important point to consider, especially in the immediate period after a standard treatment for controlling non-stem cancer cell proliferation.

Strategy for signaling molecule detection by using an integrated microfluidic device coupled with mass spectrometry to study cell-to-cell communication.

PubMed

Mao, Sifeng; Zhang, Jie; Li, Haifang; Lin, Jin-Ming

2013-01-15

Cell-to-cell communication is a very important physiological behavior in life entity, and most of human behaviors are related to it. Although cell-to-cell communications are attracting much attention and financial support, rare methods have been successfully developed for in vitro cell-to-cell communication study. In this work, we developed a novel method for cell-to-cell communication study on an integrated microdevice, and signaling molecule and metabolites were online-detected by an electrospray ionization-quadrupole-time-of-flight-mass spectrometer (ESI-Q-TOF-MS) after on-chip solid-phase extraction. Moreover, we presented a "Surface Tension Plug" on a microchip to control cell-to-cell communication. The microdevice consists of three functional sections: cell coculture channel, targets pretreatment, and targets detection sections. To verify the feasibility of cell-to-cell communications on the integrated microdevice, we studied the communication between the 293 and the L-02 cells. Epinephrine and glucose were successfully detected using an ESI-Q-TOF-MS with short analysis time (<10 min). The results demonstrated that the developed microfluidic device is a potentially useful tool for high throughput cell-to-cell communication study.

Skeletal muscle satellite cells

NASA Technical Reports Server (NTRS)

Schultz, E.; McCormick, K. M.

1994-01-01

Evidence now suggests that satellite cells constitute a class of myogenic cells that differ distinctly from other embryonic myoblasts. Satellite cells arise from somites and first appear as a distinct myoblast type well before birth. Satellite cells from different muscles cannot be functionally distinguished from one another and are able to provide nuclei to all fibers without regard to phenotype. Thus, it is difficult to ascribe any significant function to establishing or stabilizing fiber type, even during regeneration. Within a muscle, satellite cells exhibit marked heterogeneity with respect to their proliferative behavior. The satellite cell population on a fiber can be partitioned into those that function as stem cells and those which are readily available for fusion. Recent studies have shown that the cells are not simply spindle shaped, but are very diverse in their morphology and have multiple branches emanating from the poles of the cells. This finding is consistent with other studies indicating that the cells have the capacity for extensive migration within, and perhaps between, muscles. Complexity of cell shape usually reflects increased cytoplasmic volume and organelles including a well developed Golgi, and is usually associated with growing postnatal muscle or muscles undergoing some form of induced adaptive change or repair. The appearance of activated satellite cells suggests some function of the cells in the adaptive process through elaboration and secretion of a product. Significant advances have been made in determining the potential secretion products that satellite cells make. The manner in which satellite cell proliferative and fusion behavior is controlled has also been studied. There seems to be little doubt that cellcell coupling is not how satellite cells and myofibers communicate. Rather satellite cell regulation is through a number of potential growth factors that arise from a number of sources. Critical to the understanding of this form of control is to determine which of the many growth factors that can alter satellite cell behavior in vitro are at work in vivo. Little work has been done to determine what controls are at work after a regeneration response has been initiated. It seems likely that, after injury, growth factors are liberated through proteolytic activity and initiate an activation process whereby cells enter into a proliferative phase. After myofibers are formed, it also seems likely that satellite cell behavior is regulated through diffusible factors arising from the fibers rather than continuous control by circulating factors.(ABSTRACT TRUNCATED AT 400 WORDS).

Theory of the high base resistivity n(+)pp(+) silicon solar cell and its application to radiation damage effects

NASA Technical Reports Server (NTRS)

Goradia, C.; Weinberg, I.

1985-01-01

Particulate radiation in space is a principal source of silicon solar cell degradation, and an investigation of cell radiation damage at higher base resistivities appears to have implication toward increasing solar cell and, therefore, useful satellite lifetimes in the space environment. However, contrary to expectations, it has been found that for cells with resistivities of 84 and 1250 ohm cm, the radiation resistance decreases as cell base resistivity increases. An analytical solar-cell computer model was developed with the objective to determine the reasons for this unexpected behavior. The present paper has the aim to describe the analytical model and its use in interpreting the behavior, under irradiation, of high-resistivity solar cells. Attention is given to boundary conditions at the space-charge region edges, cell currents, cell voltages, the generation of the theoretical I-V characteristic, experimental results, and computer calculations.

Cell Proliferation on Planar and Curved Substrates

NASA Astrophysics Data System (ADS)

Gaines, Michelle; Chang, Ya Wen; Cruz, Ricardo; Fragkopoulos, Alexandros; Garcia, Andres; Fernandez-Nieves, Alberto

Aberrant epithelial collective cell growth is one of the major challenges to be addressed in order to treat diseases such as cancer and organ fibrosis. The conditions of the extracellular microenvironment, properties of the cells' cytoskeleton, and interfacial properties of the substratum (the surface in contact with epithelial cells) have a significant influence on the migratory behavior of epithelial cells, cell proliferation and migration. This work focuses on understanding the impact the substratum curvature has on cell behavior. We focus on cell proliferation first and study MDCK cells on both planar and curved hydrogel substrates. The curved hydrogels are based on polyacrylamide and have toroidal shape, with tube radius 200 um and an aspect ratio in the rage between 2 and 9. Proliferation is measured using the Click-it EDU assay (Invitrogen), which measures cells that are synthesizing DNA. Funding Source is Childrens Healthcare of Atlanta.

Role of differential physical properties in emergent behavior of 3D cell co-cultures

NASA Astrophysics Data System (ADS)

Kolbman, Dan; Das, Moumita

2015-03-01

The biophysics of binary cell populations is of great interest in many biological processes, whether the formation of embryos or the initiation of tumors. During these processes, cells are surrounded by other cell types with different physical properties, often with important consequences. For example, recent experiments on a co-culture of breast cancer cells and healthy breast epithelial cells suggest that the mechanical mismatch between the two cell types may contribute to enhanced migration of the cancer cells. Here we explore how the differential physical properties of different cell types may influence cell-cell interaction, aggregation, and migration. To this end, we study a proof of concept model- a three-dimensional binary system of interacting, active, and deformable particles with different physical properties such as elastic stiffness, contractility, and particle-particle adhesion, using Langevin Dynamics simulations. Our results may provide insights into emergent behavior such as segregation and differential migration in cell co-cultures in three dimensions.

Collective behavior of brain tumor cells: The role of hypoxia

NASA Astrophysics Data System (ADS)

Khain, Evgeniy; Katakowski, Mark; Hopkins, Scott; Szalad, Alexandra; Zheng, Xuguang; Jiang, Feng; Chopp, Michael

2011-03-01

We consider emergent collective behavior of a multicellular biological system. Specifically, we investigate the role of hypoxia (lack of oxygen) in migration of brain tumor cells. We performed two series of cell migration experiments. In the first set of experiments, cell migration away from a tumor spheroid was investigated. The second set of experiments was performed in a typical wound-healing geometry: Cells were placed on a substrate, a scratch was made, and cell migration into the gap was investigated. Experiments show a surprising result: Cells under normal and hypoxic conditions have migrated the same distance in the “spheroid” experiment, while in the “scratch” experiment cells under normal conditions migrated much faster than under hypoxic conditions. To explain this paradox, we formulate a discrete stochastic model for cell dynamics. The theoretical model explains our experimental observations and suggests that hypoxia decreases both the motility of cells and the strength of cell-cell adhesion. The theoretical predictions were further verified in independent experiments.

Asymmetric cell division of stem cells in the lung and other systems

PubMed Central

Berika, Mohamed; Elgayyar, Marwa E.; El-Hashash, Ahmed H. K.

2014-01-01

New insights have been added to identification, behavior and cellular properties of embryonic and tissue-specific stem cells over the last few years. The modes of stem cell division, asymmetric vs. symmetric, are tightly regulated during development and regeneration. The proper choice of a stem cell to divide asymmetrically or symmetrically has great consequences for development and disease because inappropriate asymmetric division disrupts organ morphogenesis, whereas uncontrolled symmetric division induces tumorigenesis. Therefore, understanding the behavior of lung stem cells could identify innovative solutions for restoring normal morphogenesis and/or regeneration of different organs. In this concise review, we describe recent studies in our laboratory about the mode of division of lung epithelial stem cells. We also compare asymmetric cell division (ACD) in the lung stem cells with other tissues in different organisms. PMID:25364740

Agent-Based Modeling of Cancer Stem Cell Driven Solid Tumor Growth.

PubMed

Poleszczuk, Jan; Macklin, Paul; Enderling, Heiko

2016-01-01

Computational modeling of tumor growth has become an invaluable tool to simulate complex cell-cell interactions and emerging population-level dynamics. Agent-based models are commonly used to describe the behavior and interaction of individual cells in different environments. Behavioral rules can be informed and calibrated by in vitro assays, and emerging population-level dynamics may be validated with both in vitro and in vivo experiments. Here, we describe the design and implementation of a lattice-based agent-based model of cancer stem cell driven tumor growth.

Epigenetic Memory Underlies Cell-Autonomous Heterogeneous Behavior of Hematopoietic Stem Cells.

PubMed

Yu, Vionnie W C; Yusuf, Rushdia Z; Oki, Toshihiko; Wu, Juwell; Saez, Borja; Wang, Xin; Cook, Colleen; Baryawno, Ninib; Ziller, Michael J; Lee, Eunjung; Gu, Hongcang; Meissner, Alexander; Lin, Charles P; Kharchenko, Peter V; Scadden, David T

2016-11-17

Stem cells determine homeostasis and repair of many tissues and are increasingly recognized as functionally heterogeneous. To define the extent of-and molecular basis for-heterogeneity, we overlaid functional, transcriptional, and epigenetic attributes of hematopoietic stem cells (HSCs) at a clonal level using endogenous fluorescent tagging. Endogenous HSC had clone-specific functional attributes over time in vivo. The intra-clonal behaviors were highly stereotypic, conserved under the stress of transplantation, inflammation, and genotoxic injury, and associated with distinctive transcriptional, DNA methylation, and chromatin accessibility patterns. Further, HSC function corresponded to epigenetic configuration but not always to transcriptional state. Therefore, hematopoiesis under homeostatic and stress conditions represents the integrated action of highly heterogeneous clones of HSC with epigenetically scripted behaviors. This high degree of epigenetically driven cell autonomy among HSCs implies that refinement of the concepts of stem cell plasticity and of the stem cell niche is warranted. Copyright © 2016 Elsevier Inc. All rights reserved.

Autonomy and Non-autonomy of Angiogenic Cell Movements Revealed by Experiment-Driven Mathematical Modeling.

PubMed

Sugihara, Kei; Nishiyama, Koichi; Fukuhara, Shigetomo; Uemura, Akiyoshi; Arima, Satoshi; Kobayashi, Ryo; Köhn-Luque, Alvaro; Mochizuki, Naoki; Suda, Toshio; Ogawa, Hisao; Kurihara, Hiroki

2015-12-01

Angiogenesis is a multicellular phenomenon driven by morphogenetic cell movements. We recently reported morphogenetic vascular endothelial cell (EC) behaviors to be dynamic and complex. However, the principal mechanisms orchestrating individual EC movements in angiogenic morphogenesis remain largely unknown. Here we present an experiment-driven mathematical model that enables us to systematically dissect cellular mechanisms in branch elongation. We found that cell-autonomous and coordinated actions governed these multicellular behaviors, and a cell-autonomous process sufficiently illustrated essential features of the morphogenetic EC dynamics at both the single-cell and cell-population levels. Through refining our model and experimental verification, we further identified a coordinated mode of tip EC behaviors regulated via a spatial relationship between tip and follower ECs, which facilitates the forward motility of tip ECs. These findings provide insights that enhance our mechanistic understanding of not only angiogenic morphogenesis, but also other types of multicellular phenomenon. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Influence of physicochemical properties of laser-modified polystyrene on bovine serum albumin adsorption and rat C6 glioma cell behavior.

PubMed

Wang, Xuefeng; Ohlin, C André; Lu, Qinghua; Hu, Jun

2006-09-15

Biomaterial surface modification is an efficient way of improving cell-material interactions. In this study, sub-micrometer laser-induced periodic surface structures (LIPSS) were produced on polystyrene by laser irradiation. FT-IR analysis confirmed that this treatment also led to surface oxidation and anisotropic orientation of the produced carbonyl groups. As a consequence, the surface energy of the laser-treated polystyrene was 1.45 times that of the untreated polystyrene, as measured by contact-angle goniometry. Protein adsorption and rat C6 glioma cell behavior on the two substrates were investigated, showing that the changed physicochemical properties of laser-modified polystyrene surface led to an increase in the quantity of adsorbed bovine serum albumin and significantly affected the behavior of rat C6 glioma cells. In the early stages of cell spreading, cells explored their microenvironment using filopodium as the main sensor. Moreover, cells actively aligned themselves along the direction of LIPSS gradually and cell attachment and proliferation were significantly enhanced. 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006.

Femtosecond laser fabricated spike structures for selective control of cellular behavior.

PubMed

Schlie, Sabrina; Fadeeva, Elena; Koch, Jürgen; Ngezahayo, Anaclet; Chichkov, Boris N

2010-09-01

In this study we investigate the potential of femtosecond laser generated micrometer sized spike structures as functional surfaces for selective cell controlling. The spike dimensions as well as the average spike to spike distance can be easily tuned by varying the process parameters. Moreover, negative replications in soft materials such as silicone elastomer can be produced. This allows tailoring of wetting properties of the spike structures and their negative replicas representing a reduced surface contact area. Furthermore, we investigated material effects on cellular behavior. By comparing human fibroblasts and SH-SY5Y neuroblastoma cells we found that the influence of the material was cell specific. The cells not only changed their morphology, but also the cell growth was affected. Whereas, neuroblastoma cells proliferated at the same rate on the spike structures as on the control surfaces, the proliferation of fibroblasts was reduced by the spike structures. These effects can result from the cell specific adhesion patterns as shown in this work. These findings show a possibility to design defined surface microstructures, which could control cellular behavior in a cell specific manner.

Effects of subchronic inhalation of vaporized plastic cement on exploratory behavior and Purkinje cell differentiation in the rat.

PubMed

Pascual, R; Salgado, C; Viancos, L; Figueroa, H R

1996-12-06

In the present study, the effects of preweaning cement vapor inhalation on exploratory behavior and cerebellar Purkinje cell differentiation were assessed. Sprague-Dawley albino rats were daily exposed to glue vapors between postnatal d 2 and 21. At postnatal d 22, all animals were submitted to the open-field test in order to evaluate their exploratory behavior. Then they were sacrificed, their brains dissected out, and cerebella stained according to the Golgi-Cox-Sholl procedure. Purkinje cells sampled from parasagittal sections of the cerebellar vermis were drawn under camera lucida and their dendritic domain was determined. The collected data indicate that glue solvent inhalation impairs both Purkinje cell differentiation and locomotor exploratory behavior.

Elimination of Kalrn Expression in POMC Cells Reduces Anxiety-Like Behavior and Contextual Fear Learning

PubMed Central

Mandela, Prashant; Yan, Yan; LaRese, Taylor; Eipper, Betty A.; Mains, Richard E.

2014-01-01

Kalirin, a Rho GDP/GTP exchange factor for Rac1 and RhoG, is known to play an essential role in the formation and maintenance of excitatory synapses and in the secretion of neuropeptides. Mice unable to express any of the isoforms of Kalrn in cells that produce POMC at any time during development (POMC cells) exhibited reduced anxiety-like behavior and reduced acquisition of passive avoidance behavior, along with sex-specific alteration in the corticosterone response to restraint stress. Strikingly, lack of Kalrn expression in POMC cells closely mimicked the effects of global Kalrn knockout on anxiety-like behavior and passive avoidance conditioning without causing the other deficits noted in Kalrn knockout mice. Our data suggest that deficits in excitatory inputs onto POMC neurons are responsible for the behavioral phenotypes observed. PMID:25014196

Quantification of multiple gene expression in individual cells.

PubMed

Peixoto, António; Monteiro, Marta; Rocha, Benedita; Veiga-Fernandes, Henrique

2004-10-01

Quantitative gene expression analysis aims to define the gene expression patterns determining cell behavior. So far, these assessments can only be performed at the population level. Therefore, they determine the average gene expression within a population, overlooking possible cell-to-cell heterogeneity that could lead to different cell behaviors/cell fates. Understanding individual cell behavior requires multiple gene expression analyses of single cells, and may be fundamental for the understanding of all types of biological events and/or differentiation processes. We here describe a new reverse transcription-polymerase chain reaction (RT-PCR) approach allowing the simultaneous quantification of the expression of 20 genes in the same single cell. This method has broad application, in different species and any type of gene combination. RT efficiency is evaluated. Uniform and maximized amplification conditions for all genes are provided. Abundance relationships are maintained, allowing the precise quantification of the absolute number of mRNA molecules per cell, ranging from 2 to 1.28 x 10(9) for each individual gene. We evaluated the impact of this approach on functional genetic read-outs by studying an apparently homogeneous population (monoclonal T cells recovered 4 d after antigen stimulation), using either this method or conventional real-time RT-PCR. Single-cell studies revealed considerable cell-to-cell variation: All T cells did not express all individual genes. Gene coexpression patterns were very heterogeneous. mRNA copy numbers varied between different transcripts and in different cells. As a consequence, this single-cell assay introduces new and fundamental information regarding functional genomic read-outs. By comparison, we also show that conventional quantitative assays determining population averages supply insufficient information, and may even be highly misleading.

Micro-behavior and Injury of Biological Cell during Thawing Process

NASA Astrophysics Data System (ADS)

Tada, Yukio; Momose, Noboru; Jiang, Rong; Hayashi, Yujiro

This study has been conducted to pursue the relation between microscale behavior and the injury of biological cell during freezing and thawing. As a sample of biological cells, protoplasts isolated from cultured wheat cells were selectively used. As the results of microscopic observation using a cold stage whose cooling and heating velocities were controlled, the recovery of cell by water influx due to osmotic pressure difference, and the fusion of intracellular ice were clarified with heating velocity. It was found that the osmotic stress acting on the ce11 membrane causes the thawing injuries connecting with swell and rupture of cell. The survival of cells was also inspected by dye-exclusion test using Evans Blue. The results suggested rapid temperature-rising is more harmful for slowly-frozen cell.

Innate-like behavior of human invariant natural killer T cells during herpes simplex virus infection.

PubMed

Novakova, Lucie; Nevoralova, Zuzana; Novak, Jan

2012-01-01

Invariant natural killer T (iNKT) cells, CD1d restricted T cells, are involved in the immune responses against various infection agents. Here we describe their behavior during reactivation of human herpes simplex virus (HSV). iNKT cells exhibit only discrete changes, which however, reached statistically significant level due to the relatively large patient group. Higher percentage of iNKT cells express NKG2D. iNKT cells down-regulate NKG2A in a subset of patients. Finally, iNKT cells enhance their capacity to produce TNF-α. Our data suggests that iNKT cells are involved in the immune response against HSV and contribute mainly to its early, innate phase. Copyright © 2012 Elsevier Inc. All rights reserved.

Engineering nanoscale stem cell niche: direct stem cell behavior at cell-matrix interface.

PubMed

Zhang, Yan; Gordon, Andrew; Qian, Weiyi; Chen, Weiqiang

2015-09-16

Biophysical cues on the extracellular matrix (ECM) have proven to be significant regulators of stem cell behavior and evolution. Understanding the interplay of these cells and their extracellular microenvironment is critical to future tissue engineering and regenerative medicine, both of which require a means of controlled differentiation. Research suggests that nanotopography, which mimics the local, nanoscale, topographic cues within the stem cell niche, could be a way to achieve large-scale proliferation and control of stem cells in vitro. This Progress Report reviews the history and contemporary advancements of this technology, and pays special attention to nanotopographic fabrication methods and the effect of different nanoscale patterns on stem cell response. Finally, it outlines potential intracellular mechanisms behind this response. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthetic biology approaches to engineer T cells.

PubMed

Wu, Chia-Yung; Rupp, Levi J; Roybal, Kole T; Lim, Wendell A

2015-08-01

There is rapidly growing interest in learning how to engineer immune cells, such as T lymphocytes, because of the potential of these engineered cells to be used for therapeutic applications such as the recognition and killing of cancer cells. At the same time, our knowhow and capability to logically engineer cellular behavior is growing rapidly with the development of synthetic biology. Here we describe how synthetic biology approaches are being used to rationally alter the behavior of T cells to optimize them for therapeutic functions. We also describe future developments that will be important in order to construct safe and precise T cell therapeutics. Copyright © 2015 Elsevier Ltd. All rights reserved.

A three-dimensional numerical simulation of cell behavior in a flow chamber based on fluid-solid interaction.

PubMed

Bai, Long; Cui, Yuhong; Zhang, Yixia; Zhao, Na

2014-01-01

The mechanical behavior of blood cells in the vessels has a close relationship with the physical characteristics of the blood and the cells. In this paper, a numerical simulation method was proposed to understand a single-blood cell's behavior in the vessels based on fluid-solid interaction method, which was conducted under adaptive time step and fixed time step, respectively. The main programme was C++ codes, which called FLUENT and ANSYS software, and UDF and APDL acted as a messenger to connect FLUENT and ANSYS for exchanging data. The computing results show: (1) the blood cell moved towards the bottom of the flow chamber in the beginning due to the influence of gravity, then it began to jump up when reached a certain height rather than touching the bottom. It could move downwards again after jump up, the blood cell could keep this way of moving like dancing continuously in the vessels; (2) the blood cell was rolling and deforming all the time; the rotation had oscillatory changes and the deformation became conspicuously when the blood cell was dancing. This new simulation method and results can be widely used in the researches of cytology, blood, cells, etc.

Emergence of tissue mechanics from cellular processes: shaping a fly wing

NASA Astrophysics Data System (ADS)

Merkel, Matthias; Etournay, Raphael; Popovic, Marko; Nandi, Amitabha; Brandl, Holger; Salbreux, Guillaume; Eaton, Suzanne; Jülicher, Frank

Nowadays, biologistsare able to image biological tissueswith up to 10,000 cells in vivowhere the behavior of each individual cell can be followed in detail.However, how precisely large-scale tissue deformation and stresses emerge from cellular behavior remains elusive. Here, we study this question in the developing wing of the fruit fly. To this end, we first establish a geometrical framework that exactly decomposes tissue deformation into contributions by different kinds of cellular processes. These processes comprise cell shape changes, cell neighbor exchanges, cell divisions, and cell extrusions. As the key idea, we introduce a tiling of the cellular network into triangles. This approach also reveals that tissue deformation can also be created by correlated cellular motion. Based on quantifications using these concepts, we developed a novel continuum mechanical model for the fly wing. In particular, our model includes active anisotropic stresses and a delay in the response of cell rearrangements to material stresses. A different approach to study the emergence of tissue mechanics from cellular behavior are cell-based models. We characterize the properties of a cell-based model for 3D tissues that is a hybrid between single particle models and the so-called vertex models.

Genetically programmed superparamagnetic behavior of mammalian cells.

PubMed

Kim, Taeuk; Moore, David; Fussenegger, Martin

2012-12-31

Although magnetic fields and paramagnetic inorganic materials were abundant on planet earth during the entire evolution of living species the interaction of organisms with these physical forces remains a little-understood phenomenon. Interestingly, rather than being genetically encoded, organisms seem to accumulate and take advantage of inorganic nanoparticles to sense or react to magnetic fields. Using a synthetic biology-inspired approach we have genetically programmed mammalian cells to show superparamagnetic behavior. The combination of ectopic production of the human ferritin heavy chain 1 (hFTH1), engineering the cells for expression of an iron importer, the divalent metal ion transferase 1 (DMT1) and the design of an iron-loading culture medium to maximize cellular iron uptake enabled efficient iron mineralization in intracellular ferritin particles and conferred superparamagnetic behavior to the entire cell. When captured by a magnetic field the superparamagnetic cells reached attraction velocities of up to 30 μm/s and could be efficiently separated from complex cell mixtures using standard magnetic cell separation equipment. Technology that enables magnetic separation of genetically programmed superparamagnetic cells in the absence of inorganic particles could foster novel opportunities in diagnostics and cell-based therapies. Copyright © 2012 Elsevier B.V. All rights reserved.

Canine osteosarcoma cell lines from patients with differing serum alkaline phosphatase concentrations display no behavioral differences in vitro

PubMed Central

Holmes, Katie E.; Thompson, Victoria; Piskun, Caroline M.; Kohnken, Rebecca A.; Huelsmeyer, Michael K.; Fan, Timothy M.; Stein, Timothy J.

2013-01-01

Osteosarcoma is an aggressive malignancy and represents the most frequent primary bone malignancy of dogs and humans. Prognostic factors reported for osteosarcoma include tumor size, presence of metastatic disease, and serum alkaline phosphatase (ALP) concentration at the time of diagnosis. To date, there have been no studies to determine whether the behavior of osteosarcoma cells differ based on serum ALP concentration. Here we report on the generation of six canine osteosarcoma cell lines from osteosarcoma-bearing dogs with differences in serum ALP concentration. To determine whether in vitro behavior differs between primary osteosarcoma cell lines generated from patients with normal or increased serum ALP assays were performed to evaluate proliferation, migration, invasion, and chemosensitivity. There were no significant differences in cell proliferation, migration, invasion, or chemosensitivity between cell lines associated normal or increased serum ALP concentration. PMID:23489774

Innexin gap junctions in nerve cells coordinate spontaneous contractile behavior in Hydra polyps

NASA Astrophysics Data System (ADS)

Takaku, Yasuharu; Hwang, Jung Shan; Wolf, Alexander; Böttger, Angelika; Shimizu, Hiroshi; David, Charles N.; Gojobori, Takashi

2014-01-01

Nerve cells and spontaneous coordinated behavior first appeared near the base of animal evolution in the common ancestor of cnidarians and bilaterians. Experiments on the cnidarian Hydra have demonstrated that nerve cells are essential for this behavior, although nerve cells in Hydra are organized in a diffuse network and do not form ganglia. Here we show that the gap junction protein innexin-2 is expressed in a small group of nerve cells in the lower body column of Hydra and that an anti-innexin-2 antibody binds to gap junctions in the same region. Treatment of live animals with innexin-2 antibody eliminates gap junction staining and reduces spontaneous body column contractions. We conclude that a small subset of nerve cells, connected by gap junctions and capable of synchronous firing, act as a pacemaker to coordinate the contraction of the body column in the absence of ganglia.

Innexin gap junctions in nerve cells coordinate spontaneous contractile behavior in Hydra polyps

PubMed Central

Takaku, Yasuharu; Hwang, Jung Shan; Wolf, Alexander; Böttger, Angelika; Shimizu, Hiroshi; David, Charles N.; Gojobori, Takashi

2014-01-01

Nerve cells and spontaneous coordinated behavior first appeared near the base of animal evolution in the common ancestor of cnidarians and bilaterians. Experiments on the cnidarian Hydra have demonstrated that nerve cells are essential for this behavior, although nerve cells in Hydra are organized in a diffuse network and do not form ganglia. Here we show that the gap junction protein innexin-2 is expressed in a small group of nerve cells in the lower body column of Hydra and that an anti-innexin-2 antibody binds to gap junctions in the same region. Treatment of live animals with innexin-2 antibody eliminates gap junction staining and reduces spontaneous body column contractions. We conclude that a small subset of nerve cells, connected by gap junctions and capable of synchronous firing, act as a pacemaker to coordinate the contraction of the body column in the absence of ganglia. PMID:24394722

Innexin gap junctions in nerve cells coordinate spontaneous contractile behavior in Hydra polyps.

PubMed

Takaku, Yasuharu; Hwang, Jung Shan; Wolf, Alexander; Böttger, Angelika; Shimizu, Hiroshi; David, Charles N; Gojobori, Takashi

2014-01-07

Nerve cells and spontaneous coordinated behavior first appeared near the base of animal evolution in the common ancestor of cnidarians and bilaterians. Experiments on the cnidarian Hydra have demonstrated that nerve cells are essential for this behavior, although nerve cells in Hydra are organized in a diffuse network and do not form ganglia. Here we show that the gap junction protein innexin-2 is expressed in a small group of nerve cells in the lower body column of Hydra and that an anti-innexin-2 antibody binds to gap junctions in the same region. Treatment of live animals with innexin-2 antibody eliminates gap junction staining and reduces spontaneous body column contractions. We conclude that a small subset of nerve cells, connected by gap junctions and capable of synchronous firing, act as a pacemaker to coordinate the contraction of the body column in the absence of ganglia.

Coupling mechanical tension and GTPase signaling to generate cell and tissue dynamics

NASA Astrophysics Data System (ADS)

Zmurchok, Cole; Bhaskar, Dhananjay; Edelstein-Keshet, Leah

2018-07-01

Regulators of the actin cytoskeleton such Rho GTPases can modulate forces developed in cells by promoting actomyosin contraction. At the same time, through mechanosensing, tension is known to affect the activity of Rho GTPases. What happens when these effects act in concert? Using a minimal model (1 GTPase coupled to a Kelvin–Voigt element), we show that two-way feedback between signaling (‘RhoA’) and mechanical tension (stretching) leads to a spectrum of cell behaviors, including contracted or relaxed cells, and cells that oscillate between these extremes. When such ‘model cells’ are connected to one another in a row or in a 2D sheet (‘epithelium’), we observe waves of contraction/relaxation and GTPase activity sweeping through the tissue. The minimal model lends itself to full bifurcation analysis, and suggests a mechanism that explains behavior observed in the context of development and collective cell behavior.

Predictors of Cell Phone Use in Distracted Driving: Extending the Theory of Planned Behavior.

PubMed

Tian, Yan; Robinson, James D

2017-09-01

This study examines the predictors of six distracted driving behaviors, and the survey data partially support Ajzen's (1991) Theory of Planned Behavior (TPB). The data suggest that the attitude variable predicted intention to engage in all six distracted driving behaviors (reading and sending text messages, making and answering cell phone calls, reading/viewing social media, and posting on social media while driving). Extending the model to include past experience and the variable perceived safety of technology yielded an improvement in the prediction of the distraction variables. Specifically, past experience predicted all six distracted driving behaviors, and the variable perceived safety of technology predicted intentions to read/view social media and intention to post on social media while driving. The study provides evidence for the importance of incorporating expanded variables into the original TPB model to predict cell phone use behaviors while driving, and it suggests that it is essential to tailor campaign materials for each specific cell phone use behavior to reduce distracted driving.

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

PubMed

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

2016-01-01

For more than 100years, cells and tissues have been studied in vitro using glass and plastic surfaces. Over the last 10-20years, a great body of research has shown that cells are acutely sensitive to their local environment (extracellular matrix, ECM) which contains both chemical and physical cues that influence cell behavior. These observations suggest that modern cell culture systems, using tissue culture polystyrene (TCP) surfaces, may fail to reproduce authentic cell behavior in vitro, resulting in "artificial outcomes." In the current study, we use bone marrow (BM)- and adipose (AD)-derived stromal cells to prepare BM-ECM and AD-ECM, which are decellularized after synthesis by the cells, to mimic the cellular niche for each of these tissues. Each ECM was characterized for its ability to affect BM- and AD-mesenchymal stem cell (MSC) proliferation, as well as proliferation of three cancer cell lines (HeLa, MCF-7, and MDA-MB-231), modulate cell spreading, and direct differentiation relative to standard TCP surfaces. We found that both ECMs promoted the proliferation of MSCs, but that this effect was enhanced when the tissue-origin of the cells matched that of the ECM (i.e. BM-ECM promoted the proliferation of BM-MSCs over AD-MSCs, and vice versa). Moreover, BM- and AD-ECM were shown to preferentially direct MSC differentiation towards either osteogenic or adipogenic lineage, respectively, suggesting that the effects of the ECM were tissue-specific. Further, each ECM influenced cell morphology (i.e. circularity), irrespective of the origin of the MSCs, lending more support to the idea that effects were tissue specific. Interestingly, unlike MSCs, these ECMs did not promote the proliferation of the cancer cells. In an effort to further understand how these three culture substrates influence cell behavior, we evaluated the chemical (protein composition) and physical properties (architecture and mechanical) of the two ECMs. While many structural proteins (e.g. collagen and fibronectin) were found at equivalent levels in both BM- and AD-ECM, the architecture (i.e. fiber orientation; surface roughness) and physical properties (storage modulus, surface energy) of each were unique. These results, demonstrating differences in cell behavior when cultured on the three different substrates (BM- and AD-ECM and TCP) with differences in chemical and physical properties, provide evidence that the two ECMs may recapitulate specific elements of the native stem cell niche for bone marrow and adipose tissues. More broadly, it could be argued that ECMs, elaborated by cells ex vivo, serve as an ideal starting point for developing tissue-specific culture environments. In contrast to TCP, which relies on the "one size fits all" paradigm, native tissue-specific ECM may be a more rational model to approach engineering 3D tissue-specific culture systems to replicate the in vivo niche. We suggest that this approach will provide more meaningful information for basic research studies of cell behavior as well as cell-based therapeutics. Published by Elsevier B.V.

Leptin acts on neoplastic behavior and expression levels of genes related to hypoxia, angiogenesis, and invasiveness in oral squamous cell carcinoma.

PubMed

Sobrinho Santos, Eliane Macedo; Guimarães, Talita Antunes; Santos, Hércules Otacílio; Cangussu, Lilian Mendes Borborema; de Jesus, Sabrina Ferreira; Fraga, Carlos Alberto de Carvalho; Cardoso, Claudio Marcelo; Santos, Sérgio Henrique Souza; de Paula, Alfredo Maurício Batista; Gomez, Ricardo Santiago; Guimarães, André Luiz Sena; Farias, Lucyana Conceição

2017-05-01

Leptin, one of the main hormones controlling energy homeostasis, has been associated with different cancer types. In oral cancer, its effect is not well understood. We investigated, through in vitro and in vivo assays, whether leptin can affect the neoplastic behavior of oral squamous cell carcinoma. Expression of genes possibly linked to the leptin pathway was assessed in leptin-treated oral squamous cell carcinoma cells and also in tissue samples of oral squamous cell carcinoma and oral mucosa, including leptin, leptin receptor, hypoxia-inducible factor 1-alpha, E-cadherin, matrix metalloproteinase-2, matrix metalloproteinase-9, Col1A1, Ki67, and mir-210. Leptin treatment favored higher rates of cell proliferation and migration, and reduced apoptosis. Accordingly, leptin-treated oral squamous cell carcinoma cells show decreased messenger RNA caspase-3 expression, and increased levels of E-cadherin, Col1A1, matrix metalloproteinase-2, matrix metalloproteinase-9, and mir-210. In tissue samples, hypoxia-inducible factor 1-alpha messenger RNA and protein expression of leptin and leptin receptor were high in oral squamous cell carcinoma cases. Serum leptin levels were increased in first clinical stages of the disease. In animal model, oral squamous cell carcinoma-induced mice show higher leptin receptor expression, and serum leptin level was increased in dysplasia group. Our findings suggest that leptin seems to exert an effect on oral squamous cell carcinoma cells behavior and also on molecular markers related to cell proliferation, migration, and tumor angiogenesis.

Behavior-dependent activity patterns of GABAergic long-range projecting neurons in the rat hippocampus.

PubMed

Katona, Linda; Micklem, Ben; Borhegyi, Zsolt; Swiejkowski, Daniel A; Valenti, Ornella; Viney, Tim J; Kotzadimitriou, Dimitrios; Klausberger, Thomas; Somogyi, Peter

2017-04-01

Long-range glutamatergic and GABAergic projections participate in temporal coordination of neuronal activity in distributed cortical areas. In the hippocampus, GABAergic neurons project to the medial septum and retrohippocampal areas. Many GABAergic projection cells express somatostatin (SOM+) and, together with locally terminating SOM+ bistratified and O-LM cells, contribute to dendritic inhibition of pyramidal cells. We tested the hypothesis that diversity in SOM+ cells reflects temporal specialization during behavior using extracellular single cell recording and juxtacellular neurobiotin-labeling in freely moving rats. We have demonstrated that rare GABAergic projection neurons discharge rhythmically and are remarkably diverse. During sharp wave-ripples, most projection cells, including a novel SOM+ GABAergic back-projecting cell, increased their activity similar to bistratified cells, but unlike O-LM cells. During movement, most projection cells discharged along the descending slope of theta cycles, but some fired at the trough jointly with bistratified and O-LM cells. The specialization of hippocampal SOM+ projection neurons complements the action of local interneurons in differentially phasing inputs from the CA3 area to CA1 pyramidal cell dendrites during sleep and wakefulness. Our observations suggest that GABAergic projection cells mediate the behavior- and network state-dependent binding of neuronal assemblies amongst functionally-related brain regions by transmitting local rhythmic entrainment of neurons in CA1 to neuronal populations in other areas. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc.

Role of cellular adhesions in tissue dynamics spectroscopy

NASA Astrophysics Data System (ADS)

Merrill, Daniel A.; An, Ran; Turek, John; Nolte, David

2014-02-01

Cellular adhesions play a critical role in cell behavior, and modified expression of cellular adhesion compounds has been linked to various cancers. We tested the role of cellular adhesions in drug response by studying three cellular culture models: three-dimensional tumor spheroids with well-developed cellular adhesions and extracellular matrix (ECM), dense three-dimensional cell pellets with moderate numbers of adhesions, and dilute three-dimensional cell suspensions in agarose having few adhesions. Our technique for measuring the drug response for the spheroids and cell pellets was biodynamic imaging (BDI), and for the suspensions was quasi-elastic light scattering (QELS). We tested several cytoskeletal chemotherapeutic drugs (nocodazole, cytochalasin-D, paclitaxel, and colchicine) on three cancer cell lines chosen from human colorectal adenocarcinoma (HT-29), human pancreatic carcinoma (MIA PaCa-2), and rat osteosarcoma (UMR-106) to exhibit differences in adhesion strength. Comparing tumor spheroid behavior to that of cell suspensions showed shifts in the spectral motion of the cancer tissues that match predictions based on different degrees of cell-cell contacts. The HT-29 cell line, which has the strongest adhesions in the spheroid model, exhibits anomalous behavior in some cases. These results highlight the importance of using three-dimensional tissue models in drug screening with cellular adhesions being a contributory factor in phenotypic differences between the drug responses of tissue and cells.

Hippocampal cell proliferation regulation by repeated stress and antidepressants.

PubMed

Chen, Hu; Pandey, Ghanshyam N; Dwivedi, Yogesh

2006-06-26

A recent hypothesis suggests reduced hippocampal neurogenesis in depression. Here, we examined cell proliferation in the dentate gyrus and the subventricular zone of rats given repeated stress, a paradigm that prolongs learned helplessness behavior, and whether antidepressants modulate the learned helplessness-associated altered cell proliferation. Decreased cell proliferation, number of clusters, and cells/cluster were noted in the dentate gyrus, but not in the subventricular zone, of learned helplessness rats. Both fluoxetine and desipramine reversed the learned helplessness behavior and increased the cell proliferation and the number of clusters in learned helplessness rats; only fluoxetine did so significantly. Both fluoxetine and desipramine significantly increased the number of cells/cluster. Our results suggest modified hippocampal neurogenesis in prolonged depression and in the mechanism of antidepressant action.

An Off-Lattice Hybrid Discrete-Continuum Model of Tumor Growth and Invasion

PubMed Central

Jeon, Junhwan; Quaranta, Vito; Cummings, Peter T.

2010-01-01

Abstract We have developed an off-lattice hybrid discrete-continuum (OLHDC) model of tumor growth and invasion. The continuum part of the OLHDC model describes microenvironmental components such as matrix-degrading enzymes, nutrients or oxygen, and extracellular matrix (ECM) concentrations, whereas the discrete portion represents individual cell behavior such as cell cycle, cell-cell, and cell-ECM interactions and cell motility by the often-used persistent random walk, which can be depicted by the Langevin equation. Using this framework of the OLHDC model, we develop a phenomenologically realistic and bio/physically relevant model that encompasses the experimentally observed superdiffusive behavior (at short times) of mammalian cells. When systemic simulations based on the OLHDC model are performed, tumor growth and its morphology are found to be strongly affected by cell-cell adhesion and haptotaxis. There is a combination of the strength of cell-cell adhesion and haptotaxis in which fingerlike shapes, characteristic of invasive tumor, are observed. PMID:20074513

Dissecting social cell biology and tumors using Drosophila genetics.

PubMed

Pastor-Pareja, José Carlos; Xu, Tian

2013-01-01

Cancer was seen for a long time as a strictly cell-autonomous process in which oncogenes and tumor-suppressor mutations drive clonal cell expansions. Research in the past decade, however, paints a more integrative picture of communication and interplay between neighboring cells in tissues. It is increasingly clear as well that tumors, far from being homogenous lumps of cells, consist of different cell types that function together as complex tissue-level communities. The repertoire of interactive cell behaviors and the quantity of cellular players involved call for a social cell biology that investigates these interactions. Research into this social cell biology is critical for understanding development of normal and tumoral tissues. Such complex social cell biology interactions can be parsed in Drosophila. Techniques in Drosophila for analysis of gene function and clonal behavior allow us to generate tumors and dissect their complex interactive biology with cellular resolution. Here, we review recent Drosophila research aimed at understanding tissue-level biology and social cell interactions in tumors, highlighting the principles these studies reveal.

MCF-10A-NeoST: A New Cell System for Studying Cell-ECM and Cell-Cell Interactions in Breast Cancer

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

Zantek, Nicole Dodge; Walker-Daniels, Jennifer; Stewart, Jane

2001-08-22

There is a continuing need for genetically matched cell systems to model cellular behaviors that are frequently observed in aggressive breast cancers. We report here the isolation and initial characterization of a spontaneously arising variant of MCF-10A cells, NeoST, which provides a new model to study cell adhesion and signal transduction in breast cancer. NeoST cells recapitulate important biological and biochemical features of metastatic breast cancer, including anchorage-independent growth, invasiveness in threedimensional reconstituted membranes, loss of E-cadherin expression, and increased tyrosine kinase activity. A comprehensive analysis of tyrosine kinase expression revealed overexpression or functional activation of the Axl, FAK, andmore » EphA2 tyrosine kinases in transformed MCF-10A cells. MCF-10A and these new derivatives provide a genetically matched model to study defects in cell adhesion and signaling that are relevant to cellular behaviors that often typify aggressive breast cancer cells.« less

Cells on Gels: Cell Behavior at the Air-Gel Interface

NASA Astrophysics Data System (ADS)

O'Bryan, Christopher; Hormel, Tristan; Bhattacharjee, Tapomoy; Sawyer, W.; Angelini, Thomas

Numerous different types of cells are often grown at air-liquid interfaces. For example, a common way to create cell spheroids is to disperse cells in a droplet of liquid media that hangs from the lid of a culture dish - the ``hanging drop'' method. Some types of epithelial cells form monolayers at the bottom of hanging drops, instead of spheroids. Corneal epithelial cells stratify and exhibit a tissue-like phenotype when attached to liquid permeable culture surfaces positioned at the air-liquid media interface (air-lifted culture). These widely used culture methods make experimentation challenging - imaging through hanging drops and air-lifted culture dishes is prohibitive. However, similar results may be achieved by culturing cells on hydrogel surfaces at the air-gel interface. In this talk we will describe a method for culturing cells at air-gel interfaces. We seed human corneal epithelial cells (hTCEpi) onto the surfaces of hydrogel networks and jammed microgels, exposed to air. Preliminary observations of cell behavior at the air-gel interface will be presented.

Cell Growth Rate Dictates the Onset of Glass to Fluidlike Transition and Long Time Superdiffusion in an Evolving Cell Colony

NASA Astrophysics Data System (ADS)

Malmi-Kakkada, Abdul N.; Li, Xin; Samanta, Himadri S.; Sinha, Sumit; Thirumalai, D.

2018-04-01

Collective migration dominates many phenomena, from cell movement in living systems to abiotic self-propelling particles. Focusing on the early stages of tumor evolution, we enunciate the principles involved in cell dynamics and highlight their implications in understanding similar behavior in seemingly unrelated soft glassy materials and possibly chemokine-induced migration of CD 8+T cells. We performed simulations of tumor invasion using a minimal three-dimensional model, accounting for cell elasticity and adhesive cell-cell interactions, as well as cell birth and death, to establish that cell-growth-rate-dependent tumor expansion results in the emergence of distinct topological niches. Cells at the periphery move with higher velocity perpendicular to the tumor boundary, while the motion of interior cells is slower and isotropic. The mean-square displacement Δ (t ) of cells exhibits glassy behavior at times comparable to the cell cycle time, while exhibiting superdiffusive behavior, Δ (t )≈tα (α >1 ), at longer times. We derive the value of α ≈1.33 using a field theoretic approach based on stochastic quantization. In the process, we establish the universality of superdiffusion in a class of seemingly unrelated nonequilibrium systems. Superdiffusion at long times arises only if there is an imbalance between cell birth and death rates. Our findings for the collective migration, which also suggest that tumor evolution occurs in a polarized manner, are in quantitative agreement with in vitro experiments. Although set in the context of tumor invasion, the findings should also hold in describing the collective motion in growing cells and in active systems, where creation and annihilation of particles play a role.

Syndecan-2 is upregulated in colorectal cancer cells through interactions with extracellular matrix produced by stromal fibroblasts.

PubMed

Vicente, Carolina Meloni; Ricci, Ritchelli; Nader, Helena Bonciani; Toma, Leny

2013-05-25

The extracellular matrix (ECM) influences the structure, viability and functions of cells and tissues. Recent evidence indicates that tumor cells and stromal cells interact through direct cell-cell contact, the production of ECM components and the secretion of growth factors. Syndecans are a family of transmembrane heparan sulfate proteoglycans that are involved in cell adhesion, motility, proliferation and differentiation. Syndecan-2 has been found to be highly expressed in colorectal cancer cell lines and appears to be critical for cancer cell behavior. We have examined the effect of stromal fibroblast-produced ECM on the production of proteoglycans by colorectal cancer cell lines. Our results showed that in a highly metastatic colorectal cancer cell line, HCT-116, syndecan-2 expression is enhanced by fibroblast ECM, while the expression of other syndecans decreased. Of the various components of the stromal ECM, fibronectin was the most important in stimulating the increase in syndecan-2 expression. The co-localization of syndecan-2 and fibronectin suggests that these two molecules are involved in the adhesion of HCT-116 cells to the ECM. Additionally, we demonstrated an increase in the expression of integrins alpha-2 and beta-1, in addition to an increase in the expression of phospho-FAK in the presence of fibroblast ECM. Furthermore, blocking syndecan-2 with a specific antibody resulted in a decrease in cell adhesion, migration, and organization of actin filaments. Overall, these results show that interactions between cancer cells and stromal ECM proteins induce significant changes in the behavior of cancer cells. In particular, a shift from the expression of anti-tumorigenic syndecans to the tumorigenic syndecan-2 may have implications in the migratory behavior of highly metastatic tumor cells.

Cell Growth Rate Dictates the Onset of Glass to Fluid-Like Transition and Long Time Super-Diffusion in an Evolving Cell Colony

NASA Astrophysics Data System (ADS)

Malmi Kakkada, Abdul; Li, Xin; Samanta, Himadri S.; Sinha, Sumit; Thirumalai, Dave

2018-02-01

Collective migration dominates many phenomena, from cell movement in living systems to abiotic self-propelling particles. Focusing on the early stages of tumor evolution, we enunciate the principles involved in cell dynamics and highlight their implications in understanding similar behavior in seemingly unrelated soft glassy materials and possibly chemokine-induced migration of CD8$^{+}$ T cells. We performed simulations of tumor invasion using a minimal three dimensional model, accounting for cell elasticity and adhesive cell-cell interactions as well as cell birth and death to establish that cell growth rate-dependent tumor expansion results in the emergence of distinct topological niches. Cells at the periphery move with higher velocity perpendicular to the tumor boundary, while motion of interior cells is slower and isotropic. The mean square displacement, $\\Delta(t)$, of cells exhibits glassy behavior at times comparable to the cell cycle time, while exhibiting super-diffusive behavior, $\\Delta (t) \\approx t^{\\alpha}$ ($\\alpha > 1$), at longer times. We derive the value of $\\alpha \\approx 1.33$ using a field theoretic approach based on stochastic quantization. In the process we establish the universality of super-diffusion in a class of seemingly unrelated non-equilibrium systems. Super diffusion at long times arises only if there is an imbalance between cell birth and death rates. Our findings for the collective migration, which also suggests that tumor evolution occurs in a polarized manner, are in quantitative agreement with {\\it in vitro} experiments. Although set in the context of tumor invasion the findings should also hold in describing collective motion in growing cells and in active systems where creation and annihilation of particles play a role.

Regulation of behavioral plasticity by systemic temperature signaling in Caenorhabditis elegans.

PubMed

Sugi, Takuma; Nishida, Yukuo; Mori, Ikue

2011-06-26

Animals cope with environmental changes by altering behavioral strategy. Environmental information is generally received by sensory neurons in the neural circuit that generates behavior. However, although environmental temperature inevitably influences an animal's entire body, the mechanism of systemic temperature perception remains largely unknown. We show here that systemic temperature signaling induces a change in a memory-based behavior in C. elegans. During behavioral conditioning, non-neuronal cells as well as neuronal cells respond to cultivation temperature through a heat-shock transcription factor that drives newly identified gene expression dynamics. This systemic temperature signaling regulates thermosensory neurons non-cell-autonomously through the estrogen signaling pathway, producing thermotactic behavior. We provide a link between systemic environmental recognition and behavioral plasticity in the nervous system.

In Vitro Electrochemical Corrosion and Cell Viability Studies on Nickel-Free Stainless Steel Orthopedic Implants

PubMed Central

Salahinejad, Erfan; Hadianfard, Mohammad Jafar; Macdonald, Digby Donald; Sharifi-Asl, Samin; Mozafari, Masoud; Walker, Kenneth J.; Rad, Armin Tahmasbi; Madihally, Sundararajan V.; Tayebi, Lobat

2013-01-01

The corrosion and cell viability behaviors of nanostructured, nickel-free stainless steel implants were studied and compared with AISI 316L. The electrochemical studies were conducted by potentiodynamic polarization and electrochemical impedance spectroscopic measurements in a simulated body fluid. Cytocompatibility was also evaluated by the adhesion behavior of adult human stem cells on the surface of the samples. According to the results, the electrochemical behavior is affected by a compromise among the specimen's structural characteristics, comprising composition, density, and grain size. The cell viability is interpreted by considering the results of the electrochemical impedance spectroscopic experiments. PMID:23630603

Investigation of reliability attributes and accelerated stress factors on terrestrial solar cells

NASA Technical Reports Server (NTRS)

Lathrop, J. W.; Prince, J. L.

1980-01-01

Three tasks were undertaken to investigate reliability attributes of terrestrial solar cells: (1) a study of the electrical behavior of cells in the second (reverse) quadrant; (2) the accelerated stress testing of three new state-of-the-art cells; and (3) the continued bias-temperature testing of four block 2 type silicon cells at 78 C and 135 C. Electrical characteristics measured in the second quadrant were determined to be a function of the cell's thermal behavior with breakdown depending on the initiation of localized heating. This implied that high breakdown cells may be more fault tolerant when forced to operate in the second quadrant, a result contrary to conventional thinking. The accelerated stress tests used in the first (power) quadrant were bias-temperature, bias-temperature-humidity, temperature-humidity, thermal shock, and thermal cycle. The new type cells measured included an EFG cell, a polycrystalline cell, and a Czochralski cell. Significant differences in the response to the various tests were observed between cell types. A microprocessed controlled, short interval solar cell tester was designed and construction initiated on a prototype.

Bi-directional signaling: Extracellular Matrix and Integrin Regulation of Breast Tumor Progression

PubMed Central

Gehler, Scott; Ponik, Suzanne M.; Riching, Kristin M; Keely, Patricia J.

2016-01-01

Cell transformation and tumor progression involves a common set of acquired capabilities, including increased proliferation, failure of cell death, self-sufficiency in growth, angiogenesis, and tumor cell invasion and metastasis (1). The stromal environment consists of many cell types, including fibroblasts, macrophages, and endothelial cells, in addition to various extracellular matrix (ECM) proteins that function to support normal tissue maintenance, but have also been implicated in tumor progression (2). Both the chemical and mechanical properties of the ECM have been shown to influence normal and malignant cell behavior. For instance, mesenchymal stem cells differentiate into specific lineages that are dependent on matrix stiffness (3), while tumor cells undergo changes in cell behavior and gene expression in response to matrix stiffness (4). ECM remodeling is implicated in tumor progression and includes changes in both the chemical and mechanical properties of the ECM (5) that can be a result of 1.) increased deposition of stromal ECM, 2.) enhanced contraction of ECM fibrils, and 3.) altered collagen alignment and ECM stiffness. In addition, remodeling of the ECM may alter whether tumor cells employ proteolytic degradation mechanisms during invasion and metastasis. Tumor cells respond to such changes in ECM remodeling through altered intracellular signaling and cell cycle control that lead to enhanced proliferation, loss of normal tissue architecture, and local tumor cell migration and invasion into the surrounding stromal tissue (6). This review will focus on the bi-directional interplay between the mechanical properties of the ECM and changes in integrin-mediated signal transduction events in an effort to elucidate cell behaviors during tumor progression. PMID:23582036

A Finite Element Study of Micropipette Aspiration of Single Cells: Effect of Compressibility

PubMed Central

Jafari Bidhendi, Amirhossein; Korhonen, Rami K.

2012-01-01

Micropipette aspiration (MA) technique has been widely used to measure the viscoelastic properties of different cell types. Cells experience nonlinear large deformations during the aspiration procedure. Neo-Hookean viscohyperelastic (NHVH) incompressible and compressible models were used to simulate the creep behavior of cells in MA, particularly accounting for the effect of compressibility, bulk relaxation, and hardening phenomena under large strain. In order to find optimal material parameters, the models were fitted to the experimental data available for mesenchymal stem cells. Finally, through Neo-Hookean porohyperelastic (NHPH) material model for the cell, the influence of fluid flow on the aspiration length of the cell was studied. Based on the results, we suggest that the compressibility and bulk relaxation/fluid flow play a significant role in the deformation behavior of single cells and should be taken into account in the analysis of the mechanics of cells. PMID:22400045

Bioprocess Forces and Their Impact on Cell Behavior: Implications for Bone Regeneration Therapy

PubMed Central

Brindley, David; Moorthy, Kishaani; Lee, Jae-Ho; Mason, Chris; Kim, Hae-Won; Wall, Ivan

2011-01-01

Bioprocess forces such as shear stress experienced during routine cell culture are considered to be harmful to cells. However, the impact of physical forces on cell behavior is an area of growing interest within the tissue engineering community, and it is widely acknowledged that mechanical stimulation including shear stress can enhance osteogenic differentiation. This paper considers the effects of bioprocess shear stress on cell responses such as survival and proliferation in several contexts, including suspension-adapted cells used for recombinant protein and monoclonal antibody manufacture, adherent cells for therapy in suspension, and adherent cells attached to their growth substrates. The enhanced osteogenic differentiation that fluid flow shear stress is widely found to induce is discussed, along with the tissue engineering of mineralized tissue using perfusion bioreactors. Recent evidence that bioprocess forces produced during capillary transfer or pipetting of cell suspensions can enhance osteogenic responses is also discussed. PMID:21904661

Time-Dependent Migratory Behaviors in the Long-Term Studies of Fibroblast Durotaxis on a Hydrogel Substrate Fabricated with a Soft Band

PubMed Central

2015-01-01

Durotaxis, biased cell movement up a stiffness gradient on culture substrates, is one of the useful taxis behaviors for manipulating cell migration on engineered biomaterial surfaces. In this study, long-term durotaxis was investigated on gelatinous substrates containing a soft band of 20, 50, and 150 μm in width fabricated using photolithographic elasticity patterning; sharp elasticity boundaries with a gradient strength of 300 kPa/50 μm were achieved. Time-dependent migratory behaviors of 3T3 fibroblast cells were observed during a time period of 3 days. During the first day, most of the cells were strongly repelled by the soft band independent of bandwidth, exhibiting the typical durotaxis behavior. However, the repellency by the soft band diminished, and more cells crossed the soft band or exhibited other mixed migratory behaviors during the course of the observation. It was found that durotaxis strength is weakened on the substrate with the narrowest soft band and that adherent affinity-induced entrapment becomes apparent on the widest soft band with time. Factors, such as changes in surface topography, elasticity, and/or chemistry, likely contributing to the apparent diminishing durotaxis during the extended culture were examined. Immunofluorescence analysis indicated preferential collagen deposition onto the soft band, which is derived from secretion by fibroblast cells, resulting in the increasing contribution of haptotaxis toward the soft band over time. The deposited collagen did not affect surface topography or surface elasticity but did change surface chemistry, especially on the soft band. The observed time-dependent durotaxis behaviors are the result of the mixed mechanical and chemical cues. In the studies and applications of cell migratory behavior under a controlled stimulus, it is important to thoroughly examine other (hidden) compounding stimuli in order to be able to accurately interpret data and to design suitable biomaterials to manipulate cell migration. PMID:24851722

Surface Curvature Differentially Regulates Stem Cell Migration and Differentiation via Altered Attachment Morphology and Nuclear Deformation

PubMed Central

Werner, Maike; Blanquer, Sébastien B. G.; Haimi, Suvi P.; Korus, Gabriela; Dunlop, John W. C.; Duda, Georg N.; Grijpma, Dirk. W.

2016-01-01

Signals from the microenvironment around a cell are known to influence cell behavior. Material properties, such as biochemical composition and substrate stiffness, are today accepted as significant regulators of stem cell fate. The knowledge of how cell behavior is influenced by 3D geometric cues is, however, strongly limited despite its potential relevance for the understanding of tissue regenerative processes and the design of biomaterials. Here, the role of surface curvature on the migratory and differentiation behavior of human mesenchymal stem cells (hMSCs) has been investigated on 3D surfaces with well‐defined geometric features produced by stereolithography. Time lapse microscopy reveals a significant increase of cell migration speed on concave spherical compared to convex spherical structures and flat surfaces resulting from an upward‐lift of the cell body due to cytoskeletal forces. On convex surfaces, cytoskeletal forces lead to substantial nuclear deformation, increase lamin‐A levels and promote osteogenic differentiation. The findings of this study demonstrate a so far missing link between 3D surface curvature and hMSC behavior. This will not only help to better understand the role of extracellular matrix architecture in health and disease but also give new insights in how 3D geometries can be used as a cell‐instructive material parameter in the field of biomaterial‐guided tissue regeneration. PMID:28251054

Layer 2/3 pyramidal cells in the medial prefrontal cortex moderate stress induced depressive behaviors

PubMed Central

Shrestha, Prerana; Mousa, Awni; Heintz, Nathaniel

2015-01-01

Major depressive disorder (MDD) is a prevalent illness that can be precipitated by acute or chronic stress. Studies of patients with Wolfram syndrome and carriers have identified Wfs1 mutations as causative for MDD. The medial prefrontal cortex (mPFC) is known to be involved in depression and behavioral resilience, although the cell types and circuits in the mPFC that moderate depressive behaviors in response to stress have not been determined. Here, we report that deletion of Wfs1 from layer 2/3 pyramidal cells impairs the ability of the mPFC to suppress stress-induced depressive behaviors, and results in hyperactivation of the hypothalamic–pituitary–adrenal axis and altered accumulation of important growth and neurotrophic factors. Our data identify superficial layer 2/3 pyramidal cells as critical for moderation of stress in the context of depressive behaviors and suggest that dysfunction in these cells may contribute to the clinical relationship between stress and depression. DOI: http://dx.doi.org/10.7554/eLife.08752.001 PMID:26371510

The neurobiology of individuality

NASA Astrophysics Data System (ADS)

de Bivort, Benjamin

2015-03-01

Individuals often display conspicuously different patterns of behavior, even when they are very closely related genetically. These differences give rise to our sense of individuality, but what is their molecular and neurobiological basis? Individuals that are nominally genetically identical differ at various molecular and neurobiological levels: cell-to-cell variation in somatic genomes, cell-to-cell variation in expression patterns, individual-to-individual variation in neuronal morphology and physiology, and individual-to-individual variation in patterns of brain activity. It is unknown which of these levels is fundamentally causal of behavioral differences. To investigate this problem, we use the fruit fly Drosophila melanogaster, whose genetic toolkit allows the manipulation of each of these mechanistic levels, and whose rapid lifecycle and small size allows for high-throughput automation of behavioral assays. This latter point is crucial; identifying inter-individual behavioral differences requires high sample sizes both within and across individual animals. Automated behavioral characterization is at the heart of our research strategy. In every behavior examined, individual flies have individual behavioral preferences, and we have begun to identify both neural genes and circuits that control the degree of behavioral variability between individuals.

Behavioral and Physiological Changes during Benthic-Pelagic Transition in the Harmful Alga, Heterosigma akashiwo: Potential for Rapid Bloom Formation

PubMed Central

Tobin, Elizabeth D.; Grünbaum, Daniel; Patterson, Johnathan; Cattolico, Rose Ann

2013-01-01

Many species of harmful algae transition between a motile, vegetative stage in the water column and a non-motile, resting stage in the sediments. Physiological and behavioral traits expressed during benthic-pelagic transition potentially regulate the timing, location and persistence of blooms. The roles of key physiological and behavioral traits involved in resting cell emergence and bloom formation were examined in two geographically distinct strains of the harmful alga, Heterosigma akashiwo. Physiological measures of cell viability, division and population growth, and cell fatty acid content were made using flow cytometry and gas chromatography – mass spectrometry techniques as cells transitioned between the benthic resting stage and the vegetative pelagic stage. Video-based tracking was used to quantify cell-level swimming behaviors. Data show increased temperature and light triggered rapid emergence from the resting stage and initiated cell swimming. Algal strains varied in important physiological and behavioral traits, including survivorship during life-stage transitions, population growth rates and swimming velocities. Collectively, these traits function as “population growth strategies” that can influence bloom formation. Many resting cells regained the up-swimming capacity necessary to cross an environmentally relevant halocline and the ability to aggregate in near-surface waters within hours after vegetative growth supporting conditions were restored. Using a heuristic model, we illustrate how strain-specific population growth strategies can govern the timescales over which H. akashiwo blooms form. Our findings highlight the need for identification and quantification of strain-specific physiological and behavioral traits to improve mechanistic understanding of bloom formation and successful bloom prediction. PMID:24124586

Freezing behavior of adherent neuron-like cells and morphological change and viability of post-thaw cells.

PubMed

Uemura, Makoto; Ishiguro, Hiroshi

2015-04-01

Freezing of nerve cells forming a neuronal network has largely been neglected, despite the fact that the cryopreservation of nerve cells benefits the study of cells in the areas of medicine and poison screening. Freezing of nerve cells is also attractive for studying cell morphology because of the characteristic long, thread-like neurites extending from the cell body. In the present study, freezing of neuron-like cells adhering to the substrate (differentiated PC12 cells), in physiological saline, was investigated in order to understand the fundamental freezing and thawing characteristics of nerve cells with neurites. The microscopic freezing behavior of cells under different cooling rates was observed. Next, the post-thaw morphological changes in the cells, including the cytoskeleton, were investigated and post-thaw cell viability was evaluated by dye exclusion using propidium iodide. Two categories of morphological changes, beading and shortening of the neurites, were found and quantified. Also, the morphological changes of neurites due to osmotic stress from sodium chloride were studied to gain a better understanding of causation. The results showed that morphological changes and cell death were promoted with a decrease in end temperature during freezing. Copyright © 2015 Elsevier Inc. All rights reserved.

Elimination of Kalrn expression in POMC cells reduces anxiety-like behavior and contextual fear learning.

PubMed

Mandela, Prashant; Yan, Yan; LaRese, Taylor; Eipper, Betty A; Mains, Richard E

2014-07-01

Kalirin, a Rho GDP/GTP exchange factor for Rac1 and RhoG, is known to play an essential role in the formation and maintenance of excitatory synapses and in the secretion of neuropeptides. Mice unable to express any of the isoforms of Kalrn in cells that produce POMC at any time during development (POMC cells) exhibited reduced anxiety-like behavior and reduced acquisition of passive avoidance behavior, along with sex-specific alteration in the corticosterone response to restraint stress. Strikingly, lack of Kalrn expression in POMC cells closely mimicked the effects of global Kalrn knockout on anxiety-like behavior and passive avoidance conditioning without causing the other deficits noted in Kalrn knockout mice. Our data suggest that deficits in excitatory inputs onto POMC neurons are responsible for the behavioral phenotypes observed. Copyright © 2014 Elsevier Inc. All rights reserved.

Intravital imaging of multicolor-labeled tumor immune microenvironment through skin-fold window chamber

NASA Astrophysics Data System (ADS)

Qi, Shuhong; Zhang, Zhihong

2015-03-01

Tumor immune microenvironment became very important for the tumor immunotherapy. There were several kinds of immune cells in tumor stromal, and they played very different roles in tumor growth. In order to observe the behaviors of multiple immune cells in tumor microenvironment and the interaction between immune cells and tumor cells at the same time, we generated a multicolor-labeled tumor immune microenvironment model. The tumor cells and immune cells were labeled by different fluorescent proteins. By using of skin-fold window chamber implanted into mice and intravital imaging technology, we could dynamically observe the different immune cells in tumor microenvironment. After data analysis from the video, we could know the behavior of TILs, DCs and Tregs in tumor immune microenvironment; furthermore, we could know these immune cells play different roles in the tumor microenvironment.

The role of membrane microdomains in transmembrane signaling through the epithelial glycoprotein Gp140/CDCP1

PubMed Central

Alvares, Stacy M.; Dunn, Clarence A.; Brown, Tod A.; Wayner, Elizabeth E.; Carter, William G.

2008-01-01

Cell adhesion to the extracellular matrix (ECM) via integrin adhesion receptors initiates signaling cascades leading to changes in cell behavior. While integrin clustering is necessary to initiate cell attachment to the matrix, additional membrane components are necessary to mediate the transmembrane signals and the cell adhesion response that alter downstream cell behavior. Many of these signaling components reside in glycosphingolipid-rich and cholesterol-rich membrane domains such as Tetraspanin Enriched Microdomains (TEMs)/Glycosynapse 3 and Detergent-Resistant Microdomains (DRMs), also known as lipid rafts. In the following article, we will review examples of how components in these membrane microdomains modulate integrin adhesion after initial attachment to the ECM. Additionally, we will present data on a novel adhesion-responsive transmembrane glycoprotein Gp140/CUB Domain Containing Protein 1, which clusters in epithelial cell-cell contacts. Gp140 can then be phosphorylated by Src Family Kinases at tyrosine 734 in response to outside-in signals- possibly through interactions involving the extracellular CUB domains. Data presented here suggests that outside-in signals through Gp140 in cell-cell contacts assemble membrane clusters that associate with membrane microdomains to recruit and activate SFKs. Active SFKs then mediate phosphorylation of Gp140, SFK and PKCδ with Gp140 acting as a transmembrane scaffold for these kinases. We propose that the clustering of Gp140 and signaling components in membrane microdomains in cell-cell contacts contributes to changes in cell behavior. PMID:18269919

Progesterone Alleviates Neural Behavioral Deficits and Demyelination with Reduced Degeneration of Oligodendroglial Cells in Cuprizone-Induced Mice

PubMed Central

Su, Le; Liu, Yun-Lai; Cai, Qi-Yan; Zhan, Xiao-Li; Xu, Yan; Zhao, Shi-Fu; Yao, Zhong-Xiang

2013-01-01

Demyelination occurs widely in neurodegenerative diseases. Progesterone has neuroprotective effects, is known to reduce the clinical scores and the inflammatory response. Progesterone also promotes remyelination in experimental autoimmune encephalomyelitis and cuprizone-induced demyelinating brain. However, it still remains unclear whether progesterone can alleviate neural behavioral deficits and demyelination with degeneration of oligodendroglial cells in cuprizone-induced mice. In this study, mice were fed with 0.2% cuprizone to induce demyelination, and treated with progesterone to test its potential protective effect on neural behavioral deficits, demyelination and degeneration of oligodendroglial cells. Our results showed noticeable alleviation of neural behavioral deficits following progesterone treatment as assessed by changes in average body weight, and activity during the open field and Rota-rod tests when compared with the vehicle treated cuprizone group. Progesterone treatment alleviated demyelination as shown by Luxol fast blue staining, MBP immunohistochemical staining, and electron microscopy. There was an obvious decrease in TUNEL and Caspase-3-positive apoptotic cells, and an increase in the number of oligodendroglial cells staining positive for PDGFRα, Olig2, Sox10 and CC-1 antibody in the brains of cuprizone-induced mice after progesterone administration. These results indicate that progesterone can alleviate neural behavioral deficits and demyelination against oligodendroglial cell degeneration in cuprizone-induced mice. PMID:23359803

Direct Correlation between Motile Behavior and Protein Abundance in Single Cells

PubMed Central

Gillet, Sébastien; Frankel, Nicholas W.; Weibel, Douglas B.

2016-01-01

Understanding how stochastic molecular fluctuations affect cell behavior requires the quantification of both behavior and protein numbers in the same cells. Here, we combine automated microscopy with in situ hydrogel polymerization to measure single-cell protein expression after tracking swimming behavior. We characterized the distribution of non-genetic phenotypic diversity in Escherichia coli motility, which affects single-cell exploration. By expressing fluorescently tagged chemotaxis proteins (CheR and CheB) at different levels, we quantitatively mapped motile phenotype (tumble bias) to protein numbers using thousands of single-cell measurements. Our results disagreed with established models until we incorporated the role of CheB in receptor deamidation and the slow fluctuations in receptor methylation. Beyond refining models, our central finding is that changes in numbers of CheR and CheB affect the population mean tumble bias and its variance independently. Therefore, it is possible to adjust the degree of phenotypic diversity of a population by adjusting the global level of expression of CheR and CheB while keeping their ratio constant, which, as shown in previous studies, confers functional robustness to the system. Since genetic control of protein expression is heritable, our results suggest that non-genetic diversity in motile behavior is selectable, supporting earlier hypotheses that such diversity confers a selective advantage. PMID:27599206

Mesenchymal Stem Cell Fate: Applying Biomaterials for Control of Stem Cell Behavior

PubMed Central

Anderson, Hilary J.; Sahoo, Jugal Kishore; Ulijn, Rein V.; Dalby, Matthew J.

2016-01-01

The materials pipeline for biomaterials and tissue engineering applications is under continuous development. Specifically, there is great interest in the use of designed materials in the stem cell arena as materials can be used to manipulate the cells providing control of behavior. This is important as the ability to “engineer” complexity and subsequent in vitro growth of tissues and organs is a key objective for tissue engineers. This review will describe the nature of the materials strategies, both static and dynamic, and their influence specifically on mesenchymal stem cell fate. PMID:27242999

An accelerated test design for use with synchronous orbit. [on Ni-Cd cell degradation behavior

NASA Technical Reports Server (NTRS)

Mcdermott, P. P.; Vasanth, K. L.

1980-01-01

The Naval Weapons Support Center at Crane, Indiana has conducted a large scale accelerated test of 6.0 Ah Ni-Cd cells. Data from the Crane test have been used to develop an equation for the description of Ni-Cd cell behavior in geosynchronous orbit. This equation relates the anticipated time to failure for a cell in synchronous orbit to temperature and overcharge rate sustained by the cell during the light period. A test design is suggested which uses this equation for setting test parameters for future accelerated testing.

EphA2 Is a Potential Player of Malignant Cellular Behavior in Non-Metastatic Renal Cell Carcinoma Cells but Not in Metastatic Renal Cell Carcinoma Cells.

PubMed

Cho, Min Chul; Cho, Sung Yong; Yoon, Cheol Yong; Lee, Seung Bae; Kwak, Cheol; Kim, Hyeon Hoe; Jeong, Hyeon

2015-01-01

To investigate the role of EphA2 in malignant cellular behavior in renal cell carcinoma (RCC) cells and whether FAK/RhoA signaling can act as downstream effectors of EphA2 on RCC cells. Expression of EphA2 protein in non-metastatic RCC (Caki-2 and A498), metastatic RCC cells (Caki-1 and ACHN), HEK-293 cells and prostate cancer cells (PC-3 and DU-145; positive controls of EphA2 expression) was evaluated by Western blot. Changes in mRNA or protein expression of EphA2, FAK or membrane-bound RhoA following EphA2, FAK or RhoA small interfering RNA (siRNA) transfection were determined by reverse transcription polymerase chain reaction or Western blot. The effect of siRNA treatment on cellular viability, apoptosis and invasion was analyzed by cell counting kit-8, Annexin-V and modified Matrigel-Boyden assays, respectively. In all RCC cell lines, the expression of EphA2 protein was detectable at variable levels; however, in HEK-293 cells, EphA2 expression was very low. Treatment with EphA2 siRNA significantly reduced the expression of EphA2 mRNA and protein in all RCC cell lines. For non-metastatic RCC cells (Caki-2 and A498) but not metastatic RCC cells (Caki-1 and ACHN), cellular viability, invasiveness, resistance to apoptosis, expression of membrane-bound RhoA protein and FAK phosphorylation were significantly decreased in EphA2 siRNA-treated cells compared to the control. In non-metastatic RCC cells, FAK siRNA significantly attenuated the invasiveness, resistance to apoptosis, as well as expression of membrane-bound RhoA protein without changing protein expression of EphA2. RhoA siRNA significantly decreased the malignant cellular behavior and expression of membrane-bound RhoA protein without changing EphA2 protein expression or FAK phosphorylation. Our data provide the first functional evidence that the EphA2/FAK/RhoA signaling pathway plays a critical role in the malignant cellular behavior of RCC and appears to be functional particularly in the early stage of malignant progression of non-metastatic RCC.

Role of Proteome Physical Chemistry in Cell Behavior

PubMed Central

2016-01-01

We review how major cell behaviors, such as bacterial growth laws, are derived from the physical chemistry of the cell’s proteins. On one hand, cell actions depend on the individual biological functionalities of their many genes and proteins. On the other hand, the common physics among proteins can be as important as the unique biology that distinguishes them. For example, bacterial growth rates depend strongly on temperature. This dependence can be explained by the folding stabilities across a cell’s proteome. Such modeling explains how thermophilic and mesophilic organisms differ, and how oxidative damage of highly charged proteins can lead to unfolding and aggregation in aging cells. Cells have characteristic time scales. For example, E. coli can duplicate as fast as 2–3 times per hour. These time scales can be explained by protein dynamics (the rates of synthesis and degradation, folding, and diffusional transport). It rationalizes how bacterial growth is slowed down by added salt. In the same way that the behaviors of inanimate materials can be expressed in terms of the statistical distributions of atoms and molecules, some cell behaviors can be expressed in terms of distributions of protein properties, giving insights into the microscopic basis of growth laws in simple cells. PMID:27513457

Live Imaging Followed by Single Cell Tracking to Monitor Cell Biology and the Lineage Progression of Multiple Neural Populations.

PubMed

Gómez-Villafuertes, Rosa; Paniagua-Herranz, Lucía; Gascon, Sergio; de Agustín-Durán, David; Ferreras, María de la O; Gil-Redondo, Juan Carlos; Queipo, María José; Menendez-Mendez, Aida; Pérez-Sen, Ráquel; Delicado, Esmerilda G; Gualix, Javier; Costa, Marcos R; Schroeder, Timm; Miras-Portugal, María Teresa; Ortega, Felipe

2017-12-16

Understanding the mechanisms that control critical biological events of neural cell populations, such as proliferation, differentiation, or cell fate decisions, will be crucial to design therapeutic strategies for many diseases affecting the nervous system. Current methods to track cell populations rely on their final outcomes in still images and they generally fail to provide sufficient temporal resolution to identify behavioral features in single cells. Moreover, variations in cell death, behavioral heterogeneity within a cell population, dilution, spreading, or the low efficiency of the markers used to analyze cells are all important handicaps that will lead to incomplete or incorrect read-outs of the results. Conversely, performing live imaging and single cell tracking under appropriate conditions represents a powerful tool to monitor each of these events. Here, a time-lapse video-microscopy protocol, followed by post-processing, is described to track neural populations with single cell resolution, employing specific software. The methods described enable researchers to address essential questions regarding the cell biology and lineage progression of distinct neural populations.

Cell-material interactions revealed via material techniques of surface patterning.

PubMed

Yao, Xiang; Peng, Rong; Ding, Jiandong

2013-10-04

Cell-material interactions constitute a key fundamental topic in biomaterials study. Various cell cues and matrix cues as well as soluble factors regulate cell behaviors on materials. These factors are coupled with each other as usual, and thus it is very difficult to unambiguously elucidate the role of each regulator. The recently developed material techniques of surface patterning afford unique ways to reveal the underlying science. This paper reviews the pertinent material techniques to fabricate patterns of microscale and nanoscale resolutions, and corresponding cell studies. Some issues are emphasized, such as cell localization on patterned surfaces of chemical contrast, and effects of cell shape, cell size, cell-cell contact, and seeding density on differentiation of stem cells. Material cues to regulate cell adhesion, cell differentiation and other cell events are further summed up. Effects of some physical properties, such as surface topography and matrix stiffness, on cell behaviors are also discussed; nanoscaled features of substrate surfaces to regulate cell fate are summarized as well. The pertinent work sheds new insight into the cell-material interactions, and is stimulating for biomaterial design in regenerative medicine, tissue engineering, and high-throughput detection, diagnosis, and drug screening. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Relationship between nanotopographical alignment and stem cell fate with live imaging and shape analysis

NASA Astrophysics Data System (ADS)

Newman, Peter; Galenano-Niño, Jorge Luis; Graney, Pamela; Razal, Joselito M.; Minett, Andrew I.; Ribas, João; Ovalle-Robles, Raquel; Biro, Maté; Zreiqat, Hala

2016-12-01

The topography of a biomaterial regulates cellular interactions and determine stem cell fate. A complete understanding of how topographical properties affect cell behavior will allow the rational design of material surfaces that elicit specified biological functions once placed in the body. To this end, we fabricate substrates with aligned or randomly organized fibrous nanostructured topographies. Culturing adipose-derived stem cells (ASCs), we explore the dynamic relationship between the alignment of topography, cell shape and cell differentiation to osteogenic and myogenic lineages. We show aligned topographies differentiate cells towards a satellite cell muscle progenitor state - a distinct cell myogenic lineage responsible for postnatal growth and repair of muscle. We analyze cell shape between the different topographies, using fluorescent time-lapse imaging over 21 days. In contrast to previous work, this allows the direct measurement of cell shape at a given time rather than defining the morphology of the underlying topography and neglecting cell shape. We report quantitative metrics of the time-based morphological behaviors of cell shape in response to differing topographies. This analysis offers insights into the relationship between topography, cell shape and cell differentiation. Cells differentiating towards a myogenic fate on aligned topographies adopt a characteristic elongated shape as well as the alignment of cells.

Statistical Characterization of Commercial 18650-Format Lithium-Ion Cell Thermal Runaway Behavior Based on Calorimetric Testing Results

NASA Technical Reports Server (NTRS)

Walker, William; Darst, John; Finegan, Donal; Bayles, Gary; Johnson, Kenneth; Darcy, Eric; Rickman, Steven

2018-01-01

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a statistically significant number of 18650-format Li-ion cells with varying manufacturers, chemistries, and capacities. The calorimeter was designed to contain the TR energy in a format conducive to discerning the fractions of energy released through the cell casing vs. through the ejecta material. Other benefits of this calorimeter included the ability to rapidly test of large quantities of cells and the intentional minimization of secondary combustion effects. High energy (270 Wh kg-1) and moderate energy (200 Wh kg-1) 18650 cells were tested. Some of the cells had an imbedded short circuit (ISC) device installed to aid in the examination of TR mechanisms under more realistic conditions. Other variations included cells with bottom vent (BV) features and cells with thin casings (0.22 l(1/4)m). After combining the data gathered with the calorimeter, a statistical approach was used to examine the probability of certain TR behavior, and the associated energy distributions, as a function of capacity, venting features, cell casing thickness and temperature.?

Extracellular matrix elasticity and topography: material-based cues that affect cell function via conserved mechanisms

PubMed Central

Janson, Isaac A.; Putnam, Andrew J.

2014-01-01

Chemical, mechanical, and topographic extracellular matrix (ECM) cues have been extensively studied for their influence on cell behavior. These ECM cues alter cell adhesion, cell shape, and cell migration, and activate signal transduction pathways to influence gene expression, proliferation, and differentiation. ECM elasticity and topography, in particular, have emerged as material properties of intense focus based on strong evidence these physical cue can partially dictate stem cell differentiation. Cells generate forces to pull on their adhesive contacts, and these tractional forces appear to be a common element of cells’ responses to both elasticity and topography. This review focuses on recently published work that links ECM topography and mechanics and their influence on differentiation and other cell behaviors, We also highlight signaling pathways typically implicated in mechanotransduction that are (or may be) shared by cells subjected to topographic cues. Finally, we conclude with a brief discussion of the potential implications of these commonalities for cell based therapies and biomaterial design. PMID:24910444

Cadherin Switch during EMT in Neural Crest Cells Leads to Contact Inhibition of Locomotion via Repolarization of Forces.

PubMed

Scarpa, Elena; Szabó, András; Bibonne, Anne; Theveneau, Eric; Parsons, Maddy; Mayor, Roberto

2015-08-24

Contact inhibition of locomotion (CIL) is the process through which cells move away from each other after cell-cell contact, and it contributes to malignant invasion and developmental migration. Various cell types exhibit CIL, whereas others remain in contact after collision and may form stable junctions. To investigate what determines this differential behavior, we study neural crest cells, a migratory stem cell population whose invasiveness has been likened to cancer metastasis. By comparing pre-migratory and migratory neural crest cells, we show that the switch from E- to N-cadherin during EMT is essential for acquisition of CIL behavior. Loss of E-cadherin leads to repolarization of protrusions, via p120 and Rac1, resulting in a redistribution of forces from intercellular tension to cell-matrix adhesions, which break down the cadherin junction. These data provide insight into the balance of physical forces that contributes to CIL in cells in vivo. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Cadherin Switch during EMT in Neural Crest Cells Leads to Contact Inhibition of Locomotion via Repolarization of Forces

PubMed Central

Scarpa, Elena; Szabó, András; Bibonne, Anne; Theveneau, Eric; Parsons, Maddy; Mayor, Roberto

2015-01-01

Summary Contact inhibition of locomotion (CIL) is the process through which cells move away from each other after cell-cell contact, and it contributes to malignant invasion and developmental migration. Various cell types exhibit CIL, whereas others remain in contact after collision and may form stable junctions. To investigate what determines this differential behavior, we study neural crest cells, a migratory stem cell population whose invasiveness has been likened to cancer metastasis. By comparing pre-migratory and migratory neural crest cells, we show that the switch from E- to N-cadherin during EMT is essential for acquisition of CIL behavior. Loss of E-cadherin leads to repolarization of protrusions, via p120 and Rac1, resulting in a redistribution of forces from intercellular tension to cell-matrix adhesions, which break down the cadherin junction. These data provide insight into the balance of physical forces that contributes to CIL in cells in vivo. PMID:26235046

An animated landscape representation of CD4+ T-cell differentiation, variability, and plasticity: Insights into the behavior of populations versus cells

PubMed Central

Rebhahn, Jonathan A; Deng, Nan; Sharma, Gaurav; Livingstone, Alexandra M; Huang, Sui; Mosmann, Tim R

2014-01-01

Recent advances in understanding CD4+ T-cell differentiation suggest that previous models of a few distinct, stable effector phenotypes were too simplistic. Although several well-characterized phenotypes are still recognized, some states display plasticity, and intermediate phenotypes exist. As a framework for reexamining these concepts, we use Waddington's landscape paradigm, augmented with explicit consideration of stochastic variations. Our animation program “LAVA” visualizes T-cell differentiation as cells moving across a landscape of hills and valleys, leading to attractor basins representing stable or semistable differentiation states. The model illustrates several principles, including: (i) cell populations may behave more predictably than individual cells; (ii) analogous to reticulate evolution, differentiation may proceed through a network of interconnected states, rather than a single well-defined pathway; (iii) relatively minor changes in the barriers between attractor basins can change the stability or plasticity of a population; (iv) intrapopulation variability of gene expression may be an important regulator of differentiation, rather than inconsequential noise; (v) the behavior of some populations may be defined mainly by the behavior of outlier cells. While not a quantitative representation of actual differentiation, our model is intended to provoke discussion of T-cell differentiation pathways, particularly highlighting a probabilistic view of transitions between states. PMID:24945794

Probing the Behaviors of Gold Nanorods in Metastatic Breast Cancer Cells Based on UV-vis-NIR Absorption Spectroscopy

PubMed Central

Zhang, Weiqi; Ji, Yinglu; Meng, Jie; Wu, Xiaochun; Xu, Haiyan

2012-01-01

In this work, behaviors of positively-charged AuNRs in a highly metastatic tumor cell line MDA-MB-231 are examined based on UV-vis-NIR absorption spectroscopy in combination with inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and dark-field microscopic observation. It is found that characteristic surface plasmon resonance (SPR) peaks of AuNRs can be detected using spectroscopic method within living cells that have taken up AuNRs. The peak area of transverse SPR band is shown to be proportionally related to the amount of AuNRs in the cells determined with ICP-MS, which suggests a facile and real time quantification method for AuNRs in living cells. The shape of longitudinal SPR band in UV-vis-NIR spectrum reflects the aggregation state of AuNRs in the cells during the incubation period, which is proved by TEM and microscopic observations. Experimental results reveal that AuNRs are internalized by the cells rapidly; the accumulation, distribution and aggregation of AuNRs in the cells compartments are time and dose dependent. The established spectroscopic analysis method can not only monitor the behaviors of AuNRs in living cells but may also be helpful in choosing the optimum laser stimulation wavelength for anti-tumor thermotherapy. PMID:22384113

Demonstration of an electrochemical liquid cell for operando transmission electron microscopy observation of the lithiation/delithiation behavior of Si nanowire battery anodes.

PubMed

Gu, Meng; Parent, Lucas R; Mehdi, B Layla; Unocic, Raymond R; McDowell, Matthew T; Sacci, Robert L; Xu, Wu; Connell, Justin Grant; Xu, Pinghong; Abellan, Patricia; Chen, Xilin; Zhang, Yaohui; Perea, Daniel E; Evans, James E; Lauhon, Lincoln J; Zhang, Ji-Guang; Liu, Jun; Browning, Nigel D; Cui, Yi; Arslan, Ilke; Wang, Chong-Min

2013-01-01

Over the past few years, in situ transmission electron microscopy (TEM) studies of lithium ion batteries using an open-cell configuration have helped us to gain fundamental insights into the structural and chemical evolution of the electrode materials in real time. In the standard open-cell configuration, the electrolyte is either solid lithium oxide or an ionic liquid, which is point-contacted with the electrode. This cell design is inherently different from a real battery, where liquid electrolyte forms conformal contact with electrode materials. The knowledge learnt from open cells can deviate significantly from the real battery, calling for operando TEM technique with conformal liquid electrolyte contact. In this paper, we developed an operando TEM electrochemical liquid cell to meet this need, providing the configuration of a real battery and in a relevant liquid electrolyte. To demonstrate this novel technique, we studied the lithiation/delithiation behavior of single Si nanowires. Some of lithiation/delithation behaviors of Si obtained using the liquid cell are consistent with the results from the open-cell studies. However, we also discovered new insights different from the open cell configuration-the dynamics of the electrolyte and, potentially, a future quantitative characterization of the solid electrolyte interphase layer formation and structural and chemical evolution.

Ascidian notochord morphogenesis

PubMed Central

Jiang, Di; Smith, William C.

2010-01-01

The development of the notochord involves a complex set of cellular behaviors. While these morphogenic behaviors are common to all chordates, the ascidian provides a particularly attractive experimental model because of its relative simplicity. In particular, all notochord morphogenesis in ascidians takes place with only 40 cells, as opposed to the hundreds of cells in vertebrate models systems. Initial steps in ascidian notochord development convert a monolayer of epithelial-like cells in the pre-gastrula embryo to a cylindrical rod of single-cell diameter. Convergent extension is responsible for the intercalation of notochord cells and some degree of notochord elongation, while a second phase of elongation is observed as the notochord narrows medially and increases in volume. The mechanism by which the volume of the notochord increases differs between ascidian species. Some ascidian species produce extracellular pockets that will eventually coalesce to form a lumen running the length of the notochord, while others appear to make intercellular vacuoles. By either mechanism, the resulting notochord serves as a hydrostatic skeleton allowing for the locomotion of the swimming larva. Several basic cell behaviors, such as cell shape changes, cell rearrangement, establishment of cell polarity, and alteration of extracellular environment, are displayed in the process of notochord morphogenesis. Modern analysis of ascidian notochord morphogenesis promises to contribute to our understanding of these fundamental biological processes. PMID:17497687

Ascidian notochord morphogenesis.

PubMed

Jiang, Di; Smith, William C

2007-07-01

The development of the notochord involves a complex set of cellular behaviors. While these morphogenic behaviors are common to all chordates, the ascidian provides a particularly attractive experimental model because of its relative simplicity. In particular, all notochord morphogenesis in ascidians takes place with only 40 cells, as opposed to the hundreds of cells in vertebrate model systems. Initial steps in ascidian notochord development convert a monolayer of epithelial-like cells in the pregastrula embryo to a cylindrical rod of single-cell diameter. Convergent extension is responsible for the intercalation of notochord cells and some degree of notochord elongation, while a second phase of elongation is observed as the notochord narrows medially and increases in volume. The mechanism by which the volume of the notochord increases differs between ascidian species. Some ascidians produce extracellular pockets that will eventually coalesce to form a lumen running the length of the notochord; whereas others do not. By either mechanism, the resulting notochord serves as a hydrostatic skeleton allowing for the locomotion of the swimming larva. Several basic cell behaviors, such as cell shape changes, cell rearrangement, establishment of cell polarity, and alteration of extracellular environment, are displayed in the process of notochord morphogenesis. Modern analysis of ascidian notochord morphogenesis promises to contribute to our understanding of these fundamental biological processes. Copyright 2007 Wiley-Liss, Inc.

Mechanical influence of tissue culture plates and extracellular matrix on mesenchymal stem cell behavior: A topical review.

PubMed

Tatullo, Marco; Marrelli, Massimo; Falisi, Giovanni; Rastelli, Claudio; Palmieri, Francesca; Gargari, Marco; Zavan, Barbara; Paduano, Francesco; Benagiano, Vincenzo

2016-03-01

Tissue engineering applications need a continuous development of new biomaterials able to generate an ideal cell-extracellular matrix interaction. The stem cell fate is regulated by several factors, such as growth factors or transcription factors. The most recent literature has reported several publications able to demonstrate that environmental factors also contribute to the regulation of stem cell behavior, leading to the opinion that the environment plays the major role in the cell differentiation.The interaction between mesenchymal stem cells (MSCs) and extracellular environment has been widely described, and it has a crucial role in regulating the cell phenotype. In our laboratory (Tecnologica Research Institute, Crotone, Italy), we have recently studied how several physical factors influence the distribution and the morphology of MSCs isolated from dental pulp, and how they are able to regulate stem cell differentiation. Mechanical and geometrical factors are only a small part of the environmental factors able to influence stem cell behavior, however, this influence should be properly known: in fact, this assumption must be clearly considered during those studies involving MSCs; furthermore, these interactions should be considered as an important bias that involves an high number of studies on the MSCs, since in worldwide laboratories the scientists mostly use tissue culture plates for their experiments. © The Author(s) 2015.

Rotation is the primary motion of paired human epidermal keratinocytes.

PubMed

Tate, Sota; Imai, Matome; Matsushita, Natsuki; Nishimura, Emi K; Higashiyama, Shigeki; Nanba, Daisuke

2015-09-01

Collective motion of keratinocytes is involved in morphogenesis, homeostasis, and wound healing of the epidermis. Yet how the collective motion of keratinocytes emerges from the behavior of individual cells is still largely unknown. The aim of this study was to find the cellular behavior that links single and collective motion of keratinocytes. We investigated the behavior of two-cell colonies of HaCaT keratinocytes by a combination of time-lapse imaging and image processing. The two-cell colonies of HaCaT cells were formed as a contacted pair of keratinocyte clones. Image analysis and cell culture experiments revealed that the rotational speed of two-cell colonies was positively associated with their proliferative capacity. α6 integrin was required for the rotational motion of two-cell keratinocyte colonies. We also confirmed that two-cell colonies of keratinocytes predominantly exhibited the rotational, but not translational, motion, two modes of motion in a contact pair of rotating objects. The rotational motion is the primary motion of two-cell keratinocyte colonies and its speed is positively associated with their proliferative capacity. This study suggests that the assembly of rotating keratinocytes generates the collective motion of proliferative keratinocytes during morphogenesis and wound healing of the epidermis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Buckling behavior of origami unit cell facets under compressive loads

NASA Astrophysics Data System (ADS)

Kshad, Mohamed Ali Emhmed; Naguib, Hani E.

2018-03-01

Origami structures as cores for sandwich structures are designed to withstand the compressive loads and to dissipate compressive energy. The deformation of the origami panels and the unit cell facets are the primary factors behind the compressive energy dissipation in origami structures. During the loading stage, the origami structures deform through the folding and unfolding process of the unit cell facets, and also through the plastic deformation of the facets. This work presents a numerical study of the buckling behavior of different origami unit cell elements under compressive loading. The studied origami configurations were Miura and Ron-Resch-like origami structures. Finite element package was used to model the origami structures. The study investigated the buckling behavior of the unit cell facets of two types of origami structures Miura origami and Ron-Resch-Like origami structures. The simulation was conducted using ANSYS finite element software, in which the model of the unit cell represented by shell elements, and the eigenvalues buckling solver was used to predict the theoretical buckling of the unit cell elements.

Pou5f1-dependent EGF expression controls E-cad endocytosis, cell adhesion, and zebrafish epiboly movements

PubMed Central

Song, Sungmin; Eckerle, Stephanie; Onichtchouk, Daria; Marrs, James A.; Nitschke, Roland; Driever, Wolfgang

2013-01-01

Summary Initiation of motile cell behavior in embryonic development occurs during late blastula stages when gastrulation begins. At this stage, the strong adhesion of blastomeres has to be modulated to enable dynamic behavior, similar to epithelial-to-mesenchymal transitions. We show that in zebrafish MZspg embryos mutant for the stem cell transcription factor Pou5f1/Oct4, which are severely delayed in the epiboly gastrulation movement, all blastomeres are defective in E-cad endosomal trafficking and E-cad accumulates at the plasma membrane. We find that Pou5f1-dependent control of EGF expression regulates endosomal E-cad trafficking. EGFR may act via modulation of p120 activity. Loss of E-cad dynamics reduces cohesion of cells in reaggregation assays. Quantitative analysis of cell behavior indicates that dynamic E-cad endosomal trafficking is required for epiboly cell movements. We hypothesize that dynamic control of E-cad trafficking is essential to effectively generate new adhesion sites when cells move relative to each other. PMID:23484854

[The Effect of TALENs-mediated Downregulation Expression of Nanog on Malignant Behavior of Cervical Cancer HeLa Cells].

PubMed

Yu, Ai-qing; Li, Cheng-lin; Yang, Yi; Yan, Shi-rong

2016-01-01

To study the effect of downregulation expression of Nanog on malignant behavior of cervical cancer HeLa cells. Gene editing tool TALENs was employed to induce downregulation expression of Nanog, and Nanog mutation was evaluated by sequencing. RT-PCR and Western blot was used to detect the mRNA and protein expression level, respectively. Colony-formation assay, Transwell invasion assay, and chemotherapy sensibility assay was carried out to assess the capacity of colony-formation, invasion, and chemoresistance, respectively. TALENs successfully induced Nanog mutation and downregulated Nanog expression. Nanog mRNA and protein expression of Nanog-mutated monoclonal HeLa cells downregulated 3 times compared to thoses of wild-type HeLa cells (P < 0.05). Additionally, significant weakened abilities of colony-formation, invasion, and chemoresistance in monoclonal HeLa cells were observed when compared to those of wild-type HeLa cells (P < 0.05). Nanog mutation attenuates the malignant behavior of HeLa cells. Importantly, downregulation or silencing of Nanog is promising to be a novel strategy for the treatment of cervical carcinoma.

Regulation of bacteria population behaviors by AI-2 "consumer cells" and "supplier cells".

PubMed

Quan, Yufen; Meng, Fankang; Ma, Xinyu; Song, Xinhao; Liu, Xiao; Gao, Weixia; Dang, Yulei; Meng, Yao; Cao, Mingfeng; Song, Cunjiang

2017-09-19

Autoinducer-2 (AI-2) is a universal signal molecule and enables an individual bacteria to communicate with each other and ultimately control behaviors of the population. Harnessing the character of AI-2, two kinds of AI-2 "controller cells" ("consumer cells" and "supplier cells") were designed to "reprogram" the behaviors of entire population. For the consumer cells, genes associated with the uptake and processing of AI-2, which includes LsrACDB, LsrFG, LsrK, were overexpressed in varying combinations. Four consumer cell strains were constructed: Escherichia coli MG1655 pLsrACDB (NK-C1), MG1655 pLsrACDBK (NK-C2), MG1655 pLsrACDBFG (NK-C3) and MG1655 pLsrACDBFGK (NK-C4). The key enzymes responsible for production of AI-2, LuxS and Mtn, were also overexpressed, yielding strains MG1655 pLuxS (NK-SU1), and MG1655 pLuxS-Mtn (NK-SU2). All the consumer cells could decrease the environmental AI-2 concentration. NK-C2 and NK-C4 were most effective in AI-2 uptake and inhibited biofilm formation. While suppliers can increase the environmental AI-2 concentration and NK-SU2 was most effective in supplying AI-2 and facilitated biofilm formation. Further, reporter strain, MG1655 pLGFP was constructed. The expression of green fluorescent protein (GFP) in reporter cells was initiated and guided by AI-2. Mixture of consumer cells and reporter cells suggest that consumer cells can decrease the AI-2 concentration. And the supplier cells were co-cultured with reporter cells, indicating that supplier cells can provide more AI-2 compared to the control. The consumer cells and supplier cells could be used to regulate environmental AI-2 concentration and the biofilm formation. They can also modulate the AI-2 concentration when they were co-cultured with reporter cells. It can be envisioned that this system will become useful tools in synthetic biology and researching new antimicrobials.

A combined experimental atomic force microscopy-based nanoindentation and computational modeling approach to unravel the key contributors to the time-dependent mechanical behavior of single cells.

PubMed

Florea, Cristina; Tanska, Petri; Mononen, Mika E; Qu, Chengjuan; Lammi, Mikko J; Laasanen, Mikko S; Korhonen, Rami K

2017-02-01

Cellular responses to mechanical stimuli are influenced by the mechanical properties of cells and the surrounding tissue matrix. Cells exhibit viscoelastic behavior in response to an applied stress. This has been attributed to fluid flow-dependent and flow-independent mechanisms. However, the particular mechanism that controls the local time-dependent behavior of cells is unknown. Here, a combined approach of experimental AFM nanoindentation with computational modeling is proposed, taking into account complex material behavior. Three constitutive models (porohyperelastic, viscohyperelastic, poroviscohyperelastic) in tandem with optimization algorithms were employed to capture the experimental stress relaxation data of chondrocytes at 5 % strain. The poroviscohyperelastic models with and without fluid flow allowed through the cell membrane provided excellent description of the experimental time-dependent cell responses (normalized mean squared error (NMSE) of 0.003 between the model and experiments). The viscohyperelastic model without fluid could not follow the entire experimental data that well (NMSE = 0.005), while the porohyperelastic model could not capture it at all (NMSE = 0.383). We also show by parametric analysis that the fluid flow has a small, but essential effect on the loading phase and short-term cell relaxation response, while the solid viscoelasticity controls the longer-term responses. We suggest that the local time-dependent cell mechanical response is determined by the combined effects of intrinsic viscoelasticity of the cytoskeleton and fluid flow redistribution in the cells, although the contribution of fluid flow is smaller when using a nanosized probe and moderate indentation rate. The present approach provides new insights into viscoelastic responses of chondrocytes, important for further understanding cell mechanobiological mechanisms in health and disease.

STL-based Analysis of TRAIL-induced Apoptosis Challenges the Notion of Type I/Type II Cell Line Classification

PubMed Central

Bertaux, François; Maler, Oded; Batt, Gregory

2013-01-01

Extrinsic apoptosis is a programmed cell death triggered by external ligands, such as the TNF-related apoptosis inducing ligand (TRAIL). Depending on the cell line, the specific molecular mechanisms leading to cell death may significantly differ. Precise characterization of these differences is crucial for understanding and exploiting extrinsic apoptosis. Cells show distinct behaviors on several aspects of apoptosis, including (i) the relative order of caspases activation, (ii) the necessity of mitochondria outer membrane permeabilization (MOMP) for effector caspase activation, and (iii) the survival of cell lines overexpressing Bcl2. These differences are attributed to the activation of one of two pathways, leading to classification of cell lines into two groups: type I and type II. In this work we challenge this type I/type II cell line classification. We encode the three aforementioned distinguishing behaviors in a formal language, called signal temporal logic (STL), and use it to extensively test the validity of a previously-proposed model of TRAIL-induced apoptosis with respect to experimental observations made on different cell lines. After having solved a few inconsistencies using STL-guided parameter search, we show that these three criteria do not define consistent cell line classifications in type I or type II, and suggest mutants that are predicted to exhibit ambivalent behaviors. In particular, this finding sheds light on the role of a feedback loop between caspases, and reconciliates two apparently-conflicting views regarding the importance of either upstream or downstream processes for cell-type determination. More generally, our work suggests that these three distinguishing behaviors should be merely considered as type I/II features rather than cell-type defining criteria. On the methodological side, this work illustrates the biological relevance of STL-diagrams, STL population data, and STL-guided parameter search implemented in the tool Breach. Such tools are well-adapted to the ever-increasing availability of heterogeneous knowledge on complex signal transduction pathways. PMID:23675292

Sexual Behavior Increases Cell Proliferation in the Rostral Migratory Stream and Promotes the Differentiation of the New Cells into Neurons in the Accessory Olfactory Bulb of Female Rats.

PubMed

Corona, Rebeca; Retana-Márquez, Socorro; Portillo, Wendy; Paredes, Raúl G

2016-01-01

We have previously demonstrated, that 15 days after female rats pace the sexual interaction, there is an increase in the number of new cells that reach the granular cell layer (GrL) of the accessory olfactory bulb (AOB). The aim of the present study was to evaluate, if the first sexual experience in the female rat increases cell proliferation in the subventricular zone (SVZ) and the rostral migratory stream (RMS). We also tested if this behavior promotes the survival of the new cells that integrate into the main olfactory bulb (MOB) and AOB 45 days after the behavioral test. Sexually, naive female rats were injected with the DNA synthesis marker 5'-bromo-2'-deoxyuridine (BrdU) on the day of the behavioral test. They were randomly divided into the following groups: Female rats placed alone in the mating cage (1); Females exposed to amyl acetate odor [banana scent, (2)]; Females that could see, hear, and smell the male but physical contact was not possible [exposed to male, (3)]; Female rats that could pace the sexual interaction (4); and females that mated without the possibility of pacing the sexual interaction (5). Animals were sacrificed 2 days after the behavioral test (proliferation) or 45 days later (survival). Our results show that 2 days after females were exposed to banana scent or to the male, they had a higher number of cells in the SVZ. Females, that mated in pace and no-paced conditions had more new cells in the RMS. At 45 days, no significant differences were found in the number of new cells that survived in the MOB or in the AOB. However, mating increased the percentage of new cells, that differentiated into neurons in the GrL of the AOB. These new cells expressed c-Fos after a second sexual encounter just before the females were sacrificed. No significant differences in plasma levels of estradiol and progesterone were observed between groups. Our results indicate that the first sexual experience increases cell proliferation in the RMS and mating 45 days later enhances the number of new cells that differentiate into neurons in the AOB. These new neurons are activated by sexual stimulation.

Quantification of mammalian tumor cell state plasticity with digital holographic cytometry

NASA Astrophysics Data System (ADS)

Hejna, Miroslav; Jorapur, Aparna; Zhang, Yuntian; Song, Jun S.; Judson, Robert L.

2018-02-01

Individual cells within isogenic tumor populations can exhibit distinct cellular morphologies, behaviors, and molecular profiles. Cell state plasticity refers to the propensity of a cell to transition between these different morphologies and behaviors. Elevation of cell state plasticity is thought to contribute to critical stages in tumor evolution, including metastatic dissemination and acquisition of therapeutic resistance. However, methods for quantifying general plasticity in mammalian cells remain limited. Working with a HoloMonitor M4 digital holographic cytometry platform, we have established a machine learning-based pipeline for high accuracy and label-free classification of adherent cells. We use twenty-six morphological and optical density-derived features for label-free identification of cell state in heterogeneous cultures. The system is housed completely within a mammalian cell incubator, permitting the monitoring of changes in cell state over time. Here we present an application of our approach for studying cell state plasticity. Human melanoma cell lines of known metastatic potential were monitored in standard growth conditions. The rate of feature change was quantified for each individual cell in the populations. We observed that cells of higher metastatic potential exhibited more rapid fluctuation of cell state in homeostatic conditions. The approach we demonstrate will be advantageous for further investigations into the factors that influence cell state plasticity.

[Effects of stable ANO1 overexpression on biological behaviors of human laryngeal squamous cell carcinoma Hep-2 cells in vitro].

PubMed

Li, Yadong; Zhang, Jinsong; Yang, Kai; Zhang, Fujun; Chen, Rui; Chen, Dan

2014-02-01

To detect the effects of ANO1 overexpression on the biological behaviors of human laryngeal squamous cell carcinoma Hep-2 cells. A Hep-2 cell line stably overexpressing ANO1 were examined with flow cytometry, soft agar assay, wound healing assay, siRNA experiments, and chloride channel block with DIDS to observe the effect of ANO1 overexpression on the growth, migration and invasion of the cells. Flow cytometry revealed a comparable cell percentage in G0/G1 phase between ANO1-overexpressing cells and the control cells (P>0.05). The two cells showed no significant difference in soft agar assay (P>0.05), but in wound healing experiments, ANO1-overexpressing cells showed significantly accelerated migration (P<0.05), whereas siRNA-mediated silencing of ANO1 significantly inhibited the cell migration (P<0.05). Treatment with DIDS resulted in an effective block of the ANO1 chloride channel activity and obviously decreased the migration speed of Hep-2 cells. ANO1 overexpression does not significantly affect the proliferation of cancer cells, but can enhance the migration ability of head and neck squamous cell carcinoma, suggesting the value of ANO1 as a new gene therapy target for head and neck squamous cell carcinoma.

Design of a new membrane stretching device

NASA Astrophysics Data System (ADS)

Shao, Yiran

Cell stretching device has been applied into the lab use for many years to help researchers study about the behavior of cells during the stretching process. Because the cell responses to the different mechanical stimuli, especially in the case of disease, the cell stretching device is a necessary tool to study the cell behavior in a controlled environment. However existing devices have limitations, such as too big to fit the culture chamber, unable to be observed during the stretching process and too expensive to fabricate. In this thesis, a new cell stretcher is designed to resolve these limitations. Many typical cell stretching devices only work under simple conditions. For instance they can only apply the strain on the cell in uniaxial or equibiaxial directions. On the other hand the environment of cells' survival is varying. Many new cell stretchers have been developed, which have the same property that cells can be stretched via the radical deformation of the elastomeric membrane. The aim of this new design is to create a cell stretching device that fits in general lab conditions. This device is designed to fit on a microscope to observe, as well as in the incubator. In addition, two small step motors are used to control the strain, adjust the frequency, and maintain the stability precisely. Problems such as the culture media leakage and the membrane breakage are solved by the usage of multiple materials for both the cell stretcher and the membrane. Based on the experimental results, this device can satisfy the requirements of target users with a reduced manufacturing cost. In the future, an auto-focus tracking function will be developed to allow real time observation of the cells' behavior.

Systemic treatment of focal brain injury in the rat by human umbilical cord blood cells being at different level of neural commitment.

PubMed

Gornicka-Pawlak, El Bieta; Janowski, Miroslaw; Habich, Aleksandra; Jablonska, Anna; Drela, Katarzyna; Kozlowska, Hanna; Lukomska, Barbara; Sypecka, Joanna; Domanska-Janik, Krystyna

2011-01-01

The aim of the study was to evaluate therapeutic effectiveness of intra-arterial infusion of human umbilical cord blood (HUCB) derived cells at different stages of their neural conversion. Freshly isolated mononuclear cells (D-0), neurally directed progenitors (D-3) and neural-like stem cells derived from umbilical cord blood (NSC) were compared. Focal brain damage was induced in rats by stereotactic injection of ouabain into dorsolateral striatum Three days later 10(7) of different subsets of HUCB cells were infused into the right internal carotid artery. Following surgery rats were housed in enriched environment for 30 days. Behavioral assessment consisted of tests for sensorimotor deficits (walking beam, rotarod, vibrissae elicited forelimb placing, apomorphine induced rotations), cognitive impairments (habit learning and object recognition) and exploratory behavior (open field). Thirty days after surgery the lesion volume was measured and the presence of donor cells was detected in the brain at mRNA level. At the same time immunohistochemical analysis of brain tissue was performed to estimate the local tissue response of ouabain injured rats and its modulation after HUCB cells systemic treatment. Functional effects of different subsets of cord blood cells shared substantial diversity in various behavioral tests. An additional analysis showed that D-0 HUCB cells were the most effective in functional restoration and reduction of brain lesion volume. None of transplanted cord blood derived cell fractions were detected in rat's brains at 30(th) day after treatment. This may suggest that the mechanism(s) underlying positive effects of HUCB derived cell may concern the other than direct neural cell supplementation. In addition increased immunoreactivity of markers indicating local cells proliferation and migration suggests stimulation of endogenous reparative processes by HUCB D-0 cell interarterial infusion.

Inhibition of cell migration by focal adhesion kinase: Time-dependent difference in integrin-induced signaling between endothelial and hepatoblastoma cells.

PubMed

Yu, Hongchi; Gao, Min; Ma, Yunlong; Wang, Lijuan; Shen, Yang; Liu, Xiaoheng

2018-05-01

angiogenesis plays an important role in the development and progression of tumors, and it involves a series of signaling pathways contributing to the migration of endothelial cells for vascularization and to the invasion of cancer cells for secondary tumor formation. Among these pathways, the focal adhesion kinase (FAK) signaling cascade has been implicated in a variety of human cancers in connection with cell adhesion and migration events leading to tumor angiogenesis, metastasis and invasion. Therefore, the inhibition of FAK in endothelial and/or cancer cells is a potential target for anti‑angiogenic therapy. In the present study, a small‑molecule FAK inhibitor, 1,2,4,5-benzenetetramine tetrahydrochloride (Y15), was used to study the effects of FAK inhibition on the adhesion and migration behaviors of vascular endothelial cells (VECs) and human hepatoblastoma cells. Furthermore, the time-dependent differences in proteins associated with the integrin-mediated FAK/Rho GTPases signaling pathway within 2 h were examined. The results indicated that the inhibition of FAK significantly decreased the migration ability of VECs and human hepatoblastoma cells in a dose-dependent manner. Inhibition of FAK promoted cell detachment by decreasing the expression of focal adhesion components, and blocked cell motility by reducing the level of Rho GTPases. However, the expression of crucial proteins involved in integrin-induced signaling in two cell lines exhibited a time-dependent difference with increased duration of FAK inhibitor treatment, suggesting different mechanisms of FAK-mediated cell migration behavior. These results suggest that the mechanism underlying FAK-mediated adhesion and migration behavior differs among various cells, which is expected to provide evidence for future FAK therapy targeted against tumor angiogenesis.

Cell surface marker profiling of human tracheal basal cells reveals distinct subpopulations, identifies MST1/MSP as a mitogenic signal, and identifies new biomarkers for lung squamous cell carcinomas.

PubMed

Van de Laar, Emily; Clifford, Monica; Hasenoeder, Stefan; Kim, Bo Ram; Wang, Dennis; Lee, Sharon; Paterson, Josh; Vu, Nancy M; Waddell, Thomas K; Keshavjee, Shaf; Tsao, Ming-Sound; Ailles, Laurie; Moghal, Nadeem

2014-12-31

The large airways of the lungs (trachea and bronchi) are lined with a pseudostratified mucociliary epithelium, which is maintained by stem cells/progenitors within the basal cell compartment. Alterations in basal cell behavior can contribute to large airway diseases including squamous cell carcinomas (SQCCs). Basal cells have traditionally been thought of as a uniform population defined by basolateral position, cuboidal cell shape, and expression of pan-basal cell lineage markers like KRT5 and TP63. While some evidence suggests that basal cells are not all functionally equivalent, few heterogeneously expressed markers have been identified to purify and study subpopulations. In addition, few signaling pathways have been identified that regulate their cell behavior. The goals of this work were to investigate tracheal basal cell diversity and to identify new signaling pathways that regulate basal cell behavior. We used flow cytometry (FACS) to profile cell surface marker expression at a single cell level in primary human tracheal basal cell cultures that maintain stem cell/progenitor activity. FACS results were validated with tissue staining, in silico comparisons with normal basal cell and lung cancer datasets, and an in vitro proliferation assay. We identified 105 surface markers, with 47 markers identifying potential subpopulations. These subpopulations generally fell into more (~ > 13%) or less abundant (~ < 6%) groups. Microarray gene expression profiling supported the heterogeneous expression of these markers in the total population, and immunostaining of large airway tissue suggested that some of these markers are relevant in vivo. 24 markers were enriched in lung SQCCs relative to adenocarcinomas, with four markers having prognostic significance in SQCCs. We also identified 33 signaling receptors, including the MST1R/RON growth factor receptor, whose ligand MST1/MSP was mitogenic for basal cells. This work provides the largest description to date of molecular diversity among human large airway basal cells. Furthermore, these markers can be used to further study basal cell function in repair and disease, and may aid in the classification and study of SQCCs.

The level of HER2 expression is a predictor of antibody-HER2 trafficking behavior in cancer cells

PubMed Central

Ram, Sripad; Kim, Dongyoung; Ober, Raimund J; Ward, E Sally

2014-01-01

The receptor tyrosine kinase HER2 is known to play a central role in mitogenic signaling, motivating the development of targeted, HER2-specific therapies. However, despite the longstanding use of antibodies to target HER2, controversies remain concerning antibody/HER2 trafficking behavior in cancer cells. Understanding this behavior has direct relevance to the mechanism of action and effective design of such antibodies. In the current study, we analyzed the intracellular dynamics of trastuzumab, a marketed HER2-targeting antibody, in a panel of breast and prostate cancer cell lines that have a wide range of HER2 expression levels. Our results reveal distinct post-endocytic trafficking behavior of antibody-HER2 complexes in cells with different HER2 expression levels. In particular, HER2-overexpressing cells exhibit efficient HER2 recycling and limited reductions in HER2 levels upon antibody treatment, and consequently display a high level of antibody persistence on their plasma membrane. By contrast, in cells with low HER2 expression, trastuzumab treatment results in rapid antibody clearance from the plasma membrane combined with substantial decreases in HER2 levels and undetectable levels of recycling. A cell line with intermediate levels of HER2 expression exhibits both antibody recycling and clearance from the cell surface. Significantly, these analyses demonstrate that HER2 expression levels, rather than cell origin (breast or prostate), is a determinant of subcellular trafficking properties. Such studies have relevance to optimizing the design of antibodies to target HER2. PMID:25517306

The CRYPTOCHROME photoreceptor gates PDF neuropeptide signaling to set circadian network hierarchy in Drosophila.

PubMed

Zhang, Luoying; Lear, Bridget C; Seluzicki, Adam; Allada, Ravi

2009-12-15

Circadian clocks in the brain are organized as coupled oscillators that integrate seasonal cues such as light and temperature to time daily behaviors. In Drosophila, the PIGMENT DISPERSING FACTOR (PDF) neuropeptide-expressing morning (M) and non-PDF evening (E) cells are coupled cell groups important for morning and evening behavior, respectively. Depending on day length, either M cells (short days) or E cells (long days) dictate both the morning and the evening phase, a phenomenon that we term network hierarchy. To examine the role of PDF in light-dark conditions, we examined flies lacking both the PDF receptor (PDFR) and the circadian photoreceptor CRYPTOCHROME (CRY). We found that subsets of E cells exhibit molecular oscillations antiphase to those of wild-type flies, single cry mutants, or single Pdfr mutants, demonstrating a potent role for PDF in light-mediated entrainment, specifically in the absence of CRY. Moreover, we find that the evening behavioral phase is more strongly reset by PDF(+) M cells in the absence of CRY. On the basis of our findings, we propose that CRY can gate PDF signaling to determine behavioral phase and network hierarchy.

Dynamic and social behaviors of human pluripotent stem cells.

PubMed

Phadnis, Smruti M; Loewke, Nathan O; Dimov, Ivan K; Pai, Sunil; Amwake, Christine E; Solgaard, Olav; Baer, Thomas M; Chen, Bertha; Reijo Pera, Renee A

2015-09-18

Human pluripotent stem cells (hPSCs) can self-renew or differentiate to diverse cell types, thus providing a platform for basic and clinical applications. However, pluripotent stem cell populations are heterogeneous and functional properties at the single cell level are poorly documented leading to inefficiencies in differentiation and concerns regarding reproducibility and safety. Here, we use non-invasive time-lapse imaging to continuously examine hPSC maintenance and differentiation and to predict cell viability and fate. We document dynamic behaviors and social interactions that prospectively distinguish hPSC survival, self-renewal, and differentiation. Results highlight the molecular role of E-cadherin not only for cell-cell contact but also for clonal propagation of hPSCs. Results indicate that use of continuous time-lapse imaging can distinguish cellular heterogeneity with respect to pluripotency as well as a subset of karyotypic abnormalities whose dynamic properties were monitored.

Dynamic and social behaviors of human pluripotent stem cells

PubMed Central

Phadnis, Smruti M.; Loewke, Nathan O.; Dimov, Ivan K.; Pai, Sunil; Amwake, Christine E.; Solgaard, Olav; Baer, Thomas M.; Chen, Bertha; Pera, Renee A. Reijo

2015-01-01

Human pluripotent stem cells (hPSCs) can self-renew or differentiate to diverse cell types, thus providing a platform for basic and clinical applications. However, pluripotent stem cell populations are heterogeneous and functional properties at the single cell level are poorly documented leading to inefficiencies in differentiation and concerns regarding reproducibility and safety. Here, we use non-invasive time-lapse imaging to continuously examine hPSC maintenance and differentiation and to predict cell viability and fate. We document dynamic behaviors and social interactions that prospectively distinguish hPSC survival, self-renewal, and differentiation. Results highlight the molecular role of E-cadherin not only for cell-cell contact but also for clonal propagation of hPSCs. Results indicate that use of continuous time-lapse imaging can distinguish cellular heterogeneity with respect to pluripotency as well as a subset of karyotypic abnormalities whose dynamic properties were monitored. PMID:26381699

Cell-cell recognition and social networking in bacteria

PubMed Central

Troselj, Vera; Cao, Pengbo; Wall, Daniel

2018-01-01

SUMMARY The ability to recognize self and to recognize partnering cells allows microorganisms to build social networks that perform functions beyond the capabilities of the individual. In bacteria, recognition typically involves genetic determinants that provide cell surface receptors or diffusible signaling chemicals to identify proximal cells at the molecular level that can participate in cooperative processes. Social networks also rely on discriminating mechanisms to exclude competing cells from joining and exploiting their groups. In addition to their appropriate genotypes, cell-cell recognition also requires compatible phenotypes, which vary according to environmental cues or exposures as well as stochastic processes that leads to heterogeneity and potential disharmony in the population. Understanding how bacteria identify their social partners and how they synchronize their behaviors to conduct multicellular functions is an expanding field of research. Here we review recent progress in the field and contrast the various strategies used in recognition and behavioral networking. PMID:29194914

Imaging viscoelastic properties of live cells by AFM: power-law rheology on the nanoscale.

PubMed

Hecht, Fabian M; Rheinlaender, Johannes; Schierbaum, Nicolas; Goldmann, Wolfgang H; Fabry, Ben; Schäffer, Tilman E

2015-06-21

We developed force clamp force mapping (FCFM), an atomic force microscopy (AFM) technique for measuring the viscoelastic creep behavior of live cells with sub-micrometer spatial resolution. FCFM combines force-distance curves with an added force clamp phase during tip-sample contact. From the creep behavior measured during the force clamp phase, quantitative viscoelastic sample properties are extracted. We validate FCFM on soft polyacrylamide gels. We find that the creep behavior of living cells conforms to a power-law material model. By recording short (50-60 ms) force clamp measurements in rapid succession, we generate, for the first time, two-dimensional maps of power-law exponent and modulus scaling parameter. Although these maps reveal large spatial variations of both parameters across the cell surface, we obtain robust mean values from the several hundreds of measurements performed on each cell. Measurements on mouse embryonic fibroblasts show that the mean power-law exponents and the mean modulus scaling parameters differ greatly among individual cells, but both parameters are highly correlated: stiffer cells consistently show a smaller power-law exponent. This correlation allows us to distinguish between wild-type cells and cells that lack vinculin, a dominant protein of the focal adhesion complex, even though the mean values of viscoelastic properties between wildtype and knockout cells did not differ significantly. Therefore, FCFM spatially resolves viscoelastic sample properties and can uncover subtle mechanical signatures of proteins in living cells.

How do culture media influence in vitro perivascular cell behavior?

PubMed

Huber, Birgit; Volz, Ann-Cathrin; Kluger, Petra Juliane

2015-12-01

Perivascular cells are multilineage cells located around the vessel wall and important for wall stabilization. In this study, we evaluated a stem cell media and a perivascular cell-specific media for the culture of primary perivascular cells regarding their cell morphology, doubling time, stem cell properties, and expression of cell type-specific markers. When the two cell culture media were compared to each other, perivascular cells cultured in the stem cell medium had a more elongated morphology and a faster doubling rate and cells cultured in the pericyte medium had a more typical morphology, with several filopodia, and a slower doubling rate. To evaluate stem cell properties, perivascular cells, CD146(-) cells, and mesenchymal stem cells (MSCs) were differentiated into the adipogenic, osteogenic, and chondrogenic lineages. It was seen that perivascular cells, as well as CD146(-) cells and MSCs, cultured in stem cell medium showed greater differentiation than cells cultured in pericyte-specific medium. The expression of pericyte-specific markers CD146, neural/glial antigen 2 (NG2), platelet-derived growth factor receptor-β (PDGFR-β), myosin, and α-smooth muscle actin (α-SMA) could be found in both pericyte cultures, as well as to varying amounts in CD146(-) cells, MSCs, and endothelial cells. The here presented work shows that perivascular cells can adapt to their in vitro environment and cell culture conditions influence cell functionality, such as doubling rate or differentiation behavior. Pericyte-specific markers were shown to be expressed also from cells other than perivascular cells. We can further conclude that CD146(+) perivascular cells are inhomogeneous cell population probably containing stem cell subpopulations, which are located perivascular around capillaries. © 2015 International Federation for Cell Biology.

Adult neurogenesis is reduced in the dorsal hippocampus of rats displaying learned helplessness behavior.

PubMed

Ho, Y C; Wang, S

2010-11-24

Clinical and preclinical studies suggest that the hippocampus has a role in the pathophysiology of major depression. In the learned helplessness (LH) animal model of depression after inescapable shocks (ISs) animals that display LH behavior have reduced cell proliferation in the hippocampus; this effect can be reversed by antidepressant treatment. Using this model, we compared rats that displayed LH behavior and rats that did not show LH behavior (NoLH) after ISs to determine whether reduced hippocampal cell proliferation is associated with the manifestation of LH behavior or is a general response to stress. Specifically, we examined cell proliferation, neurogenesis, and synaptic function in dorsal and ventral hippocampus of LH and NoLH animals and control rats that were not shocked. The LH rats had showed reduced cell proliferation, neurogenesis, and synaptic transmission in the dorsal hippocampus, whereas no changes were seen in the ventral hippocampus. These changes were not observed in the NoLH animals. In a group of NoLH rats that received the same amount of electrical shock as the LH rats to control for the unequal shocks received in these two groups, we observed changes in Ki-67(+) cells associated with acute stress. We conclude that reduced hippocampal cell proliferation and neurogenesis are associated with the manifestation of LH behavior and that the dorsal hippocampus is the most affected area. Copyright © 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Effects of Nanotexture on Electrical Profiling of Single Tumor Cell and Detection of Cancer from Blood in Microfluidic Channels

PubMed Central

Islam, Muhymin; Motasim Bellah, Mohammad; Sajid, Adeel; Raziul Hasan, Mohammad; Kim, Young-tae; Iqbal, Samir M.

2015-01-01

Microfluidic channels have been implemented to detect cancer cells from blood using electrical measurement of each single cell from the sample. Every cell provided characteristic current profile based on its mechano-physical properties. Cancer cells not only showed higher translocation time and peak amplitude compared to blood cells, their pulse shape was also distinctively different. Prevalent microfluidic channels are plain but we created nanotexture on the channel walls using micro reactive ion etching (micro-RIE). The translocation behaviors of the metastatic renal cancer cells through plain and nanotextured PDMS microchannels showed clear differences. Nanotexture enhanced the cell-surface interactions and more than 50% tumor cells exhibited slower translocation through nanotextured channels compared to plain devices. On the other hand, most of the blood cells had very similar characteristics in both channels. Only 7.63% blood cells had slower translocation in nanotextured microchannels. The tumor cell detection efficiency from whole blood increased by 14% in nanotextured microchannels compared to plain channels. This interesting effect of nanotexture on translocation behavior of tumor cells is important for the early detection of cancer. PMID:26373820

Mast Cells Synthesize, Store, and Release Nerve Growth Factor

NASA Astrophysics Data System (ADS)

Leon, A.; Buriani, A.; dal Toso, R.; Fabris, M.; Romanello, S.; Aloe, L.; Levi-Montalcini, R.

1994-04-01

Mast cells and nerve growth factor (NGF) have both been reported to be involved in neuroimmune interactions and tissue inflammation. In many peripheral tissues, mast cells interact with the innervating fibers. Changes in the behaviors of both of these elements occur after tissue injury/inflammation. As such conditions are typically associated with rapid mast cell activation and NGF accumulation in inflammatory exudates, we hypothesized that mast cells may be capable of producing NGF. Here we report that (i) NGF mRNA is expressed in adult rat peritoneal mast cells; (ii) anti-NGF antibodies clearly stain vesicular compartments of purified mast cells and mast cells in histological sections of adult rodent mesenchymal tissues; and (iii) medium conditioned by peritoneal mast cells contains biologically active NGF. Mast cells thus represent a newly recognized source of NGF. The known actions of NGF on peripheral nerve fibers and immune cells suggest that mast cell-derived NGF may control adaptive/reactive responses of the nervous and immune systems toward noxious tissue perturbations. Conversely, alterations in normal mast cell behaviors may provoke maladaptive neuroimmune tissue responses whose consequences could have profound implications in inflammatory disease states, including those of an autoimmune nature.

Bifacial solar cell measurements under standard test conditions and the impact on cell-to-module loss analysis

NASA Astrophysics Data System (ADS)

Singh, Jai Prakash; Chai, Jing; Hsian Saw, Min; Khoo, Yong Sheng

2017-08-01

Bifacial cells are conventionally measured using gold-plated chuck, which is conductive and reflective. This measurement setup does not portray the actual operating conditions of the bifacial cells in a module. The reflective chuck causes an overestimation of the current due to the cell transmittance for the infrared light. The conductive chuck creates a shorter current flow path in the rear side of the cell and causes an over inflation of the fill factor measurement. In this study, we characterize and quantitatively analyze the difference between the bifacial cell measurements on different mounting chucks and calculate the cell-to-module (CTM) loss. To characterize the optical behavior of the bifacial cell and module, we perform external quantum efficiency, reflectance and transmittance measurements. The electrical behavior of the bifacial cell is studied using in-house developed software Griddler. Using Griddler, we calculate the difference in the fill factor of the bifacial cell due to the measurement using a conductive and non-conductive chuck, and estimate the corresponding CTM resistive losses.

KIAA0100 Modulates Cancer Cell Aggression Behavior of MDA-MB-231 through Microtubule and Heat Shock Proteins.

PubMed

Zhong, Zhenyu; Pannu, Vaishali; Rosenow, Matthew; Stark, Adam; Spetzler, David

2018-06-04

The KIAA0100 gene was identified in the human immature myeloid cell line cDNA library. Recent studies have shown that its expression is elevated in breast cancer and associated with more aggressive cancer types as well as poor outcomes. However, its cellular and molecular function is yet to be understood. Here we show that silencing KIAA0100 by siRNA in the breast cancer cell line MDA-MB-231 significantly reduced the cancer cells' aggressive behavior, including cell aggregation, reattachment, cell metastasis and invasion. Most importantly, silencing the expression of KIAA0100 particularly sensitized the quiescent cancer cells in suspension culture to anoikis. Immunoprecipitation, mass spectrometry and immunofluorescence analysis revealed that KIAA0100 may play multiple roles in the cancer cells, including stabilizing microtubule structure as a microtubule binding protein, and contributing to MDA-MB-231 cells Anoikis resistance by the interaction with stress protein HSPA1A. Our study also implies that the interaction between KIAA0100 and HSPA1A may be targeted for new drug development to specifically induce anoikis cell death in the cancer cell.

Targeting Prostate Cancer Stemlike Cells through Cell Surface Expressed GRP78

DTIC Science & Technology

2016-12-01

NOTES 14. ABSTRACT This study investigated a function for cell surface GRP78 in regulating prostate cancer stem -like cells . In year 1, we showed that...enrichment of cell surface GRP78+ cancer stem like cells in sphere culture. We also showed that the signaling axis activated by cell surface GRP78 is...but not the GRP78(-) cells , exhibited cancer stem -like cell behavior. Furthermore an GRP78 monoclonal antibody inhibited sphere forming ability of

Impact of Tumor Cell Cytoskeleton Organization on Invasiveness and Migration: A Microchannel-Based Approach

PubMed Central

Rolli, Claudio G.; Seufferlein, Thomas; Kemkemer, Ralf; Spatz, Joachim P.

2010-01-01

Cell migration is a fundamental feature of the interaction of cells with their surrounding. The cell's stiffness and ability to deform itself are two major characteristics that rule migration behavior especially in three-dimensional tissue. We simulate this situation making use of a micro-fabricated migration chip to test the active invasive behavior of pancreatic cancer cells (Panc-1) into narrow channels. At a channel width of 7 µm cell migration through the channels was significantly impeded due to size exclusion. A striking increase in cell invasiveness was observed once the cells were treated with the bioactive lipid sphingosylphosphorylcholine (SPC) that leads to a reorganization of the cell's keratin network, an enhancement of the cell's deformability, and also an increase in the cell's migration speed on flat surfaces. The migration speed of the highly deformed cells inside the channels was three times higher than of cells on flat substrates but was not affected upon SPC treatment. Cells inside the channels migrated predominantly by smooth sliding while maintaining constant cell length. In contrast, cells on adhesion mediating narrow lines moved in a stepwise way, characterized by fluctuations in cell length. Taken together, with our migration chip we demonstrate that the dimensionality of the environment strongly affects the migration phenotype and we suggest that the spatial cytoskeletal keratin organization correlates with the tumor cell's invasive potential. PMID:20090950

Final technical report for project titled Quantitative Characterization of Cell Aggregation/Adhesion as Predictor for Distribution and Transport of Microorganisms in Subsurface Environment

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

Gu, April Z.; Wan, Kai-tak

This project aims to explore and develop enabling methodology and techniques for nano-scale characterization of microbe cell surface contact mechanics, interactions and adhesion quantities that allow for identification and quantification of indicative properties related to microorganism migration and transport behavior in porous media and in subsurface environments. Microbe transport has wide impact and therefore is of great interest in various environmental applications such as in situ or enhanced subsurface bioremediation,filtration processes for water and wastewater treatments and protection of drinking water supplies. Although great progress has been made towards understanding the identities and activities of these microorganisms in the subsurface,more » to date, little is known of the mechanisms that govern the mobility and transport of microorganisms in DOE’s contaminated sites, making the outcomes of in situ natural attenuation or contaminant stability enhancement unpredictable. Conventionally, movement of microorganisms was believed to follows the rules governing solute (particle) transport. However, recent studies revealed that cell surface properties, especially those pertaining to cell attachment/adhesion and aggregation behavior, can cause the microbe behavior to deviate from non-viable particles and hence greatly influence the mobility and distribution of microorganisms in porous media.This complexity highlights the need to obtain detailed information of cell-cell and cell-surface interactions in order to improve and refine the conceptual and quantitative model development for fate and transport of microorganisms and contaminant in subsurface. Traditional cell surface characterization methods are not sufficient to fully predict the deposition rates and transport behaviors of microorganism observed. A breakthrough of methodology that would allow for quantitative and molecular-level description of intrinsic cell surface properties indicative for cell-surface interactions is essential for the field. To tackle this, we have developed a number of new Bio-nanomechanical techniques, including reflection interference contrast microscopy (RICM) and bio-AFM (Atomic Force Microscopy), for cell adhesion-detachment measurement of the long-range surface interactions, in combination with mathematical modeling, which would allow us to characterize the mechanical behavior from single cell to multi-cell aggregate, critical thresholds for large scale coaggregation and transportation of cells and aggregates in the presence of long range inter-surface forces etc. Although some technical and mathematical challenges remain, the preliminary results promise great breakthrough potential. In this study, we investigated the cellular surface characteristics of representative bio-remediating microorganisms relevant to DOE IFRC (Integrated Field-Scale Subsurface Research Challenges) sites and their transport behaviors in porous media, aiming to draw a groundbreaking correlation between the micro-scale genetic and biological origin-based cell surface properties, the consequent mechanical adhesion and aggregation behaviors, and the macro-scale microbial mobility and retention in porous media, which are unavailable in the literature. The long-term goal is to significantly improve the mechanistic and quantitative understanding of microbial mobility, sorption, and transport within reactive transport models as needed to manipulate subsurface contaminant fate and transport predictions.« less

Three-dimensional behavior of ice crystals and biological cells during freezing of cell suspensions.

PubMed

Ishiguro, H; Koike, K

1998-09-11

Behavior of ice crystals and human red blood cells during extracellular-freezing was investigated in three-dimensions using a confocal laser scanning microscope(CLSM), which noninvasively produces tomograms of biological materials. Physiological saline and physiological saline with 2.4 M glycerol were used for suspension. Various cooling rates for directional solidification were used for distinctive morphology of the ice crystals. Addition of acridine orange as a fluorescent dye into the cell suspension enabled ice crystal, cells and unfrozen solution to be distinguished by different colors. The results indicate that the microscopic structure is three-dimensional for flat, cellular, and dendritic solid-liquid interfaces and that a CLSM is very effective in studying three-dimensional structure during the freezing of cell suspensions.

Impact of mechanical stretch on the cell behaviors of bone and surrounding tissues

PubMed Central

Yu, Hye-Sun; Kim, Jung-Ju; Kim, Hae-Won; Lewis, Mark P; Wall, Ivan

2016-01-01

Mechanical loading is recognized to play an important role in regulating the behaviors of cells in bone and surrounding tissues in vivo. Many in vitro studies have been conducted to determine the effects of mechanical loading on individual cell types of the tissues. In this review, we focus specifically on the use of the Flexercell system as a tool for studying cellular responses to mechanical stretch. We assess the literature describing the impact of mechanical stretch on different cell types from bone, muscle, tendon, ligament, and cartilage, describing individual cell phenotype responses. In addition, we review evidence regarding the mechanotransduction pathways that are activated to potentiate these phenotype responses in different cell populations. PMID:26977284

Low temperature safety of lithium-thionyl chloride cells

NASA Technical Reports Server (NTRS)

Subbarao, S.; Deligiannis, F.; Shen, D. H.; Dawson, S.; Halpert, G.

1988-01-01

The use of lithium thionyl chloride cells for low-temperature applications is presently restricted because of their unsafe behavior. An attempt is made in the present investigation to identify the safe/unsafe low temperature operating conditions and to understand the low temperature cell chemistry responsible for the unsafe behavior. Cells subjected to extended reversal at low rate and -40 C were found to explode upon warm-up. Lithium was found to deposit on the carbon cathodes during reversal. Warming up to room temperature may be accelerating the lithium corrosion in the electrolyte. This may be one of the reasons for the cell thermal runaway.

Identification of Metastatic Tumor Stem Cell

DTIC Science & Technology

2010-09-01

addition to a tumor stem cell , an existence of a metastatic stem cell is predicted. Despite the critical importance of the concept, this idea has not been...isolating stem cell population from a unique set of breast tumor cell lines and by examining their metastatic behavior in an animal model. The overall...will (i) isolate stem - cell population from non-metastatic and metastatic cells of a pair of syngenic breast tumor cell lines, and test their metastatic

Matrix Elasticity of Void-Forming Hydrogels Controls Transplanted Stem Cell-Mediated Bone Formation

PubMed Central

Huebsch, Nathaniel; Lippens, Evi; Lee, Kangwon; Mehta, Manav; Koshy, Sandeep T; Darnell, Max C; Desai, Rajiv; Madl, Christopher M.; Xu, Maria; Zhao, Xuanhe; Chaudhuri, Ovijit; Verbeke, Catia; Kim, Woo Seob; Alim, Karen; Mammoto, Akiko; Ingber, Donald E.; Duda, Georg N; Mooney, David J.

2015-01-01

The effectiveness of stem-cell therapies has been hampered by cell death and limited control over fate1. These problems can be partially circumvented by using macroporous biomaterials that improve the survival of transplanted stem cells and provide molecular cues to direct cell phenotype2–4. Stem cell behavior can also be controlled in vitro by manipulating the elasticity of both porous and non-porous materials5–7, yet translation to therapeutic processes in vivo remains elusive. Here, by developing injectable, void-forming hydrogels that decouple pore formation from elasticity, we show that mesenchymal stem cell (MSC) osteogenesis in vitro, and cell deployment in vitro and in vivo, can be controlled by modifying, respectively, the hydrogel's elastic modulus or its chemistry. When the hydrogels were used to transplant MSCs, the hydrogel's elasticity regulated bone regeneration, with optimal bone formation at 60 kPa. Our findings show that biophysical cues can be harnessed to direct therapeutic stem-cell behaviors in situ. PMID:26366848

[Biological behavior of hypopharyngeal carcinoma].

PubMed

Zhou, L X

1997-01-01

Hypopharyngeal squamous cell carcinomas (HPC) has an extremely poor prognosis. Characteristics of cell lines of head and neck squamous cell carcinomas including HPC were studied by various methods, e.g., chemosensitivity test and the immunohistochemistry staining method, to determine whether this poor prognosis is due to the biological behavior of this cancer. An HPC cell line was found to be resistant to anti tumor drugs, i.e., PEP, MTX and CPM and moderately sensitive to CDDP, 5-FU and ADM. Thermoresistance to hyperthermatic treatment and weak expression of ICAM-1 on the HPC cell line were observed. DNA synthesis by the HPC cell line was induced by stimulation with a low concentration of EGF and the amount of EGFR on these HPC cells was very high. In addition, cyclinD1 overexpression was found in the HPC cell line. Based on the above findings, further analysis of hypopharyngeal carcinoma cells and the development of a new treatment modality to control tumor growth and metastatic factors influencing the poor outcome are necessary to improve the prognosis of this cancer.

Primordial oscillations in life: Direct observation of glycolytic oscillations in individual HeLa cervical cancer cells

NASA Astrophysics Data System (ADS)

Amemiya, Takashi; Shibata, Kenichi; Itoh, Yoshihiro; Itoh, Kiminori; Watanabe, Masatoshi; Yamaguchi, Tomohiko

2017-10-01

We report the first direct observation of glycolytic oscillations in HeLa cervical cancer cells, which we regard as primordial oscillations preserved in living cells. HeLa cells starved of glucose or both glucose and serum exhibited glycolytic oscillations in nicotinamide adenine dinucleotide (NADH), exhibiting asynchronous intercellular behaviors. Also found were spatially homogeneous and inhomogeneous intracellular NADH oscillations in the individual cells. Our results demonstrate that starved HeLa cells may be induced to exhibit glycolytic oscillations by either high-uptake of glucose or the enhancement of a glycolytic pathway (Crabtree effect or the Warburg effect), or both. Their asynchronous collective behaviors in the oscillations were probably due to a weak intercellular coupling. Elucidation of the relationship between the mechanism of glycolytic dynamics in cancer cells and their pathophysiological characteristics remains a challenge in future.

In vitro motility of cells from human epidermoid carcinomas. A study by phase-contrast and reflection-contrast cinematography.

PubMed

Haemmerli, G; Sträuli, P

1981-05-15

The motile behavior of six cell lines derived from human squamous carcinomas (two from the larynx, four from the tongue) was studied by cinematography under phase- and reflection-contrast illumination. The recorded cell activities consist in spreading, stationary and translocation motility, and aggregate formation. Within this common pattern, quantitative modifications ("sub-pattern") are stable properties of the individual cells lines. Such modifications are particularly evident with regard to the dynamic texture of the aggregates which ranges from loose, netlike structures to compact islands with smooth borders. Accordingly, the intensity of cell traffic within and around the aggregates varies considerably. It is discussed to what extent the in vitro motility of the carcinoma cell populations reflects their behavior in the organism and thus the significance of cell movements for invasion.

A Fully Automated High-Throughput Zebrafish Behavioral Ototoxicity Assay.

PubMed

Todd, Douglas W; Philip, Rohit C; Niihori, Maki; Ringle, Ryan A; Coyle, Kelsey R; Zehri, Sobia F; Zabala, Leanne; Mudery, Jordan A; Francis, Ross H; Rodriguez, Jeffrey J; Jacob, Abraham

2017-08-01

Zebrafish animal models lend themselves to behavioral assays that can facilitate rapid screening of ototoxic, otoprotective, and otoregenerative drugs. Structurally similar to human inner ear hair cells, the mechanosensory hair cells on their lateral line allow the zebrafish to sense water flow and orient head-to-current in a behavior called rheotaxis. This rheotaxis behavior deteriorates in a dose-dependent manner with increased exposure to the ototoxin cisplatin, thereby establishing itself as an excellent biomarker for anatomic damage to lateral line hair cells. Building on work by our group and others, we have built a new, fully automated high-throughput behavioral assay system that uses automated image analysis techniques to quantify rheotaxis behavior. This novel system consists of a custom-designed swimming apparatus and imaging system consisting of network-controlled Raspberry Pi microcomputers capturing infrared video. Automated analysis techniques detect individual zebrafish, compute their orientation, and quantify the rheotaxis behavior of a zebrafish test population, producing a powerful, high-throughput behavioral assay. Using our fully automated biological assay to test a standardized ototoxic dose of cisplatin against varying doses of compounds that protect or regenerate hair cells may facilitate rapid translation of candidate drugs into preclinical mammalian models of hearing loss.

Sustained transcription of the immediate early gene Arc in the dentate gyrus after spatial exploration.

PubMed

Ramirez-Amaya, Victor; Angulo-Perkins, Arafat; Chawla, Monica K; Barnes, Carol A; Rosi, Susanna

2013-01-23

After spatial exploration in rats, Arc mRNA is expressed in ∼2% of dentate gyrus (DG) granule cells, and this proportion of Arc-positive neurons remains stable for ∼8 h. This long-term presence of Arc mRNA following behavior is not observed in hippocampal CA1 pyramidal cells. We report here that in rats ∼50% of granule cells with cytoplasmic Arc mRNA, induced some hours previously during exploration, also show Arc expression in the nucleus. This suggests that recent transcription can occur long after the exploration behavior that elicited it. To confirm that the delayed nuclear Arc expression was indeed recent transcription, Actinomycin D was administered immediately after exploration. This treatment resulted in inhibition of recent Arc expression both when evaluated shortly after exploratory behavior as well as after longer time intervals. Together, these data demonstrate a unique kinetic profile for Arc transcription in hippocampal granule neurons following behavior that is not observed in other cell types. Among a number of possibilities, this sustained transcription may provide a mechanism that ensures that the synaptic connection weights in the sparse population of granule cells recruited during a given behavioral event are able to be modified.

Fuel Cell Electric Vehicle Performance Composite Data Products: Spring 2018

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

Kurtz, Jennifer M; Sprik, Samuel; Ainscough, Christopher D

This publication includes 22 composite data products (CDPs) produced in Spring 2018 for fuel cell electric vehicle performance in the categories of deployment, driving behavior, fuel economy, fueling behavior, and hydrogen performance.

Maintaining the pluripotency of mouse embryonic stem cells on gold nanoparticle layers with nanoscale but not microscale surface roughness

NASA Astrophysics Data System (ADS)

Lyu, Zhonglin; Wang, Hongwei; Wang, Yanyun; Ding, Kaiguo; Liu, Huan; Yuan, Lin; Shi, Xiujuan; Wang, Mengmeng; Wang, Yanwei; Chen, Hong

2014-05-01

Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction.Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01540a

Gallic acid modulates phenotypic behavior and gene expression in oral squamous cell carcinoma cells by interfering with leptin pathway.

PubMed

Santos, Eliane Macedo Sobrinho; da Rocha, Rogério Gonçalves; Santos, Hércules Otacílio; Guimarães, Talita Antunes; de Carvalho Fraga, Carlos Alberto; da Silveira, Luiz Henrique; Batista, Paulo Ricardo; de Oliveira, Paulo Sérgio Lopes; Melo, Geraldo Aclécio; Santos, Sérgio Henrique; de Paula, Alfredo Maurício Batista; Guimarães, André Luiz Sena; Farias, Lucyana Conceição

2018-01-01

Gallic acid is a polyphenolic compost appointed to interfere with neoplastic cells behavior. Evidence suggests an important role of leptin in carcinogenesis pathways, inducing a proliferative phenotype. We investigated the potential of gallic acid to modulate leptin-induced cell proliferation and migration of oral squamous cell carcinoma cell lines. The gallic acid effect on leptin secretion by oral squamous cell carcinoma cells, as well as the underlying molecular mechanisms, was also assessed. For this, we performed proliferation, migration, immunocytochemical and qPCR assays. The expression levels of cell migration-related genes (MMP2, MMP9, Col1A1, and E-cadherin), angiogenesis (HIF-1α, mir210), leptin signaling (LepR, p44/42 MAPK), apoptosis (casp-3), and secreted leptin levels by oral squamous cell carcinoma cells were also measured. Gallic acid decreased proliferation and migration of leptin-treated oral squamous cell carcinoma cells, and reduced mRNA expression of MMP2, MMP9, Col1A1, mir210, but did not change HIF-1α. Gallic acid decreased levels of leptin secreted by oral squamous cell carcinoma cells, accordingly with downregulation of p44/42 MAPK expression. Thus, gallic acid appears to break down neoplastic phenotype of oral squamous cell carcinoma cells by interfering with leptin pathway. Copyright © 2017 Elsevier GmbH. All rights reserved.

Single Cell Assay for Analyzing Single Cell Exosome and Endocrine Secretion and Cancer Markers

NASA Astrophysics Data System (ADS)

Chiu, Yu-Jui

To understand the inhomogeneity of cells in biological systems, there is a growing demand for the capability to characterize the properties of individual single cells. Since single cell studies require continuous monitoring of the cell behaviors instead of a snapshot test at a single time point, an effective single-cell assay that can support time lapsed studies in a high throughput manner is desired. Most currently available single-cell technologies cannot provide proper environments to sustain cell growth and cannot provide, for appropriate cell types, proliferation of single cells and convenient, non-invasive tests of single cell behaviors from molecular markers. In this dissertation, I present a highly versatile single-cell assay that can accommodate different cellular types, enable easy and efficient single cell loading and culturing, and be suitable for the study of effects of in-vitro environmental factors in combination with drug screening. The salient features of the assay are the non-invasive collection and surveying of single cell secretions at different time points and massively parallel translocation of single cells by user defined criteria, producing very high compatibility to the downstream process such as single cell qPCR and sequencing. Above all, the acquired information is quantitative -- for example, one of the studies is measured by the number of exosomes each single cell secretes for a given time period. Therefore, our single-cell assay provides a convenient, low-cost, and enabling tool for quantitative, time lapsed studies of single cell properties.

Statistical numeracy as a moderator of (pseudo)contingency effects on decision behavior.

PubMed

Fleig, Hanna; Meiser, Thorsten; Ettlin, Florence; Rummel, Jan

2017-03-01

Pseudocontingencies denote contingency estimates inferred from base rates rather than from cell frequencies. We examined the role of statistical numeracy for effects of such fallible but adaptive inferences on choice behavior. In Experiment 1, we provided information on single observations as well as on base rates and tracked participants' eye movements. In Experiment 2, we manipulated the availability of information on cell frequencies and base rates between conditions. Our results demonstrate that a focus on base rates rather than cell frequencies benefits pseudocontingency effects. Learners who are more proficient in (conditional) probability calculation prefer to rely on cell frequencies in order to judge contingencies, though, as was evident from their gaze behavior. If cell frequencies are available in summarized format, they may infer the true contingency between options and outcomes. Otherwise, however, even highly numerate learners are susceptible to pseudocontingency effects. Copyright © 2017 Elsevier B.V. All rights reserved.

Epitaxially grown collagen fibrils reveal diversity in contact guidance behavior among cancer cells.

PubMed

Wang, Juan; Petefish, Joseph W; Hillier, Andrew C; Schneider, Ian C

2015-01-01

Invasion of cancer cells into the surrounding tissue is an important step during cancer progression and is driven by cell migration. Cell migration can be random, but often it is directed by various cues such as aligned fibers composed of extracellular matrix (ECM), a process called contact guidance. During contact guidance, aligned fibers bias migration along the long axis of the fibers. These aligned fibers of ECM are commonly composed of type I collagen, an abundant structural protein around tumors. In this paper, we epitaxially grew several different patterns of organized type I collagen on mica and compared the morphology and contact guidance behavior of two invasive breast cancer cell lines (MDA-MB-231 and MTLn3 cells). Others have shown that these cells randomly migrate in qualitatively different ways. MDA-MB-231 cells exert large traction forces, tightly adhere to the ECM, and migrate with spindle-shaped morphology and thus adopt a mesenchymal mode of migration. MTLn3 cells exert small traction forces, loosely adhere to the ECM, and migrate with a more rounded morphology and thus adopt an amoeboid mode of migration. As the degree of alignment of type I collagen fibrils increases, cells become more elongated and engage in more directed contact guidance. MDA-MB-231 cells perceive the directional signal of highly aligned type I collagen fibrils with high fidelity, elongating to large extents and migrating directionally. Interestingly, behavior in MTLn3 cells differs. While highly aligned type I collagen fibril patterns facilitate spreading and random migration of MTLn3 cells, they do not support elongation or directed migration. Thus, different contact guidance cues bias cell migration differently and the fidelity of contact guidance is cell type dependent, suggesting that ECM alignment is a permissive cue for contact guidance, but requires a cell to have certain properties to interpret that cue.

Prediction of the Stress-Strain Behavior of Open-Cell Aluminum Foam under Compressive Loading and the Effects of Various RVE Boundary Conditions

NASA Astrophysics Data System (ADS)

Hamidi Ghaleh Jigh, Behrang; Farsi, Mohammad Ali; Hosseini Toudeshky, Hossein

2018-05-01

The prediction of the mechanical behavior of metallic foams with realistic microstructure and the effects of various boundary conditions on the mechanical behavior is an important and challenging issue in modeling representative volume elements (RVEs). A numerical investigation is conducted to determine the effects of various boundary conditions and cell wall cross sections on the compressive mechanical properties of aluminum foam, including the stiffness, plateau stress and onset strain of densification. The open-cell AA6101-T6 aluminum foam Duocel is used in the analyses in this study. Geometrical characteristics including the cell size, foam relative density, and cross-sectional shape and thickness of the cell walls are extracted from images of the foam. Then, the obtained foam microstructure is analyzed as a 2D model. The ligaments are modeled as shear deformable beams with elastic-plastic material behavior. To prevent interpenetration of the nodes and walls inside the cells with large deformations, self-contact-type frictionless interaction is stipulated between the internal surfaces. Sensitivity analyses are performed using several boundary conditions and cells wall cross-sectional shapes. The predicted results from the finite element analyses are compared with the experimental results. Finally, the most appropriate boundary conditions, leading to more consistent results with the experimental data, are introduced.

Prediction of the Stress-Strain Behavior of Open-Cell Aluminum Foam under Compressive Loading and the Effects of Various RVE Boundary Conditions

NASA Astrophysics Data System (ADS)

Hamidi Ghaleh Jigh, Behrang; Farsi, Mohammad Ali; Hosseini Toudeshky, Hossein

2018-04-01

The prediction of the mechanical behavior of metallic foams with realistic microstructure and the effects of various boundary conditions on the mechanical behavior is an important and challenging issue in modeling representative volume elements (RVEs). A numerical investigation is conducted to determine the effects of various boundary conditions and cell wall cross sections on the compressive mechanical properties of aluminum foam, including the stiffness, plateau stress and onset strain of densification. The open-cell AA6101-T6 aluminum foam Duocel is used in the analyses in this study. Geometrical characteristics including the cell size, foam relative density, and cross-sectional shape and thickness of the cell walls are extracted from images of the foam. Then, the obtained foam microstructure is analyzed as a 2D model. The ligaments are modeled as shear deformable beams with elastic-plastic material behavior. To prevent interpenetration of the nodes and walls inside the cells with large deformations, self-contact-type frictionless interaction is stipulated between the internal surfaces. Sensitivity analyses are performed using several boundary conditions and cells wall cross-sectional shapes. The predicted results from the finite element analyses are compared with the experimental results. Finally, the most appropriate boundary conditions, leading to more consistent results with the experimental data, are introduced.

Cell-matrix mechanical interaction in electrospun polymeric scaffolds for tissue engineering: Implications for scaffold design and performance.

PubMed

Kennedy, Kelsey M; Bhaw-Luximon, Archana; Jhurry, Dhanjay

2017-03-01

Engineered scaffolds produced by electrospinning of biodegradable polymers offer a 3D, nanofibrous environment with controllable structural, chemical, and mechanical properties that mimic the extracellular matrix of native tissues and have shown promise for a number of tissue engineering applications. The microscale mechanical interactions between cells and electrospun matrices drive cell behaviors including migration and differentiation that are critical to promote tissue regeneration. Recent developments in understanding these mechanical interactions in electrospun environments are reviewed, with emphasis on how fiber geometry and polymer structure impact on the local mechanical properties of scaffolds, how altering the micromechanics cues cell behaviors, and how, in turn, cellular and extrinsic forces exerted on the matrix mechanically remodel an electrospun scaffold throughout tissue development. Techniques used to measure and visualize these mechanical interactions are described. We provide a critical outlook on technological gaps that must be overcome to advance the ability to design, assess, and manipulate the mechanical environment in electrospun scaffolds toward constructs that may be successfully applied in tissue engineering and regenerative medicine. Tissue engineering requires design of scaffolds that interact with cells to promote tissue development. Electrospinning is a promising technique for fabricating fibrous, biomimetic scaffolds. Effects of electrospun matrix microstructure and biochemical properties on cell behavior have been extensively reviewed previously; here, we consider cell-matrix interaction from a mechanical perspective. Micromechanical properties as a driver of cell behavior has been well established in planar substrates, but more recently, many studies have provided new insights into mechanical interaction in fibrillar, electrospun environments. This review provides readers with an overview of how electrospun scaffold mechanics and cell behavior work in a dynamic feedback loop to drive tissue development, and discusses opportunities for improved design of mechanical environments that are conducive to tissue development. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Rate of deoxygenation modulates rheologic behavior of sickle red blood cells at a given mean corpuscular hemoglobin concentration.

PubMed

Kaul, D K; Liu, X D

1999-01-01

Although the mean corpuscular hemoglobin concentration (MCHC) plays a dominant role in the rheologic behavior of deoxygenated density-defined sickle red blood cells (SS RBCs), previous studies have not explored the relationship between the rate of deoxygenation and the bulk viscosity of SS RBCs at a given MCHC. In the present study, we have subjected density-defined SS classes (i.e., medium-density SS4 and dense SS5 discocytes) to varying deoxygenation rates. This approach has allowed us to minimize the effects of SS RBC heterogeneity and investigate the effect of deoxygenation rates at a given MCHC. The results show that the percentages of granular cells, classic sickle cells and holly leaf forms in deoxygenated samples are significantly influenced by the rate of deoxygenation and the MCHC of a given discocyte subpopulation. Increasing the deoxygenation rate using high K+ medium (pH 6.8), results in a greater percentage of granular cells in SS4 suspensions, accompanied by a pronounced increase in the bulk viscosity of these cells compared with gradually deoxygenated samples (mainly classic sickle cells and holly leaf forms). The effect of MCHC becomes apparent when SS5 dense cells are subjected to varying deoxygenation rates. At a given deoxygenation rate, SS5 dense discocytes show a greater increase in the percentage of granular cells than that observed for SS4 RBCs. Also, at a given deoxygenation rate, SS5 suspensions exhibit a higher viscosity than SS4 suspensions with fast deoxygenation resulting in maximal increase in viscosity. Although MCHC is the main determinant of SS RBC rheologic behavior, these studies demonstrate for the first time that at a given MCHC, the rate of deoxygenation (hence HbS polymerization rates) further modulates the rheologic behavior of SS RBCs. Thus, both MCHC and the deoxygenation rate may contribute to microcirculatory flow behavior of SS RBCs.

Manipulating Cells with Static Magnetic Fields

NASA Astrophysics Data System (ADS)

Valles, J. M.; Guevorkian, K.

2005-07-01

We review our investigations of the use of static magnetic fields, B, for manipulating cells and cellular processes. We describe how B fields modify the cell division pattern of frog embryos and consequently can be used to probe the pattern determinants. We also observe that magnetic fields modify the swimming behavior of Paramecium Caudatum. We describe these modifications and their potential application to investigations of their swimming behavior.

A critical-like collective state leads to long-range cell communication in Dictyostelium discoideum aggregation

PubMed Central

De Palo, Giovanna; Yi, Darvin; Endres, Robert G.

2017-01-01

The transition from single-cell to multicellular behavior is important in early development but rarely studied. The starvation-induced aggregation of the social amoeba Dictyostelium discoideum into a multicellular slug is known to result from single-cell chemotaxis towards emitted pulses of cyclic adenosine monophosphate (cAMP). However, how exactly do transient, short-range chemical gradients lead to coherent collective movement at a macroscopic scale? Here, we developed a multiscale model verified by quantitative microscopy to describe behaviors ranging widely from chemotaxis and excitability of individual cells to aggregation of thousands of cells. To better understand the mechanism of long-range cell—cell communication and hence aggregation, we analyzed cell—cell correlations, showing evidence of self-organization at the onset of aggregation (as opposed to following a leader cell). Surprisingly, cell collectives, despite their finite size, show features of criticality known from phase transitions in physical systems. By comparing wild-type and mutant cells with impaired aggregation, we found the longest cell—cell communication distance in wild-type cells, suggesting that criticality provides an adaptive advantage and optimally sized aggregates for the dispersal of spores. PMID:28422986

Automated mitosis detection of stem cell populations in phase-contrast microscopy images.

PubMed

Huh, Seungil; Ker, Dai Fei Elmer; Bise, Ryoma; Chen, Mei; Kanade, Takeo

2011-03-01

Due to the enormous potential and impact that stem cells may have on regenerative medicine, there has been a rapidly growing interest for tools to analyze and characterize the behaviors of these cells in vitro in an automated and high throughput fashion. Among these behaviors, mitosis, or cell division, is important since stem cells proliferate and renew themselves through mitosis. However, current automated systems for measuring cell proliferation often require destructive or sacrificial methods of cell manipulation such as cell lysis or in vitro staining. In this paper, we propose an effective approach for automated mitosis detection using phase-contrast time-lapse microscopy, which is a nondestructive imaging modality, thereby allowing continuous monitoring of cells in culture. In our approach, we present a probabilistic model for event detection, which can simultaneously 1) identify spatio-temporal patch sequences that contain a mitotic event and 2) localize a birth event, defined as the time and location at which cell division is completed and two daughter cells are born. Our approach significantly outperforms previous approaches in terms of both detection accuracy and computational efficiency, when applied to multipotent C3H10T1/2 mesenchymal and C2C12 myoblastic stem cell populations.

Morphogenesis of the C. elegans vulva

PubMed Central

Schindler, Adam J

2012-01-01

Understanding how cells move, change shape, and alter cellular behaviors to form organs, a process termed morphogenesis, is one of the great challenges of developmental biology. Formation of the C. elegans vulva is a powerful, simple, and experimentally accessible model for elucidating how morphogenetic processes produce an organ. In the first step of vulval development, three epithelial precursor cells divide and differentiate to generate 22 cells of seven different vulval subtypes. The 22 vulval cells then rearrange from a linear array into a tube, with each of the seven cell types undergoing characteristic morphogenetic behaviours that construct the vulva. Vulval morphogenesis entails many of the same cellular activities that underlie organogenesis and tissue formation across species, including invagination, lumen formation, oriented cell divisions, cell-cell adhesion, cell migration, cell fusion, extracellular matrix remodelling and cell invasion. Studies of vulval development have led to pioneering discoveries in a number of these processes and are beginning to bridge the gap between the pathways that specify cells and their connections to morphogenetic behaviors. The simplicity of the vulva and the experimental tools available in C. elegans will continue to make vulval morphogenesis a powerful paradigm to further our understanding of the largely mysterious mechanisms that build tissues and organs. PMID:23418408

Framing spatial cognition: Neural representations of proximal and distal frames of reference and their roles in navigation

PubMed Central

Knierim, James J.; Hamilton, Derek A.

2011-01-01

The most common behavioral test of hippocampus-dependent, spatial learning and memory is the Morris water task, and the most commonly studied behavioral correlate of hippocampal neurons is the spatial specificity of place cells. Despite decades of intensive research, it is not completely understood how animals solve the water task and how place cells generate their spatially specific firing fields. Based on early work, it has become the accepted wisdom in the general neuroscience community that distal spatial cues are the primary sources of information used by animals to solve the water task (and similar spatial tasks) and by place cells to generate their spatial specificity. More recent research, along with earlier studies that were overshadowed by the emphasis on distal cues, put this common view into question by demonstrating primary influences of local cues and local boundaries on spatial behavior and place-cell firing. This paper first reviews the historical underpinnings of the “standard” view from a behavioral perspective, and then reviews newer results demonstrating that an animal's behavior in such spatial tasks is more strongly controlled by a local-apparatus frame of reference than by distal landmarks. The paper then reviews similar findings from the literature on the neurophysiological correlates of place cells and other spatially-correlated cells from related brain areas. A model is proposed by which distal cues primarily set the orientation of the animal's internal spatial coordinate system, via the head direction cell system, whereas local cues and apparatus boundaries primarily set the translation and scale of that coordinate system. PMID:22013211

A magnetic-dependent protein corona of tailor-made superparamagnetic iron oxides alters their biological behaviors

NASA Astrophysics Data System (ADS)

Liu, Ziyao; Zhan, Xiaohui; Yang, Minggang; Yang, Qi; Xu, Xianghui; Lan, Fang; Wu, Yao; Gu, Zhongwei

2016-03-01

In recent years, it is becoming increasingly evident that once nanoparticles come into contact with biological fluids, a protein corona surely forms and critically affects the biological behaviors of nanoparticles. Herein, we investigate whether the formation of protein corona on the surface of superparamagnetic iron oxides (SPIOs) is influenced by static magnetic field. Under static magnetic field, there is no obvious variation in the total amount of protein adsorption, but the proportion of adsorbed proteins significantly changes. Noticeably, certain proteins including apolipoproteins, complement system proteins and acute phase proteins, increase in the protein corona of SPIOs in the magnetic field. More importantly, the magnetic-dependent protein corona of SPIOs enhances the cellular uptake of SPIOs into the normal cell line (3T3 cells) and tumor cell line (HepG2 cells), due to increased adsorption of apolipoprotein. In addition, SPIOs with the magnetic-dependent protein corona cause high cytotoxicity to 3T3 cells and HepG2 cells. This work discloses that superparamagnetism as a key feature of SPIOs affects the composition of protein corona to a large extent, which further alters the biological behaviors of SPIOs.In recent years, it is becoming increasingly evident that once nanoparticles come into contact with biological fluids, a protein corona surely forms and critically affects the biological behaviors of nanoparticles. Herein, we investigate whether the formation of protein corona on the surface of superparamagnetic iron oxides (SPIOs) is influenced by static magnetic field. Under static magnetic field, there is no obvious variation in the total amount of protein adsorption, but the proportion of adsorbed proteins significantly changes. Noticeably, certain proteins including apolipoproteins, complement system proteins and acute phase proteins, increase in the protein corona of SPIOs in the magnetic field. More importantly, the magnetic-dependent protein corona of SPIOs enhances the cellular uptake of SPIOs into the normal cell line (3T3 cells) and tumor cell line (HepG2 cells), due to increased adsorption of apolipoprotein. In addition, SPIOs with the magnetic-dependent protein corona cause high cytotoxicity to 3T3 cells and HepG2 cells. This work discloses that superparamagnetism as a key feature of SPIOs affects the composition of protein corona to a large extent, which further alters the biological behaviors of SPIOs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08447d

Identification of beta-2 as a key cell adhesion molecule in PCa cell neurotropic behavior: a novel ex vivo and biophysical approach.

PubMed

Jansson, Keith H; Castillo, Deborah G; Morris, Joseph W; Boggs, Mary E; Czymmek, Kirk J; Adams, Elizabeth L; Schramm, Lawrence P; Sikes, Robert A

2014-01-01

Prostate cancer (PCa) is believed to metastasize through the blood/lymphatics systems; however, PCa may utilize the extensive innervation of the prostate for glandular egress. The interaction of PCa and its nerve fibers is observed in 80% of PCa and is termed perineural invasion (PNI). PCa cells have been observed traveling through the endoneurium of nerves, although the underlying mechanisms have not been elucidated. Voltage sensitive sodium channels (VSSC) are multimeric transmembrane protein complexes comprised of a pore-forming α subunit and one or two auxiliary beta (β) subunits with inherent cell adhesion molecule (CAM) functions. The beta-2 isoform (gene SCN2B) interacts with several neural CAMs, while interacting putatively with other prominent neural CAMs. Furthermore, beta-2 exhibits elevated mRNA and protein levels in highly metastatic and castrate-resistant PCa. When overexpressed in weakly aggressive LNCaP cells (2BECFP), beta-2 alters LNCaP cell morphology and enhances LNCaP cell metastasis associated behavior in vitro. We hypothesize that PCa cells use beta-2 as a CAM during PNI and subsequent PCa metastasis. The objective of this study was to determine the effect of beta-2 expression on PCa cell neurotropic metastasis associated behavior. We overexpressed beta-2 as a fusion protein with enhanced cyan fluorescence protein (ECFP) in weakly aggressive LNCaP cells and observed neurotropic effects utilizing our novel ex vivo organotypic spinal cord co-culture model, and performed functional assays with neural matrices and atomic force microscopy. With increased beta-2 expression, PCa cells display a trend of enhanced association with nerve axons. On laminin, a neural CAM, overexpression of beta-2 enhances PCa cell migration, invasion, and growth. 2BECFP cells exhibit marked binding affinity to laminin relative to LNECFP controls, and recombinant beta-2 ectodomain elicits more binding events to laminin than BSA control. Functional overexpression of VSSC beta subunits in PCa may mediate PCa metastatic behavior through association with neural matrices.

A co-culture device with a tunable stiffness to understand combinatorial cell-cell and cell-matrix interactions.

PubMed

Rao, Nikhil; Grover, Gregory N; Vincent, Ludovic G; Evans, Samantha C; Choi, Yu Suk; Spencer, Katrina H; Hui, Elliot E; Engler, Adam J; Christman, Karen L

2013-11-01

Cell behavior on 2-D in vitro cultures is continually being improved to better mimic in vivo physiological conditions by combining niche cues including multiple cell types and substrate stiffness, which are well known to impact cell phenotype. However, no system exists in which a user can systematically examine cell behavior on a substrate with a specific stiffness (elastic modulus) in culture with a different cell type, while maintaining distinct cell populations. We demonstrate the modification of a silicon reconfigurable co-culture system with a covalently linked hydrogel of user-defined stiffness. This device allows the user to control whether two separate cell populations are in contact with each other or only experience paracrine interactions on substrates of controllable stiffness. To illustrate the utility of this device, we examined the role of substrate stiffness combined with myoblast co-culture on adipose derived stem cell (ASC) differentiation and found that the presence of myoblasts and a 10 kPa substrate stiffness increased ASC myogenesis versus co-culture on stiff substrates. As this example highlights, this technology better controls the in vitro microenvironment, allowing the user to develop a more thorough understanding of the combined effects of cell-cell and cell-matrix interactions.

Videomicroscopic extraction of specific information on cell proliferation and migration in vitro

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

Debeir, Olivier; Megalizzi, Veronique; Warzee, Nadine

2008-10-01

In vitro cell imaging is a useful exploratory tool for cell behavior monitoring with a wide range of applications in cell biology and pharmacology. Combined with appropriate image analysis techniques, this approach has been shown to provide useful information on the detection and dynamic analysis of cell events. In this context, numerous efforts have been focused on cell migration analysis. In contrast, the cell division process has been the subject of fewer investigations. The present work focuses on this latter aspect and shows that, in complement to cell migration data, interesting information related to cell division can be extracted frommore » phase-contrast time-lapse image series, in particular cell division duration, which is not provided by standard cell assays using endpoint analyses. We illustrate our approach by analyzing the effects induced by two sigma-1 receptor ligands (haloperidol and 4-IBP) on the behavior of two glioma cell lines using two in vitro cell models, i.e., the low-density individual cell model and the high-density scratch wound model. This illustration also shows that the data provided by our approach are suggestive as to the mechanism of action of compounds, and are thus capable of informing the appropriate selection of further time-consuming and more expensive biological evaluations required to elucidate a mechanism.« less

Global Representations of Goal-Directed Behavior in Distinct Cell Types of Mouse Neocortex

PubMed Central

Allen, William E.; Kauvar, Isaac V.; Chen, Michael Z.; Richman, Ethan B.; Yang, Samuel J.; Chan, Ken; Gradinaru, Viviana; Deverman, Benjamin E.; Luo, Liqun; Deisseroth, Karl

2017-01-01

SUMMARY The successful planning and execution of adaptive behaviors in mammals may require long-range coordination of neural networks throughout cerebral cortex. The neuronal implementation of signals that could orchestrate cortex-wide activity remains unclear. Here, we develop and apply methods for cortex-wide Ca2+ imaging in mice performing decision-making behavior and identify a global cortical representation of task engagement encoded in the activity dynamics of both single cells and superficial neuropil distributed across the majority of dorsal cortex. The activity of multiple molecularly defined cell types was found to reflect this representation with type-specific dynamics. Focal optogenetic inhibition tiled across cortex revealed a crucial role for frontal cortex in triggering this cortex-wide phenomenon; local inhibition of this region blocked both the cortex-wide response to task-initiating cues and the voluntary behavior. These findings reveal cell-type-specific processes in cortex for globally representing goal-directed behavior and identify a major cortical node that gates the global broadcast of task-related information. PMID:28521139

In Vivo Analysis of Alternative Modes of Breast Cancer Cell Invasion

DTIC Science & Technology

2008-05-01

characterized in 3-D culture by time-lapse videomicroscopy . Bright field time-lapse videomicroscopy revealed that the MMTV-neu cells moved as both rounded...intricacies of cell signalling, and the role that cell signalling pathways play in tumor cell behavior. Working with 3-D gels and time-lapse videomicroscopy

A PDMS Device Coupled with Culture Dish for In Vitro Cell Migration Assay.

PubMed

Lv, Xiaoqing; Geng, Zhaoxin; Fan, Zhiyuan; Wang, Shicai; Pei, WeiHua; Chen, Hongda

2018-04-30

Cell migration and invasion are important factors during tumor progression and metastasis. Wound-healing assay and the Boyden chamber assay are efficient tools to investigate tumor development because both of them could be applied to measure cell migration rate. Therefore, a simple and integrated polydimethylsiloxane (PDMS) device was developed for cell migration assay, which could perform quantitative evaluation of cell migration behaviors, especially for the wound-healing assay. The integrated device was composed of three units, which included cell culture dish, PDMS chamber, and wound generation mold. The PDMS chamber was integrated with cell culture chamber and could perform six experiments under different conditions of stimuli simultaneously. To verify the function of this device, it was utilized to explore the tumor cell migration behaviors under different concentrations of fetal bovine serum (FBS) and transforming growth factor (TGF-β) at different time points. This device has the unique capability to create the "wound" area in parallel during cell migration assay and provides a simple and efficient platform for investigating cell migration assay in biomedical application.

Deconstructing (and reconstructing) cell migration.

PubMed

Maheshwari, G; Lauffenburger, D A

1998-12-01

An overriding objective in cell biology is to be able to relate properties of particular molecular components to cell behavioral functions and even physiology. In the "traditional" mode of molecular cell biology, this objective has been tackled on a molecule-by-molecule basis, and in the "future" mode sometimes termed "functional genomics," it might be attacked in a high-throughput, parallel manner. Regardless of the manner of approach, the relationship between molecular-level properties and cell-level function is exceedingly difficult to elucidate because of the large number of relevant components involved, their high degree of interconnectedness, and the inescapable fact that they operate as physico-chemical entities-according to the laws of kinetics and mechanics-in space and time within the cell. Cell migration is a prominent representative example of such a cell behavioral function that requires increased understanding for both scientific and technological advance. This article presents a framework, derived from an engineering perspective regarding complex systems, intended to aid in developing improved understanding of how properties of molecular components influence the function of cell migration. That is, cell population migration behavior can be deconstructed as follows: first in terms of a mathematical model comprising cell population parameters (random motility, chemotaxis/haptotaxis, and chemokinesis/haptokinesis coefficients), which in turn depend on characteristics of individual cell paths that can be analyzed in terms of a mathematical model comprising individual cell parameters (translocation speed, directional persistence time, chemotactic/haptotactic index), which in turn depend on cell-level physical processes underlying motility (membrane extension and retraction, cell/substratum adhesion, cell contractile force, front-vs.-rear asymmetry), which in turn depend on molecular-level properties of the plethora of components involved in governance and regulation of these processes. Hence, the influence of any molecular component on cell population migration can be understood by reconstructing these relationships from the molecular level to the physical process level to the individual cell path level to the cell population distribution level. This approach requires combining experimental, theoretical, and computational methodologies from molecular biology, biochemistry, biophysics, and bioengineering.

Brain, Behavior, and Immunity: Biobehavioral influences on recovery following hematopoietic stem cell transplantation

Cancer.gov

Review of hematopoietic stem cell transplantation and its potential “window of opportunity” during which interventions targeting stress-related behavioral factors can influence the survival, health, and well-being of recipients.

Biomechanics of Tetrahymena escaping from dead ends

NASA Astrophysics Data System (ADS)

Ishikawa, Takuji; Kikuchi, Kenji

2017-11-01

Behaviors of swimming microorganisms in complex environments are important in understanding cells' distribution in nature and in industries. Although cell's swimming and spreading in an infinite fluid has been intensively investigated, that in a narrow region bounded by walls is still unclear. Thus, in this study, we used Tetrahymena thermophila as a model microorganism, and experimentally investigated its behavior between flat plates with an angle. The results showed that the cells tended to escape from the narrow region, and the swimming velocity and the radius of curvature of the trajectories decreased as they swam narrower region. We then developed a computational model of swimming Tetrahymena. The results showed that the escaping behavior could be well explained by fluid mechanics. The obtained knowledge is useful in understanding cells' behaviors in complex environments, such as in porous media and in a granular matter. This research was supported by JSPS KAKENHI Grants, numbers 25000008 and 17H00853.

Impact of cycling at low temperatures on the safety behavior of 18650-type lithium ion cells: Combined study of mechanical and thermal abuse testing accompanied by post-mortem analysis

NASA Astrophysics Data System (ADS)

Friesen, Alex; Horsthemke, Fabian; Mönnighoff, Xaver; Brunklaus, Gunther; Krafft, Roman; Börner, Markus; Risthaus, Tim; Winter, Martin; Schappacher, Falko M.

2016-12-01

The impact of cycling at low temperatures on the thermal and mechanical abuse behavior of commercial 18650-type lithium ion cells was compared to fresh cells. Post-mortem analyses revealed a deposition of high surface area lithium (HSAL) metal on the graphite surface accompanied by severe electrolyte decomposition. Heat wait search (HWS) tests in an accelerating rate calorimeter (ARC) were performed to investigate the thermal abuse behavior of aged and fresh cells under quasi-adiabatic conditions, showing a strong shift of the onset temperature for exothermic reactions. HSAL deposition promotes the reduction of the carbonate based electrolyte due to the high reactivity of lithium metal with high surface area, leading to a thermally induced decomposition of the electrolyte to produce volatile gaseous products. Nail penetration tests showed a change in the thermal runaway (TR) behavior affected by the decomposition reaction. This study indicates a greater thermal hazard for LIB cells at higher SOC and experiencing aging at low temperature.

Behavior of Xeno-Transplanted Undifferentiated Human Induced Pluripotent Stem Cells Is Impacted by Microenvironment Without Evidence of Tumors.

PubMed

Martínez-Cerdeño, Veronica; Barrilleaux, Bonnie L; McDonough, Ashley; Ariza, Jeanelle; Yuen, Benjamin T K; Somanath, Priyanka; Le, Catherine T; Steward, Craig; Horton-Sparks, Kayla; Knoepfler, Paul S

2017-10-01

Human pluripotent stem cells (hPSC) have great clinical potential through the use of their differentiated progeny, a population in which there is some concern over risks of tumorigenicity or other unwanted cellular behavior due to residual hPSC. Preclinical studies using human stem cells are most often performed within a xenotransplant context. In this study, we sought to measure how undifferentiated hPSC behave following xenotransplant. We directly transplanted undifferentiated human induced pluripotent stem cells (hIPSC) and human embryonic stem cells (hESC) into the adult mouse brain ventricle and analyzed their fates. No tumors or precancerous lesions were present at more than one year after transplantation. This result differed with the tumorigenic capacity we observed after allotransplantation of mouse ESC into the mouse brain. A substantial population of cellular derivatives of undifferentiated hESC and hIPSC engrafted, survived, and migrated within the mouse brain parenchyma. Within brain structures, transplanted cell distribution followed a very specific pattern, suggesting the existence of distinct microenvironments that offer different degrees of permissibility for engraftment. Most of the transplanted hESC and hIPSC that developed into brain cells were NeuN+ neuronal cells, and no astrocytes were detected. Substantial cell and nuclear fusion occurred between host and transplanted cells, a phenomenon influenced by microenvironment. Overall, hIPSC appear to be largely functionally equivalent to hESC in vivo. Altogether, these data bring new insights into the behavior of stem cells without prior differentiation following xenotransplantation into the adult brain.

Extracellular matrix biomimicry for the creation of investigational and therapeutic devices.

PubMed

Pellowe, Amanda S; Gonzalez, Anjelica L

2016-01-01

The extracellular matrix (ECM) is a web of fibrous proteins that serves as a scaffold for tissues and organs, and is important for maintaining homeostasis and facilitating cellular adhesion. Integrin transmembrane receptors are the primary adhesion molecules that anchor cells to the ECM, thus integrating cells with their microenvironments. Integrins play a critical role in facilitating cell-matrix interactions and promoting signal transduction, both from the cell to the ECM and vice versa, ultimately mediating cell behavior. For this reason, many advanced biomaterials employ biomimicry by replicating the form and function of fibrous ECM proteins. The ECM also acts as a reservoir for small molecules and growth factors, wherein fibrous proteins directly bind and present these bioactive moieties that facilitate cell activity. Therefore biomimicry can be enhanced by incorporating small molecules into ECM-like substrates. Biomimetic ECM materials have served as invaluable research tools for studying interactions between cells and the surrounding ECM, revealing that cell-matrix signaling is driven by mechanical forces, integrin engagement, and small molecules. Mimicking pathological ECMs has also elucidated disease specific cell behaviors. For example, biomimetic tumor microenvironments have been used to induce metastatic cell behaviors, and have thereby shown promise for in vitro cancer drug testing and targeting. Further, ECM-like substrates have been successfully employed for autologous cell recolonization for tissue engineering and wound healing. As we continue to learn more about the mechanical and biochemical characteristics of the ECM, these properties can be harnessed to develop new biomaterials, biomedical devices, and therapeutics. © 2015 Wiley Periodicals, Inc.

Cross-stream distribution of red blood cells in sickle-cell disease

NASA Astrophysics Data System (ADS)

Zhang, Xiao; Lam, Wilbur; Graham, Michael

2017-11-01

Experiments revealed that in blood flow, red blood cells (RBCs) tend to migrate away from the vessel walls, leaving a cell-free layer near the walls, while leukocytes and platelets tend to marginate towards the vessel walls. This segregation behavior of different cellular components in blood flow can be driven by their differences in stiffness and shape. An alteration of this segregation behavior may explain endothelial dysfunction and pain crisis associated with sickle-cell disease (SCD). It is hypothesized that the sickle RBCs, which are considerably stiffer than the healthy RBCs, may marginate towards the vessel walls and exert repeated damage to the endothelial cells. Direct simulations are performed to study the flowing suspensions of deformable biconcave discoids and stiff sickles representing healthy and sickle cells, respectively. It is observed that the sickles exhibit a strong margination towards the walls. The biconcave discoids in flowing suspensions undergo a so-called tank-treading motion, while the sickles behave as rigid bodies and undergo a tumbling motion. The margination behavior and tumbling motion of the sickles may help substantiate the aforementioned hypothesis of the mechanism for the SCD complications and shed some light on the design of novel therapies.

Formula For Evaluation Of Nickel/Hydrogen Cells

NASA Technical Reports Server (NTRS)

Leibecki, Harold F.

1988-01-01

Displays complete discharge curves showing changes in behavior of each cell during life and difference among cells. Equation developed to give quantitative relationship among voltage-versus-time discharge curves.

Increased expression of CD44 is associated with more aggressive behavior in clear cell renal cell carcinoma.

PubMed

Zanjani, Leili Saeednejad; Madjd, Zahra; Abolhasani, Maryam; Rasti, Arezoo; Fodstad, Oystein; Andersson, Yvonne; Asgari, Mojgan

2018-01-01

Although CD44 has been suggested as a prognostic marker in renal cell carcinoma (RCC), the prognostic significance of this marker in three main subtypes of RCC is still unclear. Thus, the present study was conducted to evaluate the expression and prognostic significance of CD44 as a cancer stem cell marker in different histological subtypes of RCC. Methodology & results: CD44 expression was evaluated in 206 well-defined renal tumor samples using immunohistochemistry on tissue microarrays. Higher CD44 expression was associated with more aggressive behavior, tumor progression and worse prognosis in clear cell RCC (ccRCC) but not in papillary and chromophobe RCC subtypes. Cancer stem cell marker CD44 may be a promising target for cancer treatment only in ccRCC.

Follow-the-leader cell migration requires biased cell-cell contact and local microenvironmental signals

NASA Astrophysics Data System (ADS)

Wynn, Michelle L.; Rupp, Paul; Trainor, Paul A.; Schnell, Santiago; Kulesa, Paul M.

2013-06-01

Directed cell migration often involves at least two types of cell motility that include multicellular streaming and chain migration. However, what is unclear is how cell contact dynamics and the distinct microenvironments through which cells travel influence the selection of one migratory mode or the other. The embryonic and highly invasive neural crest (NC) are an excellent model system to study this question since NC cells have been observed in vivo to display both of these types of cell motility. Here, we present data from tissue transplantation experiments in chick and in silico modeling that test our hypothesis that cell contact dynamics with each other and the microenvironment promote and sustain either multicellular stream or chain migration. We show that when premigratory cranial NC cells (at the pre-otic level) are transplanted into a more caudal region in the head (at the post-otic level), cells alter their characteristic stream behavior and migrate in chains. Similarly, post-otic NC cells migrate in streams after transplantation into the pre-otic hindbrain, suggesting that local microenvironmental signals dictate the mode of NC cell migration. Simulations of an agent-based model (ABM) that integrates the NC cell behavioral data predict that chain migration critically depends on the interplay of biased cell-cell contact and local microenvironment signals. Together, this integrated modeling and experimental approach suggests new experiments and offers a powerful tool to examine mechanisms that underlie complex cell migration patterns.

Surface free energy predominates in cell adhesion to hydroxyapatite through wettability.

PubMed

Nakamura, Miho; Hori, Naoko; Ando, Hiroshi; Namba, Saki; Toyama, Takeshi; Nishimiya, Nobuyuki; Yamashita, Kimihiro

2016-05-01

The initial adhesion of cells to biomaterials is critical in the regulation of subsequent cell behaviors. The purpose of this study was to investigate a mechanism through which the surface wettability of biomaterials can be improved and determine the effects of biomaterial surface characteristics on cellular behaviors. We investigated the surface characteristics of various types of hydroxyapatite after sintering in different atmospheres and examined the effects of various surface characteristics on cell adhesion to study cell-biomaterial interactions. Sintering atmosphere affects the polarization capacity of hydroxyapatite by changing hydroxide ion content and grain size. Compared with hydroxyapatite sintered in air, hydroxyapatite sintered in saturated water vapor had a higher polarization capacity that increased surface free energy and improved wettability, which in turn accelerated cell adhesion. We determined the optimal conditions of hydroxyapatite polarization for the improvement of surface wettability and acceleration of cell adhesion. Copyright © 2016 Elsevier B.V. All rights reserved.

Systematic Analysis of the Transcriptional Switch Inducing Migration of Border Cells

PubMed Central

Borghese, Lodovica; Fletcher, Georgina; Mathieu, Juliette; Atzberger, Ann; Eades, William C.; Cagan, Ross L.; Rørth, Pernille

2010-01-01

Summary Cell migration within a natural context is tightly controlled, often by specific transcription factors. However, the switch from stationary to migratory behavior is poorly understood. Border cells perform a spatially and temporally controlled invasive migration during Drosophila oogenesis. Slbo, a C/EBP family transcriptional activator, is required for them to become migratory. We purified wild-type and slbo mutant border cells as well as nonmigratory follicle cells and performed comparative whole-genome expression profiling, followed by functional tests of the contributions of identified targets to migration. About 300 genes were significantly upregulated in border cells, many dependent on Slbo. Among these, the microtubule regulator Stathmin was strongly upregulated and was required for normal migration. Actin cytoskeleton regulators were also induced, including, surprisingly, a large cluster of “muscle-specific” genes. We conclude that Slbo induces multiple cytoskeletal effectors, and that each contributes to the behavioral changes in border cells. PMID:16580994

Socializing with MYC: cell competition in development and as a model for premalignant cancer.

PubMed

Johnston, Laura A

2014-04-01

Studies in Drosophila and mammals have made it clear that genetic mutations that arise in somatic tissues are rapidly recognized and eliminated, suggesting that cellular fitness is tightly monitored. During development, damaged, mutant, or otherwise unfit cells are prevented from contributing to the tissue and are instructed to die, whereas healthy cells benefit and populate the animal. This cell selection process, known as cell competition, eliminates somatic genetic heterogeneity and promotes tissue fitness during development. Yet cell competition also has a dark side. Super competition can be exploited by incipient cancers to subvert cellular cooperation and promote selfish behavior. Evidence is accumulating that MYC plays a key role in regulation of social behavior within tissues. Given the high number of tumors with deregulated MYC, studies of cell competition promise to yield insight into how the local environment yields to and participates in the early stages of tumor formation.

Hippocampal awake replay in fear memory retrieval

PubMed Central

Wu, Chun-Ting; Haggerty, Daniel; Kemere, Caleb; Ji, Daoyun

2017-01-01

Hippocampal place cells are key to episodic memories. How these cells participate in memory retrieval remains unclear. Here, after rats acquired a fear memory by receiving mild foot-shocks at a shock zone of a track, we analyzed place cells when the animals were placed back to the track and displayed an apparent memory retrieval behavior: avoidance of the shock zone. We found that place cells representing the shock zone were reactivated, despite the fact that the animals did not enter the shock zone. This reactivation occurred in ripple-associated awake replay of place cell sequences encoding the paths from the animal’s current positions to the shock zone, but not in place cell sequences within individual cycles of theta oscillation. The result reveals a specific place cell pattern underlying the inhibitory avoidance behavior and provides strong evidence for the involvement of awake replay in fear memory retrieval. PMID:28218916

γδT cells but not αβT cells contribute to sepsis-induced white matter injury and motor abnormalities in mice.

PubMed

Zhang, Xiaoli; Rocha-Ferreira, Eridan; Li, Tao; Vontell, Regina; Jabin, Darakhshan; Hua, Sha; Zhou, Kai; Nazmi, Arshed; Albertsson, Anna-Maj; Sobotka, Kristina; Ek, Joakim; Thornton, Claire; Hagberg, Henrik; Mallard, Carina; Leavenworth, Jianmei W; Zhu, Changlian; Wang, Xiaoyang

2017-12-20

Infection and sepsis are associated with brain white matter injury in preterm infants and the subsequent development of cerebral palsy. In the present study, we used a neonatal mouse sepsis-induced white matter injury model to determine the contribution of different T cell subsets (αβT cells and γδT cells) to white matter injury and consequent behavioral changes. C57BL/6J wild-type (WT), T cell receptor (TCR) δ-deficient (Tcrd -/- , lacking γδT cells), and TCRα-deficient (Tcra -/- , lacking αβT cells) mice were administered with lipopolysaccharide (LPS) at postnatal day (PND) 2. Brain myelination was examined at PNDs 12, 26, and 60. Motor function and anxiety-like behavior were evaluated at PND 26 or 30 using DigiGait analysis and an elevated plus maze. White matter development was normal in Tcrd -/- and Tcrα -/- compared to WT mice. LPS exposure induced reductions in white matter tissue volume in WT and Tcrα -/- mice, but not in the Tcrd -/- mice, compared with the saline-treated groups. Neither LPS administration nor the T cell deficiency affected anxiety behavior in these mice as determined with the elevated plus maze. DigiGait analysis revealed motor function deficiency after LPS-induced sepsis in both WT and Tcrα -/- mice, but no such effect was observed in Tcrd -/- mice. Our results suggest that γδT cells but not αβT cells contribute to sepsis-induced white matter injury and subsequent motor function abnormalities in early life. Modulating the activity of γδT cells in the early stages of preterm white matter injury might represent a novel therapeutic strategy for the treatment of perinatal brain injury.

Behavior of HepG2 liver cancer cells using microfluidic-microscopy: a preliminary study

NASA Astrophysics Data System (ADS)

Karamahmutoglu, Hande; ćetin, Metin; Yaǧcı, Tamer; Elitaş, Meltem

2018-02-01

Hepatocellular carcinoma is one of the most common types of liver cancer causing death all over the world. Although early-stage liver cancer can sometimes be treated with partial hepatectomy, liver transplantation, ablation, and embolization, sorafenib treatment is the only approved systemic therapy for advanced HCC. The aim of this research is to develop tools and methods to understand the individuality of hepatocellular carcinoma. Microfluidic cell-culture platform has been developed to observe behavior of single-cells; fluorescence microscopy has been implemented to investigate phenotypic changes of cells. Our preliminary data proved high-level heterogeneity of hepatocellular carcinoma while verifying limited growth of liver cancer cell lines on the silicon wafer.

Quantitative analysis of osteoblast behavior on microgrooved hydroxyapatite and titanium substrata.

PubMed

Lu, Xiong; Leng, Yang

2003-09-01

The effects of implant surface topography and chemistry on osteoblast behavior have been a research focus because of their potential importance in orthopedic and dental applications. This work focused on the topographic effects of hydroxyapatite (HA) and titanium (Ti) surface that had identical micropatterns to determine whether there was synergistic interaction between surface chemistry and surface topography. Surface microgrooves with six different groove widths (4, 8, 16, 24, 30, and 38 microm) and three different groove depths (2, 4, and 10 microm) were made on single crystalline silicon wafers using microfabrication techniques. Ti and HA thin films were coated on the microgrooves by radio-frequency magnetron sputtering. After that, human osteoblast-like cells were seeded and cultured on the microgrooved surfaces for up to 7 days. The cells' behavior was examined using scanning electron microscopy after cells were fixed and dehydrated. Statistical analysis was based on quantitative data of orientation angle, evaluating the contact guidance, and form index, describing cell shape or cell morphology changes. The contact guidance and cell shape changes were observed on the HA and Ti microgrooves. No difference in orientation angle between HA and Ti microgrooves was found. This might suggest that surface chemistry was not a significant influence on cell guidance. However, the form index analysis indicated an interaction between topographic effects and surface chemistry. Thus, conclusions about surface topographic effects on cell behavior drawn from one type of material cannot simply be applied to another type of material. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 677-687, 2003

Spontaneous locomotor activity correlates with the degranulation of mast cells in the meninges rather than in the thalamus: Disruptive effect of cocaine

PubMed Central

Larson, Alice A.; Thomas, Mark J.; McElhose, Alex; Kovács, Katalin J.

2011-01-01

Mast cells are located in the central nervous system (CNS) of many mammals and stress induces their degranulation. We postulated that mast cells are associated with wakefulness and stimulatory tone in the CNS, as reflected by spontaneous motor activity. Because stress also precipitates drug-seeking behavior in cocaine addicts, we also postulated that cocaine manifests its effects through this relationship. We investigated the influence of single and repeated injections of cocaine on circulating corticosterone, motor activity and degranulation of mast cells in both the thalamus and meninges of mice. Mice were subjected to 5 consecutive days of cocaine or saline followed by a single injection of cocaine or saline 11 days later. Spontaneous locomotor activity was measure for one hour after the final injection before death. Neither a single injection nor prior treatment with cocaine increased motor activity compared to saline-injected controls, however, repeated administration of cocaine induced a significant sensitization to its behavioral effect when delivered 11 days later. In mice that received only saline, motor activity correlated positively with mast cell degranulation in the meninges but not in the thalamus. Cocaine, regardless of the treatment schedule, disrupted this correlation. The concentration of corticosterone did not differ amongst groups and did not correlate with either behavior or mast cell parameters in any group. The correlation between behavioral activity and the mast cell degranulation in the meninges suggests that these parameters are linked. The disruptive effect of cocaine on this relationship indicates a role downstream from mast cells in the regulation of motor activity. PMID:21561602

Defining Tumor Cell and Immune Cell Behavior in Vivo during Pulmonary Metastasis of Breast Cancer

DTIC Science & Technology

2014-09-01

outcome of which is still to be determined. 15. SUBJECT TERMS Lung Metastasis, Intravital Imaging , Tumor Immunology, Tumor Microparticles 16. SECURITY...metastatic fitness in the lung. 2) KEYWORDS: Metastasis, Intravital Imaging , Lung, Breast Cancer, 3) ACCOMPLISHMENTS: What were the major goals of the... intravital imaging of Lung Metastasis b) Characterization of Tumor Cell Behavior During Pulmonary Seeding via 2-photon microscopy c) Characterization of

Using Transgenic Zebrafish to Study Muscle Stem/Progenitor Cells.

PubMed

Nguyen, Phong D; Currie, Peter D

2017-01-01

Understanding muscle stem cell behaviors can potentially provide insights into how these cells act and respond during normal growth and diseased contexts. The zebrafish is an ideal model organism to examine these behaviors in vivo where it would normally be technically challenging in other mammalian models. This chapter will describe the procedures required to successfully conduct live imaging of zebrafish transgenics that has specifically been adapted for skeletal muscle.

Mechanism for Collective Cell Alignment in Myxococcus xanthus Bacteria

PubMed Central

Balagam, Rajesh; Igoshin, Oleg A.

2015-01-01

Myxococcus xanthus cells self-organize into aligned groups, clusters, at various stages of their lifecycle. Formation of these clusters is crucial for the complex dynamic multi-cellular behavior of these bacteria. However, the mechanism underlying the cell alignment and clustering is not fully understood. Motivated by studies of clustering in self-propelled rods, we hypothesized that M. xanthus cells can align and form clusters through pure mechanical interactions among cells and between cells and substrate. We test this hypothesis using an agent-based simulation framework in which each agent is based on the biophysical model of an individual M. xanthus cell. We show that model agents, under realistic cell flexibility values, can align and form cell clusters but only when periodic reversals of cell directions are suppressed. However, by extending our model to introduce the observed ability of cells to deposit and follow slime trails, we show that effective trail-following leads to clusters in reversing cells. Furthermore, we conclude that mechanical cell alignment combined with slime-trail-following is sufficient to explain the distinct clustering behaviors observed for wild-type and non-reversing M. xanthus mutants in recent experiments. Our results are robust to variation in model parameters, match the experimentally observed trends and can be applied to understand surface motility patterns of other bacterial species. PMID:26308508

Microscale Bioadhesive Hydrogel Arrays for Cell Engineering Applications.

PubMed

Patel, Ravi Ghanshyam; Purwada, Alberto; Cerchietti, Leandro; Inghirami, Giorgio; Melnick, Ari; Gaharwar, Akhilesh K; Singh, Ankur

2014-09-01

Bioengineered hydrogels have been explored in cell and tissue engineering applications to support cell growth and modulate its behavior. A rationally designed scaffold should allow for encapsulated cells to survive, adhere, proliferate, remodel the niche, and can be used for controlled delivery of biomolecules. Here we report a microarray of composite bioadhesive microgels with modular dimensions, tunable mechanical properties and bulk modified adhesive biomolecule composition. Composite bioadhesive microgels of maleimide functionalized polyethylene glycol (PEG-MAL) with interpenetrating network (IPN) of gelatin ionically cross-linked with silicate nanoparticles were engineered by integrating microfabrication with Michael-type addition chemistry and ionic gelation. By encapsulating clinically relevant anchorage-dependent cervical cancer cells and suspension leukemia cells as cell culture models in these composite microgels, we demonstrate enhanced cell spreading, survival, and metabolic activity compared to control gels. The composite bioadhesive hydrogels represent a platform that could be used to study independent effect of stiffness and adhesive ligand density on cell survival and function. We envision that such microarrays of cell adhesive microenvironments, which do not require harsh chemical and UV crosslinking conditions, will provide a more efficacious cell culture platform that can be used to study cell behavior and survival, function as building blocks to fabricate 3D tissue structures, cell delivery systems, and high throughput drug screening devices.

Microscale Bioadhesive Hydrogel Arrays for Cell Engineering Applications

PubMed Central

PATEL, RAVI GHANSHYAM; PURWADA, ALBERTO; CERCHIETTI, LEANDRO; INGHIRAMI, GIORGIO; MELNICK, ARI; GAHARWAR, AKHILESH K.; SINGH, ANKUR

2014-01-01

Bioengineered hydrogels have been explored in cell and tissue engineering applications to support cell growth and modulate its behavior. A rationally designed scaffold should allow for encapsulated cells to survive, adhere, proliferate, remodel the niche, and can be used for controlled delivery of biomolecules. Here we report a microarray of composite bioadhesive microgels with modular dimensions, tunable mechanical properties and bulk modified adhesive biomolecule composition. Composite bioadhesive microgels of maleimide functionalized polyethylene glycol (PEG-MAL) with interpenetrating network (IPN) of gelatin ionically cross-linked with silicate nanoparticles were engineered by integrating microfabrication with Michael-type addition chemistry and ionic gelation. By encapsulating clinically relevant anchorage-dependent cervical cancer cells and suspension leukemia cells as cell culture models in these composite microgels, we demonstrate enhanced cell spreading, survival, and metabolic activity compared to control gels. The composite bioadhesive hydrogels represent a platform that could be used to study independent effect of stiffness and adhesive ligand density on cell survival and function. We envision that such microarrays of cell adhesive microenvironments, which do not require harsh chemical and UV crosslinking conditions, will provide a more efficacious cell culture platform that can be used to study cell behavior and survival, function as building blocks to fabricate 3D tissue structures, cell delivery systems, and high throughput drug screening devices. PMID:25328548

Microenvironments engineered by inkjet bioprinting spatially direct adult stem cells toward muscle- and bone-like subpopulations.

PubMed

Phillippi, Julie A; Miller, Eric; Weiss, Lee; Huard, Johnny; Waggoner, Alan; Campbell, Phil

2008-01-01

In vivo, growth factors exist both as soluble and as solid-phase molecules, immobilized to cell surfaces and within the extracellular matrix. We used this rationale to develop more biologically relevant approaches to study stem cell behaviors. We engineered stem cell microenvironments using inkjet bioprinting technology to create spatially defined patterns of immobilized growth factors. Using this approach, we engineered cell fate toward the osteogenic lineage in register to printed patterns of bone morphogenetic protein (BMP) 2 contained within a population of primary muscle-derived stem cells (MDSCs) isolated from adult mice. This patterning approach was conducive to patterning the MDSCs into subpopulations of osteogenic or myogenic cells simultaneously on the same chip. When cells were cultured under myogenic conditions on BMP-2 patterns, cells on pattern differentiated toward the osteogenic lineage, whereas cells off pattern differentiated toward the myogenic lineage. Time-lapse microscopy was used to visualize the formation of multinucleated myotubes, and immunocytochemistry was used to demonstrate expression of myosin heavy chain (fast) in cells off BMP-2 pattern. This work provides proof-of-concept for engineering spatially controlled multilineage differentiation of stem cells using patterns of immobilized growth factors. This approach may be useful for understanding cell behaviors to immobilized biological patterns and could have potential applications for regenerative medicine.

Thermal characterizations of a large-format lithium ion cell focused on high current discharges

NASA Astrophysics Data System (ADS)

Veth, C.; Dragicevic, D.; Merten, C.

2014-12-01

The thermal behavior of a large-format lithium ion cell has been investigated during measurements on cell and battery level. High current discharges up to 300 A are the main topic of this study. This paper demonstrates that the temperature response to high current loads provides the possibility to investigate internal cell parameters and their inhomogeneity. In order to identify thermal response caused by internal cell processes, the heat input due to contact resistances has been minimized. The differences between the thermal footprint of a cell during cell and battery measurements are being addressed. The study presented here focuses on the investigation of thermal hot and cold spots as well as temperature gradients in a 50 Ah pouch cell. Furthermore, it is demonstrated that the difference between charge and discharge can have significant influence on the thermal behavior of lithium ion cells. Moreover, the miscellaneous thermal characteristics of differently aged lithium ion cells highlight the possibility of an ex-situ non-destructive post-mortem-analysis, providing the possibility of a qualitative and quantitative characterization of inhomogeneous cell-aging. These investigations also generate excellent data for the validation and parameterization of electro-thermal cell models, predicting the distribution of temperature, current, potential, SOC and SOH inside large-format cells.

Modeling oscillations and spiral waves in Dictyostelium populations

NASA Astrophysics Data System (ADS)

Noorbakhsh, Javad; Schwab, David J.; Sgro, Allyson E.; Gregor, Thomas; Mehta, Pankaj

2015-06-01

Unicellular organisms exhibit elaborate collective behaviors in response to environmental cues. These behaviors are controlled by complex biochemical networks within individual cells and coordinated through cell-to-cell communication. Describing these behaviors requires new mathematical models that can bridge scales—from biochemical networks within individual cells to spatially structured cellular populations. Here we present a family of "multiscale" models for the emergence of spiral waves in the social amoeba Dictyostelium discoideum. Our models exploit new experimental advances that allow for the direct measurement and manipulation of the small signaling molecule cyclic adenosine monophosphate (cAMP) used by Dictyostelium cells to coordinate behavior in cellular populations. Inspired by recent experiments, we model the Dictyostelium signaling network as an excitable system coupled to various preprocessing modules. We use this family of models to study spatially unstructured populations of "fixed" cells by constructing phase diagrams that relate the properties of population-level oscillations to parameters in the underlying biochemical network. We then briefly discuss an extension of our model that includes spatial structure and show how this naturally gives rise to spiral waves. Our models exhibit a wide range of novel phenomena. including a density-dependent frequency change, bistability, and dynamic death due to slow cAMP dynamics. Our modeling approach provides a powerful tool for bridging scales in modeling of Dictyostelium populations.

The swimming behavior of flagellated bacteria in viscous and viscoelastic media

NASA Astrophysics Data System (ADS)

Qu, Zijie; Henderikx, Rene; Breuer, Kenneth

2016-11-01

The motility of bacteria E.coli in viscous and viscoelastic fluids has been widely studied although full understanding remains elusive. The swimming mode of wild-type E.coli is well-described by a run-and-tumble sequence in which periods of straight swimming at a constant speed are randomly interrupted by a tumble, defined as a sudden change of direction with a very low speed. Using a tracking microscope, we follow cells for extended periods of time and find that the swimming behavior can be more complex, and can include a wider variety of behaviors including a "slow random walk" in which the cells move at relatively low speed without the characteristic run. Significant variation between individual cells is observed, and furthermore, a single cell can change its motility during the course of a tracking event. Changing the viscosity and viscoelasticy of the swimming media also has profound effects on the average swimming speed and run-tumble nature of the cell motility, including changing the distribution, duration of tumbling and slow random walk events. The reasons for these changes are explained using a Purcell-style resistive force model for the cell and flagellar behavior as well as model for the changes in flagellar bundling in different fluid viscosities. National Science Foundation.

The regrowth kinetic of the surviving population is independent of acute and chronic responses to temozolomide in glioblastoma cell lines

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

Silva, Andrew Oliveira, E-mail: andrewbiomed@gmail.com; Dalsin, Eloisa, E-mail: dalsineloisa@gmail.com; Onzi, Giovana Ravizzoni, E-mail: gioonzi@gmail.com

Chemotherapy acts on cancer cells by producing multiple effects on a cell population including cell cycle arrest, necrosis, apoptosis and senescence. However, often a subpopulation of cells survives and the behavior of this subpopulation, which is responsible for cancer recurrence, remains obscure. Here we investigated the in vitro short- and long-term responses of six glioblastoma cell lines to clinically relevant doses of temozolomide for 5 days followed by 23 days of recovery, mimicking the standard schedule used in glioblastoma patient for this drug. These cells presented different profiles of sensitivity to temozolomide with varying levels of cell cycle arrest, autophagymore » and senescence, followed by a regrowth of the surviving cells. The initial reduction in cell number and the subsequent regrowth was analyzed with four new parameters applied to Cumulative Population Doubling (CPD) curves that describe the overall sensitivity of the population and the characteristic of the regrowth: the relative end point CPD (RendCPD); the relative Area Under Curve (rAUC); the Relative Time to Cross a Threshold (RTCT); and the Relative Proliferation Rate (RPR). Surprisingly, the kinetics of regrowth were not predicted by the mechanisms activated after treatment nor by the acute or overall sensitivity. With this study we added new parameters that describe key responses of glioblastoma cell populations to temozolomide treatment. These parameters can also be applied to other cell types and treatments and will help to understand the behavior of the surviving cancer cells after treatment and shed light on studies of cancer resistance and recurrence. - Highlights: • Little is known about the behavior of the glioma cells surviving to TMZ. • The short- and long-term response of six glioma cells lines to TMZ varies considerably. • These glioma cells lines recovered proliferation after therapeutic levels of TMZ. • The growth velocity of the surviving cells was different from the untreated cells. • The kinetic of regrowth was not predicted by any TMZ-triggered mechanism.« less

Application of Graphene Based Nanotechnology in Stem Cells Research.

PubMed

Hu, Shanshan; Zeng, Yongxiang; Yang, Shuying; Qin, Han; Cai, He; Wang, Jian

2015-09-01

The past several years have witnessed significant advances in stem cell therapy, tissue engineering and regenerative medicine. Graphene, with its unique properties such as high electrical conductivity, elasticity and good molecule absorption, have potential for creating the next generation of biomaterials. This review summarizes the interrelationship between graphene and stem cells. The analysis of graphene when applied on mesenchymal stem cells, neural stem cells, induced pluripotent stem cells, embryonic stem cells, periodontal ligament stem cells, human adipose-derived stem cells and cancer stem cells, and how graphene influences cell behavior and differentiation are discussed in details.

Cell tracking for cell image analysis

NASA Astrophysics Data System (ADS)

Bise, Ryoma; Sato, Yoichi

2017-04-01

Cell image analysis is important for research and discovery in biology and medicine. In this paper, we present our cell tracking methods, which is capable of obtaining fine-grain cell behavior metrics. In order to address difficulties under dense culture conditions, where cell detection cannot be done reliably since cell often touch with blurry intercellular boundaries, we proposed two methods which are global data association and jointly solving cell detection and association. We also show the effectiveness of the proposed methods by applying the method to the biological researches.

Living Toroids - Cells on Toroidal Surfaces

NASA Astrophysics Data System (ADS)

Chang, Ya-Wen; Angelini, Thomas; Marquez, Samantha; Kim, Harold; Fernandez-Nieves, Alberto

2014-03-01

Cellular environment influences a multitude of cellular functions by providing chemical and physical signals that modulate cell behavior, dynamics, development, and eventually survival. Substrate mechanics has been recognized as one of the important physical cues that governs cell behavior at single cell level as well as in collective cell motion. Past research has suggested several contact-guided behaviors to be the result of surface curvature. However, studies on the effect of curvature are relatively scarce likely due to the difficulty in generating substrates with well-defined curvature. Here we describe the generation of toroidal droplets, which unlike spherical droplets, have regions of both positive and negative Gaussian curvature. Additionally, the range of curvatures can be controlled by varying the size and aspect ratio of the torus. Cells are either encapsulated inside toroidal droplets or located on toroidal hydrogel surfaces. Preliminary studies use B. Subtilis to study the organization of bacteria biofilms. When confined in droplets surrounded by yield-stress fluid, bacteria self-organize into heterogeneous biofilm at fluid- substrate interface. It is found that the surface curvature in the sub-millimeter scale has little effect on biofilm architecture.

Behavior of osteoblast-like cells on calcium-deficient hydroxyapatite ceramics composed of particles with different shapes and sizes.

PubMed

Kamitakahara, Masanobu; Uno, Yuika; Ioku, Koji

2014-01-01

In designing the biomaterials, it is important to control their surface morphologies, because they affect the interactions between the materials and cells. We previously reported that porous calcium-deficient hydroxyapatite (HA) ceramics composed of rod-like particles had advantages over sintered porous HA ceramics; however, the effects of the surface morphology of calcium-deficient HA ceramics on cell behavior have remained unclear. Using a hydrothermal process, we successfully prepared porous calcium-deficient HA ceramics with different surface morphologies, composed of plate-like particles of 200-300, 500-800 nm, or 2-3 μm in width and rod-like particles of 1 or 3-5 μm in width, respectively. The effects of these surface morphologies on the behavior of osteoblast-like cells were examined. Although the numbers of cells adhered to the ceramic specimens did not differ significantly among the specimens, the proliferation rates of cells on the ceramics decreased with decreasing particle size. Our results reveal that controlling the surface morphology that is governed by particle shape and size is important for designing porous calcium-deficient HA ceramics.

Cancer cells copy migratory behavior and exchange signaling networks via extracellular vesicles.

PubMed

Steenbeek, Sander C; Pham, Thang V; de Ligt, Joep; Zomer, Anoek; Knol, Jaco C; Piersma, Sander R; Schelfhorst, Tim; Huisjes, Rick; Schiffelers, Raymond M; Cuppen, Edwin; Jimenez, Connie R; van Rheenen, Jacco

2018-06-14

Recent data showed that cancer cells from different tumor subtypes with distinct metastatic potential influence each other's metastatic behavior by exchanging biomolecules through extracellular vesicles (EVs). However, it is debated how small amounts of cargo can mediate this effect, especially in tumors where all cells are from one subtype, and only subtle molecular differences drive metastatic heterogeneity. To study this, we have characterized the content of EVs shed in vivo by two clones of melanoma (B16) tumors with distinct metastatic potential. Using the Cre-LoxP system and intravital microscopy, we show that cells from these distinct clones phenocopy their migratory behavior through EV exchange. By tandem mass spectrometry and RNA sequencing, we show that EVs shed by these clones into the tumor microenvironment contain thousands of different proteins and RNAs, and many of these biomolecules are from interconnected signaling networks involved in cellular processes such as migration. Thus, EVs contain numerous proteins and RNAs and act on recipient cells by invoking a multi-faceted biological response including cell migration. © 2018 The Authors. Published under the terms of the CC BY 4.0 license.

Touching force response of the piezoelectric Braille cell.

PubMed

Smithmaitrie, Pruittikorn; Kanjantoe, Jinda; Tandayya, Pichaya

2008-11-01

The objective of this research is to investigate dynamic responses of the piezoelectric Braille cell when it is subjected to both electrical signal and touching force. Physical behavior of the piezoelectric actuator inside the piezoelectric Braille cell is analyzed. The mathematical model of the piezoelectric Braille system is presented. Then, data of visually impaired people using a Braille Note is studied as design information and a reference input for calculation of the piezoelectric Braille response under the touching force. The results show dynamic responses of the piezoelectric Braille cell. The designed piezoelectric bimorph has a settling time of 0.15 second. The relationship between the Braille dot height and applied voltage is linear. The behavior of the piezoelectric Braille dot when it is touched during operation shows that the dot height is decreased as the force increases. The result provides understanding of the piezoelectric Braille cell behavior under both touching force and electrical excitation simultaneously. This is the important issue for the design and development of piezoelectric Braille cells in senses of controlling Braille dot displacement or force-feedback in the future.

Sleep and Movement Differentiates Actions of Two Types of Somatostatin-Expressing GABAergic Interneuron in Rat Hippocampus

PubMed Central

Katona, Linda; Lapray, Damien; Viney, Tim J.; Oulhaj, Abderrahim; Borhegyi, Zsolt; Micklem, Benjamin R.; Klausberger, Thomas; Somogyi, Peter

2014-01-01

Summary Neuropeptides acting on pre- and postsynaptic receptors are coreleased with GABA by interneurons including bistratified and O-LM cells, both expressing somatostatin but innervating segregated dendritic domains of pyramidal cells. Neuropeptide release requires high-frequency action potentials, but the firing patterns of most peptide/GABA-releasing interneurons during behavior are unknown. We show that behavioral and network states differentiate the activities of bistratified and O-LM cells in freely moving rats. Bistratified cells fire at higher rates during sleep than O-LM cells and, unlike O-LM cells, strongly increase spiking during sharp wave-associated ripples (SWRs). In contrast, O-LM interneurons decrease firing during sleep relative to awake states and are mostly inhibited during SWRs. During movement, both cell types fire cooperatively at the troughs of theta oscillations but with different frequencies. Somatostatin and GABA are differentially released to distinct dendritic zones of CA1 pyramidal cells during sleep and wakefulness to coordinate segregated glutamatergic inputs from entorhinal cortex and CA3. PMID:24794095

Mosquito Protein Kinase G Phosphorylates Flavivirus NS5 and Alters Flight Behavior in Aedes aegypti and Anopheles gambiae

PubMed Central

Keating, Julie A.; Bhattacharya, Dipankar; Rund, Samuel S.C.; Hoover, Spencer; Dasgupta, Ranjit; Lee, Samuel J.; Duffield, Giles E.

2013-01-01

Abstract Many arboviral proteins are phosphorylated in infected mammalian cells, but it is unknown if the same phosphorylation events occur when insects are similarly infected. One of the mammalian kinases responsible for phosphorylation, protein kinase G (PKG), has been implicated in the behavior of multiple nonvector insects, but is unstudied in mosquitoes. PKG from Aedes aegypti was cloned, and phosphorylation of specific viral sites was monitored by mass spectrometry from biochemical and cell culture experiments. PKG from Aedes mosquitoes is able to phosphorylate dengue nonstructural protein 5 (NS5) at specific sites in cell culture and cell-free systems and autophosphorylates its own regulatory domain in a cell-free system. Injecting Aedes aegypti and Anopheles gambiae mosquitoes with a pharmacological PKG activator resulted in increased Aedes wing activity during periods of their natural diurnal/crepuscular activity and increased Anopheles nocturnal locomotor/flight activity. Thus, perturbation of the PKG signaling pathway in mosquitoes alters flight behavior. The demonstrated effect of PKG alterations is consistent with a viral PKG substrate triggering increased PKG activity. This increased PKG activity could be the mechanism by which dengue virus increases flight behavior and possibly facilitates transmission. Whether or not PKG is part of the mechanism by which dengue increases flight behavior, this report is the first to show PKG can modulate behavior in hematophagous disease vectors. PMID:23930976

Influence of long-term social interaction on chirping behavior, steroid levels and neurogenesis in weakly electric fish.

PubMed

Dunlap, Kent D; Chung, Michael; Castellano, James F

2013-07-01

Social interactions dramatically affect the brain and behavior of animals. Studies in birds and mammals indicate that socially induced changes in adult neurogenesis participate in the regulation of social behavior, but little is known about this relationship in fish. Here, we review studies in electric fish (Apteronotus leptorhychus) that link social stimulation, changes in electrocommunication behavior and adult neurogenesis in brain regions associated with electrocommunication. Compared with isolated fish, fish living in pairs have greater production of chirps, an electrocommunication signal, during dyadic interactions and in response to standardized artificial social stimuli. Social interaction also promotes neurogenesis in the periventricular zone, which contributes born cells to the prepacemaker nucleus, the brain region that regulates chirping. Both long-term chirp rate and periventricular cell addition depend on the signal dynamics (amplitude and waveform variation), modulations (chirps) and novelty of the stimuli from the partner fish. Socially elevated cortisol levels and cortisol binding to glucocorticoid receptors mediate, at least in part, the effect of social interaction on chirping behavior and brain cell addition. In a closely related electric fish (Brachyhypopomus gauderio), social interaction enhances cell proliferation specifically in brain regions for electrocommunication and only during the breeding season, when social signaling is most elaborate. Together, these studies demonstrate a consistent correlation between brain cell addition and environmentally regulated chirping behavior across many social and steroidal treatments and suggest a causal relationship.

Hazardous behavior of lithium batteries. Case histories

NASA Technical Reports Server (NTRS)

Marincic, N.

1983-01-01

Case histories were described of hazardous behavior for three different cell sizes ranging in nominal capacity from 300 mAh to 12,000 Ah. Design characteristics and other facts believed to have been responsible for the cell explosions, are presented. Obvious facts are discussed as causes for hazardous behavior of lithium batteries in general and oxyhalide batteries in particular.

Social Behavior in Medulloblastoma: Functional Analysis of Tumor-Supporting Glial Cells

DTIC Science & Technology

2012-07-01

AD_________________ Award Number: W81XWH-11-1-0557 TITLE: Social behavior in medulloblastoma ...1 July 2011 – 30 June 2012 4. TITLE AND SUBTITLE Social behavior in medulloblastoma : functional analysis of tumor-supporting glial cells 5a...Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Medulloblastoma is the most common malignant pediatric brain tumor. Granule neuron precursors

Role of Child and Maternal Processes in the Psychological Adjustment of Children with Sickle Cell Disease.

ERIC Educational Resources Information Center

Thompson, Robert J., Jr.; And Others

1993-01-01

Found that 64% of 50 children aged 7-12 years with sickle cell disease had parent-reported behavior problem. Internalizing types of behavior problems and diagnoses were most frequent. Maternal anxiety accounted for 16-33% of variance in mother-reported internalizing and externalizing behavior problems, respectively, and child pain-coping…

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

NASA Astrophysics Data System (ADS)

Smoak, Mollie; Hogan, Katie; Kriegh, Lisa; Chen, Cong; Terrell, LeKeith B.; Qureshi, Ammar T.; Todd Monroe, W.; Gimble, Jeffrey M.; Hayes, Daniel J.

2015-04-01

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

Engulfment of ceramic particles by fibroblasts does not alter cell behavior.

PubMed

Faye, Pierre-Antoine; Roualdes, Olivier; Rossignol, Fabrice; Hartmann, Daniel Jean; Desmoulière, Alexis

2017-02-17

Despite many studies, the impact of ceramic particles on cell behavior remains unclear. The aim of the present study was to investigate the effects of nano-sized ceramic particles on fibroblastic cells. Fibroblasts (dermal fibroblasts freshly isolated from skin samples and WI26 fibroblastic cells) were cultured in a monolayer in the presence of alumina or cerium-zirconia particles (≈50 nm diameter) at two concentrations (100 or 500 μg ml -1 ). Fluorescent alumina particles were also used. The following properties were analyzed: cell morphology, cytoplasmic ceramic incorporation (using confocal and transmission electron microscopy) and migration (using a silicon insert). Sedimentation field-flow fractionation (SdFFF) was also used to evaluate the rate of incorporation of ceramic particles into the cells. Finally, after treatment with various concentrations of ceramic particles, fibroblasts were also included in a collagen type I lattice constituting a dermal equivalent (DE), and the collagen lattice retraction and cell proliferation were evaluated. In monolayer conditions, the presence of both alumina and cerium-zirconia ceramic particles did not cause any deleterious effects on cultured cells (dermal fibroblast and WI26 cells) and cell fate was not affected in any way by the presence of ceramic particles in the cytoplasm. Confocal (using fluorescent alumina particles) and electron microscopy (using both alumina and cerium-zirconia particles) showed that ceramic particles were internalized in the WI26 cells. Using fluorescent membrane labeling and fluorescent alumina particles, a membrane was observed around the particle-containing vesicles present in the cytoplasm. Electron microscopy on WI26 cells showed the presence of a classical bilayer membrane around the ceramic particles. Interestingly, SdFFF confirmed that some dermal fibroblasts contained many alumina ceramic particles while others contained very few; in WI26 cells, the uptake of alumina ceramic was more homogeneous. In DE, collagen lattice retraction and cell proliferation were unchanged when WI26 fibroblastic cells contained alumina or cerium-zirconia ceramic particles. Our data suggest that ceramic particles are internalized in the cells by endocytosis. The presence of ceramic particles in the cytoplasm has no affect on cell behavior, confirming the excellent biocompatibility of this material and anticipating a minimal harmful effect of potential wear debris.

Coupling of Mechanical Behavior of Lithium Ion Cells to Electrochemical-Thermal (ECT) Models for Battery Crush

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

Zhang, Chao; Santhanagopalan, Shriram; Pesaran, Ahmad

Vehicle crashes can lead to crushing of the battery, damaging lithium ion battery cells and causing local shorts, heat generation, and thermal runaway. Simulating all the physics and geometries at the same time is challenging and takes a lot of effort; thus, simplifications are needed. We developed a material model for simultaneously modeling the mechanical-electrochemical-thermal behavior, which predicted the electrical short, voltage drop, and thermal runaway behaviors followed by a mechanical abuse-induced short. The effect of short resistance on the battery cell performance was studied.

Contact behavior modelling and its size effect on proton exchange membrane fuel cell

NASA Astrophysics Data System (ADS)

Qiu, Diankai; Peng, Linfa; Yi, Peiyun; Lai, Xinmin; Janßen, Holger; Lehnert, Werner

2017-10-01

Contact behavior between the gas diffusion layer (GDL) and bipolar plate (BPP) is of significant importance for proton exchange membrane fuel cells. Most current studies on contact behavior utilize experiments and finite element modelling and focus on fuel cells with graphite BPPs, which lead to high costs and huge computational requirements. The objective of this work is to build a more effective analytical method for contact behavior in fuel cells and investigate the size effect resulting from configuration alteration of channel and rib (channel/rib). Firstly, a mathematical description of channel/rib geometry is outlined in accordance with the fabrication of metallic BPP. Based on the interface deformation characteristic and Winkler surface model, contact pressure between BPP and GDL is then calculated to predict contact resistance and GDL porosity as evaluative parameters of contact behavior. Then, experiments on BPP fabrication and contact resistance measurement are conducted to validate the model. The measured results demonstrate an obvious dependence on channel/rib size. Feasibility of the model used in graphite fuel cells is also discussed. Finally, size factor is proposed for evaluating the rule of size effect. Significant increase occurs in contact resistance and porosity for higher size factor, in which channel/rib width decrease.

The behavior of MC3T3-E1 cells on chitosan/poly-L-lysine composite films: effect of nanotopography, surface chemistry, and wettability.

PubMed

Zheng, Zhenhuan; Zhang, Ling; Kong, Lijun; Wang, Aijun; Gong, Yandao; Zhang, Xiufang

2009-05-01

In the present work, a series of composite films were produced from chitosan/poly-L-lysine blend solutions. The surface topography, chemistry, and wettability of composite films were characterized by atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and contact angle assay, respectively. For all composite films, blending with poly-L-lysine induced changes in surface chemistry and wettability. Interestingly, it was also found that increasing poly-L-lysine weight fraction in blend solutions could result in different nanoscaled surface topographic features, which displayed particle-, granule-, or fiber-dominant morphologies. MC3T3-E1 osteoblast-like cells were cultured on all composite films to evaluate the effects of surface nanotopography, chemistry, and wettability on cell behavior. The observations indicated that MC3T3-E1 cell behavior was affected by surface topography, chemistry, and wettability simultaneously and that cells showed strong responses to surface topography. On fiber-dominant surface, cells fully spread with obvious cytoskeleton organization and exhibited significantly higher level of adhesion and proliferation compared with particle- or granule-dominant surfaces. Furthermore, fiber-dominant surface also induced greater expression of mature osteogenic marker osteocalcin and higher mineralization based on RT-PCR and von Kossa staining. The results suggest that topographic modification of chitosan substratum at the nanoscale may be exploited in regulating cell behavior for its applications in tissue engineering.

Differentiated cell behavior: a multiscale approach using measure theory.

PubMed

Colombi, Annachiara; Scianna, Marco; Tosin, Andrea

2015-11-01

This paper deals with the derivation of a collective model of cell populations out of an individual-based description of the underlying physical particle system. By looking at the spatial distribution of cells in terms of time-evolving measures, rather than at individual cell paths, we obtain an ensemble representation stemming from the phenomenological behavior of the single component cells. In particular, as a key advantage of our approach, the scale of representation of the system, i.e., microscopic/discrete vs. macroscopic/continuous, can be chosen a posteriori according only to the spatial structure given to the aforesaid measures. The paper focuses in particular on the use of different scales based on the specific functions performed by cells. A two-population hybrid system is considered, where cells with a specialized/differentiated phenotype are treated as a discrete population of point masses while unspecialized/undifferentiated cell aggregates are represented by a continuous approximation. Numerical simulations and analytical investigations emphasize the role of some biologically relevant parameters in determining the specific evolution of such a hybrid cell system.

Optical regulation of protein adsorption and cell adhesion by photoresponsive GaN nanowires.

PubMed

Li, Jingying; Han, Qiusen; Zhang, Ying; Zhang, Wei; Dong, Mingdong; Besenbacher, Flemming; Yang, Rong; Wang, Chen

2013-10-09

Interfacing nanowires with living cells is attracting more and more interest due to the potential applications, such as cell culture engineering and drug delivery. We report on the feasibility of using photoresponsive semiconductor gallium nitride (GaN) nanowires (NWs) for regulating the behaviors of biomolecules and cells at the nano/biointerface. The GaN NWs have been fabricated by a facile chemical vapor deposition method. The superhydrophobicity to superhydrophilicity transition of the NWs is achieved by UV illumination. Bovine serum albumin adsorption could be modulated by photoresponsive GaN NWs. Tunable cell detachment and adhesion are also observed. The mechanism of the NW surface responsible for modulating both of protein adsorption and cell adhesion is discussed. These observations of the modulation effects on protein adsorption and cell adhesion by GaN NWs could provide a novel approach toward the regulation of the behaviors of biomolecules and cells at the nano/biointerface, which may be of considerable importance in the development of high-performance semiconductor nanowire-based biomedical devices for cell culture engineering, bioseparation, and diagnostics.

Studies of intercellular invasion in vitro using rabbit peritoneal neutrophil granulocytes (PMNS). I. Role of contact inhibition of locomotion

PubMed Central

1975-01-01

Intercellular invasion is the active migration of cells on one type into the interiors of tissues composed of cells of dissimilar cell types. Contact paralysis of locomotion is the cessation of forward extension of the pseudopods of a cell as a result of its collision with another cell. One hypothesis to account for intercellular invasion proposes that a necessary condition for a cell type to be invasive to a given host tissue is that it lack contact paralysis of locomotion during collision with cells of that host tissue. The hypothesis has been tested using rabbit peritoneal neutrophil granulocytes (PMNs) as the invasive cell type and chick embryo fibroblasts as the host tissue. In organ culture, PMNs rapidly invade aggregates of fibroblasts. The behavior of the pseudopods of PMNs during collision with fibroblasts was analyzed for contact paralysis by a study of time-lapse films of cells in mixed monolayer culture. In monolayer culture, PMNs show little sign of paralysis of the pseudopods upon collision with fibroblasts and thus conform in their behavior to that predicted by the hypothesis. PMID:1092702

Characterization of the Cell Surface Properties of Drinking Water Pathogens by Microbial Adhesion to Hydrocarbon and Electrophoretic Mobility Measurements

EPA Science Inventory

The surface characteristics of microbial cells directly influence their mobility and behavior within aqueous environments. The cell surface hydrophobicity (CSH) and electrophoretic mobility (EPM) of microbial cells impact a number of interactions and processes including aggregati...

Cell Migration in Tissues: Explant Culture and Live Imaging.

PubMed

Staneva, Ralitza; Barbazan, Jorge; Simon, Anthony; Vignjevic, Danijela Matic; Krndija, Denis

2018-01-01

Cell migration is a process that ensures correct cell localization and function in development and homeostasis. In disease such as cancer, cells acquire an upregulated migratory capacity that leads to their dissemination throughout the body. Live imaging of cell migration allows for better understanding of cell behaviors in development, adult tissue homeostasis and disease. We have optimized live imaging procedures to track cell migration in adult murine tissue explants derived from: (1) healthy gut; (2) primary intestinal carcinoma; and (3) the liver, a common metastatic site. To track epithelial cell migration in the gut, we generated an inducible fluorescent reporter mouse, enabling us to visualize and track individual cells in unperturbed gut epithelium. To image intratumoral cancer cells, we use a spontaneous intestinal cancer model based on the activation of Notch1 and deletion of p53 in the mouse intestinal epithelium, which gives rise to aggressive carcinoma. Interaction of cancer cells with a metastatic niche, the mouse liver, is addressed using a liver colonization model. In summary, we describe a method for long-term 3D imaging of tissue explants by two-photon excitation microscopy. Explant culturing and imaging can help understand dynamic behavior of cells in homeostasis and disease, and would be applicable to various tissues.

Quantitative Analysis of Cell Migration Using Optical Flow

PubMed Central

Boric, Katica; Orio, Patricio; Viéville, Thierry; Whitlock, Kathleen

2013-01-01

Neural crest cells exhibit dramatic migration behaviors as they populate their distant targets. Using a line of zebrafish expressing green fluorescent protein (sox10:EGFP) in neural crest cells we developed an assay to analyze and quantify cell migration as a population, and use it here to characterize in detail the subtle defects in cell migration caused by ethanol exposure during early development. The challenge was to quantify changes in the in vivo migration of all Sox10:EGFP expressing cells in the visual field of time-lapse movies. To perform this analysis we used an Optical Flow algorithm for motion detection and combined the analysis with a fit to an affine transformation. Through this analysis we detected and quantified significant differences in the cell migrations of Sox10:EGFP positive cranial neural crest populations in ethanol treated versus untreated embryos. Specifically, treatment affected migration by increasing the left-right asymmetry of the migrating cells and by altering the direction of cell movements. Thus, by applying this novel computational analysis, we were able to quantify the movements of populations of cells, allowing us to detect subtle changes in cell behaviors. Because cranial neural crest cells contribute to the formation of the frontal mass these subtle differences may underlie commonly observed facial asymmetries in normal human populations. PMID:23936049

Reprogramming primordial germ cells (PGC) to embryonic germ (EG) cells.

PubMed

Durcova-Hills, Gabriela; Surani, Azim

2008-04-01

In this unit we describe the derivation of pluripotent embryonic germ (EG) cells from mouse primordial germ cells (PGCs) isolated from both 8.5- and 11.5-days post-coitum (dpc) embryos. Once EG cells are derived we explain how to propagate and characterize the cell lines. We introduce readers to PGCs and explain differences between PGCs and their in vitro derivatives EG cells. Finally, we also compare mouse EG cells with ES cells. This unit will be of great interest to anyone interested in PGCs or studying the behavior of cultured PGCs or the derivation of new EG cell lines.

Maintaining the pluripotency of mouse embryonic stem cells on gold nanoparticle layers with nanoscale but not microscale surface roughness.

PubMed

Lyu, Zhonglin; Wang, Hongwei; Wang, Yanyun; Ding, Kaiguo; Liu, Huan; Yuan, Lin; Shi, Xiujuan; Wang, Mengmeng; Wang, Yanwei; Chen, Hong

2014-06-21

Efficient control of the self-renewal and pluripotency maintenance of embryonic stem cell (ESC) is a prerequisite for translating stem cell technologies to clinical applications. Surface topography is one of the most important factors that regulates cell behaviors. In the present study, micro/nano topographical structures composed of a gold nanoparticle layer (GNPL) with nano-, sub-micro-, and microscale surface roughnesses were used to study the roles of these structures in regulating the behaviors of mouse ESCs (mESCs) under feeder-free conditions. The distinctive results from Oct-4 immunofluorescence staining and quantitative real-time polymerase chain reaction (qPCR) demonstrate that nanoscale and low sub-microscale surface roughnesses (Rq less than 392 nm) are conducive to the long-term maintenance of mESC pluripotency, while high sub-microscale and microscale surface roughnesses (Rq greater than 573 nm) result in a significant loss of mESC pluripotency and a faster undirectional differentiation, particularly in long-term culture. Moreover, the likely signalling cascades engaged in the topological sensing of mESCs were investigated and their role in affecting the maintenance of the long-term cell pluripotency was discussed by analyzing the expression of proteins related to E-cadherin mediated cell-cell adhesions and integrin-mediated focal adhesions (FAs). Additionally, the conclusions from MTT, cell morphology staining and alkaline phosphatase (ALP) activity assays show that the surface roughness can provide a potent regulatory signal for various mESC behaviors, including cell attachment, proliferation and osteoinduction.

Cell rejuvenation and social behaviors promoted by LPS exchange in myxobacteria.

PubMed

Vassallo, Christopher; Pathak, Darshankumar T; Cao, Pengbo; Zuckerman, David M; Hoiczyk, Egbert; Wall, Daniel

2015-06-02

Bacterial cells in their native environments must cope with factors that compromise the integrity of the cell. The mechanisms of coping with damage in a social or multicellular context are poorly understood. Here we investigated how a model social bacterium, Myxococcus xanthus, approaches this problem. We focused on the social behavior of outer membrane exchange (OME), in which cells transiently fuse and exchange their outer membrane (OM) contents. This behavior requires TraA, a homophilic cell surface receptor that identifies kin based on similarities in a polymorphic region, and the TraB cohort protein. As observed by electron microscopy, TraAB overexpression catalyzed a prefusion OM junction between cells. We then showed that damage sustained by the OM of one population was repaired by OME with a healthy population. Specifically, LPS mutants that were defective in motility and sporulation were rescued by OME with healthy donors. In addition, a mutant with a conditional lethal mutation in lpxC, an essential gene required for lipid A biosynthesis, was rescued by Tra-dependent interactions with a healthy population. Furthermore, lpxC cells with damaged OMs, which were more susceptible to antibiotics, had resistance conferred to them by OME with healthy donors. We also show that OME has beneficial fitness consequences to all cells. Here, in merged populations of damaged and healthy cells, OME catalyzed a dilution of OM damage, increasing developmental sporulation outcomes of the combined population by allowing it to reach a threshold density. We propose that OME is a mechanism that myxobacteria use to overcome cell damage and to transition to a multicellular organism.

Oral pathogens change proliferation properties of oral tumor cells by affecting gene expression of human defensins.

PubMed

Hoppe, T; Kraus, D; Novak, N; Probstmeier, R; Frentzen, M; Wenghoefer, M; Jepsen, S; Winter, J

2016-10-01

The impact of oral pathogens onto the generation and variability of oral tumors has only recently been investigated. To get further insights, oral cancer cells were treated with pathogens and additionally, as a result of this bacterial cellular infection, with human defensins, which are as anti-microbial peptide members of the innate immune system. After cell stimulation, proliferation behavior, expression analysis of oncogenic relevant defensin genes, and effects on EGFR signaling were investigated. The expression of oncogenic relevant anti-microbial peptides was analyzed with real-time PCR and immunohistochemistry. Cell culture experiments were performed to examine cellular impacts caused by stimulation, i.e., altered gene expression, proliferation rate, and EGF receptor-dependent signaling. Incubation of oral tumor cells with an oral pathogen (Porphyromonas gingivalis) and human α-defensins led to an increase in cell proliferation. In contrast, another oral bacterium used, Aggregatibacter actinomycetemcomitans, enhanced cell death. The bacteria and anti-microbial peptides exhibited diverse effects on the transcript levels of oncogenic relevant defensin genes and epidermal growth factor receptor signaling. These two oral pathogens exhibited opposite primary effects on the proliferation behavior of oral tumor cells. Nevertheless, both microbe species led to similar secondary impacts on the proliferation rate by modifying expression levels of oncogenic relevant α-defensin genes. In this respect, oral pathogens exerted multiplying effects on tumor cell proliferation. Additionally, human defensins were shown to differently influence epidermal growth factor receptor signaling, supporting the hypothesis that these anti-microbial peptides serve as ligands of EGFR, thus modifying the proliferation behavior of oral tumor cells.

Multidimensional Single-Cell Analysis of BCR Signaling Reveals Proximal Activation Defect As a Hallmark of Chronic Lymphocytic Leukemia B Cells

PubMed Central

Palomba, M. Lia; Piersanti, Kelly; Ziegler, Carly G. K.; Decker, Hugo; Cotari, Jesse W.; Bantilan, Kurt; Rijo, Ivelise; Gardner, Jeff R.; Heaney, Mark; Bemis, Debra; Balderas, Robert; Malek, Sami N.; Seymour, Erlene; Zelenetz, Andrew D.

2014-01-01

Purpose Chronic Lymphocytic Leukemia (CLL) is defined by a perturbed B-cell receptor-mediated signaling machinery. We aimed to model differential signaling behavior between B cells from CLL and healthy individuals to pinpoint modes of dysregulation. Experimental Design We developed an experimental methodology combining immunophenotyping, multiplexed phosphospecific flow cytometry, and multifactorial statistical modeling. Utilizing patterns of signaling network covariance, we modeled BCR signaling in 67 CLL patients using Partial Least Squares Regression (PLSR). Results from multidimensional modeling were validated using an independent test cohort of 38 patients. Results We identified a dynamic and variable imbalance between proximal (pSYK, pBTK) and distal (pPLCγ2, pBLNK, ppERK) phosphoresponses. PLSR identified the relationship between upstream tyrosine kinase SYK and its target, PLCγ2, as maximally predictive and sufficient to distinguish CLL from healthy samples, pointing to this juncture in the signaling pathway as a hallmark of CLL B cells. Specific BCR pathway signaling signatures that correlate with the disease and its degree of aggressiveness were identified. Heterogeneity in the PLSR response variable within the B cell population is both a characteristic mark of healthy samples and predictive of disease aggressiveness. Conclusion Single-cell multidimensional analysis of BCR signaling permitted focused analysis of the variability and heterogeneity of signaling behavior from patient-to-patient, and from cell-to-cell. Disruption of the pSYK/pPLCγ2 relationship is uncovered as a robust hallmark of CLL B cell signaling behavior. Together, these observations implicate novel elements of the BCR signal transduction as potential therapeutic targets. PMID:24489640

Teen Drivers’ Perceptions of Inattention and Cell Phone Use While Driving

PubMed Central

Sommers, Marilyn S.

2015-01-01

Objective Inattention to the roadway, including cell phone use while driving (cell phone calls, sending and reading texts, mobile app use and internet use), is a critical problem for teen drivers and increases risk for crashes. Effective behavioral interventions for teens are needed in order to decrease teen driver inattention related to cell phone use while driving. However, teens’ perceptions of mobile device use while driving is a necessary component for theoretically driven behavior change interventions. The purpose of this study was to describe teen drivers’ perceptions of cell phone use while driving in order to inform future interventions to reduce risky driving. Methods We conducted seven focus groups with a total of 30 teen drivers, ages 16–18, licensed for ≤1 year in Pennsylvania. The focus group interview guide and analysis were based on the Theory of Planned Behavior, identifying the attitudes, perceived behavioral control, and norms about inattention to the roadway. Directed descriptive content analysis was used to analyze the focus group interviews. All focus groups were coded by two research team members and discrepancies were reconciled. Themes were developed based on the data. Results Teens had a mean age of 17.39 (sd 0.52), mean length of licensure of 173.7 days (sd 109.2; range 4–364), were 50% male and predominately white (90%) and non-Hispanic (97%). From the focus group data, three major themes emerged; (1) Recognizing the danger but still engaging; (2) Considering context; and (3) Formulating safer behaviors that might reduce risk. In spite of recognizing hand-held cell phone use, texting and social media app use are dangerous and distracting while driving, teens and their peers often engage in these behaviors. Teens described how the context of the situation contributed to whether a teen would place or answer a call, write or respond to a text, or use a social media app. Teens identified ways in which they controlled their behaviors, although some still drew attention away from the roadway. Conclusions Cell phone use while driving is a contributor to motor vehicle crashes in teens and effective interventions to decrease risks are needed. Teens viewed some types of cell phone use as unsafe and describe methods in which they control their behaviors. However, some of their methods still take attention off the primary task of driving. Teens could benefit from behavior change interventions that propose strategies to promote focused attention on the roadway at all times during the driving trip. PMID:26436243

Teen Drivers' Perceptions of Inattention and Cell Phone Use While Driving.

PubMed

McDonald, Catherine C; Sommers, Marilyn S

2015-01-01

Inattention to the roadway, including cell phone use while driving (cell phone calls, sending and reading texts, mobile app use, and Internet use), is a critical problem for teen drivers and increases risk for crashes. Effective behavioral interventions for teens are needed in order to decrease teen driver inattention related to cell phone use while driving. However, teens' perceptions of mobile device use while driving is a necessary component for theoretically driven behavior change interventions. The purpose of this study was to describe teen drivers' perceptions of cell phone use while driving in order to inform future interventions to reduce risky driving. We conducted 7 focus groups with a total of 30 teen drivers, ages 16-18, licensed for ≤ 1 year in Pennsylvania. The focus group interview guide and analysis were based on the Theory of Planned Behavior, identifying the attitudes, perceived behavioral control, and norms about inattention to the roadway. Directed descriptive content analysis was used to analyze the focus group interviews. All focus groups were coded by 2 research team members and discrepancies were reconciled. Themes were developed based on the data. Teens had a mean age of 17.39 (SD = 0.52), mean length of licensure of 173.7 days (SD = 109.2; range 4-364), were 50% male and predominately white (90%) and non-Hispanic (97%). From the focus group data, 3 major themes emerged: (1) Recognizing the danger but still engaging; (2) Considering context; and (3) Formulating safer behaviors that might reduce risk. Despite recognizing that handheld cell phone use, texting, and social media app use are dangerous and distracting while driving, teens and their peers often engaged in these behaviors. Teens described how the context of the situation contributed to whether a teen would place or answer a call, write or respond to a text, or use a social media app. Teens identified ways in which they controlled their behaviors, although some still drew attention away from the roadway. Cell phone use while driving is a contributor to motor vehicle crashes in teens, and effective interventions to decrease risks are needed. Teens viewed some types of cell phone use as unsafe and describe methods in which they control their behaviors. However, some of their methods still take attention off the primary task of driving. Teens could benefit from behavior change interventions that propose strategies to promote focused attention on the roadway at all times during the driving trip.

Segregation of Visual Response Properties in the Mouse Superior Colliculus and Their Modulation during Locomotion

PubMed Central

2017-01-01

The superior colliculus (SC) receives direct input from the retina and integrates it with information about sound, touch, and state of the animal that is relayed from other parts of the brain to initiate specific behavioral outcomes. The superficial SC layers (sSC) contain cells that respond to visual stimuli, whereas the deep SC layers (dSC) contain cells that also respond to auditory and somatosensory stimuli. Here, we used a large-scale silicon probe recording system to examine the visual response properties of SC cells of head-fixed and alert male mice. We found cells with diverse response properties including: (1) orientation/direction-selective (OS/DS) cells with a firing rate that is suppressed by drifting sinusoidal gratings (negative OS/DS cells); (2) suppressed-by-contrast cells; (3) cells with complex-like spatial summation nonlinearity; and (4) cells with Y-like spatial summation nonlinearity. We also found specific response properties that are enriched in different depths of the SC. The sSC is enriched with cells with small RFs, high evoked firing rates (FRs), and sustained temporal responses, whereas the dSC is enriched with the negative OS/DS cells and with cells with large RFs, low evoked FRs, and transient temporal responses. Locomotion modulates the activity of the SC cells both additively and multiplicatively and changes the preferred spatial frequency of some SC cells. These results provide the first description of the negative OS/DS cells and demonstrate that the SC segregates cells with different response properties and that the behavioral state of a mouse affects SC activity. SIGNIFICANCE STATEMENT The superior colliculus (SC) receives visual input from the retina in its superficial layers (sSC) and induces eye/head-orientating movements and innate defensive responses in its deeper layers (dSC). Despite their importance, very little is known about the visual response properties of dSC neurons. Using high-density electrode recordings and novel model-based analysis, we found several novel visual response properties of the SC cells, including encoding of a cell's preferred orientation or direction by suppression of the firing rate. The sSC and the dSC are enriched with cells with different visual response properties. Locomotion modulates the cells in the SC. These findings contribute to our understanding of how the SC processes visual inputs, a critical step in comprehending visually guided behaviors. PMID:28760858

Changes in androgen receptor, estrogen receptor alpha, and sexual behavior with aging and testosterone in male rats.

PubMed

Wu, Di; Gore, Andrea C

2010-07-01

Reproductive aging in males is characterized by a diminution in sexual behavior beginning in middle age. We investigated the relationships among testosterone, androgen receptor (AR) and estrogen receptor alpha (ERalpha) cell numbers in the hypothalamus, and their relationship to sexual performance in male rats. Young (3months) and middle-aged (12months) rats were given sexual behavior tests, then castrated and implanted with vehicle or testosterone capsules. Rats were tested again for sexual behavior. Numbers of AR and ERalpha immunoreactive cells were counted in the anteroventral periventricular nucleus and the medial preoptic nucleus, and serum hormones were measured. Middle-aged intact rats had significant impairments of all sexual behavior measures compared to young males. After castration and testosterone implantation, sexual behaviors in middle-aged males were largely comparable to those in the young males. In the hypothalamus, AR cell density was significantly (5-fold) higher, and ERalpha cell density significantly (6-fold) lower, in testosterone- than vehicle-treated males, with no age differences. Thus, restoration of serum testosterone to comparable levels in young and middle-aged rats resulted in similar preoptic AR and ERalpha cell density concomitant with a reinstatement of most behaviors. These data suggest that age-related differences in sexual behavior cannot be due to absolute levels of testosterone, and further, the middle-aged brain retains the capacity to respond to exogenous testosterone with changes in hypothalamic AR and ERalpha expression. Our finding that testosterone replacement in aging males has profound effects on hypothalamic receptors and behavior has potential medical implications for the treatment of age-related hypogonadism in men. Copyright 2010 Elsevier Inc. All rights reserved.

Influence of nanostructural environment and fluid flow on osteoblast-like cell behavior: a model for cell-mechanics studies.

PubMed

Prodanov, L; Semeins, C M; van Loon, J J W A; te Riet, J; Jansen, J A; Klein-Nulend, J; Walboomers, X F

2013-05-01

Introducing nanoroughness on various biomaterials has been shown to profoundly effect cell-material interactions. Similarly, physical forces act on a diverse array of cells and tissues. Particularly in bone, the tissue experiences compressive or tensile forces resulting in fluid shear stress. The current study aimed to develop an experimental setup for bone cell behavior, combining a nanometrically grooved substrate (200 nm wide, 50 nm deep) mimicking the collagen fibrils of the extracellular matrix, with mechanical stimulation by pulsatile fluid flow (PFF). MC3T3-E1 osteoblast-like cells were assessed for morphology, expression of genes involved in cell attachment and osteoblastogenesis and nitric oxide (NO) release. The results showed that both nanotexture and PFF did affect cellular morphology. Cells aligned on nanotexture substrate in a direction parallel to the groove orientation. PFF at a magnitude of 0.7 Pa was sufficient to induce alignment of cells on a smooth surface in a direction perpendicular to the applied flow. When environmental cues texture and flow were interacting, PFF of 1.4 Pa applied parallel to the nanogrooves initiated significant cellular realignment. PFF increased NO synthesis 15-fold in cells attached to both smooth and nanotextured substrates. Increased collagen and alkaline phosphatase mRNA expression was observed on the nanotextured substrate, but not on the smooth substrate. Furthermore, vinculin and bone sialoprotein were up-regulated after 1 h of PFF stimulation. In conclusion, the data show that interstitial fluid forces and structural cues mimicking extracellular matrix contribute to the final bone cell morphology and behavior, which might have potential application in tissue engineering. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Ascites-induced shift along epithelial-mesenchymal spectrum in ovarian cancer cells: enhancement of their invasive behavior partly dependant on αv integrins.

PubMed

Carduner, L; Leroy-Dudal, J; Picot, C R; Gallet, O; Carreiras, F; Kellouche, S

2014-08-01

At least one-third of patients with epithelial ovarian cancer (OC) present ascites at diagnosis and almost all have ascites at recurrence. The presence of ascites, which acts as a dynamic reservoir of active molecules and cellular components, correlates with the OC peritoneal metastasis and is associated with poor prognosis. Since epithelial-mesenchymal transition (EMT) is involved in different phases of OC progression, we have investigated the effect of the unique ascitic tumor microenvironment on the EMT status and the behavior of OC cells. The exposure of three OC cell lines to ascites leads to changes in cellular morphologies. Within ascites, OC cells harboring an initial intermediate epithelial phenotype are characterized by marked dislocation of epithelial markers (E-cadherin, ZO-1 staining) while OC cells initially harboring an intermediate mesenchymal phenotype strengthen their mesenchymal markers (N-cadherin, vimentin). Ascites differentially triggers a dissemination phenotype related to the initial cell features by either allowing the proliferation and the formation of spheroids and the extension of colonies for cells that present an initial epithelial intermediate phenotype, or favoring the migration of cells with a mesenchymal intermediate phenotype. In an ascitic microenvironment, a redeployment of αv integrins into cells was observed and the ascites-induced accentuation of the two different invasive phenotypes (i.e. spheroids formation or migration) was shown to involve αv integrins. Thus, ascites induces a shift toward an unstable intermediate state of the epithelial-mesenchymal spectrum and confers a more aggressive cell behavior that takes on a different pathway based on the initial epithelial-mesenchymal cell features.

Modeling an Excitable Biosynthetic Tissue with Inherent Variability for Paired Computational-Experimental Studies.

PubMed

Gokhale, Tanmay A; Kim, Jong M; Kirkton, Robert D; Bursac, Nenad; Henriquez, Craig S

2017-01-01

To understand how excitable tissues give rise to arrhythmias, it is crucially necessary to understand the electrical dynamics of cells in the context of their environment. Multicellular monolayer cultures have proven useful for investigating arrhythmias and other conduction anomalies, and because of their relatively simple structure, these constructs lend themselves to paired computational studies that often help elucidate mechanisms of the observed behavior. However, tissue cultures of cardiomyocyte monolayers currently require the use of neonatal cells with ionic properties that change rapidly during development and have thus been poorly characterized and modeled to date. Recently, Kirkton and Bursac demonstrated the ability to create biosynthetic excitable tissues from genetically engineered and immortalized HEK293 cells with well-characterized electrical properties and the ability to propagate action potentials. In this study, we developed and validated a computational model of these excitable HEK293 cells (called "Ex293" cells) using existing electrophysiological data and a genetic search algorithm. In order to reproduce not only the mean but also the variability of experimental observations, we examined what sources of variation were required in the computational model. Random cell-to-cell and inter-monolayer variation in both ionic conductances and tissue conductivity was necessary to explain the experimentally observed variability in action potential shape and macroscopic conduction, and the spatial organization of cell-to-cell conductance variation was found to not impact macroscopic behavior; the resulting model accurately reproduces both normal and drug-modified conduction behavior. The development of a computational Ex293 cell and tissue model provides a novel framework to perform paired computational-experimental studies to study normal and abnormal conduction in multidimensional excitable tissue, and the methodology of modeling variation can be applied to models of any excitable cell.

A model of the regulatory network involved in the control of the cell cycle and cell differentiation in the Caenorhabditis elegans vulva.

PubMed

Weinstein, Nathan; Ortiz-Gutiérrez, Elizabeth; Muñoz, Stalin; Rosenblueth, David A; Álvarez-Buylla, Elena R; Mendoza, Luis

2015-03-13

There are recent experimental reports on the cross-regulation between molecules involved in the control of the cell cycle and the differentiation of the vulval precursor cells (VPCs) of Caenorhabditis elegans. Such discoveries provide novel clues on how the molecular mechanisms involved in the cell cycle and cell differentiation processes are coordinated during vulval development. Dynamic computational models are helpful to understand the integrated regulatory mechanisms affecting these cellular processes. Here we propose a simplified model of the regulatory network that includes sufficient molecules involved in the control of both the cell cycle and cell differentiation in the C. elegans vulva to recover their dynamic behavior. We first infer both the topology and the update rules of the cell cycle module from an expected time series. Next, we use a symbolic algorithmic approach to find which interactions must be included in the regulatory network. Finally, we use a continuous-time version of the update rules for the cell cycle module to validate the cyclic behavior of the network, as well as to rule out the presence of potential artifacts due to the synchronous updating of the discrete model. We analyze the dynamical behavior of the model for the wild type and several mutants, finding that most of the results are consistent with published experimental results. Our model shows that the regulation of Notch signaling by the cell cycle preserves the potential of the VPCs and the three vulval fates to differentiate and de-differentiate, allowing them to remain completely responsive to the concentration of LIN-3 and lateral signal in the extracellular microenvironment.

Neuron-like differentiation of mesenchymal stem cells on silicon nanowires

NASA Astrophysics Data System (ADS)

Kim, Hyunju; Kim, Ilsoo; Choi, Heon-Jin; Kim, So Yeon; Yang, Eun Gyeong

2015-10-01

The behavior of mammalian cells on vertical nanowire (NW) arrays, including cell spreading and the dynamic distribution of focal adhesions and cytoskeletal proteins, has been intensively studied to extend the implications for cellular manipulations in vitro. Prompted by the result that cells on silicon (Si) NWs showed morphological changes and reduced migration rates, we have explored the transition of mesenchymal stem cells into a neuronal lineage by using SiNWs with varying lengths. When human mesenchymal stem cells (hMSCs) were cultured on the longest SiNWs for 3 days, most of the cells exhibited elongated shapes with neurite-like extensions and dot-like focal adhesions that were prominently observed along with actin filaments. Under these circumstances, the cell motility analyzed by live cell imaging was found to decrease due to the presence of SiNWs. In addition, the slowed growth rate, as well as the reduced population of S phase cells, suggested that the cell cycle was likely arrested in response to the differentiation process. Furthermore, we measured the mRNA levels of several lineage-specific markers to confirm that the SiNWs actually induced neuron-like differentiation of the hMSCs while hampering their osteogenic differentiation. Taken together, our results implied that SiNWs were capable of inducing active reorganization of cellular behaviors, collectively guiding the fate of hMSCs into the neural lineage even in the absence of any inducing reagent.The behavior of mammalian cells on vertical nanowire (NW) arrays, including cell spreading and the dynamic distribution of focal adhesions and cytoskeletal proteins, has been intensively studied to extend the implications for cellular manipulations in vitro. Prompted by the result that cells on silicon (Si) NWs showed morphological changes and reduced migration rates, we have explored the transition of mesenchymal stem cells into a neuronal lineage by using SiNWs with varying lengths. When human mesenchymal stem cells (hMSCs) were cultured on the longest SiNWs for 3 days, most of the cells exhibited elongated shapes with neurite-like extensions and dot-like focal adhesions that were prominently observed along with actin filaments. Under these circumstances, the cell motility analyzed by live cell imaging was found to decrease due to the presence of SiNWs. In addition, the slowed growth rate, as well as the reduced population of S phase cells, suggested that the cell cycle was likely arrested in response to the differentiation process. Furthermore, we measured the mRNA levels of several lineage-specific markers to confirm that the SiNWs actually induced neuron-like differentiation of the hMSCs while hampering their osteogenic differentiation. Taken together, our results implied that SiNWs were capable of inducing active reorganization of cellular behaviors, collectively guiding the fate of hMSCs into the neural lineage even in the absence of any inducing reagent. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05787f

Effects of graphene quantum dots on linear and nonlinear optical behavior of malignant ovarian cells

NASA Astrophysics Data System (ADS)

Mohajer, Salman; Ara, Mohammad Hossein Majles; Serahatjoo, Leila

2016-07-01

We investigate linear and nonlinear optical properties of standard human ovarian cancer cells (cell line: A2780cp) in vitro. Cells were treated by graphene quantum dots (GQDs) with two special concentrations. Nontoxicity of GQDs was examined in standard biological viability tests. Cancerous cells were fixed on a glass slide; then, interaction of light with biofilms was studied in linear and nonlinear regimes. Absorption spectra of untreated biofilms and biofilms with two different concentrations of GQDs was studied by UV-visible spectrophotometer. Optical behavior of biofilms in a linear regime of intensity (with low-intensity laser exposure) was reported using a simple optical setup. After that, we compared the attenuation of light in biofilm of cancerous cells with and without GQDs. Nonlinear behavior of these biofilms was investigated by a Z-scan setup using a continued wave He-Ne laser. Results showed that GQDs decreased the extinction coefficient and changed the sign and exact value of the nonlinear refractive index of malignant ovarian cells noticeably. The nonlinear refractive index of studied cells with no GQDs treatment was in the order of 10-8 (cm2/w) with a positive sign. This quantity changed to the same order of magnitude with a negative sign after GQDs treatment. Thus, GQDs can be used for cancer diagnosis under laser irradiation.

Spatially variant red blood cell crenation in alternating current non-uniform fields.

PubMed

An, Ran; Wipf, David O; Minerick, Adrienne R

2014-03-01

Alternating-current (AC) electrokinetics involve the movement and behaviors of particles or cells. Many applications, including dielectrophoretic manipulations, are dependent upon charge interactions between the cell or particle and the surrounding medium. Medium concentrations are traditionally treated as spatially uniform in both theoretical models and experiments. Human red blood cells (RBCs) are observed to crenate, or shrink due to changing osmotic pressure, over 10 min experiments in non-uniform AC electric fields. Cell crenation magnitude is examined as functions of frequency from 250 kHz to 1 MHz and potential from 10 Vpp to 17.5 Vpp over a 100 μm perpendicular electrode gap. Experimental results show higher peak to peak potential and lower frequency lead to greater cell volume crenation up to a maximum volume loss of 20%. A series of experiments are conducted to elucidate the physical mechanisms behind the red blood cell crenation. Non-uniform and uniform electrode systems as well as high and low ion concentration experiments are compared and illustrate that AC electroporation, system temperature, rapid temperature changes, medium pH, electrode reactions, and convection do not account for the crenation behaviors observed. AC electroosmotic was found to be negligible at these conditions and AC electrothermal fluid flows were found to reduce RBC crenation behaviors. These cell deformations were attributed to medium hypertonicity induced by ion concentration gradients in the spatially nonuniform AC electric fields.

Functional engraftment of the medial ganglionic eminence cells in experimental stroke model.

PubMed

Daadi, Marcel M; Lee, Sang Hyung; Arac, Ahmet; Grueter, Brad A; Bhatnagar, Rishi; Maag, Anne-Lise; Schaar, Bruce; Malenka, Robert C; Palmer, Theo D; Steinberg, Gary K

2009-01-01

Currently there are no effective treatments targeting residual anatomical and behavioral deficits resulting from stroke. Evidence suggests that cell transplantation therapy may enhance functional recovery after stroke through multiple mechanisms. We used a syngeneic model of neural transplantation to explore graft-host communications that enhance cellular engraftment.The medial ganglionic eminence (MGE) cells were derived from 15-day-old transgenic rat embryos carrying green fluorescent protein (GFP), a marker, to easily track the transplanted cells. Adult rats were subjected to transient intraluminal occlusion of the medial cerebral artery. Two weeks after stroke, the grafts were deposited into four sites, along the rostro-caudal axis and medially to the stroke in the penumbra zone. Control groups included vehicle and fibroblast transplants. Animals were subjected to motor behavioral tests at 4 week posttransplant survival time. Morphological analysis demonstrated that the grafted MGE cells differentiated into multiple neuronal subtypes, established synaptic contact with host cells, increased the expression of synaptic markers, and enhanced axonal reorganization in the injured area. Initial patch-clamp recording demonstrated that the MGE cells received postsynaptic currents from host cells. Behavioral analysis showed reduced motor deficits in the rotarod and elevated body swing tests. These findings suggest that graft-host interactions influence the fate of grafted neural precursors and that functional recovery could be mediated by neurotrophic support, new synaptic circuit elaboration, and enhancement of the stroke-induced neuroplasticity.

Immobilization of heparin/poly-(L)-lysine nanoparticles on dopamine-coated surface to create a heparin density gradient for selective direction of platelet and vascular cells behavior.

PubMed

Liu, Tao; Liu, Yang; Chen, Yuan; Liu, Shihui; Maitz, Manfred F; Wang, Xue; Zhang, Kun; Wang, Jian; Wang, Yuan; Chen, Junying; Huang, Nan

2014-05-01

Restenosis, thrombosis formation and delayed endothelium regeneration continue to be problematic for coronary artery stent therapy. To improve the hemocompatibility of the cardiovascular implants and selectively direct vascular cell behavior, a novel kind of heparin/poly-l-lysine (Hep/PLL) nanoparticle was developed and immobilized on a dopamine-coated surface. The stability and structural characteristics of the nanoparticles changed with the Hep:PLL concentration ratio. A Hep density gradient was created on a surface by immobilizing nanoparticles with various Hep:PLL ratios on a dopamine-coated surface. Antithrombin III binding quantity was significantly enhanced, and in plasma the APTT and TT times as coagulation tests were prolonged, depending on the Hep density. A low Hep density is sufficient to prevent platelet adhesion and activation. The sensitivity of vascular cells to the Hep density is very different: high Hep density inhibits the growth of all vascular cells, while low Hep density could selectively inhibit smooth muscle cell hyperplasia but promote endothelial progenitor cells and endothelial cell proliferation. These observations provide important guidance for modification of surface heparinization. We suggest that this method will provide a potential means to construct a suitable platform on a stent surface for selective direction of vascular cell behavior with low side effects. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Bioglass promotes wound healing by affecting gap junction connexin 43 mediated endothelial cell behavior.

PubMed

Li, Haiyan; He, Jin; Yu, Hongfei; Green, Colin R; Chang, Jiang

2016-04-01

It is well known that gap junctions play an important role in wound healing, and bioactive glass (BG) has been shown to help healing when applied as a wound dressing. However, the effects of BG on gap junctional communication between cells involved in wound healing is not well understood. We hypothesized that BG may be able to affect gap junction mediated cell behavior to enhance wound healing. Therefore, we set out to investigate the effects of BG on gap junction related behavior of endothelial cells in order to elucidate the mechanisms through which BG is operating. In in vitro studies, BG ion extracts prevented death of human umbilical vein endothelial cells (HUVEC) following hypoxia in a dose dependent manner, possibly through connexin hemichannel modulation. In addition, BG showed stimulatory effects on gap junction communication between HUVECs and upregulated connexin43 (Cx43) expression. Furthermore, BG prompted expression of vascular endothelial growth factor and basic fibroblast growth factor as well as their receptors, and vascular endothelial cadherin in HUVECs, all of which are beneficial for vascularization. In vivo wound healing results showed that the wound closure of full-thickness excisional wounds of rats was accelerated by BG with reduced inflammation during initial stages of healing and stimulated angiogenesis during the proliferation stage. Therefore, BG can stimulate wound healing through affecting gap junctions and gap junction related endothelial cell behaviors, including prevention of endothelial cell death following hypoxia, stimulation of gap junction communication and upregulation of critical vascular growth factors, which contributes to the enhancement of angiogenesis in the wound bed and finally to accelerate wound healing. Although many studies have reported that BG stimulates angiogenesis and wound healing, this work reveals the relationship between BG and gap junction connexin 43 mediated endothelial cell behavior and elucidates one of the possible mechanisms through which BG stimulates wound healing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Close Encounters of Lymphoid Cells and Bacteria

PubMed Central

Cruz-Adalia, Aranzazu; Veiga, Esteban

2016-01-01

During infections, the first reaction of the host against microbial pathogens is carried out by innate immune cells, which recognize conserved structures on pathogens, called pathogen-associated molecular patterns. Afterward, some of these innate cells can phagocytose and destroy the pathogens, secreting cytokines that would modulate the immune response to the challenge. This rapid response is normally followed by the adaptive immunity, more specific and essential for a complete pathogen clearance in many cases. Some innate immune cells, usually named antigen-presenting cells, such as macrophages or dendritic cells, are able to process internalized invaders and present their antigens to lymphocytes, triggering the adaptive immune response. Nevertheless, the traditional boundary of separated roles between innate and adaptive immunity has been blurred by several studies, showing that very specialized populations of lymphocytes (cells of the adaptive immunity) behave similarly to cells of the innate immunity. These “innate-like” lymphocytes include γδ T cells, invariant NKT cells, B-1 cells, mucosal-associated invariant T cells, marginal zone B cells, and innate response activator cells, and together with the newly described innate lymphoid cells are able to rapidly respond to bacterial infections. Strikingly, our recent data suggest that conventional CD4+ T cells, the paradigm of cells of the adaptive immunity, also present innate-like behavior, capturing bacteria in a process called transinfection. Transinfected CD4+ T cells digest internalized bacteria like professional phagocytes and secrete large amounts of proinflammatory cytokines, protecting for further bacterial challenges. In the present review, we will focus on the data showing such innate-like behavior of lymphocytes following bacteria encounter. PMID:27774092

In Vivo Analysis of Alternative Modes of Breast Cancer Cell Invasion

DTIC Science & Technology

2010-05-01

mouse mammary tumor cells was characterized in 3-D culture by time-lapse videomicroscopy . Bright field time-lapse videomicroscopy revealed that the...role that cell signalling pathways play in tumor cell behavior. Working with 3-D gels and time-lapse videomicroscopy I have also gained an

3D printing of biomimetic microstructures for cancer cell migration.

PubMed

Huang, Tina Qing; Qu, Xin; Liu, Justin; Chen, Shaochen

2014-02-01

To understand the physical behavior and migration of cancer cells, a 3D in vitro micro-chip in hydrogel was created using 3D projection printing. The micro-chip has a honeycomb branched structure, aiming to mimic 3D vascular morphology to test, monitor, and analyze differences in the behavior of cancer cells (i.e. HeLa) vs. non-cancerous cell lines (i.e. 10 T1/2). The 3D Projection Printing system can fabricate complex structures in seconds from user-created designs. The fabricated microstructures have three different channel widths of 25, 45, and 120 microns wide to reflect a range of blood vessel diameters. HeLa and 10 T1/2 cells seeded within the micro-chip were then analyzed for morphology and cell migration speed. 10 T1/2 cells exhibited greater changes in morphology due to channel size width than HeLa cells; however, channel width had a limited effect on 10 T1/2 cell migration while HeLa cancer cell migration increased as channel width decreased. This physiologically relevant 3D cancer tissue model has the potential to be a powerful tool for future drug discoveries and cancer migration studies.

Culture conditions defining glioblastoma cells behavior: what is the impact for novel discoveries?

PubMed

Ledur, Pítia Flores; Onzi, Giovana Ravizzoni; Zong, Hui; Lenz, Guido

2017-09-15

In cancer research, the use of established cell lines has gradually been replaced by primary cell cultures due to their better representation of in vivo cancer cell behaviors. However, a major challenge with primary culture involves the finding of growth conditions that minimize alterations in the biological state of the cells. To ensure reproducibility and translational potentials for research findings, culture conditions need to be chosen so that the cell population in culture best mimics tumor cells in vivo . Glioblastoma (GBM) is one of the most aggressive and heterogeneous tumor types and the GBM research field would certainly benefit from culture conditions that could maintain the original plethora of phenotype of the cells. Here, we review culture media and supplementation options for GBM cultures, the rationale behind their use, and how much those choices affect drug-screening outcomes. We provide an overview of 120 papers that use primary GBM cultures and discuss the current predominant conditions. We also show important primary research data indicating that "mis-cultured" glioma cells can acquire unnatural drug sensitivity, which would have devastating effects for clinical translations. Finally, we propose the concurrent test of four culture conditions to minimize the loss of cell coverage in culture.

Flexible magnetic polyurethane/Fe2O3 nanoparticles as organic-inorganic nanocomposites for biomedical applications: Properties and cell behavior.

PubMed

Shahrousvand, Mohsen; Hoseinian, Monireh Sadat; Ghollasi, Marzieh; Karbalaeimahdi, Ali; Salimi, Ali; Tabar, Fatemeh Ahmadi

2017-05-01

Nowadays, the discovery of cell behaviors and their responses in communication with the stem cell niches and/or microenvironments are one of the major topics in tissue engineering and regenerative medicine. In this study, incorporated organic-inorganic polyurethane (PU) nanocomposites were prepared for better understanding of cell signaling and the effect of magnetite nanoparticles on cell proliferation and cell responses. The properties of PU-IONs were evaluated by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic-force microscopy (AFM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). The presence of the iron oxide nanoparticles (IONs) affects on the properties of polyurethane nanocomposites such as bulk morphology, mechanical, electrochemical, and biological properties. The electrical conductivity and hydrophilicity of PU-IONs were improved by increasing the magnetite nanoparticles; therefore water absorption, biodegradation and cell viability were changed. The biocompatibility of PU-IONs was investigated by MTT assay, cell attachment and cell staining. According to the results, the magnetite polyurethane nanocomposites could be a potential choice for cell therapy and tissue engineering, especially nerve repair. Copyright © 2016 Elsevier B.V. All rights reserved.

Cytoplasmic motion induced by cytoskeleton stretching and its effect on cell mechanics.

PubMed

Zhang, T

2011-09-01

Cytoplasmic motion assumed as a steady state laminar flow induced by cytoskeleton stretching in a cell is determined and its effect on the mechanical behavior of the cell under externally applied forces is demonstrated. Non-Newtonian fluid is assumed for the multiphase cytoplasmic fluid and the analytical velocity field around the macromolecular chain is obtained by solving the reduced nonlinear momentum equation using homotopy technique. The entropy generation by the fluid internal friction is calculated and incorporated into the entropic elasticity based 8-chain constitutive relations. Numerical examples showed strengthening behavior of cells in response to externally applied mechanical stimuli. The spatial distribution of the stresses within a cell under externally applied fluid flow forces were also studied.

Using cell deformation and motion to predict forces and collective behavior in morphogenesis.

PubMed

Merkel, Matthias; Manning, M Lisa

2017-07-01

In multi-cellular organisms, morphogenesis translates processes at the cellular scale into tissue deformation at the scale of organs and organisms. To understand how biochemical signaling regulates tissue form and function, we must understand the mechanical forces that shape cells and tissues. Recent progress in developing mechanical models for tissues has led to quantitative predictions for how cell shape changes and polarized cell motility generate forces and collective behavior on the tissue scale. In particular, much insight has been gained by thinking about biological tissues as physical materials composed of cells. Here we review these advances and discuss how they might help shape future experiments in developmental biology. Copyright © 2016 Elsevier Ltd. All rights reserved.

Adult multipotent stromal cell cryopreservation: Pluses and pitfalls

PubMed Central

Duan, Wei; Hicok, Kevin

2017-01-01

Abstract Study and clinical testing of adult multipotent stromal cells (MSCs) are central to progressive improvements in veterinary regenerative medicine. Inherent limitations to long‐term culture preclude use for storage. Until cell line creation from primary isolates becomes routine, MSC stasis at cryogenic temperatures is required for this purpose. Many protocols and reagents, including cryoprotectants, used for veterinary MSCs are derived from those for human and rodent cells. Dissimilarities in cryopreservation strategies play a role in variable MSC behaviors. Familiarity with contemporary cryopreservation reagents and processes is essential to an appreciation of their impact on MSC survival and post‐cryopreservation behavior. In addition to these points, this review includes a brief history and description of current veterinary stem cell regulation. PMID:29023790

Envisioning migration: Mathematics in both experimental analysis and modeling of cell behavior

PubMed Central

Zhang, Elizabeth R.; Wu, Lani F.; Altschuler, Steven J.

2013-01-01

The complex nature of cell migration highlights the power and challenges of applying mathematics to biological studies. Mathematics may be used to create model equations that recapitulate migration, which can predict phenomena not easily uncovered by experiments or intuition alone. Alternatively, mathematics may be applied to interpreting complex data sets with better resolution—potentially empowering scientists to discern subtle patterns amid the noise and heterogeneity typical of migrating cells. Iteration between these two methods is necessary in order to reveal connections within the cell migration signaling network, as well as to understand the behavior that arises from those connections. Here, we review recent quantitative analysis and mathematical modeling approaches to the cell migration problem. PMID:23660413

Envisioning migration: mathematics in both experimental analysis and modeling of cell behavior.

PubMed

Zhang, Elizabeth R; Wu, Lani F; Altschuler, Steven J

2013-10-01

The complex nature of cell migration highlights the power and challenges of applying mathematics to biological studies. Mathematics may be used to create model equations that recapitulate migration, which can predict phenomena not easily uncovered by experiments or intuition alone. Alternatively, mathematics may be applied to interpreting complex data sets with better resolution--potentially empowering scientists to discern subtle patterns amid the noise and heterogeneity typical of migrating cells. Iteration between these two methods is necessary in order to reveal connections within the cell migration signaling network, as well as to understand the behavior that arises from those connections. Here, we review recent quantitative analysis and mathematical modeling approaches to the cell migration problem. Copyright © 2013 Elsevier Ltd. All rights reserved.

Negative thermal quenching of the defects in GaInP top cell with temperature-dependent photoluminescence analysis

NASA Astrophysics Data System (ADS)

Junling, Wang; Rui, Wu; Tiancheng, Yi; Yong, Zheng; Rong, Wang

2018-01-01

Temperature-dependent photoluminescence (PL) measurements were carried out to investigate the irradiation effects of 1.0 MeV electrons on the n+- p GaInP top cell of GaInP/GaAs/Ge triple-junction solar cells in the 10-300 K temperature range. The PL intensities plotted against inverse temperature in an Arrhenius plot shows a thermal quenching behavior from 10 K to 140 K and an unusual negative thermal quenching (NTQ) behavior from 150 K to 300 K. The appearance of the PL thermal quenching with increasing temperature confirms that there is a nonradiative recombination center, i.e., the H2 hole trap located at Ev + 0.55 eV, in the cell after electron irradiation. The PL negative thermal quenching behavior may tentatively be attributed to the intermediate states at an energy level of 0.05 eV within the band gap in GaInP top cell.

A novel function for Foxm1 in interkinetic nuclear migration in the developing telencephalon and anxiety-related behavior.

PubMed

Wu, Xiaojing; Gu, Xiaochun; Han, Xiaoning; Du, Ailing; Jiang, Yan; Zhang, Xiaoyun; Wang, Yanjie; Cao, Guangliang; Zhao, Chunjie

2014-01-22

Interkinetic nuclear migration (INM) is a key feature of cortical neurogenesis. INM functions to maximize the output of the neuroepithelium, and more importantly, balance the self-renewal and differentiation of the progenitors. Although INM has been reported to be highly correlated with the cell cycle, little is known about the effects of cell cycle regulators on INM. In this study, by crossing Foxm1(fl/fl) mice with Emx1-Cre line, we report that a conditional disruption of forkhead transcription factor M1 (Foxm1) in dorsal telencephalon results in abnormal cell cycle progression, leading to impaired INM through the downregulation of Cyclin b1 and Cdc25b. The impairment of INM disturbs the synchronization of apical progenitors (APs) and promotes the transition from APs to basal progenitors (BPs) in a cell-autonomous fashion. Moreover, ablation of Foxm1 causes anxiety-related behaviors in adulthood. Thus, this study provides evidence of linkages among the cell cycle regulator Foxm1, INM, and adult behavior.

Wide-range stiffness gradient PVA/HA hydrogel to investigate stem cell differentiation behavior.

PubMed

Oh, Se Heang; An, Dan Bi; Kim, Tae Ho; Lee, Jin Ho

2016-04-15

Although stiffness-controllable substrates have been developed to investigate the effect of stiffness on cell behavior and function, the use of separate substrates with different degrees of stiffness, substrates with a narrow range stiffness gradient, toxicity of residues, different surface composition, complex fabrication procedures/devices, and low cell adhesion are still considered as hurdles of conventional techniques. In this study, a cylindrical polyvinyl alcohol (PVA)/hyaluronic acid (HA) hydrogel with a wide-range stiffness gradient (between ∼20kPa and ∼200kPa) and cell adhesiveness was prepared by a liquid nitrogen (LN2)-contacting gradual freezing-thawing method that does not use any additives or specific devices to produce the stiffness gradient hydrogel. From an in vitro cell culture using the stiffness gradient PVA/HA hydrogel, it was observed that human bone marrow mesenchymal stem cells have favorable stiffness ranges for induction of differentiation into specific cell types (∼20kPa for nerve cell, ∼40kPa for muscle cell, ∼80kPa for chondrocyte, and ∼190kPa for osteoblast). The PVA/HA hydrogel with a wide range of stiffness spectrum can be a useful tool for basic studies related with the stem cell differentiation, cell reprogramming, cell migration, and tissue regeneration in terms of substrate stiffness. It is postulated that the stiffness of the extracellular matrix influences cell behavior. To prove this concept, various techniques to prepare substrates with a stiffness gradient have been developed. However, the narrow ranges of stiffness gradient and complex fabrication procedures/devices are still remained as limitations. Herein, we develop a substrate (hydrogel) with a wide-range stiffness gradient using a gradual freezing-thawing method which does not need specific devices to produce a stiffness gradient hydrogel. From cell culture experiments using the hydrogel, it is observed that human bone marrow mesenchymal stem cells have favorable stiffness ranges for induction of differentiation into specific cell types (∼20kPa for nerve, ∼40kPa for muscle, ∼80kPa for cartilage, and ∼190kPa for bone in our hydrogel system). Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Laminar-specific Scaling Down of Balanced Excitation and Inhibition in Auditory Cortex by Active Behavioral States

PubMed Central

Zhou, Mu; Liang, Feixue; Xiong, Xiaorui R.; Li, Lu; Li, Haifu; Xiao, Zhongju; Tao, Huizhong W.; Zhang, Li I.

2014-01-01

Cortical sensory processing is modulated by behavioral and cognitive states. How the modulation is achieved through impacting synaptic circuits remains largely unknown. In awake mouse auditory cortex, we reported that sensory-evoked spike responses of layer 2/3 (L2/3) excitatory cells were scaled down with preserved sensory tuning when animals transitioned from quiescence to active behaviors, while L4 and thalamic responses were unchanged. Whole-cell voltage-clamp recordings further revealed that tone-evoked synaptic excitation and inhibition exhibited a robust functional balance. Changes of behavioral state caused scaling down of excitation and inhibition at an approximately equal level in L2/3 cells, but no synaptic changes in L4 cells. This laminar-specific gain control could be attributed to an enhancement of L1–mediated inhibitory tone, with L2/3 parvalbumin inhibitory neurons suppressed as well. Thus, L2/3 circuits can adjust the salience of output in accordance with momentary behavioral demands while maintaining the sensitivity and quality of sensory processing. PMID:24747575

Hybrid multiscale modeling and prediction of cancer cell behavior

PubMed Central

Habibi, Jafar

2017-01-01

Background Understanding cancer development crossing several spatial-temporal scales is of great practical significance to better understand and treat cancers. It is difficult to tackle this challenge with pure biological means. Moreover, hybrid modeling techniques have been proposed that combine the advantages of the continuum and the discrete methods to model multiscale problems. Methods In light of these problems, we have proposed a new hybrid vascular model to facilitate the multiscale modeling and simulation of cancer development with respect to the agent-based, cellular automata and machine learning methods. The purpose of this simulation is to create a dataset that can be used for prediction of cell phenotypes. By using a proposed Q-learning based on SVR-NSGA-II method, the cells have the capability to predict their phenotypes autonomously that is, to act on its own without external direction in response to situations it encounters. Results Computational simulations of the model were performed in order to analyze its performance. The most striking feature of our results is that each cell can select its phenotype at each time step according to its condition. We provide evidence that the prediction of cell phenotypes is reliable. Conclusion Our proposed model, which we term a hybrid multiscale modeling of cancer cell behavior, has the potential to combine the best features of both continuum and discrete models. The in silico results indicate that the 3D model can represent key features of cancer growth, angiogenesis, and its related micro-environment and show that the findings are in good agreement with biological tumor behavior. To the best of our knowledge, this paper is the first hybrid vascular multiscale modeling of cancer cell behavior that has the capability to predict cell phenotypes individually by a self-generated dataset. PMID:28846712

Feasibility of silica-hybridized collagen hydrogels as three-dimensional cell matrices for hard tissue engineering.

PubMed

Yu, Hye-Sun; Lee, Eun-Jung; Seo, Seog-Jin; Knowles, Jonathan C; Kim, Hae-Won

2015-09-01

Exploiting hydrogels for the cultivation of stem cells, aiming to provide them with physico-chemical cues suitable for osteogenesis, is a critical demand for bone engineering. Here, we developed hybrid compositions of collagen and silica into hydrogels via a simple sol-gel process. The physico-chemical and mechanical properties, degradation behavior, and bone-bioactivity were characterized in-depth; furthermore, the in vitro mesenchymal stem cell growth and osteogenic differentiation behaviors within the 3D hybrid gel matrices were communicated for the first time. The hydrolyzed and condensed silica phase enabled chemical links with the collagen fibrils to form networked hybrid gels. The hybrid gels showed improved chemical stability and greater resistance to enzymatic degradation. The in vitro apatite-forming ability was enhanced by the hybrid composition. The viscoelastic mechanical properties of the hybrid gels were significantly improved in terms of the deformation resistance to an applied load and the modulus values under a dynamic oscillation. Mesenchymal stem cells adhered well to the hybrid networks and proliferated actively with substantial cytoskeletal extensions within the gel matrices. Of note, the hybrid gels substantially reduced the cell-mediated gel contraction behaviors, possibly due to the stiffer networks and higher resistance to cell-mediated degradation. Furthermore, the osteogenic differentiation of cells, including the expression of bone-associated genes and protein, was significantly upregulated within the hybrid gel matrices. Together with the physico-chemical and mechanical properties, the cellular behaviors observed within 3D gel matrices, being different from the previous approaches reported on 2D substrates, provide new information on the feasibility and usefulness of the silica-collagen system for stem cell culture and tissue engineering of hard tissues. © The Author(s) 2015.

Spontaneous locomotor activity correlates with the degranulation of mast cells in the meninges rather than in the thalamus: disruptive effect of cocaine.

PubMed

Larson, Alice A; Thomas, Mark J; McElhose, Alex; Kovács, Katalin J

2011-06-13

Mast cells are located in the central nervous system (CNS) of many mammals and stress induces their degranulation. We postulated that mast cells are associated with wakefulness and stimulatory tone in the CNS, as reflected by spontaneous motor activity. Because stress also precipitates drug-seeking behavior in cocaine addicts, we also postulated that cocaine manifests its effects through this relationship. We investigated the influence of single and repeated injections of cocaine on circulating corticosterone, motor activity and degranulation of mast cells in both the thalamus and meninges of mice. Mice were subjected to 5 consecutive days of cocaine or saline followed by a single injection of cocaine or saline 11 days later. Spontaneous locomotor activity was measure for 1h after the final injection before death. Neither a single injection nor prior treatment with cocaine increased motor activity compared to saline-injected controls, however, repeated administration of cocaine induced a significant sensitization to its behavioral effect when delivered 11 days later. In mice that received only saline, motor activity correlated positively with mast cell degranulation in the meninges but not in the thalamus. Cocaine, regardless of the treatment schedule, disrupted this correlation. The concentration of corticosterone did not differ amongst groups and did not correlate with either behavior or mast cell parameters in any group. The correlation between behavioral activity and the mast cell degranulation in the meninges suggests that these parameters are linked. The disruptive effect of cocaine on this relationship indicates a role downstream from mast cells in the regulation of motor activity. Copyright © 2011 Elsevier B.V. All rights reserved.

Hybrid multiscale modeling and prediction of cancer cell behavior.

PubMed

Zangooei, Mohammad Hossein; Habibi, Jafar

2017-01-01

Understanding cancer development crossing several spatial-temporal scales is of great practical significance to better understand and treat cancers. It is difficult to tackle this challenge with pure biological means. Moreover, hybrid modeling techniques have been proposed that combine the advantages of the continuum and the discrete methods to model multiscale problems. In light of these problems, we have proposed a new hybrid vascular model to facilitate the multiscale modeling and simulation of cancer development with respect to the agent-based, cellular automata and machine learning methods. The purpose of this simulation is to create a dataset that can be used for prediction of cell phenotypes. By using a proposed Q-learning based on SVR-NSGA-II method, the cells have the capability to predict their phenotypes autonomously that is, to act on its own without external direction in response to situations it encounters. Computational simulations of the model were performed in order to analyze its performance. The most striking feature of our results is that each cell can select its phenotype at each time step according to its condition. We provide evidence that the prediction of cell phenotypes is reliable. Our proposed model, which we term a hybrid multiscale modeling of cancer cell behavior, has the potential to combine the best features of both continuum and discrete models. The in silico results indicate that the 3D model can represent key features of cancer growth, angiogenesis, and its related micro-environment and show that the findings are in good agreement with biological tumor behavior. To the best of our knowledge, this paper is the first hybrid vascular multiscale modeling of cancer cell behavior that has the capability to predict cell phenotypes individually by a self-generated dataset.

Environmental enrichment increases the GFAP+ stem cell pool and reverses hypoxia-induced cognitive deficits in juvenile mice.

PubMed

Salmaso, Natalina; Silbereis, John; Komitova, Mila; Mitchell, Patrick; Chapman, Katherine; Ment, Laura R; Schwartz, Michael L; Vaccarino, Flora M

2012-06-27

Premature children born with very low birth weight (VLBW) can suffer chronic hypoxic injury as a consequence of abnormal lung development and cardiovascular abnormalities, often leading to grave neurological and behavioral consequences. Emerging evidence suggests that environmental enrichment improves outcome in animal models of adult brain injury and disease; however, little is known about the impact of environmental enrichment following developmental brain injury. Intriguingly, data on socio-demographic factors from longitudinal studies that examined a number of VLBW cohorts suggest that early environment has a substantial impact on neurological and behavioral outcomes. In the current study, we demonstrate that environmental enrichment significantly enhances behavioral and neurobiological recovery from perinatal hypoxic injury. Using a genetic fate-mapping model that allows us to trace the progeny of GFAP+ astroglial cells, we show that hypoxic injury increases the proportion of astroglial cells that attain a neuronal fate. In contrast, environmental enrichment increases the stem cell pool, both through increased stem cell proliferation and stem cell survival. In mice subjected to hypoxia and subsequent enrichment there is an additive effect of both conditions on hippocampal neurogenesis from astroglia, resulting in a robust increase in the number of neurons arising from GFAP+ cells by the time these mice reach full adulthood.

Visual receptive field properties of cells in the optic tectum of the archer fish.

PubMed

Ben-Tov, Mor; Kopilevich, Ivgeny; Donchin, Opher; Ben-Shahar, Ohad; Giladi, Chen; Segev, Ronen

2013-08-01

The archer fish is well known for its extreme visual behavior in shooting water jets at prey hanging on vegetation above water. This fish is a promising model in the study of visual system function because it can be trained to respond to artificial targets and thus to provide valuable psychophysical data. Although much behavioral data have indeed been collected over the past two decades, little is known about the functional organization of the main visual area supporting this visual behavior, namely, the fish optic tectum. In this article we focus on a fundamental aspect of this functional organization and provide a detailed analysis of receptive field properties of cells in the archer fish optic tectum. Using extracellular measurements to record activities of single cells, we first measure their retinotectal mapping. We then determine their receptive field properties such as size, selectivity for stimulus direction and orientation, tuning for spatial frequency, and tuning for temporal frequency. Finally, on the basis of all these measurements, we demonstrate that optic tectum cells can be classified into three categories: orientation-tuned cells, direction-tuned cells, and direction-agnostic cells. Our results provide an essential basis for future investigations of information processing in the archer fish visual system.

Patterning N-type and S-type neuroblastoma cells with Pluronic F108 and ECM proteins.

PubMed

Corey, Joseph M; Gertz, Caitlyn C; Sutton, Thomas J; Chen, Qiaoran; Mycek, Katherine B; Wang, Bor-Shuen; Martin, Abbey A; Johnson, Sara L; Feldman, Eva L

2010-05-01

Influencing cell shape using micropatterned substrates affects cell behaviors, such as proliferation and apoptosis. Cell shape may also affect these behaviors in human neuroblastoma (NBL) cancer, but to date, no substrate design has effectively patterned multiple clinically important human NBL lines. In this study, we investigated whether Pluronic F108 was an effective antiadhesive coating for human NBL cells and whether it would localize three NBL lines to adhesive regions of tissue culture plastic or collagen I on substrate patterns. The adhesion and patterning of an S-type line, SH-EP, and two N-type lines, SH-SY5Y and IMR-32, were tested. In adhesion assays, F108 deterred NBL adhesion equally as well as two antiadhesive organofunctional silanes and far better than bovine serum albumin. Patterned stripes of F108 restricted all three human NBL lines to adhesive stripes of tissue culture plastic. We then investigated four schemes of applying collagen and F108 to different regions of a substrate. Contact with collagen obliterates the ability of F108 to deter NBL adhesion, limiting how both materials can be applied to substrates to produce high fidelity NBL patterning. This patterned substrate design should facilitate investigations of the role of cell shape in NBL cell behavior. Copyright 2009 Wiley Periodicals, Inc.

Patterning N-type and S-type Neuroblastoma Cells with Pluronic F108 and ECM Proteins

PubMed Central

Corey, Joseph M.; Gertz, Caitlyn C.; Sutton, Thomas J.; Chen, Qiaoran; Mycek, Katherine B.; Wang, Bor-Shuen; Martin, Abbey A.; Johnson, Sara L.; Feldman, Eva L.

2009-01-01

Influencing cell shape using micropatterned substrates affects cell behaviors, such as proliferation and apoptosis. Cell shape may also affect these behaviors in human neuroblastoma (NBL) cancer, but to date, no substrate design has effectively patterned multiple clinically important human NBL lines. In this study, we investigated whether Pluronic F108 was an effective anti-adhesive coating for human NBL cells and whether it would localize three NBL lines to adhesive regions of tissue culture plastic or collagen I on substrate patterns. The adhesion and patterning of an S-type line, SH-EP, and two N-type lines, SH-SY5Y and IMR-32, were tested. In adhesion assays, F108 deterred NBL adhesion equally as well as two anti-adhesive organofunctional silanes and far better than bovine serum albumin. Patterned stripes of F108 restricted all three human NBL lines to adhesive stripes of tissue culture plastic. We then investigated four schemes of applying collagen and F108 to different regions of a substrate. Contact with collagen obliterates the ability of F108 to deter NBL adhesion, limiting how both materials can be applied to substrates to produce high fidelity NBL patterning. This patterned substrate design should facilitate investigations of the role of cell shape in NBL cell behavior. PMID:19609877

Myeloid dendritic cells frequencies are increased in children with autism spectrum disorder and associated with amygdala volume and repetitive behaviors

PubMed Central

Breece, Elizabeth; Paciotti, Brian; Nordahl, Christine Wu; Ozonoff, Sally; Van de Water, Judy A.; Rogers, Sally J.; Amaral, David; Ashwood, Paul

2012-01-01

The pathophysiology of Autism Spectrum Disorder (ASD) is not yet known; however, studies suggest that dysfunction of the immune system affects many children with ASD. Increasing evidence points to dysfunction of the innate immune system including activation of microglia and perivascular macrophages, increases in inflammatory cytokines/chemokines in brain tissue and CSF, and abnormal peripheral monocyte cell function. Dendritic cells are major players in innate immunity and have important functions in the phagocytosis of pathogens or debris, antigen presentation, activation of naïve T cells, induction of tolerance and cytokine/chemokine production. In this study, we assessed circulating frequencies of myeloid dendritic cells (defined as Lin-1−BDCA1+CD11c+ and Lin-1−BDCA3+CD123−) and plasmacytoid dendritic cells (Lin-1− BDCA2+CD123+ or Lin-1−BDCA4+ CD11c−) in 57 children with ASD, and 29 typically developing controls of the same age, all of who were enrolled as part of the Autism Phenome Project (APP). The frequencies of dendritic cells and associations with behavioral assessment and MRI measurements of amygdala volume were compared in the same participants. The frequencies of myeloid dendritic cells were significantly increased in children with ASD compared to typically developing controls (p < 0.03). Elevated frequencies of myeloid dendritic cells were positively associated with abnormal right and left amygdala enlargement, severity of gastrointestinal symptoms and increased repetitive behaviors. The frequencies of plasmacytoid dendritic cells were also associated with amygdala volumes as well as developmental regression in children with ASD. Dendritic cells play key roles in modulating immune responses and differences in frequencies or functions of these cells may result in immune dysfunction in children with ASD. These data further implicate innate immune cells in the complex pathophysiology of ASD. PMID:23063420

Effects of Long-Term 50Hz Power-Line Frequency Electromagnetic Field on Cell Behavior in Balb/c 3T3 Cells

PubMed Central

An, Guang-Zhou; Xu, Hui; Zhou, Yan; Du, Le; Miao, Xia; Jiang, Da-Peng; Li, Kang-Chu; Guo, Guo-Zhen; Zhang, Chen; Ding, Gui-Rong

2015-01-01

Power-line frequency electromagnetic field (PF-EMF) was reported as a human carcinogen by some epidemiological research, but the conclusion is lack of robust experiment evidence. To identify the effects of long-term PF-EMF exposure on cell behavior, Balb/c 3T3 cells in exponential growth phase were exposed or sham-exposed to 50 Hertz (Hz) PF-EMF at 2.3 mT for 2 hours (h) one day, 5 days every week. After 11 weeks exposure, cells were collected instantly. Cell morphology was observed under invert microscope and Giemsa staining, cell viability was detected by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, cell cycle and apoptosis was examined by flow cytometry, the protein level of Proliferating Cell Nuclear Antigen (PCNA) and CyclinD1 was detected by western blot, cell transformation was examined by soft agar clone assay and plate clone forming test, and cell migration ability was observed by scratch adhesion test. It was found that after PF-EMF exposure, cell morphology, apoptosis, cell migration ability and cell transformation didn’t change. However, compared with sham group, cell viability obviously decreased and cell cycle distribution also changed after 11 weeks PF-EMF exposure. Meanwhile, the protein level of PCNA and CyclinD1 significantly decreased after PF-EMF exposure. These data suggested that although long-term 50Hz PF-EMF exposure under this experimental condition had no effects on apoptosis, cell migration ability and cell transformation, it could affect cell proliferation and cell cycle by down-regulation the expression of PCNA and CyclinD1 protein. PMID:25695503

Effects of long-term 50Hz power-line frequency electromagnetic field on cell behavior in Balb/c 3T3 cells.

PubMed

An, Guang-Zhou; Xu, Hui; Zhou, Yan; Du, Le; Miao, Xia; Jiang, Da-Peng; Li, Kang-Chu; Guo, Guo-Zhen; Zhang, Chen; Ding, Gui-Rong

2015-01-01

Power-line frequency electromagnetic field (PF-EMF) was reported as a human carcinogen by some epidemiological research, but the conclusion is lack of robust experiment evidence. To identify the effects of long-term PF-EMF exposure on cell behavior, Balb/c 3T3 cells in exponential growth phase were exposed or sham-exposed to 50 Hertz (Hz) PF-EMF at 2.3 mT for 2 hours (h) one day, 5 days every week. After 11 weeks exposure, cells were collected instantly. Cell morphology was observed under invert microscope and Giemsa staining, cell viability was detected by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, cell cycle and apoptosis was examined by flow cytometry, the protein level of Proliferating Cell Nuclear Antigen (PCNA) and CyclinD1 was detected by western blot, cell transformation was examined by soft agar clone assay and plate clone forming test, and cell migration ability was observed by scratch adhesion test. It was found that after PF-EMF exposure, cell morphology, apoptosis, cell migration ability and cell transformation didn't change. However, compared with sham group, cell viability obviously decreased and cell cycle distribution also changed after 11 weeks PF-EMF exposure. Meanwhile, the protein level of PCNA and CyclinD1 significantly decreased after PF-EMF exposure. These data suggested that although long-term 50Hz PF-EMF exposure under this experimental condition had no effects on apoptosis, cell migration ability and cell transformation, it could affect cell proliferation and cell cycle by down-regulation the expression of PCNA and CyclinD1 protein.

Cancer cell uptake behavior of Au nanoring and its localized surface plasmon resonance induced cell inactivation

NASA Astrophysics Data System (ADS)

Chu, Che-Kuan; Tu, Yi-Chou; Chang, Yu-Wei; Chu, Chih-Ken; Chen, Shih-Yang; Chi, Ting-Ta; Kiang, Yean-Woei; Yang, Chih-Chung

2015-02-01

Au nanorings (NRIs), which have the localized surface plasmon resonance (LSPR) wavelength around 1058 nm, either with or without linked antibodies, are applied to SAS oral cancer cells for cell inactivation through the LSPR-induced photothermal effect when they are illuminated by a laser of 1065 nm in wavelength. Different incubation times of cells with Au NRIs are considered for observing the variations of cell uptake efficiency of Au NRI and the threshold laser intensity for cell inactivation. In each case of incubation time, the cell sample is washed for evaluating the total Au NRI number per cell adsorbed and internalized by the cells based on inductively coupled plasma mass spectrometry measurement. Also, the Au NRIs remaining on cell membrane are etched with KI/I2 solution to evaluate the internalized Au NRI number per cell. The threshold laser intensities for cell inactivation before washout, after washout, and after KI/I2 etching are calibrated from the circular area sizes of inactivated cells around the illuminated laser spot center with various laser power levels. By using Au NRIs with antibodies, the internalized Au NRI number per cell increases monotonically with incubation time up to 24 h. However, the number of Au NRI remaining on cell membrane reaches a maximum at 12 h in incubation time. The cell uptake behavior of an Au NRI without antibodies is similar to that with antibodies except that the uptake NRI number is significantly smaller and the incubation time for the maximum NRI number remaining on cell membrane is delayed to 20 h. By comparing the threshold laser intensities before and after KI/I2 etching, it is found that the Au NRIs remaining on cell membrane cause more effective cancer cell inactivation, when compared with the internalized Au NRIs.

Quantum dot-based molecular imaging of cancer cell growth using a clone formation assay.

PubMed

Geng, Xia-Fei; Fang, Min; Liu, Shao-Ping; Li, Yan

2016-10-01

This aim of the present study was to investigate clonal growth behavior and analyze the proliferation characteristics of cancer cells. The MCF‑7 human breast cancer cell line, SW480 human colon cancer cell line and SGC7901 human gastric cancer cell line were selected to investigate the morphology of cell clones. Quantum dot‑based molecular targeted imaging techniques (which stained pan‑cytokeratin in the cytoplasm green and Ki67 in the cell nucleus yellow or red) were used to investigate the clone formation rate, cell morphology, discrete tendency, and Ki67 expression and distribution in clones. From the cell clone formation assay, the MCF‑7, SW480 and SGC7901 cells were observed to form clones on days 6, 8 and 12 of cell culture, respectively. These three types of cells had heterogeneous morphology, large nuclear:cytoplasmic ratios, and conspicuous pathological mitotic features. The cells at the clone periphery formed multiple pseudopodium. In certain clones, cancer cells at the borderline were separated from the central cell clusters or presented a discrete tendency. With quantum dot‑based molecular targeted imaging techniques, cells with strong Ki67 expression were predominantly shown to be distributed at the clone periphery, or concentrated on one side of the clones. In conclusion, cancer cell clones showed asymmetric growth behavior, and Ki67 was widely expressed in clones of these three cell lines, with strong expression around the clones, or aggregated at one side. Cell clone formation assay based on quantum dots molecular imaging offered a novel method to study the proliferative features of cancer cells, thus providing a further insight into tumor biology.

ANT2 expression under hypoxic conditions produces opposite cell-cycle behavior in 143B and HepG2 cancer cells.

PubMed

Chevrollier, Arnaud; Loiseau, Dominique; Gautier, Fabien; Malthièry, Yves; Stepien, Georges

2005-01-01

Under hypoxic conditions, mitochondrial ATP production ceases, leaving cells entirely dependent on their glycolytic metabolism. The cytoplasmic and intramitochondrial ATP/ADP ratios, partly controlled by the adenine nucleotide translocator (ANT), are drastically modified. In dividing and growing cells that have a predominantly glycolytic metabolism, the ANT isoform 2, which has kinetic properties allowing ATP import into mitochondria, is over-expressed in comparison to control cells. We studied the cellular metabolic and proliferative response to hypoxia in two transformed human cell lines with different metabolic backgrounds: HepG2 and 143B, and in their rho(o) derivatives, i.e., cells with no mitochondrial DNA. Transformed 143B and rho(o) cells continued their proliferation whereas HepG2 cells, with a more differentiated phenotype, arrested their cell-cycle at the G(1)/S checkpoint. Hypoxia induced an increase in glycolytic activity, correlated to an induction of VEGF and hexokinase II (HK II) expression. Thus, according to their tumorigenicity, transformed cells may adopt one of two distinct behaviors to support hypoxic stress, i.e., proliferation or quiescence. Our study links the constitutive glycolytic activity and ANT2 expression levels of transformed cells with the loss of cell-cycle control after oxygen deprivation. ATP import by ANT2 allows cells to maintain their mitochondrial integrity while acquiring insensitivity to any alterations in the proteins involved in oxidative phosphorylation. This loss of cell dependence on oxidative metabolism is an important factor in the development of tumors.

E-Cadherin-Dependent Stimulation of Traction Force at Focal Adhesions via the Src and PI3K Signaling Pathways

PubMed Central

Jasaitis, Audrius; Estevez, Maruxa; Heysch, Julie; Ladoux, Benoit; Dufour, Sylvie

2012-01-01

The interplay between cadherin- and integrin-dependent signals controls cell behavior, but the precise mechanisms that regulate the strength of adhesion to the extracellular matrix remains poorly understood. We deposited cells expressing a defined repertoire of cadherins and integrins on fibronectin (FN)-coated polyacrylamide gels (FN-PAG) and on FN-coated pillars used as a micro-force sensor array (μFSA), and analyzed the functional relationship between these adhesion receptors to determine how it regulates cell traction force. We found that cadherin-mediated adhesion stimulated cell spreading on FN-PAG, and this was modulated by the substrate stiffness. We compared S180 cells with cells stably expressing different cadherins on μFSA and found that traction forces were stronger in cells expressing cadherins than in parental cells. E-cadherin-mediated contact and mechanical coupling between cells are required for this increase in cell-FN traction force, which was not observed in isolated cells, and required Src and PI3K activities. Traction forces were stronger in cells expressing type I cadherins than in cells expressing type II cadherins, which correlates with our previous observation of a higher intercellular adhesion strength developed by type I compared with type II cadherins. Our results reveal one of the mechanisms whereby molecular cross talk between cadherins and integrins upregulates traction forces at cell-FN adhesion sites, and thus provide additional insight into the molecular control of cell behavior. PMID:22853894

Collective and single cell behavior in epithelial contact inhibition.

PubMed

Puliafito, Alberto; Hufnagel, Lars; Neveu, Pierre; Streichan, Sebastian; Sigal, Alex; Fygenson, D Kuchnir; Shraiman, Boris I

2012-01-17

Control of cell proliferation is a fundamental aspect of tissue physiology central to morphogenesis, wound healing, and cancer. Although many of the molecular genetic factors are now known, the system level regulation of growth is still poorly understood. A simple form of inhibition of cell proliferation is encountered in vitro in normally differentiating epithelial cell cultures and is known as "contact inhibition." The study presented here provides a quantitative characterization of contact inhibition dynamics on tissue-wide and single cell levels. Using long-term tracking of cultured Madin-Darby canine kidney cells we demonstrate that inhibition of cell division in a confluent monolayer follows inhibition of cell motility and sets in when mechanical constraint on local expansion causes divisions to reduce cell area. We quantify cell motility and cell cycle statistics in the low density confluent regime and their change across the transition to epithelial morphology which occurs with increasing cell density. We then study the dynamics of cell area distribution arising through reductive division, determine the average mitotic rate as a function of cell size, and demonstrate that complete arrest of mitosis occurs when cell area falls below a critical value. We also present a simple computational model of growth mechanics which captures all aspects of the observed behavior. Our measurements and analysis show that contact inhibition is a consequence of mechanical interaction and constraint rather than interfacial contact alone, and define quantitative phenotypes that can guide future studies of molecular mechanisms underlying contact inhibition.

Extracellular matrix components direct porcine muscle stem cell behavior

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

Wilschut, Karlijn J.; Haagsman, Henk P.; Roelen, Bernard A.J., E-mail: b.a.j.roelen@uu.nl

2010-02-01

In muscle tissue, extracellular matrix proteins, together with the vasculature system, muscle-residence cells and muscle fibers, create the niche for muscle stem cells. The niche is important in controlling proliferation and directing differentiation of muscle stem cells to sustain muscle tissue. Mimicking the extracellular muscle environment improves tools exploring the behavior of primary muscle cells. Optimizing cell culture conditions to maintain muscle commitment is important in stem cell-based studies concerning toxicology screening, ex vivo skeletal muscle tissue engineering and in the enhancement of clinical efficiency. We used the muscle extracellular matrix proteins collagen type I, fibronectin, laminin, and also gelatinmore » and Matrigel as surface coatings of tissue culture plastic to resemble the muscle extracellular matrix. Several important factors that determine myogenic commitment of the primary muscle cells were characterized by quantitative real-time RT-PCR and immunofluorescence. Adhesion of high PAX7 expressing satellite cells was improved if the cells were cultured on fibronectin or laminin coatings. Cells cultured on Matrigel and laminin coatings showed dominant integrin expression levels and exhibited an activated Wnt pathway. Under these conditions both stem cell proliferation and myogenic differentiation capacity were superior if compared to cells cultured on collagen type I, fibronectin and gelatin. In conclusion, Matrigel and laminin are the preferred coatings to sustain the proliferation and myogenic differentiation capacity of the primary porcine muscle stem cells, when cells are removed from their natural environment for in vitro culture.« less

Receptor-based differences in human aortic smooth muscle cell membrane stiffness

NASA Technical Reports Server (NTRS)

Huang, H.; Kamm, R. D.; So, P. T.; Lee, R. T.

2001-01-01

Cells respond to mechanical stimuli with diverse molecular responses. The nature of the sensory mechanism involved in mechanotransduction is not known, but integrins may play an important role. The integrins are linked to both the cytoskeleton and extracellular matrix, suggesting that probing cells via integrins should yield different mechanical properties than probing cells via non-cytoskeleton-associated receptors. To test the hypothesis that the mechanical properties of a cell are dependent on the receptor on which the stress is applied, human aortic smooth muscle cells were plated, and magnetic beads, targeted either to the integrins via fibronectin or to the transferrin receptor by use of an IgG antibody, were attached to the cell surface. The resistance of the cell to deformation ("stiffness") was estimated by oscillating the magnetic beads at 1 Hz by use of single-pole magnetic tweezers at 2 different magnitudes. The ratio of bead displacements at different magnitudes was used to explore the mechanical properties of the cells. Cells stressed via the integrins required approximately 10-fold more force to obtain the same bead displacements as the cells stressed via the transferrin receptors. Cells stressed via integrins showed stiffening behavior as the force was increased, whereas this stiffening was significantly less for cells stressed via the transferrin receptor (P<0.001). Mechanical characteristics of vascular smooth muscle cells depend on the receptor by which the stress is applied, with integrin-based linkages demonstrating cell-stiffening behavior.

Collective Signal Processing in Cluster Chemotaxis: Roles of Adaptation, Amplification, and Co-attraction in Collective Guidance

PubMed Central

Camley, Brian A.; Zimmermann, Juliane; Levine, Herbert; Rappel, Wouter-Jan

2016-01-01

Single eukaryotic cells commonly sense and follow chemical gradients, performing chemotaxis. Recent experiments and theories, however, show that even when single cells do not chemotax, clusters of cells may, if their interactions are regulated by the chemoattractant. We study this general mechanism of “collective guidance” computationally with models that integrate stochastic dynamics for individual cells with biochemical reactions within the cells, and diffusion of chemical signals between the cells. We show that if clusters of cells use the well-known local excitation, global inhibition (LEGI) mechanism to sense chemoattractant gradients, the speed of the cell cluster becomes non-monotonic in the cluster’s size—clusters either larger or smaller than an optimal size will have lower speed. We argue that the cell cluster speed is a crucial readout of how the cluster processes chemotactic signals; both amplification and adaptation will alter the behavior of cluster speed as a function of size. We also show that, contrary to the assumptions of earlier theories, collective guidance does not require persistent cell-cell contacts and strong short range adhesion. If cell-cell adhesion is absent, and the cluster cohesion is instead provided by a co-attraction mechanism, e.g. chemotaxis toward a secreted molecule, collective guidance may still function. However, new behaviors, such as cluster rotation, may also appear in this case. Co-attraction and adaptation allow for collective guidance that is robust to varying chemoattractant concentrations while not requiring strong cell-cell adhesion. PMID:27367541

Rheologic and hemodynamic characteristics of red cells of mouse, rat and human.

PubMed

Chen, D; Kaul, D K

1994-01-01

The present study compares hematologic, rheologic and hemodynamic characteristics of red cells from mouse, rat and human. Red cells in these species are biconcave discs that show significant differences in diameter and mean corpuscular volume (MCV). However, differences in mean corpuscular hemoglobin concentration (MCHC) are not significant. Viscosity measurement of washed red cell suspensions (in each case the medium osmolarity adjusted to match plasma osmolarity) showed significant interspecies differences at shear rates of 37.5 and 750 sec-1 as follows: Human > rat > mouse. Hemodynamic and microcirculatory behavior of these red cells was investigated in the artificially perfused ex vivo mesocecum vasculature of the rat. Hemodynamic measurements in the whole ex vivo mesocecum preparation revealed maximal increase in the peripheral resistance unit (PRU) for the human red cells followed by the rat and mouse red cells, respectively at a hematocrit (Hct) of 40%. Further, measurements of red cell velocities (Vrbc) in single arterioles of the mesocecum vasculature, during sustained perfusion with washed red cell suspensions, showed that at any given perfusion pressure (Pa), Vrbc for both mouse and rat red cells was higher than that for human red cells, while Vrbc for mouse red cells was higher than that for the rat. These results demonstrate that the microvascular flow behavior of these red cells is likely to be influenced by both physical and rheologic characteristics.

Electro-thermal analysis of Lithium Iron Phosphate battery for electric vehicles

NASA Astrophysics Data System (ADS)

Saw, L. H.; Somasundaram, K.; Ye, Y.; Tay, A. A. O.

2014-03-01

Lithium ion batteries offer an attractive solution for powering electric vehicles due to their relatively high specific energy and specific power, however, the temperature of the batteries greatly affects their performance as well as cycle life. In this work, an empirical equation characterizing the battery's electrical behavior is coupled with a lumped thermal model to analyze the electrical and thermal behavior of the 18650 Lithium Iron Phosphate cell. Under constant current discharging mode, the cell temperature increases with increasing charge/discharge rates. The dynamic behavior of the battery is also analyzed under a Simplified Federal Urban Driving Schedule and it is found that heat generated from the battery during this cycle is negligible. Simulation results are validated with experimental data. The validated single cell model is then extended to study the dynamic behavior of an electric vehicle battery pack. The modeling results predict that more heat is generated on an aggressive US06 driving cycle as compared to UDDS and HWFET cycle. An extensive thermal management system is needed for the electric vehicle battery pack especially during aggressive driving conditions to ensure that the cells are maintained within the desirable operating limits and temperature uniformity is achieved between the cells.

Basic techniques in mammalian cell tissue culture.

PubMed

Phelan, Katy; May, Kristin M

2015-03-02

Cultured mammalian cells are used extensively in cell biology studies. It requires a number of special skills in order to be able to preserve the structure, function, behavior, and biology of the cells in culture. This unit describes the basic skills required to maintain and preserve cell cultures: maintaining aseptic technique, preparing media with the appropriate characteristics, passaging, freezing and storage, recovering frozen stocks, and counting viable cells. Copyright © 2015 John Wiley & Sons, Inc.

MiR-18a regulates the proliferation, migration and invasion of human glioblastoma cell by targeting neogenin

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

Song, Yichen, E-mail: jeff200064017@163.com; Wang, Ping, E-mail: pingwang8000@163.com; Institute of Pathology and Pathophysiology, China Medical University, Shenyang 110001

MiR-17-92 cluster has recently been reported as an oncogene in some tumors. However, the association of miR-18a, an important member of this cluster, with glioblastoma remains unknown. Therefore, this study aims to investigate the expression of miR-18a in glioblastoma and its role in biological behavior of U87 and U251 human glioblastoma cell lines. Quantitative RT-PCR results showed that miR-18a was highly expressed in glioblastoma tissues and U87 and U251 cell lines compared with that in human brain tissues and primary normal human astrocytes, and the expression levels were increased along with the rising pathological grades of glioblastoma. Neogenin was identifiedmore » as the target gene of miR-18a by dual-luciferase reporter assays. RT-PCR and western blot results showed that its expression levels were decreased along with the rising pathological grades of glioblastoma. Inhibition of miR-18a expression was established by transfecting exogenous miR-18a inhibitor into U87 and U251 cells, and its effects on the biological behavior of glioblastoma cells were studied using CCK-8 assay, transwell assay and flow cytometry. Inhibition of miR-18a expression in U87 and U251 cells significantly up-regulated neogenin, and dramatically suppressed the abilities of cell proliferation, migration and invasion, induced cell cycle arrest and promoted cellular apoptosis. Collectively, these results suggest that miR-18a may regulate biological behavior of human glioblastoma cells by targeting neogenin, and miR-18a can serve as a potential target in the treatment of glioblastoma. - Highlights: • MiR-18a was highly expressed in glioblastoma tissues and U87 and U251 cell lines. • Neogenin was identified as the target gene of miR-18a. • Neogenin expressions were decreased along with the rising pathological grades of glioblastoma. • Inhibition of miR-18a suppressed biological behavior of glioma cells by up-regulating neogenin.« less

SLC12A7 alters adrenocortical carcinoma cell adhesion properties to promote an aggressive invasive behavior.

PubMed

Brown, Taylor C; Murtha, Timothy D; Rubinstein, Jill C; Korah, Reju; Carling, Tobias

2018-06-08

Altered expression of Solute Carrier Family 12 Member 7 (SLC12A7) is implicated to promote malignant behavior in multiple cancer types through an incompletely understood mechanism. Recent studies have shown recurrent gene amplifications and overexpression of SLC12A7 in adrenocortical carcinoma (ACC). The potential mechanistic effect(s) of SLC12A7 amplifications in portending an aggressive behavior in ACC has not been previously studied and is investigated here using two established ACC cell lines, SW-13 and NCI-H295R. SW-13 cells, which express negligible amounts of SLC12A7, were enforced to express SLC12A7 constitutively, while RNAi gene silencing was performed in NCI-H295R cells, which have robust endogenous expression of SLC12A7. In vitro studies tested the outcomes of experimental alterations in SLC12A7 expression on malignant characteristics, including cell viability, growth, colony formation potential, motility, invasive capacity, adhesion and detachment kinetics, and cell membrane organization. Further, potential alterations in transcription regulation downstream to induced SLC12A7 overexpression was explored using targeted transcription factor expression arrays. Enforced SLC12A7 overexpression in SW-13 cells robustly promoted motility and invasive characteristics (p < 0.05) without significantly altering cell viability, growth, or colony formation potential. SLC12A7 overexpression also significantly increased rates of cellular attachment and detachment turnover (p < 0.05), potentially propelled by increased filopodia formation and/or Ezrin interaction. In contrast, RNAi gene silencing of SLC12A7 stymied cell attachment strength as well as migration and invasion capacity in NCI-H295R cells. Transcription factor expression analysis identified multiple signally pathways potentially affected by SLC12A7 overexpression, including osmotic stress, bone morphogenetic protein, and Hippo signaling pathways. Amplification of SLC12A7 observed in ACCs is shown here, in vitro, to exacerbate the malignant behavior of ACC cells by promoting invasive capacities, possibly mediated by alterations in multiple signaling pathways, including the osmotic stress pathway.

DLK1 as a potential target against cancer stem/progenitor cells of hepatocellular carcinoma.

PubMed

Xu, Xiao; Liu, Rui-Fang; Zhang, Xin; Huang, Li-Yu; Chen, Fei; Fei, Qian-Lan; Han, Ze-Guang

2012-03-01

Delta-like 1 homolog (DLK1; Drosophila) is a hepatic stem/progenitor cell marker in fetal livers that plays a vital role in oncogenesis of hepatocellular carcinoma (HCC). The aim of this study is to investigate whether DLK1 could serve as a potential therapeutic target against cancer stem/progenitor cells of HCC. DLK1(+) and DLK1(-) cells were sorted by fluorescence-activated cell sorting and magnetic-activated cell sorting, respectively, and then were evaluated by flow cytometry. The biological behaviors of these isolated cells and those with DLK1 knockdown were assessed by growth curve, colony formation assay, spheroid colony formation, chemoresistance, and in vivo tumorigenicity. Adenovirus-mediated RNA interference was used to knockdown the endogenous DLK1. We found that DLK1(+) population was less than 10% in almost all 17 HCC cell lines examined. DLK1(+) HCC cells showed stronger ability of chemoresistance, colony formation, spheroid colony formation, and in vivo tumorigenicity compared with DLK1(-) cells. The DLK1(+) HCC cells could generate the progeny without DLK1 expression. Furthermore, DLK1 knockdown could suppress the ability of proliferation, colony formation, spheroid colony formation, and in vivo tumorigenicity of Hep3B and Huh-7 HCC cells. Our data suggested that DLK1(+) HCC cells have characteristics similar to those of cancer stem/progenitor cells. RNA interference against DLK1 can suppress the malignant behaviors of HCC cells, possibly through directly disrupting cancer stem/progenitor cells, which suggested that DLK1 could be a potential therapeutic target against the HCC stem/progenitor cells.

Collective Behavior of Amoebae in Thin Films

NASA Astrophysics Data System (ADS)

Bae, Albert

2005-03-01

We have discovered new aspects of social behavior in Dictyostelium discoideum by culturing high density colonies in liquid media depleted of nutrients in confined geometries by using three different preparations: I. thin (15-40um thick) and II. ultrathin (<3um) films of liquid media with a mineral oil overlayer, and III. microfluidic chambers fabricated in PDMS (˜7um tall). We find greatly reduced, if not eliminated, cell on cell layering in the microfluidic system when compared to the wetting layer preparations. The ultrathin films reveal robust behavior of cells despite flattening that increased their areas by over an order of magnitude. We also observed that the earliest synchronized response of cells following the onset of starvation, a precursor to aggregation, was hastened by reducing the thickness of the aqueous culture layer. We were surprised to find that the threshold concentration for aggregation was raised by thin film confinement when compared to bulk behavior. Finally, both the ultra thin and microfluidic preparations reveal, with new clarity, vortex states of aggregation.

Spectral fingerprint of electrostatic forces between biological cells

NASA Astrophysics Data System (ADS)

Murovec, T.; Brosseau, C.

2015-10-01

The prediction of electrostatic forces (EFs) between biological cells still poses challenges of great scientific importance, e.g., cell recognition, electroporation (EP), and mechanosensing. Frequency-domain finite element simulations explore a variety of cell configurations in the range of parameters typical for eukaryotic cells. Here, by applying an electric field to a pair of layered concentric shells, a prototypical model of a biological cell, we provide numerical evidence that the instantaneous EF changes from repulsion to attraction as the drive frequency of the electric field is varied. We identify crossover frequencies and discuss their dependence as a function of field frequency, conductivity of the extracellular medium, and symmetry of the configuration of cells. We present findings which suggest that the spectrum of EFs depends sensitively on the configuration of cells. We discuss the signatures of the collective behavior of systems with many cells in the spectrum of the EF and highlight a few of the observational consequences that this behavior implies. By looking at different cell configurations, we are able to show that the repulsion-to-attraction transition phenomenon is largely associated with an asymmetric electrostatic screening at very small separation between cells. These findings pave the way for the experimental observation of the electromagnetic properties of efficient and simple models of biological tissues.

Human pluripotent stem cells on artificial microenvironments: a high content perspective

PubMed Central

Viswanathan, Priyalakshmi; Gaskell, Terri; Moens, Nathalie; Culley, Oliver J.; Hansen, Darrick; Gervasio, Mia K. R.; Yeap, Yee J.; Danovi, Davide

2014-01-01

Self-renewing stem cell populations are increasingly considered as resources for cell therapy and tools for drug discovery. Human pluripotent stem (hPS) cells in particular offer a virtually unlimited reservoir of homogeneous cells and can be differentiated toward diverse lineages. Many diseases show impairment in self-renewal or differentiation, abnormal lineage choice or other aberrant cell behavior in response to chemical or physical cues. To investigate these responses, there is a growing interest in the development of specific assays using hPS cells, artificial microenvironments and high content analysis. Several hurdles need to be overcome that can be grouped into three areas: (i) availability of robust, homogeneous, and consistent cell populations as a starting point; (ii) appropriate understanding and use of chemical and physical microenvironments; (iii) development of assays that dissect the complexity of cell populations in tissues while mirroring specific aspects of their behavior. Here we review recent progress in the culture of hPS cells and we detail the importance of the environment surrounding the cells with a focus on synthetic material and suitable high content analysis approaches. The technologies described, if properly combined, have the potential to create a paradigm shift in the way diseases are modeled and drug discovery is performed. PMID:25071572

Mouse and human HSPC immobilization in liquid culture by CD43- or CD44-antibody coating.

PubMed

Loeffler, Dirk; Wang, Weijia; Hopf, Alois; Hilsenbeck, Oliver; Bourgine, Paul E; Rudolf, Fabian; Martin, Ivan; Schroeder, Timm

2018-03-29

Keeping track of individual cell identifications is imperative to the study of dynamic single-cell behavior over time. Highly motile hematopoietic stem and progenitor cells (HSPCs) migrate quickly and do not adhere, and thus must be imaged very frequently to keep cell identifications. Even worse, they are also flushed away during medium exchange. To overcome these limitations, we tested antibody coating for reducing HSPC motility in vitro. Anti-CD43- and anti-CD44-antibody coating reduced the cell motility of mouse and human HSPCs in a concentration-dependent manner. This enables 2-dimensional (2D) colony formation without cell mixing in liquid cultures, massively increases time-lapse imaging throughput, and also maintains cell positions during media exchange. Anti-CD43 but not anti-CD44 coating reduces mouse HSPC proliferation with increasing concentrations. No relevant effects on cell survival or myeloid and megakaryocyte differentiation of hematopoietic stem cells and multipotent progenitors 1-5 were detected. Human umbilical cord hematopoietic CD34 + cell survival, proliferation, and differentiation were not affected by either coating. This approach both massively simplifies and accelerates continuous analysis of suspension cells, and enables the study of their behavior in dynamic rather than static culture conditions over time. © 2018 by The American Society of Hematology.

Spectral fingerprint of electrostatic forces between biological cells.

PubMed

Murovec, T; Brosseau, C

2015-10-01

The prediction of electrostatic forces (EFs) between biological cells still poses challenges of great scientific importance, e.g., cell recognition, electroporation (EP), and mechanosensing. Frequency-domain finite element simulations explore a variety of cell configurations in the range of parameters typical for eukaryotic cells. Here, by applying an electric field to a pair of layered concentric shells, a prototypical model of a biological cell, we provide numerical evidence that the instantaneous EF changes from repulsion to attraction as the drive frequency of the electric field is varied. We identify crossover frequencies and discuss their dependence as a function of field frequency, conductivity of the extracellular medium, and symmetry of the configuration of cells. We present findings which suggest that the spectrum of EFs depends sensitively on the configuration of cells. We discuss the signatures of the collective behavior of systems with many cells in the spectrum of the EF and highlight a few of the observational consequences that this behavior implies. By looking at different cell configurations, we are able to show that the repulsion-to-attraction transition phenomenon is largely associated with an asymmetric electrostatic screening at very small separation between cells. These findings pave the way for the experimental observation of the electromagnetic properties of efficient and simple models of biological tissues.

Nuclear DNA Methylation and Chromatin Condensation Phenotypes Are Distinct Between Normally Proliferating/Aging, Rapidly Growing/Immortal, and Senescent Cells

PubMed Central

Gertych, Arkadiusz; Tajbakhsh, Jian

2013-01-01

This study reports on probing the utility of in situ chromatin texture features such as nuclear DNA methylation and chromatin condensation patterns — visualized by fluorescent staining and evaluated by dedicated three-dimensional (3D) quantitative and high-throughput cell-by-cell image analysis — in assessing the proliferative capacity, i.e. growth behavior of cells: to provide a more dynamic picture of a cell population with potential implications in basic science, cancer diagnostics/prognostics and therapeutic drug development. Two types of primary cells and four different cancer cell lines were propagated and subjected to cell-counting, flow cytometry, confocal imaging, and 3D image analysis at various points in culture. Additionally a subset of primary and cancer cells was accelerated into senescence by oxidative stress. DNA methylation and chromatin condensation levels decreased with declining doubling times when primary cells aged in culture with the lowest levels reached at the stage of proliferative senescence. In comparison, immortal cancer cells with constant but higher doubling times mostly displayed lower and constant levels of the two in situ-derived features. However, stress-induced senescent primary and cancer cells showed similar levels of these features compared with primary cells that had reached natural growth arrest. With regards to global DNA methylation and chromatin condensation levels, aggressively growing cancer cells seem to take an intermediate level between normally proliferating and senescent cells. Thus, normal cells apparently reach cancer-cell equivalent stages of the two parameters at some point in aging, which might challenge phenotypic distinction between these two types of cells. Companion high-resolution molecular profiling could provide information on possible underlying differences that would explain benign versus malign cell growth behaviors. PMID:23562889

Nuclear DNA methylation and chromatin condensation phenotypes are distinct between normally proliferating/aging, rapidly growing/immortal, and senescent cells.

PubMed

Oh, Jin Ho; Gertych, Arkadiusz; Tajbakhsh, Jian

2013-03-01

This study reports on probing the utility of in situ chromatin texture features such as nuclear DNA methylation and chromatin condensation patterns - visualized by fluorescent staining and evaluated by dedicated three-dimensional (3D) quantitative and high-throughput cell-by-cell image analysis - in assessing the proliferative capacity, i.e. growth behavior of cells: to provide a more dynamic picture of a cell population with potential implications in basic science, cancer diagnostics/prognostics and therapeutic drug development. Two types of primary cells and four different cancer cell lines were propagated and subjected to cell-counting, flow cytometry, confocal imaging, and 3D image analysis at various points in culture. Additionally a subset of primary and cancer cells was accelerated into senescence by oxidative stress. DNA methylation and chromatin condensation levels decreased with declining doubling times when primary cells aged in culture with the lowest levels reached at the stage of proliferative senescence. In comparison, immortal cancer cells with constant but higher doubling times mostly displayed lower and constant levels of the two in situ-derived features. However, stress-induced senescent primary and cancer cells showed similar levels of these features compared with primary cells that had reached natural growth arrest. With regards to global DNA methylation and chromatin condensation levels, aggressively growing cancer cells seem to take an intermediate level between normally proliferating and senescent cells. Thus, normal cells apparently reach cancer-cell equivalent stages of the two parameters at some point in aging, which might challenge phenotypic distinction between these two types of cells. Companion high-resolution molecular profiling could provide information on possible underlying differences that would explain benign versus malign cell growth behaviors.

Cell-Division Behavior in a Heterogeneous Swarm Environment.

PubMed

Erskine, Adam; Herrmann, J Michael

2015-01-01

We present a system of virtual particles that interact using simple kinetic rules. It is known that heterogeneous mixtures of particles can produce particularly interesting behaviors. Here we present a two-species three-dimensional swarm in which a behavior emerges that resembles cell division. We show that the dividing behavior exists across a narrow but finite band of parameters and for a wide range of population sizes. When executed in a two-dimensional environment the swarm's characteristics and dynamism manifest differently. In further experiments we show that repeated divisions can occur if the system is extended by a biased equilibrium process to control the split of populations. We propose that this repeated division behavior provides a simple model for cell-division mechanisms and is of interest for the formation of morphological structure and to swarm robotics.

Nonlinearity in cytoplasm viscosity can generate an essential symmetry breaking in cellular behaviors.

PubMed

Tachikawa, Masashi; Mochizuki, Atsushi

2015-01-07

The cytoplasms of ameboid cells are nonlinearly viscous. The cell controls this viscosity by modulating the amount, localization and interactions of bio-polymers. Here we investigated how the nonlinearity infers the cellular behaviors and whether nonlinearity-specific behaviors exist. We modeled the developed plasmodium of the slime mold Physarum polycephalum as a network of branching tubes and examined the linear and nonlinear viscous cytoplasm flows in the tubes. We found that the nonlinearity in the cytoplasm׳s viscosity induces a novel type of symmetry breaking in the protoplasmic flow. We also show that symmetry breaking can play an important role in adaptive behaviors, namely, connection of behavioral modes implemented on different time scales and transportation of molecular signals from the front to the rear of the cell during cellular locomotion. Copyright © 2014 Elsevier Ltd. All rights reserved.

A zebrafish embryo behaves both as a "cortical shell-liquid core" structure and a homogeneous solid when experiencing mechanical forces.

PubMed

Liu, Fei; Wu, Dan; Chen, Ken

2014-12-01

Mechanical properties are vital for living cells, and various models have been developed to study the mechanical behavior of cells. However, there is debate regarding whether a cell behaves more similarly to a "cortical shell-liquid core" structure (membrane-like) or a homogeneous solid (cytoskeleton-like) when experiencing stress by mechanical forces. Unlike most experimental methods, which concern the small-strain deformation of a cell, we focused on the mechanical behavior of a cell undergoing small to large strain by conducting microinjection experiments on zebrafish embryo cells. The power law with order of 1.5 between the injection force and the injection distance indicates that the cell behaves as a homogenous solid at small-strain deformation. The linear relation between the rupture force and the microinjector radius suggests that the embryo behaves as membrane-like when subjected to large-strain deformation. We also discuss the possible reasons causing the debate by analyzing the mechanical properties of F-actin filaments.

Optically triggering spatiotemporally confined GPCR activity in a cell and programming neurite initiation and extension

PubMed Central

Karunarathne, W. K. Ajith; Giri, Lopamudra; Kalyanaraman, Vani; Gautam, N.

2013-01-01

G-protein–coupled receptor (GPCR) activity gradients evoke important cell behavior but there is a dearth of methods to induce such asymmetric signaling in a cell. Here we achieved reversible, rapidly switchable patterns of spatiotemporally restricted GPCR activity in a single cell. We recruited properties of nonrhodopsin opsins—rapid deactivation, distinct spectral tuning, and resistance to bleaching—to activate native Gi, Gq, or Gs signaling in selected regions of a cell. Optical inputs were designed to spatiotemporally control levels of second messengers, IP3, phosphatidylinositol (3,4,5)-triphosphate, and cAMP in a cell. Spectrally selective imaging was accomplished to simultaneously monitor optically evoked molecular and cellular response dynamics. We show that localized optical activation of an opsin-based trigger can induce neurite initiation, phosphatidylinositol (3,4,5)-triphosphate increase, and actin remodeling. Serial optical inputs to neurite tips can refashion early neuron differentiation. Methods here can be widely applied to program GPCR-mediated cell behaviors. PMID:23479634

Coordinated dynamic encoding in the retina using opposing forms of plasticity

PubMed Central

Kastner, David B.; Baccus, Stephen A.

2011-01-01

The range of natural inputs encoded by a neuron often exceeds its dynamic range. To overcome this limitation, neural populations divide their inputs among different cell classes, as with rod and cone photoreceptors, and adapt by shifting their dynamic range. We report that the dynamic behavior of retinal ganglion cells in salamanders, mice, and rabbits is divided into two opposing forms of short-term plasticity in different cell classes. One population of cells exhibited sensitization—a persistent elevated sensitivity following a strong stimulus. This novel dynamic behavior compensates for the information loss caused by the known process of adaptation occurring in a separate cell population. The two populations divide the dynamic range of inputs, with sensitizing cells encoding weak signals, and adapting cells encoding strong signals. In the two populations, the linear, threshold and adaptive properties are linked to preserve responsiveness when stimulus statistics change, with one population maintaining the ability to respond when the other fails. PMID:21909086

Migration of cells in a social context

PubMed Central

Vedel, Søren; Tay, Savaş; Johnston, Darius M.; Bruus, Henrik; Quake, Stephen R.

2013-01-01

In multicellular organisms and complex ecosystems, cells migrate in a social context. Whereas this is essential for the basic processes of life, the influence of neighboring cells on the individual remains poorly understood. Previous work on isolated cells has observed a stereotypical migratory behavior characterized by short-time directional persistence with long-time random movement. We discovered a much richer dynamic in the social context, with significant variations in directionality, displacement, and speed, which are all modulated by local cell density. We developed a mathematical model based on the experimentally identified “cellular traffic rules” and basic physics that revealed that these emergent behaviors are caused by the interplay of single-cell properties and intercellular interactions, the latter being dominated by a pseudopod formation bias mediated by secreted chemicals and pseudopod collapse following collisions. The model demonstrates how aspects of complex biology can be explained by simple rules of physics and constitutes a rapid test bed for future studies of collective migration of individual cells. PMID:23251032

Migration of cells in a social context.

PubMed

Vedel, Søren; Tay, Savaş; Johnston, Darius M; Bruus, Henrik; Quake, Stephen R

2013-01-02

In multicellular organisms and complex ecosystems, cells migrate in a social context. Whereas this is essential for the basic processes of life, the influence of neighboring cells on the individual remains poorly understood. Previous work on isolated cells has observed a stereotypical migratory behavior characterized by short-time directional persistence with long-time random movement. We discovered a much richer dynamic in the social context, with significant variations in directionality, displacement, and speed, which are all modulated by local cell density. We developed a mathematical model based on the experimentally identified "cellular traffic rules" and basic physics that revealed that these emergent behaviors are caused by the interplay of single-cell properties and intercellular interactions, the latter being dominated by a pseudopod formation bias mediated by secreted chemicals and pseudopod collapse following collisions. The model demonstrates how aspects of complex biology can be explained by simple rules of physics and constitutes a rapid test bed for future studies of collective migration of individual cells.

Influence of long-term social interaction on chirping behavior, steroid levels and neurogenesis in weakly electric fish

PubMed Central

Dunlap, Kent D.; Chung, Michael; Castellano, James F.

2013-01-01

Summary Social interactions dramatically affect the brain and behavior of animals. Studies in birds and mammals indicate that socially induced changes in adult neurogenesis participate in the regulation of social behavior, but little is known about this relationship in fish. Here, we review studies in electric fish (Apteronotus leptorhychus) that link social stimulation, changes in electrocommunication behavior and adult neurogenesis in brain regions associated with electrocommunication. Compared with isolated fish, fish living in pairs have greater production of chirps, an electrocommunication signal, during dyadic interactions and in response to standardized artificial social stimuli. Social interaction also promotes neurogenesis in the periventricular zone, which contributes born cells to the prepacemaker nucleus, the brain region that regulates chirping. Both long-term chirp rate and periventricular cell addition depend on the signal dynamics (amplitude and waveform variation), modulations (chirps) and novelty of the stimuli from the partner fish. Socially elevated cortisol levels and cortisol binding to glucocorticoid receptors mediate, at least in part, the effect of social interaction on chirping behavior and brain cell addition. In a closely related electric fish (Brachyhypopomus gauderio), social interaction enhances cell proliferation specifically in brain regions for electrocommunication and only during the breeding season, when social signaling is most elaborate. Together, these studies demonstrate a consistent correlation between brain cell addition and environmentally regulated chirping behavior across many social and steroidal treatments and suggest a causal relationship. PMID:23761468

Surface nanoporosity has a greater influence on osteogenic and bacterial cell adhesion than crystallinity and wettability

NASA Astrophysics Data System (ADS)

Rodriguez-Contreras, Alejandra; Guadarrama Bello, Dainelys; Nanci, Antonio

2018-07-01

There has been much emphasis on the influence of crystallinity and wettability for modulating cell activity, particularly for bone biomaterials. In this context, we have generated titanium oxide layers with similar mesoporous topography and surface roughness but with amorphous or crystalline oxide layers and differential wettability. We then investigated their influence on the behavior of MC3T3 osteoblastic and bacterial cells. There was no difference in cell adhesion, spreading and growth on amorphous and crystalline surfaces. The number of focal adhesions was similar, however, cells on the amorphous surface exhibited a higher frequency of mature adhesions. The crystallinity of the surface layers also had no bearing on bacterial adhesion. While it cannot be excluded that surface crystallinity, roughness and wettability contribute to some degree to determining cell behavior, our data suggest that physical characteristics of surfaces represent the major determinant.

Motor characteristics determine the rheological behavior of a suspension of microswimmers

NASA Astrophysics Data System (ADS)

Karmakar, Richa; Gulvady, Ranjit; Tirumkudulu, Mahesh S.; Venkatesh, K. V.

2014-07-01

A suspension of motile cells exhibits complex rheological properties due to their collective motion. We measure the shear viscosity of a suspension of Escherichia coli strains varying in motor characteristics such as duration of run and tumble. At low cell densities, all strains irrespective of their motor characteristics exhibit a linear increase in viscosity with cell density suggesting that the cells behave as a suspension of passive rods with an effective aspect ratio set by the motor characteristics of the bacteria. As the cell density is increased beyond a critical value, the viscosity drops sharply signaling the presence of strongly coordinated motion among bacteria. The critical density depends not only on the magnitude of shear but also the motor characteristics of individual cells. High shear rate disrupts the coordinated motion reducing its behavior, once again, to a suspension of inactive particles.

Cell phone-generated radio frequency electromagnetic field effects on the locomotor behaviors of the fishes Poecilia reticulata and Danio rerio.

PubMed

Lee, David; Lee, Joshua; Lee, Imshik

2015-01-01

The locomotor behavior of small fish was characterized under a cell phone-generated radio frequency electromagnetic field (RF EMF). The trajectory of movement of 10 pairs of guppy (Poecilia reticulate) and 15 pairs of Zebrafish (Danio rerio) in a fish tank was recorded and tracked under the presence of a cell phone-generated RF EMF. The measures were based on spatial and temporal distributions. A time-series trajectory was utilized to emphasize the dynamic nature of locomotor behavior. Fish movement was recorded in real-time. Their spatial, velocity, turning angle and sinuosity distribution were analyzed in terms of F(v,x), P[n(x,t)], P(v), F (θ) and F(s), respectively. In addition, potential temperature elevation caused by a cellular phone was also examined. We demonstrated that a cellular phone-induced temperature elevation was not relevant, and that our measurements reflected RF EMF-induced effects on the locomotor behavior of Poecilia reticulata and Danio rerio. Fish locomotion was observed under normal conditions, in the visual presence of a cell phone, after feeding, and under starvation. Fish locomotor behavior was random both in normal conditions and in the presence of an off-signaled cell phone. However, there were significant changes in the locomotion of the fish after feeding under the RF EMF. The locomotion of the fed fish was affected in terms of changes in population and velocity distributions under the presence of the RF EMF emitted by the cell phone. There was, however, no significant difference in angular distribution.

Brain nuclei in actively courting red-sided garter snakes: a paradigm of neural trimorphism.

PubMed

Krohmer, Randolph W; DeMarchi, Geno A; Baleckaitis, Daniel D; Lutterschmidt, Deborah I; Mason, Robert T

2011-03-28

During the breeding season, two distinct male phenotypes are exhibited by red-sided garter snakes (Thamnophis sirtalis parietalis), with courtship behavior being directed not only toward females, but also toward a sub-population of males called she-males. She-males are morphologically identical to other males except for a circulating androgen level three times that of normal males and their ability to produce a female-like pheromone. As in other vertebrates, limbic nuclei in the red-sided garter snake brain are involved in the control of sexual behaviors. For example, an intact anterior hypothalamus pre-optic area (AHPOA) is essential for the initiation and maintenance of reproduction. To determine if brain morphology varies among the three behavioral phenotypes (i.e., males, she-males, and females) during the breeding season, we examined the volume, cell size and cell density of the AHPOA as well as a control region, the external nucleus of the optic tract (ENOT). We used Luxol Fast Blue and Ziehl's Fuchsin to visualize neurons and glial cells, respectively. No significant differences were observed among the three behavioral phenotypes in the volume, cell size or density in the control region. In contrast, the volume, cell size and density of the AHPOA of she-males were significantly greater than those of both male and female snakes. While the volume of the AHPOA was significantly greater in females compared to males, no differences were observed in cell size or density. These differences in brain morphology suggest a possible underlying mechanism for phenotypic-specific behavioral patterns. Copyright © 2010 Elsevier Inc. All rights reserved.

Dynamically monitoring the gene expression of dual fluorophore in the cell cycle with quantitative spectrum analysis

NASA Astrophysics Data System (ADS)

Lee, Ja-Yun; Wu, Tzong-Yuan; Hsu, I.-Jen

2008-04-01

The cloning and transcription techniques on gene cloned fluorescent proteins have been widely used in many applications. They have been used as reporters of some conditions in a series of reactions. However, it is usually difficult to monitor the specific target with the exactly number of proteins during the process in turbid media, especially at micrometer scales. We successfully revealed an alternative way to monitor the cell cycle behavior and quantitatively analyzed the target cells with green and red fluorescent proteins (GFP and RFP) during different phases of the cell cycle by quantitatively analyzing its behavior and also monitoring its spatial distribution.

Computer modeling of batteries from nonlinear circuit elements

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

Waaben, S.; Dyer, C.K.; Federico, J.

1985-06-01

Circuit analogs for a single battery cell have previously been composed of resistors, capacitors, and inductors. This work introduces a nonlinear circuit model for cell behavior. The circuit is configured around the PIN junction diode, whose charge-storage behavior has features similar to those of electrochemical cells. A user-friendly integrated circuit simulation computer program has reproduced a variety of complex cell responses including electrica isolation effects causing capacity loss, as well as potentiodynamic peaks and discharge phenomena hitherto thought to be thermodynamic in origin. However, in this work, they are shown to be simply due to spatial distribution of stored chargemore » within a practical electrode.« less

Design of Cell-Matrix Interactions in Hyaluronic Acid Hydrogel Scaffolds

PubMed Central

Segura, Tatiana

2013-01-01

The design of hyaluronic acid-based hydrogel scaffolds to elicit highly controlled and tunable cell response and behavior is a major field of interest in developing tissue engineering and regenerative medicine applications. This review will begin with an overview of the biological context of hyaluronic acid, knowledge needed to better understand how to engineer cell-matrix interactions in the scaffolds via the incorporation of different types of signals in order to direct and control cell behavior. Specifically, recent methods of incorporating various bioactive, mechanical, and spatial signals are reviewed, as well as novel hyaluronic acid modifications and crosslinking schemes with a focus on specificity. PMID:23899481

A thermodynamical model for stress-fiber organization in contractile cells.

PubMed

Foucard, Louis; Vernerey, Franck J

2012-01-02

Cell mechanical adaptivity to external stimuli is vital to many of its biological functions. A critical question is therefore to understand the formation and organization of the stress fibers from which emerge the cell's mechanical properties. By accounting for the mechanical aspects and the viscoelastic behavior of stress fibers, we here propose a thermodynamic model to predict the formation and orientation of stress fibers in contractile cells subjected to constant or cyclic stretch and different substrate stiffness. Our results demonstrate that the stress fibers viscoelastic behavior plays a crucial role in their formation and organization and shows good consistency with various experiments.

ELECTRICAL SIGNALING IN CONTROL OF OCULAR CELL BEHAVIORS

PubMed Central

Zhao, Min; Chalmers, Laura; Cao, Lin; Viera, Ana C.; Mannis, Mark; Reid, Brian

2011-01-01

Epithelia of the cornea, lens and retina contain a vast array of ion channels and pumps. Together they produce a polarized flow of ions in and out of cells, as well as across the epithelia. These naturally occurring ion fluxes are essential to the hydration and metabolism of the ocular tissues, especially for the avascular cornea and lens. The directional transport of ions generates electric fields and currents in those tissues. Applied electric fields affect migration, division and proliferation of ocular cells which are important in homeostasis and healing of the ocular tissues. Abnormalities in any of those aspects may underlie many ocular diseases, for example chronic corneal ulcers, posterior capsule opacity after cataract surgery, and retinopathies. Electric field-inducing cellular responses, termed electrical signaling here, therefore may be an unexpected yet powerful mechanism in regulating ocular cell behavior. Both endogenous electric fields and applied electric fields could be exploited to regulate ocular cells. We aim to briefly describe the physiology of the naturally occurring electrical activities in the corneal, lens, and retinal epithelia, to provide experimental evidence of the effects of electric fields on ocular cell behaviors, and to suggest possible clinical implications. PMID:22020127

Emphasizing the role of surface chemistry on hydrophobicity and cell adhesion behavior of polydimethylsiloxane/TiO2 nanocomposite films.

PubMed

Yousefi, Seyedeh Zahra; Tabatabaei-Panah, Pardis-Sadat; Seyfi, Javad

2018-07-01

Improving the bioinertness of materials is of great importance for developing biomedical devices that contact human tissues. The main goal of this study was to establish correlations among surface morphology, roughness and chemistry with hydrophobicity and cell adhesion in polydimethylsiloxane (PDMS) nanocomposites loaded with titanium dioxide (TiO 2 ) nanoparticles. Firstly, wettability results showed that the nanocomposite loaded with 30 wt.% of TiO 2 exhibited a superhydrophobic behavior; however, the morphology and roughness analysis proved that there was no discernible difference between the surface structures of samples loaded with 20 and 30 wt.% of nanoparticles. Both cell culture and MTT assay experiments showed that, despite the similarity between the surface structures, the sample loaded with 30 wt.% nanoparticles exhibits the greatest reduction in the cell viability (80%) as compared with the pure PDMS film. According to the X-ray photoelectron spectroscopy results, the remarkable reduction in cell viability of the superhydrophobic sample could be majorly attributed to the role of surface chemistry. The obtained results emphasize the importance of adjusting the surface properties especially surface chemistry to gain the optimum cell adhesion behavior. Copyright © 2018 Elsevier B.V. All rights reserved.

Six different roles for crossover inhibition in the retina: correcting the nonlinearities of synaptic transmission.

PubMed

Werblin, Frank S

2010-03-01

Early retinal studies categorized ganglion cell behavior as either linear or nonlinear and rectifying as represented by the familiar X- and Y-type ganglion cells in cat. Nonlinear behavior is in large part a consequence of the rectifying nonlinearities inherent in synaptic transmission. These nonlinear signals underlie many special functions in retinal processing, including motion detection, motion in motion, and local edge detection. But linear behavior is also required for some visual processing tasks. For these tasks, the inherently nonlinear signals are "linearized" by "crossover inhibition." Linearization utilizes a circuitry whereby nonlinear ON inhibition adds with nonlinear OFF excitation or ON excitation adds with OFF inhibition to generate a more linear postsynaptic voltage response. Crossover inhibition has now been measured in most bipolar, amacrine, and ganglion cells. Functionally crossover inhibition enhances edge detection, allows ganglion cells to recognize luminance-neutral patterns with their receptive fields, permits ganglion cells to distinguish contrast from luminance, and maintains a more constant conductance during the light response. In some cases, crossover extends the operating range of cone-driven OFF ganglion cells into the scotopic levels. Crossover inhibition is also found in neurons of the lateral geniculate nucleus and V1.

In Vivo Analysis of Alternative Modes of Breast Cancer Cell Invasion

DTIC Science & Technology

2009-05-01

lapse videomicroscopy . Bright field time-lapse videomicroscopy revealed that the MMTV-neu cells moved as both round ed and e longated cells on a...behavior. Working with 3-D gel s and time-lapse videomicroscopy I hav e also gained an apprec iation of the way in which mammary tumor cells

The development and geometry of shape change in Arabidopsis thaliana cotyledon pavement cells

PubMed Central

2011-01-01

Background The leaf epidermis is an important architectural control element that influences the growth properties of underlying tissues and the overall form of the organ. In dicots, interdigitated pavement cells are the building blocks of the tissue, and their morphogenesis includes the assembly of specialized cell walls that surround the apical, basal, and lateral (anticlinal) cell surfaces. The microtubule and actin cytoskeletons are highly polarized along the cortex of the anticlinal wall; however, the relationships between these arrays and cell morphogenesis are unclear. Results We developed new quantitative tools to compare population-level growth statistics with time-lapse imaging of cotyledon pavement cells in an intact tissue. The analysis revealed alternating waves of lobe initiation and a phase of lateral isotropic expansion that persisted for days. During lateral isotropic diffuse growth, microtubule organization varied greatly between cell surfaces. Parallel microtubule bundles were distributed unevenly along the anticlinal surface, with subsets marking stable cortical domains at cell indentations and others clearly populating the cortex within convex cell protrusions. Conclusions Pavement cell morphogenesis is discontinuous, and includes punctuated phases of lobe initiation and lateral isotropic expansion. In the epidermis, lateral isotropic growth is independent of pavement cell size and shape. Cortical microtubules along the upper cell surface and stable cortical patches of anticlinal microtubules may coordinate the growth behaviors of orthogonal cell walls. This work illustrates the importance of directly linking protein localization data to the growth behavior of leaf epidermal cells. PMID:21284861

The development and geometry of shape change in Arabidopsis thaliana cotyledon pavement cells.

PubMed

Zhang, Chunhua; Halsey, Leah E; Szymanski, Daniel B

2011-02-01

The leaf epidermis is an important architectural control element that influences the growth properties of underlying tissues and the overall form of the organ. In dicots, interdigitated pavement cells are the building blocks of the tissue, and their morphogenesis includes the assembly of specialized cell walls that surround the apical, basal, and lateral (anticlinal) cell surfaces. The microtubule and actin cytoskeletons are highly polarized along the cortex of the anticlinal wall; however, the relationships between these arrays and cell morphogenesis are unclear. We developed new quantitative tools to compare population-level growth statistics with time-lapse imaging of cotyledon pavement cells in an intact tissue. The analysis revealed alternating waves of lobe initiation and a phase of lateral isotropic expansion that persisted for days. During lateral isotropic diffuse growth, microtubule organization varied greatly between cell surfaces. Parallel microtubule bundles were distributed unevenly along the anticlinal surface, with subsets marking stable cortical domains at cell indentations and others clearly populating the cortex within convex cell protrusions. Pavement cell morphogenesis is discontinuous, and includes punctuated phases of lobe initiation and lateral isotropic expansion. In the epidermis, lateral isotropic growth is independent of pavement cell size and shape. Cortical microtubules along the upper cell surface and stable cortical patches of anticlinal microtubules may coordinate the growth behaviors of orthogonal cell walls. This work illustrates the importance of directly linking protein localization data to the growth behavior of leaf epidermal cells.

Impact of Simulated Microgravity on Cytoskeleton and Viscoelastic Properties of Endothelial Cell

NASA Astrophysics Data System (ADS)

Janmaleki, M.; Pachenari, M.; Seyedpour, S. M.; Shahghadami, R.; Sanati-Nezhad, A.

2016-09-01

This study focused on the effects of simulated microgravity (s-μg) on mechanical properties, major cytoskeleton biopolymers, and morphology of endothelial cells (ECs). The structural and functional integrity of ECs are vital to regulate vascular homeostasis and prevent atherosclerosis. Furthermore, these highly gravity sensitive cells play a key role in pathogenesis of many diseases. In this research, impacts of s-μg on mechanical behavior of human umbilical vein endothelial cells were investigated by utilizing a three-dimensional random positioning machine (3D-RPM). Results revealed a considerable drop in cell stiffness and viscosity after 24 hrs of being subjected to weightlessness. Cortical rigidity experienced relatively immediate and significant decline comparing to the stiffness of whole cell body. The cells became rounded in morphology while western blot analysis showed reduction of the main cytoskeletal components. Moreover, fluorescence staining confirmed disorganization of both actin filaments and microtubules (MTs). The results were compared statistically among test and control groups and it was concluded that s-μg led to a significant alteration in mechanical behavior of ECs due to remodeling of cell cytoskeleton.

Spatial distribution of filament elasticity determines the migratory behaviors of a cell

PubMed Central

Harn, Hans I-Chen; Hsu, Chao-Kai; Wang, Yang-Kao; Huang, Yi-Wei; Chiu, Wen-Tai; Lin, Hsi-Hui; Cheng, Chao-Min; Tang, Ming-Jer

2016-01-01

ABSTRACT Any cellular response leading to morphological changes is highly tuned to balance the force generated from structural reorganization, provided by actin cytoskeleton. Actin filaments serve as the backbone of intracellular force, and transduce external mechanical signal via focal adhesion complex into the cell. During migration, cells not only undergo molecular changes but also rapid mechanical modulation. Here we focus on determining, the role of spatial distribution of mechanical changes of actin filaments in epithelial, mesenchymal, fibrotic and cancer cells with non-migration, directional migration, and non-directional migration behaviors using the atomic force microscopy. We found 1) non-migratory cells only generated one type of filament elasticity, 2) cells generating spatially distributed two types of filament elasticity showed directional migration, and 3) pathologic cells that autonomously generated two types of filament elasticity without spatial distribution were actively migrating non-directionally. The demonstration of spatial regulation of filament elasticity of different cell types at the nano-scale highlights the coupling of cytoskeletal function with physical characters at the sub-cellular level, and provides new research directions for migration related disease. PMID:26919488

Multi-Node Thermal System Model for Lithium-Ion Battery Packs: Preprint

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

Shi, Ying; Smith, Kandler; Wood, Eric

Temperature is one of the main factors that controls the degradation in lithium ion batteries. Accurate knowledge and control of cell temperatures in a pack helps the battery management system (BMS) to maximize cell utilization and ensure pack safety and service life. In a pack with arrays of cells, a cells temperature is not only affected by its own thermal characteristics but also by its neighbors, the cooling system and pack configuration, which increase the noise level and the complexity of cell temperatures prediction. This work proposes to model lithium ion packs thermal behavior using a multi-node thermal network model,more » which predicts the cell temperatures by zones. The model was parametrized and validated using commercial lithium-ion battery packs. neighbors, the cooling system and pack configuration, which increase the noise level and the complexity of cell temperatures prediction. This work proposes to model lithium ion packs thermal behavior using a multi-node thermal network model, which predicts the cell temperatures by zones. The model was parametrized and validated using commercial lithium-ion battery packs.« less

Imparting magnetic dipole heterogeneity to internalized iron oxide nanoparticles for microorganism swarm control

NASA Astrophysics Data System (ADS)

Kim, Paul Seung Soo; Becker, Aaron; Ou, Yan; Julius, Anak Agung; Kim, Min Jun

2015-03-01

Tetrahymena pyriformis is a single cell eukaryote that can be modified to respond to magnetic fields, a response called magnetotaxis. Naturally, this microorganism cannot respond to magnetic fields, but after modification using iron oxide nanoparticles, cells are magnetized and exhibit a constant magnetic dipole strength. In experiments, a rotating field is applied to cells using a two-dimensional approximate Helmholtz coil system. Using rotating magnetic fields, we characterize discrete cells' swarm swimming which is affected by several factors. The behavior of the cells under these fields is explained in detail. After the field is removed, relatively straight swimming is observed. We also generate increased heterogeneity within a population of cells to improve controllability of a swarm, which is explored in a cell model. By exploiting this straight swimming behavior, we propose a method to control discrete cells utilizing a single global magnetic input. Successful implementation of this swarm control method would enable teams of microrobots to perform a variety of in vitro microscale tasks impossible for single microrobots, such as pushing objects or simultaneous micromanipulation of discrete entities.

The effects of lithium counterdoping on radiation damage and annealing in n(+)p silicon solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Brandhorst, H. W., Jr.; Mehta, S.; Swartz, C. K.

1984-01-01

Boron-doped silicon n(+)p solar cells were counterdoped with lithium by ion implantation and the resultant n(+)p cells irradiated by 1 MeV electrons. Performance parameters were determined as a function of fluence and a deep level transient spectroscopy (DLTS) study was conducted. The lithium counterdoped cells exhibited significantly increased radiation resistance when compared to boron doped control cells. Isochronal annealing studies of cell performance indicate that significant annealing occurs at 100 C. Isochronal annealing of the deep level defects showed a correlation between a single defect at E sub v + 0.43 eV and the annealing behavior of short circuit current in the counterdoped cells. The annealing behavior was controlled by dissociation and recombination of this defect. The DLTS studies showed that counterdoping with lithium eliminated three deep level defects and resulted in three new defects. The increased radiation resistance of the counterdoped cells is due to the interaction of lithium with oxygen, single vacancies and divacancies. The lithium-oxygen interaction is the most effective in contributing to the increased radiation resistance.

Response of MG63 osteoblast-like cells onto polycarbonate membrane surfaces with different micropore sizes.

PubMed

Lee, Sang Jin; Choi, Jin San; Park, Ki Suk; Khang, Gilson; Lee, Young Moo; Lee, Hai Bang

2004-08-01

Response of different types of cells on materials is important for the applications of tissue engineering and regenerative medicine. It is recognized that the behavior of the cell adhesion, proliferation, and differentiation on materials depends largely on surface characteristics such as wettability, chemistry, charge, rigidity, and roughness. In this study, we examined the behavior of MG63 osteoblast-like cells cultured on a polycarbonate (PC) membrane surfaces with different micropore sizes (0.2-8.0 microm in diameter). Cell adhesion and proliferation to the PC membrane surfaces were determined by cell counting and MTT assay. The effect of surface micropore on the MG63 cells was evaluated by cell morphology, protein content, and alkaline phosphatase (ALP) specific activity. It seems that the cell adhesion and proliferation were progressively inhibited as the PC membranes had micropores with increasing size, probably due to surface discontinuities produced by track-etched pores. Increasing micropore size of the PC membrane results in improved protein synthesis and ALP specific activity in isolated cells. There was a statistically significant difference (P<0.05) between different micropore sizes. The MG63 cells also maintained their phenotype under conditions that support a round cell shape. RT-PCR analysis further confirmed the osteogenic phenotype of the MG63 cells onto the PC membranes with different micropore sizes. In results, as micropore size is getting larger, cell number is reduced and cell differentiation and matrix production is increased. This study demonstrated that the surface topography plays an important role for phenotypic expression of the MG63 osteoblast-like cells.

Cellular automata model for human articular chondrocytes migration, proliferation and cell death: An in vitro validation.

PubMed

Vaca-González, J J; Gutiérrez, M L; Guevara, J M; Garzón-Alvarado, D A

2017-01-01

Articular cartilage is characterized by low cell density of only one cell type, chondrocytes, and has limited self-healing properties. When articular cartilage is affected by traumatic injuries, a therapeutic strategy such as autologous chondrocyte implantation is usually proposed for its treatment. This approach requires in vitro chondrocyte expansion to yield high cell number for cell transplantation. To improve the efficiency of this procedure, it is necessary to assess cell dynamics such as migration, proliferation and cell death during culture. Computational models such as cellular automata can be used to simulate cell dynamics in order to enhance the result of cell culture procedures. This methodology has been implemented for several cell types; however, an experimental validation is required for each one. For this reason, in this research a cellular automata model, based on random-walk theory, was devised in order to predict articular chondrocyte behavior in monolayer culture during cell expansion. Results demonstrated that the cellular automata model corresponded to cell dynamics and computed-accurate quantitative results. Moreover, it was possible to observe that cell dynamics depend on weighted probabilities derived from experimental data and cell behavior varies according to the cell culture period. Thus, depending on whether cells were just seeded or proliferated exponentially, culture time probabilities differed in percentages in the CA model. Furthermore, in the experimental assessment a decreased chondrocyte proliferation was observed along with increased passage number. This approach is expected to having other uses as in enhancing articular cartilage therapies based on tissue engineering and regenerative medicine.

Universal behavior of the osmotically compressed cell and its analogy to the colloidal glass transition

PubMed Central

Zhou, E. H.; Trepat, X.; Park, C. Y.; Lenormand, G.; Oliver, M. N.; Mijailovich, S. M.; Hardin, C.; Weitz, D. A.; Butler, J. P.; Fredberg, J. J.

2009-01-01

Mechanical robustness of the cell under different modes of stress and deformation is essential to its survival and function. Under tension, mechanical rigidity is provided by the cytoskeletal network; with increasing stress, this network stiffens, providing increased resistance to deformation. However, a cell must also resist compression, which will inevitably occur whenever cell volume is decreased during such biologically important processes as anhydrobiosis and apoptosis. Under compression, individual filaments can buckle, thereby reducing the stiffness and weakening the cytoskeletal network. However, the intracellular space is crowded with macromolecules and organelles that can resist compression. A simple picture describing their behavior is that of colloidal particles; colloids exhibit a sharp increase in viscosity with increasing volume fraction, ultimately undergoing a glass transition and becoming a solid. We investigate the consequences of these 2 competing effects and show that as a cell is compressed by hyperosmotic stress it becomes progressively more rigid. Although this stiffening behavior depends somewhat on cell type, starting conditions, molecular motors, and cytoskeletal contributions, its dependence on solid volume fraction is exponential in every instance. This universal behavior suggests that compression-induced weakening of the network is overwhelmed by crowding-induced stiffening of the cytoplasm. We also show that compression dramatically slows intracellular relaxation processes. The increase in stiffness, combined with the slowing of relaxation processes, is reminiscent of a glass transition of colloidal suspensions, but only when comprised of deformable particles. Our work provides a means to probe the physical nature of the cytoplasm under compression, and leads to results that are universal across cell type. PMID:19520830

Dermal regulatory T cells display distinct migratory behavior that is modulated during adaptive and innate inflammation.

PubMed

Chow, Zachary; Mueller, Scott N; Deane, James A; Hickey, Michael J

2013-09-15

Regulatory T cells (Tregs) are important in controlling skin inflammation, an effect dependent on their ability to home to this organ. However, little is known regarding their behavior in the skin. In this study, we used multiphoton imaging in Foxp3-GFP mice to examine the behavior of endogenous Tregs in resting and inflamed skin. Although Tregs were readily detectable in the uninflamed dermis, most were nonmotile. Induction of contact sensitivity increased the proportion of motile Tregs, and also induced Treg recruitment. This response was significantly blunted in mice challenged with an irrelevant hapten, or by inhibition of effector cell recruitment, indicating a role for T cell-dependent inflammation in induction of Treg migration. Moreover, induction of Treg migration was inhibited by local injection of a CCR4 antagonist, indicating a role for CCR4 in this response. Exposure of naive mice to hapten also induced an increase in the proportion of migratory Tregs, demonstrating that innate signals can also induce Treg migration. Simultaneous examination of the migration of CD4⁺ effector cells and Tregs in the same region of uninflamed skin demonstrated that effector cells behaved differently, being uniformly highly migratory. These findings indicate that Treg behavior in skin differs from that of CD4⁺ effector cells, in that only a low proportion of Tregs is migratory under resting conditions. However, in response to both adaptive and innate inflammation, the proportion of migratory Tregs increases, raising the possibility that this response is important in multiple forms of skin inflammation.

A Novel Ex Vivo Method for Visualizing Live-Cell Calcium Response Behavior in Intact Human Tumors.

PubMed

Koh, James; Hogue, Joyce A; Sosa, Julie A

2016-01-01

The functional impact of intratumoral heterogeneity has been difficult to assess in the absence of a means to interrogate dynamic, live-cell biochemical events in the native tissue context of a human tumor. Conventional histological methods can reveal morphology and static biomarker expression patterns but do not provide a means to probe and evaluate tumor functional behavior and live-cell responsiveness to experimentally controlled stimuli. Here, we describe an approach that couples vibratome-mediated viable tissue sectioning with live-cell confocal microscopy imaging to visualize human parathyroid adenoma tumor cell responsiveness to extracellular calcium challenge. Tumor sections prepared as 300 micron-thick tissue slices retain viability throughout a >24 hour observation period and retain the native architecture of the parental tumor. Live-cell observation of biochemical signaling in response to extracellular calcium challenge in the intact tissue slices reveals discrete, heterogeneous kinetic waveform categories of calcium agonist reactivity within each tumor. Plotting the proportion of maximally responsive tumor cells as a function of calcium concentration yields a sigmoid dose-response curve with a calculated calcium EC50 value significantly elevated above published reference values for wild-type calcium-sensing receptor (CASR) sensitivity. Subsequent fixation and immunofluorescence analysis of the functionally evaluated tissue specimens allows alignment and mapping of the physical characteristics of individual cells within the tumor to specific calcium response behaviors. Evaluation of the relative abundance of intracellular PTH in tissue slices challenged with variable calcium concentrations demonstrates that production of the hormone can be dynamically manipulated ex vivo. The capability of visualizing live human tumor tissue behavior in response to experimentally controlled conditions opens a wide range of possibilities for personalized ex vivo therapeutic testing. This highly adaptable system provides a unique platform for live-cell ex vivo provocative testing of human tumor responsiveness to a range of physiological agonists or candidate therapeutic compounds.

The phenotype of cancer cell invasion controlled by fibril diameter and pore size of 3D collagen networks.

PubMed

Sapudom, Jiranuwat; Rubner, Stefan; Martin, Steve; Kurth, Tony; Riedel, Stefanie; Mierke, Claudia T; Pompe, Tilo

2015-06-01

The behavior of cancer cells is strongly influenced by the properties of extracellular microenvironments, including topology, mechanics and composition. As topological and mechanical properties of the extracellular matrix are hard to access and control for in-depth studies of underlying mechanisms in vivo, defined biomimetic in vitro models are needed. Herein we show, how pore size and fibril diameter of collagen I networks distinctively regulate cancer cell morphology and invasion. Three-dimensional collagen I matrices with a tight control of pore size, fibril diameter and stiffness were reconstituted by adjustment of concentration and pH value during matrix reconstitution. At first, a detailed analysis of topology and mechanics of matrices using confocal laser scanning microscopy, image analysis tools and force spectroscopy indicate pore size and not fibril diameter as the major determinant of matrix elasticity. Secondly, by using two different breast cancer cell lines (MDA-MB-231 and MCF-7), we demonstrate collagen fibril diameter--and not pore size--to primarily regulate cell morphology, cluster formation and invasion. Invasiveness increased and clustering decreased with increasing fibril diameter for both, the highly invasive MDA-MB-231 cells with mesenchymal migratory phenotype and the MCF-7 cells with amoeboid migratory phenotype. As this behavior was independent of overall pore size, matrix elasticity is shown to be not the major determinant of the cell characteristics. Our work emphasizes the complex relationship between structural-mechanical properties of the extracellular matrix and invasive behavior of cancer cells. It suggests a correlation of migratory and invasive phenotype of cancer cells in dependence on topological and mechanical features of the length scale of single fibrils and not on coarse-grained network properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Survival features of EBV-stabilized cells from centenarians: morpho-functional and transcriptomic analyses.

PubMed

Matarrese, Paola; Tinari, Antonella; Ascione, Barbara; Gambardella, Lucrezia; Remondini, Daniel; Salvioli, Stefano; Tenedini, Elena; Tagliafico, Enrico; Franceschi, Claudio; Malorni, Walter

2012-12-01

In the present work, we analyzed the survival features of six different Epstein-Barr virus (EBV)-stabilized lymphoid cell lines obtained from adult subjects and from subjects of more than 95 years. For the first, we found that lymphoid B cells from centenarians were more resistant to apoptosis induction and displayed a more developed lysosomal compartment, the most critical component of phagic machinery, in comparison with lymphoid B cells from adult subjects. In addition, cells from centenarians were capable of engulfing and digesting other cells, i.e., their siblings (even entire cells), whereas lymphoid cells from "control samples", i.e., from adults, did not. This behavior was improved by nutrient deprivation but, strikingly, it was unaffected by the autophagy-modulating drug, rapamycin, an autophagy inducer, and 3-methyladenine, an autophagy inhibitor. Transcriptomic analyses indicated that: (1) aspartyl proteases, (2) cell surface molecules such as integrins and cadherins, and (3) some components of cytoskeletal network could contribute to establish this survival phenotype. Also, Kyoto Encyclopedia of Genes and Genomes pathways such as Wnt signaling pathway, an essential contributor to cell migration and actin cytoskeleton remodeling, appeared as prominent. Although we cannot rule out the possibility that EBV-immortalization could play a role, since we observed this phagic behavior in cells from centenarians but not in those from adults, we hypothesize that it may represent an important survival determinant in cells from centenarians.

Students' Use of Cell Phones in Class for Off-Task Behaviors: The Indirect Impact of Instructors' Teaching Behaviors through Boredom and Students' Attitudes

ERIC Educational Resources Information Center

Bolkan, San; Griffin, Darrin J.

2017-01-01

This study was conducted to determine how various teaching behaviors influence students' emotional and cognitive experiences in class, and how these experiences relate to students' use of cell phones while considering contextual factors that might influence this outcome. Two hundred and seventy-four students responded to questions regarding their…

Yeast G-proteins mediate directional sensing and polarization behaviors in response to changes in pheromone gradient direction

PubMed Central

Moore, Travis I.; Tanaka, Hiromasa; Kim, Hyung Joon; Jeon, Noo Li; Yi, Tau-Mu

2013-01-01

Yeast cells polarize by projecting up mating pheromone gradients, a classic cell polarity behavior. However, these chemical gradients may shift direction. We examine how yeast cells sense and respond to a 180o switch in the direction of microfluidically generated pheromone gradients. We identify two behaviors: at low concentrations of α-factor, the initial projection grows by bending, whereas at high concentrations, cells form a second projection toward the new source. Mutations that increase heterotrimeric G-protein activity expand the bending-growth morphology to high concentrations; mutations that increase Cdc42 activity result in second projections at low concentrations. Gradient-sensing projection bending requires interaction between Gβγ and Cdc24, whereas gradient-nonsensing projection extension is stimulated by Bem1 and hyperactivated Cdc42. Of interest, a mutation in Gα affects both bending and extension. Finally, we find a genetic perturbation that exhibits both behaviors. Overexpression of the formin Bni1, a component of the polarisome, makes both bending-growth projections and second projections at low and high α-factor concentrations, suggesting a role for Bni1 downstream of the heterotrimeric G-protein and Cdc42 during gradient sensing and response. Thus we demonstrate that G-proteins modulate in a ligand-dependent manner two fundamental cell-polarity behaviors in response to gradient directional change. PMID:23242998

Titanium is not "the most biocompatible metal" under cathodic potential: The relationship between voltage and MC3T3 preosteoblast behavior on electrically polarized cpTi surfaces.

PubMed

Ehrensberger, Mark T; Sivan, Shiril; Gilbert, Jeremy L

2010-06-15

An electrochemically controlled system has been developed which allows for cell culture directly on electrically polarized metal surfaces with simultaneous control and assessment of the electrochemical current, potential, and impedance of the interface. This system was utilized in this study to assess the interactions between electrochemically polarized commercially pure titanium (cpTi) and MC3T3 preosteoblast cells. Cells were cultured on CpTi for 24 h at static potentials between -1000 mV and +1000 mV vs. Ag/AgCl and cell morphology (SEM and cell area) and viability (MTT and Live-Dead assay) were assessed along with the electrochemical current densities and surface oxide impedance properties. The results indicate that cathodic polarization in the range of -600 mV to -1000 mV markedly reduces the spreading and viability of cells cultured directly on cpTi within 24 h, while anodic polarization (-300 mV to +1000 mV) out to 72 h shows no difference in cell behavior as compared to the OCP condition. Analysis of the relationship between the cell outcomes and the electrochemical current densities and impedance indicated the presence of voltage-dependent electrochemical thresholds (cathodic current density, i(c) > 1.0 microA/cm(2), R(p) < 10(5) Omega cm(2)) which may control the biocompatibility of cpTi. In addition, these outcomes have direct clinical significance for modular orthopedic implants whose potential can shift, via fretting corrosion, down into the range of potentials exhibiting poor cell behavior. (c) 2009 Wiley Periodicals, Inc.

Silencing of long non-coding RNA CCAT2 depressed malignancy of oral squamous cell carcinoma via Wnt/β-catenin pathway.

PubMed

Ma, Yuji; Hu, Xuanhao; Shang, Chao; Zhong, Ming; Guo, Yan

2017-07-01

Oral squamous cell carcinoma is a common and lethal malignancy affecting the head and neck region. CCAT2 (colon cancer-associated transcript 2) gene is affiliated with long non-coding RNAs, which are often found to have important regulatory roles in cancers. This study aims to assess the expression and clinical significance of CCAT2 gene, identify its malignant biological behaviors, and explore the possible mechanisms in oral squamous cell carcinoma. CCAT2 expression was detected by quantitative real-time polymerase chain reaction, and its relationship with clinical factors was assayed using the Kaplan-Meier survival curve. The biological behaviors of CCAT2 and its potential mechanisms in oral squamous cell carcinoma were explored by the combined use of CCAT2 knockdown technology and the Wnt/β-catenin pathway agonist lithium chloride (LiCl). Our results showed that CCAT2 functioning as a potential oncogene was upregulated in oral squamous cell carcinoma. CCAT2 with high expression level was correlated with poor differentiation, higher T stage, and clinical stage, which made CCAT2 to be a prognostic biomarker in oral squamous cell carcinoma. LiCl-activated Wnt/β-catenin signaling pathway could partly restore the CCAT2-mediated malignant biological behaviors of oral squamous cell carcinoma cells by suppressing β-catenin, CCND1, and MYC and activating glycogen synthase kinase 3 beta expression. These findings might assist in the discovery of novel potential diagnostic and therapeutic target for oral squamous cell carcinoma, thereby improve the effects of clinical treatment in patients.

Microfluidic chip integrated with flexible PDMS-based electrochemical cytosensor for dynamic analysis of drug-induced apoptosis on HeLa cells.

PubMed

Cao, Jun-Tao; Zhu, Ying-Di; Rana, Rohit Kumar; Zhu, Jun-Jie

2014-01-15

A novel microfluidic platform integrated with a flexible PDMS-based electrochemical cytosensor was developed for real-time monitoring of the proliferation and apoptosis of HeLa cells. The PDMS-gold film, which had a conductive smooth surface and was semi-transparent, facilitated electrochemical measurements and optical microscope observations. We observed distinct increases and decreases in peak current intensity, corresponding to cell proliferation in culture medium and apoptosis in the presence of an anticancer drug, respectively. This electrochemical analysis method permitted real-time, label-free monitoring of cell behavior, and the electrochemical results were confirmed with optical microscopy. The flexible microfluidic electrochemical platform presented here is suitable for on-site monitoring of cell behavior in microenvironments. © 2013 Elsevier B.V. All rights reserved.

Vertically, interconnected carbon nanowalls as biocompatible scaffolds for osteoblast cells

NASA Astrophysics Data System (ADS)

Ion, Raluca; Vizireanu, Sorin; Luculescu, Catalin; Cimpean, Anisoara; Dinescu, Gheorghe

2016-07-01

The response of MC3T3-E1 pre-osteoblasts to vertically aligned, interconnected carbon nanowalls prepared by plasma enhanced chemical vapor deposition on silicon substrate has been evaluated in terms of cell adhesion, viability and cell proliferation. The behavior of osteoblasts seeded on carbon nanowalls was analyzed in parallel and compared with the behavior of the cells maintained in contact with tissue culture polystyrene (TCPS). The results demonstrate that osteoblasts adhere and remain viable in the long term on carbon nanowalls. Moreover, on the investigated scaffold cell proliferation was significantly promoted, although to a lower extent than on TCPS. Overall, the successful culture of osteoblasts on carbon nanowalls coated substrate confirms the biocompatibility of this scaffold, which could have potential applications in the development of orthopedic biomaterials.

Prestressed F-actin networks cross-linked by hinged filamins replicate mechanical properties of cells

NASA Astrophysics Data System (ADS)

Gardel, M. L.; Nakamura, F.; Hartwig, J. H.; Crocker, J. C.; Stossel, T. P.; Weitz, D. A.

2006-02-01

We show that actin filaments, shortened to physiological lengths by gelsolin and cross-linked with recombinant human filamins (FLNs), exhibit dynamic elastic properties similar to those reported for live cells. To achieve elasticity values of comparable magnitude to those of cells, the in vitro network must be subjected to external prestress, which directly controls network elasticity. A molecular requirement for the strain-related behavior at physiological conditionsis a flexible hinge found in FLNa and some FLNb molecules. Basic physical properties of the in vitro filamin-F-actin network replicate the essential mechanical properties of living cells. This physical behavior could accommodate passive deformation and internal organelle trafficking at low strains yet resist externally or internally generated high shear forces. cytoskeleton | cell mechanics | nonlinear rheology

Drift and Behavior of E. coli Cells

NASA Astrophysics Data System (ADS)

Micali, Gabriele; Colin, Rémy; Sourjik, Victor; Endres, Robert G.

2017-12-01

Chemotaxis of the bacterium Escherichia coli is well understood in shallow chemical gradients, but its swimming behavior remains difficult to interpret in steep gradients. By focusing on single-cell trajectories from simulations, we investigated the dependence of the chemotactic drift velocity on attractant concentration in an exponential gradient. While maxima of the average drift velocity can be interpreted within analytical linear-response theory of chemotaxis in shallow gradients, limits in drift due to steep gradients and finite number of receptor-methylation sites for adaptation go beyond perturbation theory. For instance, we found a surprising pinning of the cells to the concentration in the gradient at which cells run out of methylation sites. To validate the positions of maximal drift, we recorded single-cell trajectories in carefully designed chemical gradients using microfluidics.

Organization of the Drosophila circadian control circuit.

PubMed

Nitabach, Michael N; Taghert, Paul H

2008-01-22

Molecular genetics has revealed the identities of several components of the fundamental circadian molecular oscillator - an evolutionarily conserved molecular mechanism of transcription and translation that can operate in a cell-autonomous manner. Therefore, it was surprising when studies of circadian rhythmic behavior in the fruit fly Drosophila suggested that the normal operations of circadian clock cells, which house the molecular oscillator, in fact depend on non-cell-autonomous effects - interactions between the clock cells themselves. Here we review several genetic analyses that broadly extend that viewpoint. They support a model whereby the approximately 150 circadian clock cells in the brain of the fly are sub-divided into functionally discrete rhythmic centers. These centers alternatively cooperate or compete to control the different episodes of rhythmic behavior that define the fly's daily activity profile.

Mucilage processing and secretion in the green alga closterium. I. Cytology and biochemistry

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

Domozych, C.R.; Plante, K.; Blais, P.

1993-10-01

Placoderm desmids (Conjugales, Chlorophyta) such as Closterium exhibit a gliding locomotory behavior. This results from the forceful extrusion of an acidic polysaccharide from one pole of the cell causing the cell to glide in the opposite direction. A biochemical and cytological analysis of gliding behavior was performed. The mucilage is a high molecular weight polysaccharide rich in glucuronic acid and fucose. Under normal growth conditions, 3 [mu]g of mucilage is produced per cell in 30 days. Mucilage production increased 3-4 fold in cells challenged with low phosphate or nitrate conditions. A polyclonal antibody was raised against the mucilage and usedmore » in immunofluorescence studies. These results show that upon contact with another object Closterium aligns itself parallel to that object by a [open quotes]jack-knife[close quotes] motion. Subsequently, large amounts of mucilage are released to form elongate tubes enmeshing the cell with that object. In post-cytokinetic phases of the cell cycle, mucilage is extruded only through the pole of the developing semi-cell. Chlorotetracyclene-labeling of mucilage-secreting cells show a correlation between calcium-rich loci on the cell surface and sites of mucilage release. 20 refs., 25 figs., 1 tab.« less

Investigation of Tumor Cell Behaviors on a Vascular Microenvironment-Mimicking Microfluidic Chip

PubMed Central

Huang, Rong; Zheng, Wenfu; Liu, Wenwen; Zhang, Wei; Long, Yunze; Jiang, Xingyu

2015-01-01

The extravasation of tumor cells is a key event in tumor metastasis. However, the mechanism underlying tumor cell extravasation remains unknown, mainly hindered by obstacles from the lack of complexity of biological tissues in conventional cell culture, and the costliness and ethical issues of in vivo experiments. Thus, a cheap, time and labor saving, and most of all, vascular microenvironment-mimicking research model is desirable. Herein, we report a microfluidic chip-based tumor extravasation research model which is capable of simultaneously simulating both mechanical and biochemical microenvironments of human vascular systems and analyzing their synergistic effects on the tumor extravasation. Under different mechanical conditions of the vascular system, the tumor cells (HeLa cells) had the highest viability and adhesion activity in the microenvironment of the capillary. The integrity of endothelial cells (ECs) monolayer was destroyed by tumor necrosis factor-α (TNF-α) in a hemodynamic background, which facilitated the tumor cell adhesion, this situation was recovered by the administration of platinum nanoparticles (Pt-NPs). This model bridges the gap between cell culture and animal experiments and is a promising platform for studying tumor behaviors in the vascular system. PMID:26631692

Directing lineage specification of human mesenchymal stem cells by decoupling electrical stimulation and physical patterning on unmodified graphene

NASA Astrophysics Data System (ADS)

Balikov, Daniel A.; Fang, Brian; Chun, Young Wook; Crowder, Spencer W.; Prasai, Dhiraj; Lee, Jung Bok; Bolotin, Kiril I.; Sung, Hak-Joon

2016-07-01

The organization and composition of the extracellular matrix (ECM) have been shown to impact the propagation of electrical signals in multiple tissue types. To date, many studies with electroactive biomaterial substrates have relied upon passive electrical stimulation of the ionic media to affect cell behavior. However, development of cell culture systems in which stimulation can be directly applied to the material - thereby isolating the signal to the cell-material interface and cell-cell contracts - would provide a more physiologically-relevant paradigm for investigating how electrical cues modulate lineage-specific stem cell differentiation. In the present study, we have employed unmodified, directly-stimulated, (un)patterned graphene as a cell culture substrate to investigate how extrinsic electrical cycling influences the differentiation of naïve human mesenchymal stem cells (hMSCs) without the bias of exogenous biochemicals. We first demonstrated that cyclic stimulation does not deteriorate the cell culture media or result in cytotoxic pH, which are critical experiments for correct interpretation of changes in cell behavior. We then measured how the expression of osteogenic and neurogenic lineage-specific markers were altered simply by exposure to electrical stimulation and/or physical patterns. Expression of the early osteogenic transcription factor RUNX2 was increased by electrical stimulation on all graphene substrates, but the mature marker osteopontin was only modulated when stimulation was combined with physical patterns. In contrast, the expression of the neurogenic markers MAP2 and β3-tubulin were enhanced in all electrical stimulation conditions, and were less responsive to the presence of patterns. These data indicate that specific combinations of non-biological inputs - material type, electrical stimulation, physical patterns - can regulate hMSC lineage specification. This study represents a substantial step in understanding how the interplay of electrophysical stimuli regulate stem cell behavior and helps to clarify the potential for graphene substrates in tissue engineering applications.

Effects of membrane properties on the binding activities of the HN and HC heavy-chain domains of botulinum neurotoxin A.

PubMed

Ayyar, B Vijayalakshmi; Atassi, M Zouhair

2016-12-01

Binding behaviors of the H N and the H C domains of BoNT/A were investigated individually to identify if there exist any differences in their interaction with the cell membrane. Recombinant fragments corresponding to both BoNT/A H N and H C regions were prepared (H N 519-845 and H C 967-1296) and their binding to synaptic proteins was verified. The binding behaviors of these heavy-chain domains were analyzed by treating the Neuro 2a, a murine neuroblastoma cell line, with compounds known to alter membrane properties. Cholesterol depletion and lipid raft inhibition increased the binding of H N 519-845 to Neuro 2a cells without affecting H C 967-1296-cell interaction. Sphingolipid depletion decreased the binding of cells to both H C 967-1296 and H N 519-845 whereas, loading exogenous GD1a, on to the Neuro 2a cells, increased the binding of both the peptides to cells. Microtubule disruption of the Neuro 2a cells by nocodazole decreased the binding of both H C 967-1296 and H N 519-845 to the treated cells. Inhibition of the clathrin-mediated endocytosis using dynasore, chlorpromazine or potassium (K + ) depletion buffer lowered the binding of both H C 967-1296 and H N 519-845 to the cells, but seemed to exert a more pronounced effect on the binding of H C 967-1296 than on the binding of H N 519-845. Results indicate that while both the H N and H C domains are involved in the binding of the toxin to neuronal cells there are differences in their behavior which probably stem from their respective amino acid composition and structural location in the toxin three-dimensional structure along with their intended role in translocation and internalization into the cells. Copyright © 2016 Elsevier B.V. All rights reserved.

Numerical Field Model Simulation of Full Scale Fire Tests in a Closed Spherical/Cylindrical Vessel.

DTIC Science & Technology

1987-12-01

the behavior of an actual fire on board a ship. The computer model will be verified by the experimental data obtained in Fire-l. It is important to... behavior in simulations where convection is important. The upwind differencing scheme takes into account the unsymmetrical phenomenon of convection by using...TANK CELL ON THE NORTH SIDE) FOR A * * PARTICULAR FIRE CELL * * COSUMS (I,J) = THE ARRAY TO STORE THE SIMILIAR VALUE FOR THE FIRE * * CELL TO THE SOUTH

Synthesis, characterization and cell behavior of fluoridated hydroxyapatite

NASA Astrophysics Data System (ADS)

Qu, Haibo

Fluorine-containing hydroxyapatite (Ca5(PO4) 3(OH)1-xFx FHA), where F- partially replaces OH- in hydroxyapatite (HA), is recognized as a possible biomaterial for bone and tooth implants and gaining attention in the last several years as a possible alternative to HA. In this study, FHA powders were synthesized through a pH-cycling method. It was discovered that fluorine incorporation increased with the fluorine content in the initial solution and the number of pH cycles employed. A relatively low fluorine incorporation efficiency, ˜60%, was attained for most of the FHA samples. The short time of stay at each pH cycle and the limited number of cycles used are believed to be the main reasons of the low fluorine incorporation into the apatite structure. It was also revealed that the FHA particles produced by the pH-cycling method were inhomogeneous. They were a mixture of hydroxyapatite and F-rich apatite (or FA) particles. The mechanisms of incorporation of fluorine ions into hydroxyapatite by a pH cyclicing method were studied using TEM, XRD and fluorine measurement. Instead of forming laminated structures as reported by other research groups, a mixture of nano-sized F-rich apatite (FHA) and hydroxyapatite (HA) particles were obtained using the pH-cyclicing method. After calcination, these FHA particles were homogenized and became single phased FHA. The effect of fluorine content, preparing method, and sintering temperature on both the bulk density and biaxial flexural strength of sintered FHA was studied. Both uniaxially pressed un-milled (UPU) and cold isostatically pressed milled (IPM) FHA discs were sintered at temperatures between 1200˜400°C at an interval of 100°C. It was found that the fluorine content had a significant impact on the sintering behavior, densification, and mechanical properties of FHA discs. A close correlation between the sintered density and biaxial flexural strength of the specimens was revealed, where the biaxial flexural strength increased exponentially with the sintered density. FHA discs with various fluorine contents have been used to investigate the effect of fluorine content on osteoblastic cell behaviors. Rat osteosarcoma (ROS 17/28) cells were cultured on FHA discs for appropriate times. The osteoblastic cell behaviors were examined in terms of cell attachment, proliferation, morphology and differentiation. The fluorine content in FHA strongly affected the cell activities. More cell attachment and proliferation were observed on the fluorine-containing FHA than pure HA. Fluorine content also affected the differentiation behaviors of osteoblastic cells. Cells on fluorine-containing FHA had higher alkaline phosphatase (ALP) activity than pure HA in 2 weeks. The morphology of the cells showed that it took less time for cells to cover the surface of fluorine-containing samples than that of pure HA. These results suggested that fluorine ions had a significant impact on osteoblastic cell behaviors.

Evidence for deterministic chaos in aperiodic oscillations of acute lymphoblastic leukemia cells in long-term culture

NASA Astrophysics Data System (ADS)

Lambrou, George I.; Chatziioannou, Aristotelis; Vlahopoulos, Spiros; Moschovi, Maria; Chrousos, George P.

Biological systems are dynamic and possess properties that depend on two key elements: initial conditions and the response of the system over time. Conceptualizing this on tumor models will influence conclusions drawn with regard to disease initiation and progression. Alterations in initial conditions dynamically reshape the properties of proliferating tumor cells. The present work aims to test the hypothesis of Wolfrom et al., that proliferation shows evidence for deterministic chaos in a manner such that subtle differences in the initial conditions give rise to non-linear response behavior of the system. Their hypothesis, tested on adherent Fao rat hepatoma cells, provides evidence that these cells manifest aperiodic oscillations in their proliferation rate. We have tested this hypothesis with some modifications to the proposed experimental setup. We have used the acute lymphoblastic leukemia cell line CCRF-CEM, as it provides an excellent substrate for modeling proliferation dynamics. Measurements were taken at time points varying from 24h to 48h, extending the assayed populations beyond that of previous published reports that dealt with the complex dynamic behavior of animal cell populations. We conducted flow cytometry studies to examine the apoptotic and necrotic rate of the system, as well as DNA content changes of the cells over time. The cells exhibited a proliferation rate of nonlinear nature, as this rate presented oscillatory behavior. The obtained data have been fit in known models of growth, such as logistic and Gompertzian growth.

Influence of serum percentage on the behavior of Wharton's jelly mesenchymal stem cells in culture.

PubMed

Harmouch, C; El-Omar, R; Labrude, P; Decot, V; Menu, P; Kerdjoudj, H

2013-01-01

Mesenchymal stem cells (MSCs) are multipotent cells able to differentiate into several lineages with valuable applications in regenerative medicine. MSCs differentiation is highly dependent on physicochemical properties of the culture substrate, cell density and on culture medium composition. In this study, we assessed the influence of fetal bovine serum (FBS) level on Wharton's jelly (WJ)-MSCs behavior seeded on polyelectrolyte multilayer films (PEMF) made of four bilayers of poly-allylamine hydrochloride (PAH) as polycation and poly-styrene sulfonate (PSS) as polyanion. MSCs isolated from WJ by explants method were amplified until the third passage. Their phenotypic characterization was performed by flow cytometry analyses. MSCs were seeded on PEMF, in Endothelial growth medium-2 (EGM-2) supplemented by either 5% or 2% FBS. Cell's behavior was monitored for 20 days by optical microscopy and immunofluorescence. Until 2 weeks on glass slides, no difference was observed whatever the FBS percentage. Then with 5% FBS, MSCs formed three-dimensional spheroids on PSS/PAH after 20 days of culture with a nuclear aggregate. Whereas, with 2% FBS, these spheroids did not appear and cells grown in 2D conserved the fibroblast-like morphology. The decrease of FBS percentage from 5% to 2% avoids 3D cell spheroids formation on PAH/PSS. Such results could guide bioengineering towards building 2D structures like cell layers or 3D structures by increasing the osteogenic or chondrogenic differentiation potential of MSCs.

Knockdown of RhoA expression alters ovarian cancer biological behavior in vitro and in nude mice.

PubMed

Wang, Xiaoxia; Jiang, Wenyan; Kang, Jiali; Liu, Qicai; Nie, Miaoling

2015-08-01

RhoA regulates cell proliferation, migration, angiogenesis and gene expression. Altered RhoA activity contributes to cancer progression. The present study investigated the effects of RhoA knockdown on the regulation of ovarian cancer biological behavior in vitro and in nude mice. The expression of RhoA was knocked down using a lentivirus carrying RhoA short hairpin RNA (shRNA) in ovarian cancer cells and was confirmed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. The altered ovarian cancer biological behaviors were assayed by cell viability, terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling (TUNEL), migration, invasion, and nude mice tumorigenicity assays, while the altered gene expression was detected by RT-qPCR and western blot analysis. The results showed that lentivirus-carrying RhoA shRNA significantly suppressed RhoA expression in ovarian cancer cells, which suppressed tumor cell viability, migration, invasion and adhesion in vitro. RhoA silencing also inhibited the tumorigenicity of ovarian cancer cells in nude mice, which was characterized by the suppression of tumor xenograft formation and growth and induction of tumor cell apoptosis. The results of the present study demonstrated that knockdown of RhoA expression had a significant antitumor effect on ovarian cancer cells in vitro and in nude mice, suggesting that RhoA may be a target for the development of a novel therapeutic strategy in the control of ovarian cancer.

Mechanical behavior of cells in microinjection: a minimum potential energy study.

PubMed

Liu, Fei; Wu, Dan; Chen, Ken

2013-08-01

Microinjection is a widely used technique to deliver foreign materials into biological cells. We propose a mathematical model to study the mechanical behavior of a cell in microinjection. Firstly, a cell is modeled by a hyperelastic membrane and interior cytoplasm. Then, based on the fact that the equilibrium configuration of a cell would minimize the potential energy, the energy function during microinjection is analyzed. With Lagrange multiplier and Rayleigh-Ritz technique, we successfully minimize the potential energy and obtain the equilibrium configuration. Upon this model, the injection force, the injection distance, the radius of the microinjector and the membrane stress are studied. The analysis demonstrates that the microinjector radius has a significant influence on the cell mechanical behavior: (1) the larger radius generates larger injection force and larger interior pressure at the same injection distance; (2) the radius determines the place where the membrane is most likely to rupture by governing the membrane stress distribution. For a fine microinjector with radius less than 20% of the cell radius, the most likely rupture point located at the edge of the contact area between the microinjector and the membrane; however, it may move to the middle of the equilibrium configuration as the radius increases. To verify our model, some experiments were conducted on zebrafish egg cells. The results show that the computational analysis agrees with the experimental data, which supports the findings from the theoretical model. Copyright © 2013 Elsevier Ltd. All rights reserved.

Single-cell Genomics using Droplet-based Microfluidics

NASA Astrophysics Data System (ADS)

Basu, Anindita; Macosko, Evan; Shalek, Alex; McCarroll, Steven; Regev, Aviv; Weitz, Dave

2014-03-01

We develop a system to profile the transcriptome of mammalian cells in isolation using reverse emulsion droplet-based microfluidic techniques. This is accomplished by (a) encapsulating and lysing one cell per emulsion droplet, and (b) uniquely barcoding the RNA contents from each cell using unique DNA-barcoded microgel beads. This enables us to study the transcriptional behavior of a large number of cells at single-cell resolution. We then use these techniques to study transcriptional responses of isolated immune cells to precisely controlled chemical and pathological stimuli provided in the emulsion droplet.

Patterning C. elegans: homeotic cluster genes, cell fates and cell migrations.

PubMed

Salser, S J; Kenyon, C

1994-05-01

Despite its simple body form, the nematode C. elegans expresses homeotic cluster genes similar to those of insects and vertebrates in the patterning of many cell types and tissues along the anteroposterior axis. In the ventral nerve cord, these genes program spatial patterns of cell death, fusion, division and neurotransmitter production; in migrating cells they regulate the direction and extent of movement. Nematode development permits an analysis at the cellular level of how homeotic cluster genes interact to specify cell fates, and how cell behavior can be regulated to assemble an organism.

Multifunctional ferromagnetic disks for modulating cell function

PubMed Central

Vitol, Elina A.; Novosad, Valentyn; Rozhkova, Elena A.

2013-01-01

In this work, we focus on the methods for controlling cell function with ferromagnetic disk-shaped particles. We will first review the history of magnetically assisted modulation of cell behavior and applications of magnetic particles for studying physical properties of a cell. Then, we consider the biological applications of the microdisks such as the method for induction of cancer cell apoptosis, controlled drug release, hyperthermia and MRI imaging. PMID:23766544

Identification, Characterization, and Utilization of Adult Meniscal Progenitor Cells

DTIC Science & Technology

2015-09-01

pluripotent stem cells for osteoarthritis drug screening . Arthritis Rheumatol. 66, 3062–3072. Xia, Y., Zheng, S., Bidthanapally, A., 2008. Depth-dependent...the development of knee osteoarthritis (OA). New treatments centered on the stem /progenitor cell population resident within the adult meniscus will be...biology to develop a profile of repair cells in the adult meniscus, track meniscal stem /progenitor cell (MSPC) behavior within meniscus as function of

Mechanics of vimentin intermediate filaments

NASA Technical Reports Server (NTRS)

Wang, Ning; Stamenovic, Dimitrijie

2002-01-01

It is increasingly evident that the cytoskeleton of living cells plays important roles in mechanical and biological functions of the cells. Here we focus on the contribution of intermediate filaments (IFs) to the mechanical behaviors of living cells. Vimentin, a major structural component of IFs in many cell types, is shown to play an important role in vital mechanical and biological functions such as cell contractility, migration, stiffness, stiffening, and proliferation.

Merkel cell carcinoma in an immunosuppressed patient.

PubMed

Góes, Heliana Freitas de Oliveira; Lima, Caren Dos Santos; Issa, Maria Cláudia de Almeida; Luz, Flávio Barbosa; Pantaleão, Luciana; Paixão, José Gabriel Miranda da

2017-01-01

Merkel cell carcinoma is an uncommon neuroendocrine carcinoma with a rising incidence and an aggressive behavior. It predominantly occurs in older patients, with onset occurring at a mean age of 75-80 years. Recognized risk factors are ultraviolet sunlight exposure, immunosuppression, and, more recently, Merkel cell polyomavirus. We report a case of Merkel cell carcinoma in a young HIV positive patient with Merkel Cell polyomavirus detected in the tumor.

Magnetic Particle Spectroscopy Reveals Dynamic Changes in the Magnetic Behavior of Very Small Superparamagnetic Iron Oxide Nanoparticles During Cellular Uptake and Enables Determination of Cell-Labeling Efficacy.

PubMed

Poller, Wolfram C; Löwa, Norbert; Wiekhorst, Frank; Taupitz, Matthias; Wagner, Susanne; Möller, Konstantin; Baumann, Gert; Stangl, Verena; Trahms, Lutz; Ludwig, Antje

2016-02-01

In vivo tracking of nanoparticle-labeled cells by magnetic resonance imaging (MRI) crucially depends on accurate determination of cell-labeling efficacy prior to transplantation. Here, we analyzed the feasibility and accuracy of magnetic particle spectroscopy (MPS) for estimation of cell-labeling efficacy in living THP-1 cells incubated with very small superparamagnetic iron oxide nanoparticles (VSOP). Cell viability and proliferation capacity were not affected by the MPS measurement procedure. In VSOP samples without cell contact, MPS enabled highly accurate quantification. In contrast, MPS constantly overestimated the amount of cell associated and internalized VSOP. Analyses of the MPS spectrum shape expressed as harmonic ratio A₅/A₃ revealed distinct changes in the magnetic behavior of VSOP in response to cellular uptake. These changes were proportional to the deviation between MPS and actual iron amount, therefore allowing for adjusted iron quantification. Transmission electron microscopy provided visual evidence that changes in the magnetic properties correlated with cell surface interaction of VSOP as well as with alterations of particle structure and arrangement during the phagocytic process. Altogether, A₅/A₃-adjusted MPS enables highly accurate, cell-preserving VSOP quantification and furthermore provides information on the magnetic characteristics of internalized VSOP.

Stem cell responses to plasma surface modified electrospun polyurethane scaffolds.

PubMed

Zandén, Carl; Hellström Erkenstam, Nina; Padel, Thomas; Wittgenstein, Julia; Liu, Johan; Kuhn, H Georg

2014-07-01

The topographical effects from functional materials on stem cell behavior are currently of interest in tissue engineering and regenerative medicine. Here we investigate the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell (hESC) and rat postnatal neural stem cell (NSC) responses. The plasma gases were found to induce three combinations of fiber surface functionalities and roughness textures. On randomly oriented fibers, plasma treatments lead to substantially increased hESC attachment and proliferation as compared to native fibers. Argon plasma was found to induce the most optimal combination of surface functionality and roughness for cell expansion. Contact guided migration of cells and alignment of cell processes were observed on aligned fibers. Neuronal differentiation around 5% was found for all samples and was not significantly affected by the induced variations of surface functional group distribution or individual fiber topography. In this study the influence of argon, oxygen, and hydrogen plasma surface modification of electrospun polyurethane fibers on human embryonic stem cell and rat postnatal neural stem cell (NSC) responses is studied with the goal of clarifying the potential effects of functional materials on stem cell behavior, a topic of substantial interest in tissue engineering and regenerative medicine. Copyright © 2014 Elsevier Inc. All rights reserved.

Voltage instability in a simulated fuel cell stack correlated to cathode water accumulation

NASA Astrophysics Data System (ADS)

Owejan, J. P.; Trabold, T. A.; Gagliardo, J. J.; Jacobson, D. L.; Carter, R. N.; Hussey, D. S.; Arif, M.

Single fuel cells running independently are often used for fundamental studies of water transport. It is also necessary to assess the dynamic behavior of fuel cell stacks comprised of multiple cells arranged in series, thus providing many paths for flow of reactant hydrogen on the anode and air (or pure oxygen) on the cathode. In the current work, the flow behavior of a fuel cell stack is simulated by using a single-cell test fixture coupled with a bypass flow loop for the cathode flow. This bypass simulates the presence of additional cells in a stack and provides an alternate path for airflow, thus avoiding forced convective purging of cathode flow channels. Liquid water accumulation in the cathode is shown to occur in two modes; initially nearly all the product water is retained in the gas diffusion layer until a critical saturation fraction is reached and then water accumulation in the flow channels begins. Flow redistribution and fuel cell performance loss result from channel slug formation. The application of in-situ neutron radiography affords a transient correlation of performance loss to liquid water accumulation. The current results identify a mechanism whereby depleted cathode flow on a single cell leads to performance loss, which can ultimately cause an operating proton exchange membrane fuel cell stack to fail.

Size and competitive mating success in the yeast Saccharomyces cerevisiae.

PubMed

Smith, Carl; Pomiankowski, Andrew; Greig, Duncan

2014-03-01

In unicellular organisms like yeast, mating with the right partner is critical to future fitness because each individual can only mate once. Because cell size is important for viability, mating with a partner of the right size could be a significant advantage. To investigate this idea, we manipulated the size of unmated yeast cells and showed that their viability depended on environmental conditions; large cells do better on rich medium and small cells do better on poor medium. We also found that the fitness of offspring is determined by the size of their parents. Finally, we demonstrated that when a focal cell of one mating type was placed with a large and a small cell of the opposite mating type, it was more likely to mate with the cell that was closer to the optimum size for growth in a given environment. This pattern was not generated by differences in passive mating efficiency of large and small cells across environments but by competitive mating behavior, mate preference, or both. We conclude that the most likely mechanism underlying this interesting behavior is that yeast cells compete for mates by producing pheromone signals advertising their viability, and cells with the opportunity to choose prefer to mate with stronger signalers because such matings produce more viable offspring.

Effect of graphene oxide ratio on the cell adhesion and growth behavior on a graphene oxide-coated silicon substrate

NASA Astrophysics Data System (ADS)

Jeong, Jin-Tak; Choi, Mun-Ki; Sim, Yumin; Lim, Jung-Taek; Kim, Gil-Sung; Seong, Maeng-Je; Hyung, Jung-Hwan; Kim, Keun Soo; Umar, Ahmad; Lee, Sang-Kwon

2016-09-01

Control of living cells on biocompatible materials or on modified substrates is important for the development of bio-applications, including biosensors and implant biomaterials. The topography and hydrophobicity of substrates highly affect cell adhesion, growth, and cell growth kinetics, which is of great importance in bio-applications. Herein, we investigate the adhesion, growth, and morphology of cultured breast cancer cells on a silicon substrate, on which graphene oxides (GO) was partially formed. By minimizing the size and amount of the GO-containing solution and the further annealing process, GO-coated Si samples were prepared which partially covered the Si substrates. The coverage of GO on Si samples decreases upon annealing. The behaviors of cells cultured on two samples have been observed, i.e. partially GO-coated Si (P-GO) and annealed partially GO-coated Si (Annealed p-GO), with a different coverage of GO. Indeed, the spreading area covered by the cells and the number of cells for a given culture period in the incubator were highly dependent on the hydrophobicity and the presence of oxygenated groups on GO and Si substrates, suggesting hydrophobicity-driven cell growth. Thus, the presented method can be used to control the cell growth via an appropriate surface modification.

Mechanisms of cellular uptake, intracellular transportation, and degradation of CIGB-300, a Tat-conjugated peptide, in tumor cell lines.

PubMed

Benavent Acero, Fernando R; Perera Negrin, Yasser; Alonso, Daniel F; Perea, Silvio E; Gomez, Daniel E; Farina, Hernán G

2014-06-02

CIGB-300 is a cyclic synthetic peptide that induces apoptosis in malignant cells, elicits antitumor activity in cancer animal models, and shows tumor reduction signs when assayed in first-in-human phase I trial in patients with cervical tumors. CIGB-300 impairs phosphorylation by casein kinase 2 through targeting the substrate's phosphoacceptor domain. CIGB-300 was linked to the cell penetrating peptide Tat to facilitate the delivery into cells. Previously, we showed that CIGB-300 had a differential antiproliferative behavior in different tumor cell lines. In this work, we studied differential antiproliferative behavior in terms of cellular uptake, intracellular transportation, and degradation in tumor cell lines with dissimilar sensitivity to CIGB-300. The internalization of CIGB-300 was studied in different malignant cell lines. We found that the cell membrane heparan sulfate proteoglycans act as main receptors for extracellular CIGB-300 uptake. The most sensitive tumor cell lines showed higher intracellular incorporation of CIGB-300 in comparison to less sensitive cell lines. Furthermore, CIGB-300 uptake is time- and concentration-dependent in all studied cell lines. It was shown that CIGB-300 has the ability to penetrate cells mainly by direct membrane translocation. However, a minor proportion of the peptide uses an energy-dependent endocytic pathway mechanism to gain access into cells. CIGB-300 is internalized and transported into cells preferentially by caveolae-mediated endocytosis. Lysosomes are involved in CIGB-300 degradation; highly sensitive cell lines showed degradation at earlier times compared to low sensitive cells. Altogether, our data suggests a mechanism of internalization, vesicular transportation, and degradation for CIGB-300 in tumor cells.

Convective exosome-tracing microfluidics for analysis of cell-non-autonomous neurogenesis.

PubMed

Oh, Hyun Jeong; Shin, Yoojin; Chung, Seok; Hwang, Do Won; Lee, Dong Soo

2017-01-01

The effective role of exosome delivering neurogenic microRNA (miRNA) enables to induce efficient differentiation process during neurogenesis. The microfludic system capable of visualizing the exosomal behavior such as secretion, migration, and uptake of individual exosomes can be used as a robust technique to understand the exosome-mediated change of cellular behavior. Here, we developed the exosome-tracing microfluidic system to visualize exosomal transport carrying the neurogenic miRNA from leading to neighboring cells, and found a new mode of exosome-mediated cell-non-autonomous neurogenesis. The miR-193a facilitated neurogenesis in F11 cells by blocking proliferation-related target genes. In addition to time-lapse live-cell imaging using microfluidics visualized the convective transport of exosomes from differentiated to undifferentiated cells. Individual exosomes containing miR-193a from differentiated donor cells were taken up by undifferentiated cells to lead them to neurogenesis. Induction of anti-miR-193a was sufficient to block neurogenesis in F11 cells. Inhibition of the exosomal production by manumycin-A and treatment of anti-miR-193a in the differentiated donor cells failed to induce neurogenesis in undifferentiated recipient cells. These findings indicate that exosomes of neural progenitors and neurogenic miRNA within these exosomes propagate cell-non-autonomous differentiation to neighboring progenitors, to delineate the roles of exosome mediating neurogenesis of population of homologous neural progenitor cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

Statistical Characterization of 18650-Format Lithium-Ion Cell Thermal Runaway Energy Distributions

NASA Technical Reports Server (NTRS)

Walker, William Q.; Rickman, Steven; Darst, John; Finegan, Donal; Bayles, Gary; Darcy, Eric

2017-01-01

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing vs. through the ejecta material. A unique calorimeter was utilized to examine the TR behavior of a statistically significant number of 18650-format Li-ion cells with varying manufacturers, chemistries, and capacities. The calorimeter was designed to contain the TR energy in a format conducive to discerning the fractions of energy released through the cell casing vs. through the ejecta material. Other benefits of this calorimeter included the ability to rapidly test of large quantities of cells and the intentional minimization of secondary combustion effects. High energy (270 Wh/kg) and moderate energy (200 Wh/kg) 18650 cells were tested. Some of the cells had an imbedded short circuit (ISC) device installed to aid in the examination of TR mechanisms under more realistic conditions. Other variations included cells with bottom vent (BV) features and cells with thin casings (0.22 1/4m). After combining the data gathered with the calorimeter, a statistical approach was used to examine the probability of certain TR behavior, and the associated energy distributions, as a function of capacity, venting features, cell casing thickness and temperature.

Isolating LacZ-expressing cells from mouse inner ear tissues using flow cytometry.

PubMed

Jan, Taha A; Chai, Renjie; Sayyid, Zahra N; Cheng, Alan G

2011-12-23

Isolation of specific cell types allows one to analyze rare cell populations such as stem/progenitor cells. Such an approach to studying inner ear tissues presents a unique challenge because of the paucity of cells of interest and few transgenic reporter mouse models. Here, we describe a protocol using fluorescence-conjugated probes to selectively label LacZ-positive cells from the neonatal cochleae. The most common underlying pathology of sensorineural hearing loss is the irreversible damage and loss of cochlear sensory hair cells, which are required to transduce sound waves to neural impulses. Recent evidence suggests that the murine auditory and vestibular organs harbor stem/progenitor cells that may have regenerative potential. These findings warrant further investigation, including identifying specific cell types with stem/progenitor cell characteristics. The Wnt signaling pathway has been demonstrated to play a critical role in maintaining stem/progenitor cell populations in several organ systems. We have recently identified Wnt-responsive Axin2-expressing cells in the neonatal cochlea, but their function is largely unknown. To better understand the behavior of these Wnt-responsive cells in vitro, we have developed a method of isolating Axin2-expressing cells from cochleae of Axin2-LacZ reporter mice. Using flow cytometry to isolate Axin2-LacZ positive cells from the neonatal cochleae, we could in turn execute a variety of experiments on live cells to interrogate their behavior as stem/progenitor cells. Here, we describe in detail the steps for the microdissection of neonatal cochlea, dissociation of these tissues, labeling of the LacZ-positive cells using a fluorogenic substrate, and cell sorting. Techniques for dissociating cochleae into single cells and isolating cochlear cells via flow cytometry have been described. We have made modifications to these techniques to establish a novel protocol to isolate LacZ-expressing cells from the neonatal cochlea.

Transposon tagging of genes for cell-cell interactions in Myxococcus xanthus.

PubMed Central

Kalos, M; Zissler, J

1990-01-01

The prokaryote Myxococcus xanthus is a model for cell interactions important in multicellular behavior. We used the transposon TnphoA to specifically identify genes for cell-surface factors involved in cell interactions. From a library of 10,700 insertions of TnphoA, we isolated 36 that produced alkaline phosphatase activity. Three TnphoA insertions tagged cell motility genes, called cgl, which control the adventurous movement of cells. The products of the tagged cgl genes could function in trans upon other cells and were localized primarily in the cell envelope and extracellular space, consistent with TnphoA tagging genes for extracellular factors controlling motility. Images PMID:2172982

Social Competition in Rats: Cell Proliferation and Behavior

PubMed Central

Hoshaw, Brian A.; Evans, Jennifer C.; Mueller, Bridget; Valentino, Rita J.; Lucki, Irwin

2007-01-01

Behavioral and physiological changes were studied following prolonged exposure to social competition in pairs of non food-deprived rats competing daily for a limited supply of graham cracker crumbs. Stable dominant-subordinate relationships developed in most pairs, as measured by feeding time, which were maintained over a 5–6-week study period. In other behavioral tests, subordinates demonstrated a decreased latency to immobility in the forced swim test compared with dominants, but no difference in locomotor activity. Subordinates had increased bladder size, decreased adrenal gland size, and a 35% reduction of hippocampus cell proliferation compared with the dominant member. Therefore, prolonged social competition, based on restricted access to palatable substances, produced hierarchies among individuals that were associated with differences in behavior, physiology and hippocampal cell proliferation. PMID:17045347

Improved attachment of mesenchymal stem cells on super-hydrophobic TiO2 nanotubes.

PubMed

Bauer, Sebastian; Park, Jung; von der Mark, Klaus; Schmuki, Patrik

2008-09-01

Self-organized layers of vertically orientated TiO(2) nanotubes providing defined diameters ranging from 15 up to 100nm were grown on titanium by anodic oxidation. These TiO(2) nanotube layers show super-hydrophilic behavior. After coating TiO(2) nanotube layers with a self-assembled monolayer (octadecylphosphonic acid) they showed a diameter-dependent wetting behavior ranging from hydrophobic (108+/-2 degrees ) up to super-hydrophobic (167+/-2 degrees ). Cell adhesion, spreading and growth of mesenchymal stem cells on the unmodified and modified nanotube layers were investigated and compared. We show that cell adhesion and proliferation are strongly affected in the super-hydrophobic range. Adsorption of extracellular matrix proteins as fibronectin, type I collagen and laminin, as well as bovine serum albumin, on the coated and uncoated surfaces showed a strong influence on wetting behavior and dependence on tube diameter.

Thin and small form factor cells : simulated behavior.

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

Clews, Peggy Jane; Pluym, Tammy; Grubbs, Robert K.

Thin and small form factor cells have been researched lately by several research groups around the world due to possible lower assembly costs and reduced material consumption with higher efficiencies. Given the popularity of these devices, it is important to have detailed information about the behavior of these devices. Simulation of fabrication processes and device performance reveals some of the advantages and behavior of solar cells that are thin and small. Three main effects were studied: the effect of surface recombination on the optimum thickness, efficiency, and current density, the effect of contact distance on the efficiency for thin cells,more » and lastly the effect of surface recombination on the grams per Watt-peak. Results show that high efficiency can be obtained in thin devices if they are well-passivated and the distance between contacts is short. Furthermore, the ratio of grams per Watt-peak is greatly reduced as the device is thinned.« less

Coordination of cell death and the cell cycle: linking proliferation to death through private and communal couplers.

PubMed

Abrams, John M; White, Michael A

2004-12-01

In development and in the adult, complex signaling pathways operate within and between cells to coordinate proliferation and cell death. These networks can be viewed as coupling devices that link engines driving the cell cycle and the initiation of apoptosis. We propose three simple frameworks for modeling the effects of proliferative drive on apoptotic propensity. This perspective offers a potentially useful foundation for predicting group behaviors of cells in normal and pathological settings.

Basic Techniques in Mammalian Cell Tissue Culture.

PubMed

Phelan, Katy; May, Kristin M

2016-11-01

Cultured mammalian cells are used extensively in cell biology studies. It requires a number of special skills in order to be able to preserve the structure, function, behavior, and biology of the cells in culture. This unit describes the basic skills required to maintain and preserve cell cultures: maintaining aseptic technique, preparing media with the appropriate characteristics, passaging, freezing and storage, recovering frozen stocks, and counting viable cells. © 2016 by John Wiley & Sons, Inc. Copyright © 2016 John Wiley & Sons, Inc.

Calcium Imaging of Basal Forebrain Activity during Innate and Learned Behaviors

PubMed Central

Harrison, Thomas C.; Pinto, Lucas; Brock, Julien R.; Dan, Yang

2016-01-01

The basal forebrain (BF) plays crucial roles in arousal, attention, and memory, and its impairment is associated with a variety of cognitive deficits. The BF consists of cholinergic, GABAergic, and glutamatergic neurons. Electrical or optogenetic stimulation of BF cholinergic neurons enhances cortical processing and behavioral performance, but the natural activity of these cells during behavior is only beginning to be characterized. Even less is known about GABAergic and glutamatergic neurons. Here, we performed microendoscopic calcium imaging of BF neurons as mice engaged in spontaneous behaviors in their home cages (innate) or performed a go/no-go auditory discrimination task (learned). Cholinergic neurons were consistently excited during movement, including running and licking, but GABAergic and glutamatergic neurons exhibited diverse responses. All cell types were activated by overt punishment, either inside or outside of the discrimination task. These findings reveal functional similarities and distinctions between BF cell types during both spontaneous and task-related behaviors. PMID:27242444

A comparative study of the annealing behavior of Cu(In,Ga)(S,Se){sub 2} based solar cells with an indium sulfide buffer layer, partly submitted to wet chemical treatments

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

Hönes, C., E-mail: christian.hoenes@de.bosch.com; Laboratory for Photovoltaics, University of Luxembourg, 41 rue du Brill, L-4422 Belvaux; Hackenberg, J.

2015-03-07

Indium sulfide thin films deposited via thermal evaporation from compound source material have been successfully utilized as a cadmium free buffer layer for Cu(In,Ga)Se{sub 2} based solar cells. However, high efficiencies are only reached after an additional annealing step. In this work, the annealing behavior of Cu(In,Ga)(S,Se){sub 2} based indium sulfide buffered solar cells is compared to the annealing behavior of similar cells, which were submitted to wet chemical treatments partly containing cadmium ions. Upon annealing a significant improvement of the initial solar cell characteristics is observed for the untreated cell and is related to the increase of activation energymore » for the carrier recombination process and a decrease of the ideality factor within the one diode model. It is shown here that this improvement can also be achieved by wet treatments of the absorber prior to buffer layer deposition. Upon annealing these treated cells still gain in collection length but lose open circuit voltage, which is explained here within a model including a highly p-doped absorber surface layer and supported by simulations showing that a decrease in doping density of such a surface layer would lead to the observed effects.« less

Polysaccharide-based hydrogels with tunable composition as 3D cell culture systems.

PubMed

Gentilini, Roberta; Munarin, Fabiola; Bloise, Nora; Secchi, Eleonora; Visai, Livia; Tanzi, Maria Cristina; Petrini, Paola

2018-04-01

To date, cell cultures have been created either on 2-dimensional (2D) polystyrene surfaces or in 3-dimensional (3D) systems, which do not offer a controlled chemical composition, and which lack the soft environment encountered in vivo and the chemical stimuli that promote cell proliferation and allow complex cellular behavior. In this study, pectin-based hydrogels were developed and are proposed as versatile cell culture systems. Pectin-based hydrogels were produced by internally crosslinking pectin with calcium carbonate at different initial pH, aiming to control crosslinking kinetics and degree. Additionally, glucose and glutamine were added as additives, and their effects on the viscoelastic properties of the hydrogels and on cell viability were investigated. Pectin hydrogels showed in high cell viability and shear-thinning behavior. Independently of hydrogel composition, an initial swelling was observed, followed by a low percentage of weight variation and a steady-state stage. The addition of glucose and glutamine to pectin-based hydrogels rendered higher cell viability up to 90%-98% after 1 hour of incubation, and these hydrogels were maintained for up to 7 days of culture, yet no effect on viscoelastic properties was detected. Pectin-based hydrogels that offer tunable composition were developed successfully. They are envisioned as synthetic extracellular matrix (ECM) either to study complex cellular behaviors or to be applied as tissue engineering substitutes.

“Engineering Substrate Micro- and Nanotopography to Control Cell Function”

PubMed Central

Bettinger, Christopher J; Langer, Robert; Borenstein, Jeffrey T

2010-01-01

Lead-In The interaction of mammalian cells with nanoscale topography has proven to be an important signaling modality in controlling cell function. Naturally occurring nanotopographic structures within the extracellular matrix present surrounding cells with mechanotransductive cues that influence local migration, cell polarization, and other functions. Synthetically nanofabricated topography can also influence cell morphology, alignment, adhesion, migration, proliferation, and cytoskeleton organization. Here we review the use of in vitro synthetic cell-nanotopography interactions to control cell behavior and influence complex cellular processes including stem cell differentiation and tissue organization. Future challenges and opportunities in cell-nanotopography engineering will also be discussed including the elucidation of mechanisms and applications in tissue engineering. PMID:19492373

Downregulation of the expression of HDGF attenuates malignant biological behaviors of hilar cholangiocarcinoma cells.

PubMed

Liu, Yanfeng; Sun, Jingxian; Yang, Guangyun; Liu, Zhaojian; Guo, Sen; Zhao, Rui; Xu, Kesen; Wu, Xiaopeng; Zhang, Zhaoyang

2015-09-01

Hepatoma-derived growth factor (HDGF) has been reported to be a potential predictive and prognostic marker for several types of cancer and important in malignant biological behaviors. However, its role in human hilar cholangiocarcinoma remains to be elucidated. Our previous study demonstrated that high expression levels of HDGF in hilar cholangiocarcinoma tissues correlates with tumor progression and patient outcome. The present study aimed to elucidate the detailed functions of the HDGF protein. This was performed by downregulating the protein expression of HDGF in the FRH0201 hilar cholangiocarcinoma cell line by RNA interference (RNAi) in vitro, and revealed that downregulation of the HDGF protein significantly inhibited the malignant biological behavior of the FRH0201 cells. In addition, further investigation revealed that downregulation of the protein expression of HDGF significantly decreased the secretion of vascular endothelial growth factor, which may be the mechanism partially responsible for the inhibition of malignant biological behaviors. These findings demonstrated that HDGF is important in promoting malignant biological behaviors, including proliferation, migration and invasion of hilar cholangiocarcinoma FRH0201 cells. Inhibition of the expression of HDGF downregulated the malignant biological behaviors, suggesting that downregulation of the protein expression of HDGF by RNAi may be a novel therapeutic approach to inhibit the progression of hilar cholangiocarcinoma.

High-throughput separation of cells by dielectrophoresis enhanced with 3D gradient AC electric field.

PubMed

Tada, Shigeru; Hayashi, Masako; Eguchi, Masanori; Tsukamoto, Akira

2017-11-01

We propose a novel, high-performance dielectrophoretic (DEP) cell-separation flow chamber with a parallel-plate channel geometry. The flow chamber, consisting of a planar electrode on the top and an interdigitated-pair electrode array at the bottom, was developed to facilitate the separation of cells by creating a nonuniform AC electric field throughout the volume of the flow chamber. The operation and performance of the device were evaluated using live and dead human epithermal breast (MCF10A) cells. The separation dynamics of the cell suspension in the flow chamber was also investigated by numerically simulating the trajectories of individual cells. A theoretical model to describe the dynamic cell behavior under the action of DEP, including dipole-dipole interparticle, viscous, and gravitational forces, was developed. The results demonstrated that the live cells traveling through the flow chamber congregated into sites where the electric field gradient was minimal, in the middle of the flow stream slightly above the centerlines of the grounded electrodes at the bottom. Meanwhile, the dead cells were trapped on the edges of the high-voltage electrodes at the bottom. Cells were thus successfully separated with a remarkably high separation ratio (∼98%) at the appropriately tuned field frequency and applied voltage. The numerically predicted behavior and spatial distribution of the cells during separation also showed good agreement with those observed experimentally.

Ultra-fast laser microprocessing of medical polymers for cell engineering applications.

PubMed

Ortiz, R; Moreno-Flores, S; Quintana, I; Vivanco, MdM; Sarasua, J R; Toca-Herrera, J L

2014-04-01

Picosecond laser micromachining technology (PLM) has been employed as a tool for the fabrication of 3D structured substrates. These substrates have been used as supports in the in vitro study of the effect of substrate topography on cell behavior. Different micropatterns were PLM-generated on polystyrene (PS) and poly-L-lactide (PLLA) and employed to study cellular proliferation and morphology of breast cancer cells. The laser-induced microstructures included parallel lines of comparable width to that of a single cell (which in this case is roughly 20μm), and the fabrication of square-like compartments of a much larger area than a single cell (250,000μm(2)). The results obtained from this in vitro study showed that though the laser treatment altered substrate roughness, it did not noticeably affect the adhesion and proliferation of the breast cancer cells. However, pattern direction directly affected cell proliferation, leading to a guided growth of cell clusters along the pattern direction. When cultured in square-like compartments, cells remained confined inside these for eleven incubation days. According to these results, laser micromachining with ultra-short laser pulses is a suitable method to directly modify the cell microenvironment in order to induce a predefined cellular behavior and to study the effect of the physical microenvironment on cell proliferation. Copyright © 2013 Elsevier B.V. All rights reserved.

Bursting synchronization dynamics of pancreatic β-cells with electrical and chemical coupling.

PubMed

Meng, Pan; Wang, Qingyun; Lu, Qishao

2013-06-01

Based on bifurcation analysis, the synchronization behaviors of two identical pancreatic β-cells connected by electrical and chemical coupling are investigated, respectively. Various firing patterns are produced in coupled cells when a single cell exhibits tonic spiking or square-wave bursting individually, irrespectively of what the cells are connected by electrical or chemical coupling. On the one hand, cells can burst synchronously for both weak electrical and chemical coupling when an isolated cell exhibits tonic spiking itself. In particular, for electrically coupled cells, under the variation of the coupling strength there exist complex transition processes of synchronous firing patterns such as "fold/limit cycle" type of bursting, then anti-phase continuous spiking, followed by the "fold/torus" type of bursting, and finally in-phase tonic spiking. On the other hand, it is shown that when the individual cell exhibits square-wave bursting, suitable coupling strength can make the electrically coupled system generate "fold/Hopf" bursting via "fold/fold" hysteresis loop; whereas, the chemically coupled cells generate "fold/subHopf" bursting. Especially, chemically coupled bursters can exhibit inverse period-adding bursting sequence. Fast-slow dynamics analysis is applied to explore the generation mechanism of these bursting oscillations. The above analysis of bursting types and the transition may provide us with better insight into understanding the role of coupling in the dynamic behaviors of pancreatic β-cells.

Retention and transport of an anaerobic trichloroethene dechlorinating microbial culture in anaerobic porous media.

PubMed

Zhang, Huixin; Ulrich, Ania C; Liu, Yang

2015-06-01

The influence of solution chemistry on microbial transport was examined using the strictly anaerobic trichloroethene (TCE) bioaugmentation culture KB-1(®). A column was employed to determine transport behaviors and deposition kinetics of three distinct functional species in KB-1(®), Dehalococcoides, Geobacter, and Methanomethylovorans, over a range of ionic strengths under a well-controlled anaerobic condition. A quantitative polymerase chain reaction (qPCR) was utilized to enumerate cell concentration and complementary techniques were implemented to evaluate cell surface electrokinetic potentials. Solution chemistry was found to positively affect the deposition rates, which was consistent with calculated Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energies. Retained microbial profiles showed spatially constant colloid deposition rate coefficients, in agreement with classical colloid filtration theory (CFT). It was interesting to note that the three KB-1(®) species displayed similar transport and retention behaviors under the defined experimental conditions despite their different cell electrokinetic properties. A deeper analysis of cell characteristics showed that factors, such as cell size and shape, concentration, and motility were involved in determining adhesion behavior. Copyright © 2015 Elsevier B.V. All rights reserved.

Anisotropic shear stress patterns predict the orientation of convergent tissue movements in the embryonic heart

PubMed Central

2017-01-01

Myocardial contractility and blood flow provide essential mechanical cues for the morphogenesis of the heart. In general, endothelial cells change their migratory behavior in response to shear stress patterns, according to flow directionality. Here, we assessed the impact of shear stress patterns and flow directionality on the behavior of endocardial cells, the specialized endothelial cells of the heart. At the early stages of zebrafish heart valve formation, we show that endocardial cells are converging to the valve-forming area and that this behavior depends upon mechanical forces. Quantitative live imaging and mathematical modeling allow us to correlate this tissue convergence with the underlying flow forces. We predict that tissue convergence is associated with the direction of the mean wall shear stress and of the gradient of harmonic phase-averaged shear stresses, which surprisingly do not match the overall direction of the flow. This contrasts with the usual role of flow directionality in vascular development and suggests that the full spatial and temporal complexity of the wall shear stress should be taken into account when studying endothelial cell responses to flow in vivo. PMID:29183943

Lithium-manganese dioxide cells for implantable defibrillator devices-Discharge voltage models

NASA Astrophysics Data System (ADS)

Root, Michael J.

The discharge potential behavior of lithium-manganese dioxide cells designed for implantable cardiac defibrillators was characterized as a function of extent of cell depletion for tests designed to discharge the cells for times between 1 and 7 years. The discharge potential curves may be separated into two segments from 0 ≤ x ≤ ∼0.51 and ∼0.51 ≤ x ≤ 1.00, where x is the dimensionless extent of discharge referenced to the rated cell capacity. The discharge potentials conform to Tafel kinetics in each segment. This behavior allows the discharge potential curves to be predicted for an arbitrary discharge load and long term discharge performance may be predicted from short term test results. The discharge potentials may subsequently be modeled by fitting the discharge curves to empirical functions like polynomials and Padé approximants. A function based on the Nernst equation that includes a term accounting for nonideal interactions between lithium ions and the cathode host material, such as the Redlich-Kister relationship, also may be used to predict discharge behavior.

Using GPS-enabled cell phones to track the travel patterns of adolescents.

PubMed

Wiehe, Sarah E; Carroll, Aaron E; Liu, Gilbert C; Haberkorn, Kelly L; Hoch, Shawn C; Wilson, Jeffery S; Fortenberry, J Dennis

2008-05-21

Few tools exist to directly measure the microsocial and physical environments of adolescents in circumstances where participatory observation is not practical or ethical. Yet measuring these environments is important as they are significantly associated with adolescent health-risk. For example, health-related behaviors such as cigarette smoking often occur in specific places where smoking may be relatively surreptitious. We assessed the feasibility of using GPS-enabled cell phones to track adolescent travel patterns and gather daily diary data. We enrolled 15 adolescent women from a clinic-based setting and asked them to carry the phones for 1 week. We found that these phones can accurately and reliably track participant locations, as well as record diary information on adolescent behaviors. Participants had variable paths extending beyond their immediate neighborhoods, and denied that GPS-tracking influenced their activity. GPS-enabled cell phones offer a feasible and, in many ways, ideal modality of monitoring the location and travel patterns of adolescents. In addition, cell phones allow space- and time-specific interaction, probing, and intervention which significantly extends both research and health promotion beyond a clinical setting. Future studies can employ GPS-enabled cell phones to better understand adolescent environments, how they are associated with health-risk behaviors, and perhaps intervene to change health behavior.

Using GPS-enabled cell phones to track the travel patterns of adolescents

PubMed Central

Wiehe, Sarah E; Carroll, Aaron E; Liu, Gilbert C; Haberkorn, Kelly L; Hoch, Shawn C; Wilson, Jeffery S; Fortenberry, J Dennis

2008-01-01

Background Few tools exist to directly measure the microsocial and physical environments of adolescents in circumstances where participatory observation is not practical or ethical. Yet measuring these environments is important as they are significantly associated with adolescent health-risk. For example, health-related behaviors such as cigarette smoking often occur in specific places where smoking may be relatively surreptitious. Results We assessed the feasibility of using GPS-enabled cell phones to track adolescent travel patterns and gather daily diary data. We enrolled 15 adolescent women from a clinic-based setting and asked them to carry the phones for 1 week. We found that these phones can accurately and reliably track participant locations, as well as record diary information on adolescent behaviors. Participants had variable paths extending beyond their immediate neighborhoods, and denied that GPS-tracking influenced their activity. Conclusion GPS-enabled cell phones offer a feasible and, in many ways, ideal modality of monitoring the location and travel patterns of adolescents. In addition, cell phones allow space- and time-specific interaction, probing, and intervention which significantly extends both research and health promotion beyond a clinical setting. Future studies can employ GPS-enabled cell phones to better understand adolescent environments, how they are associated with health-risk behaviors, and perhaps intervene to change health behavior. PMID:18495025

Reaching rural women: breast cancer prevention information seeking behaviors and interest in Internet, cell phone, and text use.

PubMed

Kratzke, Cynthia; Wilson, Susan; Vilchis, Hugo

2013-02-01

The purpose of this study was to examine the breast cancer prevention information seeking behaviors among rural women, the prevalence of Internet, cell, and text use, and interest to receive breast cancer prevention information cell and text messages. While growing literature for breast cancer information sources supports the use of the Internet, little is known about breast cancer prevention information seeking behaviors among rural women and mobile technology. Using a cross-sectional study design, data were collected using a survey. McGuire's Input-Ouput Model was used as the framework. Self-reported data were obtained from a convenience sample of 157 women with a mean age of 60 (SD = 12.12) at a rural New Mexico imaging center. Common interpersonal information sources were doctors, nurses, and friends and common channel information sources were television, magazines, and Internet. Overall, 87% used cell phones, 20% had an interest to receive cell phone breast cancer prevention messages, 47% used text messaging, 36% had an interest to receive text breast cancer prevention messages, and 37% had an interest to receive mammogram reminder text messages. Bivariate analysis revealed significant differences between age, income, and race/ethnicity and use of cell phones or text messaging. There were no differences between age and receiving text messages or text mammogram reminders. Assessment of health information seeking behaviors is important for community health educators to target populations for program development. Future research may identify additional socio-cultural differences.

Differential Effects of Tissue Culture Coating Substrates on Prostate Cancer Cell Adherence, Morphology and Behavior

PubMed Central

Liberio, Michelle S.; Sadowski, Martin C.; Soekmadji, Carolina; Davis, Rohan A.; Nelson, Colleen C.

2014-01-01

Weak cell-surface adhesion of cell lines to tissue culture surfaces is a common problem and presents technical limitations to the design of experiments. To overcome this problem, various surface coating protocols have been developed. However, a comparative and precise real-time measurement of their impact on cell behavior has not been conducted. The prostate cancer cell line LNCaP, derived from a patient lymph node metastasis, is a commonly used model system in prostate cancer research. However, the cells’ characteristically weak attachment to the surface of tissue culture vessels and cover slips has impeded their manipulation and analysis and use in high throughput screening. To improve the adherence of LNCaP cells to the culture surface, we compared different coating reagents (poly-l-lysine, poly-l-ornithine, collagen type IV, fibronectin, and laminin) and culturing conditions and analyzed their impact on cell proliferation, adhesion, morphology, mobility and gene expression using real-time technologies. The results showed that fibronectin, poly-l-lysine and poly-l-ornithine improved LNCaP cells adherence and provoked cell morphology alterations, such as increase of nuclear and cellular area. These coating reagents also induced a higher expression of F-actin and reduced cell mobility. In contrast, laminin and collagen type IV did not improve adherence but promoted cell aggregation and affected cell morphology. Cells cultured in the presence of laminin displayed higher mobility than control cells. All the coating conditions significantly affected cell viability; however, they did not affect the expression of androgen receptor-regulated genes. Our comparative findings provide important insight for the selection of the ideal coating reagent and culture conditions for the cancer cell lines with respect to their effect on proliferation rate, attachment, morphology, migration, transcriptional response and cellular cytoskeleton arrangement. PMID:25375165

Interleukin-6, Produced by Resident Cells of the Central Nervous System and Infiltrating Cells, Contributes to the Development of Seizures following Viral Infection▿

PubMed Central

Libbey, Jane E.; Kennett, Nikki J.; Wilcox, Karen S.; White, H. Steve; Fujinami, Robert S.

2011-01-01

Cells that can participate in an innate immune response within the central nervous system (CNS) include infiltrating cells (polymorphonuclear leukocytes [PMNs], macrophages, and natural killer [NK] cells) and resident cells (microglia and sometimes astrocytes). The proinflammatory cytokine interleukin-6 (IL-6) is produced by all of these cells and has been implicated in the development of behavioral seizures in the Theiler's murine encephalomyelitis virus (TMEV)-induced seizure model. The assessment, via PCR arrays, of the mRNA expression levels of a large number of chemokines (ligands and receptors) in TMEV-infected and mock-infected C57BL/6 mice both with and without seizures did not clearly demonstrate the involvement of PMNs, monocytes/macrophages, or NK cells in the development of seizures, possibly due to overlapping function of the chemokines. Additionally, C57BL/6 mice unable to recruit or depleted of infiltrating PMNs and NK cells had seizure rates comparable to those of controls following TMEV infection, and therefore PMNs and NK cells do not significantly contribute to seizure development. In contrast, C57BL/6 mice treated with minocycline, which affects monocytes/macrophages, microglial cells, and PMNs, had significantly fewer seizures than controls following TMEV infection, indicating monocytes/macrophages and resident microglial cells are important in seizure development. Irradiated bone marrow chimeric mice that were either IL-6-deficient mice reconstituted with wild-type bone marrow cells or wild-type mice reconstituted with IL-6-deficient bone marrow cells developed significantly fewer behavioral seizures following TMEV infection. Therefore, both resident CNS cells and infiltrating cells are necessary for seizure development. PMID:21543484

Viscoelastic Properties Measurement of Human Lymphocytes by Atomic Force Microscopy Based on Magnetic Beads Cell Isolation.

PubMed

Mi Li; Lianqing Liu; Xiubin Xiao; Ning Xi; Yuechao Wang

2016-07-01

Cell mechanics has been proved to be an effective biomarker for indicating cellular states. The advent of atomic force microscopy (AFM) provides an exciting instrument for measuring the mechanical properties of single cells. However, current AFM single-cell mechanical measurements are commonly performed on cell lines cultured in vitro which are quite different from the primary cells in the human body. Investigating the mechanical properties of primary cells from clinical environments can help us to better understand cell behaviors. Here, by combining AFM with magnetic beads cell isolation, the viscoelastic properties of human primary B lymphocytes were quantitatively measured. B lymphocytes were isolated from the peripheral blood of healthy volunteers by density gradient centrifugation and CD19 magnetic beads cell isolation. The activity and specificity of the isolated cells were confirmed by fluorescence microscopy. AFM imaging revealed the surface topography and geometric parameters of B lymphocytes. The instantaneous modulus and relaxation time of living B lymphocytes were measured by AFM indenting technique, showing that the instantaneous modulus of human normal B lymphocytes was 2-3 kPa and the relaxation times were 0.03-0.06 s and 0.35-0.55 s. The differences in cellular visocoelastic properties between primary B lymphocytes and cell lines cultured in vitro were analyzed. The study proves the capability of AFM in quantifying the viscoelastic properties of individual specific primary cells from the blood sample of clinical patients, which will improve our understanding of the behaviors of cells in the human body.

A Novel Gene Controlling the Timing of Courtship Initiation in Drosophila melanogaster

PubMed Central

Luu, Peter; Zaki, Sadaf A.; Tran, David H.; French, Rachael L.

2016-01-01

Over the past 35 years, developmental geneticists have made impressive progress toward an understanding of how genes specify morphology and function, particularly as they relate to the specification of each physical component of an organism. In the last 20 years, male courtship behavior in Drosophila melanogaster has emerged as a robust model system for the study of genetic specification of behavior. Courtship behavior is both complex and innate, and a single gene, fruitless (fru), is both necessary and sufficient for all aspects of the courtship ritual. Typically, loss of male-specific Fruitless protein function results in male flies that perform the courtship ritual incorrectly, slowly, or not at all. Here we describe a novel requirement for fru: we have identified a group of cells in which male Fru proteins are required to reduce the speed of courtship initiation. In addition, we have identified a gene, Trapped in endoderm 1 (Tre1), which is required in these cells for normal courtship and mating behavior. Tre1 encodes a G-protein-coupled receptor required for establishment of cell polarity and cell migration and has previously not been shown to be involved in courtship behavior. We describe the results of feminization of the Tre1-expressing neurons, as well as the effects on courtship behavior of mutation of Tre1. In addition, we show that Tre1 is expressed in a sexually dimorphic pattern in the central and peripheral nervous systems and investigate the role of the Tre1 cells in mate identification. PMID:26721856

Input dependent cell assembly dynamics in a model of the striatal medium spiny neuron network.

PubMed

Ponzi, Adam; Wickens, Jeff

2012-01-01

The striatal medium spiny neuron (MSN) network is sparsely connected with fairly weak GABAergic collaterals receiving an excitatory glutamatergic cortical projection. Peri-stimulus time histograms (PSTH) of MSN population response investigated in various experimental studies display strong firing rate modulations distributed throughout behavioral task epochs. In previous work we have shown by numerical simulation that sparse random networks of inhibitory spiking neurons with characteristics appropriate for UP state MSNs form cell assemblies which fire together coherently in sequences on long behaviorally relevant timescales when the network receives a fixed pattern of constant input excitation. Here we first extend that model to the case where cortical excitation is composed of many independent noisy Poisson processes and demonstrate that cell assembly dynamics is still observed when the input is sufficiently weak. However if cortical excitation strength is increased more regularly firing and completely quiescent cells are found, which depend on the cortical stimulation. Subsequently we further extend previous work to consider what happens when the excitatory input varies as it would when the animal is engaged in behavior. We investigate how sudden switches in excitation interact with network generated patterned activity. We show that sequences of cell assembly activations can be locked to the excitatory input sequence and outline the range of parameters where this behavior is shown. Model cell population PSTH display both stimulus and temporal specificity, with large population firing rate modulations locked to elapsed time from task events. Thus the random network can generate a large diversity of temporally evolving stimulus dependent responses even though the input is fixed between switches. We suggest the MSN network is well suited to the generation of such slow coherent task dependent response which could be utilized by the animal in behavior.

Input Dependent Cell Assembly Dynamics in a Model of the Striatal Medium Spiny Neuron Network

PubMed Central

Ponzi, Adam; Wickens, Jeff

2012-01-01

The striatal medium spiny neuron (MSN) network is sparsely connected with fairly weak GABAergic collaterals receiving an excitatory glutamatergic cortical projection. Peri-stimulus time histograms (PSTH) of MSN population response investigated in various experimental studies display strong firing rate modulations distributed throughout behavioral task epochs. In previous work we have shown by numerical simulation that sparse random networks of inhibitory spiking neurons with characteristics appropriate for UP state MSNs form cell assemblies which fire together coherently in sequences on long behaviorally relevant timescales when the network receives a fixed pattern of constant input excitation. Here we first extend that model to the case where cortical excitation is composed of many independent noisy Poisson processes and demonstrate that cell assembly dynamics is still observed when the input is sufficiently weak. However if cortical excitation strength is increased more regularly firing and completely quiescent cells are found, which depend on the cortical stimulation. Subsequently we further extend previous work to consider what happens when the excitatory input varies as it would when the animal is engaged in behavior. We investigate how sudden switches in excitation interact with network generated patterned activity. We show that sequences of cell assembly activations can be locked to the excitatory input sequence and outline the range of parameters where this behavior is shown. Model cell population PSTH display both stimulus and temporal specificity, with large population firing rate modulations locked to elapsed time from task events. Thus the random network can generate a large diversity of temporally evolving stimulus dependent responses even though the input is fixed between switches. We suggest the MSN network is well suited to the generation of such slow coherent task dependent response which could be utilized by the animal in behavior. PMID:22438838

The advection of microparticles, MCF-7 and MDA-MB-231 breast cancer cells in response to very low Reynolds numbers.

PubMed

Morley, Sinéad T; Walsh, Michael T; Newport, David T

2017-05-01

The lymphatic system is an extensive vascular network that serves as the primary route for the metastatic spread of breast cancer cells (BCCs). The dynamics by which BCCs travel in the lymphatics to distant sites, and eventually establish metastatic tumors, remain poorly understood. Particle tracking techniques were employed to analyze the behavior of MCF-7 and MDA-MB-231 BCCs which were exposed to lymphatic flow conditions in a 100  μ m square microchannel. The behavior of the BCCs was compared to rigid particles of various diameters (η = d p /H= 0.05-0.32) that have been used to simulate cell flow in lymph. Parabolic velocity profiles were recorded for all particle sizes. All particles were found to lag the fluid velocity, the larger the particle the slower its velocity relative to the local flow (5%-15% velocity lag recorded). A distinct difference between the behavior of BCCs and particles was recorded. The BCCs travelled approximately 40% slower than the undisturbed flow, indicating that morphology and size affects their response to lymphatic flow conditions ( Re <  1). BCCs adhered together, forming aggregates whose behavior was irregular. At lymphatic flow rates, MCF-7s were distributed uniformly across the channel in comparison to the MDA-MB-231 cells which travelled in the central region (88% of cells found within 0.35 ≤ W ≤ 0.64), indicating that metastatic MDA-MB-231 cells are subjected to a lower range of shear stresses in vivo . This suggests that both size and deformability need to be considered when modelling BCC behavior in the lymphatics. This finding will inform the development of in vitro lymphatic flow and metastasis models.

Cell Adhesions: Actin-Based Modules that Mediate Cell-Extracellular Matrix and Cell-Cell Interactions

PubMed Central

Bachir, Alexia; Horwitz, Alan Rick; Nelson, W. James; Bianchini, Julie M.

2018-01-01

Cell adhesions link cells to the extracellular matrix (ECM) and to each other, and depend on interactions with the actin cytoskeleton. Both cell-ECM and cell-cell adhesion sites contain discrete, yet overlapping functional modules. These modules establish physical association with the actin cytoskeleton, locally modulate actin organization and dynamics, and trigger intracellular signaling pathways. Interplay between these modules generates distinct actin architectures that underlie different stages, types, and functions of cell-ECM and cell-cell adhesions. Actomyosin contractility is required to generate mature, stable adhesions, as well as sense and translate the mechanical properties of the cellular environment to changes in cell organization and behavior. In this chapter we discuss the organization and function of different adhesion modules and how they interact with the actin cytoskeleton. We highlight the molecular mechanisms of mechanotransduction in adhesions, and how adhesion molecules mediate crosstalk between cell-ECM and cell-cell adhesion sites. PMID:28679638

Maintenance and induction of murine embryonic stem cell differentiation using E-cadherin-Fc substrata without colony formation

NASA Astrophysics Data System (ADS)

Meng, Qing-Yuan; Akaike, Toshihiro

2013-03-01

Induced embryonic stem (ES) cells are expected to be promising cell resources for the observation of the cell behaviors in developmental biology as well as the implantation in cell treatments in human diseases. A recombinant E-cadherin substratum was developed as a cell recognizable substratum to maintain the ES cells' self-renewal and pluripotency at single cell level. Furthermore, the generation of various cell lineages in different germ layers, including hepatic or neural cells, was achieved on the chimeric protein layer precisely and effectively. The induction and isolation of specific cell population was carried out with the enhancing effect of other artificial extracellular matrices (ECMs) in enzyme-free process. The murine ES cell-derived cells showed highly morphological similarities and functional expressions to matured hepatocytes or neural progenitor cells.

A low membrane lipid phase transition temperature is associated with a high cryotolerance of Lactobacillus delbrueckii subspecies bulgaricus CFL1.

PubMed

Gautier, J; Passot, S; Pénicaud, C; Guillemin, H; Cenard, S; Lieben, P; Fonseca, F

2013-09-01

The mechanisms of cellular damage that lactic acid bacteria incur during freeze-thaw processes have not been elucidated to date. Fourier transform infrared spectroscopy was used to investigate in situ the lipid phase transition behavior of the membrane of Lactobacillus delbrueckii ssp. bulgaricus CFL1 cells during the freeze-thaw process. Our objective was to relate the lipid membrane behavior to membrane integrity losses during freezing and to cell-freezing resistance. Cells were produced by using 2 different culture media: de Man, Rogosa, and Sharpe (MRS) broth (complex medium) or mild whey-based medium (minimal medium commonly used in the dairy industry), to obtain different membrane lipid compositions corresponding to different recovery rates of cell viability and functionality after freezing. The lipid membrane behavior studied by Fourier transform infrared spectroscopy was found to be different according to the cell lipid composition and cryotolerance. Freeze-resistant cells, exhibiting a higher content of unsaturated and cyclic fatty acids, presented a lower lipid phase transition temperature (Ts) during freezing (Ts=-8°C), occurring within the same temperature range as the ice nucleation, than freeze-sensitive cells (Ts=+22°C). A subzero value of lipid phase transition allowed the maintenance of the cell membrane in a relatively fluid state during freezing, thus facilitating water flux from the cell and the concomitant volume reduction following ice formation in the extracellular medium. In addition, the lipid phase transition of freeze-resistant cells occurred within a short temperature range, which could be ascribed to a reduced number of fatty acids, representing more than 80% of the total. This short lipid phase transition could be associated with a limited phenomenon of lateral phase separation and membrane permeabilization. This work highlights that membrane phase transitions occurring during freeze-thawing play a fundamental role in the cryotolerance of Lb. delbrueckii ssp. bulgaricus CFL1 cells. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Advances in the theory and application of BSF cells. [Back Surface Field solar cells

NASA Technical Reports Server (NTRS)

Mandelkorn, J.; Lamneck, J. H.

1975-01-01

A study to determine the influence of fabrication processes and bulk material properties on the behavior of back surface field (BSF) cells is reported. It is concluded that a photovoltage is generated at the p(+), p back junction of the cell. The concept of majority carrier collection is proposed as a possible mechanism for this generation. Advantages accruing to the advent of BSF cells are outlined.

Discovery of a New Cellular Motion and Its Relevance to Breast Cancer and Involution

DTIC Science & Technology

2014-02-01

motion (CAMo), live cell imaging , confocal microscopy Overall Project Summary: During this first year of funding we have concentrated our work to...cell types in 3D cultures and in vivo. Subtask 1.1a: Real time live cell imaging using confocal microscopy will be used to image cellular movement...exciting as they are important steps in understanding behavior of normal myoepithelial cells using live cell imaging in physiologically

Microbial cell surface characteristics: Elucidating attachment/detachment using hydrophobicity and electrokinetic measurements

EPA Science Inventory

The surface properties of microorganisms play an important role in their behavior within the environment. Electrophoretic mobility and cell surface hydrophobicity of bacterial cells influence their initial interaction with surfaces and mediate their stability within an aqueous su...

YAP-dependent Mechanotransduction is Required for Proliferation and Migration on Native-like Substrate Topography

PubMed Central

Mascharak, Shamik; Benitez, Patrick L.; Proctor, Amy C.; Madl, Christopher M.; Hu, Kenneth H.; Dewi, Ruby E.; Butte, Manish J.; Heilshorn, Sarah C.

2017-01-01

Native vascular extracellular matrices (vECM) consist of elastic fibers that impart varied topographical properties, yet most in vitro models designed to study the effects of topography on cell behavior are not representative of native architecture. Here, we engineer an electrospun elastin-like protein (ELP) system with independently tunable, vECM-mimetic topography and demonstrate that increasing topographical variation causes loss of endothelial cell-cell junction organization. This loss of VE-cadherin signaling and increased cytoskeletal contractility on more topographically varied ELP substrates in turn promote YAP activation and nuclear translocation, resulting in significantly increased endothelial cell migration and proliferation. Our findings identify YAP as a required signaling factor through which fibrous substrate topography influences cell behavior and highlights topography as a key design parameter for engineered biomaterials. PMID:27889666

Magnolol causes alterations in the cell cycle in androgen insensitive human prostate cancer cells in vitro by affecting expression of key cell cycle regulatory proteins.

PubMed

McKeown, Brendan T; McDougall, Luke; Catalli, Adriana; Hurta, Robert A R

2014-01-01

Prostate cancer, one of the most common cancers in the Western world, affects many men worldwide. This study investigated the effects of magnolol, a compound found in the roots and bark of the magnolia tree Magnolia officinalis, on the behavior of 2 androgen insensitive human prostate cancer cell lines, DU145 and PC3, in vitro. Magnolol, in a 24-h exposure at 40 and 80 μM, was found to be cytotoxic to cells. Magnolol also affected cell cycle progression of DU145 and PC3 cells, resulting in alterations to the cell cycle and subsequently decreasing the proportion of cells entering the G2/M-phase of the cell cycle. Magnolol inhibited the expression of cell cycle regulatory proteins including cyclins A, B1, D1, and E, as well as CDK2 and CDK4. Protein expression levels of pRBp107 decreased and pRBp130 protein expression levels increased in response to magnolol exposure, whereas p16(INK4a), p21, and p27 protein expression levels were apparently unchanged post 24-h exposure. Magnolol exposure at 6 h did increase p27 protein expression levels. This study has demonstrated that magnolol can alter the behavior of androgen insensitive human prostate cancer cells in vitro and suggests that magnolol may have potential as a novel anti-prostate cancer agent.

Perception of noxious compounds by contact chemoreceptors of the blowfly, Phormia regina: putative role of an odorant-bindingpProtein.

PubMed

Ozaki, Mamiko; Takahara, Teruhiko; Kawahara, Yasuhiro; Wada-Katsumata, Ayako; Seno, Keiji; Amakawa, Taisaku; Yamaoka, Ryohei; Nakamura, Tadashi

2003-05-01

The blowfly, Phormia regina, has sensilla with four contact-chemoreceptor cells and one mechanoreceptor cell on its labellum. Three of the four chemoreceptor cells are called the sugar, the salt and the water receptor cells, respectively. However, the specificity of the remaining chemoreceptor cell, traditionally called the "fifth cell", has not yet been clarified. Referring to behavioral evaluation of the oral toxicity of monoterpenes, we measured the electrophysiological response of the "fifth cell" to these compounds. Of all the monoterpenes examined, D-limonene exhibited the strongest oral toxicity and induced the severest aversive behavior with vomiting and/or excretion in the fly. D-Limonene, when dispersed in an aqueous stimulus solution including dimethyl sulfoxide or an odorant-binding protein (OBP) found in the contact-chemoreceptor sensillum, the chemical sense-related lipophilic ligand-binding protein (CRLBP), evoked impulses from the "fifth cell". Considering the relationship between the aversive effects of monoterpenes and the response of the "fifth cell" to these effects, we propose that the "fifth cell" is a warning cell that has been differentiated as a taste system for detecting and avoiding dangerous foods. Here we suggest that in the insect contact-chemoreceptor sensillum, CRLBP carries lipophilic members of the noxious taste substances to the "fifth cell" through the aqueous sensillum lymph. This insect OBP may functionally be analogous to the von Ebner's grand protein in taste organs of mammals.

Regulation of adipose-tissue-derived stromal cell orientation and motility in 2D- and 3D-cultures by direct-current electrical field.

PubMed

Yang, Gang; Long, Haiyan; Ren, Xiaomei; Ma, Kunlong; Xiao, Zhenghua; Wang, Ying; Guo, Yingqiang

2017-02-01

Cell alignment and motility play a critical role in a variety of cell behaviors, including cytoskeleton reorganization, membrane-protein relocation, nuclear gene expression, and extracellular matrix remodeling. Direct current electric field (EF) in vitro can direct many types of cells to align vertically to EF vector. In this work, we investigated the effects of EF stimulation on rat adipose-tissue-derived stromal cells (ADSCs) in 2D-culture on plastic culture dishes and in 3D-culture on various scaffold materials, including collagen hydrogels, chitosan hydrogels and poly(L-lactic acid)/gelatin electrospinning fibers. Rat ADSCs were exposed to various physiological-strength EFs in a homemade EF-bioreactor. Changes of morphology and movements of cells affected by applied EFs were evaluated by time-lapse microphotography, and cell survival rates and intracellular calcium oscillations were also detected. Results showed that EF facilitated ADSC morphological changes, under 6 V/cm EF strength, and that ADSCs in 2D-culture aligned vertically to EF vector and kept a good cell survival rate. In 3D-culture, cell galvanotaxis responses were subject to the synergistic effect of applied EF and scaffold materials. Fast cell movement and intracellular calcium activities were observed in the cells of 3D-culture. We believe our research will provide some experimental references for the future study in cell galvanotaxis behaviors. © 2017 Japanese Society of Developmental Biologists.

The Use of Intravital Two-Photon and Thick Section Confocal Imaging to Analyze B Lymphocyte Trafficking in Lymph Nodes and Spleen.

PubMed

Park, Chung; Hwang, Il-Young; Kehrl, John H

2018-01-01

Intravital two-photon laser scanning microscopy (TP-LSM) has allowed the direct observation of immune cells in intact organs of living animals. In the B cell biology field TP-LSM has detailed the movement of B cells in high endothelial venules and during their transmigration into lymph organs; described the movement and positioning of B cells within lymphoid organs; outlined the mechanisms by which antigen is delivered to B cells; observed B cell interacting with T cells, other cell types, and even with pathogens; and delineated the egress of B cells from the lymph node (LN) parenchyma into the efferent lymphatics. As the quality of TP-LSM improves and as new fluorescent probes become available additional insights into B cell behavior and function await new investigations. Yet intravital TP-LSM has some disadvantages including a lower resolution than standard confocal microscopy, a narrow imaging window, and a shallow depth of imaging. We have found that supplementing intravital TP-LSM with conventional confocal microscopy using thick LN sections helps to overcome some of these shortcomings. Here, we describe procedures for visualizing the behavior and trafficking of fluorescently labeled, adoptively transferred antigen-activated B cells within the inguinal LN of live mice using two-photon microscopy. Also, we introduce procedures for fixed thick section imaging using standard confocal microscopy, which allows imaging of fluorescently labeled cells deep in the LN cortex and in the spleen with high resolution.

Self-Monitoring with a Twist: Using Cell Phones to CellF-Monitor On-Task Behavior

ERIC Educational Resources Information Center

Bedesem, Peña L.; Dieker, Lisa A.

2014-01-01

Self-monitoring is regarded throughout the literature as an effective classroom intervention. Researchers have used self-monitoring interventions to improve school-related behavior of students with varying disabilities across a variety of settings. Although research supports the use of self-monitoring, traditional self-monitoring techniques may be…

In Search of Cellular Immunophenotypes in the Blood of Children with Autism

PubMed Central

Ashwood, Paul; Corbett, Blythe A.; Kantor, Aaron; Schulman, Howard; Van de Water, Judy; Amaral, David G.

2011-01-01

Background Autism is a neurodevelopmental disorder characterized by impairments in social behavior, communication difficulties and the occurrence of repetitive or stereotyped behaviors. There has been substantial evidence for dysregulation of the immune system in autism. Methods We evaluated differences in the number and phenotype of circulating blood cells in young children with autism (n = 70) compared with age-matched controls (n = 35). Children with a confirmed diagnosis of autism (4–6 years of age) were further subdivided into low (IQ<68, n = 35) or high functioning (IQ≥68, n = 35) groups. Age- and gender-matched typically developing children constituted the control group. Six hundred and forty four primary and secondary variables, including cell counts and the abundance of cell surface antigens, were assessed using microvolume laser scanning cytometry. Results There were multiple differences in immune cell populations between the autism and control groups. The absolute number of B cells per volume of blood was over 20% higher for children with autism and the absolute number of NK cells was about 40% higher. Neither of these variables showed significant difference between the low and high functioning autism groups. While the absolute number of T cells was not different across groups, a number of cellular activation markers, including HLA-DR and CD26 on T cells, and CD38 on B cells, were significantly higher in the autism group compared to controls. Conclusions These results support previous findings that immune dysfunction may occur in some children with autism. Further evaluation of the nature of the dysfunction and how it may play a role in the etiology of autism or in facets of autism neuropathology and/or behavior are needed. PMID:21573236