Efficient Direct Lineage Reprogramming of Fibroblasts into Induced Cardiomyocytes Using Nanotopographical Cues.

PubMed

Yoo, Junsang; Chang, Yujung; Kim, Hongwon; Baek, Soonbong; Choi, Hwan; Jeong, Gun-Jae; Shin, Jaein; Kim, Hongnam; Kim, Byung-Soo; Kim, Jongpil

2017-03-01

Induced cardiomyocytes (iCMs) generated via direct lineage reprogramming offer a novel therapeutic target for the study and treatment of cardiac diseases. However, the efficiency of iCM generation is significantly low for therapeutic applications. Here, we show an efficient direct conversion of somatic fibroblasts into iCMs using nanotopographic cues. Compared with flat substrates, the direct conversion of fibroblasts into iCMs on nanopatterned substrates resulted in a dramatic increase in the reprogramming efficiency and maturation of iCM phenotypes. Additionally, enhanced reprogramming by substrate nanotopography was due to changes in the activation of focal adhesion kinase and specific histone modifications. Taken together, these results suggest that nanotopographic cues can serve as an efficient stimulant for direct lineage reprogramming into iCMs.

3D in vitro co-culture models based on normal cells and tumor spheroids formed by cyclic RGD-peptide induced cell self-assembly.

PubMed

Akasov, Roman; Gileva, Anastasia; Zaytseva-Zotova, Daria; Burov, Sergey; Chevalot, Isabelle; Guedon, Emmanuel; Markvicheva, Elena

2017-01-01

To design novel 3D in vitro co-culture models based on the RGD-peptide-induced cell self-assembly technique. Multicellular spheroids from M-3 murine melanoma cells and L-929 murine fibroblasts were obtained directly from monolayer culture by addition of culture medium containing cyclic RGD-peptide. To reach reproducible architecture of co-culture spheroids, two novel 3D in vitro models with well pronounced core-shell structure from tumor spheroids and single mouse fibroblasts were developed based on this approach. The first was a combination of a RGD-peptide platform with the liquid overlay technique with further co-cultivation for 1-2 days. The second allowed co-culture spheroids to generate within polyelectrolyte microcapsules by cultivation for 2 weeks. M-3 cells (a core) and L-929 fibroblasts (a shell) were easily distinguished by confocal microscopy due to cell staining with DiO and DiI dyes, respectively. The 3D co-culture spheroids are proposed as a tool in tumor biology to study cell-cell interactions as well as for testing novel anticancer drugs and drug delivery vehicles.

The origin of multicellularity in cyanobacteria

PubMed Central

2011-01-01

Background Cyanobacteria are one of the oldest and morphologically most diverse prokaryotic phyla on our planet. The early development of an oxygen-containing atmosphere approximately 2.45 - 2.22 billion years ago is attributed to the photosynthetic activity of cyanobacteria. Furthermore, they are one of the few prokaryotic phyla where multicellularity has evolved. Understanding when and how multicellularity evolved in these ancient organisms would provide fundamental information on the early history of life and further our knowledge of complex life forms. Results We conducted and compared phylogenetic analyses of 16S rDNA sequences from a large sample of taxa representing the morphological and genetic diversity of cyanobacteria. We reconstructed ancestral character states on 10,000 phylogenetic trees. The results suggest that the majority of extant cyanobacteria descend from multicellular ancestors. Reversals to unicellularity occurred at least 5 times. Multicellularity was established again at least once within a single-celled clade. Comparison to the fossil record supports an early origin of multicellularity, possibly as early as the "Great Oxygenation Event" that occurred 2.45 - 2.22 billion years ago. Conclusions The results indicate that a multicellular morphotype evolved early in the cyanobacterial lineage and was regained at least once after a previous loss. Most of the morphological diversity exhibited in cyanobacteria today —including the majority of single-celled species— arose from ancient multicellular lineages. Multicellularity could have conferred a considerable advantage for exploring new niches and hence facilitated the diversification of new lineages. PMID:21320320

NADPH oxidase: an enzyme for multicellularity?

PubMed

Lalucque, Hervé; Silar, Philippe

2003-01-01

Multicellularity has evolved several times during the evolution of eukaryotes. One evolutionary pressure that permits multicellularity relates to the division of work, where one group of cells functions as nutrient providers and the other in specialized roles such as defence or reproduction. This requires signalling systems to ensure harmonious development of multicellular structures. Here, we show that NADPH oxidases are specifically present in organisms that differentiate multicellular structures during their life cycle and are absent from unicellular life forms. The biochemical properties of these enzymes make them ideal candidates for a role in intercellular signalling.

The Multiple Origins of Complex Multicellularity

NASA Astrophysics Data System (ADS)

Knoll, Andrew H.

2011-05-01

Simple multicellularity has evolved numerous times within the Eukarya, but complex multicellular organisms belong to only six clades: animals, embryophytic land plants, florideophyte red algae, laminarialean brown algae, and two groups of fungi. Phylogeny and genomics suggest a generalized trajectory for the evolution of complex multicellularity, beginning with the co-optation of existing genes for adhesion. Molecular channels to facilitate cell-cell transfer of nutrients and signaling molecules appear to be critical, as this trait occurs in all complex multicellular organisms but few others. Proliferation of gene families for transcription factors and cell signals accompany the key functional innovation of complex multicellular clades: differentiated cells and tissues for the bulk transport of oxygen, nutrients, and molecular signals that enable organisms to circumvent the physical limitations of diffusion. The fossil records of animals and plants document key stages of this trajectory.

Cancer-associated fibroblasts promote directional cancer cell migration by aligning fibronectin.

PubMed

Erdogan, Begum; Ao, Mingfang; White, Lauren M; Means, Anna L; Brewer, Bryson M; Yang, Lijie; Washington, M Kay; Shi, Chanjuan; Franco, Omar E; Weaver, Alissa M; Hayward, Simon W; Li, Deyu; Webb, Donna J

2017-11-06

Cancer-associated fibroblasts (CAFs) are major components of the carcinoma microenvironment that promote tumor progression. However, the mechanisms by which CAFs regulate cancer cell migration are poorly understood. In this study, we show that fibronectin (Fn) assembled by CAFs mediates CAF-cancer cell association and directional migration. Compared with normal fibroblasts, CAFs produce an Fn-rich extracellular matrix with anisotropic fiber orientation, which guides the cancer cells to migrate directionally. CAFs align the Fn matrix by increasing nonmuscle myosin II- and platelet-derived growth factor receptor α-mediated contractility and traction forces, which are transduced to Fn through α5β1 integrin. We further show that prostate cancer cells use αv integrin to migrate efficiently and directionally on CAF-derived matrices. We demonstrate that aligned Fn is a prominent feature of invasion sites in human prostatic and pancreatic carcinoma samples. Collectively, we present a new mechanism by which CAFs organize the Fn matrix and promote directional cancer cell migration. © 2017 Erdogan et al.

Cancer-associated fibroblasts promote directional cancer cell migration by aligning fibronectin

PubMed Central

Ao, Mingfang; White, Lauren M.; Means, Anna L.; Yang, Lijie; Washington, M. Kay; Franco, Omar E.; Li, Deyu; Webb, Donna J.

2017-01-01

Cancer-associated fibroblasts (CAFs) are major components of the carcinoma microenvironment that promote tumor progression. However, the mechanisms by which CAFs regulate cancer cell migration are poorly understood. In this study, we show that fibronectin (Fn) assembled by CAFs mediates CAF–cancer cell association and directional migration. Compared with normal fibroblasts, CAFs produce an Fn-rich extracellular matrix with anisotropic fiber orientation, which guides the cancer cells to migrate directionally. CAFs align the Fn matrix by increasing nonmuscle myosin II- and platelet-derived growth factor receptor α–mediated contractility and traction forces, which are transduced to Fn through α5β1 integrin. We further show that prostate cancer cells use αv integrin to migrate efficiently and directionally on CAF-derived matrices. We demonstrate that aligned Fn is a prominent feature of invasion sites in human prostatic and pancreatic carcinoma samples. Collectively, we present a new mechanism by which CAFs organize the Fn matrix and promote directional cancer cell migration. PMID:29021221

Experimental evolution reveals that high relatedness protects multicellular cooperation from cheaters

PubMed Central

Bastiaans, Eric; Debets, Alfons J. M.; Aanen, Duur K.

2016-01-01

In multicellular organisms, there is a potential risk that cheating mutants gain access to the germline. Development from a single-celled zygote resets relatedness among cells to its maximum value each generation, which should accomplish segregation of cheating mutants from non-cheaters and thereby protect multicellular cooperation. Here we provide the crucial direct comparison between high- and low-relatedness conditions to test this hypothesis. We allow two variants of the fungus Neurospora crassa to evolve, one with and one without the ability to form chimeras with other individuals, thus generating two relatedness levels. While multicellular cooperation remains high in the high-relatedness lines, it significantly decreases in all replicate low-relatedness lines, resulting in an average threefold decrease in spore yield. This reduction is caused by cheating mutants with reduced investment in somatic functions, but increased competitive success when fusing with non-cheaters. Our experiments demonstrate that high genetic relatedness is crucial to sustain multicellular cooperation. PMID:27139112

Microbial multicellular development: mechanical forces in action.

PubMed

Rivera-Yoshida, Natsuko; Arias Del Angel, Juan A; Benítez, Mariana

2018-06-06

Multicellular development occurs in diverse microbial lineages and involves the complex interaction among biochemical, physical and ecological factors. We focus on the mechanical forces that appear to be relevant for the scale and material qualities of individual cells and small cellular conglomerates. We review the effects of such forces on the development of some paradigmatic microorganisms, as well as their overall consequences in multicellular structures. Microbes exhibiting multicellular development have been considered models for the evolutionary transition to multicellularity. Therefore, we discuss how comparative, integrative and dynamic approaches to the mechanical effects involved in microbial development can provide valuable insights into some of the principles behind the evolutionary transition to multicellularity. Copyright © 2018 Elsevier Ltd. All rights reserved.

Directed fusion of cardiac spheroids into larger heterocellular microtissues enables investigation of cardiac action potential propagation via cardiac fibroblasts

PubMed Central

Markes, Alexander R.; Okundaye, Amenawon O.; Qu, Zhilin; Mende, Ulrike; Choi, Bum-Rak

2018-01-01

Multicellular spheroids generated through cellular self-assembly provide cytoarchitectural complexities of native tissue including three-dimensionality, extensive cell-cell contacts, and appropriate cell-extracellular matrix interactions. They are increasingly suggested as building blocks for larger engineered tissues to achieve shapes, organization, heterogeneity, and other biomimetic complexities. Application of these tissue culture platforms is of particular importance in cardiac research as the myocardium is comprised of distinct but intermingled cell types. Here, we generated scaffold-free 3D cardiac microtissue spheroids comprised of cardiac myocytes (CMs) and/or cardiac fibroblasts (CFs) and used them as building blocks to form larger microtissues with different spatial distributions of CMs and CFs. Characterization of fusing homotypic and heterotypic spheroid pairs revealed an important influence of CFs on fusion kinetics, but most strikingly showed rapid fusion kinetics between heterotypic pairs consisting of one CF and one CM spheroid, indicating that CMs and CFs self-sort in vitro into the intermixed morphology found in the healthy myocardium. We then examined electrophysiological integration of fused homotypic and heterotypic microtissues by mapping action potential propagation. Heterocellular elongated microtissues which recapitulate the disproportionate CF spatial distribution seen in the infarcted myocardium showed that action potentials propagate through CF volumes albeit with significant delay. Complementary computational modeling revealed an important role of CF sodium currents and the spatial distribution of the CM-CF boundary in action potential conduction through CF volumes. Taken together, this study provides useful insights for the development of complex, heterocellular engineered 3D tissue constructs and their engraftment via tissue fusion and has implications for arrhythmogenesis in cardiac disease and repair. PMID:29715271

Peptide-enhanced mRNA transfection in cultured mouse cardiac fibroblasts and direct reprogramming towards cardiomyocyte-like cells

PubMed Central

Lee, Kunwoo; Yu, Pengzhi; Lingampalli, Nithya; Kim, Hyun Jin; Tang, Richard; Murthy, Niren

2015-01-01

The treatment of myocardial infarction is a major challenge in medicine due to the inability of heart tissue to regenerate. Direct reprogramming of endogenous cardiac fibroblasts into functional cardiomyocytes via the delivery of transcription factor mRNAs has the potential to regenerate cardiac tissue and to treat heart failure. Even though mRNA delivery to cardiac fibroblasts has the therapeutic potential, mRNA transfection in cardiac fibroblasts has been challenging. Herein, we develop an efficient mRNA transfection in cultured mouse cardiac fibroblasts via a polyarginine-fused heart-targeting peptide and lipofectamine complex, termed C-Lipo and demonstrate the partial direct reprogramming of cardiac fibroblasts towards cardiomyocyte cells. C-Lipo enabled the mRNA-induced direct cardiac reprogramming due to its efficient transfection with low toxicity, which allowed for multiple transfections of Gata4, Mef2c, and Tbx5 (GMT) mRNAs for a period of 2 weeks. The induced cardiomyocyte-like cells had α-MHC promoter-driven GFP expression and striated cardiac muscle structure from α-actinin immunohistochemistry. GMT mRNA transfection of cultured mouse cardiac fibroblasts via C-Lipo significantly increased expression of the cardiomyocyte marker genes, Actc1, Actn2, Gja1, Hand2, and Tnnt2, after 2 weeks of transfection. Moreover, this study provides the first direct evidence that the stoichiometry of the GMT reprogramming factors influence the expression of cardiomyocyte marker genes. Our results demonstrate that mRNA delivery is a potential approach for cardiomyocyte generation. PMID:25834424

Quiescent Fibroblasts Exhibit High Metabolic Activity

PubMed Central

Lemons, Johanna M. S.; Feng, Xiao-Jiang; Bennett, Bryson D.; Legesse-Miller, Aster; Johnson, Elizabeth L.; Raitman, Irene; Pollina, Elizabeth A.; Rabitz, Herschel A.; Rabinowitz, Joshua D.; Coller, Hilary A.

2010-01-01

Many cells in mammals exist in the state of quiescence, which is characterized by reversible exit from the cell cycle. Quiescent cells are widely reported to exhibit reduced size, nucleotide synthesis, and metabolic activity. Much lower glycolytic rates have been reported in quiescent compared with proliferating lymphocytes. In contrast, we show here that primary human fibroblasts continue to exhibit high metabolic rates when induced into quiescence via contact inhibition. By monitoring isotope labeling through metabolic pathways and quantitatively identifying fluxes from the data, we show that contact-inhibited fibroblasts utilize glucose in all branches of central carbon metabolism at rates similar to those of proliferating cells, with greater overflow flux from the pentose phosphate pathway back to glycolysis. Inhibition of the pentose phosphate pathway resulted in apoptosis preferentially in quiescent fibroblasts. By feeding the cells labeled glutamine, we also detected a “backwards” flux in the tricarboxylic acid cycle from α-ketoglutarate to citrate that was enhanced in contact-inhibited fibroblasts; this flux likely contributes to shuttling of NADPH from the mitochondrion to cytosol for redox defense or fatty acid synthesis. The high metabolic activity of the fibroblasts was directed in part toward breakdown and resynthesis of protein and lipid, and in part toward excretion of extracellular matrix proteins. Thus, reduced metabolic activity is not a hallmark of the quiescent state. Quiescent fibroblasts, relieved of the biosynthetic requirements associated with generating progeny, direct their metabolic activity to preservation of self integrity and alternative functions beneficial to the organism as a whole. PMID:21049082

Spatial self-organization in hybrid models of multicellular adhesion

NASA Astrophysics Data System (ADS)

Bonforti, Adriano; Duran-Nebreda, Salva; Montañez, Raúl; Solé, Ricard

2016-10-01

Spatial self-organization emerges in distributed systems exhibiting local interactions when nonlinearities and the appropriate propagation of signals are at work. These kinds of phenomena can be modeled with different frameworks, typically cellular automata or reaction-diffusion systems. A different class of dynamical processes involves the correlated movement of agents over space, which can be mediated through chemotactic movement or minimization of cell-cell interaction energy. A classic example of the latter is given by the formation of spatially segregated assemblies when cells display differential adhesion. Here, we consider a new class of dynamical models, involving cell adhesion among two stochastically exchangeable cell states as a minimal model capable of exhibiting well-defined, ordered spatial patterns. Our results suggest that a whole space of pattern-forming rules is hosted by the combination of physical differential adhesion and the value of probabilities modulating cell phenotypic switching, showing that Turing-like patterns can be obtained without resorting to reaction-diffusion processes. If the model is expanded allowing cells to proliferate and die in an environment where diffusible nutrient and toxic waste are at play, different phases are observed, characterized by regularly spaced patterns. The analysis of the parameter space reveals that certain phases reach higher population levels than other modes of organization. A detailed exploration of the mean-field theory is also presented. Finally, we let populations of cells with different adhesion matrices compete for reproduction, showing that, in our model, structural organization can improve the fitness of a given cell population. The implications of these results for ecological and evolutionary models of pattern formation and the emergence of multicellularity are outlined.

A microfabricated platform to form three-dimensional toroidal multicellular aggregate.

PubMed

Masuda, Taisuke; Takei, Natsuki; Nakano, Takuma; Anada, Takahisa; Suzuki, Osamu; Arai, Fumihito

2012-12-01

Techniques that allow cells to self-assemble into three-dimensional (3D) spheroid microtissues provide powerful in vitro models that are becoming increasingly popular in fields such as stem cell research, tissue engineering, and cancer biology. Appropriate simulation of the 3D environment in which tissues normally develop and function is crucial for the engineering of in vitro models that can be used for the formation of complex tissues. We have developed a unique multicellular aggregate formation platform that utilizes a maskless gray-scale photolithography. The cellular aggregate formed using this platform has a toroidal-like geometry and includes a micro lumen that facilitates the supply of oxygen and growth factors and the expulsion of waste products. As a result, this platform was capable of rapidly producing hundreds of multicellular aggregates at a time, and of regulating the diameter of aggregates with complex design. These toroidal multicellular aggregates can grow as long-term culture. In addition, the micro lumen can be used as a continuous channel and for the insertion of a vascular system or a nerve system into the assembled tissue. These platform characteristics highlight its potential to be used in a wide variety of applications, e.g. as a bioactuator, as a micro-machine component or in drug screening and tissue engineering.

Synergistic cooperation promotes multicellular performance and unicellular free-rider persistence

PubMed Central

Driscoll, William W; Travisano, Michael

2017-01-01

The evolution of multicellular life requires cooperation among cells, which can be undermined by intra-group selection for selfishness. Theory predicts that selection to avoid non-cooperators limits social interactions among non-relatives, yet previous evolution experiments suggest that intra-group conflict is an outcome, rather than a driver, of incipient multicellular life cycles. Here we report the evolution of multicellularity via two distinct mechanisms of group formation in the unicellular budding yeast Kluyveromyces lactis. Cells remain permanently attached following mitosis, giving rise to clonal clusters (staying together); clusters then reversibly assemble into social groups (coming together). Coming together amplifies the benefits of multicellularity and allows social clusters to collectively outperform solitary clusters. However, cooperation among non-relatives also permits fast-growing unicellular lineages to ‘free-ride' during selection for increased size. Cooperation and competition for the benefits of multicellularity promote the stable coexistence of unicellular and multicellular genotypes, underscoring the importance of social and ecological context during the transition to multicellularity. PMID:28580966

Origins of multicellular evolvability in snowflake yeast

PubMed Central

Ratcliff, William C.; Fankhauser, Johnathon D.; Rogers, David W.; Greig, Duncan; Travisano, Michael

2015-01-01

Complex life has arisen through a series of ‘major transitions’ in which collectives of formerly autonomous individuals evolve into a single, integrated organism. A key step in this process is the origin of higher-level evolvability, but little is known about how higher-level entities originate and gain the capacity to evolve as an individual. Here we report a single mutation that not only creates a new level of biological organization, but also potentiates higher-level evolvability. Disrupting the transcription factor ACE2 in Saccharomyces cerevisiae prevents mother–daughter cell separation, generating multicellular ‘snowflake’ yeast. Snowflake yeast develop through deterministic rules that produce geometrically defined clusters that preclude genetic conflict and display a high broad-sense heritability for multicellular traits; as a result they are preadapted to multicellular adaptation. This work demonstrates that simple microevolutionary changes can have profound macroevolutionary consequences, and suggests that the formation of clonally developing clusters may often be the first step to multicellularity. PMID:25600558

Cancer across the tree of life: cooperation and cheating in multicellularity

PubMed Central

Aktipis, C. Athena; Boddy, Amy M.; Jansen, Gunther; Hibner, Urszula; Hochberg, Michael E.; Maley, Carlo C.; Wilkinson, Gerald S.

2015-01-01

Multicellularity is characterized by cooperation among cells for the development, maintenance and reproduction of the multicellular organism. Cancer can be viewed as cheating within this cooperative multicellular system. Complex multicellularity, and the cooperation underlying it, has evolved independently multiple times. We review the existing literature on cancer and cancer-like phenomena across life, not only focusing on complex multicellularity but also reviewing cancer-like phenomena across the tree of life more broadly. We find that cancer is characterized by a breakdown of the central features of cooperation that characterize multicellularity, including cheating in proliferation inhibition, cell death, division of labour, resource allocation and extracellular environment maintenance (which we term the five foundations of multicellularity). Cheating on division of labour, exhibited by a lack of differentiation and disorganized cell masses, has been observed in all forms of multicellularity. This suggests that deregulation of differentiation is a fundamental and universal aspect of carcinogenesis that may be underappreciated in cancer biology. Understanding cancer as a breakdown of multicellular cooperation provides novel insights into cancer hallmarks and suggests a set of assays and biomarkers that can be applied across species and characterize the fundamental requirements for generating a cancer. PMID:26056363

Fibroblasts are in a position to provide directional information to migrating neutrophils during pneumonia in rabbit lungs.

PubMed

Behzad, A R; Chu, F; Walker, D C

1996-05-01

Previous findings have shown that pulmonary fibroblasts are associated with preexisting holes in the endothelial and epithelial basal laminae through which neutrophils appear to enter and leave the interstitium as they migrate from capillaries to alveoli. To determine their role in neutrophil migration, fibroblast organization within the interstitium was assessed by transmission electron microscope observations of serial-sectioned rabbit lung tissue. Interstitial fibroblasts were found to physically interconnect the endothelial basal lamina holes to epithelial basal lamina holes. Morphometric assessment of rabbit lung tissue instilled with Streptococcus pneumoniae revealed that approximately 70% of the surface area density of migrating neutrophils is in close contact (15 nm or less) with interstitial fibroblasts and extracellular matrix elements (30 and 40%, respectively). Although migrating neutrophils were close enough to adhere to both fibroblasts and extracellular elements, the interstitial fibroblasts are organized in a manner that would allow them to provide directional information to the neutrophils. A model illustrating this process is proposed.

LXA{sub 4} actions direct fibroblast function and wound closure

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

Herrera, Bruno S.; Microbiology Branch, US Army Dental and Trauma Research Detachment, Institute of Surgical Research, JBSA Fort Sam Houston, TX; Kantarci, Alpdogan

Timely resolution of inflammation is crucial for normal wound healing. Resolution of inflammation is an active biological process regulated by specialized lipid mediators including the lipoxins and resolvins. Failure of resolution activity has a major negative impact on wound healing in chronic inflammatory diseases that is manifest as excess fibrosis and scarring. Lipoxins, including Lipoxin A{sub 4} (LXA{sub 4}), have known anti-fibrotic and anti-scarring properties. The goal of this study was to elucidate the impact of LXA{sub 4} on fibroblast function. Mouse fibroblasts (3T3 Mus musculus Swiss) were cultured for 72 h in the presence of TGF-β1, to induce fibroblast activation.more » The impact of exogenous TGF-β1 (1 ng/mL) on LXA{sub 4} receptor expression (ALX/FPR2) was determined by flow cytometry. Fibroblast proliferation was measured by bromodeoxyuridine (BrdU) labeling and migration in a “scratch” assay wound model. Expression of α-smooth muscle actin (α-SMA), and collagen types I and III were measured by Western blot. We observed that TGF-β1 up-regulates LXA{sub 4} receptor expression, enhances fibroblast proliferation, migration and scratch wound closure. α-SMA levels and Collagen type I and III deposition were also enhanced. LXA{sub 4} slowed fibroblast migration and scratch wound closure at early time points (24 h), but wound closure was equal to TGF-β1 alone at 48 and 72 h. LXA{sub 4} tended to slow fibroblast proliferation at both concentrations, but had no impact on α-SMA or collagen production by TGF-β1 stimulated fibroblasts. The generalizability of the actions of resolution molecules was examined in experiments repeated with resolvin D2 (RvD2) as the agonist. The activity of RvD2 mimicked the actions of LXA{sub 4} in all assays, through an as yet unidentified receptor. The results suggest that mediators of resolution of inflammation enhance wound healing and limit fibrosis in part by modulating fibroblast function. - Highlights

Modeling tensional homeostasis in multicellular clusters.

PubMed

Tam, Sze Nok; Smith, Michael L; Stamenović, Dimitrije

2017-03-01

Homeostasis of mechanical stress in cells, or tensional homeostasis, is essential for normal physiological function of tissues and organs and is protective against disease progression, including atherosclerosis and cancer. Recent experimental studies have shown that isolated cells are not capable of maintaining tensional homeostasis, whereas multicellular clusters are, with stability increasing with the size of the clusters. Here, we proposed simple mathematical models to interpret experimental results and to obtain insight into factors that determine homeostasis. Multicellular clusters were modeled as one-dimensional arrays of linearly elastic blocks that were either jointed or disjointed. Fluctuating forces that mimicked experimentally measured cell-substrate tractions were obtained from Monte Carlo simulations. These forces were applied to the cluster models, and the corresponding stress field in the cluster was calculated by solving the equilibrium equation. It was found that temporal fluctuations of the cluster stress field became attenuated with increasing cluster size, indicating that the cluster approached tensional homeostasis. These results were consistent with previously reported experimental data. Furthermore, the models revealed that key determinants of tensional homeostasis in multicellular clusters included the cluster size, the distribution of traction forces, and mechanical coupling between adjacent cells. Based on these findings, we concluded that tensional homeostasis was a multicellular phenomenon. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Unsuccessful mitosis in multicellular tumour spheroids.

PubMed

Molla, Annie; Couvet, Morgane; Coll, Jean-Luc

2017-04-25

Multicellular spheroids are very attractive models in oncology because they mimic the 3D organization of the tumour cells with their microenvironment. We show here using 3 different cell types (mammary TSA/pc, embryonic kidney Hek293 and cervical cancer HeLa), that when the cells are growing as spheroids the frequency of binucleated cells is augmented as occurs in some human tumours.We therefore describe mitosis in multicellular spheroids by following mitotic markers and by time-lapse experiments. Chromosomes alignment appears to be correct on the metaphasic plate and the passenger complex is well localized on centromere. Moreover aurora kinases are fully active and histone H3 is phosphorylated on Ser 10. Consequently, the mitotic spindle checkpoint is satisfied and, anaphase proceeds as illustrated by the transfer of survivin on the spindle and by the segregation of the two lots of chromosomes. However, the segregation plane is not well defined and oscillations of the dividing cells are observed. Finally, cytokinesis fails and the absence of separation of the two daughter cells gives rise to binucleated cells.Division orientation is specified during interphase and persists throughout mitosis. Our data indicate that the cancer cells, in multicellular spheroids, lose their ability to regulate their orientation, a feature commonly encountered in tumours.Moreover, multicellular spheroid expansion is still sensitive to mitotic drugs as pactlitaxel and aurora kinase inhibitors. The spheroids thus represent a highly relevant model for studying drug efficiency in tumours.

Reliability analysis of multicellular system architectures for low-cost satellites

NASA Astrophysics Data System (ADS)

Erlank, A. O.; Bridges, C. P.

2018-06-01

Multicellular system architectures are proposed as a solution to the problem of low reliability currently seen amongst small, low cost satellites. In a multicellular architecture, a set of independent k-out-of-n systems mimic the cells of a biological organism. In order to be beneficial, a multicellular architecture must provide more reliability per unit of overhead than traditional forms of redundancy. The overheads include power consumption, volume and mass. This paper describes the derivation of an analytical model for predicting a multicellular system's lifetime. The performance of such architectures is compared against that of several common forms of redundancy and proven to be beneficial under certain circumstances. In addition, the problem of peripheral interfaces and cross-strapping is investigated using a purpose-developed, multicellular simulation environment. Finally, two case studies are presented based on a prototype cell implementation, which demonstrate the feasibility of the proposed architecture.

Green Algae and the Origins of Multicellularity in the Plant Kingdom

PubMed Central

Umen, James G.

2014-01-01

The green lineage of chlorophyte algae and streptophytes form a large and diverse clade with multiple independent transitions to produce multicellular and/or macroscopically complex organization. In this review, I focus on two of the best-studied multicellular groups of green algae: charophytes and volvocines. Charophyte algae are the closest relatives of land plants and encompass the transition from unicellularity to simple multicellularity. Many of the innovations present in land plants have their roots in the cell and developmental biology of charophyte algae. Volvocine algae evolved an independent route to multicellularity that is captured by a graded series of increasing cell-type specialization and developmental complexity. The study of volvocine algae has provided unprecedented insights into the innovations required to achieve multicellularity. PMID:25324214

Self Directed Learning and Self Management. Symposium.

ERIC Educational Resources Information Center

2002

This document contains three papers from a symposium on self-directed learning and self-management. "Validating a More-Dimensional Conception of Self-Directed Learning" (Gerald A. Straka, Cornelia Schaefer) discusses the development and validation of a conception of self-directed learning as a dynamic interplay between behavior,…

Multiscale modeling of the dynamics of multicellular systems

NASA Astrophysics Data System (ADS)

Kosztin, Ioan

2011-03-01

Describing the biomechanical properties of cellular systems, regarded as complex highly viscoelastic materials, is a difficult problem of great conceptual and practical value. Here we present a novel approach, referred to as the Cellular Particle Dynamics (CPD) method, for: (i) quantitatively relating biomechanical properties at the cell level to those at the multicellular and tissue level, and (ii) describing and predicting the time evolution of multicellular systems that undergo biomechanical relaxations. In CPD cells are modeled as an ensemble of cellular particles (CPs) that interact via short range contact interactions, characterized by an attractive (adhesive interaction) and a repulsive (excluded volume interaction) component. The time evolution of the spatial conformation of the multicellular system is determined by following the trajectories of all CPs through integration of their equations of motion. Cell and multicellular level biomechanical properties (e.g., viscosity, surface tension and shear modulus) are determined through the combined use of experiments and theory of continuum viscoelastic media. The same biomechanical properties are also ``measured'' computationally by employing the CPD method, the results being expressed in terms of CPD parameters. Once these parameters have been calibrated experimentally, the formalism provides a systematic framework to predict the time evolution of complex multicellular systems during shape-changing biomechanical transformations. By design, the CPD method is rather flexible and most suitable for multiscale modeling of multicellular system. The spatial level of detail of the system can be easily tuned by changing the number of CPs in a cell. Thus, CPD can be used equally well to describe both cell level processes (e.g., the adhesion of two cells) and tissue level processes (e.g., the formation of 3D constructs of millions of cells through bioprinting). Work supported by NSF [FIBR-0526854 and PHY-0957914

On the origin of biological construction, with a focus on multicellularity.

PubMed

van Gestel, Jordi; Tarnita, Corina E

2017-10-17

Biology is marked by a hierarchical organization: all life consists of cells; in some cases, these cells assemble into groups, such as endosymbionts or multicellular organisms; in turn, multicellular organisms sometimes assemble into yet other groups, such as primate societies or ant colonies. The construction of new organizational layers results from hierarchical evolutionary transitions, in which biological units (e.g., cells) form groups that evolve into new units of biological organization (e.g., multicellular organisms). Despite considerable advances, there is no bottom-up, dynamical account of how, starting from the solitary ancestor, the first groups originate and subsequently evolve the organizing principles that qualify them as new units. Guided by six central questions, we propose an integrative bottom-up approach for studying the dynamics underlying hierarchical evolutionary transitions, which builds on and synthesizes existing knowledge. This approach highlights the crucial role of the ecology and development of the solitary ancestor in the emergence and subsequent evolution of groups, and it stresses the paramount importance of the life cycle: only by evaluating groups in the context of their life cycle can we unravel the evolutionary trajectory of hierarchical transitions. These insights also provide a starting point for understanding the types of subsequent organizational complexity. The central research questions outlined here naturally link existing research programs on biological construction (e.g., on cooperation, multilevel selection, self-organization, and development) and thereby help integrate knowledge stemming from diverse fields of biology.

Biomaterial Substrate-Mediated Multicellular Spheroid Formation and Their Applications in Tissue Engineering.

PubMed

Tseng, Ting-Chen; Wong, Chui-Wei; Hsieh, Fu-Yu; Hsu, Shan-Hui

2017-12-01

Three-dimentional (3D) multicellular aggregates (spheroids), compared to the traditional 2D monolayer cultured cells, are physiologically more similar to the cells in vivo. So far there are various techniques to generate 3D spheroids. Spheroids obtained from different methods have already been applied to regenerative medicine or cancer research. Among the cell spheroids created by different methods, the substrate-derived spheroids and their forming mechanism are unique. This review focuses on the formation of biomaterial substrate-mediated multicellular spheroids and their applications in tissue engineering and tumor models. First, the authors will describe the special chitosan substrate-derived mesenchymal stem cell (MSC) spheroids and their greater regenerative capacities in various tissues. Second, the authors will describe tumor spheroids derived on chitosan and hyaluronan substrates, which serve as a simple in vitro platform to study 3D tumor models or to perform cancer drug screening. Finally, the authors will mention the self-assembly process for substrate-derived multiple cell spheroids (co-spheroids), which may recapitulate the heterotypic cell-cell interaction for co-cultured cells or crosstalk between different types of cells. These unique multicellular mono-spheroids or co-spheroids represent a category of 3D cell culture with advantages of biomimetic cell-cell interaction, better functionalities, and imaging possibilities. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Effect of Substrate Topography on Direct Reprogramming of Fibroblasts to Induced Neurons

PubMed Central

Kulangara, Karina; Adler, Andrew F.; Wang, Hong; Chellappan, Malathi; Hammett, Ellen; Yasuda, Ryohei; Leong, Kam W.

2014-01-01

Cellular reprogramming holds tremendous potential for cell therapy and regenerative medicine. Recently, fibroblasts have been directly converted into induced neurons (iNs) by overexpression of the neuronal transcription factors Ascl1, Brn2 and Myt1L. Hypothesizing that cell-topography interactions could influence the fibroblast-to-neuron reprogramming process, we investigated the effects of various topographies on iNs produced by direct reprogramming. Final iN purity and conversion efficiency were increased on micrograting substrates. Neurite branching was increased on microposts and decreased on microgratings, with a simplified dendritic arbor characterized by the reduction of MAP2+ neurites. Neurite outgrowth increased significantly on various topographies. DNA microarray analysis detected 20 differentially expressed genes in iNs reprogrammed on smooth versus microgratings, and quantitative PCR (qPCR) confirmed the upregulation of Vip and downregulation of Thy1 and Bmp5 on microgratings. Electrophysiology and calcium imaging verified the functionality of these iNs. This study demonstrates the potential of applying topographical cues to optimize cellular reprogramming. PMID:24709523

Origin of Complexity in Multicellular Organisms

NASA Astrophysics Data System (ADS)

Furusawa, Chikara; Kaneko, Kunihiko

2000-06-01

Through extensive studies of dynamical system modeling cellular growth and reproduction, we find evidence that complexity arises in multicellular organisms naturally through evolution. Without any elaborate control mechanism, these systems can exhibit complex pattern formation with spontaneous cell differentiation. Such systems employ a ``cooperative'' use of resources and maintain a larger growth speed than simple cell systems, which exist in a homogeneous state and behave ``selfishly.'' The relevance of the diversity of chemicals and reaction dynamics to the growth of a multicellular organism is demonstrated. Chaotic biochemical dynamics are found to provide the multipotency of stem cells.

Games of multicellularity.

PubMed

Kaveh, Kamran; Veller, Carl; Nowak, Martin A

2016-08-21

Evolutionary game dynamics are often studied in the context of different population structures. Here we propose a new population structure that is inspired by simple multicellular life forms. In our model, cells reproduce but can stay together after reproduction. They reach complexes of a certain size, n, before producing single cells again. The cells within a complex derive payoff from an evolutionary game by interacting with each other. The reproductive rate of cells is proportional to their payoff. We consider all two-strategy games. We study deterministic evolutionary dynamics with mutations, and derive exact conditions for selection to favor one strategy over another. Our main result has the same symmetry as the well-known sigma condition, which has been proven for stochastic game dynamics and weak selection. For a maximum complex size of n=2 our result holds for any intensity of selection. For n≥3 it holds for weak selection. As specific examples we study the prisoner's dilemma and hawk-dove games. Our model advances theoretical work on multicellularity by allowing for frequency-dependent interactions within groups. Copyright © 2016 Elsevier Ltd. All rights reserved.

Treatment of malignant pleural mesothelioma by fibroblast activation protein-specific re-directed T cells

PubMed Central

2013-01-01

Introduction Malignant pleural mesothelioma (MPM) is an incurable malignant disease, which results from chronic exposition to asbestos in at least 70% of the cases. Fibroblast activation protein (FAP) is predominantly expressed on the surface of reactive tumor-associated fibroblasts as well as on particular cancer types. Because of its expression on the cell surface, FAP is an attractive target for adoptive T cell therapy. T cells can be re-directed by retroviral transfer of chimeric antigen receptors (CAR) against tumor-associated antigens (TAA) and therefore represent a therapeutic strategy of adoptive immunotherapy. Methods To evaluate FAP expression immunohistochemistry was performed in tumor tissue from MPM patients. CD8+ human T cells were retrovirally transduced with an anti-FAP-F19-∆CD28/CD3ζ-CAR. T cell function was evaluated in vitro by cytokine release and cytotoxicity assays. In vivo function was tested with an intraperitoneal xenograft tumor model in immunodeficient mice. Results FAP was found to be expressed in all subtypes of MPM. Additionally, FAP expression was evaluated in healthy adult tissue samples and was only detected in specific areas in the pancreas, the placenta and very weakly for cervix and uterus. Expression of the anti-FAP-F19-∆CD28/CD3ζ-CAR in CD8+ T cells resulted in antigen-specific IFNγ release. Additionally, FAP-specific re-directed T cells lysed FAP positive mesothelioma cells and inflammatory fibroblasts in an antigen-specific manner in vitro. Furthermore, FAP-specific re-directed T cells inhibited the growth of FAP positive human tumor cells in the peritoneal cavity of mice and significantly prolonged survival of mice. Conclusion FAP re-directed CD8+ T cells showed antigen-specific functionality in vitro and in vivo. Furthermore, FAP expression was verified in all MPM histotypes. Therefore, our data support performing a phase I clinical trial in which MPM patients are treated with adoptively transferred FAP-specific re-directed

The reverse evolution from multicellularity to unicellularity during carcinogenesis.

PubMed

Chen, Han; Lin, Fangqin; Xing, Ke; He, Xionglei

2015-03-09

Theoretical reasoning suggests that cancer may result from a knockdown of the genetic constraints that evolved for the maintenance of metazoan multicellularity. By characterizing the whole-life history of a xenograft tumour, here we show that metastasis is driven by positive selection for general loss-of-function mutations on multicellularity-related genes. Expression analyses reveal mainly downregulation of multicellularity-related genes and an evolving expression profile towards that of embryonic stem cells, the cell type resembling unicellular life in its capacity of unlimited clonal proliferation. Also, the emergence of metazoan multicellularity ~600 Myr ago is accompanied by an elevated birth rate of cancer genes, and there are more loss-of-function tumour suppressors than activated oncogenes in a typical tumour. These data collectively suggest that cancer represents a loss-of-function-driven reverse evolution back to the unicellular 'ground state'. This cancer evolution model may account for inter-/intratumoural genetic heterogeneity, could explain distant-organ metastases and hold implications for cancer therapy.

Aggregative multicellularity evolved independently in the eukaryotic supergroup Rhizaria.

PubMed

Brown, Matthew W; Kolisko, Martin; Silberman, Jeffrey D; Roger, Andrew J

2012-06-19

Multicellular forms of life have evolved many times, independently giving rise to a diversity of organisms such as animals, plants, and fungi that together comprise the visible biosphere. Yet multicellular life is far more widespread among eukaryotes than just these three lineages. A particularly common form of multicellularity is a social aggregative fruiting lifestyle whereby individual cells associate to form a "fungus-like" sorocarp. This complex developmental process that requires the interaction of thousands of cells working in concert was made famous by the "cellular slime mold"Dictyostelium discoideum, which became an important model organism. Although sorocarpic protistan lineages have been identified in five of the major eukaryote groups, the ubiquitous and globally distributed species Guttulinopsis vulgaris has eluded proper classification. Here we demonstrate, by phylogenomic analyses of a 159-protein data set, that G. vulgaris is a member of Rhizaria and is thus the first member of this eukaryote supergroup known to be capable of aggregative multicellularity. Copyright © 2012 Elsevier Ltd. All rights reserved.

How the evolution of multicellularity set the stage for cancer

PubMed Central

Trigos, Anna S; Pearson, Richard B; Papenfuss, Anthony T; Goode, David L

2018-01-01

Neoplastic growth and many of the hallmark properties of cancer are driven by the disruption of molecular networks established during the emergence of multicellularity. Regulatory pathways and molecules that evolved to impose regulatory constraints upon networks established in earlier unicellular organisms enabled greater communication and coordination between the diverse cell types required for multicellularity, but also created liabilities in the form of points of vulnerability in the network that when mutated or dysregulated facilitate the development of cancer. These factors are usually overlooked in genomic analyses of cancer, but understanding where vulnerabilities to cancer lie in the networks of multicellular species would provide important new insights into how core molecular processes and gene regulation change during tumourigenesis. We describe how the evolutionary origins of genes influence their roles in cancer, and how connections formed between unicellular and multicellular genes that act as key regulatory hubs for normal tissue homeostasis can also contribute to malignant transformation when disrupted. Tumours in general are characterised by increased dependence on unicellular processes for survival, and major dysregulation of the control structures imposed on these processes during the evolution of multicellularity. Mounting molecular evidence suggests altered interactions at the interface between unicellular and multicellular genes play key roles in the initiation and progression of cancer. Furthermore, unicellular network regions activated in cancer show high degrees of robustness and plasticity, conferring increased adaptability to tumour cells by supporting effective responses to environmental pressures such as drug exposure. Examining how the links between multicellular and unicellular regions get disrupted in tumours has great potential to identify novel drivers of cancer, and to guide improvements to cancer treatment by identifying more

Nonmuscle myosin IIA and IIB differentially contribute to intrinsic and directed migration of human embryonic lung fibroblasts.

PubMed

Kuragano, Masahiro; Murakami, Yota; Takahashi, Masayuki

2018-03-25

Nonmuscle myosin II (NMII) plays an essential role in directional cell migration. In this study, we investigated the roles of NMII isoforms (NMIIA and NMIIB) in the migration of human embryonic lung fibroblasts, which exhibit directionally persistent migration in an intrinsic manner. NMIIA-knockdown (KD) cells migrated unsteadily, but their direction of migration was approximately maintained. By contrast, NMIIB-KD cells occasionally reversed their direction of migration. Lamellipodium-like protrusions formed in the posterior region of NMIIB-KD cells prior to reversal of the migration direction. Moreover, NMIIB KD led to elongation of the posterior region in migrating cells, probably due to the lack of load-bearing stress fibers in this area. These results suggest that NMIIA plays a role in steering migration by maintaining stable protrusions in the anterior region, whereas NMIIB plays a role in maintenance of front-rear polarity by preventing aberrant protrusion formation in the posterior region. These distinct functions of NMIIA and NMIIB might promote intrinsic and directed migration of normal human fibroblasts. Copyright © 2018 Elsevier Inc. All rights reserved.

Optimization of Direct Fibroblast Reprogramming to Cardiomyocytes Using Calcium Activity as a Functional Measure of Success

PubMed Central

Addis, Russell C.; Ifkovits, Jamie L.; Pinto, Filipa; Kellam, Lori D.; Esteso, Paul; Rentschler, Stacey; Christoforou, Nicolas; Epstein, Jonathan A.; Gearhart, John D.

2013-01-01

Direct conversion of fibroblasts to induced cardiomyocytes (iCMs) has great potential for regenerative medicine. Recent publications have reported significant progress, but the evaluation of reprogramming has relied upon non-functional measures such as flow cytometry for cardiomyocyte markers or GFP expression driven by a cardiomyocyte-specific promoter. The issue is one of practicality: the most stringent measures - electrophysiology to detect cell excitation and the presence of spontaneously contracting myocytes - are not readily quantifiable in the large numbers of cells screened in reprogramming experiments. However, excitation and contraction are linked by a third functional characteristic of cardiomyocytes: the rhythmic oscillation of intracellular calcium levels. We set out to optimize direct conversion of fibroblasts to iCMs with a quantifiable calcium reporter to rapidly assess functional transdifferentiation. We constructed a reporter system in which the calcium indicator GCaMP is driven by the cardiomyocyte-specific Troponin T promoter. Using calcium activity as our primary outcome measure, we compared several published combinations of transcription factors along with novel combinations in mouse embryonic fibroblasts. The most effective combination consisted of Hand2, Nkx2.5, Gata4, Mef2c, and Tbx5 (HNGMT). This combination is >50-fold more efficient than GMT alone and produces iCMs with cardiomyocyte marker expression, robust calcium oscillation, and spontaneous beating that persists for weeks following inactivation of reprogramming factors. HNGMT is also significantly more effective than previously published factor combinations for the transdifferentiation of adult mouse cardiac fibroblasts to iCMs. Quantification of calcium function is a convenient and effective means for the identification and evaluation of cardiomyocytes generated by direct reprogramming. Using this stringent outcome measure, we conclude that HNGMT produces iCMs more efficiently

Optimization of direct fibroblast reprogramming to cardiomyocytes using calcium activity as a functional measure of success.

PubMed

Addis, Russell C; Ifkovits, Jamie L; Pinto, Filipa; Kellam, Lori D; Esteso, Paul; Rentschler, Stacey; Christoforou, Nicolas; Epstein, Jonathan A; Gearhart, John D

2013-07-01

Direct conversion of fibroblasts to induced cardiomyocytes (iCMs) has great potential for regenerative medicine. Recent publications have reported significant progress, but the evaluation of reprogramming has relied upon non-functional measures such as flow cytometry for cardiomyocyte markers or GFP expression driven by a cardiomyocyte-specific promoter. The issue is one of practicality: the most stringent measures - electrophysiology to detect cell excitation and the presence of spontaneously contracting myocytes - are not readily quantifiable in the large numbers of cells screened in reprogramming experiments. However, excitation and contraction are linked by a third functional characteristic of cardiomyocytes: the rhythmic oscillation of intracellular calcium levels. We set out to optimize direct conversion of fibroblasts to iCMs with a quantifiable calcium reporter to rapidly assess functional transdifferentiation. We constructed a reporter system in which the calcium indicator GCaMP is driven by the cardiomyocyte-specific Troponin T promoter. Using calcium activity as our primary outcome measure, we compared several published combinations of transcription factors along with novel combinations in mouse embryonic fibroblasts. The most effective combination consisted of Hand2, Nkx2.5, Gata4, Mef2c, and Tbx5 (HNGMT). This combination is >50-fold more efficient than GMT alone and produces iCMs with cardiomyocyte marker expression, robust calcium oscillation, and spontaneous beating that persist for weeks following inactivation of reprogramming factors. HNGMT is also significantly more effective than previously published factor combinations for the transdifferentiation of adult mouse cardiac fibroblasts to iCMs. Quantification of calcium function is a convenient and effective means for the identification and evaluation of cardiomyocytes generated by direct reprogramming. Using this stringent outcome measure, we conclude that HNGMT produces iCMs more efficiently than

Evolution of cytokinesis-related protein localization during the emergence of multicellularity in volvocine green algae.

PubMed

Arakaki, Yoko; Fujiwara, Takayuki; Kawai-Toyooka, Hiroko; Kawafune, Kaoru; Featherston, Jonathan; Durand, Pierre M; Miyagishima, Shin-Ya; Nozaki, Hisayoshi

2017-12-06

The volvocine lineage, containing unicellular Chlamydomonas reinhardtii and differentiated multicellular Volvox carteri, is a powerful model for comparative studies aiming at understanding emergence of multicellularity. Tetrabaena socialis is the simplest multicellular volvocine alga and belongs to the family Tetrabaenaceae that is sister to more complex multicellular volvocine families, Goniaceae and Volvocaceae. Thus, T. socialis is a key species to elucidate the initial steps in the evolution of multicellularity. In the asexual life cycle of C. reinhardtii and multicellular volvocine species, reproductive cells form daughter cells/colonies by multiple fission. In embryogenesis of the multicellular species, daughter protoplasts are connected to one another by cytoplasmic bridges formed by incomplete cytokinesis during multiple fission. These bridges are important for arranging the daughter protoplasts in appropriate positions such that species-specific integrated multicellular individuals are shaped. Detailed comparative studies of cytokinesis between unicellular and simple multicellular volvocine species will help to elucidate the emergence of multicellularity from the unicellular ancestor. However, the cytokinesis-related genes between closely related unicellular and multicellular species have not been subjected to a comparative analysis. Here we focused on dynamin-related protein 1 (DRP1), which is known for its role in cytokinesis in land plants. Immunofluorescence microscopy using an antibody against T. socialis DRP1 revealed that volvocine DRP1 was localized to division planes during cytokinesis in unicellular C. reinhardtii and two simple multicellular volvocine species T. socialis and Gonium pectorale. DRP1 signals were mainly observed in the newly formed division planes of unicellular C. reinhardtii during multiple fission, whereas in multicellular T. socialis and G. pectorale, DRP1 signals were observed in all division planes during embryogenesis. These

Self-Directed Workplace Learning.

ERIC Educational Resources Information Center

1998

This document contains four papers from a symposium on self-directed workplace learning. "Self-Directed Work Teams: Implementation and Performance" (Marcel van der Klink, Hilde ter Horst) discusses the results of a study examining the implementation and effects of self-directed work teams in a land register office and the role of the…

Emergence of multicellular organisms with dynamic differentiation and spatial pattern.

PubMed

Furusawa, C; Kaneko, K

1998-01-01

The origin of multicellular organisms and the mechanism of development in cell societies are studied by choosing a model with intracellular biochemical dynamics allowing for oscillations, cell-cell interaction through diffusive chemicals on a two-dimensional grid, and state-dependent cell adhesion. Cells differentiate due to a dynamical instability, as described by our "isologous diversification" theory. A fixed spatial pattern of differentiated cells emerges, where spatial information is sustained by cell-cell interactions. This pattern is robust against perturbations. With an adequate cell adhesion force, active cells are release that form the seed of a new generation of multicellular organisms, accompanied by death of the original multicellular unit as a halting state. It is shown that the emergence of multicellular organisms with differentiation, regulation, and life cycle is not an accidental event, but a natural consequence in a system of replicating cells with growth.

Transcriptional response of dermal fibroblasts in direct current electric fields.

PubMed

Jennings, Jessica; Chen, Dongquan; Feldman, Dale

2008-07-01

During the course of normal wound healing, fibroblasts at the wound edge are exposed to electric fields (EFs) ranging from 40 to 200 mV/mm. Various forms of EFs influence fibroblast migration, proliferation, and protein synthesis. Thus, EFs may contribute to fibroblast activation during wound repair. To elucidate the role of EFs during the normal progression of healing, this study compares gene expression in normal adult dermal fibroblasts exposed to a 100 mV/mm EF for 1 h to non-stimulated controls. Significantly increased expression of 162 transcripts and decreased expression of 302 transcripts was detected using microarrays, with 126 transcripts above the level of 1.4-fold increases or decreases compared to the controls. Above the level of twofold, only 11 genes were significantly increased or decreased compared to controls. Many of these significantly regulated genes are associated with wound repair through the processes of matrix production, cellular signaling, and growth. Activity within specific cellular signaling pathways is noted, including TGF-beta, G-proteins, and inhibition of apoptosis. In addition, RT-PCR analysis of the expression of KLF6, FN1, RGS2, and JMJD1C over continued stimulation and at different field strengths suggests that there are specific windows of field characteristics for maximum induction of these genes. EFs thus appear to have an important role in controlling fibroblast activity in the process of wound healing.

Direct Reprogramming of Murine Fibroblasts to Hematopoietic Progenitor Cells

PubMed Central

Batta, Kiran; Florkowska, Magdalena; Kouskoff, Valerie; Lacaud, Georges

2014-01-01

Summary Recent reports have shown that somatic cells, under appropriate culture conditions, could be directly reprogrammed to cardiac, hepatic, or neuronal phenotype by lineage-specific transcription factors. In this study, we demonstrate that both embryonic and adult somatic fibroblasts can be efficiently reprogrammed to clonal multilineage hematopoietic progenitors by the ectopic expression of the transcription factors ERG, GATA2, LMO2, RUNX1c, and SCL. These reprogrammed cells were stably expanded on stromal cells and possessed short-term reconstitution ability in vivo. Loss of p53 function facilitated reprogramming to blood, and p53−/− reprogrammed cells efficiently generated erythroid, megakaryocytic, myeloid, and lymphoid lineages. Genome-wide analyses revealed that generation of hematopoietic progenitors was preceded by the appearance of hemogenic endothelial cells expressing endothelial and hematopoietic genes. Altogether, our findings suggest that direct reprogramming could represent a valid alternative approach to the differentiation of embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) for disease modeling and autologous blood cell therapies. PMID:25466247

Experimental evolution of an alternating uni- and multicellular life cycle in Chlamydomonas reinhardtii

PubMed Central

Ratcliff, William C.; Herron, Matthew D.; Howell, Kathryn; Pentz, Jennifer T.; Rosenzweig, Frank; Travisano, Michael

2013-01-01

The transition to multicellularity enabled the evolution of large, complex organisms, but early steps in this transition remain poorly understood. Here we show that multicellular complexity, including development from a single cell, can evolve rapidly in a unicellular organism that has never had a multicellular ancestor. We subject the alga Chlamydomonas reinhardtii to conditions that favour multicellularity, resulting in the evolution of a multicellular life cycle in which clusters reproduce via motile unicellular propagules. While a single-cell genetic bottleneck during ontogeny is widely regarded as an adaptation to limit among-cell conflict, its appearance very early in this transition suggests that it did not evolve for this purpose. Instead, we find that unicellular propagules are adaptive even in the absence of intercellular conflict, maximizing cluster-level fecundity. These results demonstrate that the unicellular bottleneck, a trait essential for evolving multicellular complexity, can arise rapidly via co-option of the ancestral unicellular form. PMID:24193369

Cooperatively Generated Stresslet Flows Supply Fresh Fluid to Multicellular Choanoflagellate Colonies

NASA Astrophysics Data System (ADS)

Roper, Marcus; Dayel, Mark J.; Pepper, Rachel E.; Koehl, M. A. R.

2013-05-01

The flagellated protozoan Salpingoeca rosetta is one of the closest relatives of multicellular animals. Unicellular S. rosetta can be induced to form multicellular colonies, but colonies swim more slowly than individual cells so the advantages conferred by colony formation are uncertain. Here we use theoretical models to show that hydrodynamic cooperation between cells can increase the fluid supply to the colony, an important predictor of feeding rate. Our results suggest that hydrodynamic benefits may have been an important selective factor in the evolution of early multicellular animals.

Matrix-directed differentiation of human adipose-derived mesenchymal stem cells to dermal-like fibroblasts that produce extracellular matrix.

PubMed

Sivan, Unnikrishnan; Jayakumar, K; Krishnan, Lissy K

2016-10-01

Commercially available skin substitutes lack essential non-immune cells for adequate tissue regeneration of non-healing wounds. A tissue-engineered, patient-specific, dermal substitute could be an attractive option for regenerating chronic wounds, for which adipose-derived mesenchymal stem cells (ADMSCs) could become an autologous source. However, ADMSCs are multipotent in nature and may differentiate into adipocytes, osteocytes and chondrocytes in vitro, and may develop into undesirable tissues upon transplantation. Therefore, ADMSCs committed to the fibroblast lineage could be a better option for in vitro or in vivo skin tissue engineering. The objective of this study was to standardize in vitro culture conditions for ADMSCs differentiation into dermal-like fibroblasts which can synthesize extracellular matrix (ECM) proteins. Biomimetic matrix composite, deposited on tissue culture polystyrene (TCPS), and differentiation medium (DM), supplemented with fibroblast-conditioned medium and growth factors, were used as a fibroblast-specific niche (FSN) for cell culture. For controls, ADMSCs were cultured on bare TCPS with either DM or basal medium (BM). Culture of ADMSCs on FSN upregulated the expression of differentiation markers such as fibroblast-specific protein-1 (FSP-1) and a panel of ECM molecules specific to the dermis, such as fibrillin-1, collagen I, collagen IV and elastin. Immunostaining showed the deposition of dermal-specific ECM, which was significantly higher in FSN compared to control. Fibroblasts derived from ADMSCs can synthesize elastin, which is an added advantage for successful skin tissue engineering as compared to fibroblasts from skin biopsy. To obtain rapid differentiation of ADMSCs to dermal-like fibroblasts for regenerative medicine, a matrix-directed differentiation strategy may be employed. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

Experimental evolution of multicellularity using microbial pseudo-organisms.

PubMed

Queller, David C; Strassmann, Joan E

2013-02-23

In a major evolutionary transition to a new level of organization, internal conflicts must be controlled before the transition can truly be successful. One such transition is that from single cells to multicellularity. Conflicts among cells in multicellular organisms can be greatly reduced if they consist of genetically identical clones. However, mutations to cheaters that experience one round of within-individual selection could still be a problem, particularly for certain life cycles. We propose an experimental evolution method to investigate this issue, using micro-organisms to construct multicellular pseudo-organisms, which can be evolved under different artificial life cycles. These experiments can be used to test the importance of various life cycle features in maintaining cooperation. They include structured reproduction, in which small propagule size reduces within-individual genetic variation. They also include structured growth, which increases local relatedness within individual bodies. Our method provides a novel way to test how different life cycles favour cooperation, even for life cycles that do not exist.

Differential activation of human T cells to allogeneic endothelial cells, epithelial cells and fibroblasts in vitro

PubMed Central

2012-01-01

Background In the direct pathway, T cells recognize intact donor major histocompatability complexes and allogeneic peptide on the surface of donor antigen presenting cells (APCs). Indirect allorecognition results from the recognition of processed alloantigen by self MHC complexes on self APCs. In this study, we wished to evaluate the relative contribution of different intragraft cells to the alloactivation of nave and memory T cells though the direct and the indirect pathway of allorecognition. Methods The processing of membrane fragments from IFN-treated single donor endothelial cells (EC), fibroblasts or renal epithelial cells (RPTEC) was evaluated by DiOC labeling of each cell type and flow cytometry following interaction with PBMC. Direct pathway activation of nave CD45RA+ or memory CD45RO+ CD4+ T cells was evaluated following coculture with IFN-treated and MHC class II-expressing EC, fibroblasts or RPTEC. Indirect pathway activation was assessed using CD45RA+ or CD45RO+ CD4+ T cells cocultured with autologous irradiated APCs in the absence or presence of sonicates derived from IFN-treated allogeneic EC, fibroblasts or RPTEC. Activation of T cells was assessed by [3H]thymidine incorporation and by ELISpot assays. Results We find that CD14+ APCs readily acquire membrane fragments from fibroblasts and RPTEC, but fail to acquire membrane fragments from intact EC. However, APCs process membranes from EC undergoing apoptosis.There was a notable direct pathway alloproliferative response of CD45RO+ CD4+ T cells to IFN-treated EC, but not to fibroblasts or RPTEC. Also, there was a minimal direct pathway response of CD45RA+ CD4+ T cells to all cell types. In contrast, we found that both CD45RA+ and CD45RO+ CD4+ T cells proliferated following coculture with autologous APCs in the presence of sonicates derived from IFN-treated EC, fibroblasts or RPTEC. By ELISpot, we found that these T cells stimulated via the indirect pathway also produced the cytokines IFN, IL-2, IL-4

Multicellular microorganisms: laboratory versus nature.

PubMed

Palková, Zdena

2004-05-01

Our present in-depth knowledge of the physiology and regulatory mechanisms of microorganisms has arisen from our ability to remove them from their natural, complex ecosystems into pure liquid cultures. These cultures are grown under optimized laboratory conditions and allow us to study microorganisms as individuals. However, microorganisms naturally grow in conditions that are far from optimal, which causes them to become organized into multicellular communities that are better protected against the harmful environment. Moreover, this multicellular existence allows individual cells to differentiate and acquire specific properties, such as forming resistant spores, which benefit the whole population. The relocation of natural microorganisms to the laboratory can result in their adaptation to these favourable conditions, which is accompanied by complex changes that include the repression of some protective mechanisms that are essential in nature. Laboratory microorganisms that have been cultured for long periods under optimized conditions might therefore differ markedly from those that exist in natural ecosystems.

Expanding Horizons in Self-Directed Learning.

ERIC Educational Resources Information Center

Long, Huey B.; And Others

The following papers are included: "Preface" (Huey B. Long); "Self-Directed Learning: Smoke and Mirrors?" (Huey B. Long); "From Self-Culture to Self-Direction: An Historical Analysis of Self-Directed Learning" (Amy D. Rose); "The Link between Self-Directed and Transformative Learning" (Jane Pilling-Cormick);…

Myxobacteria, Polarity, and Multicellular Morphogenesis

PubMed Central

Kaiser, Dale; Robinson, Mark; Kroos, Lee

2010-01-01

Myxobacteria are renowned for the ability to sporulate within fruiting bodies whose shapes are species-specific. The capacity to build those multicellular structures arises from the ability of M. xanthus to organize high cell-density swarms, in which the cells tend to be aligned with each other while constantly in motion. The intrinsic polarity of rod-shaped cells lays the foundation, and each cell uses two polar engines for gliding on surfaces. It sprouts retractile type IV pili from the leading cell pole and secretes capsular polysaccharide through nozzles from the trailing pole. Regularly periodic reversal of the gliding direction was found to be required for swarming. Those reversals are generated by a G-protein switch which is driven by a sharply tuned oscillator. Starvation induces fruiting body development, and systematic reductions in the reversal frequency are necessary for the cells to aggregate rather than continue to swarm. Developmental gene expression is regulated by a network that is connected to the suppression of reversals. PMID:20610548

Regulated aggregative multicellularity in a close unicellular relative of metazoa

PubMed Central

Sebé-Pedrós, Arnau; Irimia, Manuel; del Campo, Javier; Parra-Acero, Helena; Russ, Carsten; Nusbaum, Chad; Blencowe, Benjamin J; Ruiz-Trillo, Iñaki

2013-01-01

The evolution of metazoans from their unicellular ancestors was one of the most important events in the history of life. However, the cellular and genetic changes that ultimately led to the evolution of multicellularity are not known. In this study, we describe an aggregative multicellular stage in the protist Capsaspora owczarzaki, a close unicellular relative of metazoans. Remarkably, transition to the aggregative stage is associated with significant upregulation of orthologs of genes known to establish multicellularity and tissue architecture in metazoans. We further observe transitions in regulated alternative splicing during the C. owczarzaki life cycle, including the deployment of an exon network associated with signaling, a feature of splicing regulation so far only observed in metazoans. Our results reveal the existence of a highly regulated aggregative stage in C. owczarzaki and further suggest that features of aggregative behavior in an ancestral protist may had been co-opted to develop some multicellular properties currently seen in metazoans. DOI: http://dx.doi.org/10.7554/eLife.01287.001 PMID:24368732

Division of labour and the evolution of multicellularity

PubMed Central

Ispolatov, Iaroslav; Ackermann, Martin; Doebeli, Michael

2012-01-01

Understanding the emergence and evolution of multicellularity and cellular differentiation is a core problem in biology. We develop a quantitative model that shows that a multicellular form emerges from genetically identical unicellular ancestors when the compartmentalization of poorly compatible physiological processes into component cells of an aggregate produces a fitness advantage. This division of labour between the cells in the aggregate occurs spontaneously at the regulatory level owing to mechanisms present in unicellular ancestors and does not require any genetic predisposition for a particular role in the aggregate or any orchestrated cooperative behaviour of aggregate cells. Mathematically, aggregation implies an increase in the dimensionality of phenotype space that generates a fitness landscape with new fitness maxima, in which the unicellular states of optimized metabolism become fitness saddle points. Evolution of multicellularity is modelled as evolution of a hereditary parameter: the propensity of cells to stick together, which determines the fraction of time a cell spends in the aggregate form. Stickiness can increase evolutionarily owing to the fitness advantage generated by the division of labour between cells in an aggregate. PMID:22158952

Cellular packing, mechanical stress and the evolution of multicellularity

NASA Astrophysics Data System (ADS)

Jacobeen, Shane; Pentz, Jennifer T.; Graba, Elyes C.; Brandys, Colin G.; Ratcliff, William C.; Yunker, Peter J.

2018-03-01

The evolution of multicellularity set the stage for sustained increases in organismal complexity1-5. However, a fundamental aspect of this transition remains largely unknown: how do simple clusters of cells evolve increased size when confronted by forces capable of breaking intracellular bonds? Here we show that multicellular snowflake yeast clusters6-8 fracture due to crowding-induced mechanical stress. Over seven weeks ( 291 generations) of daily selection for large size, snowflake clusters evolve to increase their radius 1.7-fold by reducing the accumulation of internal stress. During this period, cells within the clusters evolve to be more elongated, concomitant with a decrease in the cellular volume fraction of the clusters. The associated increase in free space reduces the internal stress caused by cellular growth, thus delaying fracture and increasing cluster size. This work demonstrates how readily natural selection finds simple, physical solutions to spatial constraints that limit the evolution of group size—a fundamental step in the evolution of multicellularity.

Evolution of multicellularity coincided with increased diversification of cyanobacteria and the Great Oxidation Event.

PubMed

Schirrmeister, Bettina E; de Vos, Jurriaan M; Antonelli, Alexandre; Bagheri, Homayoun C

2013-01-29

Cyanobacteria are among the most diverse prokaryotic phyla, with morphotypes ranging from unicellular to multicellular filamentous forms, including those able to terminally (i.e., irreversibly) differentiate in form and function. It has been suggested that cyanobacteria raised oxygen levels in the atmosphere around 2.45-2.32 billion y ago during the Great Oxidation Event (GOE), hence dramatically changing life on the planet. However, little is known about the temporal evolution of cyanobacterial lineages, and possible interplay between the origin of multicellularity, diversification of cyanobacteria, and the rise of atmospheric oxygen. We estimated divergence times of extant cyanobacterial lineages under Bayesian relaxed clocks for a dataset of 16S rRNA sequences representing the entire known diversity of this phylum. We tested whether the evolution of multicellularity overlaps with the GOE, and whether multicellularity is associated with significant shifts in diversification rates in cyanobacteria. Our results indicate an origin of cyanobacteria before the rise of atmospheric oxygen. The evolution of multicellular forms coincides with the onset of the GOE and an increase in diversification rates. These results suggest that multicellularity could have played a key role in triggering cyanobacterial evolution around the GOE.

Evolution of multicellularity coincided with increased diversification of cyanobacteria and the Great Oxidation Event

PubMed Central

Schirrmeister, Bettina E.; de Vos, Jurriaan M.; Antonelli, Alexandre; Bagheri, Homayoun C.

2013-01-01

Cyanobacteria are among the most diverse prokaryotic phyla, with morphotypes ranging from unicellular to multicellular filamentous forms, including those able to terminally (i.e., irreversibly) differentiate in form and function. It has been suggested that cyanobacteria raised oxygen levels in the atmosphere around 2.45–2.32 billion y ago during the Great Oxidation Event (GOE), hence dramatically changing life on the planet. However, little is known about the temporal evolution of cyanobacterial lineages, and possible interplay between the origin of multicellularity, diversification of cyanobacteria, and the rise of atmospheric oxygen. We estimated divergence times of extant cyanobacterial lineages under Bayesian relaxed clocks for a dataset of 16S rRNA sequences representing the entire known diversity of this phylum. We tested whether the evolution of multicellularity overlaps with the GOE, and whether multicellularity is associated with significant shifts in diversification rates in cyanobacteria. Our results indicate an origin of cyanobacteria before the rise of atmospheric oxygen. The evolution of multicellular forms coincides with the onset of the GOE and an increase in diversification rates. These results suggest that multicellularity could have played a key role in triggering cyanobacterial evolution around the GOE. PMID:23319632

In vitro spatially organizing the differentiation in individual multicellular stem cell aggregates.

PubMed

Qi, Hao; Huang, Guoyou; Han, Yu Long; Lin, Wang; Li, Xiujun; Wang, Shuqi; Lu, Tian Jian; Xu, Feng

2016-01-01

With significant potential as a robust source to produce specific somatic cells for regenerative medicine, stem cells have attracted increasing attention from both academia and government. In vivo, stem cell differentiation is a process under complicated regulations to precisely build tissue with unique spatial structures. Since multicellular spheroidal aggregates of stem cells, commonly called as embryoid bodies (EBs), are considered to be capable of recapitulating the events in early stage of embryonic development, a variety of methods have been developed to form EBs in vitro for studying differentiation of embryonic stem cells. The regulation of stem cell differentiation is crucial in directing stem cells to build tissue with the correct spatial architecture for specific functions. However, stem cells within the three-dimensional multicellular aggregates undergo differentiation in a less unpredictable and spatially controlled manner in vitro than in vivo. Recently, various microengineering technologies have been developed to manipulate stem cells in vitro in a spatially controlled manner. Herein, we take the spotlight on these technologies and researches that bring us the new potential for manipulation of stem cells for specific purposes.

A phase field approach for multicellular aggregate fusion in biofabrication.

PubMed

Yang, Xiaofeng; Sun, Yi; Wang, Qi

2013-07-01

We present a modeling and computational approach to study fusion of multicellular aggregates during tissue and organ fabrication, which forms the foundation for the scaffold-less biofabrication of tissues and organs known as bioprinting. It is known as the phase field method, where multicellular aggregates are modeled as mixtures of multiphase complex fluids whose phase mixing or separation is governed by interphase force interactions, mimicking the cell-cell interaction in the multicellular aggregates, and intermediate range interaction mediated by the surrounding hydrogel. The material transport in the mixture is dictated by hydrodynamics as well as forces due to the interphase interactions. In a multicellular aggregate system with fixed number of cells and fixed amount of the hydrogel medium, the effect of cell differentiation, proliferation, and death are neglected in the current model, which can be readily included in the model, and the interaction between different components is dictated by the interaction energy between cell and cell as well as between cell and medium particles, respectively. The modeling approach is applicable to transient simulations of fusion of cellular aggregate systems at the time and length scale appropriate to biofabrication. Numerical experiments are presented to demonstrate fusion and cell sorting during tissue and organ maturation processes in biofabrication.

The Evolution of Multicellular Plants and Animals.

ERIC Educational Resources Information Center

Valentine, James W.

1978-01-01

Traces the evolution of unicellular organisms to the multi-cellular plants and animals in existence today. Major events are depicted in a geologic timetable. Organisms, extinct and recent, are classified by taxonomic group. (MA)

Molecular Regulation of the Mitosis/Meiosis Decision in Multicellular Organisms

PubMed Central

Kimble, Judith

2011-01-01

A major step in the journey from germline stem cell to differentiated gamete is the decision to leave the mitotic cell cycle and begin progression through the meiotic cell cycle. Over the past decade, molecular regulators of the mitosis/meiosis decision have been discovered in most of the major model multicellular organisms. Historically, the mitosis/meiosis decision has been closely linked with controls of germline self-renewal and the sperm/egg decision, especially in nematodes and mice. Molecular explanations of those linkages clarify our understanding of this fundamental germ cell decision, and unifying themes have begun to emerge. Although the complete circuitry of the decision is not known in any organism, the recent advances promise to impact key issues in human reproduction and agriculture. PMID:21646377

Molecular regulation of the mitosis/meiosis decision in multicellular organisms.

PubMed

Kimble, Judith

2011-08-01

A major step in the journey from germline stem cell to differentiated gamete is the decision to leave the mitotic cell cycle and begin progression through the meiotic cell cycle. Over the past decade, molecular regulators of the mitosis/meiosis decision have been discovered in most of the major model multicellular organisms. Historically, the mitosis/meiosis decision has been closely linked with controls of germline self-renewal and the sperm/egg decision, especially in nematodes and mice. Molecular explanations of those linkages clarify our understanding of this fundamental germ cell decision, and unifying themes have begun to emerge. Although the complete circuitry of the decision is not known in any organism, the recent advances promise to impact key issues in human reproduction and agriculture.

Cytotoxicity of Etch-and-Rinse, Self-Etch, and Universal Dental Adhesive Systems in Fibroblast Cell Line 3T3

PubMed Central

Bernardo, Cintia Fernanda de Freitas; de Souza, Francielly Fernanda de Freitas A.; Michél, Milton Domingos; Ribeiro, Camila Nunes de Morais; Germano, Sandro; Maluf, Daniela Florencio

2017-01-01

The aim of this study was to evaluate in fibroblast cultures the direct cytotoxic effects of etch-and-rinse, self-etch, and universal adhesive systems. The sterile glass cover slips (n = 3) were then immersed in culture medium to obtain the eluates for the experimental groups: (1) Adper™ Single Bond 2; (2) Ambar; (3) Adper™ Scotchbond™ Multi-Purpose; (4) Scotchbond™ Universal; (5) Ambar Universal; and (6) OptiBond All-In-One. As a negative control, sterile glass cover slips were immersed in culture medium only. After 24 h, the eluate obtained was applied on fibroblast culture. Cell viability and cell morphology were evaluated by MTT assay and SEM, respectively. Data were analyzed by Kruskal–Wallis and Mann–Whitney tests (α = 0.05). All adhesive systems except universal reduced cell viability in 3T3 cells to between 26.04% and 56.57%, and Scotchbond Universal and Ambar Universal reduced cell viability to 2.13% and 3.57%, respectively, when compared to the negative control. Cytoplasmic membrane shrinkage and cell-free areas with residual membrane fragments from dead cells were observed. In conclusion, improvements in universal adhesive system formulations and their mechanisms of action are not accompanied by increased toxicity compared with those in other systems, warranting commitment to the use of these dentin-pulp complexes. PMID:29109829

Constraint Based Modeling Going Multicellular.

PubMed

Martins Conde, Patricia do Rosario; Sauter, Thomas; Pfau, Thomas

2016-01-01

Constraint based modeling has seen applications in many microorganisms. For example, there are now established methods to determine potential genetic modifications and external interventions to increase the efficiency of microbial strains in chemical production pipelines. In addition, multiple models of multicellular organisms have been created including plants and humans. While initially the focus here was on modeling individual cell types of the multicellular organism, this focus recently started to switch. Models of microbial communities, as well as multi-tissue models of higher organisms have been constructed. These models thereby can include different parts of a plant, like root, stem, or different tissue types in the same organ. Such models can elucidate details of the interplay between symbiotic organisms, as well as the concerted efforts of multiple tissues and can be applied to analyse the effects of drugs or mutations on a more systemic level. In this review we give an overview of the recent development of multi-tissue models using constraint based techniques and the methods employed when investigating these models. We further highlight advances in combining constraint based models with dynamic and regulatory information and give an overview of these types of hybrid or multi-level approaches.

Self-Directed Learning: Application and Research.

ERIC Educational Resources Information Center

Long, Huey B.; And Others

These 23 papers provide as complete a picture as possible of the current efforts in self-directed learning application and research. The papers are: "Learning about Self-Directed Learning" (Long); "Philosophical, Psychological, and Practical Justifications for Studying Self-Direction in Learning" (Long); "In Search of…

Differences in species richness patterns between unicellular and multicellular organisms.

PubMed

Hillebrand, Helmut; Watermann, Frank; Karez, Rolf; Berninger, Ulrike-G

2001-01-01

For unicellular organisms, a lack of effects of local species richness on ecosystem function has been proposed due to their locally high species richness and their ubiquitous distribution. High dispersal ability and high individual numbers may enable unicellular taxa to occur everywhere. Using our own and published data sets on uni- and multicellular organisms, we conducted thorough statistical analyses to test whether (1) unicellular taxa show higher relative local species richness compared to multicellular taxa, (2) unicellular taxa show lower slopes of the species:area relationships and species:individuals relationships, and (3) the species composition of unicellular taxa is less influenced by geographic distance compared to multicellular taxa. We found higher local species richness compared to the global species pool for unicellular organisms than for metazoan taxa. The difference was significant if global species richness was conservatively estimated but not if extrapolated, and therefore higher richness estimates were used. Both microalgae and protozoans showed lower slopes between species richness and sample size (area or individuals) compared to macrozoobenthos, also indicating higher local species richness for unicellular taxa. The similarity of species composition of both benthic diatoms and ciliates decreased with increasing geographic distance. This indicated restricted dispersal ability of protists and the absence of ubiquity. However, a steeper slope between similarity and distance was found for polychaetes and corals, suggesting a stronger effect of distance on the dispersal of metazoans compared to unicellular taxa. In conclusion, we found partly different species richness patterns among uni- and multicellular eukaryotes, but no strict ubiquity of unicellular taxa. Therefore, the effect of local unicellular species richness on ecosystem function has to be reanalyzed. Macroecological patterns suggested for multicellular organisms may differ in

Droplet-based microfluidic system for multicellular tumor spheroid formation and anticancer drug testing.

PubMed

Yu, Linfen; Chen, Michael C W; Cheung, Karen C

2010-09-21

Creating multicellular tumor spheroids is critical for characterizing anticancer treatments since it may provide a better model than monolayer culture of tumor cells. Moreover, continuous dynamic perfusion allows the establishment of long term cell culture and subsequent multicellular spheroid formation. A droplet-based microfluidic system was used to form alginate beads with entrapped breast tumor cells. After gelation, the alginate beads were trapped in microsieve structures for cell culture in a continuous perfusion system. The alginate environment permitted cell proliferation and the formation of multicellular spheroids was observed. The dose-dependent response of the tumor spheroids to doxorubicin, and anticancer drug, showed multicellular resistance compared to conventional monolayer culture. The microsieve structures maintain constant location of each bead in the same position throughout the device seeding process, cell proliferation and spheroid formation, treatment with drug, and imaging, permitting temporal and spatial tracking.

Cardiac Niche Influences the Direct Reprogramming of Canine Fibroblasts into Cardiomyocyte-Like Cells

PubMed Central

Palazzolo, Giacomo; Quattrocelli, Mattia; Toelen, Jaan; Dominici, Roberto; Tettamenti, Guido; Barthelemy, Inès; Blot, Stephane; Gijsbers, Rik; Cassano, Marco

2016-01-01

The Duchenne and Becker muscular dystrophies are caused by mutation of dystrophin gene and primarily affect skeletal and cardiac muscles. Cardiac involvement in dystrophic GRMD dogs has been demonstrated by electrocardiographic studies with the onset of a progressive cardiomyopathy similar to the cardiac disease in DMD patients. In this respect, GRMD is a useful model to explore cardiac and skeletal muscle pathogenesis and for developing new therapeutic protocols. Here we describe a protocol to convert GRMD canine fibroblasts isolated from heart and skin into induced cardiac-like myocytes (ciCLMs). We used a mix of transcription factors (GATA4, HAND2, TBX5, and MEF2C), known to be able to differentiate mouse and human somatic cells into ciCLMs. Exogenous gene expression was obtained using four lentiviral vectors carrying transcription factor genes and different resistance genes. Our data demonstrate a direct switch from fibroblast into ciCLMs with no activation of early cardiac genes. ciCLMs were unable to contract spontaneously, suggesting, differently from mouse and human cells, an incomplete differentiation process. However, when transplanted in neonatal hearts of SCID/Beige mice, ciCLMs participate in cardiac myogenesis. PMID:26681949

Cardiac Niche Influences the Direct Reprogramming of Canine Fibroblasts into Cardiomyocyte-Like Cells.

PubMed

Palazzolo, Giacomo; Quattrocelli, Mattia; Toelen, Jaan; Dominici, Roberto; Anastasia, Luigi; Tettamenti, Guido; Barthelemy, Inès; Blot, Stephane; Gijsbers, Rik; Cassano, Marco; Sampaolesi, Maurilio

2016-01-01

The Duchenne and Becker muscular dystrophies are caused by mutation of dystrophin gene and primarily affect skeletal and cardiac muscles. Cardiac involvement in dystrophic GRMD dogs has been demonstrated by electrocardiographic studies with the onset of a progressive cardiomyopathy similar to the cardiac disease in DMD patients. In this respect, GRMD is a useful model to explore cardiac and skeletal muscle pathogenesis and for developing new therapeutic protocols. Here we describe a protocol to convert GRMD canine fibroblasts isolated from heart and skin into induced cardiac-like myocytes (ciCLMs). We used a mix of transcription factors (GATA4, HAND2, TBX5, and MEF2C), known to be able to differentiate mouse and human somatic cells into ciCLMs. Exogenous gene expression was obtained using four lentiviral vectors carrying transcription factor genes and different resistance genes. Our data demonstrate a direct switch from fibroblast into ciCLMs with no activation of early cardiac genes. ciCLMs were unable to contract spontaneously, suggesting, differently from mouse and human cells, an incomplete differentiation process. However, when transplanted in neonatal hearts of SCID/Beige mice, ciCLMs participate in cardiac myogenesis.

Direct Reprogramming of Fibroblasts via a Chemically Induced XEN-like State.

PubMed

Li, Xiang; Liu, Defang; Ma, Yantao; Du, Xiaomin; Jing, Junzhan; Wang, Lipeng; Xie, Bingqing; Sun, Da; Sun, Shaoqiang; Jin, Xueqin; Zhang, Xu; Zhao, Ting; Guan, Jingyang; Yi, Zexuan; Lai, Weifeng; Zheng, Ping; Huang, Zhuo; Chang, Yanzhong; Chai, Zhen; Xu, Jun; Deng, Hongkui

2017-08-03

Direct lineage reprogramming, including with small molecules, has emerged as a promising approach for generating desired cell types. We recently found that during chemical induction of induced pluripotent stem cells (iPSCs) from mouse fibroblasts, cells pass through an extra-embryonic endoderm (XEN)-like state. Here, we show that these chemically induced XEN-like cells can also be induced to directly reprogram into functional neurons, bypassing the pluripotent state. The induced neurons possess neuron-specific expression profiles, form functional synapses in culture, and further mature after transplantation into the adult mouse brain. Using similar principles, we were also able to induce hepatocyte-like cells from the XEN-like cells. Cells in the induced XEN-like state were readily expandable over at least 20 passages and retained genome stability and lineage specification potential. Our study therefore establishes a multifunctional route for chemical lineage reprogramming and may provide a platform for generating a diverse range of cell types via application of this expandable XEN-like state. Copyright © 2017 Elsevier Inc. All rights reserved.

A multicellular view of cytokinesis in epithelial tissue.

PubMed

Herszterg, Sophie; Pinheiro, Diana; Bellaïche, Yohanns

2014-05-01

The study of cytokinesis in single-cell systems provided a wealth of knowledge on the molecular and biophysical mechanisms controlling daughter cell separation. In this review, we outline recent advances in the understanding of cytokinesis in epithelial tissues. These findings provide evidence for how the cytokinetic machinery adapts to a multicellular context and how the cytokinetic machinery is itself exploited by the tissue for the preservation of tissue function and architecture during proliferation. We propose that cytokinesis in epithelia should be viewed as a multicellular process, whereby the biochemical and mechanical interactions between the dividing cell and its neighbors are essential for successful daughter cell separation while defining epithelial tissue organization and preserving tissue integrity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Multicellular Computing Using Conjugation for Wiring

PubMed Central

Goñi-Moreno, Angel; Amos, Martyn; de la Cruz, Fernando

2013-01-01

Recent efforts in synthetic biology have focussed on the implementation of logical functions within living cells. One aim is to facilitate both internal “re-programming” and external control of cells, with potential applications in a wide range of domains. However, fundamental limitations on the degree to which single cells may be re-engineered have led to a growth of interest in multicellular systems, in which a “computation” is distributed over a number of different cell types, in a manner analogous to modern computer networks. Within this model, individual cell type perform specific sub-tasks, the results of which are then communicated to other cell types for further processing. The manner in which outputs are communicated is therefore of great significance to the overall success of such a scheme. Previous experiments in distributed cellular computation have used global communication schemes, such as quorum sensing (QS), to implement the “wiring” between cell types. While useful, this method lacks specificity, and limits the amount of information that may be transferred at any one time. We propose an alternative scheme, based on specific cell-cell conjugation. This mechanism allows for the direct transfer of genetic information between bacteria, via circular DNA strands known as plasmids. We design a multi-cellular population that is able to compute, in a distributed fashion, a Boolean XOR function. Through this, we describe a general scheme for distributed logic that works by mixing different strains in a single population; this constitutes an important advantage of our novel approach. Importantly, the amount of genetic information exchanged through conjugation is significantly higher than the amount possible through QS-based communication. We provide full computational modelling and simulation results, using deterministic, stochastic and spatially-explicit methods. These simulations explore the behaviour of one possible conjugation-wired cellular

Exploring the evolution of multicellularity in Saccharomyces cerevisiae under bacteria environment: An experimental phylogenetics approach.

PubMed

Quintero-Galvis, Julian F; Paleo-López, Rocío; Solano-Iguaran, Jaiber J; Poupin, María Josefina; Ledger, Thomas; Gaitan-Espitia, Juan Diego; Antoł, Andrzej; Travisano, Michael; Nespolo, Roberto F

2018-05-01

There have been over 25 independent unicellular to multicellular evolutionary transitions, which have been transformational in the complexity of life. All of these transitions likely occurred in communities numerically dominated by unicellular organisms, mostly bacteria. Hence, it is reasonable to expect that bacteria were involved in generating the ecological conditions that promoted the stability and proliferation of the first multicellular forms as protective units. In this study, we addressed this problem by analyzing the occurrence of multicellularity in an experimental phylogeny of yeasts ( Sacharomyces cerevisiae ) a model organism that is unicellular but can generate multicellular clusters under some conditions. We exposed a single ancestral population to periodic divergences, coevolving with a cocktail of environmental bacteria that were inoculated to the environment of the ancestor, and compared to a control (no bacteria). We quantified culturable microorganisms to the level of genera, finding up to 20 taxa (all bacteria) that competed with the yeasts during diversification. After 600 generations of coevolution, the yeasts produced two types of multicellular clusters: clonal and aggregative. Whereas clonal clusters were present in both treatments, aggregative clusters were only present under the bacteria treatment and showed significant phylogenetic signal. However, clonal clusters showed different properties if bacteria were present as follows: They were more abundant and significantly smaller than in the control. These results indicate that bacteria are important modulators of the occurrence of multicellularity, providing support to the idea that they generated the ecological conditions-promoting multicellularity.

Modeling a synthetic multicellular clock: Repressilators coupled by quorum sensing

PubMed Central

Garcia-Ojalvo, Jordi; Elowitz, Michael B.; Strogatz, Steven H.

2004-01-01

Diverse biochemical rhythms are generated by thousands of cellular oscillators that somehow manage to operate synchronously. In fields ranging from circadian biology to endocrinology, it remains an exciting challenge to understand how collective rhythms emerge in multicellular structures. Using mathematical and computational modeling, we study the effect of coupling through intercell signaling in a population of Escherichia coli cells expressing a synthetic biological clock. Our results predict that a diverse and noisy community of such genetic oscillators interacting through a quorum-sensing mechanism should self-synchronize in a robust way, leading to a substantially improved global rhythmicity in the system. As such, the particular system of coupled genetic oscillators considered here might be a good candidate to provide the first quantitative example of a synchronization transition in a population of biological oscillators. PMID:15256602

Modeling a synthetic multicellular clock: repressilators coupled by quorum sensing.

PubMed

Garcia-Ojalvo, Jordi; Elowitz, Michael B; Strogatz, Steven H

2004-07-27

Diverse biochemical rhythms are generated by thousands of cellular oscillators that somehow manage to operate synchronously. In fields ranging from circadian biology to endocrinology, it remains an exciting challenge to understand how collective rhythms emerge in multicellular structures. Using mathematical and computational modeling, we study the effect of coupling through intercell signaling in a population of Escherichia coli cells expressing a synthetic biological clock. Our results predict that a diverse and noisy community of such genetic oscillators interacting through a quorum-sensing mechanism should self-synchronize in a robust way, leading to a substantially improved global rhythmicity in the system. As such, the particular system of coupled genetic oscillators considered here might be a good candidate to provide the first quantitative example of a synchronization transition in a population of biological oscillators.

Modeling a synthetic multicellular clock: Repressilators coupled by quorum sensing

NASA Astrophysics Data System (ADS)

Garcia-Ojalvo, Jordi; Elowitz, Michael B.; Strogatz, Steven H.

2004-07-01

Diverse biochemical rhythms are generated by thousands of cellular oscillators that somehow manage to operate synchronously. In fields ranging from circadian biology to endocrinology, it remains an exciting challenge to understand how collective rhythms emerge in multicellular structures. Using mathematical and computational modeling, we study the effect of coupling through intercell signaling in a population of Escherichia coli cells expressing a synthetic biological clock. Our results predict that a diverse and noisy community of such genetic oscillators interacting through a quorum-sensing mechanism should self-synchronize in a robust way, leading to a substantially improved global rhythmicity in the system. As such, the particular system of coupled genetic oscillators considered here might be a good candidate to provide the first quantitative example of a synchronization transition in a population of biological oscillators.

Extracellular signaling and multicellularity in Bacillus subtilis.

PubMed

Shank, Elizabeth Anne; Kolter, Roberto

2011-12-01

Bacillus subtilis regulates its ability to differentiate into distinct, co-existing cell types in response to extracellular signaling molecules produced either by itself, or present in its environment. The production of molecules by B. subtilis cells, as well as their response to these signals, is not uniform across the population. There is specificity and heterogeneity both within genetically identical populations as well as at the strain-level and species-level. This review will discuss how extracellular signaling compounds influence B. subtilis multicellularity with regard to matrix-producing cannibal differentiation, germination, and swarming behavior, as well as the specificity of the quorum-sensing peptides ComX and CSF. It will also highlight how imaging mass spectrometry can aid in identifying signaling compounds and contribute to our understanding of the functional relationship between such compounds and multicellular behavior. Copyright © 2011 Elsevier Ltd. All rights reserved.

Detecting tree-like multicellular life on extrasolar planets.

PubMed

Doughty, Christopher E; Wolf, Adam

2010-11-01

Over the next two decades, NASA and ESA are planning a series of space-based observatories to find Earth-like planets and determine whether life exists on these planets. Previous studies have assessed the likelihood of detecting life through signs of biogenic gases in the atmosphere or a red edge. Biogenic gases and the red edge could be signs of either single-celled or multicellular life. In this study, we propose a technique with which to determine whether tree-like multicellular life exists on extrasolar planets. For multicellular photosynthetic organisms on Earth, competition for light and the need to transport water and nutrients has led to a tree-like body plan characterized by hierarchical branching networks. This design results in a distinct bidirectional reflectance distribution function (BRDF) that causes differing reflectance at different sun/view geometries. BRDF arises from the changing visibility of the shadows cast by objects, and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star. We used a semi-empirical BRDF model to simulate vegetation reflectance at different planetary phase angles and both simulated and real cloud cover to calculate disk and rotation-averaged planetary albedo for a vegetated and non-vegetated planet with abundant liquid water. We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet. Depending on how accurately planetary cloud cover can be resolved and the capabilities of the coronagraph to resolve exoplanets, this technique could theoretically detect tree-like multicellular life on exoplanets in 50 stellar systems.

Cellular Particle Dynamics simulation of biomechanical relaxation processes of multi-cellular systems

NASA Astrophysics Data System (ADS)

McCune, Matthew; Kosztin, Ioan

2013-03-01

Cellular Particle Dynamics (CPD) is a theoretical-computational-experimental framework for describing and predicting the time evolution of biomechanical relaxation processes of multi-cellular systems, such as fusion, sorting and compression. In CPD, cells are modeled as an ensemble of cellular particles (CPs) that interact via short range contact interactions, characterized by an attractive (adhesive interaction) and a repulsive (excluded volume interaction) component. The time evolution of the spatial conformation of the multicellular system is determined by following the trajectories of all CPs through numerical integration of their equations of motion. Here we present CPD simulation results for the fusion of both spherical and cylindrical multi-cellular aggregates. First, we calibrate the relevant CPD model parameters for a given cell type by comparing the CPD simulation results for the fusion of two spherical aggregates to the corresponding experimental results. Next, CPD simulations are used to predict the time evolution of the fusion of cylindrical aggregates. The latter is relevant for the formation of tubular multi-cellular structures (i.e., primitive blood vessels) created by the novel bioprinting technology. Work supported by NSF [PHY-0957914]. Computer time provided by the University of Missouri Bioinformatics Consortium.

Observation of multicellular spinning behavior of Proteus mirabilis by atomic force microscopy and multifunctional microscopy.

PubMed

Liu, Yanxia; Deng, Yuanxin; Luo, Shuxiu; Deng, Yu; Guo, Linming; Xu, Weiwei; Liu, Lei; Liu, Junkang

2014-01-01

This study aimed to observe the multicellular spinning behavior of Proteus mirabilis by atomic force microscopy (AFM) and multifunctional microscopy in order to understand the mechanism underlying this spinning movement and its biological significance. Multifunctional microscopy with charge-coupled device (CCD) and real-time AFM showed changes in cell structure and shape of P. mirabilis during multicellular spinning movement. Specifically, the morphological characteristics of P. mirabilis, multicellular spinning dynamics, and unique movement were observed. Our findings indicate that the multicellular spinning behavior of P. mirabilis may be used to collect nutrients, perform colonization, and squeeze out competitors. The movement characteristics of P. mirabilis are vital to the organism's biological adaptability to the surrounding environment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Multicellularity arose several times in the evolution of eukaryotes (response to DOI 10.1002/bies.201100187).

PubMed

Parfrey, Laura Wegener; Lahr, Daniel J G

2013-04-01

The cellular slime mold Dictyostelium has cell-cell connections similar in structure, function, and underlying molecular mechanisms to animal epithelial cells. These similarities form the basis for the proposal that multicellularity is ancestral to the clade containing animals, fungi, and Amoebozoa (including Dictyostelium): Amorphea (formerly "unikonts"). This hypothesis is intriguing and if true could precipitate a paradigm shift. However, phylogenetic analyses of two key genes reveal patterns inconsistent with a single origin of multicellularity. A single origin in Amorphea would also require loss of multicellularity in each of the many unicellular lineages within this clade. Further, there are numerous other origins of multicellularity within eukaryotes, including three within Amorphea, that are not characterized by these structural and mechanistic similarities. Instead, convergent evolution resulting from similar selective pressures for forming multicellular structures with motile and differentiated cells is the most likely explanation for the observed similarities between animal and dictyostelid cell-cell connections. Copyright © 2013 WILEY Periodicals, Inc.

Emergent multicellular life cycles in filamentous bacteria owing to density-dependent population dynamics.

PubMed

Rossetti, Valentina; Filippini, Manuela; Svercel, Miroslav; Barbour, A D; Bagheri, Homayoun C

2011-12-07

Filamentous bacteria are the oldest and simplest known multicellular life forms. By using computer simulations and experiments that address cell division in a filamentous context, we investigate some of the ecological factors that can lead to the emergence of a multicellular life cycle in filamentous life forms. The model predicts that if cell division and death rates are dependent on the density of cells in a population, a predictable cycle between short and long filament lengths is produced. During exponential growth, there will be a predominance of multicellular filaments, while at carrying capacity, the population converges to a predominance of short filaments and single cells. Model predictions are experimentally tested and confirmed in cultures of heterotrophic and phototrophic bacterial species. Furthermore, by developing a formulation of generation time in bacterial populations, it is shown that changes in generation time can alter length distributions. The theory predicts that given the same population growth curve and fitness, species with longer generation times have longer filaments during comparable population growth phases. Characterization of the environmental dependence of morphological properties such as length, and the number of cells per filament, helps in understanding the pre-existing conditions for the evolution of developmental cycles in simple multicellular organisms. Moreover, the theoretical prediction that strains with the same fitness can exhibit different lengths at comparable growth phases has important implications. It demonstrates that differences in fitness attributed to morphology are not the sole explanation for the evolution of life cycles dominated by multicellularity.

Enhanced Keratinocyte Proliferation and Migration in Co-culture with Fibroblasts

PubMed Central

Wang, Zhenxiang; Wang, Ying; Farhangfar, Farhang; Zimmer, Monica; Zhang, Yongxin

2012-01-01

Wound healing is primarily controlled by the proliferation and migration of keratinocytes and fibroblasts as well as the complex interactions between these two cell types. To investigate the interactions between keratinocytes and fibroblasts and the effects of direct cell-to-cell contact on the proliferation and migration of keratinocytes, keratinocytes and fibroblasts were stained with different fluorescence dyes and co-cultured with or without transwells. During the early stage (first 5 days) of the culture, the keratinocytes in contact with fibroblasts proliferated significantly faster than those not in contact with fibroblasts, but in the late stage (11th to 15th day), keratinocyte growth slowed down in all cultures unless EGF was added. In addition, keratinocyte migration was enhanced in co-cultures with fibroblasts in direct contact, but not in the transwells. Furthermore, the effects of the fibroblasts on keratinocyte migration and growth at early culture stage correlated with heparin-binding EGF-like growth factor (HB-EGF), IL-1α and TGF-β1 levels in the cultures where the cells were grown in direct contact. These effects were inhibited by anti-HB-EGF, anti-IL-1α and anti-TGF-β1 antibodies and anti-HB-EGF showed the greatest inhibition. Co-culture of keratinocytes and IL-1α and TGF-β1 siRNA-transfected fibroblasts exhibited a significant reduction in HB-EGF production and keratinocyte proliferation. These results suggest that contact with fibroblasts stimulates the migration and proliferation of keratinocytes during wound healing, and that HB-EGF plays a central role in this process and can be up-regulated by IL-1α and TGF-β1, which also regulate keratinocyte proliferation differently during the early and late stage. PMID:22911722

Multicellular contractility contributes to the emergence of mesothelioma nodules

NASA Astrophysics Data System (ADS)

Czirok, Andras

Malignant pleural mesothelioma (MPM) nodules arise from the mesothelial lining of the pleural cavity by a poorly understood mechanism. We demonstrate that macroscopic multicellular aggregates, reminiscent of the MPM nodules found in patients, develop when MPM cell lines are cultured at high cell densities for several weeks. Surprisingly, the nodule-like aggregates do not arise by excessive local cell proliferation, but by myosin II-driven cell contractility. Contractile nodules contain prominent actin cables that can span several cells. Several features of the in vitro MPM nodule development can be explained by a computational model that assumes uniform and steady intercellular contractile forces within a monolayer of cells, and a mechanical load-dependent lifetime of cell-cell contacts. The model behaves as a self-tensioned Maxwell fluid and exhibits an instability that leads to pattern formation. Altogether, our findings suggest that inhibition of the actomyosin system may provide a hitherto not utilized therapeutic approach to affect MPM growth. NIH R01-GM102801.

MiR-590 Promotes Transdifferentiation of Porcine and Human Fibroblasts Toward a Cardiomyocyte-Like Fate by Directly Repressing Specificity Protein 1.

PubMed

Singh, Vivek P; Mathison, Megumi; Patel, Vivekkumar; Sanagasetti, Deepthi; Gibson, Brian W; Yang, Jianchang; Rosengart, Todd K

2016-11-10

Reprogramming of cardiac fibroblasts into induced cardiomyocyte-like cells represents a promising potential new therapy for treating heart disease, inducing significant improvements in postinfarct ventricular function in rodent models. Because reprogramming factors effective in transdifferentiating rodent cells are not sufficient to reprogram human cells, we sought to identify reprogramming factors potentially applicable to human studies. Lentivirus vectors expressing Gata4, Mef2c, and Tbx5 (GMT); Hand2 (H), Myocardin (My), or microRNA (miR)-590 were administered to rat, porcine, and human cardiac fibroblasts in vitro. induced cardiomyocyte-like cell production was then evaluated by assessing expression of the cardiomyocyte marker, cardiac troponin T (cTnT), whereas signaling pathway studies were performed to identify reprogramming factor targets. GMT administration induced cTnT expression in ≈6% of rat fibroblasts, but failed to induce cTnT expression in porcine or human cardiac fibroblasts. Addition of H/My and/or miR-590 to GMT administration resulted in cTNT expression in ≈5% of porcine and human fibroblasts and also upregulated the expression of the cardiac genes, MYH6 and TNNT2. When cocultured with murine cardiomyocytes, cTnT-expressing porcine cardiac fibroblasts exhibited spontaneous contractions. Administration of GMT plus either H/My or miR-590 alone also downregulated fibroblast genes COL1A1 and COL3A1. miR-590 was shown to directly suppress the zinc finger protein, specificity protein 1 (Sp1), which was able to substitute for miR-590 in inducing cellular reprogramming. These data support porcine studies as a surrogate for testing human cardiac reprogramming, and suggest that miR-590-mediated repression of Sp1 represents an alternative pathway for enhancing human cardiac cellular reprogramming. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Developing the Self-Directed Learning Instructional Model to Enhance English Reading Ability and Self-Directed Learning of Undergraduate Students

ERIC Educational Resources Information Center

Wichadee, Saovapa

2011-01-01

The purposes of this study were to develop the instructional model for enhancing self-directed learning skills of Bangkok University students, study the impacts of the model on their English reading comprehension and self-directed learning ability as well as explore their opinion towards self-directed learning. The model development process…

Genome duplication and mutations in ACE2 cause multicellular, fast-sedimenting phenotypes in evolved Saccharomyces cerevisiae

PubMed Central

Oud, Bart; Guadalupe-Medina, Victor; Nijkamp, Jurgen F.; de Ridder, Dick; Pronk, Jack T.; van Maris, Antonius J. A.; Daran, Jean-Marc

2013-01-01

Laboratory evolution of the yeast Saccharomyces cerevisiae in bioreactor batch cultures yielded variants that grow as multicellular, fast-sedimenting clusters. Knowledge of the molecular basis of this phenomenon may contribute to the understanding of natural evolution of multicellularity and to manipulating cell sedimentation in laboratory and industrial applications of S. cerevisiae. Multicellular, fast-sedimenting lineages obtained from a haploid S. cerevisiae strain in two independent evolution experiments were analyzed by whole genome resequencing. The two evolved cell lines showed different frameshift mutations in a stretch of eight adenosines in ACE2, which encodes a transcriptional regulator involved in cell cycle control and mother-daughter cell separation. Introduction of the two ace2 mutant alleles into the haploid parental strain led to slow-sedimenting cell clusters that consisted of just a few cells, thus representing only a partial reconstruction of the evolved phenotype. In addition to single-nucleotide mutations, a whole-genome duplication event had occurred in both evolved multicellular strains. Construction of a diploid reference strain with two mutant ace2 alleles led to complete reconstruction of the multicellular-fast sedimenting phenotype. This study shows that whole-genome duplication and a frameshift mutation in ACE2 are sufficient to generate a fast-sedimenting, multicellular phenotype in S. cerevisiae. The nature of the ace2 mutations and their occurrence in two independent evolution experiments encompassing fewer than 500 generations of selective growth suggest that switching between unicellular and multicellular phenotypes may be relevant for competitiveness of S. cerevisiae in natural environments. PMID:24145419

Pericellular Versican Regulates the Fibroblast-Myofibroblast Transition

PubMed Central

Hattori, Noriko; Carrino, David A.; Lauer, Mark E.; Vasanji, Amit; Wylie, James D.; Nelson, Courtney M.; Apte, Suneel S.

2011-01-01

The cell and its glycosaminoglycan-rich pericellular matrix (PCM) comprise a functional unit. Because modification of PCM influences cell behavior, we investigated molecular mechanisms that regulate PCM volume and composition. In fibroblasts and other cells, aggregates of hyaluronan and versican are found in the PCM. Dermal fibroblasts from Adamts5−/− mice, which lack a versican-degrading protease, ADAMTS5, had reduced versican proteolysis, increased PCM, altered cell shape, enhanced α-smooth muscle actin (SMA) expression and increased contractility within three-dimensional collagen gels. The myofibroblast-like phenotype was associated with activation of TGFβ signaling. We tested the hypothesis that fibroblast-myofibroblast transition in Adamts5−/− cells resulted from versican accumulation in PCM. First, we noted that versican overexpression in human dermal fibroblasts led to increased SMA expression, enhanced contractility, and increased Smad2 phosphorylation. In contrast, dermal fibroblasts from Vcan haploinsufficient (Vcanhdf/+) mice had reduced contractility relative to wild type fibroblasts. Using a genetic approach to directly test if myofibroblast transition in Adamts5−/− cells resulted from increased PCM versican content, we generated Adamts5−/−;Vcanhdf/+ mice and isolated their dermal fibroblasts for comparison with dermal fibroblasts from Adamts5−/− mice. In Adamts5−/− fibroblasts, Vcan haploinsufficiency or exogenous ADAMTS5 restored normal fibroblast contractility. These findings demonstrate that altering PCM versican content through proteolytic activity of ADAMTS5 profoundly influenced the dermal fibroblast phenotype and may regulate a phenotypic continuum between the fibroblast and its alter ego, the myofibroblast. We propose that a physiological function of ADAMTS5 in dermal fibroblasts is to maintain optimal versican content and PCM volume by continually trimming versican in hyaluronan-versican aggregates. PMID:21828051

Rho A and the Rho kinase pathway regulate fibroblast contraction: Enhanced contraction in constitutively active Rho A fibroblast cells

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

Nobe, Koji, E-mail: kojinobe@pharm.showa-u.ac.jp; Nobe, Hiromi; Department of Physical Therapy, Bunkyo-Gakuin University

Research highlights: {yields} Mechanisms of fibroblast cell contraction in collagen matrix. {yields} Assessed an isometric force development using 3D-reconstituted-fibroblast fiber. {yields} Constitutively active Rho A induced the over-contraction of fibroblast cells. {yields} Rho A and Rho kinase pathway has a central role in fibroblast cell contraction. -- Abstract: Fibroblast cells play a central role in the proliferation phase of wound healing processes, contributing to force development. The intracellular signaling pathways regulating this non-muscle contraction are only partially understood. To study the relations between Rho A and contractile responses, constitutively active Rho A (CA-Rho A) fibroblast cells were reconstituted into fibersmore » and the effects of calf serum (CS) on isometric force were studied. CS-induced force in CA-Rho A fibroblast fibers was twice as large as that in wild type (NIH 3T3) fibroblast fibers. During this response, the translocation of Rho A from the cytosol to the membrane was detected by Rho A activity assays and Western blot analysis. Pre-treatment with a Rho specific inhibitor (C3-exoenzyme) suppressed translocation as well as contraction. These results indicate that Rho A activation is essential for fibroblast contraction. The Rho kinase inhibitor ( (Y27632)) inhibited both NIH 3T3 and CA-Rho A fibroblast fiber contractions. Activation of Rho A is thus directly coupled with Rho kinase activity. We conclude that the translocation of Rho A from the cytosol to the membrane and the Rho kinase pathway can regulate wound healing processes mediated by fibroblast contraction.« less

Engineering cellular fibers for musculoskeletal soft tissues using directed self-assembly.

PubMed

Schiele, Nathan R; Koppes, Ryan A; Chrisey, Douglas B; Corr, David T

2013-05-01

Engineering strategies guided by developmental biology may enhance and accelerate in vitro tissue formation for tissue engineering and regenerative medicine applications. In this study, we looked toward embryonic tendon development as a model system to guide our soft tissue engineering approach. To direct cellular self-assembly, we utilized laser micromachined, differentially adherent growth channels lined with fibronectin. The micromachined growth channels directed human dermal fibroblast cells to form single cellular fibers, without the need for a provisional three-dimensional extracellular matrix or scaffold to establish a fiber structure. Therefore, the resulting tissue structure and mechanical characteristics were determined solely by the cells. Due to the self-assembly nature of this approach, the growing fibers exhibit some key aspects of embryonic tendon development, such as high cellularity, the rapid formation (within 24 h) of a highly organized and aligned cellular structure, and the expression of cadherin-11 (indicating direct cell-to-cell adhesions). To provide a dynamic mechanical environment, we have also developed and characterized a method to apply precise cyclic tensile strain to the cellular fibers as they develop. After an initial period of cellular fiber formation (24 h postseeding), cyclic strain was applied for 48 h, in 8-h intervals, with tensile strain increasing from 0.7% to 1.0%, and at a frequency of 0.5 Hz. Dynamic loading dramatically increased cellular fiber mechanical properties with a nearly twofold increase in both the linear region stiffness and maximum load at failure, thereby demonstrating a mechanism for enhancing cellular fiber formation and mechanical properties. Tissue engineering strategies, designed to capture key aspects of embryonic development, may provide unique insight into accelerated maturation of engineered replacement tissue, and offer significant advances for regenerative medicine applications in tendon

Characterization of interleukin-4-stimulated nasal polyp fibroblasts.

PubMed

Steinke, John W; Crouse, Charles D; Bradley, Dewayne; Hise, Kathleen; Lynch, Kevin; Kountakis, Stilianos E; Borish, Larry

2004-02-01

Chronic hyperplastic eosinophilic sinusitis is an inflammatory disease that results in the accumulation of eosinophils, fibroblasts, mast cells, and goblet cells at the site of injury. A common feature of this disease is the presence of nasal polyposis (NP). The current studies were designed to assess the contribution of interleukin (IL)-4 to fibroblast-mediated inflammation in chronic hyperplastic eosinophilic sinusitis/NP. In addition, we hypothesized that cysteinyl leukotrienes (CysLT) may directly influence fibroblast-mediated fibrotic and remodeling pathways in this disorder. Fibroblasts were isolated from NP tissue. All fibroblast lines expressed the IL-4 receptor. IL-4 induced changes in mRNA and protein expression of fibrotic (transforming growth factor-beta1 and -beta2) and inflammatory cytokines and chemokines (IL-6 and CCL11) by fibroblasts as measured by semiquantitative and quantitative polymerase chain reaction, RNase protection assay, and enzyme-linked immunosorbent assay. The expression of CysLT and other proinflammatory lipid receptors on fibroblasts was evaluated. CysLT1 and CysLT2 receptors were not expressed on fibroblasts; however, LPA(1) receptor was constitutively expressed and LPA(2) receptor expression was upregulated by IL-4. The metabolic cascade involved in CysLT synthesis was not expressed in fibroblasts and could not be induced by IL-4 treatment.

Inhibition of TGFβ signaling increases direct conversion of fibroblasts to induced cardiomyocytes.

PubMed

Ifkovits, Jamie L; Addis, Russell C; Epstein, Jonathan A; Gearhart, John D

2014-01-01

Recent studies have been successful at utilizing ectopic expression of transcription factors to generate induced cardiomyocytes (iCMs) from fibroblasts, albeit at a low frequency in vitro. This work investigates the influence of small molecules that have been previously reported to improve differentiation to cardiomyocytes as well as reprogramming to iPSCs in conjunction with ectopic expression of the transcription factors Hand2, Nkx2.5, Gata4, Mef2C, and Tbx5 on the conversion to functional iCMs. We utilized a reporter system in which the calcium indicator GCaMP is driven by the cardiac Troponin T promoter to quantify iCM yield. The TGFβ inhibitor, SB431542 (SB), was identified as a small molecule capable of increasing the conversion of both mouse embryonic fibroblasts and adult cardiac fibroblasts to iCMs up to ∼5 fold. Further characterization revealed that inhibition of TGFβ by SB early in the reprogramming process led to the greatest increase in conversion of fibroblasts to iCMs in a dose-responsive manner. Global transcriptional analysis at Day 3 post-induction of the transcription factors revealed an increased expression of genes associated with the development of cardiac muscle in the presence of SB compared to the vehicle control. Incorporation of SB in the reprogramming process increases the efficiency of iCM generation, one of the major goals necessary to enable the use of iCMs for discovery-based applications and for the clinic.

Inhibition of TGFβ Signaling Increases Direct Conversion of Fibroblasts to Induced Cardiomyocytes

PubMed Central

Ifkovits, Jamie L.; Addis, Russell C.; Epstein, Jonathan A.; Gearhart, John D.

2014-01-01

Recent studies have been successful at utilizing ectopic expression of transcription factors to generate induced cardiomyocytes (iCMs) from fibroblasts, albeit at a low frequency in vitro. This work investigates the influence of small molecules that have been previously reported to improve differentiation to cardiomyocytes as well as reprogramming to iPSCs in conjunction with ectopic expression of the transcription factors Hand2, Nkx2.5, Gata4, Mef2C, and Tbx5 on the conversion to functional iCMs. We utilized a reporter system in which the calcium indicator GCaMP is driven by the cardiac Troponin T promoter to quantify iCM yield. The TGFβ inhibitor, SB431542 (SB), was identified as a small molecule capable of increasing the conversion of both mouse embryonic fibroblasts and adult cardiac fibroblasts to iCMs up to ∼5 fold. Further characterization revealed that inhibition of TGFβ by SB early in the reprogramming process led to the greatest increase in conversion of fibroblasts to iCMs in a dose-responsive manner. Global transcriptional analysis at Day 3 post-induction of the transcription factors revealed an increased expression of genes associated with the development of cardiac muscle in the presence of SB compared to the vehicle control. Incorporation of SB in the reprogramming process increases the efficiency of iCM generation, one of the major goals necessary to enable the use of iCMs for discovery-based applications and for the clinic. PMID:24586958

Sponge cell reaggregation: Cellular structure and morphogenetic potencies of multicellular aggregates.

PubMed

Lavrov, Andrey I; Kosevich, Igor A

2016-02-01

Sponges (phylum Porifera) are one of the most ancient extant multicellular animals and can provide valuable insights into origin and early evolution of Metazoa. High plasticity of cell differentiations and anatomical structure is characteristic feature of sponges. Present study deals with sponge cell reaggregation after dissociation as the most outstanding case of sponge plasticity. Dynamic of cell reaggregation and structure of multicellular aggregates of three demosponge species (Halichondria panicea (Pallas, 1766), Haliclona aquaeductus (Sсhmidt, 1862), and Halisarca dujardinii Johnston, 1842) were studied. Sponge tissue dissociation was performed mechanically. Resulting cell suspensions were cultured at 8-10°C for at least 5 days. Structure of multicellular aggregates was studied by light, transmission and scanning electron microscopy. Studied species share common stages of cell reaggregation-primary multicellular aggregates, early-stage primmorphs and primmorphs, but the rate of reaggregation varies considerably among species. Only cells of H. dujardinii are able to reconstruct functional and viable sponge after primmorphs formation. Sponge reconstruction in this species occurs due to active cell locomotion. Development of H. aquaeductus and H. panicea cells ceases at the stages of early primmorphs and primmorphs, respectively. Development of aggregates of these species is most likely arrested due to immobility of the majority of cells inside them. However, the inability of certain sponge species to reconstruct functional and viable individuals during cell reaggregation may be not a permanent species-specific characteristic, but depends on various factors, including the stage of the life cycle and experimental conditions. © 2016 Wiley Periodicals, Inc.

Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri

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

Prochnik, Simon E.; Umen, James; Nedelcu, Aurora

2010-07-01

Analysis of the Volvox carteri genome reveals that this green alga's increased organismal complexity and multicellularity are associated with modifications in protein families shared with its unicellular ancestor, and not with large-scale innovations in protein coding capacity. The multicellular green alga Volvox carteri and its morphologically diverse close relatives (the volvocine algae) are uniquely suited for investigating the evolution of multicellularity and development. We sequenced the 138 Mb genome of V. carteri and compared its {approx}14,500 predicted proteins to those of its unicellular relative, Chlamydomonas reinhardtii. Despite fundamental differences in organismal complexity and life history, the two species have similarmore » protein-coding potentials, and few species-specific protein-coding gene predictions. Interestingly, volvocine algal-specific proteins are enriched in Volvox, including those associated with an expanded and highly compartmentalized extracellular matrix. Our analysis shows that increases in organismal complexity can be associated with modifications of lineage-specific proteins rather than large-scale invention of protein-coding capacity.« less

Noise-induced effects on multicellular biopacemaker spontaneous activity: Differences between weak and strong pacemaker cells

NASA Astrophysics Data System (ADS)

Aghighi, Alireza; Comtois, Philippe

2017-09-01

Self-organization of spontaneous activity of a network of active elements is important to the general theory of reaction-diffusion systems as well as for pacemaking activity to initiate beating of the heart. Monolayer cultures of neonatal rat ventricular myocytes, consisting of resting and pacemaker cells, exhibit spontaneous activation of their electrical activity. Similarly, one proposed approach to the development of biopacemakers as an alternative to electronic pacemakers for cardiac therapy is based on heterogeneous cardiac cells with resting and spontaneously beating phenotypes. However, the combined effect of pacemaker characteristics, density, and spatial distribution of the pacemaker cells on spontaneous activity is unknown. Using a simple stochastic pattern formation algorithm, we previously showed a clear nonlinear dependency of spontaneous activity (occurrence and amplitude of spontaneous period) on the spatial patterns of pacemaker cells. In this study, we show that this behavior is dependent on the pacemaker cell characteristics, with weaker pacemaker cells requiring higher density and larger clusters to sustain multicellular activity. These multicellular structures also demonstrated an increased sensitivity to voltage noise that favored spontaneous activity at lower density while increasing temporal variation in the period of activity. This information will help researchers overcome the current limitations of biopacemakers.

Emotional consequences of collective action participation: differentiating self-directed and outgroup-directed emotions.

PubMed

Becker, Julia C; Tausch, Nicole; Wagner, Ulrich

2011-12-01

The present research examines the emotional and behavioral consequences of collective action participation. It demonstrates that "positive" and "negative" emotions can be experienced simultaneously as a result of collective action participation, yet it is important to distinguish outgroup-directed from self-directed emotions. Results of two experiments (N = 71 and N = 101) that manipulated participation in collective action illustrate that whereas collective action participants experience more outgroup-directed anger and contempt, they feel more self-directed positive affect. Furthermore, collective action participation predicted willingness to engage in moderate and radical collective actions in the future. These relations were mediated by outgroup-directed, but not by self-directed, emotions, suggesting that outgroup-directed rather than self-directed emotions play a crucial role in the maintenance of protest behavior. Theoretical and practical implications of these findings are discussed.

Papillary fibroblasts differentiate into reticular fibroblasts after prolonged in vitro culture.

PubMed

Janson, David; Saintigny, Gaëlle; Mahé, Christian; El Ghalbzouri, Abdoelwaheb

2013-01-01

The dermis can be divided into two morphologically different layers: the papillary and reticular dermis. Fibroblasts isolated from these layers behave differently when cultured in vitro. During skin ageing, the papillary dermis decreases in volume. Based on the functional differences in vitro, it is hypothesized that the loss of papillary fibroblasts contributes to skin ageing. In this study, we aimed to mimic certain aspects of skin ageing by using high-passage cultures of reticular and papillary fibroblasts and investigated the effect of these cells on skin morphogenesis in reconstructed human skin equivalents. Skin equivalents generated with reticular fibroblasts showed a reduced terminal differentiation and fewer proliferating basal keratinocytes. Aged in vitro papillary fibroblasts had increased expression of biomarkers specific to reticular fibroblasts. The phenotype and morphology of skin equivalents generated with high-passage papillary fibroblasts resembled that of reticular fibroblasts. This demonstrates that papillary fibroblasts can differentiate into reticular fibroblasts in vitro. Therefore, we hypothesize that papillary fibroblasts represent an undifferentiated phenotype, while reticular fibroblasts represent a more differentiated population. The differentiation process could be a new target for anti-skin-ageing strategies. © 2013 John Wiley & Sons A/S.

Geometry, packing, and evolutionary paths to increased multicellular size

NASA Astrophysics Data System (ADS)

Jacobeen, Shane; Graba, Elyes C.; Brandys, Colin G.; Day, Thomas C.; Ratcliff, William C.; Yunker, Peter J.

2018-05-01

The evolutionary transition to multicellularity transformed life on earth, heralding the evolution of large, complex organisms. Recent experiments demonstrated that laboratory-evolved multicellular "snowflake yeast" readily overcome the physical barriers that limit cluster size by modifying cellular geometry [Jacobeen et al., Nat. Phys. 14, 286 (2018), 10.1038/s41567-017-0002-y]. However, it is unclear why this route to large size is observed, rather than an evolved increase in intercellular bond strength. Here, we use a geometric model of the snowflake yeast growth form to examine the geometric efficiency of increasing size by modifying geometry and bond strength. We find that changing geometry is a far more efficient route to large size than evolving increased intercellular adhesion. In fact, increasing cellular aspect ratio is on average ˜13 times more effective than increasing bond strength at increasing the number of cells in a cluster. Modifying other geometric parameters, such as the geometric arrangement of mother and daughter cells, also had larger effects on cluster size than increasing bond strength. Simulations reveal that as cells reproduce, internal stress in the cluster increases rapidly; thus, increasing bond strength provides diminishing returns in cluster size. Conversely, as cells become more elongated, cellular packing density within the cluster decreases, which substantially decreases the rate of internal stress accumulation. This suggests that geometrically imposed physical constraints may have been a key early selective force guiding the emergence of multicellular complexity.

Human serum reduces mitomycin-C cytotoxicity in human tenon's fibroblasts.

PubMed

Crowston, Jonathan G; Wang, Xiao Y; Khaw, Peng T; Zoellner, Hans; Healey, Paul R

2006-03-01

To determine the effect of human serum factors on mitomycin-C (MMC) cytotoxicity in cultured human subconjunctival Tenon's capsule fibroblasts. Fibroblast monolayers were treated with 5-minute applications of mitomycin-C (0.4 mg/mL) and incubated in culture medium with or without additional human serum. Fibroblast apoptosis was quantified by direct cell counts based on nuclear morphology, flow cytometry with annexin-V/propidium iodide, and a lactate dehydrogenase release assay. The number of viable fibroblasts and fibroblast proliferation were measured with a colorimetric MTT assay and by bromodeoxyuridine (BrdU) labeling. Mitomycin-C induced significant levels of fibroblast apoptosis. The addition of human serum resulted in a 40% reduction in MMC-induced fibroblast apoptosis (range, 31.3%-55.3%; P = 0.021) as determined by nuclear morphology and a 32.4% reduction measured by annexin-V/PI. There was a corresponding dose-dependent increase in the number of viable fibroblasts. Serum did not restore proliferation in MMC-treated fibroblasts. Factors present in human serum reduce MMC cytotoxicity in cultured human Tenon's fibroblasts. Human serum increased the number of viable fibroblasts by inhibiting MMC-induced fibroblast apoptosis. Serum factors access aqueous humor after trabeculectomy and may therefore influence the clinical outcome of MMC treatment.

Processing and characterization of multi-cellular monolithic bioceramics for bone regenerative scaffolds

NASA Astrophysics Data System (ADS)

Ari-Wahjoedi, Bambang; Ginta, Turnad Lenggo; Parman, Setyamartana; Abustaman, Mohd Zikri Ahmad

2014-10-01

Multicellular monolithic ceramic body is a ceramic material which has many gas or liquid passages partitioned by thin walls throughout the bulk material. There are many currently known advanced industrial applications of multicellular ceramics structures i.e. as supports for various catalysts, electrode support structure for solid oxide fuel cells, refractories, electric/electronic materials, aerospace vehicle re-entry heat shields and biomaterials for dental as well as orthopaedic implants by naming only a few. Multicellular ceramic bodies are usually made of ceramic phases such as mullite, cordierite, aluminum titanate or pure oxides such as silica, zirconia and alumina. What make alumina ceramics is excellent for the above functions are the intrinsic properties of alumina which are hard, wear resistant, excellent dielectric properties, resists strong acid and alkali attacks at elevated temperatures, good thermal conductivities, high strength and stiffness as well as biocompatible. In this work the processing technology leading to truly multicellular monolithic alumina ceramic bodies and their characterization are reported. Ceramic slip with 66 wt.% solid loading was found to be optimum as impregnant to the polyurethane foam template. Mullitic ceramic composite of alumina-sodium alumino disilicate-Leucite-like phases with bulk and true densities of 0.852 and 1.241 g cm-3 respectively, pore linear density of ±35 cm-1, linear and bulk volume shrinkages of 7-16% and 32 vol.% were obtained. The compressive strength and elastic modulus of the bioceramics are ≈0.5-1.0 and ≈20 MPa respectively.

Perceptions of self-determination by special education and rehabilitation practitioners based on viewing a self-directed IEP versus an external-directed IEP meeting.

PubMed

Branding, Dave; Bates, Paul; Miner, Craig

2009-01-01

This study investigated perception of self-determination by special education and rehabilitation practitioners following their exposure to a videotaped simulation of a self-directed IEP meeting and an external-directed IEP meeting involving an adolescent with mild mental retardation. Groups of special education practitioners and rehabilitation practitioners did not differ from each other in their perceptions of self-determination before or after viewing either the self-directed or external-directed IEP meeting simulation. However, both groups of respondents had higher perceptions of the self-determination capability of the confederate student when they viewed her in a self-directed meeting. In addition, respondents consistently rated the self-directed meeting simulation as being of higher overall quality than the external-directed meeting. Results are discussed in relation to practitioner recommendations and future research in regard to the development and enabling of self-determination skills involving persons with disabilities.

Imaging of bacterial multicellular behaviour in biofilms in liquid by atmospheric scanning electron microscopy

PubMed Central

Sugimoto, Shinya; Okuda, Ken-ichi; Miyakawa, Reina; Sato, Mari; Arita-Morioka, Ken-ichi; Chiba, Akio; Yamanaka, Kunitoshi; Ogura, Teru; Mizunoe, Yoshimitsu; Sato, Chikara

2016-01-01

Biofilms are complex communities of microbes that attach to biotic or abiotic surfaces causing chronic infectious diseases. Within a biofilm, microbes are embedded in a self-produced soft extracellular matrix (ECM), which protects them from the host immune system and antibiotics. The nanoscale visualisation of delicate biofilms in liquid is challenging. Here, we develop atmospheric scanning electron microscopy (ASEM) to visualise Gram-positive and -negative bacterial biofilms immersed in aqueous solution. Biofilms cultured on electron-transparent film were directly imaged from below using the inverted SEM, allowing the formation of the region near the substrate to be studied at high resolution. We visualised intercellular nanostructures and the exocytosis of membrane vesicles, and linked the latter to the trafficking of cargos, including cytoplasmic proteins and the toxins hemolysin and coagulase. A thick dendritic nanotube network was observed between microbes, suggesting multicellular communication in biofilms. A universal immuno-labelling system was developed for biofilms and tested on various examples, including S. aureus biofilms. In the ECM, fine DNA and protein networks were visualised and the precise distribution of protein complexes was determined (e.g., straight curli, flagella, and excreted cytoplasmic molecular chaperones). Our observations provide structural insights into bacteria-substratum interactions, biofilm development and the internal microbe community. PMID:27180609

Role of Self-Directed Learning in Communication Competence and Self-Efficacy.

PubMed

Song, Youngshin; Yun, Soon Young; Kim, Sun-Ae; Ahn, Eun-Kyong; Jung, Mi Sook

2015-10-01

Although effective self-directed learning (SDL) has been shown to improve clinical performance, little is known about its role between communication competence and communication self-efficacy in nursing students. This study aimed to identify whether SDL mediates the relationship between communication competence and communication self-efficacy. A cross-sectional survey was conducted with a sample of 213 nursing students taking a basic fundamentals of nursing course. A path diagram, using structural equation modeling, was used to estimate the direct and indirect effects of communication competence on communication self-efficacy, controlling for SDL as a mediator. A structural equation model confirmed direct and indirect effects of communication competence on communication self-efficacy when SDL was controlled as a mediator. An appropriate fit to the data was identified in this mediation model of SDL. For enhancing self-efficacy regarding communication skill, the specified SDL program based on the level of communication competence will yield more effective results. Copyright 2015, SLACK Incorporated.

Multi-cellular, three-dimensional living mammalian tissue

NASA Technical Reports Server (NTRS)

Goodwin, Thomas J. (Inventor); Wolf, David A. (Inventor)

1994-01-01

The present invention relates to a multicellular, three-dimensional, living mammalian tissue. The tissue is produced by a co-culture process wherein two distinct types of mammalian cells are co-cultured in a rotating bioreactor which is completely filled with culture media and cell attachment substrates. As the size of the tissue assemblies formed on the attachment substrates changes, the rotation of the bioreactor is adjusted accordingly.

Dimethylaminoethanol affects the viability of human cultured fibroblasts.

PubMed

Gragnani, Alfredo; Giannoccaro, Fabiana Bocci; Sobral, Christiane S; Moraes, A A F; França, Jeronimo P; Ferreira, A T; Ferreira, Lydia Masako

2007-01-01

In clinical practice, dimethylaminoethanol (DMAE) has been used in the fight against wrinkles and flaccidity in the cervicofacial region. The firming action of DMAE is explained by the fact that its molecule, considered to be a precursor of acetylcholine, alters muscle contraction. However, no experimental studies have confirmed this theory. Because the actual mechanism of DMAE action was not defined and there were no references in the literature regarding its direct action on fibroblasts, this study was performed to evaluate the direct action of DMAE on cultured human fibroblasts. Human fibroblasts obtained from discarded fragments of total skin from patients undergoing plastic or reconstructive surgical procedures performed within the Plastic Surgery Division at the Federal University of São Paulo were used for this study. The explant technique was used. The culture medium was supplemented with different concentrations of DMAE on the fourth cell passage, and the cell proliferation rate, cytosolic calcium levels, and cell cycle were evaluated. Statistical analysis was performed using analysis of variance (ANOVA) followed by a Newman-Keuls test for multiple comparisons. A decrease in fibroblast proliferation was associated with an increase in DMAE concentration. A longer treatment time with trypsin was required for the groups treated with DMAE in a dose-dependent manner. In the presence of DMAE, cytosolic calcium increased in a dose-dependent manner. Apoptosis also increased in groups treated with DMAE. Dimethylaminoethanol reduced the proliferation of fibroblasts, increased cytosolic calcium, and changed the cell cycle, causing an increase in apoptosis in cultured human fibroblasts.

Structurally diverse natural products that cause potassium leakage trigger multicellularity in Bacillus subtilis.

PubMed

López, Daniel; Fischbach, Michael A; Chu, Frances; Losick, Richard; Kolter, Roberto

2009-01-06

We report a previously undescribed quorum-sensing mechanism for triggering multicellularity in Bacillus subtilis. B. subtilis forms communities of cells known as biofilms in response to an unknown signal. We discovered that biofilm formation is stimulated by a variety of small molecules produced by bacteria--including the B. subtilis nonribosomal peptide surfactin--that share the ability to induce potassium leakage. Natural products that do not cause potassium leakage failed to induce multicellularity. Small-molecule-induced multicellularity was prevented by the addition of potassium, but not sodium or lithium. Evidence is presented that potassium leakage stimulates the activity of a membrane protein kinase, KinC, which governs the expression of genes involved in biofilm formation. We propose that KinC responds to lowered intracellular potassium concentration and that this is a quorum-sensing mechanism that enables B. subtilis to respond to related and unrelated bacteria.

When do gamblers help themselves? Self-discontinuity increases self-directed change over time.

PubMed

Kim, Hyoun S; Wohl, Michael J A; Salmon, Melissa; Santesso, Diane

2017-01-01

Most disordered gamblers fail to take the necessary action to change their behavior. When action is taken, it is typically done under self-direction. Yet, little is known about what motivates gamblers to engage in self-directed change as researchers have focused almost exclusively on barriers to treatment seeking. Herein, we tested whether self-discontinuity (i.e., the notion that the self has undergone fundamental changes as a result of one's gambling) predicts self-directed change among gamblers experiencing sub-clinical levels of disordered gambling. Further, we tested whether this relationship would hold when controlling for feelings of shame and guilt about one's gambling as well as self-stigma as a disordered gambler (i.e., known barriers to change). To this end, 195 gamblers from the community completed a questionnaire battery that contained the variables of interest. Six months later, participants were re-contacted to assess whether they engaged in self-directed change. As hypothesized, the likelihood that self-directed change was attempted increased to the extent participants reported feeling self-discontinuous - an effect that remained significant when controlling for shame, guilt, and self-stigma. Results suggest that heightening the awareness that the gambling has fundamentally changed the self increases the likelihood of gamblers taking action to change their disordered gambling behaviors. Copyright © 2016. Published by Elsevier Ltd.

Growth-mediated autochemotactic pattern formation in self-propelling bacteria

NASA Astrophysics Data System (ADS)

Mukherjee, Mrinmoy; Ghosh, Pushpita

2018-01-01

Bacteria, while developing a multicellular colony or biofilm, can undergo pattern formation by diverse intricate mechanisms. One such route is directional movement or chemotaxis toward or away from self-secreted or externally employed chemicals. In some bacteria, the self-produced signaling chemicals or autoinducers themselves act as chemoattractants or chemorepellents and thereby regulate the directional movements of the cells in the colony. In addition, bacteria follow a certain growth kinetics which is integrated in the process of colony development. Here, we study the interplay of bacterial growth dynamics, cell motility, and autochemotactic motion with respect to the self-secreted diffusive signaling chemicals in spatial pattern formation. Using a continuum model of motile bacteria, we show growth can act as a crucial tuning parameter in determining the spatiotemporal dynamics of a colony. In action of growth dynamics, while chemoattraction toward autoinducers creates arrested phase separation, pattern transitions and suppression can occur for a fixed chemorepulsive strength.

Potential role of fibroblast growth factor in enhancement of fracture healing.

PubMed

Radomsky, M L; Thompson, A Y; Spiro, R C; Poser, J W

1998-10-01

Fibroblast growth factors are present in significant amounts in bone and several studies have suggested that they may be involved in normal fracture healing. It is well established that fibroblast growth factors have mitogenic and angiogenic activity on mesoderm and neuroectoderm derived cells. Of particular interest as a member of the fibroblast growth factor family, basic fibroblast growth factor stimulates mitogenesis, chemotaxis, differentiation, and angiogenesis. It also plays an important role in the development of vascular, nervous, and skeletal systems, promotes the maintenance and survival of certain tissues, and stimulates wound healing and tissue repair. Animal studies have shown that the direct injection of fibroblast growth factor into fresh fractures stimulates callus formation, which provides mechanical stability to the fracture, accelerates healing, and restores competence. The matrix used to present the fibroblast growth factor at the fracture site plays a critical role in the effectiveness of the treatment. The evaluation of injectable basic fibroblast growth factor in a sodium hyaluronate gel for its effectiveness in stimulating fracture healing is described. When applied directly into a freshly created fracture in the rabbit fibula, a single injection of the basic fibroblast growth factor and hyaluronan results in the stimulation of callus formation, increased bone formation, and earlier restoration of mechanical strength at the fracture site. The hyaluronan gel serves as a reservoir that sequesters the basic fibroblast growth factor at the injection site for the length of time necessary to create an environment conducive to fracture healing. It is concluded that basic fibroblast growth factor and sodium hyaluronate act synergistically to accelerate fracture healing and that the combination is suitable for clinical evaluation as a therapy in fracture treatment.

Fibrogenic Lung Injury Induces Non-Cell-Autonomous Fibroblast Invasion.

PubMed

Ahluwalia, Neil; Grasberger, Paula E; Mugo, Brian M; Feghali-Bostwick, Carol; Pardo, Annie; Selman, Moisés; Lagares, David; Tager, Andrew M

2016-06-01

Pathologic accumulation of fibroblasts in pulmonary fibrosis appears to depend on their invasion through basement membranes and extracellular matrices. Fibroblasts from the fibrotic lungs of patients with idiopathic pulmonary fibrosis (IPF) have been demonstrated to acquire a phenotype characterized by increased cell-autonomous invasion. Here, we investigated whether fibroblast invasion is further stimulated by soluble mediators induced by lung injury. We found that bronchoalveolar lavage fluids from bleomycin-challenged mice or patients with IPF contain mediators that dramatically increase the matrix invasion of primary lung fibroblasts. Further characterization of this non-cell-autonomous fibroblast invasion suggested that the mediators driving this process are produced locally after lung injury and are preferentially produced by fibrogenic (e.g., bleomycin-induced) rather than nonfibrogenic (e.g., LPS-induced) lung injury. Comparison of invasion and migration induced by a series of fibroblast-active mediators indicated that these two forms of fibroblast movement are directed by distinct sets of stimuli. Finally, knockdown of multiple different membrane receptors, including platelet-derived growth factor receptor-β, lysophosphatidic acid 1, epidermal growth factor receptor, and fibroblast growth factor receptor 2, mitigated the non-cell-autonomous fibroblast invasion induced by bronchoalveolar lavage from bleomycin-injured mice, suggesting that multiple different mediators drive fibroblast invasion in pulmonary fibrosis. The magnitude of this mediator-driven fibroblast invasion suggests that its inhibition could be a novel therapeutic strategy for pulmonary fibrosis. Further elaboration of the molecular mechanisms that drive non-cell-autonomous fibroblast invasion consequently may provide a rich set of novel drug targets for the treatment of IPF and other fibrotic lung diseases.

MicroRNA-124 Controls the Proliferative, Migratory, and Inflammatory Phenotype of Pulmonary Vascular Fibroblasts

PubMed Central

Wang, Daren; Zhang, Zhang; Li, Min; Frid, Maria G.; Flockton, Amanda R.; McKeon, B. Alexandre; Yeager, Michael E.; Fini, Mehdi A.; Morrell, Nicholas W.; Pullamsetti, Soni S.; Velegala, Sivareddy; Seeger, Werner; McKinsey, Timothy A.; Sucharov, Carmen C.; Stenmark, Kurt R.

2014-01-01

Rationale Pulmonary hypertensive remodeling is characterized by excessive proliferation, migration, and proinflammatory activation of adventitial fibroblasts. In culture, fibroblasts maintain a similar activated phenotype. The mechanisms responsible for generation/maintenance of this phenotype remain unknown. Objective We hypothesized that aberrant expression of microRNA-124 (miR-124) regulates this activated fibroblast phenotype and sought to determine the signaling pathways through which miR-124 exerts effects. Methods and Results We detected significant decreases in miR-124 expression in fibroblasts isolated from calves and humans with severe pulmonary hypertension. Overexpression of miR-124 by mimic transfection significantly attenuated proliferation, migration, and monocyte chemotactic protein-1 expression of hypertensive fibroblasts, whereas anti–miR-124 treatment of control fibroblasts resulted in their increased proliferation, migration, and monocyte chemotactic protein-1 expression. Furthermore, the alternative splicing factor, polypyrimidine tract–binding protein 1, was shown to be a direct target of miR-124 and to be upregulated both in vivo and in vitro in bovine and human pulmonary hypertensive fibroblasts. The effects of miR-124 on fibroblast proliferation were mediated via direct binding to the 3′ untranslated region of polypyrimidine tract–binding protein 1 and subsequent regulation of Notch1/phosphatase and tensin homolog/FOXO3/p21Cip1 and p27Kip1 signaling. We showed that miR-124 directly regulates monocyte chemotactic protein-1 expression in pulmonary hypertension/idiopathic pulmonary arterial hypertension fibroblasts. Furthermore, we demonstrated that miR-124 expression is suppressed by histone deacetylases and that treatment of hypertensive fibroblasts with histone deacetylase inhibitors increased miR-124 expression and decreased proliferation and monocyte chemotactic protein-1 production. Conclusions Stable decreases in miR-124

Processing and characterization of multi-cellular monolithic bioceramics for bone regenerative scaffolds

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

Ari-Wahjoedi, Bambang, E-mail: bambang-ariwahjoedi@petronas.com.my; Centre for Intelligent Signal and Imaging Research, Universiti Teknologi PETRONAS, Bandar Seri Iskandar; Ginta, Turnad Lenggo

2014-10-24

Multicellular monolithic ceramic body is a ceramic material which has many gas or liquid passages partitioned by thin walls throughout the bulk material. There are many currently known advanced industrial applications of multicellular ceramics structures i.e. as supports for various catalysts, electrode support structure for solid oxide fuel cells, refractories, electric/electronic materials, aerospace vehicle re-entry heat shields and biomaterials for dental as well as orthopaedic implants by naming only a few. Multicellular ceramic bodies are usually made of ceramic phases such as mullite, cordierite, aluminum titanate or pure oxides such as silica, zirconia and alumina. What make alumina ceramics ismore » excellent for the above functions are the intrinsic properties of alumina which are hard, wear resistant, excellent dielectric properties, resists strong acid and alkali attacks at elevated temperatures, good thermal conductivities, high strength and stiffness as well as biocompatible. In this work the processing technology leading to truly multicellular monolithic alumina ceramic bodies and their characterization are reported. Ceramic slip with 66 wt.% solid loading was found to be optimum as impregnant to the polyurethane foam template. Mullitic ceramic composite of alumina-sodium alumino disilicate-Leucite-like phases with bulk and true densities of 0.852 and 1.241 g cm{sup −3} respectively, pore linear density of ±35 cm{sup −1}, linear and bulk volume shrinkages of 7-16% and 32 vol.% were obtained. The compressive strength and elastic modulus of the bioceramics are ≈0.5-1.0 and ≈20 MPa respectively.« less

Neurons generated by direct conversion of fibroblasts reproduce synaptic phenotype caused by autism-associated neuroligin-3 mutation.

PubMed

Chanda, Soham; Marro, Samuele; Wernig, Marius; Südhof, Thomas C

2013-10-08

Recent studies suggest that induced neuronal (iN) cells that are directly transdifferentiated from nonneuronal cells provide a powerful opportunity to examine neuropsychiatric diseases. However, the validity of using this approach to examine disease-specific changes has not been demonstrated. Here, we analyze the phenotypes of iN cells that were derived from murine embryonic fibroblasts cultured from littermate wild-type and mutant mice carrying the autism-associated R704C substitution in neuroligin-3. We show that neuroligin-3 R704C-mutant iN cells exhibit a large and selective decrease in AMPA-type glutamate receptor-mediated synaptic transmission without changes in NMDA-type glutamate receptor- or in GABAA receptor-mediated synaptic transmission. Thus, the synaptic phenotype observed in R704C-mutant iN cells replicates the previously observed phenotype of R704C-mutant neurons. Our data show that the effect of the R704C mutation is applicable even to neurons transdifferentiated from fibroblasts and constitute a proof-of-concept demonstration that iN cells can be used for cellular disease modeling.

Neurons generated by direct conversion of fibroblasts reproduce synaptic phenotype caused by autism-associated neuroligin-3 mutation

PubMed Central

Chanda, Soham; Marro, Samuele; Wernig, Marius; Südhof, Thomas C.

2013-01-01

Recent studies suggest that induced neuronal (iN) cells that are directly transdifferentiated from nonneuronal cells provide a powerful opportunity to examine neuropsychiatric diseases. However, the validity of using this approach to examine disease-specific changes has not been demonstrated. Here, we analyze the phenotypes of iN cells that were derived from murine embryonic fibroblasts cultured from littermate wild-type and mutant mice carrying the autism-associated R704C substitution in neuroligin-3. We show that neuroligin-3 R704C-mutant iN cells exhibit a large and selective decrease in AMPA-type glutamate receptor-mediated synaptic transmission without changes in NMDA-type glutamate receptor- or in GABAA receptor-mediated synaptic transmission. Thus, the synaptic phenotype observed in R704C-mutant iN cells replicates the previously observed phenotype of R704C-mutant neurons. Our data show that the effect of the R704C mutation is applicable even to neurons transdifferentiated from fibroblasts and constitute a proof-of-concept demonstration that iN cells can be used for cellular disease modeling. PMID:24046374

Glycogen-nucleic acid constructs for gene silencing in multicellular tumor spheroids.

PubMed

Wojnilowicz, Marcin; Besford, Quinn A; Wu, Yun-Long; Loh, Xian Jun; Braunger, Julia A; Glab, Agata; Cortez-Jugo, Christina; Caruso, Frank; Cavalieri, Francesca

2018-05-20

The poor penetration of nanocarrier-siRNA constructs into tumor tissue is a major hurdle for the in vivo efficacy of siRNA therapeutics, where the ability of the constructs to permeate the 3D multicellular matrix is determined by their physicochemical properties. Herein, we optimized the use of soft glycogen nanoparticles for the engineering of glycogen-siRNA constructs that can efficiently penetrate multicellular tumor spheroids and exert a significant gene silencing effect. Glycogen nanoparticles from different bio-sources and with different structural features were investigated. We show that larger glycogen nanoparticles ranging from 50 to 80 nm are suboptimal systems for complexation of nucleic acids if fine control of the size of constructs is required. Our studies suggest that 20 nm glycogen nanoparticles are optimal for complexation and efficient delivery of siRNA. The chemical composition, surface charge, and size of glycogen-siRNA constructs were finely controlled to minimize interactions with serum proteins and allow penetration into 3D multicellular spheroids of human kidney epithelial cells and human prostate cancer cells. We introduced pH sensitive moieties within the construct to enhance early endosome escape and efficiently improve the silencing effect in vitro. Glycogen-siRNA constructs were found to mediate gene silencing in 3D multicellular spheroids causing ∼60% specific gene silencing. The optimized construct exhibited an in vivo circulation lifetime of 8 h in mice, with preferential accumulation in the liver. No accumulation in the kidney, lung, spleen, heart or brain, or signs of toxicity in mice were observed. Our results highlight the potential for screening siRNA nanocarriers in 3D cultured prostate tumor models, thereby improving the predictive therapeutic efficacy of glycogen-based platforms in human physiological conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Effects of direct current electric field on directional migration and arrangement of dermal fibroblasts in neonatal BALB/c mice and the mechanisms].

PubMed

Liu, Jie; Ren, Xi; Guo, Xiaowei; Sun, Huanbo; Tang, Yong; Luo, Zhenghui; Zhang, Qiong; Zhang, Dongxia; Huang, Yuesheng; Zhang, Jiaping

2016-04-01

To explore the effects of direct current electric fields on directional migration and arrangement of dermal fibroblasts in neonatal BALB/c mice and the related mechanisms. Twelve neonatal BALB/c mice were divided into 4 batches. The skin on the back of 3 neonatal mice in each batch was obtained to culture fibroblasts. Fibroblasts of the second passage were inoculated in 27 square cover slips with the concentration of 5 × 10(4) cells per mL. (1) Experiment 1. Six square cover slips inoculated with fibroblasts of the second passage were divided into electric field group (EF) and sham electric field group (SEF), with 3 cover slips in each group. The cover slips were put in live cell imaging workstation. The cells in group EF was treated with electric power with EF intensity of 200 mV/mm, while simulating process without actual power was given to SEF group (the same below) for 6 h. Cell proliferation rate was subsequently counted. (2) Experiment 2. Six cover slips were divided and underwent the same processes as in experiment 1. Cell movement locus within EF hour (EFH) 6, direction change of cell migration at EFH 0 (immediately), 1, 2, 3, 4, 5, and 6 which was denoted as cos(α), cell migration velocity within EFH 6, direction change of long axis of cell within EFH 6, and direction change of cell arrangement at EFH 0, 1, 2, 3, 4, 5, and 6 which was denoted as polarity value cos[2(θ-90)] were observed under live cell imaging workstation. After EFH 6, the morphological changes in microtubules and microfilaments were observed with immunofluorescent staining. (3) Experiment 3. Six cover slips were divided into cytochalasin D group (treated with 1 μmol/L cytochalasin D for 10 min) and colchicine group (treated with 5 μmol/L colchicine for 10 min), with 3 cover slips in each group. The morphological changes in microfilaments and microtubules were observed with the same method as in experiment 2. (4) Experiment 4. Nine cover slips were divided into control group (no

Harmonizing Self-Directed and Teacher-Directed Approaches to Learning.

ERIC Educational Resources Information Center

Bell, Deanne F.; Bell, Durward L.

1983-01-01

A combination of self-directed learning and teacher-directed learning provides a rich and flexible learning experience and accommodates various teaching styles. The key to a successful mixture is the appropriate use of criterion-referencing and normative-referencing for learner evaluation. (JOW)

Activation of cardiac fibroblasts by ethanol is blocked by TGF-β inhibition

PubMed Central

Law, Brittany A.; Carver, Wayne E.

2013-01-01

Background Alcohol abuse is the second leading cause of dilated cardiomyopathy, a disorder specifically referred to as Alcoholic Cardiomyopathy (ACM). Rodent and human studies have revealed cardiac fibrosis to be a consequence of ACM and prior studies by this lab have associated this occurrence with elevated transforming growth factor-beta (TGF-β) and activated fibroblasts (myofibroblasts). To date there have been no other studies to investigate the direct effect of alcohol on the cardiac fibroblast. Methods Primary rat cardiac fibroblasts were cultured in the presence of ethanol and assayed for fibroblast activation by collagen gel contraction, alpha smooth muscle- actin (α-SMA) expression, migration, proliferation, apoptosis, collagen I & III and TGF-β expression. The TGF-β receptor type 1 inhibitor compound SB 431542 and a soluble recombinant TGF-βII receptor (RbII) were used to assess the role of of TGF-β in the response of cardiac fibroblasts to ethanol. Results Treatment of cardiac fibroblasts with ethanol at concentrations of 100 mg/dl or higher resulted in fibroblast activation and fibrogenic activity after 24 hours including an increase in contraction, α-SMA expression, migration, and expression of collagen I and TGF-β. No changes in fibroblast proliferation or apoptosis were observed. Inhibition of TGF-β by SB 431542 and RbII attenuated the ethanol-induced fibroblast activation. Conclusions Ethanol treatment directly promotes cardiac fibroblast activation by stimulating TGF-β release from fibroblasts. Inhibiting the action of TGF-β decreases the fibrogenic effect induced by ethanol treatment. The results of this study support TGF-β to be an important component in cardiac fibrosis induced by exposure to ethanol. PMID:23528014

Self-directed work teams in marketing organizations.

PubMed

Gilbertson, T F

1999-01-01

As marketing organizations move toward the 21st century they are becoming concerned with the development of self-directed work teams. Marketing organizations that have informed, motivated, skilled, trained, and committed employees will out perform organizations which operate in the traditional manner. Many self-directed work teams have grown out of the quality circles. The goal of these teams is to increase employee involvement in decisions of the organization to the greatest extent that employees' knowledge and training allow. In fact, today's marketing organizations need to be able to respond quickly to change driven by internal and external customers. The winning organizations will be able to produce more product with better quality in less time by staying lean, flexible, and implementing self-directed work teams. Marketing organizations that can commit to self-directed work teams will benefit by having customer and employee satisfaction, money saved, and excessive bureaucracy eliminated.

Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics.

PubMed

Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

2016-02-04

Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level.

Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics

PubMed Central

Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

2016-01-01

Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level. PMID:26841954

Bioelectrical Signals and Ion Channels in the Modeling of Multicellular Patterns and Cancer Biophysics

NASA Astrophysics Data System (ADS)

Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

2016-02-01

Bioelectrical signals and ion channels are central to spatial patterns in cell ensembles, a problem of fundamental interest in positional information and cancer processes. We propose a model for electrically connected cells based on simple biological concepts: i) the membrane potential of a single cell characterizes its electrical state; ii) the long-range electrical coupling of the multicellular ensemble is realized by a network of gap junction channels between neighboring cells; and iii) the spatial distribution of an external biochemical agent can modify the conductances of the ion channels in a cell membrane and the multicellular electrical state. We focus on electrical effects in small multicellular ensembles, ignoring slow diffusional processes. The spatio-temporal patterns obtained for the local map of cell electric potentials illustrate the normalization of regions with abnormal cell electrical states. The effects of intercellular coupling and blocking of specific channels on the electrical patterns are described. These patterns can regulate the electrically-induced redistribution of charged nanoparticles over small regions of a model tissue. The inclusion of bioelectrical signals provides new insights for the modeling of cancer biophysics because collective multicellular states show electrical coupling mechanisms that are not readily deduced from biochemical descriptions at the individual cell level.

Fibroblast-matrix interplay: Nintedanib and pirfenidone modulate the effect of IPF fibroblast-conditioned matrix on normal fibroblast phenotype.

PubMed

Epstein Shochet, Gali; Wollin, Lutz; Shitrit, David

2018-03-12

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with poor prognosis. Activated fibroblasts are the key effector cells in fibrosis, producing excessive amounts of collagen and extracellular matrix (ECM) proteins. Whether the ECM conditioned by IPF fibroblasts determines the phenotype of naïve fibroblasts is difficult to explore. IPF-derived primary fibroblasts were cultured on Matrigel and then cleared using ammonium hydroxide, creating an IPF-conditioned matrix (CM). Normal fibroblast CM served as control. Normal fibroblasts were cultured on both types of CM, and cell count, cell distribution and markers of myofibroblast differentiation; transforming growth factor beta (TGFβ) signalling; and ECM expression were assessed. The effects of the anti-fibrotic drugs nintedanib and pirfenidone at physiologically relevant concentrations were also explored. Normal fibroblasts cultured on IPF-CM arranged in large aggregates as a result of increased proliferation and migration. Moreover, increased levels of pSmad3, pSTAT3 (phospho signal transducer and activator of transcription 3), alpha smooth muscle actin (αSMA) and Collagen1a were found, suggesting a differentiation towards a myofibroblast-like phenotype. SB505124 (10 μmol/L) partially reversed these alterations, suggesting a TGFβ contribution. Furthermore, nintedanib at 100 nmol/L and, to a lesser extent, pirfenidone at 100 μmol/L prevented the IPF-CM-induced fibroblast phenotype alterations, suggesting an attenuation of the ECM-fibroblast interplay. IPF fibroblasts alter the ECM, thus creating a CM that further propagates an IPF-like phenotype in normal fibroblasts. This assay demonstrated differences in drug activities for approved IPF drugs at clinically relevant concentrations. Thus, the matrix-fibroblast phenotype interplay might be a relevant assay to explore drug candidates for IPF treatment. © 2018 Asian Pacific Society of Respirology.

Mesenchymal stem cells induce dermal fibroblast responses to injury

PubMed Central

Smith, Andria N.; Willis, Elise; Chan, Vincent T.; Muffley, Lara A.; Isik, F. Frank; Gibran, Nicole S.; Hocking, Anne M.

2009-01-01

Although bone marrow-derived mesenchymal stem cells have been shown to promote repair when applied to cutaneous wounds, the mechanism for this response remains to be determined. The aim of this study was to determine the effects of paracrine signaling from mesenchymal stem cells on dermal fibroblast responses to injury including proliferation, migration and expression of genes important in wound repair. Dermal fibroblasts were co-cultured with bone marrow-derived mesenchymal stem cells grown in inserts, which allowed for paracrine interactions without direct cell contact. In this co-culture model, bone marrow-derived mesenchymal stem cells regulate dermal fibroblast proliferation, migration and gene expression. When co-cultured with mesenchymal stem cells, dermal fibroblasts show increased proliferation and accelerated migration in a scratch assay. A chemotaxis assay also demonstrated that dermal fibroblasts migrate towards bone marrow-derived mesenchymal stem cells. A PCR array was used to analyze the effect of mesenchymal stem cells on dermal fibroblast gene expression. In response to mesenchymal stem cells, dermal fibroblasts up-regulate integrin alpha 7 expression and down-regulate expression of ICAM1, VCAM1 and MMP11. These observations suggest that mesenchymal stem cells may provide an important early signal for dermal fibroblast responses to cutaneous injury. PMID:19666021

Mesenchymal stem cells induce dermal fibroblast responses to injury

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

Smith, Andria N., E-mail: snosmith@u.washington.edu; Willis, Elise, E-mail: elise.willis@gmail.com; Chan, Vincent T.

2010-01-01

Although bone marrow-derived mesenchymal stem cells have been shown to promote repair when applied to cutaneous wounds, the mechanism for this response remains to be determined. The aim of this study was to determine the effects of paracrine signaling from mesenchymal stem cells on dermal fibroblast responses to injury including proliferation, migration and expression of genes important in wound repair. Dermal fibroblasts were co-cultured with bone marrow-derived mesenchymal stem cells grown in inserts, which allowed for paracrine interactions without direct cell contact. In this co-culture model, bone marrow-derived mesenchymal stem cells regulate dermal fibroblast proliferation, migration and gene expression. Whenmore » co-cultured with mesenchymal stem cells, dermal fibroblasts show increased proliferation and accelerated migration in a scratch assay. A chemotaxis assay also demonstrated that dermal fibroblasts migrate towards bone marrow-derived mesenchymal stem cells. A PCR array was used to analyze the effect of mesenchymal stem cells on dermal fibroblast gene expression. In response to mesenchymal stem cells, dermal fibroblasts up-regulate integrin alpha 7 expression and down-regulate expression of ICAM1, VCAM1 and MMP11. These observations suggest that mesenchymal stem cells may provide an important early signal for dermal fibroblast responses to cutaneous injury.« less

Development and Application of Functionalized Protein Binders in Multicellular Organisms.

PubMed

Bieli, D; Alborelli, I; Harmansa, S; Matsuda, S; Caussinus, E; Affolter, M

2016-01-01

Protein-protein interactions are crucial for almost all biological processes. Studying such interactions in their native environment is critical but not easy to perform. Recently developed genetically encoded protein binders were shown to function inside living cells. These molecules offer a new, direct way to assess protein function, distribution and dynamics in vivo. A widely used protein binder scaffold are the so-called nanobodies, which are derived from the variable domain of camelid heavy-chain antibodies. Another commonly used scaffold, the DARPins, is based on Ankyrin repeats. In this review, we highlight how these binders can be functionalized in order to study proteins in vivo during the development of multicellular organisms. It is to be anticipated that many more applications for such synthetic protein binders will be developed in the near future. Copyright © 2016 Elsevier Inc. All rights reserved.

Ethanol Inactivated Mouse Embryonic Fibroblasts Maintain the Self-Renew and Proliferation of Human Embryonic Stem Cells.

PubMed

Huang, Boxian; Ning, Song; Zhuang, Lili; Jiang, Chunyan; Cui, Yugui; Fan, Guoping; Qin, Lianju; Liu, Jiayin

2015-01-01

Conventionally, mouse embryonic fibroblasts (MEFs) inactivated by mitomycin C or irradiation were applied to support the self-renew and proliferation of human embryonic stem cells (hESCs). To avoid the disadvangtages of mitomycin C and irradiation, here MEFs were treated by ethanol (ET). Our data showed that 10% ET-inactivated MEFs (eiMEFs) could well maintain the self-renew and proliferation of hESCs. hESCs grown on eiMEFs expressed stem cell markers of NANOG, octamer-binding protein 4 (OCT4), stage-specific embryonic antigen-4 (SSEA4) and tumour related antigen-1-81 (TRA-1-81), meanwhile maintained normal karyotype after long time culture. Also, hESCs cocultured with eiMEFs were able to form embryoid body (EB) in vitro and develop teratoma in vivo. Moreover, eiMEFs could keep their nutrient functions after long time cryopreservation. Our results indicate that the application of eiMEF in hESCs culture is safe, economical and convenient, thus is a better choice.

Life cycles, fitness decoupling and the evolution of multicellularity.

PubMed

Hammerschmidt, Katrin; Rose, Caroline J; Kerr, Benjamin; Rainey, Paul B

2014-11-06

Cooperation is central to the emergence of multicellular life; however, the means by which the earliest collectives (groups of cells) maintained integrity in the face of destructive cheating types is unclear. One idea posits cheats as a primitive germ line in a life cycle that facilitates collective reproduction. Here we describe an experiment in which simple cooperating lineages of bacteria were propagated under a selective regime that rewarded collective-level persistence. Collectives reproduced via life cycles that either embraced, or purged, cheating types. When embraced, the life cycle alternated between phenotypic states. Selection fostered inception of a developmental switch that underpinned the emergence of collectives whose fitness, during the course of evolution, became decoupled from the fitness of constituent cells. Such development and decoupling did not occur when groups reproduced via a cheat-purging regime. Our findings capture key events in the evolution of Darwinian individuality during the transition from single cells to multicellularity.

Allometry and stoichiometry of unicellular, colonial and multicellular phytoplankton.

PubMed

Beardall, John; Allen, Drew; Bragg, Jason; Finkel, Zoe V; Flynn, Kevin J; Quigg, Antonietta; Rees, T Alwyn V; Richardson, Anthony; Raven, John A

2009-01-01

Phytoplankton life forms, including unicells, colonies, pseudocolonies, and multicellular organisms, span a huge size range. The smallest unicells are less than 1 microm3 (e.g. cyanobacteria), while large unicellular diatoms may attain 10(9) microm3, being visible to the naked eye. Phytoplankton includes chemo-organotrophic unicells, colonies and multicellular organisms that depend on symbionts or kleptoplastids for their capacity to photosynthesize. Analyses of physical (transport within cells, diffusion boundary layers, package effect, turgor, and vertical movements) and biotic (grazing, viruses and other parasitoids) factors indicate potential ecological constraints and opportunities that differ among the life forms. There are also variations among life forms in elemental stoichiometry and in allometric relations between biovolume and specific growth. While many of these factors probably have ecological and evolutionary significance, work is needed to establish those that are most important, warranting explicit description in models. Other factors setting limitations on growth rate (selecting slow-growing species) await elucidation.

Silibinin prevents prostate cancer cell-mediated differentiation of naïve fibroblasts into cancer-associated fibroblast phenotype by targeting TGF β2.

PubMed

Ting, Harold J; Deep, Gagan; Jain, Anil K; Cimic, Adela; Sirintrapun, Joseph; Romero, Lina M; Cramer, Scott D; Agarwal, Chapla; Agarwal, Rajesh

2015-09-01

Tumor microenvironment (TM) is an essential element in prostate cancer (PCA), offering unique opportunities for its prevention. TM includes naïve fibroblasts that are recruited by nascent neoplastic lesion and altered into 'cancer-associated fibroblasts' (CAFs) that promote PCA. A better understanding and targeting of interaction between PCA cells and fibroblasts and inhibiting CAF phenotype through non-toxic agents are novel approaches to prevent PCA progression. One well-studied cancer chemopreventive agent is silibinin, and thus, we examined its efficacy against PCA cells-mediated differentiation of naïve fibroblasts into a myofibroblastic-phenotype similar to that found in CAFs. Silibinin's direct inhibitory effect on the phenotype of CAFs derived directly from PCA patients was also assessed. Human prostate stromal cells (PrSCs) exposed to control conditioned media (CCM) from human PCA PC3 cells showed more invasiveness, with increased alpha-smooth muscle actin (α-SMA) and vimentin expression, and differentiation into a phenotype we identified in CAFs. Importantly, silibinin (at physiologically achievable concentrations) inhibited α-SMA expression and invasiveness in differentiated fibroblasts and prostate CAFs directly, as well as indirectly by targeting PCA cells. The observed increase in α-SMA and CAF-like phenotype was transforming growth factor (TGF) β2 dependent, which was strongly inhibited by silibinin. Furthermore, induction of α-SMA and CAF phenotype by CCM were also strongly inhibited by a TGFβ2-neutralizing antibody. The inhibitory effect of silibinin on TGFβ2 expression and CAF-like biomarkers was also observed in PC3 tumors. Together, these findings highlight the potential usefulness of silibinin in PCA prevention through targeting the CAF phenotype in the prostate TM. © 2014 Wiley Periodicals, Inc.

Real-time viability and apoptosis kinetic detection method of 3D multicellular tumor spheroids using the Celigo Image Cytometer.

PubMed

Kessel, Sarah; Cribbes, Scott; Bonasu, Surekha; Rice, William; Qiu, Jean; Chan, Leo Li-Ying

2017-09-01

The development of three-dimensional (3D) multicellular tumor spheroid models for cancer drug discovery research has increased in the recent years. The use of 3D tumor spheroid models may be more representative of the complex in vivo tumor microenvironments in comparison to two-dimensional (2D) assays. Currently, viability of 3D multicellular tumor spheroids has been commonly measured on standard plate-readers using metabolic reagents such as CellTiter-Glo® for end point analysis. Alternatively, high content image cytometers have been used to measure drug effects on spheroid size and viability. Previously, we have demonstrated a novel end point drug screening method for 3D multicellular tumor spheroids using the Celigo Image Cytometer. To better characterize the cancer drug effects, it is important to also measure the kinetic cytotoxic and apoptotic effects on 3D multicellular tumor spheroids. In this work, we demonstrate the use of PI and caspase 3/7 stains to measure viability and apoptosis for 3D multicellular tumor spheroids in real-time. The method was first validated by staining different types of tumor spheroids with PI and caspase 3/7 and monitoring the fluorescent intensities for 16 and 21 days. Next, PI-stained and nonstained control tumor spheroids were digested into single cell suspension to directly measure viability in a 2D assay to determine the potential toxicity of PI. Finally, extensive data analysis was performed on correlating the time-dependent PI and caspase 3/7 fluorescent intensities to the spheroid size and necrotic core formation to determine an optimal starting time point for cancer drug testing. The ability to measure real-time viability and apoptosis is highly important for developing a proper 3D model for screening tumor spheroids, which can allow researchers to determine time-dependent drug effects that usually are not captured by end point assays. This would improve the current tumor spheroid analysis method to potentially better

Genetic polymorphism directs IL-6 expression in fibroblasts but not selected other cell types

PubMed Central

Noss, Erika H.; Nguyen, Hung N.; Chang, Sook Kyung; Watts, Gerald F. M.; Brenner, Michael B.

2015-01-01

Interleukin (IL)-6 blockade is an effective treatment for rheumatoid arthritis (RA), and synovial fibroblasts are a major IL-6 producer in the inflamed joint. We found that human RA and osteoarthritis (OA) synovial fibroblasts derived from independent donors reproducibly segregated into low, medium, and high IL-6 producers, independent of stimulus, cell passage, or disease state. IL-6 expression pattern correlated strongly with total mRNA expression, not mRNA stability, suggesting transcriptional rather than posttranscriptional regulation. High-fibroblast IL-6 expression was significantly associated with the IL-6 proximal promoter single nucleotide polymorphism (SNP) rs1800795 minor allele (CC) genotype. In contrast, no association between this SNP and IL-6 production was detected in CD14+ monocytes, another major producer of synovial IL-6. Luciferase expression assays confirmed that this SNP was associated with differential IL-6 expression in fibroblasts. To date, several association studies examining rs1800795 allele frequency and disease risk have reported seemingly conflicting results ranging from no association to association with either the major or minor allele across a spectrum of conditions, including cancer and autoimmune, cardiovascular, infectious, and metabolic diseases. This study points to a prominent contribution from promoter genetic variation in fibroblast IL-6 regulation, but not in other IL-6–producing cell types. We propose that some of the heterogeneity in these clinical studies likely reflects the cellular source of IL-6 in specific diseases, much of which may be produced by nonhematopoietic cells. These results highlight that functional analysis of disease-associated SNPs on gene expression and pathologic processes must consider variation in diverse cell types. PMID:26578807

Conformation Change in a Self-recognizing Autotransporter Modulates Bacterial Cell-Cell Interaction*

PubMed Central

Girard, Victoria; Côté, Jean-Philippe; Charbonneau, Marie-Ève; Campos, Manuel; Berthiaume, Frédéric; Hancock, Mark A.; Siddiqui, Nadeem; Mourez, Michael

2010-01-01

Bacteria mostly live as multicellular communities, although they are unicellular organisms, yet the mechanisms that tie individual bacteria together are often poorly understood. The adhesin involved in diffuse adherence (AIDA-I) is an adhesin of diarrheagenic Escherichia coli strains. AIDA-I also mediates bacterial auto-aggregation and biofilm formation and thus could be important for the organization of communities of pathogens. Using purified protein and whole bacteria, we provide direct evidence that AIDA-I promotes auto-aggregation by interacting with itself. Using various biophysical and biochemical techniques, we observed a conformational change in the protein during AIDA-AIDA interactions, strengthening the notion that this is a highly specific interaction. The self-association of AIDA-I is of high affinity but can be modulated by sodium chloride. We observe that a bile salt, sodium deoxycholate, also prevents AIDA-I oligomerization and bacterial auto-aggregation. Thus, we propose that AIDA-I, and most likely other similar autotransporters such as antigen 43 (Ag43) and TibA, organize bacterial communities of pathogens through a self-recognition mechanism that is sensitive to the environment. This could permit bacteria to switch between multicellular and unicellular lifestyles to complete their infection. PMID:20123991

Activation of cardiac fibroblasts by ethanol is blocked by TGF-β inhibition.

PubMed

Law, Brittany A; Carver, Wayne E

2013-08-01

Alcohol abuse is the second leading cause of dilated cardiomyopathy, a disorder specifically referred to as alcoholic cardiomyopathy (ACM). Rodent and human studies have revealed cardiac fibrosis to be a consequence of ACM, and prior studies by this laboratory have associated this occurrence with elevated transforming growth factor-beta (TGF-β) and activated fibroblasts (myofibroblasts). To date, there have been no other studies to investigate the direct effect of alcohol on the cardiac fibroblast. Primary rat cardiac fibroblasts were cultured in the presence of ethanol (EtOH) and assayed for fibroblast activation by collagen gel contraction, alpha-smooth muscle actin (α-SMA) expression, migration, proliferation, apoptosis, collagen I and III, and TGF-β expression. The TGF-β receptor type 1 inhibitor compound SB 431542 and a soluble recombinant TGF-βII receptor (RbII) were used to assess the role of TGF-β in the response of cardiac fibroblasts to EtOH. Treatment for cardiac fibroblasts with EtOH at concentrations of 100 mg/dl or higher resulted in fibroblast activation and fibrogenic activity after 24 hours including an increase in contraction, α-SMA expression, migration, and expression of collagen I and TGF-β. No changes in fibroblast proliferation or apoptosis were observed. Inhibition of TGF-β by SB 431542 and RbII attenuated the EtOH-induced fibroblast activation. EtOH treatment directly promotes cardiac fibroblast activation by stimulating TGF-β release from fibroblasts. Inhibiting the action of TGF-β decreases the fibrogenic effect induced by EtOH treatment. The results of this study support TGF-β to be an important component in cardiac fibrosis induced by exposure to EtOH. Copyright © 2013 by the Research Society on Alcoholism.

Housing and Employment Outcomes for Mental Health Self-Direction Participants.

PubMed

Croft, Bevin; İsvan, Nilüfer; Parish, Susan L; Mahoney, Kevin J

2018-05-15

In self-direction, participants control individual budgets, allocating service dollars according to needs and preferences within program parameters to meet self-defined recovery goals. Mental health self-direction is associated with enhanced wellness and recovery outcomes at lower or similar cost than traditional service arrangements. This study compared outcomes of housing independence and employment between individuals who participated in self-direction and those who did not. This quasi-experimental study involved administrative data from 271 self-directing participants. Using coarsened exact matching with observed demographic, diagnostic, and other characteristics, the authors constructed a comparison group of non-self-directing individuals (N=1,099). The likelihood of achieving positive outcomes between first and last assessments during the approximately four-year study period was compared for self-directing and non-self-directing individuals. Self-directing participants were more likely than nonparticipants to increase days worked for pay or maintain days worked at 20 or more days in the past 30 days (number needed to treat [NNT]=18; small effect size) and maintain or attain independent housing (NNT=16; small effect size), when analyses controlled, to the extent possible, for observed individual characteristics. Based on data from the nation's largest and longest-standing program of its kind, results suggest that mental health self-direction is associated with modest improvements or maintenance of positive outcomes in employment and housing independence. This research adds to the literature examining self-direction in the context of mental health and begins to fill the need for a greater understanding of self-direction's relationship to outcomes of interest to service users and families, providers, and system administrators.

Self-directed versus traditional classroom training for neonatal resuscitation.

PubMed

Weiner, Gary M; Menghini, Karin; Zaichkin, Jeanette; Caid, Ann E; Jacoby, Carrie J; Simon, Wendy M

2011-04-01

Neonatal Resuscitation Program instructors spend most of their classroom time giving lectures and demonstrating basic skills. We hypothesized that a self-directed education program could shift acquisition of these skills outside the classroom, shorten the duration of the class, and allow instructors to use their time to facilitate low-fidelity simulation and debriefing. Novice providers were randomly allocated to self-directed education or a traditional class. Self-directed participants received a textbook, instructional video, and portable equipment kit and attended a 90-minute simulation session with an instructor. The traditional class included 6 hours of lectures and instructor-directed skill stations. Outcome measures included resuscitation skill (megacode assessment score), content knowledge, participant satisfaction, and self-confidence. Forty-six subjects completed the study. There was no significant difference between the study groups in either the megacode assessment score (23.8 [traditional] vs 24.5 [self-directed]; P = .46) or fraction that passed the "megacode" (final skills assessment) (56% [traditional] vs 65% [self-directed]; P = .76). There were no significant differences in content knowledge, course satisfaction, or postcourse self-confidence. Content knowledge, years of experience, and self-confidence did not predict resuscitation skill. Self-directed education improves the educational efficiency of the neonatal resuscitation course by shifting the acquisition of cognitive and basic procedural skills outside of the classroom, which allows the instructor to add low-fidelity simulation and debriefing while significantly decreasing the duration of the course.

The multicellular nature of filamentous heterocyst-forming cyanobacteria.

PubMed

Herrero, Antonia; Stavans, Joel; Flores, Enrique

2016-11-01

Cyanobacteria carry out oxygenic photosynthesis, play a key role in the cycling of carbon and nitrogen in the biosphere, and have had a large impact on the evolution of life and the Earth itself. Many cyanobacterial strains exhibit a multicellular lifestyle, growing as filaments that can be hundreds of cells long and endowed with intercellular communication. Furthermore, under depletion of combined nitrogen, filament growth requires the activity of two interdependent cell types: vegetative cells that fix CO2 and heterocysts that fix N2. Intercellular molecular transfer is essential for signaling involved in the regulation of heterocyst differentiation and for reciprocal nutrition of heterocysts and vegetative cells. Here we review various aspects of multicellularity in cyanobacterial filaments and their differentiation, including filament architecture with emphasis on the structures used for intercellular communication; we survey theoretical models that have been put forward to understand heterocyst patterning and discuss the factors that need to be considered for these models to reflect the biological entity; and finally, since cell division in filamentous cyanobacteria has the peculiarity of producing linked instead of independent cells, we review distinct aspects of cell division in these organisms.

Multicellular regulation of entropy, spatial order, and information

NASA Astrophysics Data System (ADS)

Youk, Hyun

Many multicellular systems such as tissues and microbial biofilms consist of cells that secrete and sense signalling molecules. Understanding how collective behaviours of secrete-and-sense cells is an important challenge. We combined experimental and theoretical approaches to understand multicellular coordination of gene expression and spatial pattern formation among secrete-and-sense cells. We engineered secrete-and-sense yeast cells to show that cells can collectively and permanently remember a past event by reminding each other with their secreted signalling molecule. If one cell ``forgets'' then another cell can remind it. Cell-cell communication ensures a long-term (permanent) memory by overcoming common limitations of intracellular memory. We also established a new theoretical framework inspired by statistical mechanics to understand how fields of secrete-and-sense cells form spatial patterns. We introduce new metrics - cellular entropy, cellular Hamiltonian, and spatial order index - for dynamics of cellular automata that form spatial patterns. Our theory predicts how fast any spatial patterns form, how ordered they are, and establishes cellular Hamiltonian that, like energy for non-living systems, monotonically decreases towards a minimum over time. ERC Starting Grant (MultiCellSysBio), NWO VIDI, NWO NanoFront.

Multicellular detachment generates metastatic spheroids during intra-abdominal dissemination in epithelial ovarian cancer.

PubMed

Al Habyan, Sara; Kalos, Christina; Szymborski, Joseph; McCaffrey, Luke

2018-05-23

Ovarian cancer is the most lethal gynecological cancer, where survival rates have had modest improvement over the last 30 years. Metastasis of cancer cells is a major clinical problem, and patient mortality occurs when ovarian cancer cells spread beyond the confinement of ovaries. Disseminated ovarian cancer cells typically spread within the abdomen, where ascites accumulation aids in their transit. Metastatic ascites contain multicellular spheroids, which promote chemo-resistance and recurrence. However, little is known about the origin and mechanisms through which spheroids arise. Using live-imaging of 3D culture models and animal models, we report that epithelial ovarian cancer (EOC) cells, the most common type of ovarian cancer, can spontaneously detach as either single cells or clusters. We report that clusters are more resistant to anoikis and have a potent survival advantage over single cells. Using in vivo lineage tracing, we found that multicellular spheroids arise preferentially from collective detachment, rather than aggregation in the abdomen. Finally, we report that multicellular spheroids from collective detachment are capable of seeding intra-abdominal metastases that retain intra-tumoral heterogeneity from the primary tumor.

Self-recognition of high-mannose type glycans mediating adhesion of embryonal fibroblasts.

PubMed

Yoon, Seon-Joo; Utkina, Natalia; Sadilek, Martin; Yagi, Hirokazu; Kato, Koichi; Hakomori, Sen-itiroh

2013-07-01

High-mannose type N-linked glycan with 6 mannosyl residues, termed "M6Gn2", displayed clear binding to the same M6Gn2, conjugated with ceramide mimetic (cer-m) and incorporated in liposome, or coated on polystyrene plates. However, the conjugate of M6Gn2-cer-m did not interact with complex-type N-linked glycan with various structures having multiple GlcNAc termini, conjugated with cer-m. The following observations indicate that hamster embryonic fibroblast NIL-2 K cells display homotypic autoadhesion, mediated through the self-recognition capability of high-mannose type glycans expressed on these cells: (i) NIL-2 K cells display clear binding to lectins capable of binding to high-mannose type glycans (e.g., ConA), but not to other lectins capable of binding to other carbohydrates (e.g. GS-II). (ii) NIL-2 K cells adhere strongly to plates coated with M6Gn2-cer-m, but not to plates coated with complex-type N-linked glycans having multiple GlcNAc termini, conjugated with cer-m; (iii) degree of NIL-2 K cell adhesion to plates coated with M6Gn2-cer-m showed a clear dose-dependence on the amount of M6Gn2-cer-m; and (iv) the degree of NIL-2 K adhesion to plates coated with M6Gn2-cer-m was inhibited in a dose-dependent manner by α1,4-L-mannonolactone, the specific inhibitor in high-mannose type glycans addition. These data indicate that adhesion of NIL-2 K is mediated by self-aggregation of high mannose type glycan. Further studies are to be addressed on auto-adhesion of other types of cells based on self interaction of high mannose type glycans.

Transcription factor evolution in eukaryotes and the assembly of the regulatory toolkit in multicellular lineages

PubMed Central

de Mendoza, Alex; Sebé-Pedrós, Arnau; Šestak, Martin Sebastijan; Matejčić, Marija; Torruella, Guifré; Domazet-Lošo, Tomislav; Ruiz-Trillo, Iñaki

2013-01-01

Transcription factors (TFs) are the main players in transcriptional regulation in eukaryotes. However, it remains unclear what role TFs played in the origin of all of the different eukaryotic multicellular lineages. In this paper, we explore how the origin of TF repertoires shaped eukaryotic evolution and, in particular, their role into the emergence of multicellular lineages. We traced the origin and expansion of all known TFs through the eukaryotic tree of life, using the broadest possible taxon sampling and an updated phylogenetic background. Our results show that the most complex multicellular lineages (i.e., those with embryonic development, Metazoa and Embryophyta) have the most complex TF repertoires, and that these repertoires were assembled in a stepwise manner. We also show that a significant part of the metazoan and embryophyte TF toolkits evolved earlier, in their respective unicellular ancestors. To gain insights into the role of TFs in the development of both embryophytes and metazoans, we analyzed TF expression patterns throughout their ontogeny. The expression patterns observed in both groups recapitulate those of the whole transcriptome, but reveal some important differences. Our comparative genomics and expression data reshape our view on how TFs contributed to eukaryotic evolution and reveal the importance of TFs to the origins of multicellularity and embryonic development. PMID:24277850

Direct conversion of injury-site myeloid cells to fibroblast-like cells of granulation tissue.

PubMed

Sinha, Mithun; Sen, Chandan K; Singh, Kanhaiya; Das, Amitava; Ghatak, Subhadip; Rhea, Brian; Blackstone, Britani; Powell, Heather M; Khanna, Savita; Roy, Sashwati

2018-03-05

Inflammation, following injury, induces cellular plasticity as an inherent component of physiological tissue repair. The dominant fate of wound macrophages is unclear and debated. Here we show that two-thirds of all granulation tissue fibroblasts, otherwise known to be of mesenchymal origin, are derived from myeloid cells which are likely to be wound macrophages. Conversion of myeloid to fibroblast-like cells is impaired in diabetic wounds. In cross-talk between keratinocytes and myeloid cells, miR-21 packaged in extracellular vesicles (EV) is required for cell conversion. EV from wound fluid of healing chronic wound patients is rich in miR-21 and causes cell conversion more effectively compared to that by fluid from non-healing patients. Impaired conversion in diabetic wound tissue is rescued by targeted nanoparticle-based delivery of miR-21 to macrophages. This work introduces a paradigm wherein myeloid cells are recognized as a major source of fibroblast-like cells in the granulation tissue.

Induction of human cardiomyocyte-like cells from fibroblasts by defined factors.

PubMed

Wada, Rie; Muraoka, Naoto; Inagawa, Kohei; Yamakawa, Hiroyuki; Miyamoto, Kazutaka; Sadahiro, Taketaro; Umei, Tomohiko; Kaneda, Ruri; Suzuki, Tomoyuki; Kamiya, Kaichiro; Tohyama, Shugo; Yuasa, Shinsuke; Kokaji, Kiyokazu; Aeba, Ryo; Yozu, Ryohei; Yamagishi, Hiroyuki; Kitamura, Toshio; Fukuda, Keiichi; Ieda, Masaki

2013-07-30

Heart disease remains a leading cause of death worldwide. Owing to the limited regenerative capacity of heart tissue, cardiac regenerative therapy has emerged as an attractive approach. Direct reprogramming of human cardiac fibroblasts (HCFs) into cardiomyocytes may hold great potential for this purpose. We reported previously that induced cardiomyocyte-like cells (iCMs) can be directly generated from mouse cardiac fibroblasts in vitro and vivo by transduction of three transcription factors: Gata4, Mef2c, and Tbx5, collectively termed GMT. In the present study, we sought to determine whether human fibroblasts also could be converted to iCMs by defined factors. Our initial finding that GMT was not sufficient for cardiac induction in HCFs prompted us to screen for additional factors to promote cardiac reprogramming by analyzing multiple cardiac-specific gene induction with quantitative RT-PCR. The addition of Mesp1 and Myocd to GMT up-regulated a broader spectrum of cardiac genes in HCFs more efficiently compared with GMT alone. The HCFs and human dermal fibroblasts transduced with GMT, Mesp1, and Myocd (GMTMM) changed the cell morphology from a spindle shape to a rod-like or polygonal shape, expressed multiple cardiac-specific proteins, increased a broad range of cardiac genes and concomitantly suppressed fibroblast genes, and exhibited spontaneous Ca(2+) oscillations. Moreover, the cells matured to exhibit action potentials and contract synchronously in coculture with murine cardiomyocytes. A 5-ethynyl-2'-deoxyuridine assay revealed that the iCMs thus generated do not pass through a mitotic cell state. These findings demonstrate that human fibroblasts can be directly converted to iCMs by defined factors, which may facilitate future applications in regenerative medicine.

FAP-overexpressing fibroblasts produce an extracellular matrix that enhances invasive velocity and directionality of pancreatic cancer cells

PubMed Central

2011-01-01

Background Alterations towards a permissive stromal microenvironment provide important cues for tumor growth, invasion, and metastasis. In this study, Fibroblast activation protein (FAP), a serine protease selectively produced by tumor-associated fibroblasts in over 90% of epithelial tumors, was used as a platform for studying tumor-stromal interactions. We tested the hypothesis that FAP enzymatic activity locally modifies stromal ECM (extracellular matrix) components thus facilitating the formation of a permissive microenvironment promoting tumor invasion in human pancreatic cancer. Methods We generated a tetracycline-inducible FAP overexpressing fibroblastic cell line to synthesize an in vivo-like 3-dimensional (3D) matrix system which was utilized as a stromal landscape for studying matrix-induced cancer cell behaviors. A FAP-dependent topographical and compositional alteration of the ECM was characterized by measuring the relative orientation angles of fibronectin fibers and by Western blot analyses. The role of FAP in the matrix-induced permissive tumor behavior was assessed in Panc-1 cells in assorted matrices by time-lapse acquisition assays. Also, FAP+ matrix-induced regulatory molecules in cancer cells were determined by Western blot analyses. Results We observed that FAP remodels the ECM through modulating protein levels, as well as through increasing levels of fibronectin and collagen fiber organization. FAP-dependent architectural/compositional alterations of the ECM promote tumor invasion along characteristic parallel fiber orientations, as demonstrated by enhanced directionality and velocity of pancreatic cancer cells on FAP+ matrices. This phenotype can be reversed by inhibition of FAP enzymatic activity during matrix production resulting in the disorganization of the ECM and impeded tumor invasion. We also report that the FAP+ matrix-induced tumor invasion phenotype is β1-integrin/FAK mediated. Conclusion Cancer cell invasiveness can be affected by

In Vitro Effects of Pirfenidone on Cardiac Fibroblasts: Proliferation, Myofibroblast Differentiation, Migration and Cytokine Secretion

PubMed Central

Shi, Qiang; Liu, Xiaoyan; Bai, Yuanyuan; Cui, Chuanjue; Li, Jun; Li, Yishi; Hu, Shengshou; Wei, Yingjie

2011-01-01

Cardiac fibroblasts (CFs) are the primary cell type responsible for cardiac fibrosis during pathological myocardial remodeling. Several studies have illustrated that pirfenidone (5-methyl-1-phenyl-2-[1H]-pyridone) attenuates cardiac fibrosis in different animal models. However, the effects of pirfenidone on cardiac fibroblast behavior have not been examined. In this study, we investigated whether pirfenidone directly modulates cardiac fibroblast behavior that is important in myocardial remodeling such as proliferation, myofibroblast differentiation, migration and cytokine secretion. Fibroblasts were isolated from neonatal rat hearts and bioassays were performed to determine the effects of pirfenidone on fibroblast function. We demonstrated that treatment of CFs with pirfenidone resulted in decreased proliferation, and attenuated fibroblast α-smooth muscle actin expression and collagen contractility. Boyden chamber assay illustrated that pirfenidone inhibited fibroblast migration ability, probably by decreasing the ratio of matrix metalloproteinase-9 to tissue inhibitor of metalloproteinase-1. Furthermore, pirfenidone attenuated the synthesis and secretion of transforming growth factor-β1 but elevated that of interleukin-10. These direct and pleiotropic effects of pirfenidone on cardiac fibroblasts point to its potential use in the treatment of adverse myocardial remodeling. PMID:22132230

Rapid formation of size-controllable multicellular spheroids via 3D acoustic tweezers.

PubMed

Chen, Kejie; Wu, Mengxi; Guo, Feng; Li, Peng; Chan, Chung Yu; Mao, Zhangming; Li, Sixing; Ren, Liqiang; Zhang, Rui; Huang, Tony Jun

2016-07-05

The multicellular spheroid is an important 3D cell culture model for drug screening, tissue engineering, and fundamental biological research. Although several spheroid formation methods have been reported, the field still lacks high-throughput and simple fabrication methods to accelerate its adoption in drug development industry. Surface acoustic wave (SAW) based cell manipulation methods, which are known to be non-invasive, flexible, and high-throughput, have not been successfully developed for fabricating 3D cell assemblies or spheroids, due to the limited understanding on SAW-based vertical levitation. In this work, we demonstrated the capability of fabricating multicellular spheroids in the 3D acoustic tweezers platform. Our method used drag force from microstreaming to levitate cells in the vertical direction, and used radiation force from Gor'kov potential to aggregate cells in the horizontal plane. After optimizing the device geometry and input power, we demonstrated the rapid and high-throughput nature of our method by continuously fabricating more than 150 size-controllable spheroids and transferring them to Petri dishes every 30 minutes. The spheroids fabricated by our 3D acoustic tweezers can be cultured for a week with good cell viability. We further demonstrated that spheroids fabricated by this method could be used for drug testing. Unlike the 2D monolayer model, HepG2 spheroids fabricated by the 3D acoustic tweezers manifested distinct drug resistance, which matched existing reports. The 3D acoustic tweezers based method can serve as a novel bio-manufacturing tool to fabricate complex 3D cell assembles for biological research, tissue engineering, and drug development.

High inorganic phosphate causes DNMT1 phosphorylation and subsequent fibrotic fibroblast activation

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

Tan, Xiaoying; Department of Cardiology and Pneumology, Göttingen University Medical Center, Georg August University, Göttingen; Xu, Xingbo

Phosphate is an essential constituent of critical cellular functions including energy metabolism, nucleic acid synthesis and phosphorylation-dependent cell signaling. Increased plasma phosphate levels are an independent risk factor for lowered life-expectancy as well as for heart and kidney failure. Nevertheless, direct cellular effects of elevated phosphate concentrations within the microenvironment are poorly understood and have been largely neglected in favor of phosphor-regulatory hormones. Because interstitial fibrosis is the common determinant of chronic progressive kidney disease, and because fibroblasts are major mediators of fibrogenesis, we here explored the effect of high extracellular phosphate levels on renal fibroblasts. We demonstrate that highmore » inorganic phosphate directly induces fibrotic fibroblast activation associated with increased proliferative activity, increased expression of α-smooth muscle actin and increased synthesis of type I collagen. We further demonstrate that such fibroblast activation is dependent on phosphate influx, aberrant phosphorylation of DNA methyltransferase DNMT1 and aberrant CpG island promoter methylation. In summary, our studies demonstrate that elevated phosphate concentrations induce pro-fibrotic fibroblast activation independent of phospho-regulatory hormones. - Highlights: • We exposed human kidney fibroblasts to media containing 1 mM or 3 mM phosphate. • Increased phosphate influx causes phosphorylation of DNA methyltransferase Dnmt1. • Phosphorylated Dnmt1 causes promoter methylation and transcriptional silencing of RASAL1. • Depletion of RASAL1 causes increased intrinsic Ras-GTP activity and fibroblast activation. • Inorganic phosphate causes fibroblast activation independent of phospho-regulatory hormones.« less

[Self-directed learning in nursing students with different background factors].

PubMed

Kao, Yu-Hsiu; Yu, Chu-Wei; Kuo, Shu-Yi; Kuang, I-Hsiu

2013-08-01

Fostering self-directed learning skills in nursing students may provide a foundation for improving the specialty knowledge of these nurses. This study examines the current status of nursing student self-directed learning behavior and explores how different background factors impact self-directed learning. This research design used a cross-sectional survey and convenience sampling. A total of 550 questionnaires were distributed to participants in enrolled in nursing programs at a 2-year nursing program at an institute of technology in northern Taiwan and a 4-year nursing program at an institute of technology in southern Taiwan. A convenience sampling was used to collect data, with 537 valid questionnaires used in data analysis. Results indicated that the self-directed learning and self-management of nursing students between 20-21 years old was significantly higher than those of students between 18-19 years old. Self-directed learning, desire of learning and self-control in 2-year nursing students were significantly higher than in 4-year and extension education department nursing student participants. Two-year nursing students had the highest self-management scores, followed by extension education department participants and 4-year nursing students. Finally, participants who associated highly with the nursing profession earned the highest self-directed total score, followed by those participants who associated generally and those who associated mildly. The results recommend that teachers at nursing institutes help students develop self-directed learning. Results also recommend teachers increase their students' association with the nursing specialty through understanding the impact of different background factors on self-directed learning.

Multidrug resistance characterization in multicellular tumour spheroids from two human lung cancer cell lines.

PubMed

Barrera-Rodríguez, Raúl; Fuentes, Jorge Morales

2015-01-01

Most of the knowledge about the mechanisms of multidrug resistance in lung cancer has been achieved through the use of cell lines isolated from tumours cultivated either in suspensions of isolated cells or in monolayers and following exposition to different cytostatic agents. However, tumour cell lines growing as multicellular tumour spheroids (MTS) frequently develop multicellular resistance in a drug-independent form. The aim of this study was to characterize the phenotypic and functional differences between two human NSCLC cell lines (INER-37 and INER-51) grown as traditional monolayer cultures versus as MTS. After 72 hours treatment with anticancer drugs, chemosensitivity in monolayers and tumour spheroids cultures was assessed using MTT assay. Reverse transcription-polymerase chain reaction was employed to detect the mRNAs of multidrug resistance-related genes. The expression of P-gp was analyzed by immunohistochemical staining and cell cycle profiles were analyzed using FACS. The results indicate that when grown as MTS each lung cancer cell line had different morphologies as well as and abrogation of cell proliferation with decrease of the G2/M phase. Also, MTS acquired multicellular resistance to several chemotherapeutic agents in only a few days of culture which were accomplished by significant changes in the expression of MDR-related genes. Overall, the MTS culture changed the cellular response to drugs nevertheless each of the cell lines studied seems to implement different mechanisms to acquire multicellular resistance.

Interactive Multimedia Instruction for Training Self-Directed Learning Techniques

DTIC Science & Technology

2016-06-01

feedback and input on the content, format, and pedagogical approach of the lesson. This survey could be e-mailed to the principal ARI researcher for...peers in self-directed learning. Some examples of the metaphorical relationships and common examples woven into this IMI are identified in Table 1...20 Table 1 Metaphorical Relationships and Illustrations Used in Self-Directed Learning Training Military or Common Example Self-Directed

The development and structure of thick-walled, multicellular, aerial spores in Diheterospora chlamydosporia (=Verticillium chlamydosporium).

PubMed

Cambell, W P; Griffiths, D A

1975-07-01

The aerial, thick-walled spores in Diheterospara chlamydosporia arose as terminal swellings on erect hyphae. Repeated septation of the continuously swelling spore resulted in a multicellular structure. Immediately after the onset of septation secondary wall material was laid down between the two-layered primary wall and the plasmalemma. The presence of secondary wall material indicates that the multicellular spore is a dictyochlamydospore and not an aleuriospore. The relationship between chlamydospores and aleuriospores in other fungi is discussed.

Combined CSL and p53 downregulation promotes cancer-associated fibroblast activation

PubMed Central

Procopio, Maria-Giuseppina; Laszlo, Csaba; Labban, Dania Al; Kim, Dong Eun; Bordignon, Pino; Jo, Seunghee; Goruppi, Sandro; Menietti, Elena; Ostano, Paola; Ala, Ugo; Provero, Paolo; Hoetzenecker, Wolfram; Neel, Victor; Kilarski, Witek; Swartz, Melody A.; Brisken, Cathrin; Lefort, Karine; Dotto, G. Paolo

2015-01-01

Stromal fibroblast senescence has been linked to aging-associated cancer risk. However, density and proliferation of cancer-associated fibroblasts (CAF) are frequently increased. Loss or down-modulation of the Notch effector CSL/RBP-Jκ in dermal fibroblasts is sufficient for CAF activation and ensuing keratinocyte-derived tumors. We report that CSL silencing induces senescence of primary fibroblasts from dermis, oral mucosa, breast and lung. CSL functions in these cells as direct repressor of multiple senescence- and CAF-effector genes. It also physically interacts with p53, repressing its activity. CSL is down-modulated in stromal fibroblasts of premalignant skin actinic keratosis lesions and squamous cell carcinomas (SCC), while p53 expression and function is down-modulated only in the latter, with paracrine FGF signaling as likely culprit. Concomitant loss of CSL and p53 overcomes fibroblast senescence, enhances expression of CAF effectors and promotes stromal and cancer cell expansion. The findings support a CAF activation/stromal co-evolution model under convergent CSL/p53 control. PMID:26302407

Lipid profiling of parkin-mutant human skin fibroblasts.

PubMed

Lobasso, Simona; Tanzarella, Paola; Vergara, Daniele; Maffia, Michele; Cocco, Tiziana; Corcelli, Angela

2017-12-01

Parkin mutations are a major cause of early-onset Parkinson's disease (PD). The impairment of protein quality control system together with defects in mitochondria and autophagy process are consequences of the lack of parkin, which leads to neurodegeneration. Little is known about the role of lipids in these alterations of cell functions. In the present study, parkin-mutant human skin primary fibroblasts have been considered as cellular model of PD to investigate on possible lipid alterations associated with the lack of parkin protein. Dermal fibroblasts were obtained from two unrelated PD patients with different parkin mutations and their lipid compositions were compared with that of two control fibroblasts. The lipid extracts of fibroblasts have been analyzed by combined matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF/MS) and thin-layer chromatography (TLC). In parallel, we have performed direct MALDI-TOF/MS lipid analyses of intact fibroblasts by skipping lipid extraction steps. Results show that the proportions of some phospholipids and glycosphingolipids were altered in the lipid profiles of parkin-mutant fibroblasts. The detected higher level of gangliosides, phosphatidylinositol, and phosphatidylserine could be linked to dysfunction of autophagy and mitochondrial turnover; in addition, the lysophosphatidylcholine increase could represent the marker of neuroinflammatory state, a well-known component of PD. © 2017 Wiley Periodicals, Inc.

PhysiCell: An open source physics-based cell simulator for 3-D multicellular systems.

PubMed

Ghaffarizadeh, Ahmadreza; Heiland, Randy; Friedman, Samuel H; Mumenthaler, Shannon M; Macklin, Paul

2018-02-01

Many multicellular systems problems can only be understood by studying how cells move, grow, divide, interact, and die. Tissue-scale dynamics emerge from systems of many interacting cells as they respond to and influence their microenvironment. The ideal "virtual laboratory" for such multicellular systems simulates both the biochemical microenvironment (the "stage") and many mechanically and biochemically interacting cells (the "players" upon the stage). PhysiCell-physics-based multicellular simulator-is an open source agent-based simulator that provides both the stage and the players for studying many interacting cells in dynamic tissue microenvironments. It builds upon a multi-substrate biotransport solver to link cell phenotype to multiple diffusing substrates and signaling factors. It includes biologically-driven sub-models for cell cycling, apoptosis, necrosis, solid and fluid volume changes, mechanics, and motility "out of the box." The C++ code has minimal dependencies, making it simple to maintain and deploy across platforms. PhysiCell has been parallelized with OpenMP, and its performance scales linearly with the number of cells. Simulations up to 105-106 cells are feasible on quad-core desktop workstations; larger simulations are attainable on single HPC compute nodes. We demonstrate PhysiCell by simulating the impact of necrotic core biomechanics, 3-D geometry, and stochasticity on the dynamics of hanging drop tumor spheroids and ductal carcinoma in situ (DCIS) of the breast. We demonstrate stochastic motility, chemical and contact-based interaction of multiple cell types, and the extensibility of PhysiCell with examples in synthetic multicellular systems (a "cellular cargo delivery" system, with application to anti-cancer treatments), cancer heterogeneity, and cancer immunology. PhysiCell is a powerful multicellular systems simulator that will be continually improved with new capabilities and performance improvements. It also represents a significant

PhysiCell: An open source physics-based cell simulator for 3-D multicellular systems

PubMed Central

Ghaffarizadeh, Ahmadreza; Mumenthaler, Shannon M.

2018-01-01

Many multicellular systems problems can only be understood by studying how cells move, grow, divide, interact, and die. Tissue-scale dynamics emerge from systems of many interacting cells as they respond to and influence their microenvironment. The ideal “virtual laboratory” for such multicellular systems simulates both the biochemical microenvironment (the “stage”) and many mechanically and biochemically interacting cells (the “players” upon the stage). PhysiCell—physics-based multicellular simulator—is an open source agent-based simulator that provides both the stage and the players for studying many interacting cells in dynamic tissue microenvironments. It builds upon a multi-substrate biotransport solver to link cell phenotype to multiple diffusing substrates and signaling factors. It includes biologically-driven sub-models for cell cycling, apoptosis, necrosis, solid and fluid volume changes, mechanics, and motility “out of the box.” The C++ code has minimal dependencies, making it simple to maintain and deploy across platforms. PhysiCell has been parallelized with OpenMP, and its performance scales linearly with the number of cells. Simulations up to 105-106 cells are feasible on quad-core desktop workstations; larger simulations are attainable on single HPC compute nodes. We demonstrate PhysiCell by simulating the impact of necrotic core biomechanics, 3-D geometry, and stochasticity on the dynamics of hanging drop tumor spheroids and ductal carcinoma in situ (DCIS) of the breast. We demonstrate stochastic motility, chemical and contact-based interaction of multiple cell types, and the extensibility of PhysiCell with examples in synthetic multicellular systems (a “cellular cargo delivery” system, with application to anti-cancer treatments), cancer heterogeneity, and cancer immunology. PhysiCell is a powerful multicellular systems simulator that will be continually improved with new capabilities and performance improvements. It also

Droplet-based microfluidic system to form and separate multicellular spheroids using magnetic nanoparticles.

PubMed

Yoon, Sungjun; Kim, Jeong Ah; Lee, Seung Hwan; Kim, Minsoo; Park, Tai Hyun

2013-04-21

The importance of creating a three-dimensional (3-D) multicellular spheroid has recently been gaining attention due to the limitations of monolayer cell culture to precisely mimic in vivo structure and cellular interactions. Due to this emerging interest, researchers have utilized new tools, such as microfluidic devices, that allow high-throughput and precise size control to produce multicellular spheroids. We have developed a droplet-based microfluidic system that can encapsulate both cells and magnetic nanoparticles within alginate beads to mimic the function of a multicellular tumor spheroid. Cells were entrapped within the alginate beads along with magnetic nanoparticles, and the beads of a relatively uniform size (diameters of 85% of the beads were 170-190 μm) were formed in the oil phase. These beads were passed through parallel streamlines of oil and culture medium, where the beads were magnetically transferred into the medium phase from the oil phase using an external magnetic force. This microfluidic chip eliminates additional steps for collecting the spheroids from the oil phase and transferring them to culture medium. Ultimately, the overall spheroid formation process can be achieved on a single microchip.

The Relationship between Self-Direction and Wellness among Graduate Students.

ERIC Educational Resources Information Center

Owen, T. Ross

1999-01-01

Self Directed Learning Readiness Scale and a wellness measure were completed by 185 graduate students. Creativity significantly correlated with wellness; intellectual wellness and spirituality/values correlated with self-directed learning. Self-directed learners appear to feel strongly about creative expression, and creative pursuits have the…

Activation and synchronization of the oscillatory morphodynamics in multicellular monolayer

PubMed Central

Lin, Shao-Zhen; Li, Bo; Lan, Ganhui; Feng, Xi-Qiao

2017-01-01

Oscillatory morphodynamics provides necessary mechanical cues for many multicellular processes. Owing to their collective nature, these processes require robustly coordinated dynamics of individual cells, which are often separated too distantly to communicate with each other through biomaterial transportation. Although it is known that the mechanical balance generally plays a significant role in the systems’ morphologies, it remains elusive whether and how the mechanical components may contribute to the systems’ collective morphodynamics. Here, we study the collective oscillations in the Drosophila amnioserosa tissue to elucidate the regulatory roles of the mechanical components. We identify that the tensile stress is the key activator that switches the collective oscillations on and off. This regulatory role is shown analytically using the Hopf bifurcation theory. We find that the physical properties of the tissue boundary are directly responsible for synchronizing the oscillatory intensity and polarity of all inner cells and for orchestrating the spatial oscillation patterns inthe tissue. PMID:28716911

Fibroblasts maintained in 3 dimensions show a better differentiation state and higher sensitivity to estrogens

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

Montani, Claudia; Steimberg, Nathalie; Boniotti, Jennifer

2014-11-01

Cell differentiation and response to hormonal signals were studied in a 3D environment on an in-house generated mouse fibroblast cell line expressing a reporter gene under the control of estrogen responsive sequences (EREs). 3D cell culture conditions were obtained in a Rotary Cell Culture System; (RCCS™), a microgravity based bioreactor that promotes the aggregation of cells into multicellular spheroids (MCS). In this bioreactor the cells maintained a better differentiated phenotype and more closely resembled in vivo tissue. The RCCS™ cultured fibroblasts showed higher expression of genes regulating cell assembly, differentiation and hormonal functions. Microarray analysis showed that genes related tomore » cell cycle, proliferation, cytoskeleton, migration, adhesion and motility were all down-regulated in 3D as compared to 2D conditions, as well as oncogene expression and inflammatory cytokines. Controlled remodeling of ECM, which is an essential aspect of cell organization, homeostasis and tissue was affected by the culture method as assessed by immunolocalization of β-tubulin. Markers of cell organization, homeostasis and tissue repair, metalloproteinase 2 (MMP2) and its physiological inhibitor (TIMP4) changed expression in association with the relative formation of cell aggregates. The fibroblasts cultured in the RCCS™ maintain a better responsiveness to estrogens, measured as expression of ERα and regulation of an ERE-dependent reporter and of the endogenous target genes CBP, Rarb, MMP1 and Dbp. Our data highlight the interest of this 3D culture model for its potential application in the field of cell response to hormonal signals and the pharmaco-toxicological analyses of chemicals and natural molecules endowed of estrogenic potential. - Highlights: • We here characterized the first cell line derived from an estrogen reporter mouse. • In the RCCS cells express an immortalized behavior but not a transformed phenotype. • The RCCS provides a

Inefficient reprogramming of fibroblasts into cardiomyocytes using Gata4, Mef2c, Tbx5

PubMed Central

Chen, J.X.; Krane, M.; Deutsch, M. A.; Wang, L.; Rav-Acha, M.; Gregoire, S.; Engels, M. C.; Rajarajan, K.; Karra, R.; Abel, E. D.; Wu, J. C.; Milan, D.; Wu, S. M.

2012-01-01

Rationale Direct reprogramming of fibroblasts into cardiomyocytes is a novel strategy for cardiac regeneration. However, the key determinants involved in this process are unknown. Objective To assess the efficiency of direct fibroblast reprogramming via viral overexpression of GATA4, Mef2c, and Tbx5 (GMT). Methods and Results We induced GMT overexpression in murine tail tip fibroblasts (TTFs) and cardiac fibroblasts (CFs) from multiple lines of transgenic mice carrying different cardiomyocyte lineage reporters. We found that the induction of GMT overexpression in TTFs and CFs is inefficient at inducing molecular and electrophysiological phenotypes of mature cardiomyocytes. In addition, transplantation of GMT infected CFs into injured mouse hearts resulted in decreased cell survival with minimal induction of cardiomyocyte genes. Conclusions Significant challenges remain in our ability to convert fibroblasts into cardiomyocyte-like cells and a greater understanding of cardiovascular epigenetics is needed to increase the translational potential of this strategy. PMID:22581928

Human skeletal muscle fibroblasts stimulate in vitro myogenesis and in vivo muscle regeneration.

PubMed

Mackey, Abigail L; Magnan, Mélanie; Chazaud, Bénédicte; Kjaer, Michael

2017-08-01

Accumulation of skeletal muscle extracellular matrix is an unfavourable characteristic of many muscle diseases, muscle injury and sarcopenia. The extent of cross-talk between fibroblasts, as the source of matrix protein, and satellite cells in humans is unknown. We studied this in human muscle biopsies and cell-culture studies. We observed a strong stimulation of myogenesis by human fibroblasts in cell culture. In biopsies collected 30 days after a muscle injury protocol, fibroblast number increased to four times control levels, where fibroblasts were found to be preferentially located immediately surrounding regenerating muscle fibres. These novel findings indicate an important role for fibroblasts in supporting the regeneration of muscle fibres, potentially through direct stimulation of satellite cell differentiation and fusion, and contribute to understanding of cell-cell cross-talk during physiological and pathological muscle remodelling. Accumulation of skeletal muscle extracellular matrix is an unfavourable characteristic of many muscle diseases, muscle injury and sarcopenia. In addition to the indispensable role satellite cells play in muscle regeneration, there is emerging evidence in rodents for a regulatory influence on fibroblast activity. However, the influence of fibroblasts on satellite cells and muscle regeneration in humans is unknown. The purpose of this study was to investigate this in vitro and during in vivo regeneration in humans. Following a muscle injury protocol in young healthy men (n = 7), the number of fibroblasts (TCF7L2+), satellite cells (Pax7+), differentiating myogenic cells (myogenin+) and regenerating fibres (neonatal/embryonic myosin+) was determined from biopsy cross-sections. Fibroblasts and myogenic precursor cells (MPCs) were also isolated from human skeletal muscle (n = 4) and co-cultured using different cell ratios, with the two cell populations either in direct contact with each other or separated by a permeable

Self-organization principles of intracellular pattern formation.

PubMed

Halatek, J; Brauns, F; Frey, E

2018-05-26

Dynamic patterning of specific proteins is essential for the spatio-temporal regulation of many important intracellular processes in prokaryotes, eukaryotes and multicellular organisms. The emergence of patterns generated by interactions of diffusing proteins is a paradigmatic example for self-organization. In this article, we review quantitative models for intracellular Min protein patterns in Escherichia coli , Cdc42 polarization in Saccharomyces cerevisiae and the bipolar PAR protein patterns found in Caenorhabditis elegans By analysing the molecular processes driving these systems we derive a theoretical perspective on general principles underlying self-organized pattern formation. We argue that intracellular pattern formation is not captured by concepts such as 'activators', 'inhibitors' or 'substrate depletion'. Instead, intracellular pattern formation is based on the redistribution of proteins by cytosolic diffusion, and the cycling of proteins between distinct conformational states. Therefore, mass-conserving reaction-diffusion equations provide the most appropriate framework to study intracellular pattern formation. We conclude that directed transport, e.g. cytosolic diffusion along an actively maintained cytosolic gradient, is the key process underlying pattern formation. Thus the basic principle of self-organization is the establishment and maintenance of directed transport by intracellular protein dynamics.This article is part of the theme issue 'Self-organization in cell biology'. © 2018 The Authors.

Stromagenesis: the changing face of fibroblastic microenvironments during tumor progression.

PubMed

Beacham, Dorothy A; Cukierman, Edna

2005-10-01

During tumorigenesis, reciprocal changes in stromal fibroblasts and tumor cells induce changes to the neoplastic microenvironmental landscape. In stromagenesis, both the complex network of bi-directional stromal fibroblastic signaling pathways and the stromal extracellular matrix are modified. The presence of a 'primed' stroma during the early, reversible stage of tumorigenesis is optimal for stromal-directed therapeutic intervention. Three-dimensional (3D) cell culture systems have been developed that mimic the in vivo microenvironment. These systems provide unique experimental tools to identify early alterations in stromagenesis that are supportive of tumor progression with the ultimate goal of blocking neoplastic permissiveness and restoring normal phenotypes.

Hedgehog signaling contributes to basic fibroblast growth factor-regulated fibroblast migration

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

Zhu, Zhong Xin; Sun, Cong Cong; Wenzhou People's Hospital, Wenzhou, Zhejiang

Fibroblast migration is a central process in skin wound healing, which requires the coordination of several types of growth factors. bFGF, a well-known fibroblast growth factor (FGF), is able to accelerate fibroblast migration; however, the underlying mechanism of bFGF regulation fibroblast migration remains unclear. Through the RNA-seq analysis, we had identified that the hedgehog (Hh) canonical pathway genes including Smoothened (Smo) and Gli1, were regulated by bFGF. Further analysis revealed that activation of the Hh pathway via up-regulation of Smo promoted fibroblast migration, invasion, and skin wound healing, but which significantly reduced by GANT61, a selective antagonist of Gli1/Gli2. Westernmore » blot analyses and siRNA transfection assays demonstrated that Smo acted upstream of phosphoinositide 3-kinase (PI3K)-c-Jun N-terminal kinase (JNK)-β-catenin to promote cell migration. Moreover, RNA-seq and qRT-PCR analyses revealed that Hh pathway genes including Smo and Gli1 were under control of β-catenin, suggesting that β-catenin turn feedback activates Hh signaling. Taken together, our analyses identified a new bFGF-regulating mechanism by which Hh signaling regulates human fibroblast migration, and the data presented here opens a new avenue for the wound healing therapy. - Highlights: • bFGF regulates Hedgehog (Hh) signaling in fibroblasts. • The Smo and Gli two master regulators of Hh signaling positively regulate fibroblast migration. • Smo facilitates β-catenin nuclear translocation via activation PI3K/JNK/GSK3β. • β-catenin positively regulates fibroblast cell migration and the expression of Hh signaling genes including Smo and Gli.« less

Self-Directed Learning with Feedback

ERIC Educational Resources Information Center

Choi, Youngeun; Anderson, William

2016-01-01

This article describes a weekly writing assignment named SelFeed (Self-Directed Learning with Feedback), in which students are asked to identify their own questions relevant to the lecture content and provide logical answers.

Deconstructing the effect of self-directed study on episodic memory

PubMed Central

Markant, Douglas; DuBrow, Sarah; Davachi, Lila; Gureckis, Todd M.

2014-01-01

Self-directed learning is often associated with better long-term memory retention, however, the mechanisms that underlie this advantage remain poorly understood. This series of experiments was designed to “deconstruct” the notion of self-directed learning in order to better identify the factors most responsible for these improvements to memory. In particular, we isolate the memory advantage that comes from controlling the content of study episodes from the advantage that comes from controlling the timing of those episodes. Across four experiments, self-directed learning significantly enhanced recognition memory relative to passive observation. However, the advantage for self-directed learning was found to be present even under extremely minimal conditions of volitional control (simply pressing a button when ready to advance to the next item). Our results suggest that improvements to memory following self-directed encoding may be related to the ability to coordinate stimulus presentation with the learner’s current preparatory or attentional state, and highlight the need to consider the range of cognitive control processes involved in and influenced by self-directed study. PMID:24941938

MicroRNA-mediated non-viral direct conversion of embryonic fibroblasts to cardiomyocytes: comparison of commercial and synthetic non-viral vectors.

PubMed

Kim, Hyosuk; Kim, Dongkyu; Ku, Sook Hee; Kim, Kwangmeyung; Kim, Sun Hwa; Kwon, Ick Chan

Technological advances opened up new ways of directing cell fate conversion from one cell lineage to another. The direct cell conversion technique has recently attracted much attention in regenerative medicine to treat devastated organs and tissues, particularly having limited regenerative capacity such as the heart and brain. Unfortunately, its clinical application is severely limited due to a safety concern and immunogenicity of viral vectors, as human gene therapy did in the beginning stages. In this study, we examined the possibility of adopting non-viral vectors to direct cell conversion from mouse embryonic fibroblasts to induced cardiomyocytes (iCM) by transient transfection of four types of chemically synthesized micro-RNA mimics (miRNA-1, 133, 208, and 499). Herein, we tested several commercial and synthetic non-viral gene delivery carriers, which could be divided into three different categories: polymers [branched PEI (bPEI), bioreducible PEI (PEI-SS), deoxycholic acid-conjugated PEI (DA-PEI), jetPEI™, SuperFect™], lipids (Lipofectamine 2000™), and peptides (PepMute™). According to the analyses of physicochemical properties, cellular uptake, and cytotoxicity of the carrier/miRNA complexes, DA-PEI exhibited excellent miRNA delivery efficiency to mouse embryonic fibroblasts. One week after a single treatment of DA-PEI/miRNA without other adjuvants, the cells started to express cardiomyocyte-specific markers, such as α-actinin and α-MHC, indicating the formation of cardiomyocyte-like cells. Although the overall frequency of non-viral vector induced cardiomyogenic transdifferentiation was quite low (ca. 0.2%), this study can provide compelling support to develop clinically applicable transdifferentiation techniques.

Direct stimulation of human fibroblasts by nCeO2 in vitro is attenuated with an amorphous silica coating.

PubMed

Davidson, Donna C; Derk, Raymond; He, Xiaoqing; Stueckle, Todd A; Cohen, Joel; Pirela, Sandra V; Demokritou, Philip; Rojanasakul, Yon; Wang, Liying

2016-05-04

Nano-scaled cerium oxide (nCeO2) is used in a variety of applications, including use as a fuel additive, catalyst, and polishing agent, yet potential adverse health effects associated with nCeO2 exposure remain incompletely understood. Given the increasing utility and demand for engineered nanomaterials (ENMs) such as nCeO2, "safety-by-design" approaches are currently being sought, meaning that the physicochemical properties (e.g., size and surface chemistry) of the ENMs are altered in an effort to maximize functionality while minimizing potential toxicity. In vivo studies have shown in a rat model that inhaled nCeO2 deposited deep in the lung and induced fibrosis. However, little is known about how the physicochemical properties of nCeO2, or the coating of the particles with a material such as amorphous silica (aSiO2), may affect the bio-activity of these particles. Thus, we hypothesized that the physicochemical properties of nCeO2 may explain its potential to induce fibrogenesis, and that a nano-thin aSiO2 coating on nCeO2 may counteract that effect. Primary normal human lung fibroblasts were treated at occupationally relevant doses with nCeO2 that was either left uncoated or was coated with aSiO2 (amsCeO2). Subsequently, fibroblasts were analyzed for known hallmarks of fibrogenesis, including cell proliferation and collagen production, as well as the formation of fibroblastic nodules. The results of this study are consistent with this hypothesis, as we found that nCeO2 directly induced significant production of collagen I and increased cell proliferation in vitro, while amsCeO2 did not. Furthermore, treatment of fibroblasts with nCeO2, but not amsCeO2, significantly induced the formation of fibroblastic nodules, a clear indicator of fibrogenicity. Such in vitro data is consistent with recent in vivo observations using the same nCeO2 nanoparticles and relevant doses. This effect appeared to be mediated through TGFβ signaling since chemical inhibition of the TGF�

Cardiogenic Genes Expressed in Cardiac Fibroblasts Contribute to Heart Development and Repair

PubMed Central

Furtado, Milena B.; Costa, Mauro W.; Pranoto, Edward Adi; Salimova, Ekaterina; Pinto, Alex; Lam, Nicholas T.; Park, Anthony; Snider, Paige; Chandran, Anjana; Harvey, Richard P.; Boyd, Richard; Conway, Simon J.; Pearson, James; Kaye, David M.; Rosenthal, Nadia A.

2014-01-01

Rationale Cardiac fibroblasts are critical to proper heart function through multiple interactions with the myocardial compartment but appreciation of their contribution has suffered from incomplete characterization and lack of cell-specific markers. Objective To generate an unbiased comparative gene expression profile of the cardiac fibroblast pool, identify and characterize the role of key genes in cardiac fibroblast function, and determine their contribution to myocardial development and regeneration. Methods and Results High-throughput cell surface and intracellular profiling of cardiac and tail fibroblasts identified canonical MSC and a surprising number of cardiogenic genes, some expressed at higher levels than in whole heart. Whilst genetically marked fibroblasts contributed heterogeneously to interstitial but not cardiomyocyte compartments in infarcted hearts, fibroblast-restricted depletion of one highly expressed cardiogenic marker, Tbx20, caused marked myocardial dysmorphology and perturbations in scar formation upon myocardial infarction. Conclusions The surprising transcriptional identity of cardiac fibroblasts, the adoption of cardiogenic gene programs and direct contribution to cardiac development and repair provokes alternative interpretations for studies on more specialized cardiac progenitors, offering a novel perspective for reinterpreting cardiac regenerative therapies. PMID:24650916

T lymphocyte mediated lysis of mitomycin C treated Tenon's capsule fibroblasts.

PubMed

Crowston, J G; Chang, L H; Daniels, J T; Khaw, P T; Akbar, A N

2004-03-01

To evaluate the effect of T cell co-culture on mitomycin C treated and untreated Tenon's capsule fibroblasts. IL-2 dependent allogeneic T cells were incubated over a monolayer of mitomycin C treated or control fibroblasts. Fibroblast numbers were evaluated by direct counts using phase contrast microscopy. To determine whether T cell mediated lysis was a consequence of MHC mismatch, co-culture experiments were repeated with autologous T cells. The effect of Fas receptor blockade was established by co-incubation with a Fas blocking (M3) antibody. T cell co-culture resulted in a dramatic reduction in fibroblast survival compared to mitomycin C treatment alone (p = 0.032). T cell killing required fibroblast/lymphocyte cell to cell contact and was observed in both allogeneic and autologous co-culture experiments. Fas blocking antibodies did not significantly inhibit T cell killing (p = 0.39). T cells augment mitomycin C treated fibroblast death in vitro. Similar mechanisms may contribute to the cytotoxic effect of mitomycin C in vivo and account for the largely hypocellular drainage blebs that are observed clinically.

FAP-overexpressing fibroblasts produce an extracellular matrix that enhances invasive velocity and directionality of pancreatic cancer cells.

PubMed

Lee, Hyung-Ok; Mullins, Stefanie R; Franco-Barraza, Janusz; Valianou, Matthildi; Cukierman, Edna; Cheng, Jonathan D

2011-06-13

Alterations towards a permissive stromal microenvironment provide important cues for tumor growth, invasion, and metastasis. In this study, Fibroblast activation protein (FAP), a serine protease selectively produced by tumor-associated fibroblasts in over 90% of epithelial tumors, was used as a platform for studying tumor-stromal interactions. We tested the hypothesis that FAP enzymatic activity locally modifies stromal ECM (extracellular matrix) components thus facilitating the formation of a permissive microenvironment promoting tumor invasion in human pancreatic cancer. We generated a tetracycline-inducible FAP overexpressing fibroblastic cell line to synthesize an in vivo-like 3-dimensional (3D) matrix system which was utilized as a stromal landscape for studying matrix-induced cancer cell behaviors. A FAP-dependent topographical and compositional alteration of the ECM was characterized by measuring the relative orientation angles of fibronectin fibers and by Western blot analyses. The role of FAP in the matrix-induced permissive tumor behavior was assessed in Panc-1 cells in assorted matrices by time-lapse acquisition assays. Also, FAP+ matrix-induced regulatory molecules in cancer cells were determined by Western blot analyses. We observed that FAP remodels the ECM through modulating protein levels, as well as through increasing levels of fibronectin and collagen fiber organization. FAP-dependent architectural/compositional alterations of the ECM promote tumor invasion along characteristic parallel fiber orientations, as demonstrated by enhanced directionality and velocity of pancreatic cancer cells on FAP+ matrices. This phenotype can be reversed by inhibition of FAP enzymatic activity during matrix production resulting in the disorganization of the ECM and impeded tumor invasion. We also report that the FAP+ matrix-induced tumor invasion phenotype is β1-integrin/FAK mediated. Cancer cell invasiveness can be affected by alterations in the tumor

Development of the Self-Directed Learning Skills Scale

ERIC Educational Resources Information Center

Ayyildiz, Yildizay; Tarhan, Leman

2015-01-01

The purpose of this study was to develop a valid and reliable scale for assessing high school students' self-directed learning skills. Based on a literature review and data obtained from similar instruments, all skills related to self-directed learning were identified. Next, an item pool was prepared and administered to 255 students from various…

A Novel Laboratory Activity for Teaching about the Evolution of Multicellularity

ERIC Educational Resources Information Center

Ratcliff, William C.; Raney, Allison; Westreich, Sam; Cotner, Sehoya

2014-01-01

The evolution of complexity remains one of the most challenging topics in biology to teach effectively. We present a novel laboratory activity, modeled on a recent experimental breakthrough, in which students experimentally evolve simple multicellularity using single-celled yeast ("Saccharomyces cerevisiae"). By simply selecting for…

Plug-and-Play Multicellular Circuits with Time-Dependent Dynamic Responses.

PubMed

Urrios, Arturo; Gonzalez-Flo, Eva; Canadell, David; de Nadal, Eulàlia; Macia, Javier; Posas, Francesc

2018-04-20

Synthetic biology studies aim to develop cellular devices for biomedical applications. These devices, based on living instead of electronic or electromechanic technology, might provide alternative treatments for a wide range of diseases. However, the feasibility of these devices depends, in many cases, on complex genetic circuits that must fulfill physiological requirements. In this work, we explored the potential of multicellular architectures to act as an alternative to complex circuits for implementation of new devices. As a proof of concept, we developed specific circuits for insulin or glucagon production in response to different glucose levels. Here, we show that fundamental features, such as circuit's affinity or sensitivity, are dependent on the specific configuration of the multicellular consortia, providing a method for tuning these properties without genetic engineering. As an example, we have designed and built circuits with an incoherent feed-forward loop architecture (FFL) that can be easily adjusted to generate single pulse responses. Our results might serve as a blueprint for future development of cellular devices for glycemia regulation in diabetic patients.

The Self-esteem Stability Scale (SESS) for Cross-Sectional Direct Assessment of Self-esteem Stability

PubMed Central

Altmann, Tobias; Roth, Marcus

2018-01-01

Self-esteem stability describes fluctuations in the level of self-esteem experienced by individuals over a brief period of time. In recent decades, self-esteem stability has repeatedly been shown to be an important variable affecting psychological functioning. However, measures of self-esteem stability are few and lacking in validity. In this paper, we present the Self-Esteem Stability Scale (SESS), a unidimensional and very brief scale to directly assess self-esteem stability. In four studies (total N = 826), we describe the development of the SESS and present evidence for its validity with respect to individual outcomes (life satisfaction, neuroticism, and vulnerable narcissism) and dyadic outcomes (relationship satisfaction in self- and partner ratings) through direct comparisons with existing measures. The new SESS proved to be a stronger predictor than the existing scales and had incremental validity over and above self-esteem level. The results also showed that all cross-sectional measures of self-esteem stability were only moderately associated with variability in self-esteem levels assessed longitudinally with multiple administrations of the Rosenberg Self-Esteem Scale. We discuss this validity issue, arguing that direct and indirect assessment approaches measure relevant, yet different aspects of self-esteem stability. PMID:29487551

The Self-esteem Stability Scale (SESS) for Cross-Sectional Direct Assessment of Self-esteem Stability.

PubMed

Altmann, Tobias; Roth, Marcus

2018-01-01

Self-esteem stability describes fluctuations in the level of self-esteem experienced by individuals over a brief period of time. In recent decades, self-esteem stability has repeatedly been shown to be an important variable affecting psychological functioning. However, measures of self-esteem stability are few and lacking in validity. In this paper, we present the Self-Esteem Stability Scale (SESS), a unidimensional and very brief scale to directly assess self-esteem stability. In four studies (total N = 826), we describe the development of the SESS and present evidence for its validity with respect to individual outcomes (life satisfaction, neuroticism, and vulnerable narcissism) and dyadic outcomes (relationship satisfaction in self- and partner ratings) through direct comparisons with existing measures. The new SESS proved to be a stronger predictor than the existing scales and had incremental validity over and above self-esteem level. The results also showed that all cross-sectional measures of self-esteem stability were only moderately associated with variability in self-esteem levels assessed longitudinally with multiple administrations of the Rosenberg Self-Esteem Scale. We discuss this validity issue, arguing that direct and indirect assessment approaches measure relevant, yet different aspects of self-esteem stability.

Role of Multicellular Aggregates in Biofilm Formation

PubMed Central

Kragh, Kasper N.; Hutchison, Jaime B.; Melaugh, Gavin; Rodesney, Chris; Roberts, Aled E. L.; Irie, Yasuhiko; Jensen, Peter Ø.; Diggle, Stephen P.; Allen, Rosalind J.

2016-01-01

ABSTRACT In traditional models of in vitro biofilm development, individual bacterial cells seed a surface, multiply, and mature into multicellular, three-dimensional structures. Much research has been devoted to elucidating the mechanisms governing the initial attachment of single cells to surfaces. However, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process. This makes it likely that biofilms are often seeded by aggregates and single cells, yet how these aggregates impact biofilm initiation and development is not known. Here we use a combination of experimental and computational approaches to determine the relative fitness of single cells and preformed aggregates during early development of Pseudomonas aeruginosa biofilms. We find that the relative fitness of aggregates depends markedly on the density of surrounding single cells, i.e., the level of competition for growth resources. When competition between aggregates and single cells is low, an aggregate has a growth disadvantage because the aggregate interior has poor access to growth resources. However, if competition is high, aggregates exhibit higher fitness, because extending vertically above the surface gives cells at the top of aggregates better access to growth resources. Other advantages of seeding by aggregates, such as earlier switching to a biofilm-like phenotype and enhanced resilience toward antibiotics and immune response, may add to this ecological benefit. Our findings suggest that current models of biofilm formation should be reconsidered to incorporate the role of aggregates in biofilm initiation. PMID:27006463

Participants' Assessment of the Impact of Behavioral Health Self-Direction on Recovery.

PubMed

Croft, Bevin; Parish, Susan

2016-10-01

Self-direction involves managing a flexible budget, selecting and purchasing services and supports to meet individual needs and preferences. An emerging practice in the behavioral health field, self-direction is part of a systemic shift toward person-centered approaches to service provision. To understand the relationship between recovery and self-direction, the authors conducted a content analysis of 30 in-depth interviews with individuals from two self-direction programs in one state. A positive relationship between self-direction and recovery was established. Meeting basic needs for food, clothing, and shelter are important first steps in the recovery process for self-directing participants. Recovery domains were dynamic and interrelated, with gains in independence, self-esteem, and self-confidence facilitating achievement of goals in other domains. To maximize the benefits of self-direction, program administrators may need to develop clearer program implementation standards and address poverty and limited access to appropriate behavioral health services and supports.

Tumour cells down-regulate CCN2 gene expression in co-cultured fibroblasts in a Smad7- and ERK-dependent manner.

PubMed

van Rooyen, Beverley A; Schäfer, Georgia; Leaner, Virna D; Parker, M Iqbal

2013-10-03

Recent studies have revealed that interactions between tumour cells and the surrounding stroma play an important role in facilitating tumour growth and invasion. Stromal fibroblasts produce most of the extracellular matrix components found in the stroma. The aim of this study was to investigate mechanisms involved in tumour cell-mediated regulation of extracellular matrix and adhesion molecules in co-cultured fibroblasts. To this end, microarray analysis was performed on CCD-1068SK human fibroblast cells after direct co-culture with MDA-MB-231 human breast tumour cells. We found that the expression of both connective tissue growth factor (CTGF/CCN2) and type I collagen was negatively regulated in CCD-1068SK fibroblast cells under direct co-culture conditions. Further analysis revealed that Smad7, a known negative regulator of the Smad signalling pathway involved in CCN2 promoter regulation, was increased in directly co-cultured fibroblasts. Inhibition of Smad7 expression in CCD-1068SK fibroblasts resulted in increased CCN2 expression, while Smad7 overexpression had the opposite effect. Silencing CCN2 gene expression in fibroblasts led, in turn, to a decrease in type I collagen mRNA and protein levels. ERK signalling was also shown to be impaired in CCD-1068SK fibroblasts after direct co-culture with MDA-MB-231 tumour cells, with Smad7 overexpression in fibroblasts leading to a similar decrease in ERK activity. These effects were not, however, seen in fibroblasts that were indirectly co-cultured with tumour cells. We therefore conclude that breast cancer cells require close contact with fibroblasts in order to upregulate Smad7 which, in turn, leads to decreased ERK signalling resulting in diminished expression of the stromal proteins CCN2 and type I collagen.

Kinetic Monte Carlo and cellular particle dynamics simulations of multicellular systems

NASA Astrophysics Data System (ADS)

Flenner, Elijah; Janosi, Lorant; Barz, Bogdan; Neagu, Adrian; Forgacs, Gabor; Kosztin, Ioan

2012-03-01

Computer modeling of multicellular systems has been a valuable tool for interpreting and guiding in vitro experiments relevant to embryonic morphogenesis, tumor growth, angiogenesis and, lately, structure formation following the printing of cell aggregates as bioink particles. Here we formulate two computer simulation methods: (1) a kinetic Monte Carlo (KMC) and (2) a cellular particle dynamics (CPD) method, which are capable of describing and predicting the shape evolution in time of three-dimensional multicellular systems during their biomechanical relaxation. Our work is motivated by the need of developing quantitative methods for optimizing postprinting structure formation in bioprinting-assisted tissue engineering. The KMC and CPD model parameters are determined and calibrated by using an original computational-theoretical-experimental framework applied to the fusion of two spherical cell aggregates. The two methods are used to predict the (1) formation of a toroidal structure through fusion of spherical aggregates and (2) cell sorting within an aggregate formed by two types of cells with different adhesivities.

Fibroblast growth factor 21 has no direct role in regulating fertility in female mice.

PubMed

Singhal, Garima; Douris, Nicholas; Fish, Alan J; Zhang, Xinyao; Adams, Andrew C; Flier, Jeffrey S; Pissios, Pavlos; Maratos-Flier, Eleftheria

2016-08-01

Reproduction is an energetically expensive process. Insufficient calorie reserves, signaled to the brain through peripheral signals such as leptin, suppress fertility. Recently, fibroblast growth factor 21 (FGF21) was implicated as a signal from the liver to the hypothalamus that directly inhibits the hypothalamic-gonadotropin axis during fasting and starvation. However, FGF21 itself increases metabolic rate and can induce weight loss, which suggests that the effects of FGF21 on fertility may not be direct and may reflect changes in energy balance. To address this important question, we evaluated fertility in several mouse models with elevated FGF21 levels including ketogenic diet fed mice, fasted mice, mice treated with exogenous FGF21 and transgenic mice over-expressing FGF21. We find that ketogenic diet fed mice remain fertile despite significant elevation in serum FGF21 levels. Absence of FGF21 does not alter transient infertility induced by fasting. Centrally infused FGF21 does not suppress fertility despite its efficacy in inducing browning of inguinal white adipose tissue. Furthermore, a high fat diet (HFD) can restore fertility of female FGF21-overexpressing mice, a model of growth restriction, even in the presence of supraphysiological serum FGF21 levels. We conclude that FGF21 is not a direct physiological regulator of fertility in mice. The infertility observed in FGF21 overexpressing mice is likely driven by the increased energy expenditure and consequent excess calorie requirements resulting from high FGF21 levels.

Gastrointestinal Fibroblasts Have Specialized, Diverse Transcriptional Phenotypes: A Comprehensive Gene Expression Analysis of Human Fibroblasts

PubMed Central

Ishii, Genichiro; Aoyagi, Kazuhiko; Sasaki, Hiroki; Ochiai, Atsushi

2015-01-01

Background Fibroblasts are the principal stromal cells that exist in whole organs and play vital roles in many biological processes. Although the functional diversity of fibroblasts has been estimated, a comprehensive analysis of fibroblasts from the whole body has not been performed and their transcriptional diversity has not been sufficiently explored. The aim of this study was to elucidate the transcriptional diversity of human fibroblasts within the whole body. Methods Global gene expression analysis was performed on 63 human primary fibroblasts from 13 organs. Of these, 32 fibroblasts from gastrointestinal organs (gastrointestinal fibroblasts: GIFs) were obtained from a pair of 2 anatomical sites: the submucosal layer (submucosal fibroblasts: SMFs) and the subperitoneal layer (subperitoneal fibroblasts: SPFs). Using hierarchical clustering analysis, we elucidated identifiable subgroups of fibroblasts and analyzed the transcriptional character of each subgroup. Results In unsupervised clustering, 2 major clusters that separate GIFs and non-GIFs were observed. Organ- and anatomical site-dependent clusters within GIFs were also observed. The signature genes that discriminated GIFs from non-GIFs, SMFs from SPFs, and the fibroblasts of one organ from another organ consisted of genes associated with transcriptional regulation, signaling ligands, and extracellular matrix remodeling. Conclusions GIFs are characteristic fibroblasts with specific gene expressions from transcriptional regulation, signaling ligands, and extracellular matrix remodeling related genes. In addition, the anatomical site- and organ-dependent diversity of GIFs was also discovered. These features of GIFs contribute to their specific physiological function and homeostatic maintenance, and create a functional diversity of the gastrointestinal tract. PMID:26046848

Understanding the developmental pathways pulmonary fibroblasts may follow during alveolar regeneration.

PubMed

McGowan, Stephen

2017-03-01

Although pulmonary alveolar interstitial fibroblasts are less specialized than their epithelial and endothelial neighbors, they play essential roles during development and in response to lung injury. At birth, they must adapt to the sudden mechanical changes imposed by the onset of respiration and to a higher ambient oxygen concentration. In diseases such as bronchopulmonary dysplasia and interstitial fibrosis, their adaptive responses are overwhelmed leading to compromised gas-exchange function. Thus, although fibroblasts do not directly participate in gas-exchange, they are essential for creating and maintaining an optimal environment at the alveolar epithelial-endothelial interface. This review summarizes new information and concepts about the ontogeny differentiation, and function of alveolar fibroblasts. Alveolar development will be emphasized, because the development of strategies to evoke alveolar repair and regeneration hinges on thoroughly understanding the way that resident fibroblasts populate specific locations in which extracellular matrix must be produced and remodeled. Other recent reviews have described the disruption that diseases cause to the fibroblast niche and so my objective is to illustrate how the unique developmental origins and differentiation pathways could be harnessed favorably to augment certain fibroblast subpopulations and to optimize the conditions for alveolar regeneration.

Enabling complex nanoscale pattern customization using directed self-assembly.

PubMed

Doerk, Gregory S; Cheng, Joy Y; Singh, Gurpreet; Rettner, Charles T; Pitera, Jed W; Balakrishnan, Srinivasan; Arellano, Noel; Sanders, Daniel P

2014-12-16

Block copolymer directed self-assembly is an attractive method to fabricate highly uniform nanoscale features for various technological applications, but the dense periodicity of block copolymer features limits the complexity of the resulting patterns and their potential utility. Therefore, customizability of nanoscale patterns has been a long-standing goal for using directed self-assembly in device fabrication. Here we show that a hybrid organic/inorganic chemical pattern serves as a guiding pattern for self-assembly as well as a self-aligned mask for pattern customization through cotransfer of aligned block copolymer features and an inorganic prepattern. As informed by a phenomenological model, deliberate process engineering is implemented to maintain global alignment of block copolymer features over arbitrarily shaped, 'masking' features incorporated into the chemical patterns. These hybrid chemical patterns with embedded customization information enable deterministic, complex two-dimensional nanoscale pattern customization through directed self-assembly.

Metabolic cooperation between co-cultured lung cancer cells and lung fibroblasts.

PubMed

Koukourakis, Michael I; Kalamida, Dimitra; Mitrakas, Achilleas G; Liousia, Maria; Pouliliou, Stamatia; Sivridis, Efthimios; Giatromanolaki, Alexandra

2017-11-01

Cooperation of cancer cells with stromal cells, such as cancer-associated fibroblasts (CAFs), has been revealed as a mechanism sustaining cancer cell survival and growth. In the current study, we focus on the metabolic interactions of MRC5 lung fibroblasts with lung cancer cells (A549 and H1299) using co-culture experiments and studying changes of the metabolic protein expression profile and of their growth and migration abilities. Using western blotting, confocal microscopy and RT-PCR, we observed that in co-cultures MRC5 respond by upregulating pyruvate dehydrogenase (PDH) and the monocarboxylate transporter MCT1. In contrast, cancer cells increase the expression of glucose transporters (GLUT1), LDH5, PDH kinase and the levels of phosphorylated/inactivated pPDH. H1299 cells growing in the same culture medium with fibroblasts exhibit a 'metastasis-like' phenomenon by forming nests within the fibroblast area. LDH5 and pPDH were drastically upregulated in these nests. The growth rate of both MRC5 and cancer cells increased in co-cultures. Suppression of LDHA or PDK1 in cancer cells abrogates the stimulatory signal from cancer cells to fibroblasts. Incubation of MRC5 fibroblasts with lactate resulted in an increase of LDHB and of PDH expression. Silencing of PDH gene in fibroblasts, or silencing of PDK1 or LDHA gene in tumor cells, impedes cancer cell's migration ability. Overall, a metabolic cooperation between lung cancer cells and fibroblasts has been confirmed in the context of direct Warburg effect, thus the fibroblasts reinforce aerobic metabolism to support the intensified anaerobic glycolytic pathways exploited by cancer cells.

Mechanochemical switching between growth and differentiation during fibroblast growth factor-stimulated angiogenesis in vitro: role of extracellular matrix

PubMed Central

1989-01-01

The angiogenic factor, basic fibroblast growth factor (FGF), either stimulates endothelial cell growth or promotes capillary differentiation depending upon the microenvironment in which it acts. Analysis of various in vitro models of spontaneous angiogenesis, in combination with time-lapse cinematography, demonstrated that capillary tube formation was greatly facilitated by promoting multicellular retraction and cell elevation above the surface of the rigid culture dish or by culturing endothelial cells on malleable extracellular matrix (ECM) substrata. These observations suggested to us that mechanical (i.e., tension-dependent) interactions between endothelial cells and ECM may serve to regulate capillary development. To test this hypothesis, FGF-stimulated endothelial cells were grown in chemically defined medium on bacteriological (nonadhesive) dishes that were precoated with different densities of fibronectin. Extensive cell spreading and growth were promoted by fibronectin coating densities that were highly adhesive (greater than 500 ng/cm2), whereas cell rounding, detachment, and loss of viability were observed on dishes coated with low fibronectin concentrations (less than 100 ng/cm2). Intermediate fibronectin coating densities (100-500 ng/cm2) promoted cell extension, but they could not completely resist cell tractional forces. Partial retraction of multicellular aggregates resulted in cell shortening, cessation of growth, and formation of branching tubular networks within 24-48 h. Multicellular retraction and subsequent tube formation also could be elicited on highly adhesive dishes by overcoming the mechanical resistance of the substratum using higher cell plating numbers. Dishes coated with varying concentrations of type IV collagen or gelatin produced similar results. These results suggest that ECM components may act locally to regulate the growth and pattern- regulating actions of soluble FGF based upon their ability to resist cell-generated mechanical

MiR-191 Regulates Primary Human Fibroblast Proliferation and Directly Targets Multiple Oncogenes

PubMed Central

Polioudakis, Damon; Abell, Nathan S.; Iyer, Vishwanath R.

2015-01-01

miRNAs play a central role in numerous pathologies including multiple cancer types. miR-191 has predominantly been studied as an oncogene, but the role of miR-191 in the proliferation of primary cells is not well characterized, and the miR-191 targetome has not been experimentally profiled. Here we utilized RNA induced silencing complex immunoprecipitations as well as gene expression profiling to construct a genome wide miR-191 target profile. We show that miR-191 represses proliferation in primary human fibroblasts, identify multiple proto-oncogenes as novel miR-191 targets, including CDK9, NOTCH2, and RPS6KA3, and present evidence that miR-191 extensively mediates target expression through coding sequence (CDS) pairing. Our results provide a comprehensive genome wide miR-191 target profile, and demonstrate miR-191’s regulation of primary human fibroblast proliferation. PMID:25992613

Self-Service and E-Education: The Relationship to Self-Directed Learning

NASA Astrophysics Data System (ADS)

Wells, Marilyn A.; Brook, Phillip W. J.

Self-service via the Internet is becoming a common method of selling goods or services as customers have access to retailers’ websites whenever the “need” takes them. Higher education institutions are increasingly offering e-education which means that traditional teaching methods need modifying. Traditional teaching often consists of presenting and expanding upon material found in a prescribed text and delivering this content in lecture, seminar or workshop mode. Studies have confirmed that students learn more effectively when they can discuss the material with others and treat learning as a collaborative process. This chapter reports a case study, where students were required to decide on their level of involvement, discuss and propose the criteria for assessment evaluation, share ideas, concepts and understanding amongst themselves: in effect, self-directed learning. The learning environment used computer-mediated tools, such as discussion forums and chat rooms, and the case study assesses both the expectations of the teaching staff and the experiences of the students, and relates the outcomes to self-directed learning in a self-service environment.

Matrix metalloproteinase-9 activates TGF-β and stimulates fibroblast contraction of collagen gels.

PubMed

Kobayashi, Tetsu; Kim, HuiJung; Liu, Xiangde; Sugiura, Hisatoshi; Kohyama, Tadashi; Fang, Qiuhong; Wen, Fu-Qiang; Abe, Shinji; Wang, Xingqi; Atkinson, Jeffrey J; Shipley, James M; Senior, Robert M; Rennard, Stephen I

2014-06-01

Matrix metalloproteinase-9 (MMP-9) is a matrix-degrading enzyme implicated in many biological processes, including inflammation. It is produced by many cells, including fibroblasts. When cultured in three-dimensional (3D) collagen gels, fibroblasts contract the surrounding matrix, a function that is thought to model the contraction that characterizes both normal wound repair and fibrosis. The current study was designed to evaluate the role of endogenously produced MMP-9 in fibroblast contraction of 3D collagen gels. Fibroblasts from mice lacking expression of MMP-9 and human lung fibroblasts (HFL-1) transfected with MMP-9 small-interfering RNA (siRNA) were used. Fibroblasts were cast into type I collagen gels and floated in culture medium with or without transforming growth factor (TGF)-β1 for 5 days. Gel size was determined daily using an image analysis system. Gels made from MMP-9 siRNA-treated human fibroblasts contracted less than control fibroblasts, as did fibroblasts incubated with a nonspecific MMP inhibitor. Similarly, fibroblasts cultured from MMP-9-deficient mice contracted gels less than did fibroblasts from control mice. Transfection of the MMP-9-deficient murine fibroblasts with a vector expressing murine MMP-9 restored contractile activity to MMP-9-deficient fibroblasts. Inhibition of MMP-9 reduced active TGF-β1 and reduced several TGF-β1-driven responses, including activity of a Smad3 reporter gene and production of fibronectin. Because TGF-β1 also drives fibroblast gel contraction, this suggests the mechanism for MMP-9 regulation of contraction is through the generation of active TGF-β1. This study provides direct evidence that endogenously produced MMP-9 has a role in regulation of tissue contraction of 3D collagen gels mediated by fibroblasts. Copyright © 2014 the American Physiological Society.

The Influence of Complexity and Uncertainty on Self-Directed Team Learning

ERIC Educational Resources Information Center

Gray, David

2012-01-01

To help increase the effectiveness of self-directed teams, this paper studies the attitudes and behaviour of self-directed team members during the course of a computer simulated marketing strategy game. Self-directed teams are used widely throughout organisations yet receive little scrutiny when they undertake a task which is subject to conditions…

Perceptions of Self-Determination by Special Education and Rehabilitation Practitioners Based on Viewing a Self-Directed IEP versus an External-Directed IEP Meeting

ERIC Educational Resources Information Center

Branding, Dave; Bates, Paul; Miner, Craig

2009-01-01

This study investigated perception of self-determination by special education and rehabilitation practitioners following their exposure to a videotaped simulation of a self-directed IEP meeting and an external-directed IEP meeting involving an adolescent with mild mental retardation. Groups of special education practitioners and rehabilitation…

Views of Gifted Elementary Students about Self-Directed Learning

ERIC Educational Resources Information Center

Van Deur, Penny

2011-01-01

Despite the connection between independent learning and gifted students, little is known of the views these students hold about the process of being self-directed learners. This interview study examined views of ten gifted elementary school students in South Australia about Self-Directed Learning. The interview responses showed that these gifted…

Calcium oscillations in wounded fibroblast monolayers are spatially regulated through substrate mechanics

NASA Astrophysics Data System (ADS)

Lembong, Josephine; Sabass, Benedikt; Stone, Howard A.

2017-08-01

The maintenance of tissue integrity is essential for the life of multicellular organisms. Healing of a skin wound is a paradigm for how various cell types localize and repair tissue perturbations in an orchestrated fashion. To investigate biophysical mechanisms associated with wound localization, we focus on a model system consisting of a fibroblast monolayer on an elastic substrate. We find that the creation of an edge in the monolayer causes cytosolic calcium oscillations throughout the monolayer. The oscillation frequency increases with cell density, which shows that wound-induced calcium oscillations occur collectively. Inhibition of myosin II reduces the number of oscillating cells, demonstrating a coupling between actomyosin activity and calcium response. The spatial distribution of oscillating cells depends on the stiffness of the substrate. For soft substrates with a Young’s modulus E ~ 360 Pa, oscillations occur on average within 0.2 mm distance from the wound edge. Increasing substrate stiffness leads to an average localization of oscillations away from the edge (up to ~0.6 mm). In addition, we use traction force microscopy to determine stresses between cells and substrate. We find that an increase of substrate rigidity leads to a higher traction magnitude. For E  <  ~2 kPa, the traction magnitude is strongly concentrated at the monolayer edge, while for E  >  ~8 kPa, traction magnitude is on average almost uniform beneath the monolayer. Thus, the spatial occurrence of calcium oscillations correlates with the cell-substrate traction. Overall, the experiments with fibroblasts demonstrate a collective, chemomechanical localization mechanism at the edge of a wound with a potential physiological role.

Extracellular Matrix and Dermal Fibroblast Function in the Healing Wound

PubMed Central

Tracy, Lauren E.; Minasian, Raquel A.; Caterson, E.J.

2016-01-01

Significance: Fibroblasts play a critical role in normal wound healing. Various extracellular matrix (ECM) components, including collagens, fibrin, fibronectin, proteoglycans, glycosaminoglycans, and matricellular proteins, can be considered potent protagonists of fibroblast survival, migration, and metabolism. Recent Advances: Advances in tissue culture, tissue engineering, and ex vivo models have made the examination and precise measurements of ECM components in wound healing possible. Likewise, the development of specific transgenic animal models has created the opportunity to characterize the role of various ECM molecules in healing wounds. In addition, the recent characterization of new ECM molecules, including matricellular proteins, dermatopontin, and FACIT collagens (Fibril-Associated Collagens with Interrupted Triple helices), further demonstrates our cursory knowledge of the ECM in coordinated wound healing. Critical Issues: The manipulation and augmentation of ECM components in the healing wound is emerging in patient care, as demonstrated by the use of acellular dermal matrices, tissue scaffolds, and wound dressings or topical products bearing ECM proteins such as collagen, hyaluronan (HA), or elastin. Once thought of as neutral structural proteins, these molecules are now known to directly influence many aspects of cellular wound healing. Future Directions: The role that ECM molecules, such as CCN2, osteopontin, and secreted protein, acidic and rich in cysteine, play in signaling homing of fibroblast progenitor cells to sites of injury invites future research as we continue investigating the heterotopic origin of certain populations of fibroblasts in a healing wound. Likewise, research into differently sized fragments of the same polymeric ECM molecule is warranted as we learn that fragments of molecules such as HA and tenascin-C can have opposing effects on dermal fibroblasts. PMID:26989578

External Factors, Internal Factors and Self-Directed Learning Readiness

ERIC Educational Resources Information Center

Ramli, Nurjannah; Muljono, Pudji; Afendi, Farit M.

2018-01-01

There are many factors which affect the level of self-directed learning readiness. This study aims to investigate the relationship between external factors, internal factors and self-directed learning readiness. This study was carried out by using a census method for fourth year students of medical program of Tadulako University. Data were…

Patient-derived multicellular tumor spheroids towards optimized treatment for patients with hepatocellular carcinoma.

PubMed

Song, Yeonhwa; Kim, Jin-Sun; Kim, Se-Hyuk; Park, Yoon Kyung; Yu, Eunsil; Kim, Ki-Hun; Seo, Eul-Ju; Oh, Heung-Bum; Lee, Han Chu; Kim, Kang Mo; Seo, Haeng Ran

2018-05-25

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide and has poor prognosis. Specially, patients with HCC usually have poor tolerance of systemic chemotherapy, because HCCs develop from chronically damaged tissue that contains considerable inflammation, fibrosis, and cirrhosis. Since HCC exhibits highly heterogeneous molecular characteristics, a proper in vitro system is required for the study of HCC pathogenesis. To this end, we have established two new hepatitis B virus (HBV) DNA-secreting HCC cell lines from infected patients. Based on these two new HCC cell lines, we have developed chemosensitivity assays for patient-derived multicellular tumor spheroids (MCTSs) in order to select optimized anti-cancer drugs to provide more informative data for clinical drug application. To monitor the effect of the interaction of cancer cells and stromal cells in MCTS, we used a 3D co-culture model with patient-derived HCC cells and stromal cells from human hepatic stellate cells, human fibroblasts, and human umbilical vein endothelial cells to facilitate screening for optimized cancer therapy. To validate our system, we performed a comparison of chemosensitivity of the three culture systems, which are monolayer culture system, tumor spheroids, and MCTSs of patient-derived cells, to sorafenib, 5-fluorouracil, and cisplatin, as these compounds are typically standard therapy for advanced HCC in South Korea. In summary, these findings suggest that the MCTS culture system is the best methodology for screening for optimized treatment for each patients with HCC, because tumor spheroids not only mirror the 3D cellular context of the tumors but also exhibit therapeutically relevant pathophysiological gradients and heterogeneity of in vivo tumors.

MicroRNA Intercellular Transfer and Bioelectrical Regulation of Model Multicellular Ensembles by the Gap Junction Connectivity.

PubMed

Cervera, Javier; Meseguer, Salvador; Mafe, Salvador

2017-08-17

We have studied theoretically the microRNA (miRNA) intercellular transfer through voltage-gated gap junctions in terms of a biophysically grounded system of coupled differential equations. Instead of modeling a specific system, we use a general approach describing the interplay between the genetic mechanisms and the single-cell electric potentials. The dynamics of the multicellular ensemble are simulated under different conditions including spatially inhomogeneous transcription rates and local intercellular transfer of miRNAs. These processes result in spatiotemporal changes of miRNA, mRNA, and ion channel protein concentrations that eventually modify the bioelectrical states of small multicellular domains because of the ensemble average nature of the electrical potential. The simulations allow a qualitative understanding of the context-dependent nature of the effects observed when specific signaling molecules are transferred through gap junctions. The results suggest that an efficient miRNA intercellular transfer could permit the spatiotemporal control of small cellular domains by the conversion of single-cell genetic and bioelectric states into multicellular states regulated by the gap junction interconnectivity.

Symplasmata are a clonal, conditional, and reversible type of bacterial multicellularity

DOE PAGES

Tecon, Robin; Leveau, Johan H. J.

2016-08-18

Microorganisms are capable of remarkable social behaviours, such as forming transient multicellular assemblages with properties and adaptive abilities exceeding those of individual cells. Here, we report on the formation and structure of genets known as symplasmata produced by Pantoea eucalypti bacteria. Each symplasmatum develops clonally and stochastically from a single bacterium into a membrane-delimited, capsule-embedded cluster of progeny cells and with a frequency that depends on temperature, pH, and nutrient availability. Transposon mutagenesis identified several gene products required for symplasmata formation, including master regulator LrhA, replication inhibitor CspD, polysaccharide transporter RfbX3, and autoinducer synthase PhzI. We also show that bacteriamore » inside symplasmata are shaped irregularly with punctuated cell-to-cell contacts, metabolically responsive to environmental stimuli, dispersal-ready, and transcriptionally reprogrammed to anticipate multiple alternative futures in terms of carbon source availability. In conclusion, the structured and conditionable nature of symplasmata offers exciting prospects towards a mechanistic understanding of multicellular behaviours and their ecological significance.« less

Cellular and multicellular form and function.

PubMed

Liu, Wendy F; Chen, Christopher S

2007-11-10

Engineering artificial tissue constructs requires the appropriate spatial arrangement of cells within scaffolds. The introduction of microengineering tools to the biological community has provided a valuable set of techniques to manipulate the cellular environment, and to examine how cell structure affects cellular function. Using micropatterning techniques, investigators have found that the geometric presentation of cell-matrix adhesions are important regulators of various cell behaviors including cell growth, proliferation, differentiation, polarity and migration. Furthermore, the presence of neighboring cells in multicellular aggregates has a significant impact on the proliferative and differentiated state of cells. Using microengineering tools, it will now be possible to manipulate the various environmental factors for practical applications such as engineering tissue constructs with greater control over the physical structure and spatial arrangement of cells within their surrounding microenvironment.

Self- directed learning barriers in a virtual environment: a qualitative study.

PubMed

Kohan, Noushin; Soltani Arabshahi, Kamran; Mojtahedzadeh, Rita; Abbaszadeh, Abbas; Rakhshani, Tayebeh; Emami, Amirhousein

2017-07-01

There is a growing trend in online education courses in higher education institutes. Previous studies have shown that high levels of self-direction are essential for successful online learning. The present study aims to investigate challenges of and barriers to self-directed virtual-learning among postgraduate students of medical sciences. 23 postgraduate virtual students of medical sciences in Iran, collected through maximum variation purposive sampling and semi-structured interviews, served as the sample of this study. The collected data were analyzed using the inductive content analysis method. Three themes and six sub-themes were identified as barriers to self-directed learning in virtual education, including cognitive barriers (information overload and lack of focus on learning or mind wondering), communication barriers (inadequate coping skills and inadequate writing skills) and educational environment barriers (heavy workload and role ambiguity). By the importance of self-direction in online education, the present study results can be used by virtual education planners in the review and design of courses, so as to adequately equip students, obviate barriers to self-directed virtual education, and ultimately train highly self-directed learners in online medical education.

Self- directed learning barriers in a virtual environment: a qualitative study

PubMed Central

KOHAN, NOUSHIN; SOLTANI ARABSHAHI, KAMRAN; MOJTAHEDZADEH, RITA; ABBASZADEH, ABBAS; RAKHSHANI, TAYEBEH; EMAMI, AMIRHOUSEIN

2017-01-01

Introduction: There is a growing trend in online education courses in higher education institutes. Previous studies have shown that high levels of self-direction are essential for successful online learning. The present study aims to investigate challenges of and barriers to self-directed virtual-learning among postgraduate students of medical sciences. Method: 23 postgraduate virtual students of medical sciences in Iran, collected through maximum variation purposive sampling and semi-structured interviews, served as the sample of this study. The collected data were analyzed using the inductive content analysis method. Results: Three themes and six sub-themes were identified as barriers to self-directed learning in virtual education, including cognitive barriers (information overload and lack of focus on learning or mind wondering), communication barriers (inadequate coping skills and inadequate writing skills) and educational environment barriers (heavy workload and role ambiguity). Conclusion: By the importance of self-direction in online education, the present study results can be used by virtual education planners in the review and design of courses, so as to adequately equip students, obviate barriers to self-directed virtual education, and ultimately train highly self-directed learners in online medical education. PMID:28761885

Self-Punishment Promotes Forgiveness in the Direct and Indirect Reciprocity Contexts.

PubMed

Zhu, Ruida; Shen, Xueyi; Tang, Honghong; Ye, Peixia; Wang, Huagen; Mai, Xiaoqin; Liu, Chao

2017-06-01

Most previous studies regarding self-punishment have focused on the correlation between moral emotion and self-punishment. Only a few studies have attempted to understand self-punishment from the perspective of seeking forgiveness, and no study has yet directly tested whether wrongdoers' self-punishment promotes others to forgive the wrongdoers. In three studies, the participants judged the wrongdoers' self-punishment behaviors following an unfair allocation and reported the extent to which they forgave the wrongdoers. The results demonstrated that self-punishment did promote forgiveness in both the direct (Studies 1 and 2) and indirect reciprocity (Study 3) contexts. Consistent with costly signaling theory, the costlier the self-punishment was, the stronger the effect it had on forgiveness. Moreover, communicative self-punishment had a better effect than silent self-punishment when the cost was relatively high in the direct-reciprocity studies. These findings can guide us regarding how to address a damaged relationship via self-punishment when compensation is not feasible or acceptable.

Analysis of self-directed mastery learning of honors physics

NASA Astrophysics Data System (ADS)

Athens, Wendy

Self-directed learning (SDL) is an important life skill in a knowledge-based society and prepares students to persist, manage their time and resources, use logic to construct their knowledge, argue their views, and collaborate. The purpose of this study was to facilitate mastery of physics concepts through self-directedness in formative testing with feedback, a choice of learning activities, and multiple forms of support. This study was conducted within two sections of honors physics at a private high school (N=24). Students' learning activity choices, time investments, and perceptions (assessed through a post survey) were tracked and analyzed. SDL readiness was linked to success in mastering physics concepts. The three research questions pursued in this study were: What SDL activities did honors physics students choose in their self-directed mastery learning environment? How many students achieved concept mastery and how did they spend their time? Did successful and unsuccessful students perceive the self-directed mastery learning environment differently? Only seven of 24 students were successful in passing the similar concept-based unit tests within four tries, and these seven students were separated into a "successful" group and the other 17 into an "unsuccessful" group. Differences between the two groups were analyzed. A profile of a self-directed secondary honors physics student emerged. A successful self-directed student invested more time learning from activities rather than simply completing them, focused on learning concepts more than rote operations, intentionally selected activities to fill in gaps of knowledge and practice concepts, actively constructed knowledge into a cognitive framework, engaged in academic discourse with instructor and peers as they made repeated attempts to master content and pass the test given constructive feedback, used a wide variety of learning resources, and managed their workload to meet deadlines. This capstone study found

Founders' Continuing Roles in Schools Supporting Self-Directed Learning

ERIC Educational Resources Information Center

Nash, Carol

2014-01-01

What should be the continuing role of founders in schools supporting self-directed learning? To answer this, the founders' views of two North American schools for self-directed learners will be compared. One school is exam-focused and private; the other is, test-free and public. The founders of both schools have comparable beliefs regarding the…

The Role of Cell-Cell Adhesion in the Formation of Multicellular Sprouts

PubMed Central

Szabó, A.; Czirók, A.

2010-01-01

Collective cell motility and its guidance via cell-cell contacts is instrumental in several morphogenetic and pathological processes such as vasculogenesis or tumor growth. Multicellular sprout elongation, one of the simplest cases of collective motility, depends on a continuous supply of cells streaming along the sprout towards its tip. The phenomenon is often explained as leader cells pulling the rest of the sprout forward via cell-cell adhesion. Building on an empirically demonstrated analogy between surface tension and cell-cell adhesion, we demonstrate that such a mechanism is unable to recruit cells to the sprout. Moreover, the expansion of such hypothetical sprouts is limited by a form of the Plateau-Taylor instability. In contrast, actively moving cells – guided by cell-cell contacts – can readily populate and expand linear sprouts. We argue that preferential attraction to the surfaces of elongated cells can provide a generic mechanism, shared by several cell types, for multicellular sprout formation. PMID:20165554

Predictive modeling of multicellular structure formation by using Cellular Particle Dynamics simulations

NASA Astrophysics Data System (ADS)

McCune, Matthew; Shafiee, Ashkan; Forgacs, Gabor; Kosztin, Ioan

2014-03-01

Cellular Particle Dynamics (CPD) is an effective computational method for describing and predicting the time evolution of biomechanical relaxation processes of multicellular systems. A typical example is the fusion of spheroidal bioink particles during post bioprinting structure formation. In CPD cells are modeled as an ensemble of cellular particles (CPs) that interact via short-range contact interactions, characterized by an attractive (adhesive interaction) and a repulsive (excluded volume interaction) component. The time evolution of the spatial conformation of the multicellular system is determined by following the trajectories of all CPs through integration of their equations of motion. CPD was successfully applied to describe and predict the fusion of 3D tissue construct involving identical spherical aggregates. Here, we demonstrate that CPD can also predict tissue formation involving uneven spherical aggregates whose volumes decrease during the fusion process. Work supported by NSF [PHY-0957914]. Computer time provided by the University of Missouri Bioinformatics Consortium.

Cellular Dysfunction in the Diabetic Fibroblast

PubMed Central

Lerman, Oren Z.; Galiano, Robert D.; Armour, Mary; Levine, Jamie P.; Gurtner, Geoffrey C.

2003-01-01

Although it is known that systemic diseases such as diabetes result in impaired wound healing, the mechanism for this impairment is not understood. Because fibroblasts are essential for wound repair, we compared the in vitro behavior of fibroblasts cultured from diabetic, leptin receptor-deficient (db/db) mice with wild-type fibroblasts from mice of the same genetic background in processes important during tissue repair. Adult diabetic mouse fibroblast migration exhibited a 75% reduction in migration compared to normal fibroblasts (P < 0.001) and was not significantly stimulated by hypoxia (1% O2), whereas wild-type fibroblast migration was up-regulated nearly twofold in hypoxic conditions (P < 0.05). Diabetic fibroblasts produced twice the amount of pro-matrix metalloproteinase-9 as normal fibroblasts, as measured by both gelatin zymography and enzyme-linked immunosorbent assay (P < 0.05). Adult diabetic fibroblasts exhibited a sevenfold impairment in vascular endothelial growth factor (VEGF) production (4.5 ± 1.3 pg/ml versus 34.8 ± 3.3 pg/ml, P < 0.001) compared to wild-type fibroblasts. Moreover, wild-type fibroblast production of VEGF increased threefold in response to hypoxia, whereas diabetic fibroblast production of VEGF was not up-regulated in hypoxic conditions (P < 0.001). To address the question whether these differences resulted from chronic hyperglycemia or absence of the leptin receptor, fibroblasts were harvested from newborn db/db mice before the onset of diabetes (4 to 5 weeks old). These fibroblasts showed no impairments in VEGF production under basal or hypoxic conditions, confirming that the results from db/db fibroblasts in mature mice resulted from the diabetic state and were not because of alterations in the leptin-leptin receptor axis. Markers of cellular viability including proliferation and senescence were not significantly different between diabetic and wild-type fibroblasts. We conclude that, in vitro, diabetic fibroblasts show

Fibroblast heterogeneity: implications for human disease.

PubMed

Lynch, Magnus D; Watt, Fiona M

2018-01-02

Fibroblasts synthesize the extracellular matrix of connective tissue and play an essential role in maintaining the structural integrity of most tissues. Researchers have long suspected that fibroblasts exhibit functional specialization according to their organ of origin, body site, and spatial location. In recent years, a number of approaches have revealed the existence of fibroblast subtypes in mice. Here, we discuss fibroblast heterogeneity with a focus on the mammalian dermis, which has proven an accessible and tractable system for the dissection of these relationships. We begin by considering differences in fibroblast identity according to anatomical site of origin. Subsequently, we discuss new results relating to the existence of multiple fibroblast subtypes within the mouse dermis. We consider the developmental origin of fibroblasts and how this influences heterogeneity and lineage restriction. We discuss the mechanisms by which fibroblast heterogeneity arises, including intrinsic specification by transcriptional regulatory networks and epigenetic factors in combination with extrinsic effects of the spatial context within tissue. Finally, we discuss how fibroblast heterogeneity may provide insights into pathological states including wound healing, fibrotic diseases, and aging. Our evolving understanding suggests that ex vivo expansion or in vivo inhibition of specific fibroblast subtypes may have important therapeutic applications.

T lymphocyte mediated lysis of mitomycin C treated Tenon’s capsule fibroblasts

PubMed Central

Crowston, J G; Chang, L H; Daniels, J T; Khaw, P T; Akbar, A N

2004-01-01

Aims: To evaluate the effect of T cell co-culture on mitomycin C treated and untreated Tenon’s capsule fibroblasts. Methods: IL-2 dependent allogeneic T cells were incubated over a monolayer of mitomycin C treated or control fibroblasts. Fibroblast numbers were evaluated by direct counts using phase contrast microscopy. To determine whether T cell mediated lysis was a consequence of MHC mismatch, co-culture experiments were repeated with autologous T cells. The effect of Fas receptor blockade was established by co-incubation with a Fas blocking (M3) antibody. Results: T cell co-culture resulted in a dramatic reduction in fibroblast survival compared to mitomycin C treatment alone (p = 0.032). T cell killing required fibroblast/lymphocyte cell to cell contact and was observed in both allogeneic and autologous co-culture experiments. Fas blocking antibodies did not significantly inhibit T cell killing (p = 0.39). Conclusion: T cells augment mitomycin C treated fibroblast death in vitro. Similar mechanisms may contribute to the cytotoxic effect of mitomycin C in vivo and account for the largely hypocellular drainage blebs that are observed clinically. PMID:14977777

Asymmetrical Macromolecular Complex Formation of Lysophosphatidic Acid Receptor 2 (LPA2) Mediates Gradient Sensing in Fibroblasts*

PubMed Central

Ren, Aixia; Moon, Changsuk; Zhang, Weiqiang; Sinha, Chandrima; Yarlagadda, Sunitha; Arora, Kavisha; Wang, Xusheng; Yue, Junming; Parthasarathi, Kaushik; Heil-Chapdelaine, Rick; Tigyi, Gabor; Naren, Anjaparavanda P.

2014-01-01

Chemotactic migration of fibroblasts toward growth factors relies on their capacity to sense minute extracellular gradients and respond to spatially confined receptor-mediated signals. Currently, mechanisms underlying the gradient sensing of fibroblasts remain poorly understood. Using single-particle tracking methodology, we determined that a lysophosphatidic acid (LPA) gradient induces a spatiotemporally restricted decrease in the mobility of LPA receptor 2 (LPA2) on chemotactic fibroblasts. The onset of decreased LPA2 mobility correlates to the spatial recruitment and coupling to LPA2-interacting proteins that anchor the complex to the cytoskeleton. These localized PDZ motif-mediated macromolecular complexes of LPA2 trigger a Ca2+ puff gradient that governs gradient sensing and directional migration in response to LPA. Disruption of the PDZ motif-mediated assembly of the macromolecular complex of LPA2 disorganizes the gradient of Ca2+ puffs, disrupts gradient sensing, and reduces the directional migration of fibroblasts toward LPA. Our findings illustrate that the asymmetric macromolecular complex formation of chemoattractant receptors mediates gradient sensing and provides a new mechanistic basis for models to describe gradient sensing of fibroblasts. PMID:25542932

The Effects of Case-Based Team Learning on Students’ Learning, Self Regulation and Self Direction

PubMed Central

Rezaee, Rita; Mosalanejad, Leili

2015-01-01

Introduction: The application of the best approaches to teach adults in medical education is important in the process of training learners to become and remain effective health care providers. This research aims at designing and integrating two approaches, namely team teaching and case study and tries to examine the consequences of these approaches on learning, self regulation and self direction of nursing students. Material & Methods: This is aquasi experimental study of 40 students who were taking a course on mental health. The lessons were designed by using two educational techniques: short case based study and team based learning. Data gathering was based on two valid and reliablequestionnaires: Self-Directed Readiness Scale (SDLRS) and the self-regulating questionnaire. Open ended questions were also designed for the evaluation of students’with points of view on educational methods. Results: The Results showed an increase in the students’ self directed learning based on their performance on the post-test. The results showed that the students’ self-directed learning increased after the intervention. The mean difference before and after intervention self management was statistically significant (p=0.0001). Also, self-regulated learning increased with the mean difference after intervention (p=0.001). Other results suggested that case based team learning can have significant effects on increasing students’ learning (p=0.003). Conclusion: This article may be of value to medical educators who wish to replace traditional learning with informal learning (student-centered-active learning), so as to enhance not only the students’ ’knowledge, but also the advancement of long- life learning skills. PMID:25946918

Methyl-CpG-binding protein 2 mediates antifibrotic effects in scleroderma fibroblasts.

PubMed

He, Ye; Tsou, Pei-Suen; Khanna, Dinesh; Sawalha, Amr H

2018-05-14

Emerging evidence supports a role for epigenetic regulation in the pathogenesis of scleroderma (SSc). We aimed to assess the role of methyl-CpG-binding protein 2 (MeCP2), a key epigenetic regulator, in fibroblast activation and fibrosis in SSc. Dermal fibroblasts were isolated from patients with diffuse cutaneous SSc (dcSSc) and from healthy controls. MeCP2 expression was measured by qPCR and western blot. Myofibroblast differentiation was evaluated by gel contraction assay in vitro. Fibroblast proliferation was analysed by ki67 immunofluorescence staining. A wound healing assay in vitro was used to determine fibroblast migration rates. RNA-seq was performed with and without MeCP2 knockdown in dcSSc to identify MeCP2-regulated genes. The expression of MeCP2 and its targets were modulated by siRNA or plasmid. Chromatin immunoprecipitation followed by sequencing (ChIP-seq) using anti-MeCP2 antibody was performed to assess MeCP2 binding sites within MeCP2-regulated genes. Elevated expression of MeCP2 was detected in dcSSc fibroblasts compared with normal fibroblasts. Overexpressing MeCP2 in normal fibroblasts suppressed myofibroblast differentiation, fibroblast proliferation and fibroblast migration. RNA-seq in MeCP2-deficient dcSSc fibroblasts identified MeCP2-regulated genes involved in fibrosis, including PLAU , NID2 and ADA . Plasminogen activator urokinase (PLAU) overexpression in dcSSc fibroblasts reduced myofibroblast differentiation and fibroblast migration, while nidogen-2 (NID2) knockdown promoted myofibroblast differentiation and fibroblast migration. Adenosine deaminase (ADA) depletion in dcSSc fibroblasts inhibited cell migration rates. Taken together, antifibrotic effects of MeCP2 were mediated, at least partly, through modulating PLAU, NID2 and ADA. ChIP-seq further showed that MeCP2 directly binds regulatory sequences in NID2 and PLAU gene loci. This study demonstrates a novel role for MeCP2 in skin fibrosis and identifies MeCP2-regulated genes

Correcting Nasojugal Groove with Autologous Cultured Fibroblast Injection: A Pilot Study.

PubMed

Moon, Kyung-Chul; Lee, Hyun-Su; Han, Seung-Kyu; Chung, Ho-Yun

2018-06-01

A new commercial drug that contains autologous cultured fibroblasts has been developed and approved by the United States Food and Drug Administration for improving the appearance of nasolabial folds. However, the treatment requires three sessions every 3-6 weeks. It is known that the skin overlying the nasojugal groove is thinner, and the wrinkle is generally shallower than nasolabial folds. Therefore, we hypothesized that the nasojugal groove could be improved by just one treatment session. Therefore, the purpose of this study was to evaluate the efficacy and safety of autologous cultured fibroblast injection to correct nasojugal grooves. Forty-six subjects with nasojugal grooves were enrolled in this study. They were injected with autologous cultured fibroblasts or placebo in one session. Blinded evaluators and subjects assessed the efficacy using a validated wrinkle assessment scale at 4, 12, and 24 weeks after the injection. Information of adverse events was collected at each visit. Based on the evaluators' assessment at 24 weeks after the injection, 76% of subjects treated with autologous cultured fibroblasts showed improvement whereas 0% of subjects treated with placebo showed improvement (P < 0.0001). Based on self-assessment at 24 weeks after the injection, 72% of subjects treated with autologous cultured fibroblasts and 45% of subjects treated with placebo showed improvement (P = 0.0662). There were no serious adverse events related to autologous cultured fibroblast injection. Autologous cultured fibroblast injection might be effective and safe to correct nasojugal grooves. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Separation of cell survival, growth, migration, and mesenchymal transdifferentiation effects of fibroblast secretome on tumor cells of head and neck squamous cell carcinoma.

PubMed

Metzler, Veronika Maria; Pritz, Christian; Riml, Anna; Romani, Angela; Tuertscher, Raphaela; Steinbichler, Teresa; Dejaco, Daniel; Riechelmann, Herbert; Dudás, József

2017-11-01

Fibroblasts play a central role in tumor invasion, recurrence, and metastasis in head and neck squamous cell carcinoma. The aim of this study was to investigate the influence of tumor cell self-produced factors and paracrine fibroblast-secreted factors in comparison to indirect co-culture on cancer cell survival, growth, migration, and epithelial-mesenchymal transition using the cell lines SCC-25 and human gingival fibroblasts. Thereby, we particularly focused on the participation of the fibroblast-secreted transforming growth factor beta-1.Tumor cell self-produced factors were sufficient to ensure tumor cell survival and basic cell growth, but fibroblast-secreted paracrine factors significantly increased cell proliferation, migration, and epithelial-mesenchymal transition-related phenotype changes in tumor cells. Transforming growth factor beta-1 generated individually migrating disseminating tumor cell groups or single cells separated from the tumor cell nest, which were characterized by reduced E-cadherin expression. At the same time, transforming growth factor beta-1 inhibited tumor cell proliferation under serum-starved conditions. Neutralizing transforming growth factor beta antibody reduced the cell migration support of fibroblast-conditioned medium. Transforming growth factor beta-1 as a single factor was sufficient for generation of disseminating tumor cells from epithelial tumor cell nests, while other fibroblast paracrine factors supported tumor nest outgrowth. Different fibroblast-released factors might support tumor cell proliferation and invasion, as two separate effects.

Cell Motility Dynamics: A Novel Segmentation Algorithm to Quantify Multi-Cellular Bright Field Microscopy Images

PubMed Central

Zaritsky, Assaf; Natan, Sari; Horev, Judith; Hecht, Inbal; Wolf, Lior; Ben-Jacob, Eshel; Tsarfaty, Ilan

2011-01-01

Confocal microscopy analysis of fluorescence and morphology is becoming the standard tool in cell biology and molecular imaging. Accurate quantification algorithms are required to enhance the understanding of different biological phenomena. We present a novel approach based on image-segmentation of multi-cellular regions in bright field images demonstrating enhanced quantitative analyses and better understanding of cell motility. We present MultiCellSeg, a segmentation algorithm to separate between multi-cellular and background regions for bright field images, which is based on classification of local patches within an image: a cascade of Support Vector Machines (SVMs) is applied using basic image features. Post processing includes additional classification and graph-cut segmentation to reclassify erroneous regions and refine the segmentation. This approach leads to a parameter-free and robust algorithm. Comparison to an alternative algorithm on wound healing assay images demonstrates its superiority. The proposed approach was used to evaluate common cell migration models such as wound healing and scatter assay. It was applied to quantify the acceleration effect of Hepatocyte growth factor/scatter factor (HGF/SF) on healing rate in a time lapse confocal microscopy wound healing assay and demonstrated that the healing rate is linear in both treated and untreated cells, and that HGF/SF accelerates the healing rate by approximately two-fold. A novel fully automated, accurate, zero-parameters method to classify and score scatter-assay images was developed and demonstrated that multi-cellular texture is an excellent descriptor to measure HGF/SF-induced cell scattering. We show that exploitation of textural information from differential interference contrast (DIC) images on the multi-cellular level can prove beneficial for the analyses of wound healing and scatter assays. The proposed approach is generic and can be used alone or alongside traditional fluorescence single

Cell motility dynamics: a novel segmentation algorithm to quantify multi-cellular bright field microscopy images.

PubMed

Zaritsky, Assaf; Natan, Sari; Horev, Judith; Hecht, Inbal; Wolf, Lior; Ben-Jacob, Eshel; Tsarfaty, Ilan

2011-01-01

Confocal microscopy analysis of fluorescence and morphology is becoming the standard tool in cell biology and molecular imaging. Accurate quantification algorithms are required to enhance the understanding of different biological phenomena. We present a novel approach based on image-segmentation of multi-cellular regions in bright field images demonstrating enhanced quantitative analyses and better understanding of cell motility. We present MultiCellSeg, a segmentation algorithm to separate between multi-cellular and background regions for bright field images, which is based on classification of local patches within an image: a cascade of Support Vector Machines (SVMs) is applied using basic image features. Post processing includes additional classification and graph-cut segmentation to reclassify erroneous regions and refine the segmentation. This approach leads to a parameter-free and robust algorithm. Comparison to an alternative algorithm on wound healing assay images demonstrates its superiority. The proposed approach was used to evaluate common cell migration models such as wound healing and scatter assay. It was applied to quantify the acceleration effect of Hepatocyte growth factor/scatter factor (HGF/SF) on healing rate in a time lapse confocal microscopy wound healing assay and demonstrated that the healing rate is linear in both treated and untreated cells, and that HGF/SF accelerates the healing rate by approximately two-fold. A novel fully automated, accurate, zero-parameters method to classify and score scatter-assay images was developed and demonstrated that multi-cellular texture is an excellent descriptor to measure HGF/SF-induced cell scattering. We show that exploitation of textural information from differential interference contrast (DIC) images on the multi-cellular level can prove beneficial for the analyses of wound healing and scatter assays. The proposed approach is generic and can be used alone or alongside traditional fluorescence single

The Locomotion of Mouse Fibroblasts in Tissue Culture

PubMed Central

Gail, Mitchell H.; Boone, Charles W.

1970-01-01

Time-lapse cinematography was used to investigate the motion of mouse fibroblasts in tissue culture. Observations over successive short time intervals revealed a tendency for the cells to persist in their direction of motion from one 2.5 hr time interval to the next. Over 5.0-hr time intervals, however, the direction of motion appeared random. This fact suggested that D, the diffusion constant of a random walk model, might serve to characterize cellular motility if suitably long observation times were used. We therefore investigated the effect of “persistence” on the pure random walk model, and we found theoretically and confirmed experimentally that the motility of a persisting cell could indeed be characterized by an augmented diffusion constant, D*. A method for determining confidence limits on D* was also developed. Thus a random walk model, modified to comprehend the persistence effect, was found to describe the motion of fibroblasts in tissue culture and to provide a numerical measure of cellular motility. PMID:5531614

PAI1 mediates fibroblast-mast cell interactions in skin fibrosis.

PubMed

Pincha, Neha; Hajam, Edries Yousaf; Badarinath, Krithika; Batta, Surya Prakash Rao; Masudi, Tafheem; Dey, Rakesh; Andreasen, Peter; Kawakami, Toshiaki; Samuel, Rekha; George, Renu; Danda, Debashish; Jacob, Paul Mazhuvanchary; Jamora, Colin

2018-05-01

Fibrosis is a prevalent pathological condition arising from the chronic activation of fibroblasts. This activation results from the extensive intercellular crosstalk mediated by both soluble factors and direct cell-cell connections. Prominent among these are the interactions of fibroblasts with immune cells, in which the fibroblast-mast cell connection, although acknowledged, is relatively unexplored. We have used a Tg mouse model of skin fibrosis, based on expression of the transcription factor Snail in the epidermis, to probe the mechanisms regulating mast cell activity and the contribution of these cells to this pathology. We have discovered that Snail-expressing keratinocytes secrete plasminogen activator inhibitor type 1 (PAI1), which functions as a chemotactic factor to increase mast cell infiltration into the skin. Moreover, we have determined that PAI1 upregulates intercellular adhesion molecule type 1 (ICAM1) expression on dermal fibroblasts, rendering them competent to bind to mast cells. This heterotypic cell-cell adhesion, also observed in the skin fibrotic disorder scleroderma, culminates in the reciprocal activation of both mast cells and fibroblasts, leading to the cascade of events that promote fibrogenesis. Thus, we have identified roles for PAI1 in the multifactorial program of fibrogenesis that expand its functional repertoire beyond its canonical role in plasmin-dependent processes.

Fibroblasts Influence Survival and Therapeutic Response in a 3D Co-Culture Model

PubMed Central

Majety, Meher; Pradel, Leon P.; Gies, Manuela; Ries, Carola H.

2015-01-01

In recent years, evidence has indicated that the tumor microenvironment (TME) plays a significant role in tumor progression. Fibroblasts represent an abundant cell population in the TME and produce several growth factors and cytokines. Fibroblasts generate a suitable niche for tumor cell survival and metastasis under the influence of interactions between fibroblasts and tumor cells. Investigating these interactions requires suitable experimental systems to understand the cross-talk involved. Most in vitro experimental systems use 2D cell culture and trans-well assays to study these interactions even though these paradigms poorly represent the tumor, in which direct cell-cell contacts in 3D spaces naturally occur. Investigating these interactions in vivo is of limited value due to problems regarding the challenges caused by the species-specificity of many molecules. Thus, it is essential to use in vitro models in which human fibroblasts are co-cultured with tumor cells to understand their interactions. Here, we developed a 3D co-culture model that enables direct cell-cell contacts between pancreatic, breast and or lung tumor cells and human fibroblasts/ or tumor-associated fibroblasts (TAFs). We found that co-culturing with fibroblasts/TAFs increases the proliferation in of several types of cancer cells. We also observed that co-culture induces differential expression of soluble factors in a cancer type-specific manner. Treatment with blocking antibodies against selected factors or their receptors resulted in the inhibition of cancer cell proliferation in the co-cultures. Using our co-culture model, we further revealed that TAFs can influence the response to therapeutic agents in vitro. We suggest that this model can be reliably used as a tool to investigate the interactions between a tumor and the TME. PMID:26053043

Respiration control of multicellularity in Bacillus subtilis by a complex of the cytochrome chain with a membrane-embedded histidine kinase

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

Kolodkin-Gal, I; Elsholz, AKW; Muth, C

2013-04-29

Bacillus subtilis forms organized multicellular communities known as biofilms wherein the individual cells are held together by a self-produced extracellular matrix. The environmental signals that promote matrix synthesis remain largely unknown. We discovered that one such signal is impaired respiration. Specifically, high oxygen levels suppressed synthesis of the extracellular matrix. In contrast, low oxygen levels, in the absence of an alternative electron acceptor, led to increased matrix production. The response to impaired respiration was blocked in a mutant lacking cytochromes caa(3) and bc and markedly reduced in a mutant lacking kinase KinB. Mass spectrometry of proteins associated with KinB showedmore » that the kinase was in a complex with multiple components of the aerobic respiratory chain. We propose that KinB is activated via a redox switch involving interaction of its second transmembrane segment with one or more cytochromes under conditions of reduced electron transport. In addition, a second kinase (KinA) contributes to the response to impaired respiration. Evidence suggests that KinA is activated by a decrease in the nicotinamide adenine dinucleotide (NAD(+))/NADH ratio via binding of NAD(+) to the kinase in a PAS domain A-dependent manner. Thus, B. subtilis switches from a unicellular to a multicellular state by two pathways that independently respond to conditions of impaired respiration.« less

Respiration control of multicellularity in Bacillus subtilis by a complex of the cytochrome chain with a membrane-embedded histidine kinase

PubMed Central

Kolodkin-Gal, Ilana; Elsholz, Alexander K.W.; Muth, Christine; Girguis, Peter R.; Kolter, Roberto; Losick, Richard

2013-01-01

Bacillus subtilis forms organized multicellular communities known as biofilms wherein the individual cells are held together by a self-produced extracellular matrix. The environmental signals that promote matrix synthesis remain largely unknown. We discovered that one such signal is impaired respiration. Specifically, high oxygen levels suppressed synthesis of the extracellular matrix. In contrast, low oxygen levels, in the absence of an alternative electron acceptor, led to increased matrix production. The response to impaired respiration was blocked in a mutant lacking cytochromes caa3 and bc and markedly reduced in a mutant lacking kinase KinB. Mass spectrometry of proteins associated with KinB showed that the kinase was in a complex with multiple components of the aerobic respiratory chain. We propose that KinB is activated via a redox switch involving interaction of its second transmembrane segment with one or more cytochromes under conditions of reduced electron transport. In addition, a second kinase (KinA) contributes to the response to impaired respiration. Evidence suggests that KinA is activated by a decrease in the nicotinamide adenine dinucleotide (NAD+)/NADH ratio via binding of NAD+ to the kinase in a PAS domain A-dependent manner. Thus, B. subtilis switches from a unicellular to a multicellular state by two pathways that independently respond to conditions of impaired respiration. PMID:23599347

The influence of mineral particles on fibroblast behaviour: A comparative study.

PubMed

Soto Veliz, Diosangeles; Luoto, Jens C; Pulli, Ilari; Toivakka, Martti

2018-07-01

Minerals are versatile tools utilised to modify and control the physical-chemical and functional properties of substrates. Those properties include ones directing cell fate; thus, minerals can potentially provide a direct and inexpensive method to manipulate cell behaviour. This paper shows how different minerals influence human dermal fibroblast behaviour depending on their properties. Different calcium carbonates, calcium sulphates, silica, silicates, and titanium dioxide were characterised using TEM, ATR-FTIR, and zeta potential measurements. Mineral-cell interactions were analysed through MTT assay, LDH assay, calcein AM staining, live cell imaging, immunofluorescence staining, western blot, and extra/intracellular calcium measurements. Results show that the interaction of the fibroblasts with the minerals was governed by a shared period of adaptation, followed by increased proliferation, growth inhibition, or increased toxicity. Properties such as size, ion release and chemical composition had a direct influence on the cells leading to cell agglomeration, morphological changes, and the possible formation of protein-mineral complexes. In addition, zeta potential and FTIR measurements of the minerals showed adsorption of the cell culture media onto the particles. This article provides fundamental insight into the mineral-fibroblast interactions, and makes it possible to arrange the minerals according to the time-dependent cellular response. Copyright © 2018 Elsevier B.V. All rights reserved.

In vivo reprogramming of murine cardiac fibroblasts into induced cardiomyocytes

PubMed Central

Qian, Li; Huang, Yu; Spencer, C. Ian; Foley, Amy; Vedantham, Vasanth; Liu, Lei; Conway, Simon J.; Fu, Ji-dong; Srivastava, Deepak

2012-01-01

SUMMARY The reprogramming of adult cells into pluripotent cells or directly into alternative adult cell types holds great promise for regenerative medicine. We reported that cardiac fibroblasts, which represent 50% of the cells in the mammalian heart, can be directly reprogrammed to adult cardiomyocyte-like cells in vitro by the addition of Gata4, Mef2c and Tbx5 (GMT). Here, we use genetic lineage-tracing to show that resident non-myocytes in the murine heart can be reprogrammed into cardiomyocyte-like cells in vivo by local delivery of GMT after coronary ligation. Induced cardiomyocytes became bi-nucleate, assembled sarcomeres and had cardiomyocyte-like gene expression. Analysis of single cells revealed ventricular cardiomyocyte-like action potentials, beating upon electrical stimulation, and evidence of electrical coupling. In vivo delivery of GMT decreased infarct size and modestly attenuated cardiac dysfunction up to 3 months after coronary ligation. Delivery of the pro-angiogenic and fibroblast activating peptide, Thymosin β4, along with GMT, resulted in further improvements in scar area and cardiac function. These findings demonstrate that cardiac fibroblasts can be reprogrammed into cardiomyocyte-like cells in their native environment for potential regenerative purposes. PMID:22522929

Non-human Primate and Rat Cardiac Fibroblasts show similar Extracellular Matrix-related and Cellular Adhesion Gene Responses to Substance P

PubMed Central

Meléndez, Giselle C.; Manteufel, Edward J.; Dehlin, Heather M.; Register, Thomas C.; Levick, Scott P.

2015-01-01

Background The sensory nerve neuropeptide substance P (SP) regulates cardiac fibrosis in rodents under pressure overload conditions. Interestingly, SP induces transient increase expression of specific genes in isolated rat cardiac fibroblasts, without resultant changes in cell function. This suggests that SP ‘primes’ fibroblasts, but does not directly activate them. We investigated whether these unusual findings are specific to rodent fibroblasts or are translatable to a larger animal model more closely related to humans. Methods We compared the effects of SP on genes associated with extracellular matrix (ECM) regulation, cell-cell adhesion, cell-matrix adhesion and ECM in cardiac fibroblasts isolated from a non-human primate and Sprague-Dawley rats. Results We found that rodent and non-human primate cardiac fibroblasts showed similar ECM regulation and cell adhesion gene expression responses to SP. There were, however, large discrepancies in ECM genes which did not result in collagen or laminin synthesis in rat or non-human primate fibroblasts in response to SP. Conclusions This study further supports the notion that SP serves as a ‘primer’ for fibroblasts rather than initiating direct effects and suggests that rodent fibroblasts are a suitable model for studying gene and functional responses to SP in the absence of human or non-human primate fibroblasts. PMID:25550118

A Confucian Perspective of Self-Cultivation in Learning: Its Implications for Self-Directed Learning

ERIC Educational Resources Information Center

Tan, Charlene

2017-01-01

This article explores a Confucian perspective of self-cultivation in learning and its implications for self-directed learning. Focussing on two key Confucian texts, "Xueji" (Record of Learning) and "Xunzi," this essay expounds the purpose, content, process and essence of self-cultivation in learning. From a Confucian viewpoint,…

The Multi-Domain Fibroblast/Myocyte Coupling in the Cardiac Tissue: A Theoretical Study.

PubMed

Greisas, Ariel; Zlochiver, Sharon

2016-09-01

Cardiac fibroblast proliferation and concomitant collagenous matrix accumulation (fibrosis) develop during multiple cardiac pathologies. Recent studies have demonstrated direct electrical coupling between myocytes and fibroblasts in vitro, and assessed the electrophysiological implications of such coupling. However, in the living tissues, such coupling has not been demonstrated, and only indirect coupling via the extracellular space is likely to exist. In this study we employed a multi-domain model to assess the modulation of the cardiac electrophysiological properties by neighboring fibroblasts assuming only indirect coupling. Numerical simulations in 1D and 2D human atrial models showed that extracellular coupling sustains a significant impact on conduction velocity (CV) and a less significant effect on the action potential duration. Both CV and the slope of the CV restitution increased with increasing fibroblast density. This effect was more substantial for lower extracellular conductance. In 2D, spiral waves exhibited reduced frequency with increasing fibroblast density, and the propensity of wavebreaks and complex dynamics at high pacing rates significantly increased.

Analysis of Self-Directed Learning upon Student of Mathematics Education Study Program

ERIC Educational Resources Information Center

Kleden, Maria Agustina

2015-01-01

Various studies have rendered self-directed learning disposition to be significant in the learning of mathematics, however several previous studies have pointed the level of self-directed learning disposition to be at a low point. This research is aimed to enhance self-directed learning through implementing a metacognitive strategy in learning…

Imaging multicellular specimens with real-time optimized tiling light-sheet selective plane illumination microscopy

PubMed Central

Fu, Qinyi; Martin, Benjamin L.; Matus, David Q.; Gao, Liang

2016-01-01

Despite the progress made in selective plane illumination microscopy, high-resolution 3D live imaging of multicellular specimens remains challenging. Tiling light-sheet selective plane illumination microscopy (TLS-SPIM) with real-time light-sheet optimization was developed to respond to the challenge. It improves the 3D imaging ability of SPIM in resolving complex structures and optimizes SPIM live imaging performance by using a real-time adjustable tiling light sheet and creating a flexible compromise between spatial and temporal resolution. We demonstrate the 3D live imaging ability of TLS-SPIM by imaging cellular and subcellular behaviours in live C. elegans and zebrafish embryos, and show how TLS-SPIM can facilitate cell biology research in multicellular specimens by studying left-right symmetry breaking behaviour of C. elegans embryos. PMID:27004937

Simulating the multicellular homeostasis with a cell-based discrete receptor dynamics model: The non-mutational origin of cancer and aging.

PubMed

Lou, Yuting; Chen, Yu

2016-09-07

The purpose of the study is to investigate the multicellular homeostasis in epithelial tissues over very large timescales. Inspired by the receptor dynamics of IBCell model proposed by Rejniak et al. an on-grid agent-based model for multicellular system is constructed. Instead of observing the multicellular architectural morphologies, the diversity of homeostatic states is quantitatively analyzed through a substantial number of simulations by measuring three new order parameters, the phenotypic population structure, the average proliferation age and the relaxation time to stable homeostasis. Nearby the interfaces of distinct homeostatic phases in 3D phase diagrams of the three order parameters, intermediate quasi-stable phases of slow dynamics that features quasi-stability with a large spectrum of relaxation timescales are found. A further exploration on the static and dynamic correlations among the three order parameters reveals that the quasi-stable phases evolve towards two terminations, tumorigenesis and degeneration, which are respectively accompanied by rejuvenation and aging. With the exclusion of the environmental impact and the mutational strategies, the results imply that cancer and aging may share the non-mutational origin in the intrinsic slow dynamics of the multicellular systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measuring Self-Directed Learning: A Diagnostic Tool for Adult Learners

ERIC Educational Resources Information Center

Khiat, Henry

2015-01-01

Self-directed learning is an important form of adult learning (Caffarella, 1993; Knowles, 1975; Knowles, Holton & Swanson, 2005; Merriam, 2001; Merriam & Caffarella, 1999). The strategies of self-directed learning allow adult learners to cope better with their studies while fulfilling family, work and other commitments. This study…

Developing Self-Directed Executive Functioning: Recent Findings and Future Directions

ERIC Educational Resources Information Center

Barker, Jane E.; Munakata, Yuko

2015-01-01

How do children become increasingly self-directed across development, achieving their goals without help from others? How might such developments be impacted by societal changes in how children spend their time? Children's abilities to achieve their goals are supported by developing executive functions (EFs), cognitive processes that predict…

The Direct/Indirect Association of ADHD/ODD Symptoms with Self-esteem, Self-perception, and Depression in Early Adolescents.

PubMed

Kita, Yosuke; Inoue, Yuki

2017-01-01

The present study aimed to reveal the influences of attention-deficit hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) symptoms on self-esteem and self-perception during early adolescence and to clarify the spillover effect of self-esteem on depressive symptoms. ADHD symptoms in 564 early adolescents were evaluated via teacher-rating scales. Self-esteem and depressive symptoms were assessed via self-reported scales. We analyzed the relationships among these symptoms using structural equation modeling. Severe inattentive symptoms decreased self-esteem and hyperactive-impulsive symptoms affected self-perception for non-academic domains. Although these ADHD symptoms did not directly affect depressive symptoms, low self-esteem led to severe depression. ODD symptoms had a direct impact on depression without the mediating effects of self-esteem. These results indicated that inattentive symptoms had a negative impact on self-esteem and an indirect negative effect on depressive symptoms in adolescents, even if ADHD symptoms were subthreshold. Severe ODD symptoms can be directly associated with depressive symptoms during early adolescence.

The 4-Celled Tetrabaena socialis Nuclear Genome Reveals the Essential Components for Genetic Control of Cell Number at the Origin of Multicellularity in the Volvocine Lineage.

PubMed

Featherston, Jonathan; Arakaki, Yoko; Hanschen, Erik R; Ferris, Patrick J; Michod, Richard E; Olson, Bradley J S C; Nozaki, Hisayoshi; Durand, Pierre M

2018-04-01

Multicellularity is the premier example of a major evolutionary transition in individuality and was a foundational event in the evolution of macroscopic biodiversity. The volvocine chlorophyte lineage is well suited for studying this process. Extant members span unicellular, simple colonial, and obligate multicellular taxa with germ-soma differentiation. Here, we report the nuclear genome sequence of one of the most morphologically simple organisms in this lineage-the 4-celled colonial Tetrabaena socialis and compare this to the three other complete volvocine nuclear genomes. Using conservative estimates of gene family expansions a minimal set of expanded gene families was identified that associate with the origin of multicellularity. These families are rich in genes related to developmental processes. A subset of these families is lineage specific, which suggests that at a genomic level the evolution of multicellularity also includes lineage-specific molecular developments. Multiple points of evidence associate modifications to the ubiquitin proteasomal pathway (UPP) with the beginning of coloniality. Genes undergoing positive or accelerating selection in the multicellular volvocines were found to be enriched in components of the UPP and gene families gained at the origin of multicellularity include components of the UPP. A defining feature of colonial/multicellular life cycles is the genetic control of cell number. The genomic data presented here, which includes diversification of cell cycle genes and modifications to the UPP, align the genetic components with the evolution of this trait.

Directed self-assembly of proteins into discrete radial patterns

PubMed Central

Thakur, Garima; Prashanthi, Kovur; Thundat, Thomas

2013-01-01

Unlike physical patterning of materials at nanometer scale, manipulating soft matter such as biomolecules into patterns is still in its infancy. Self-assembled monolayer (SAM) with surface density gradient has the capability to drive biomolecules in specific directions to create hierarchical and discrete structures. Here, we report on a two-step process of self-assembly of the human serum albumin (HSA) protein into discrete ring structures based on density gradient of SAM. The methodology involves first creating a 2-dimensional (2D) polyethylene glycol (PEG) islands with responsive carboxyl functionalities. Incubation of proteins on such pre-patterned surfaces results in direct self-assembly of protein molecules around PEG islands. Immobilization and adsorption of protein on such structures over time evolve into the self-assembled patterns. PMID:23719678

Self-directed learning in gross human anatomy: assessment outcomes and student perceptions.

PubMed

Smythe, Gayle; Hughes, Diane

2008-01-01

Speech pathology students enrolled in a lecture-based gross human anatomy program completed two out of nine topics in self-directed mode. Student performance in quizzes was compared for the two modes, and the students completed questionnaires on their perceptions of the self-directed mode of delivery. Students performed as well in the first self-directed topic as they did in lecture-based material, but performance declined significantly on the second self-directed topic. Correlations showed that students who performed well in lecture-based topics also performed well on self-directed topics. The major issues that arose in the student questionnaires were primarily related to the amount of content in the topics and the length of time required for completion. We conclude that there is a strong need for appropriate design of distance education materials to reflect student perceptions of length, content, and time investment, and more importantly that there is a need to ensure extensive communication and support of students studying in distance education/self-directed modes for the first time.

Effects of biomaterial-derived fibroblast conditioned medium on the α-amylase expression of parotid gland acinar cells.

PubMed

Chou, Ya-Shuan; Young, Tai-Horng; Lou, Pei-Jen

2015-11-01

Salivary gland cells are surrounded by a complex stromal environment, in which fibroblasts are the main cells in proximity to the gland cells. In this study, the interaction between parotid gland acinar cells (PGACs), fibroblasts, and biomaterials was investigated. We prepared different biomaterials, including chitosan, polyvinyl alcohol (PVA), poly (ethylene-co-vinyl alcohol) (EVAL), polyvinylidene fluoride (PVDF), and tissue culture polystyrene (TCPS) to culture fibroblasts and then collect their conditioned media to culture PGACs. We observed no difference in AQP3, AQP5, and E-cadherin expression among different fibroblast conditioned medium treatments. Interestingly, α-amylase expression was obviously enhanced in PGACs cultured in the presence of conditioned medium from fibroblasts cultured on PVDF. Higher neurotrophin-4 (NT-4) expression was observed in PVDF-derived fibroblast conditioned medium using a growth factor protein array assay. In addition, directly adding NT-4 into the culture medium significantly promoted α-amylase expression by PGACs. Finally, nestin and βIII-tubulin expression by fibroblasts cultured on PVDF was also enhanced. Together, these results suggest that PVDF could promote α-amylase expression by PGACs via the NT-4 produced by fibroblasts. To date, there is no effective therapy for patients with dry mouth with persistent salivary hypofunction. The study made use of different biomaterials to culture fibroblasts and then collect their conditioned media to culture PGACs. It was found that the effect of fibroblast conditioned medium from PVDF on the α-amylase expression of PGACs was obviously enhanced and higher neurotrophin-4 (NT-4) expression was found in PVDF-derived fibroblast conditioned medium. In addition, directly adding NT-4 into the culture medium significantly promoted the expression of α-amylase by PGACs and the expression of nestin and βIII-tubulin of fibroblasts after being cultured on PVDF was enhanced. Therefore, the

The swimming polarity of multicellular magnetotactic prokaryotes can change during an isolation process employing magnets: evidence of a relation between swimming polarity and magnetic moment intensity.

PubMed

de Melo, Roger Duarte; Acosta-Avalos, Daniel

2017-09-01

Magnetotactic microorganisms are characterized by swimming in the direction of an applied magnetic field. In nature, two types of swimming polarity have been observed: north-seeking microorganisms that swim in the same direction as the magnetic field, and south-seeking microorganisms that swim in the opposite direction. The present work studies the reversal in the swimming polarity of the multicellular magnetotactic prokaryote Candidatus Magnetoglobus multicellularis following an isolation process using high magnetic fields from magnets. The proportion of north- and south-seeking organisms was counted as a function of the magnetic field intensity used during the isolation of the organisms from sediment. It was observed that the proportion of north-seeking organisms increased when the magnetic field was increased. The magnetic moment for north- and south-seeking populations was estimated using the U-turn method. The average magnetic moment was higher for north- than south-seeking organisms. The results suggest that the reversal of swimming polarity must occur during the isolation process in the presence of high magnetic fields and magnetic field gradients. It is shown for the first time that the swimming polarity reversal depends on the magnetic moment intensity of multicellular magnetotactic prokaryotes, and new studies must be undertaken to understand the role of magnetic moment polarity and oxygen gradients in determination of swimming polarity.

The relationship between assessment methods and self-directed learning readiness in medical education.

PubMed

Monroe, Katherine S

2016-03-11

This research explored the assessment of self-directed learning readiness within the comprehensive evaluation of medical students' knowledge and skills and the extent to which several variables predicted participants' self-directed learning readiness prior to their graduation. Five metrics for evaluating medical students were considered in a multiple regression analysis. Fourth-year medical students at a competitive US medical school received an informed consent and an online survey. Participants voluntarily completed a self-directed learning readiness scale that assessed four subsets of self-directed learning readiness and consented to the release of their academic records. The assortment of metrics considered in this study only vaguely captured students' self-directedness. The strongest predictors were faculty evaluations of students' performance on clerkship rotations. Specific clerkship grades were mildly predictive of three subscales. The Pediatrics clerkship modestly predicted critical self-evaluation (r=-.30, p=.01) and the Psychiatry clerkship mildly predicted learning self-efficacy (r =-.30, p=.01), while the Junior Surgery clerkship nominally correlated with participants' effective organization for learning (r=.21, p=.05). Other metrics examined did not contribute to predicting participants' readiness for self-directed learning. Given individual differences among participants for the variables considered, no combination of students' grades and/or test scores overwhelmingly predicted their aptitude for self-directed learning. Considering the importance of fostering medical students' self-directed learning skills, schools need a reliable and pragmatic approach to measure them. This data analysis, however, offered no clear-cut way of documenting students' self-directed learning readiness based on the evaluation metrics included.

The hallmarks of fibroblast ageing.

PubMed

Tigges, Julia; Krutmann, Jean; Fritsche, Ellen; Haendeler, Judith; Schaal, Heiner; Fischer, Jens W; Kalfalah, Faiza; Reinke, Hans; Reifenberger, Guido; Stühler, Kai; Ventura, Natascia; Gundermann, Sabrina; Boukamp, Petra; Boege, Fritz

2014-06-01

Ageing is influenced by the intrinsic disposition delineating what is maximally possible and extrinsic factors determining how that frame is individually exploited. Intrinsic and extrinsic ageing processes act on the dermis, a post-mitotic skin compartment mainly consisting of extracellular matrix and fibroblasts. Dermal fibroblasts are long-lived cells constantly undergoing damage accumulation and (mal-)adaptation, thus constituting a powerful indicator system for human ageing. Here, we use the systematic of ubiquitous hallmarks of ageing (Lopez-Otin et al., 2013, Cell 153) to categorise the available knowledge regarding dermal fibroblast ageing. We discriminate processes inducible in culture from phenomena apparent in skin biopsies or primary cells from old donors, coming to the following conclusions: (i) Fibroblasts aged in culture exhibit most of the established, ubiquitous hallmarks of ageing. (ii) Not all of these hallmarks have been detected or investigated in fibroblasts aged in situ (in the skin). (iii) Dermal fibroblasts aged in vitro and in vivo exhibit additional features currently not considered ubiquitous hallmarks of ageing. (iv) The ageing process of dermal fibroblasts in their physiological tissue environment has only been partially elucidated, although these cells have been a preferred model of cell ageing in vitro for decades. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Mechanical compaction directly modulates the dynamics of bile canaliculi formation.

PubMed

Wang, Yan; Toh, Yi-Chin; Li, Qiushi; Nugraha, Bramasta; Zheng, Baixue; Lu, Thong Beng; Gao, Yi; Ng, Mary Mah Lee; Yu, Hanry

2013-02-01

Homeostatic pressure-driven compaction is a ubiquitous mechanical force in multicellular organisms and is proposed to be important in the maintenance of multicellular tissue integrity and function. Previous cell-free biochemical models have demonstrated that there are cross-talks between compaction forces and tissue structural functions, such as cell-cell adhesion. However, its involvement in physiological tissue function has yet to be directly demonstrated. Here, we use the bile canaliculus (BC) as a physiological example of a multicellular functional structure in the liver, and employ a novel 3D microfluidic hepatocyte culture system to provide an unprecedented opportunity to experimentally modulate the compaction states of primary hepatocyte aggregates in a 3D physiological-mimicking environment. Mechanical compaction alters the physical attributes of the hepatocyte aggregates, including cell shape, cell packing density and cell-cell contact area, but does not impair the hepatocytes' remodeling and functional capabilities. Characterization of structural and functional polarity shows that BC formation in compact hepatocyte aggregates is accelerated to as early as 12 hours post-seeding; whereas non-compact control requires 48 hours for functional BC formation. Further dynamic immunofluorescence imaging and gene expression profiling reveal that compaction accelerated BC formation is accompanied by changes in actin cytoskeleton remodeling dynamics and transcriptional levels of hepatic nuclear factor 4α and Annexin A2. Our report not only provides a novel strategy of modeling BC formation for in vitro hepatology research, but also shows a first instance that homeostatic pressure-driven compaction force is directly coupled to the higher-order multicellular functions.

Case study: Comparison of motivation for achieving higher performance between self-directed and manager-directed aerospace engineering teams

NASA Astrophysics Data System (ADS)

Erlick, Katherine

"The stereotype of engineers is that they are not people oriented; the stereotype implies that engineers would not work well in teams---that their task emphasis is a solo venture and does not encourage social aspects of collaboration" (Miner & Beyerlein, 1999, p. 16). The problem is determining the best method of providing a motivating environment where design engineers may contribute within a team in order to achieve higher performance in the organization. Theoretically, self-directed work teams perform at higher levels. But, allowing a design engineer to contribute to the team while still maintaining his or her anonymity is the key to success. Therefore, a motivating environment must be established to encourage greater self-actualization in design engineers. The purpose of this study is to determine the favorable motivational environment for design engineers and describe the comparison between two aerospace design-engineering teams: one self-directed and the other manager directed. Following the comparison, this study identified whether self-direction or manager-direction provides the favorable motivational environment for operating as a team in pursuit of achieving higher performance. The methodology used in this research was the case study focusing on the team's levels of job satisfaction and potential for higher performance. The collection of data came from three sources, (a) surveys, (b) researcher observer journal and (c) collection of artifacts. The surveys provided information regarding personal behavior characteristics, potentiality for higher performance and motivational attributes. The researcher journal provided information regarding team dynamics, individual interaction, conflict and conflict resolution. The milestone for performance was based on the collection of artifacts from the two teams. The findings from this study illustrated that whether the team was manager-directed or self-directed does not appear to influence the needs and wants of the

Surgical skill acquisition with self-directed practice using computer-based video training.

PubMed

Jowett, Nathan; LeBlanc, Vicki; Xeroulis, George; MacRae, Helen; Dubrowski, Adam

2007-02-01

Computer-based video training (CBVT) provides flexible opportunities for surgical trainees to learn fundamental technical skills, but may be ineffective in self-directed practice settings because of poor trainee self-assessment. This study examined whether CBVT is effective in a self-directed learning environment among novice trainees. Thirty novice trainees used CBVT to learn the 1-handed square knot while self-assessing their proficiency every 3 minutes. On reaching self-assessed skill proficiency, trainees were randomized to either cease practice or to complete additional practice. Performance was evaluated with computer and expert-based measures during practice and on pretests, posttests, and 1-week retention tests. Analyses revealed performance improvements for both groups (all P < .05), but no differences between the 2 groups (all P > .05) on all tests. CBVT for the 1-handed square knot is effective in a self-directed learning environment among novices. This lends support to the implementation of self-directed digital media-based learning within surgical curricula.

Self-Directed Digital Learning: When Do Dental Students Study?

PubMed

Jackson, Tate H; Zhong, James; Phillips, Ceib; Koroluk, Lorne D

2018-04-01

The Growth and Development (G&D) curriculum at the University of North Carolina at Chapel Hill School of Dentistry uses self-directed web-based learning modules in the place of lectures and includes scheduled self-study times during the 8 am-5 pm school hours. The aim of this study was to use direct observation to evaluate dental students' access patterns with the self-directed, web-based learning modules in relation to planned self-study time allocated across the curriculum, proximity to course examinations, and course performance. Module access for all 80 students in the DDS Class of 2014 was recorded for date and time across the four G&D courses. Module access data were used to determine likelihood of usage during scheduled time and frequency of usage in three timeframes: >7, 3 to 7, and 0 to 2 days before the final exam. The results showed a statistically significant difference in the likelihood of module access during scheduled time across the curriculum (p<0.0001). Among the students, 64% accessed modules at least once during scheduled time in G&D1, but only 10%, 19%, and 18% in G&D2, G&D3, and G&D4, respectively. For all courses, the proportion of module accesses was significantly higher 0-2 days before an exam compared to the other two timeframes. Module access also differed significantly within each timeframe across all four courses (p<0.001). There was no association between module access and course performance. In this non-traditional, non-lecture, self-directed curriculum, students rarely accessed learning modules during syllabus-budgeted self-study time and accessed modules more frequently as course exams approached.

Altered interactions between unicellular and multicellular genes drive hallmarks of transformation in a diverse range of solid tumors.

PubMed

Trigos, Anna S; Pearson, Richard B; Papenfuss, Anthony T; Goode, David L

2017-06-13

Tumors of distinct tissues of origin and genetic makeup display common hallmark cellular phenotypes, including sustained proliferation, suppression of cell death, and altered metabolism. These phenotypic commonalities have been proposed to stem from disruption of conserved regulatory mechanisms evolved during the transition to multicellularity to control fundamental cellular processes such as growth and replication. Dating the evolutionary emergence of human genes through phylostratigraphy uncovered close association between gene age and expression level in RNA sequencing data from The Cancer Genome Atlas for seven solid cancers. Genes conserved with unicellular organisms were strongly up-regulated, whereas genes of metazoan origin were primarily inactivated. These patterns were most consistent for processes known to be important in cancer, implicating both selection and active regulation during malignant transformation. The coordinated expression of strongly interacting multicellularity and unicellularity processes was lost in tumors. This separation of unicellular and multicellular functions appeared to be mediated by 12 highly connected genes, marking them as important general drivers of tumorigenesis. Our findings suggest common principles closely tied to the evolutionary history of genes underlie convergent changes at the cellular process level across a range of solid cancers. We propose altered activity of genes at the interfaces between multicellular and unicellular regions of human gene regulatory networks activate primitive transcriptional programs, driving common hallmark features of cancer. Manipulation of cross-talk between biological processes of different evolutionary origins may thus present powerful and broadly applicable treatment strategies for cancer.

Altered interactions between unicellular and multicellular genes drive hallmarks of transformation in a diverse range of solid tumors

PubMed Central

Trigos, Anna S.; Pearson, Richard B.; Papenfuss, Anthony T.; Goode, David L.

2017-01-01

Tumors of distinct tissues of origin and genetic makeup display common hallmark cellular phenotypes, including sustained proliferation, suppression of cell death, and altered metabolism. These phenotypic commonalities have been proposed to stem from disruption of conserved regulatory mechanisms evolved during the transition to multicellularity to control fundamental cellular processes such as growth and replication. Dating the evolutionary emergence of human genes through phylostratigraphy uncovered close association between gene age and expression level in RNA sequencing data from The Cancer Genome Atlas for seven solid cancers. Genes conserved with unicellular organisms were strongly up-regulated, whereas genes of metazoan origin were primarily inactivated. These patterns were most consistent for processes known to be important in cancer, implicating both selection and active regulation during malignant transformation. The coordinated expression of strongly interacting multicellularity and unicellularity processes was lost in tumors. This separation of unicellular and multicellular functions appeared to be mediated by 12 highly connected genes, marking them as important general drivers of tumorigenesis. Our findings suggest common principles closely tied to the evolutionary history of genes underlie convergent changes at the cellular process level across a range of solid cancers. We propose altered activity of genes at the interfaces between multicellular and unicellular regions of human gene regulatory networks activate primitive transcriptional programs, driving common hallmark features of cancer. Manipulation of cross-talk between biological processes of different evolutionary origins may thus present powerful and broadly applicable treatment strategies for cancer. PMID:28484005

Doxorubicin-mediated radiosensitivity in multicellular spheroids from a lung cancer cell line is enhanced by composite micelle encapsulation

PubMed Central

Xu, Wen-Hong; Han, Min; Dong, Qi; Fu, Zhi-Xuan; Diao, Yuan-Yuan; Liu, Hai; Xu, Jing; Jiang, Hong-Liang; Zhang, Su-Zhan; Zheng, Shu; Gao, Jian-Qing; Wei, Qi-Chun

2012-01-01

Background The purpose of this study is to evaluate the efficacy of composite doxorubicinloaded micelles for enhancing doxorubicin radiosensitivity in multicellular spheroids from a non-small cell lung cancer cell line. Methods A novel composite doxorubicin-loaded micelle consisting of polyethylene glycolpolycaprolactone/Pluronic P105 was developed, and carrier-mediated doxorubicin accumulation and release from multicellular spheroids was evaluated. We used confocal laser scanning microscopy and flow cytometry to study the accumulation and efflux of doxorubicin from A549 multicellular spheroids. Doxorubicin radiosensitization and the combined effects of irradiation and doxorubicin on cell migration and proliferation were compared for the different doxorubicin delivery systems. Results Confocal laser scanning microscopy and quantitative flow cytometry studies both verified that, for equivalent doxorubicin concentrations, composite doxorubicin-loaded micelles significantly enhanced cellular doxorubicin accumulation and inhibited doxorubicin release. Colony-forming assays demonstrated that composite doxorubicin-loaded micelles are radiosensitive, as shown by significantly reduced survival of cells treated by radiation + composite micelles compared with those treated with radiation + free doxorubicin or radiation alone. The multicellular spheroid migration area and growth ability verified higher radiosensitivity for the composite micelles loaded with doxorubicin than for free doxorubicin. Conclusion Our composite doxorubicin-loaded micelle was demonstrated to have radiosensitization. Doxorubicin loading in the composite micelles significantly increased its cellular uptake, improved drug retention, and enhanced its antitumor effect relative to free doxorubicin, thereby providing a novel approach for treatment of cancer. PMID:22679376

Notch3 protein expression in skin fibroblasts from CADASIL patients.

PubMed

Qualtieri, Antonio; Ungaro, Carmine; Bagalà, Angelo; Bianchi, Silvia; Pantoni, Leonardo; Moccia, Marcello; Mazzei, Rosalucia

2018-07-15

CADASIL is an inherited cerebrovascular disease caused by mutations in the NOTCH3 gene. Notch signaling is involved in a broad spectrum of function, from the cell proliferation to apoptosis. Thus far, because the molecular mechanism underlying the pathological alterations remains unclear and taking into account that fibroblasts contribute to the integrity of the vasculature, our aims was to establish whether fibroblasts, in subjects carrying different NOTCH3 mutations, show abnormalities in the protein expression. We performed the investigation on skin fibroblasts in culture obtained from three CADASIL patients and normal subjects. The patients were genetically characterized, and carried a p.R61W, a p.C174T, and p.R103X, mutation respectively. Notch3 expression was first evaluated on fibroblasts by immunofluorescence analysis, then western blot on cellular extract was utilized to validate the immunofluorescence results. The Notch3 immunoreactivity was clearly detected along the cellular body and in the cellular nuclei of the control fibroblasts. We observed a marked, statistically significant, reduction of the fluorescence immunoreactivity in the fibroblasts from patient with the classical C174T cysteine mutation and a less pronounced reduction in the other two subject's samples with respect to the normal controls. These data were confirmed by the immunoblot analysis. Our results show that the investigated three NOTCH3 mutations are associated with a reduction of the levels of Notch3 expression in vitro. Because the smooth muscle cells appear to be predominantly involved in this cerebrovascular disease, our result, despite the limitation of the sample size examinated, clearly suggest that also fibroblasts, directly involved in making the vascular basal lamina and in maintaining the vascular integrity, may play an important role in the mechanism responsible for the disease. Copyright © 2018 Elsevier B.V. All rights reserved.

Simple systems that exhibit self-directed replication

NASA Technical Reports Server (NTRS)

Reggia, James A.; Armentrout, Steven L.; Chou, Hui-Hsien; Peng, Yun

1993-01-01

Biological experience and intuition suggest that self-replication is an inherently complex phenomenon, and early cellular automata models support that conception. More recently, simpler computational models of self-directed replication called sheathed loops have been developed. It is shown here that 'unsheathing' these structures and altering certain assumptions about the symmetry of their components leads to a family of nontrivial self-replicating structures some substantially smaller and simpler than those previously reported. The dependence of replication time and transition function complexity on initial structure size, cell state symmetry, and neighborhood are examined. These results support the view that self-replication is not an inherently complex phenomenon but rather an emergent property arising from local interactions in systems that can be much simpler than is generally believed.

Fibroblast growth factor receptors in breast cancer.

PubMed

Wang, Shuwei; Ding, Zhongyang

2017-05-01

Fibroblast growth factor receptors are growth factor receptor tyrosine kinases, exerting their roles in embryogenesis, tissue homeostasis, and development of breast cancer. Recent genetic studies have identified some subtypes of fibroblast growth factor receptors as strong genetic loci associated with breast cancer. In this article, we review the recent epidemiological findings and experiment results of fibroblast growth factor receptors in breast cancer. First, we summarized the structure and physiological function of fibroblast growth factor receptors in humans. Then, we discussed the common genetic variations in fibroblast growth factor receptors that affect breast cancer risk. In addition, we also introduced the potential roles of each fibroblast growth factor receptors isoform in breast cancer. Finally, we explored the potential therapeutics targeting fibroblast growth factor receptors for breast cancer. Based on the biological mechanisms of fibroblast growth factor receptors leading to the pathogenesis in breast cancer, targeting fibroblast growth factor receptors may provide new opportunities for breast cancer therapeutic strategies.

The Direct/Indirect Association of ADHD/ODD Symptoms with Self-esteem, Self-perception, and Depression in Early Adolescents

PubMed Central

Kita, Yosuke; Inoue, Yuki

2017-01-01

The present study aimed to reveal the influences of attention-deficit hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) symptoms on self-esteem and self-perception during early adolescence and to clarify the spillover effect of self-esteem on depressive symptoms. ADHD symptoms in 564 early adolescents were evaluated via teacher-rating scales. Self-esteem and depressive symptoms were assessed via self-reported scales. We analyzed the relationships among these symptoms using structural equation modeling. Severe inattentive symptoms decreased self-esteem and hyperactive–impulsive symptoms affected self-perception for non-academic domains. Although these ADHD symptoms did not directly affect depressive symptoms, low self-esteem led to severe depression. ODD symptoms had a direct impact on depression without the mediating effects of self-esteem. These results indicated that inattentive symptoms had a negative impact on self-esteem and an indirect negative effect on depressive symptoms in adolescents, even if ADHD symptoms were subthreshold. Severe ODD symptoms can be directly associated with depressive symptoms during early adolescence. PMID:28824468

Self-Directed Learning Characteristics: Making Learning Personal, Empowering and Successful

ERIC Educational Resources Information Center

du Toit-Brits, Charlene; van Zyl, Chris-Mari

2017-01-01

Due to the speedy emergent investigation in self-directed learning (SDL) over the past 40 years, SDL is an education technique used progressively within tertiary institutions. SDL can be well-defined in terms of the amount of accountability the student accepts for his or her own learning. The self-directed students regarding learning take control…

Aging and health: Self-efficacy for Self-direction in Health Scale.

PubMed

Oliveira, Albertina L; Silva, José T; Lima, Margarida P

2016-07-04

To validate the Escala de Autoeficácia para a Autodireção na Saúde (EAAS - Self-efficacy for Self-direction in Health Scale). Non-experimental quantitative study of EAAS validation, by confirmatory factorial analyses, evaluating a sample of 508 older adults from the north and the center of Portugal with mean age of 71.67 (from 51 to 96 years), to whom the Self-efficacy for Self-direction in Health Scale, the Rosenberg Self-esteem Scale, the Positive and Negative Affect Schedule, the Satisfaction with Life Scale, and the Instrumental Activities of Daily Living Scale were applied. The EAAS was developed from the theoretical constructs of self-efficacy and from self-directed learning within the PALADIN European project framework, aiming to develop an instrument able to assess the extent to which older adults take good care of their health. The internal consistency was 0.87 (Cronbach's alpha) and confirmatory factorial analyses enabled to find a model near the one theoretically proposed, indicating a structure consisting of four dimensions: physical exercise, healthy diet, engaging in health-related learning, and visits to health professionals. From the psychometric point of view, the model in four factors showed quite satisfactory fit indicators. The Self-efficacy for Self-direction in Health Scale, with 16 items, is adequate to evaluate to what extent older adults have confidence in their ability to take care of their own health, with high degree of autonomy. Validar a Escala de Autoeficácia para a Autodireção no domínio da Saúde (EAAS). Estudo quantitativo não experimental de validação da EAAS, por meio de análises fatoriais confirmatórias, avaliando amostra de 508 seniores e idosos provenientes das regiões Norte e Centro de Portugal com média etária de 71.67 (51 a 96 anos), a quem foram aplicadas a Escala de Autoeficácia para a Autodireção na Saúde, a Escala de Autoestima de Rosenberg, a Escala de Afeto Positivo e Afeto Negativo, a Escala de

NCS-1 dependent learning bonus and behavior outputs of self-directed exploration

NASA Astrophysics Data System (ADS)

Mun, Ho-Suk

Animals explore a new environment and learn about their surroundings. "Exploration" refers to all activities that increase the information obtained from an animal. For this study, I determined a molecule that mediates self-directed exploration, with a particular focus on rearing behavior and vocalization. Rearing can be either self-directed exploration or escape-oriented exploration. Self-directed exploration can be driven by the desire to gather information about environments while escape-oriented exploration can be driven by fear or anxiety. To differentiate between these two concepts, I compared rearing and other behaviors in three different conditions 1) novel dim (safe environment), which induces exploration based rearing; 2) novel bright (fearful environment), which elicits fear driven rearing; and 3) familiar environment as a control. First, I characterized the effects on two distinct types of environment in exploratory behavior and its effect on learning. From this, I determined that self-directed exploration enhances spatial learning while escape-oriented exploration does not produce a learning bonus. Second, I found that NCS-1 is involved in exploration, as well as learning and memory, by testing mice with reduced levels of Ncs-1 by point mutation and also siRNA injection. Finally, I illustrated other behavior outputs and neural substrate activities, which co-occurred during either self-directed or escape-oriented exploration. I found that high-frequency ultrasonic vocalizations occurred during self-directed exploration while low-frequency calls were emitted during escape-oriented exploration. Also, with immediate early gene imaging techniques, I found hippocampus and nucleus accumbens activation in self-directed exploration. This study is the first comprehensive molecular analysis of learning bonus in self-directed exploration. These results may be beneficial for studying underlying mechanisms of neuropsychiatric disease, and also reveal therapeutic

Principal Development: Self-Directed Project Efficacy

ERIC Educational Resources Information Center

Piggot-Irvine, Eileen

2011-01-01

The inclusion of self-directed projects as an element within a New Zealand principal development programme was designed to reflect increasing support internationally for such a context-specific "inquiry" approach. The results reported in this article suggest that considerable clarity is required for such projects if they are to realize…

Bridging the gap between self-directed learning of nurse educators and effective student support.

PubMed

Van Rensburg, Gisela H; Botma, Yvonne

2015-11-26

Self-directed learning requires the ability to identify one's own learning needs, develop and implement a plan to gain knowledge and to monitor one's own progress. A lifelong learning approach cannot be forced, since it is in essence an internally driven process. Nurse educators can, however, act as role models to empower their students to become independent learners by modelling their own self-directed learning and applying a number of techniques in supporting their students in becoming ready for self-directed learning.  The aim of the article is to describe the manifestations and implications of the gap between self-directed learning readiness of nurse educators and educational trends in supporting students.  An instrumental case study design was used to gain insight into the manifestations and implications of self-directed learning of nurse educators. Based on the authentic foci of various critical incidents and literature, data were collected and constructed into a fictitious case. The authors then deductively analysed the case by using the literature on self-directed learning readiness as departure point. Four constructs of self-directed learning were identified, namely internal motivation, planning and implementation, self-monitoring and interpersonal communication. Supportive strategies were identified from the available literature.  Nine responses by nurse educators based on the fictitious case were analysed.Analysis showed that readiness for self-directed learning in terms of the identified constructswas interrelated and not mutually exclusive of one other.  The success of lifelong learning is the ability to engage in self-directed learning which requires openness to learning opportunities, good self-concept, taking initiative and illustrating independence in learning. Conscientiousness, an informed acceptance of a responsibility for one's own learning and creativity, is vital to one's future orientation towards goal-directed learning. Knowledge and

The interplay between genetic and bioelectrical signaling permits a spatial regionalisation of membrane potentials in model multicellular ensembles

PubMed Central

Cervera, Javier; Meseguer, Salvador; Mafe, Salvador

2016-01-01

The single cell-centred approach emphasises ion channels as specific proteins that determine individual properties, disregarding their contribution to multicellular outcomes. We simulate the interplay between genetic and bioelectrical signals in non-excitable cells from the local single-cell level to the long range multicellular ensemble. The single-cell genetic regulation is based on mean-field kinetic equations involving the mRNA and protein concentrations. The transcription rate factor is assumed to depend on the absolute value of the cell potential, which is dictated by the voltage-gated cell ion channels and the intercellular gap junctions. The interplay between genetic and electrical signals may allow translating single-cell states into multicellular states which provide spatio-temporal information. The model results have clear implications for biological processes: (i) bioelectric signals can override slightly different genetic pre-patterns; (ii) ensembles of cells initially at the same potential can undergo an electrical regionalisation because of persistent genetic differences between adjacent spatial regions; and (iii) shifts in the normal cell electrical balance could trigger significant changes in the genetic regulation. PMID:27731412

The interplay between genetic and bioelectrical signaling permits a spatial regionalisation of membrane potentials in model multicellular ensembles.

PubMed

Cervera, Javier; Meseguer, Salvador; Mafe, Salvador

2016-10-12

The single cell-centred approach emphasises ion channels as specific proteins that determine individual properties, disregarding their contribution to multicellular outcomes. We simulate the interplay between genetic and bioelectrical signals in non-excitable cells from the local single-cell level to the long range multicellular ensemble. The single-cell genetic regulation is based on mean-field kinetic equations involving the mRNA and protein concentrations. The transcription rate factor is assumed to depend on the absolute value of the cell potential, which is dictated by the voltage-gated cell ion channels and the intercellular gap junctions. The interplay between genetic and electrical signals may allow translating single-cell states into multicellular states which provide spatio-temporal information. The model results have clear implications for biological processes: (i) bioelectric signals can override slightly different genetic pre-patterns; (ii) ensembles of cells initially at the same potential can undergo an electrical regionalisation because of persistent genetic differences between adjacent spatial regions; and (iii) shifts in the normal cell electrical balance could trigger significant changes in the genetic regulation.

Coherent Timescales and Mechanical Structure of Multicellular Aggregates.

PubMed

Yu, Miao; Mahtabfar, Aria; Beelen, Paul; Demiryurek, Yasir; Shreiber, David I; Zahn, Jeffrey D; Foty, Ramsey A; Liu, Liping; Lin, Hao

2018-06-05

Multicellular aggregates are an excellent model system to explore the role of tissue biomechanics in specifying multicellular reorganization during embryonic developments and malignant invasion. Tissue-like spheroids, when subjected to a compressive force, are known to exhibit liquid-like behaviors at long timescales (hours), largely because of cell rearrangements that serve to effectively dissipate the applied stress. At short timescales (seconds to minutes), before cell rearrangement, the mechanical behavior is strikingly different. The current work uses shape relaxation to investigate the structural characteristics of aggregates and discovers two coherent timescales: one on the order of seconds, the other tens of seconds. These timescales are universal, conserved across a variety of tested species, and persist despite great differences in other properties such as tissue surface tension and adhesion. A precise mathematical theory is used to correlate the timescales with mechanical properties and reveals that aggregates have a relatively strong envelope and an unusually "soft" interior (weak bulk elastic modulus). This characteristic is peculiar, considering that both layers consist of identical units (cells), but is consistent with the fact that this structure can engender both structural integrity and the flexibility required for remodeling. In addition, tissue surface tension, elastic modulus, and viscosity are proportional to each other. Considering that these tissue-level properties intrinsically derive from cellular-level properties, the proportionalities imply precise coregulation of the latter and in particular of the tension on the cell-medium and cell-cell interfaces. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Laser microdissection and capture of pure cardiomyocytes and fibroblasts from infarcted heart regions: perceived hyperoxia induces p21 in peri-infarct myocytes.

PubMed

Kuhn, Donald E; Roy, Sashwati; Radtke, Jared; Khanna, Savita; Sen, Chandan K

2007-03-01

Myocardial infarction caused by ischemia-reperfusion in the coronary vasculature is a focal event characterized by an infarct-core, bordering peri-infarct zone and remote noninfarct zone. Recently, we have reported the first technique, based on laser microdissection pressure catapulting (LMPC), enabling the dissection of infarction-induced biological responses in multicellular regions of the heart. Molecular mechanisms in play at the peri-infarct zone are central to myocardial healing. At the infarct site, myocytes are more sensitive to insult than robust fibroblasts. Understanding of cell-specific responses in the said zones is therefore critical. In this work, we describe the first technique to collect the myocardial tissue with a single-cell resolution. The infarcted myocardium was identified by using a truncated hematoxylin-eosin stain. Cell elements from the infarct, peri-infarct, and noninfarct zones were collected in a chaotropic RNA lysis solution with micron-level surgical precision. Isolated RNA was analyzed for quality by employing microfluidics technology and reverse transcribed to generate cDNA. Purity of the collected specimen was established by real-time PCR analyses of cell-specific genes. Previously, we have reported that the oxygen-sensitive induction of p21/Cip1/Waf1/Sdi1 in cardiac fibroblasts in the peri-infarct zone plays a vital role in myocardial remodeling. Using the novel LMPC technique developed herein, we confirmed that finding and report for the first time that the induction of p21 in the peri-infarct zone is not limited to fibroblasts but is also evident in myocytes. This work presents the first account of an analytical technique that applies the LMPC technology to study myocardial remodeling with a cell-type specific resolution.

Basic Fibroblast Growth Factor Influences Epidermal Homeostasis of Living Skin Equivalents through Affecting Fibroblast Phenotypes and Functions.

PubMed

Yang, Lujun; Zhang, Dangui; Wu, Hongjuan; Xie, Sitian; Zhang, Mingjun; Zhang, Bingna; Tang, Shijie

2018-05-30

To elucidate the possible mechanisms of how basic fibroblast growth factor (bFGF) influences epidermal homeostasis in a living skin equivalent (LSE) model. Several wound healing-related growth factors were analyzed at protein and mRNA levels for dermal fibroblasts of induced alpha-smooth muscle actin (α-SMA)-positive or α-SMA-negative phenotypes. During culturing an LSE model by seeding normal human keratinocytes on a fibroblast-populated type I collagen gel, bFGF or neutralizing antibody for keratinocyte growth factor (KGF) was added to investigate its effects on fibroblast phenotypes and, subsequently, epidermal homeostasis by histology and immunohistochemistry. The α-SMA-positive phenotype of fibroblasts induced by transforming growth factor beta-1 (TGF-β1) markedly suppressed the expression of KGF and hepatocyte growth factor (HGF), and slightly upregulated vascular endothelial growth factor (VEGF) and TGF-β1 at mRNA and protein levels, compared with α-SMA-negative fibroblasts treated with bFGF. α-SMA expression of fibroblasts at the epidermal-mesenchymal junction of the LSEs was suppressed by the addition of bFGF, and a better-differentiated epidermis was presented. The abrogation of KGF from fibroblasts by the addition of the KGF neutralizing antibody disenabled the LSE culturing system to develop an epidermis. bFGF, through affecting the phenotypes and functions of fibroblasts, especially KGF expression, influenced epidermal homeostasis in an LSE model. © 2018 S. Karger AG, Basel.

Non-suicidal self-injury and other self-directed violent behaviors in India: A review of definitions and research.

PubMed

Gandhi, Amarendra; Luyckx, Koen; Maitra, Shubhada; Claes, Laurence

2016-08-01

The interpersonal theory of suicide suggests that most forms of self-directed violent behaviors lie on a continuum, with each behavior successively increasing the capability of committing suicide. There is increasing evidence to suggest that the continuum may begin with Non-Suicidal Self-Injury (NSSI). This theory can be important in developing interventions for suicide prevention. However, in India, consistent usage of definitions of various forms of self-directed violent behaviors is lacking. In the present study, we reviewed definitions of various forms of self-directed violent behaviors that have been investigated in India. Further, we compared the usage of these definitions with the usage by WHO. Additionally, we reviewed NSSI research in India. Thirty-eight publications were identified by a comprehensive electronic search undertaken in Indian psychiatry, psychology, and mental health-related databases. Inconsistent definitions of eight self-directed violent behaviors were observed in Indian literature. Agreement on consistent definitions of various forms of self-directed behaviors is essential. Based on the findings of the current review, it can be suggested that culturally relevant large-scale research on NSSI in India is required to confirm the limited evidence that suggests high prevalence of NSSI in India. Copyright © 2015 Elsevier B.V. All rights reserved.

The Nature of Self-Directed Learning and Transformational Learning in Self-Managing Bipolar Disorder to Stay Well

ERIC Educational Resources Information Center

Francik, Wendy A.

2012-01-01

The purpose of the research was to explore the self-directed learning and transformational learning experiences among persons with bipolar disorder. A review of previous research pointed out how personal experiences with self-directed learning and transformational learning facilitated individuals' learning to manage HIV, Methicillan-resitant…

Automatic inference of multicellular regulatory networks using informative priors.

PubMed

Sun, Xiaoyun; Hong, Pengyu

2009-01-01

To fully understand the mechanisms governing animal development, computational models and algorithms are needed to enable quantitative studies of the underlying regulatory networks. We developed a mathematical model based on dynamic Bayesian networks to model multicellular regulatory networks that govern cell differentiation processes. A machine-learning method was developed to automatically infer such a model from heterogeneous data. We show that the model inference procedure can be greatly improved by incorporating interaction data across species. The proposed approach was applied to C. elegans vulval induction to reconstruct a model capable of simulating C. elegans vulval induction under 73 different genetic conditions.

Intersectional policy analysis of self-directed mental health care in Canada.

PubMed

Cook, Judith A; Morrow, Marina; Battersby, Lupin

2017-06-01

Recovery from mental illness is influenced by one's social location along multiple dimensions of identity, such as race, class, gender, age, and ability, and by how these social locations are expressed through structural and institutional barriers. This project was developed using an intersectional policy analysis framework designed to promote equity across identity locations-called the multistrand method-to examine the potential use of self-directed care financing approaches in the Canadian mental health system. A panel of 16 diverse stakeholders came together 4 times at structured 6-hr meetings to examine the evidence for self-directed care and explore its application in the Canadian context. Telephone interviews with evidence panel members were conducted to assess their perceptions of the group process and outcomes. Our analysis revealed ways that intersecting strand locations might differentially influence the degree of choice and recovery experienced by self-directed care participants. Individualized resource allocation, draining financial resources from ethnically specific services, unevenness in acceptance of the recovery orientation, and paucity of service options in different geographical regions were identified as contexts in which self-directed care policies could promote inequity. However, greater peer involvement in the model's implementation, use of indigenous community supports, purchase of material goods by economically disenfranchised persons, and access to services from ethnically diverse clinicians in the private sector were identified as equity-promoting model features. By couching their analysis at the level of unique socially-situated perspectives, the group developed detailed policy recommendations and insights into both the potential and limitations of self-directed care. The knowledge gained from our project can be used to develop uniquely Canadian self-directed care models tailored to promote recovery through empowerment and self

The Role of Self-Reflection, Emotional Management of Feedback, and Self-Regulation Processes in Self-Directed Leadership Development

ERIC Educational Resources Information Center

Nesbit, Paul L.

2012-01-01

This article presents and explores a framework of self-directed leadership development (SDLD) to advance conceptual understanding and practical applications for self-development approaches to development of leaders in organizations. Drawing on a diversified literature associated with experiential learning, emotion research, and social cognitive…

Three-dimensional transgenic cell model to quantify genotoxic effects of space environment

NASA Astrophysics Data System (ADS)

Gonda, S. R.; Wu, H.; Pingerelli, P. L.; Glickman, B. W.

In this paper we describe a three-dimensional, multicellular tissue-equivalent model, produced in NASA-designed, rotating wall bioreactors using mammalian cells engineered for genomic containment of multiple copies of defined target genes for genotoxic assessment. Rat 2λ fibroblasts, genetically engineered to contain high-density target genes for mutagenesis (Stratagene, Inc., Austin, TX), were cocultured with human epithelial cells on Cytodex beads in the High Aspect Ratio Bioreactor (Synthecon, Inc, Houston, TX). Multi-bead aggregates were formed by day 5 following the complete covering of the beads by fibroblasts. Cellular retraction occurred 8-14 days after coculture initiation culminating in spheroids retaining few or no beads. Analysis of the resulting tissue assemblies revealed: multicellular spheroids, fibroblasts synthesized collagen, and cell viability was retained for the 30-day test period after removal from the bioreactor. Quantification of mutation at the LacI gene in Rat 2λ fibroblasts in spheroids exposed to 0-2 Gy neon using the Big Blue color assay (Stratagene, Inc.), revealed a linear dose-response for mutation induction. Limited sequencing analysis of mutant clones from 0.25 or 1 Gy exposures revealed a higher frequency of deletions and multiple base sequencing changes with increasing dose. These results suggest that the three-dimensional, multicellular tissue assembly model produced in NASA bioreactors are applicable to a wide variety of studies involving the quantification and identification of genotocity including measurement of the inherent damage incurred in Space.

Directed Self-Assembly of Gradient Concentric Carbon Nanotube Rings

NASA Astrophysics Data System (ADS)

Hong, Suck Won; Jeong, Wonje; Ko, Hyunhyub; Tsukruk, Vladimir; Kessler, Michael; Lin, Zhiqun

2008-03-01

Hundreds of gradient concentric rings of linear conjugated polymer, (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4- phenylenevinylene], i.e., MEH-PPV) with remarkable regularity over large areas were produced by controlled, repetitive ``stick- slip'' motions of the contact line in a confined geometry consisting of a sphere on a flat substrate (i.e., sphere-on-flat geometry). Subsequently, MEH-PPV rings exploited as template to direct the formation of gradient concentric rings of multiwalled carbon nanotubes (MWNTs) with controlled density. This method is simple, cost effective, and robust, combining two consecutive self-assembly processes, namely, evaporation-induced self- assembly of polymers in a sphere-on-flat geometry, followed by subsequent directed self-assembly of MWNTs on the polymer- templated surfaces.

A generalized view of self-citation: direct, co-author, collaborative, and coercive induced self-citation.

PubMed

Ioannidis, John P A

2015-01-01

The phenomenon of self-citation can present in many different forms, including direct, co-author, collaborative, and coercive induced self-citation. It can also pertain to the citation of single scientists, groups of scientists, journals, and institutions. This article presents some case studies of extreme self-citation practices. It also discusses the implications of different types of self-citation. Self-citation is not necessarily inappropriate by default. In fact, usually it is fully appropriate but often it is even necessary. Conversely, inappropriate self-citation practices may be highly misleading and may distort the scientific literature. Coercive induced self-citation is the most difficult to discover. Coercive Induced self-citation may happen directly from reviewers of articles, but also indirectly from reviewers of grants, scientific advisors who steer a research agenda, and leaders of funding agencies who may espouse spending disproportionately large funds in research domains that perpetuate their own self-legacy. Inappropriate self-citation can be only a surrogate marker of what might be much greater distortions of the scientific corpus towards conformity to specific opinions and biases. Inappropriate self-citations eventually affect also impact metrics. Different impact metrics vary in the extent to which they can be gamed through self-citation practices. Citation indices that are more gaming-proof are available and should be more widely used. We need more empirical studies to dissect the impact of different types of inappropriate self-citation and to examine the effectiveness of interventions to limit them. Copyright © 2014. Published by Elsevier Inc.

The CC chemokine eotaxin/CCL11 has a selective profibrogenic effect on human lung fibroblasts.

PubMed

Puxeddu, Ilaria; Bader, Reem; Piliponsky, Adrian Martin; Reich, Reuven; Levi-Schaffer, Francesca; Berkman, Neville

2006-01-01

Eotaxin/CCL11 plays an important role in asthma. It acts through the chemokine receptor CCR3 expressed on hematopoietic and nonhematopoietic cells in the lung. To determine whether eotaxin/CCL11 modulates lung and bronchial fibroblast properties and thereby might contribute to airway remodeling. CCR3 expression was characterized on a lung fibroblast line (MRC-5; flow cytometry, fluorescent microscopy, RT-PCR, and Northern blotting), on primary bronchial fibroblasts (flow cytometry), and on fibroblasts in human lung tissue (confocal laser microscopy). The effects of eotaxin/CCL11 on lung fibroblast migration (Boyden chamber), proliferation (tritiated thymidine incorporation), alpha-smooth muscle actin expression (ELISA), 3-dimensional collagen gel contraction (floating gel), pro-alpha1(I) collagen mRNA (Northern blotting), total collagen synthesis (tritiated proline incorporation), matrix metalloproteinase activity (gelatin zymography), and TGF-beta(1) release (ELISA) were evaluated. The contribution of eotaxin/CCL11/CCR3 binding on lung fibroblasts was also investigated by neutralizing experiments. CCR3 is constitutively expressed in cultured lung and primary bronchial fibroblasts and colocalizes with specific surface markers for human fibroblasts in lung tissue. Eotaxin/CCL11 selectively modulates fibroblast activities by increasing their proliferation, matrix metalloproteinase 2 activity, and collagen synthesis but not their differentiation into myofibroblasts, contractility in collagen gel, or TGF-beta(1) release. Eotaxin/CCL11 enhances migration of lung fibroblasts in response to nonspecific chemoattractants, and this effect is completely inhibited by anti-CCR3-neutralizing antibodies. These data demonstrate that eotaxin/CCL11 has a direct and selective profibrogenic effect on lung and bronchial fibroblasts, providing a novel mechanism whereby eotaxin/CCL11 can participate in airway remodeling in asthma.

Two Decades of Literature on Self-Directed Learning: A Content Analysis.

ERIC Educational Resources Information Center

Brockett, Ralph G.; Stockdale, Susan L.; Fogerson, Dewey L.; Cox, Barry F.; Canipe, James B.; Chuprina, Larissa A.; Donaghy, Robert C.; Chadwell, Nancy E.

Using a quantitative content analysis approach, a study examined the literature on self direction, or self-directed learning (SDL), that appeared in 14 mainstream adult education journals between 1980-98. The procedure involved classifying, entering, and tallying information on each article through use of an Internet-based program. Results…

The Effects of Self-Directed Teams in an Automotive Manufacturing Environment

ERIC Educational Resources Information Center

Shall, David W.

2010-01-01

This study compares self-directed work structures to more traditional supervised work structures in order to determine if the expenditures and efforts required to implement self-directed work teams are warranted. Multiple internal performance metrics are examined in comparing plant work structures in various degrees of implementation between…

A Framework for Developing Self-Directed Technology Use for Language Learning

ERIC Educational Resources Information Center

Lai, Chun

2013-01-01

Critical to maximizing the potential of technology for learning is enhancing language learners' self-directed use of technology for learning purposes. This study aimed to enhance our understanding of the determinants of self-directed technology use through the construction of a structural equation modelling (SEM) framework of factors and…

p63 Silencing induces reprogramming of cardiac fibroblasts into cardiomyocyte-like cells.

PubMed

Patel, Vivekkumar; Singh, Vivek P; Pinnamaneni, Jaya Pratap; Sanagasetti, Deepthi; Olive, Jacqueline; Mathison, Megumi; Cooney, Austin; Flores, Elsa R; Crystal, Ronald G; Yang, Jianchang; Rosengart, Todd K

2018-04-13

Reprogramming of fibroblasts into induced cardiomyocytes represents a potential new therapy for heart failure. We hypothesized that inactivation of p63, a p53 gene family member, may help overcome human cell resistance to reprogramming. p63 Knockout ( -/- ) and knockdown murine embryonic fibroblasts (MEFs), p63 -/- adult murine cardiac fibroblasts, and human cardiac fibroblasts were assessed for cardiomyocyte-specific feature changes, with or without treatment by the cardiac transcription factors Hand2-Myocardin (HM). Flow cytometry revealed that a significantly greater number of p63 -/- MEFs expressed the cardiac-specific marker cardiac troponin T (cTnT) in culture compared with wild-type (WT) cells (38% ± 11% vs 0.9% ± 0.9%, P < .05). HM treatment of p63 -/- MEFs increased cTnT expression to 74% ± 3% of cells but did not induce cTnT expression in wild-type murine embryonic fibroblasts. shRNA-mediated p63 knockdown likewise yielded a 20-fold increase in cTnT microRNA expression compared with untreated MEFs. Adult murine cardiac fibroblasts demonstrated a 200-fold increase in cTnT gene expression after inducible p63 knockout and expressed sarcomeric α-actinin as well as cTnT. These p63 -/- adult cardiac fibroblasts exhibited calcium transients and electrically stimulated contractions when co-cultured with neonatal rat cardiomyocytes and treated with HM. Increased expression of cTnT and other marker genes was also observed in p63 knockdown human cardiac fibroblasts procured from patients undergoing procedures for heart failure. Downregulation of p63 facilitates direct cardiac cellular reprogramming and may help overcome the resistance of human cells to reprogramming. Copyright © 2018 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Mesenchymal stem cell-derived inflammatory fibroblasts mediate interstitial fibrosis in the aging heart.

PubMed

Trial, JoAnn; Entman, Mark L; Cieslik, Katarzyna A

2016-02-01

Pathologic fibrosis in the aging mouse heart is associated with dysregulated resident mesenchymal stem cells (MSC) arising from reduced stemness and aberrant differentiation into dysfunctional inflammatory fibroblasts. Fibroblasts derived from aging MSC secrete higher levels of 1) collagen type 1 (Col1) that directly contributes to fibrosis, 2) monocyte chemoattractant protein-1 (MCP-1) that attracts leukocytes from the blood and 3) interleukin-6 (IL-6) that facilitates transition of monocytes into myeloid fibroblasts. The transcriptional activation of these proteins is controlled via the farnesyltransferase (FTase)-Ras-Erk pathway. The intrinsic change in the MSC phenotype acquired by advanced age is specific for the heart since MSC originating from bone wall (BW-MSC) or fibroblasts derived from them were free of these defects. The potential therapeutic interventions other than clinically approved strategies based on findings presented in this review are discussed as well. This article is a part of a Special Issue entitled "Fibrosis and Myocardial Remodeling". Copyright © 2015 Elsevier Ltd. All rights reserved.

Wound Repair: Toward Understanding and Integration of Single-Cell and Multicellular Wound Responses

PubMed Central

Sonnemann, Kevin J.; Bement, William M.

2016-01-01

The importance of wound healing to medicine and biology has long been evident, and consequently, wound healing has been the subject of intense investigation for many years. However, several relatively recent developments have added new impetus to wound repair research: the increasing application of model systems; the growing recognition that single cells have a robust, complex, and medically relevant wound healing response; and the emerging recognition that different modes of wound repair bear an uncanny resemblance to other basic biological processes such as morphogenesis and cytokinesis. In this review, each of these developments is described, and their significance for wound healing research is considered. In addition, overlapping mechanisms of single-cell and multicellular wound healing are highlighted, and it is argued that they are more similar than is often recognized. Based on this and other information, a simple model to explain the evolutionary relationships of cytokinesis, single-cell wound repair, multicellular wound repair, and developmental morphogenesis is proposed. Finally, a series of important, but as yet unanswered, questions is posed. PMID:21721944

Self-Directed Professional Development--Hope for Teachers Working in Deprived Environments?

ERIC Educational Resources Information Center

Mushayikwa, Emmanuel; Lubben, Fred

2009-01-01

Self-direction has been identified as a potential key to the success of professional development of teachers, especially those working in deprived environments. This paper develops a model for self-directed professional development using interview data from 55 Zimbabwean A-level Science and Mathematics teachers. It focuses on teachers' decisions…

The Factor Structure of the Self-Directed Learning Readiness Scale (SDLRS).

ERIC Educational Resources Information Center

Wang, Xiaoping; And Others

A study involving teachers and administrators from 16 elementary, middle, and high schools in Tennessee investigated the factorial structure of the Self-Directed Learning Readiness Scale (SDLRS). The SDLRS includes 58 Likert-like items designed to measure the readiness of adult learners to assume self-direction in the learning process. Study…

Motivational Factors in Self-Directed Informal Learning from Online Learning Resources

ERIC Educational Resources Information Center

Song, Donggil; Bonk, Curtis J.

2016-01-01

Learning is becoming more self-directed and informal with the support of emerging technologies. A variety of online resources have promoted informal learning by allowing people to learn on demand and just when needed. It is significant to understand self-directed informal learners' motivational aspects, their learning goals, obstacles, and…

Heart Development, Diseases, and Regeneration　- New Approaches From Innervation, Fibroblasts, and Reprogramming.

PubMed

Ieda, Masaki

2016-09-23

It is well known that cardiac function is tightly controlled by neural activity; however, the molecular mechanism of cardiac innervation during development and the relationship with heart disease remain undetermined. My work has revealed the molecular networks that govern cardiac innervation and its critical roles in heart diseases such as silent myocardial ischemia and arrhythmias. Cardiomyocytes proliferate during embryonic development, but lose their proliferative capacity after birth. Cardiac fibroblasts are a major source of cells during fibrosis and induce cardiac hypertrophy after myocardial injury in the adult heart. Despite the importance of fibroblasts in the adult heart, the role of fibroblasts in embryonic heart development was previously not determined. I demonstrated that cardiac fibroblasts play important roles in myocardial growth and cardiomyocyte proliferation during embryonic development, and I identified key paracrine factors and signaling pathways. In contrast to embryonic cardiomyocytes, adult cardiomyocytes have little regenerative capacity, leading to heart failure and high mortality rates after myocardial infarction. Leveraging the knowledge of developmental biology, I identified cardiac reprogramming factors that can directly convert resident cardiac fibroblasts into cardiomyocytes for heart regeneration. These findings greatly improved our understanding of heart development and diseases, and provide a new strategy for heart regenerative therapy. (Circ J 2016; 80: 2081-2088).

Relationship between the Self-Efficacy and Self-Directed Learning of Adults in Undergraduate Programs

ERIC Educational Resources Information Center

Langshaw, Shelly J.

2017-01-01

In the current adult education environment, self-directed learning (SDL) is becoming a necessary learning characteristic and an academic process of learning to allow adult learners to complete programs and further enhance lifelong learning. The purpose of this quantitative study was to examine the relationship between self-efficacy and SDL in…

Self-assembly of tissue spheroids on polymeric membranes.

PubMed

Messina, Antonietta; Morelli, Sabrina; Forgacs, Gabor; Barbieri, Giuseppe; Drioli, Enrico; De Bartolo, Loredana

2017-07-01

In this study, multicellular tissue spheroids were fabricated on polymeric membranes in order to accelerate the fusion process and tissue formation. To this purpose, tissue spheroids composed of three different cell types, myoblasts, fibroblasts and neural cells, were formed and cultured on agarose and membranes of polycaprolactone (PCL) and chitosan (CHT). Membranes prepared by a phase-inversion technique display different physicochemical, mechanical and transport properties, which can affect the fusion process. The membranes accelerated the fusion process of a pair of spheroids with respect to the inert substrate. In this process, a critical role is played by the membrane properties, especially by their mechanical characteristics and oxygen and carbon dioxide mass transfer. The rate of fusion was quantified and found to be similar for fibroblast, myoblast and neural tissue spheroids on membranes, which completed the fusion within 3 days. These spheroids underwent faster fusion and maturation on PCL membrane than on agarose, the rate of fusion being proportional to the value of oxygen and carbon dioxide permeances and elastic characteristics. Consequently, tissue spheroids on the membranes expressed high biological activity in terms of oxygen uptake, making them more suitable as building blocks in the fabrication of tissues and organs. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

New Directions for Self-Regulation of Learning in Postsecondary Education

ERIC Educational Resources Information Center

Bembenutty, Hefer

2011-01-01

This chapter highlights the major contributions of this volume on self-regulation of learning and provides new directions for cutting-edge theoretical and empirical work that could serve to facilitate self-regulation of learning in postsecondary education. "Self-regulation of learning" refers to learners' beliefs about their ability to engage in…

Garrison's model of self-directed learning: preliminary validation and relationship to academic achievement.

PubMed

Abd-El-Fattah, Sabry M

2010-11-01

In this project, 119 undergraduates responded to a questionnaire tapping three psychological constructs implicated in Garrison's model of self-directed learning: self-management, self-monitoring, and motivation. Mediation analyses showed that these psychological constructs are interrelated and that motivation mediates the relationship between self-management and self-monitoring. Path modeling analyses revealed that self-management and self-monitoring significantly predicted academic achievement over two semesters with self-management being the strongest predictor. Motivation significantly predicted academic achievement over the second semester only. Implications of these findings for self-directed learning and academic achievement in a traditional classroom setting are discussed.

An in-vitro scaffold-free epithelial-fibroblast coculture model for the larynx

PubMed Central

Walimbe, Tanaya; Panitch, Alyssa; Sivasankar, M. Preeti

2017-01-01

Objective Physiologically relevant, well-characterized in vitro vocal fold coculture models are needed to test the effects of various challenges and therapeutics on vocal fold physiology. We characterize a healthy state coculture model, created by using bronchial/tracheal epithelial cells and immortalized vocal fold fibroblasts. We also demonstrate that this model can be induced into a fibroplastic state to overexpress stress fibers using TGFβ1. Method Cell metabolic activity of immortalized human vocal fold fibroblasts incubated in different media combinations were confirmed with MTT assay. Fibroblasts were grown to confluence and primary bronchial/tracheal epithelial cells suspended in coculture media were seeded directly over the base layer of the fibroblasts. Cells were treated with TGFβ1 to induce myofibroblast formation. Cell shape and position was confirmed by live cell tracking, fibrosis was confirmed by probing for α smooth muscle actin (α-SMA) and phenotype was confirmed by immunostaining for vimentin and E-cadherin. Results Fibroblasts retain metabolic activity in coculture epithelial media. Live cell imaging revealed a layer of epithelial cells atop fibroblasts. α-SMA expression was enhanced in TGFβ1 treated cells, confirming that both cell types maintained a healthy phenotype in coculture, and can be induced into overexpressing stress fibers. Vimentin and E-cadherin immunostaining show that cells retain phenotype in coculture. Conclusion These data lay effective groundwork for a functional coculture model that retains the reproducibility necessary to serve as a viable diagnostic and therapeutic screening platform. Level of Evidence NA PMID:27859361

[Relationship between self-directed learning with learning styles and strategies in medical students].

PubMed

Márquez U, Carolina; Fasce H, Eduardo; Pérez V, Cristhian; Ortega B, Javiera; Parra P, Paula; Ortiz M, Liliana; Matus B, Olga; Ibáñez G, Pilar

2014-11-01

Self-directed learning (SDL) skills are particularly important in medical education, considering that physicians should be able to regulate their own learning experiences. To evaluate the relationship between learning styles and strategies and self-directed learning in medical students. One hundred ninety nine first year medical students (120 males) participated in the study. Preparation for Independent Learning (EPAI) scale was used to assess self-direction. Schmeck learning strategies scale and Honey and Alonso (CHAEA) scales were used to evaluate learning styles and strategies. Theoretical learning style and deep processing learning strategy had positive correlations with self-direct learning. Medical students with theoretical styles and low retention of facts are those with greater ability to self-direct their learning. Further studies are required to determine the relationship between learning styles and strategies with SDL in medical students. The acquired knowledge will allow the adjustment of teaching strategies to encourage SDL.

The Organization of Future Translators' Self-Directed Learning at US Universities

ERIC Educational Resources Information Center

Nakonechna, Alyona

2017-01-01

The article deals with studying the peculiarities in the organization of future translators' self-directed learning at US universities. It has been stated that various researches on the problem prove the underestimation of self-directed learning that leads to insufficient professional competency of future translators. It has been found out that to…

Fibroblast growth factor receptor mediates fibroblast-dependent growth in EMMPRIN-depleted head and neck cancer tumor cells.

PubMed

Liu, Zhiyong; Hartman, Yolanda E; Warram, Jason M; Knowles, Joseph A; Sweeny, Larissa; Zhou, Tong; Rosenthal, Eben L

2011-08-01

Head and neck squamous cell carcinoma tumors (HNSCC) contain a dense fibrous stroma which is known to promote tumor growth, although the mechanism of stroma-mediated growth remains unclear. As dysplastic mucosal epithelium progresses to cancer, there is incremental overexpression of extracellular matrix metalloprotease inducer (EMMPRIN) which is associated with tumor growth and metastasis. Here, we present evidence that gain of EMMPRIN expression allows tumor growth to be less dependent on fibroblasts by modulating fibroblast growth factor receptor-2 (FGFR2) signaling. We show that silencing EMMPRIN in FaDu and SCC-5 HNSCC cell lines inhibits cell growth, but when EMMPRIN-silenced tumor cells were cocultured with fibroblasts or inoculated with fibroblasts into severe combined immunodeficient mice, the growth inhibition by silencing EMMPRIN was blunted by the presence of fibroblasts. Coculture experiments showed fibroblast-dependent tumor cell growth occurred via a paracrine signaling. Analysis of tumor gene expression revealed expression of FGFR2 was inversely related to EMMPRIN expression. To determine the role of FGFR2 signaling in EMMPRIN-silenced tumor cells, ligands and inhibitors of FGFR2 were assessed. Both FGF1 and FGF2 enhanced tumor growth in EMMPRIN-silenced cells compared with control vector-transfected cells, whereas inhibition of FGFR2 with blocking antibody or with a synthetic inhibitor (PD173074) inhibited tumor cell growth in fibroblast coculture, suggesting the importance of FGFR2 signaling in fibroblast-mediated tumor growth. Analysis of xenografted tumors revealed that EMMPRIN-silenced tumors had a larger stromal compartment compared with control. Taken together, these results suggest that EMMPRIN acquired during tumor progression promotes fibroblast-independent tumor growth.

Fibroblast growth factor receptor mediates fibroblast-dependent growth in EMMPRIN depleted head and neck cancer tumor cells

PubMed Central

Liu, Zhiyong; Hartman, Yolanda E.; Warram, Jason M.; Knowles, Joseph A.; Sweeny, Larrisa; Zhou, Tong; Rosenthal, Eben L.

2011-01-01

Head and neck squamous cell carcinoma tumors (HNSCC) contain a dense fibrous stroma which is known to promote tumor growth, although the mechanism of stroma mediated growth remains unclear. As dysplastic mucosal epithelium progresses to cancer there is incremental overexpression of extracellular matrix metalloprotease inducer (EMMPRIN) which is associated with tumor growth and metastasis. Here we present evidence that gain of EMMPRIN expression allows tumor growth to be less dependent on fibroblasts by modulating fibroblast growth factor receptor-2 (FGFR2) signaling. We show that silencing EMMPRIN in FaDu and SCC-5 HNSCC cell lines inhibits cell growth, but when EMMPRIN-silenced tumor cells were co-cultured with fibroblasts or inoculated with fibroblasts into SCID mice, the growth inhibition by silencing EMMPRIN was blunted by the presence of fibroblasts. Co-culture experiments demonstrated fibroblast-dependent tumor cell growth occurred via a paracrine signaling. Analysis of tumor gene expression revealed expression of FGFR2 was inversely related to EMMPRIN expression. To determine the role of FGFR2 signaling in EMMPRIN silenced tumor cells, ligands and inhibitors of FGFR2 were assessed. Both FGF1 and FGF2 enhanced tumor growth in EMMPRIN silenced cells compared to control vector transfected cells, while inhibition of FGFR2 with blocking antibody or with a synthetic inhibitor (PD173074) inhibited tumor cell growth in fibroblast co-culture, suggesting the importance of FGFR2 signaling in fibroblast mediated tumor growth. Analysis of xenografted tumors revealed EMMPRIN silenced tumors had a larger stromal compartment compared to control. Taken together, these results suggest that EMMPRIN acquired during tumor progression promotes fibroblast independent tumor growth. PMID:21665938

Servo-integrated patterned media by hybrid directed self-assembly.

PubMed

Xiao, Shuaigang; Yang, Xiaomin; Steiner, Philip; Hsu, Yautzong; Lee, Kim; Wago, Koichi; Kuo, David

2014-11-25

A hybrid directed self-assembly approach is developed to fabricate unprecedented servo-integrated bit-patterned media templates, by combining sphere-forming block copolymers with 5 teradot/in.(2) resolution capability, nanoimprint and optical lithography with overlay control. Nanoimprint generates prepatterns with different dimensions in the data field and servo field, respectively, and optical lithography controls the selective self-assembly process in either field. Two distinct directed self-assembly techniques, low-topography graphoepitaxy and high-topography graphoepitaxy, are elegantly integrated to create bit-patterned templates with flexible embedded servo information. Spinstand magnetic test at 1 teradot/in.(2) shows a low bit error rate of 10(-2.43), indicating fully functioning bit-patterned media and great potential of this approach for fabricating future ultra-high-density magnetic storage media.

Multicellular structures developing during maize microspore culture express endosperm and embryo-specific genes and show different embryogenic potentialities.

PubMed

Massonneau, Agnes; Coronado, Maria-José; Audran, Arthur; Bagniewska, Agnieszka; Mòl, Rafal; Testillano, Pilar S; Goralski, Grzegorz; Dumas, Christian; Risueño, Maria-Carmen; Matthys-Rochon, Elisabeth

2005-07-01

During maize pollen embryogenesis, a range of multicellular structures are formed. Using different approaches, the "nature" of these structures has been determined in terms of their embryogenic potential. In situ molecular identification techniques for gene transcripts and products, and a novel cell tracking system indicated the presence of embryogenic (embryo-like structures, ELS) and non-embryogenic (callus-like structures, CLS) structures that occurred for short periods within the cultures. Some multicellular structures with a compact appearance generated embryos. RT-PCR and fluorescence in situ hybridization (FISH) with confocal microscopy techniques using specific gene markers of the endosperm (ZmESR2, ZmAE3) and embryo (LTP2 and ZmOCL1, ZmOCL3) revealed "embryo" and "endosperm" potentialities in these various multicellular structures present in the cultures. The results presented here showed distinct and specific patterns of gene expression. Altogether, the results demonstrate the presence of different molecules on both embryonic and non-embryonic structures. Their possible roles are discussed in the context of a parallel between embryo/endosperm interactions in planta and embryonic and non-embryonic structure interrelations under in vitro conditions.

Epidermal regulation of dermal fibroblast activity.

PubMed

Garner, W L

1998-07-01

Although the association between delayed burn wound healing and subsequent hypertrophic scar formation is well-established, the mechanism for this relationship is unknown. Unhealed burn wounds lack an epidermis, suggesting a possible regulatory role for the epidermis in controlling dermal fibroblast matrix synthesis. Therefore, we examined the effect of epidermal cells and media conditioned by epidermal cells on fibroblast collagen synthesis and replication. Purified fibroblast and keratinocyte cell strains were developed from discarded normal adult human skin. Conditioned media were created by incubation of cytokine-free and serum-free medium with either confluent fibroblast or keratinocyte cultures for 18 hours (n = 3). Nearly confluent fibroblast cultures were exposed for 48 hours to graded concentrations of either unconditioned medium (control), conditioned medium, or varying numbers of keratinocytes. Replication was quantified by the incorporation of 3H-thymidine. Collagen synthesis was measured by the incorporation of 3H-proline into collagenase-sensitive protein. Data were compared using analysis of variance (ANOVA) and linear regression. Keratinocyte conditioned medium induced a significant increase in replication (n = 3) (p = 0.004) and a decrease in collagen synthesis (n = 6) (p < 0.001). In contrast, neither fibroblast conditioned medium nor control medium had an effect on fibroblast replication or collagen synthesis. Co-culture of fibroblast with a graded number of keratinocytes similarly decreased collagen synthesis (n = 6) (p < 0.001). Dermal fibroblast collagen synthesis appears to be regulated by a soluble keratinocyte product. This result suggests a mechanism for the clinical observation that unhealed burn wounds, which lack the epidermis, demonstrate excess collagen production and scar. Clinical strategies to decrease hypertrophic scar should include an attempt at early wound closure with skin grafting or the application of cultured epithelial

Data-driven modeling reveals cell behaviors controlling self-organization during Myxococcus xanthus development

PubMed Central

Cotter, Christopher R.; Schüttler, Heinz-Bernd; Igoshin, Oleg A.; Shimkets, Lawrence J.

2017-01-01

Collective cell movement is critical to the emergent properties of many multicellular systems, including microbial self-organization in biofilms, embryogenesis, wound healing, and cancer metastasis. However, even the best-studied systems lack a complete picture of how diverse physical and chemical cues act upon individual cells to ensure coordinated multicellular behavior. Known for its social developmental cycle, the bacterium Myxococcus xanthus uses coordinated movement to generate three-dimensional aggregates called fruiting bodies. Despite extensive progress in identifying genes controlling fruiting body development, cell behaviors and cell–cell communication mechanisms that mediate aggregation are largely unknown. We developed an approach to examine emergent behaviors that couples fluorescent cell tracking with data-driven models. A unique feature of this approach is the ability to identify cell behaviors affecting the observed aggregation dynamics without full knowledge of the underlying biological mechanisms. The fluorescent cell tracking revealed large deviations in the behavior of individual cells. Our modeling method indicated that decreased cell motility inside the aggregates, a biased walk toward aggregate centroids, and alignment among neighboring cells in a radial direction to the nearest aggregate are behaviors that enhance aggregation dynamics. Our modeling method also revealed that aggregation is generally robust to perturbations in these behaviors and identified possible compensatory mechanisms. The resulting approach of directly combining behavior quantification with data-driven simulations can be applied to more complex systems of collective cell movement without prior knowledge of the cellular machinery and behavioral cues. PMID:28533367

Question of bone marrow stromal fibroblast traffic

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

Maloney, M.A.; Lamela, R.A.; Patt, H.M.

Bone marrow stromal fibroblasts (CFU-F) normally do not exchange bone marrow sites in vivo. Restitution of the CFU-F after radiation damage is primarily recovery by the local fibroblasts from potentially lethal damage. Migration of stromal fibroblasts from shielded sites to an irradiated site makes a minimal contribution, if any, to CFU-F recovery. Determination of the relative contribution of donor stromal cells in bone marrow transplants by karyotyping the proliferating bone marrow stromal cells in vitro may not reflect the relative distribution of fibroblasts in the marrow. If there is residual damage to the host stromal fibroblasts from treatment before transplantation,more » these cells may not be able to proliferate in vitro. Therefore, an occasional transplanted fibroblast may contribute most of the metaphase figures scored for karyotype.« less

Perimysial fibroblasts of extraocular muscle, as unique as the muscle fibers.

PubMed

Kusner, Linda L; Young, Andrew; Tjoe, Steven; Leahy, Patrick; Kaminski, Henry J

2010-01-01

Extraocular muscle (EOM) has a distinct skeletal muscle phenotype. The hypothesis for the study was that fibroblasts support the unique EOM phenotype and that perimysial fibroblasts derived from EOM have properties that distinguish them from fibroblasts derived from other skeletal muscle. Perimysial fibroblasts from leg muscle (LM-Fibro) and EOM (EOM-Fibro) of mice were derived and maintained in culture. EOM- and LM-Fibro were assessed morphologically and for vimentin, smooth muscle actin, and Thy-1 immunoreactivity. DNA microarray analysis was performed on LM- and EOM-Fibro grown in conditions that support myoblast differentiation. To assess trophic interactions, co-cultures of myoblasts from established cell lines, CL-EOM and CL-LM with, EOM- or LM-Fibro were performed in direct contact and in a permeable filter support culture. The degree of myotube maturation was assessed by the percentage of myotubes with more than three myonuclei per myotube. EOM- and LM-Fibro cells exhibited distinct morphologies. Both cell types proliferated as a monolayer and expressed vimentin. Fifty-five percent (SD 4.4%) of EOM-Fibro were Thy-1 positive compared with only 24% (SD 4.4%) of LM-Fibro. DNA microarray analysis demonstrated differential expression of structural, immune response, and metabolism-related genes between EOM- and LM-Fibro. Co-cultures demonstrated that mature myotube formation in EOM-derived cell lines was supported to a greater extent by EOM-Fibro than by LM-Fibro, compared with CL-EOM grown with LM-Fibro. Fibroblasts from EOM demonstrate distinct properties that distinguish them from leg muscle-derived fibroblasts. The distinct properties of EOM-Fibro may support the unique EOM phenotype and contribute to their differential involvement in disease.

Iranian Clinical Nurses’ Activities for Self-Directed Learning: A Qualitative Study

PubMed Central

Ghiyasvandian, Shahrzad; Malekian, Morteza; Cheraghi, Mohammad Ali

2016-01-01

Background: Clinical nurses need lifelong learning skills for responding to the rapid changes of clinical settings. One of the best strategies for lifelong learning is self-directed learning. The aim of this study was to explore Iranian clinical nurses’ activities for self-directed learning. Methods: In this qualitative study, 23 semi-structured personal interviews were conducted with nineteen clinical nurses working in all four hospitals affiliated to Isfahan Social Security Organization, Isfahan, Iran. Study data were analyzed by using the content analysis approach. The study was conducted from June 2013 to October 2014. Findings: Study participants’ activities for self-directed learning fell into two main categories of striving for knowledge acquisition and striving for skill development. The main theme of the study was ‘Revising personal performance based on intellectual-experiential activities’. Conclusions: Study findings suggest that Iranian clinical nurses continually revise their personal performance by performing self-directed intellectual and experiential activities to acquire expertise. The process of acquiring expertise is a linear process which includes two key steps of knowledge acquisition and knowledge development. In order to acquire and advance their knowledge, nurses perform mental learning activities such as sensory perception, self-evaluation, and suspended judgment step-by-step. Moreover, they develop their skills through doing activities like apprenticeship, masterly performance, and self-regulation. The absolute prerequisite to expertise acquisition is that a nurse needs to follow these two steps in a sequential manner. PMID:26652072

Comparison of human umbilical cord blood-derived mesenchymal stem cells with healthy fibroblasts on wound-healing activity of diabetic fibroblasts.

PubMed

Jung, Jae-A; Yoon, Young-Don; Lee, Hyup-Woo; Kang, So-Ra; Han, Seung-Kyu

2018-02-01

Various types of skin substitutes composed of fibroblasts and/or keratinocytes have been used for the treatment of diabetic ulcers. However, the effects have generally not been very dramatic. Recently, human umbilical cord blood-derived mesenchymal stromal cells (hUCB-MSCs) have been commercialised for cartilage repair as a first cell therapy product using allogeneic stem cells. In a previous pilot study, we reported that hUCB-MSCs have a superior wound-healing capability compared with fibroblasts. The present study was designed to compare the treatment effect of hUCB-MSCs with that of fibroblasts on the diabetic wound healing in vitro. Diabetic fibroblasts were cocultured with healthy fibroblasts or hUCB-MSCs. Five groups were evaluated: group I, diabetic fibroblasts without coculture; groups II and III, diabetic fibroblasts cocultured with healthy fibroblasts or hUCB-MSCs; and groups IV and V, no cell cocultured with healthy fibroblasts or hUCB-MSCs. After a 3-day incubation, cell proliferation, collagen synthesis levels and glycosaminoglycan levels, which are the major contributing factors in wound healing, were measured. As a result, a hUCB-MSC-treated group showed higher cell proliferation, collagen synthesis and glycosaminoglycan level than a fibroblast-treated group. In particular, there were significant statistical differences in collagen synthesis and glycosaminoglycan levels (P = 0·029 and P = 0·019, respectively). In conclusion, these results demonstrate that hUCB-MSCs may have a superior effect to fibroblasts in stimulating diabetic wound healing. © 2017 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Promoting Transfer: Effects of Self-Explanation and Direct Instruction

ERIC Educational Resources Information Center

Rittle-Johnson, Bethany

2006-01-01

Explaining new ideas to oneself can promote transfer, but how and when such self-explanation is effective is unclear. This study evaluated whether self-explanation leads to lasting improvements in transfer success and whether it is more effective in combination with direct instruction or invention. Third- through fifth-grade children (ages 8-11;…

Mass Spectrometry Analyses of Multicellular Tumor Spheroids.

PubMed

Acland, Mitchell; Mittal, Parul; Lokman, Noor A; Klingler-Hoffmann, Manuela; Oehler, Martin K; Hoffmann, Peter

2018-05-01

Multicellular tumor spheroids (MCTS) are a powerful biological in vitro model, which closely mimics the 3D structure of primary avascularized tumors. Mass spectrometry (MS) has established itself as a powerful analytical tool, not only to better understand and describe the complex structure of MCTS, but also to monitor their response to cancer therapeutics. The first part of this review focuses on traditional mass spectrometry approaches with an emphasis on elucidating the molecular characteristics of these structures. Then the mass spectrometry imaging (MSI) approaches used to obtain spatially defined information from MCTS is described. Finally the analysis of primary spheroids, such as those present in ovarian cancer, and the great potential that mass spectrometry analysis of these structures has for improved understanding of cancer progression and for personalized in vitro therapeutic testing is discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Emotional Intelligence and Self-Directed Learning Readiness among College Students Participating in a Leadership Development Program

ERIC Educational Resources Information Center

Radnitzer, Karl David

2010-01-01

The purpose of this study was to investigate possible relationships between self-directed learning readiness and emotional intelligence in a leadership development program and if self-directed learning leads to greater self-directed learning capabilities. Prior research has examined self-directed learning and emotional intelligence but never have…

Three-Dimensional Transgenic Cell Models to Quantify Space Genotoxic Effects

NASA Technical Reports Server (NTRS)

Gonda, S.; Wu, H.; Pingerelli, P.; Glickman, B.

2000-01-01

In this paper we describe a three-dimensional, multicellular tissue-equivalent model, produced in NASA-designed, rotating wall bioreactors using mammalian cells engineered for genomic containment of mUltiple copies of defined target genes for genotoxic assessment. The Rat 2(lambda) fibroblasts (Stratagene, Inc.) were genetically engineered to contain high-density target genes for mutagenesis. Stable three-dimensional, multicellular spheroids were formed when human mammary epithelial cells and Rat 2(lambda) fibroblasts were cocultured on Cytodex 3 Beads in a rotating wall bioreactor. The utility of this spheroidal model for genotoxic assessment was indicated by a linear dose response curve and by results of gene sequence analysis of mutant clones from 400micron diameter spheroids following low-dose, high-energy, neon radiation exposure

A novel role of EMMPRIN/CD147 in transformation of quiescent fibroblasts to cancer-associated fibroblasts by breast cancer cells

PubMed Central

Xu, Jing; Lu, Yang; Qiu, Songbo; Chen, Zhi-Nan; Fan, Zhen

2013-01-01

We tested the novel hypothesis that EMMPRIN/CD147, a transmembrane glycoprotein overexpressed in breast cancer cells, has a previously unknown role in transforming fibroblasts to cancer-associated fibroblasts, and that cancer-associated fibroblasts in turn induce epithelial-to-mesenchymal transition of breast cancer cells. Co-culture of fibroblasts with breast cancer cells or treatment of fibroblasts with breast cancer cell conditioned culture medium or recombinant EMMPRIN/CD147 induced expression of α-SMA in the fibroblasts in an EMMPRIN/CD147-dependent manner and promoted epithelial-to-mesenchymal transition of breast cancer cells and enhanced cell migration potential. These findings support a novel role of EMMPRIN/CD147 in regulating the interaction between cancer and stroma. PMID:23474495

Stretching Fibroblasts Remodels Fibronectin and Alters Cancer Cell Migration

NASA Astrophysics Data System (ADS)

Ao, Mingfang; Brewer, Bryson M.; Yang, Lijie; Franco Coronel, Omar E.; Hayward, Simon W.; Webb, Donna J.; Li, Deyu

2015-02-01

Most investigations of cancer-stroma interactions have focused on biochemical signaling effects, with much less attention being paid to biophysical factors. In this study, we investigated the role of mechanical stimuli on human prostatic fibroblasts using a microfluidic platform that was adapted for our experiments and further developed for both repeatable performance among multiple assays and for compatibility with high-resolution confocal microscopy. Results show that mechanical stretching of normal tissue-associated fibroblasts (NAFs) alters the structure of secreted fibronectin. Specifically, unstretched NAFs deposit and assemble fibronectin in a random, mesh-like arrangement, while stretched NAFs produce matrix with a more organized, linearly aligned structure. Moreover, the stretched NAFs exhibited an enhanced capability for directing co-cultured cancer cell migration in a persistent manner. Furthermore, we show that stretching NAFs triggers complex biochemical signaling events through the observation of increased expression of platelet derived growth factor receptor α (PDGFRα). A comparison of these behaviors with those of cancer-associated fibroblasts (CAFs) indicates that the observed phenotypes of stretched NAFs are similar to those associated with CAFs, suggesting that mechanical stress is a critical factor in NAF activation and CAF genesis.

Self-Directed Learning in the Process of Work: Conceptual Considerations--Empirical Evidences.

ERIC Educational Resources Information Center

Straka, Gerald A.; Schaefer, Cornelia

With reference to the literature on adult self-directed learning, a model termed the "Two-Shell Model of Motivated Self-Directed Learning" was formulated that differentiates sociohistorical environmental conditions, internal conditions, and activities related to four concepts (interest, learning strategies, control, and evaluation). The…

Effect of eosinophils activated with Alternaria on the production of extracellular matrix from nasal fibroblasts.

PubMed

Shin, Seung-Heon; Ye, Mi-Kyung; Choi, Sung-Yong; Kim, Yee-Hyuk

2016-06-01

Eosinophils and fibroblasts are known to play major roles in the pathogenesis of nasal polyps. Fungi are commonly found in nasal secretion and are associated with airway inflammation. To investigate whether activated eosinophils by airborne fungi can influence the production of extracellular matrix (ECM) from nasal fibroblasts. Inferior turbinate and nasal polyp fibroblasts were stimulated with Alternaria or Aspergillus, respectively, for 24 hours and ECM messenger RNA (mRNA) and protein expressions were measured. Eosinophils isolated from healthy volunteers were stimulated with Alternaria or Aspergillus for 4 hours then superoxide, eosinophil peroxidase, and transforming growth factor β1 were measured. Then activated eosinophils were cocultured with nasal fibroblasts for 24 hours, and ECM mRNA expressions were measured. Alternaria strongly enhanced ECM mRNA expression and protein production from nasal fibroblasts. Alternaria also induced the production of superoxide, eosinophil peroxidase, and transforming growth factor β1 from eosinophils, and activated eosinophils enhanced ECM mRNA expression when they were cocultured without the Transwell insert system. Eosinophils activated with Alternaria enhanced ECM mRNA expression from nasal polyp fibroblasts. Alternaria plays an important role in tissue fibrosis in the pathogenesis of nasal polyps by directly or indirectly influencing the production of ECM from nasal fibroblasts. Copyright © 2016 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Costs of injuries due to interpersonal and self-directed violence in Thailand, 2005.

PubMed

Bundhamcharoen, Kanitta; Odton, Patarapan; Mugem, Suwanna; Phulkerd, Sirinya; Dhisayathikom, Kanjana; Brown, David W; Tangcharoensathien, Viroj

2008-06-01

Violence, a serious public health problem in Thailand, remains largely unknown for its economic costs. This study is a national-level economic cost-estimates of injury from interpersonal and self-directed violence for Thailand during 2005 using the World Health Organization-US Centers for Disease Control and Prevention's guidelines. Direct medical costs from self-directed violence totaled 569 million Baht (THB) while the cost of interpersonal violence was THB 1.3 billion. Productivity losses for injuries due to self-directed violence were estimated at THB 12.2 billion and those for interpersonal violence were THB 14.4 billion. The total direct medical cost, thus, accounted for about 4% of Thailand's total health budget while the productivity losses accounted for approximately 0.4% of Thailand s GDP In summary, interpersonal and self-directed violence caused a total loss of 33.8 billion baht for Thailand in 2005. More than 90% of the economic loss was incurred from productivity loss and about four-fifths came from men.

Geometry directed self-selection in the coordination-driven self-assembly of irregular supramolecular polygons.

PubMed

Zheng, Yao-Rong; Northrop, Brian H; Yang, Hai-Bo; Zhao, Liang; Stang, Peter J

2009-05-01

The self-assembly of irregular metallo-supramolecular hexagons and parallelograms has been achieved in a self-selective manner upon mixing 120 degrees unsymmetrical dipyridyl ligands with 60 degrees or 120 degrees organoplatinum acceptors in a 1:1 ratio. The polygons have been characterized using (31)P and (1)H multinuclear NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS) as well as X-ray crystallography. Geometric features of the molecular subunits direct the self-selection process, which is supported by molecular force field computations.

Geometry Directed Self-Selection in the Coordination-Driven Self-Assembly of Irregular Supramolecular Polygons

PubMed Central

Zheng, Yao-Rong; Northrop, Brian H; Yang, Hai-Bo; Zhao, Liang; Stang, Peter J.

2009-01-01

The self-assembly of irregular metallo-supramolecular hexagons and parallelograms has been achieved in a self-selective manner upon mixing 120° unsymmetrical dipyridyl ligands with 60° or 120° organoplatinum acceptors in a 1:1 ratio. The polygons have been characterized using 31P and 1H multinuclear NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS), as well as X-ray crystallography. Geometric features of the molecular subunits direct the self-selection process, which is supported by molecular force field computations. PMID:19348444

Innate Immune Cytokines, Fibroblast Phenotypes, and Regulation of Extracellular Matrix in Lung.

PubMed

Richards, Carl D

2017-02-01

Chronic inflammation can be caused by adaptive immune responses in autoimmune and allergic conditions, driven by a T lymphocyte subset balance (TH1, TH2, Th17, Th22, and/or Treg) and skewed cellular profiles in an antigen-specific manner. However, several chronic inflammatory diseases have no clearly defined adaptive immune mechanisms that drive chronicity. These conditions include those that affect the lung such as nonatopic asthma or idiopathic pulmonary fibrosis comprising significant health problems. The remodeling of extracellular matrix (ECM) causes organ dysfunction, and it is largely generated by fibroblasts as the major cell controlling net ECM. As such, these are potential targets of treatment approaches in the context of ECM pathology. Fibroblast phenotypes contribute to ECM and inflammatory cell accumulation, and they are integrated into chronic disease mechanisms including cancer. Evidence suggests that innate cytokine responses may be critical in nonallergic/nonautoimmune disease, and they enable environmental agent exposure mechanisms that are independent of adaptive immunity. Innate immune cytokines derived from macrophage subsets (M1/M2) and innate lymphoid cell (ILC) subsets can directly regulate fibroblast function. We also suggest that STAT3-activating gp130 cytokines can sensitize fibroblasts to the innate cytokine milieu to drive phenotypes and exacerbate existing adaptive responses. Here, we review evidence exploring innate cytokine regulation of fibroblast behavior.

Web Interface Design Principles for Adults' Self-Directed Learning

ERIC Educational Resources Information Center

Firat, Mehmet; Sakar, A. Nurhan; Kabakci Yurdakul, Isil

2016-01-01

One of the most important features which e-learning tools and environments must possess within the scope of lifelong learning is self-directed learning, which can be considered as a form of self-learning. The aim of this study was to determine, based on the views and recommendations of experts, interface design principles for the development of…

Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) promotes lung fibroblast proliferation, survival and differentiation to myofibroblasts.

PubMed

Hasaneen, Nadia A; Cao, Jian; Pulkoski-Gross, Ashleigh; Zucker, Stanley; Foda, Hussein D

2016-02-17

Idiopathic pulmonary fibrosis (IPF) is a chronic progressively fatal disease. Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) is a glycosylated transmembrane protein that induces the expression of some matrix metalloproteinase (MMP) in neighboring stromal cells through direct epithelial-stromal interactions. EMMPRIN is highly expressed in type II alveolar epithelial cells at the edges of the fibrotic areas in IPF lung sections. However, the exact role of EMMPRIN in IPF is unknown. To determine if EMMPRIN contributes to lung fibroblast proliferation, resistance to apoptosis, and differentiation to myofibroblasts, normal Human lung fibroblasts (NHLF) transiently transfected with either EMMPRIN/GFP or GFP were treated with TGF- β1 from 0 to 10 ng/ml for 48 h and examined for cell proliferation (thymidine incorporation), apoptosis (FACS analysis and Cell Death Detection ELISA assay), cell migration (Modified Boyden chamber) and differentiation to myofibroblasts using Western blot for α-smooth actin of cell lysates. The effect of EMMPRIN inhibition on NHLF proliferation, apoptosis, migration and differentiation to myofibroblasts after TGF- β1 treatment was examined using EMMPRIN blocking antibody. We examined the mechanism by which EMMPRIN induces its effects on fibroblasts by studying the β-catenin/canonical Wnt signaling pathway using Wnt luciferase reporter assays and Western blot for total and phosphorylated β-catenin. Human lung fibroblasts overexpressing EMMPRIN had a significant increase in cell proliferation and migration compared to control fibroblasts. Furthermore, EMMPRIN promoted lung fibroblasts resistance to apoptosis. Lung fibroblasts overexpressing EMMPRIN showed a significantly increased expression of α- smooth muscle actin, a marker of differentiation to myofibroblasts compared to control cells. TGF-β1 increased the expression of EMMPRIN in lung fibroblasts in a dose-dependent manner. Attenuation of EMMPRIN expression with the use of an

Reversine-treated fibroblasts acquire myogenic competence in vitro and in regenerating skeletal muscle.

PubMed

Anastasia, Luigi; Sampaolesi, Maurilio; Papini, Nadia; Oleari, Diego; Lamorte, Giuseppe; Tringali, Cristina; Monti, Eugenio; Galli, Daniela; Tettamanti, Guido; Cossu, Giulio; Venerando, Bruno

2006-12-01

Stem cells hold a great potential for the regeneration of damaged tissues in cardiovascular or musculoskeletal diseases. Unfortunately, problems such as limited availability, control of cell fate, and allograft rejection need to be addressed before therapeutic applications may become feasible. Generation of multipotent progenitors from adult differentiated cells could be a very attractive alternative to the limited in vitro self-renewal of several types of stem cells. In this direction, a recently synthesized unnatural purine, named reversine, has been proposed to induce reversion of adult cells to a multipotent state, which could be then converted into other cell types under appropriate stimuli. Our study suggests that reversine treatment transforms primary murine and human dermal fibroblasts into myogenic-competent cells both in vitro and in vivo. Moreover, this is the first study to demonstrate that plasticity changes arise in primary mouse and human cells following reversine exposure.

Esophageal Squamous Cell Carcinoma Cells Modulate Chemokine Expression and Hyaluronan Synthesis in Fibroblasts*

PubMed Central

Kretschmer, Inga; Freudenberger, Till; Twarock, Sören; Yamaguchi, Yu; Grandoch, Maria; Fischer, Jens W.

2016-01-01

The aim of this study was to characterize the interaction of KYSE-410, an esophageal squamous cell carcinoma cell line, and fibroblasts with respect to the extracellular matrix component hyaluronan (HA) and chemokine expression. KYSE-410 cells induced the mRNA expression of HA synthase 2 (Has2) in normal skin fibroblasts (SF) only in direct co-cultures. Parallel to Has2 mRNA, Has2 antisense RNA (Has2os2) was up-regulated in co-cultures. Knockdown of LEF1, a downstream target of Wnt signaling, abrogated Has2 and Has2os2 induction. After knockdown of Has2 in SF, significantly less α-smooth muscle actin expression was detected in co-cultures. Moreover, it was investigated whether the phenotype of KYSE-410 was affected in co-culture with SF and whether Has2 knockdown in SF had an impact on KYSE-410 cells in co-culture. However, no effects on epithelial-mesenchymal transition markers, proliferation, and migration were detected. In addition to Has2 mRNA, the chemokine CCL5 was up-regulated and CCL11 was down-regulated in SF in co-culture. Furthermore, co-cultures of KYSE-410 cells and cancer-associated fibroblasts (CAF) were investigated. Similar to SF, Has2 and Ccl5 were up-regulated and Ccl11 was down-regulated in CAF in co-culture. Importantly and in contrast to SF, inhibiting HA synthesis by 4-methylumbelliferone abrogated the effect of co-culture on Ccl5 in CAF. Moreover, HA was found to promote adhesion of CD4+ but not CD8+ cells to xenogaft tumor tissues. In conclusion, direct co-culture of esophageal squamous cell carcinoma and fibroblasts induced stromal HA synthesis via Wnt/LEF1 and altered the chemokine profile of stromal fibroblasts, which in turn may affect the tumor immune response. PMID:26699196

Alteration of Skin Properties with Autologous Dermal Fibroblasts

PubMed Central

Thangapazham, Rajesh L.; Darling, Thomas N.; Meyerle, Jon

2014-01-01

Dermal fibroblasts are mesenchymal cells found between the skin epidermis and subcutaneous tissue. They are primarily responsible for synthesizing collagen and glycosaminoglycans; components of extracellular matrix supporting the structural integrity of the skin. Dermal fibroblasts play a pivotal role in cutaneous wound healing and skin repair. Preclinical studies suggest wider applications of dermal fibroblasts ranging from skin based indications to non-skin tissue regeneration in tendon repair. One clinical application for autologous dermal fibroblasts has been approved by the Food and Drug Administration (FDA) while others are in preclinical development or various stages of regulatory approval. In this context, we outline the role of fibroblasts in wound healing and discuss recent advances and the current development pipeline for cellular therapies using autologous dermal fibroblasts. The microanatomic and phenotypic differences of fibroblasts occupying particular locations within the skin are reviewed, emphasizing the therapeutic relevance of attributes exhibited by subpopulations of fibroblasts. Special focus is provided to fibroblast characteristics that define regional differences in skin, including the thick and hairless skin of the palms and soles as compared to hair-bearing skin. This regional specificity and functional identity of fibroblasts provides another platform for developing regional skin applications such as the induction of hair follicles in bald scalp or alteration of the phenotype of stump skin in amputees to better support their prosthetic devices. PMID:24828202

Stimulatory effects of histamine on migration of nasal fibroblasts.

PubMed

Hong, Sung-Moon; Park, Il-Ho; Um, Ji-Young; Shin, Jae-Min; Lee, Heung-Man

2015-10-01

Fibroblast migration is crucial for normal wound repair after sinonasal surgery. Histamine is known to be involved in wound healing by its effects on cell proliferation and migration. This study aimed to determine whether histamine affects the migration of nasal fibroblasts and to investigate the mechanism of action of histamine on nasal fibroblasts. Primary cultures of nasal fibroblasts were established from inferior turbinate samples. Fibroblast migration was evaluated with scratch assays. Cells were treated with histamine and/or histamine receptor-selective antagonists. U-73122 and pertussis toxin, which are selective inhibitors of the lower signaling pathway of H1R and H4R, were used to confirm the modulation of nasal fibroblast migration by histamine. Fibroblast cytoskeletal structures were visualized with immunocytochemistry. Histamine significantly stimulated the migration of nasal fibroblasts. Antagonists selective for HR1 and HR4 significantly reduced nasal fibroblast migration. In immunocytochemical staining, histamine treatment increased membrane ruffling and pyrilamine, diphenhydramine, fexofenadine, and JNJ7777120 decreased histamine-induced membrane ruffling. U-73122 and pertussis toxin also decreased histamine-induced migration of fibroblasts. Histamine maintains its stimulatory effects on fibroblast migration in the presence of mitomycin C, which blocks proliferation of cells. We showed that histamine stimulates fibroblast migration in nasal fibroblasts. This effect appeared to be mediated by HR1 and HR4. However, because fibroblast migration also can be involved in scaring and fibrosis, more research is necessary to determine the effects of antihistamine on wound healing after sinus surgery. © 2015 ARS-AAOA, LLC.

Dissolved Gases and Ice Fracturing During the Freezing of a Multicellular Organism: Lessons from Tardigrades.

PubMed

Kletetschka, Gunther; Hruba, Jolana

2015-01-01

Three issues are critical for successful cryopreservation of multicellular material: gases dissolved in liquid, thermal conductivity of the tissue, and localization of microstructures. Here we show that heat distribution is controlled by the gas amount dissolved in liquids and that when changing the liquid into solid, the dissolved gases either form bubbles due to the absence of space in the lattice of solids and/or are migrated toward the concentrated salt and sugar solution at the cost of amount of heat required to be removed to complete a solid-state transition. These factors affect the heat distribution in the organs to be cryopreserved. We show that the gas concentration issue controls fracturing of ice when freezing. There are volumetric changes not only when changing the liquid into solid (volume increases) but also reduction of the volume when reaching lower temperatures (volume decreases). We discuss these issues parallel with observations of the cryosurvivability of multicellular organisms, tardigrades, and discuss their analogy for cryopreservation of large organs.

Exploring First-Year Undergraduate Medical Students' Self-Directed Learning Readiness to Physiology

ERIC Educational Resources Information Center

Abraham, Reem Rachel; Fisher, Murray; Kamath, Asha; Izzati, T. Aizan; Nabila, Saidatul; Atikah, Nik Nur

2011-01-01

Medical students are expected to possess self-directed learning skills to pursue lifelong learning. Previous studies have reported that the readiness for self-directed learning depends on personal attributes as well as the curriculum followed in institutions. Melaka Manipal Medical College of Manipal University (Karnataka, India) offers a Bachelor…

Meeting Individual Reading Needs Through Individualized, Self-Directed Correction.

ERIC Educational Resources Information Center

Schubert, Delwyn G.

Individualized, self-directed correction in elementary level reading instruction becomes a reality when pupils can work independently with materials that provide instruction and practice in the skills in which they are deficient and can check the accuracy of their own answers. Commercially prepared teacher-directed materials can be converted to…

Nerve growth factor effect on human primary fibroblastic-keratocytes: possible mechanism during corneal healing.

PubMed

Micera, Alessandra; Lambiase, Alessandro; Puxeddu, Ilaria; Aloe, Luigi; Stampachiacchiere, Barbara; Levi-Schaffer, Francesca; Bonini, Sergio; Bonini, Stefano

2006-10-01

In response to corneal injury, cytokines and growth factors play a crucial role by influencing epithelial-stromal interaction during the healing and reparative processes which may resolve in tissue remodeling and fibrosis. While transforming growth factor-beta1 (TGF-beta1) is considered the main profibrogenic modulator of these process, recently the nerve growth factor (NGF) appears as a pleiotropic modulator of wound-healing and inflammatory responses. Interestingly in the cornea, where NGF, trkA(NGFR) and p75(NTR) are expressed by epithelial cells and keratocytes, the NGF eye-drop induces the healing of neurotrophic or autoimmune corneal ulcers. During corneal healing, quiescent keratocytes are replaced by active fibroblast-like keratocytes/myofibroblasts. While the NGF effect on epithelial cells has been investigated, no data are reported for NGF effects on fibroblastic-keratocytes, during corneal healing. NGF, trkA(NGFR) and p75(NTR) were found expressed by fibroblastic-keratocytes. NGF was able to induce fibroblastic-keratocyte differentiation into myofibroblasts, migration, Metalloproteinase-9 expression/activity and contraction of a 3D collagen gel, without affecting their proliferation and collagen production. These data also show a two-directional control of fibroblastic-keratocytes by NGF and TGF-beta1. To sum up, the findings of this study indicate that NGF can modulate some functional activities of fibroblastic-keratocytes, thus substantiating the healing effects of NGF on corneal wound-healing.

Feedback Activation of Basic Fibroblast Growth Factor Signaling via the Wnt/β-Catenin Pathway in Skin Fibroblasts

PubMed Central

Wang, Xu; Zhu, Yuting; Sun, Congcong; Wang, Tao; Shen, Yingjie; Cai, Wanhui; Sun, Jia; Chi, Lisha; Wang, Haijun; Song, Na; Niu, Chao; Shen, Jiayi; Cong, Weitao; Zhu, Zhongxin; Xuan, Yuanhu; Li, Xiaokun; Jin, Litai

2017-01-01

Skin wound healing is a complex process requiring the coordinated behavior of many cell types, especially in the proliferation and migration of fibroblasts. Basic fibroblast growth factor (bFGF) is a member of the FGF family that promotes fibroblast migration, but the underlying molecular mechanism remains elusive. The present RNA sequencing study showed that the expression levels of several canonical Wnt pathway genes, including Wnt2b, Wnt3, Wnt11, T-cell factor 7 (TCF7), and Frizzled 8 (FZD8) were modified by bFGF stimulation in fibroblasts. Enzyme-linked immunosorbent assay (ELISA) analysis also showed that Wnt pathway was activated under bFGF treatment. Furthermore, treatment of fibroblasts with lithium chloride or IWR-1, an inducer and inhibitor of the Wnt signaling pathway, respectively, promoted and inhibited cell migration. Also, levels of cytosolic glycogen synthase kinase 3 beta phosphorylated at serine9 (pGSK3β Ser9) and nuclear β-catenin were increased upon exposure to bFGF. Molecular and biochemical assays indicated that phosphoinositide 3-kinase (PI3K) signaling activated the GSK3β/β-catenin/Wnt signaling pathway via activation of c-Jun N-terminal kinase (JNK), suggesting that PI3K and JNK act at the upstream of β-catenin. In contrast, knock-down of β-catenin delayed fibroblast cell migration even under bFGF stimulation. RNA sequencing analysis of β-catenin knock-down fibroblasts demonstrated that β-catenin positively regulated the transcription of bFGF and FGF21. Moreover, FGF21 treatment activated AKT and JNK, and accelerated fibroblast migration to a similar extent as bFGF does. In addition, ELISA analysis demonstrated that both of bFGF and FGF21 were auto secretion factor and be regulated by Wnt pathway stimulators. Taken together, our analyses define a feedback regulatory loop between bFGF (FGF21) and Wnt signaling acting through β-catenin in skin fibroblasts. PMID:28217097

Brain mechanisms associated with internally directed attention and self-generated thought.

PubMed

Benedek, Mathias; Jauk, Emanuel; Beaty, Roger E; Fink, Andreas; Koschutnig, Karl; Neubauer, Aljoscha C

2016-03-10

Internal cognition like imagination and prospection require sustained internally directed attention and involve self-generated thought. This fMRI study aimed to disentangle the brain mechanisms associated with attention-specific and task-specific processes during internally directed cognition. The direction of attention was manipulated by either keeping a relevant stimulus visible throughout the task, or by masking it, so that the task had to be performed "in the mind's eye". The level of self-directed thought was additionally varied between a convergent and a divergent thinking task. Internally directed attention was associated with increased activation in the right anterior inferior parietal lobe (aIPL), bilateral lingual gyrus and the cuneus, as well as with extended deactivations of superior parietal and occipital regions representing parts of the dorsal attention network. The right aIPL further showed increased connectivity with occipital regions suggesting an active top-down mechanism for shielding ongoing internal processes from potentially distracting sensory stimulation in terms of perceptual decoupling. Activation of the default network was not related to internally directed attention per se, but rather to a higher level of self-generated thought. The findings hence shed further light on the roles of inferior and superior parietal cortex for internally directed cognition.

Triptonide inhibits the pathological functions of gastric cancer-associated fibroblasts.

PubMed

Wang, Zhenfei; Ma, Daguang; Wang, Changshan; Zhu, Zhe; Yang, Yongyan; Zeng, Fenfang; Yuan, Jianlong; Liu, Xia; Gao, Yue; Chen, Yongxia; Jia, Yongfeng

2017-12-01

Direct attacks on tumour cells with chemotherapeutic drugs have the drawbacks of accelerating tumour metastasis and inducing tumour stem cell phenotypes. Inhibition of tumour-associated fibroblasts, which provide nourishment and support to tumour cells, is a novel and promising anti-tumour strategy. However, effective drugs against tumour-associated fibroblasts are currently lacking. In the present study, we explored the possibility of inhibiting the pathological functions of tumour-associated fibroblasts with triptonide. Paired gastric normal fibroblasts (GNFs) and gastric cancer-associated fibroblasts (GCAFs) were obtained from resected tissues. GCAFs showed higher capacities to induce colony formation, migration, and invasion of gastric cancer cells than GNFs. Triptonide treatment strongly inhibited the colony formation-, migration-, and invasion-promoting capacities of GCAFs. The expression of microRNA-301a was higher and that of microRNA-149 was lower in GCAFs than in GNFs. Triptonide treatment significantly down-regulated microRNA-301a expression and up-regulated microRNA-149 expression in GCAFs. Re-establishment of microRNA expression balance increased the production and secretion of tissue inhibitor of metalloproteinase 2, a tumour suppressive factor, and suppressed the production and secretion of IL-6, an oncogenic factor, in GCAFs. Moreover, triptonide treatment abolished the ability of GCAFs to induce epithelial-mesenchymal transition in gastric cancer cells. These results indicate that triptonide inhibits the malignancy-promoting capacity of GCAFs by correcting abnormalities in microRNA expression. Thus, triptonide is a promisingly therapeutic agent for gastric cancer treatment, and traditional herbs may be a valuable source for developing new drugs that can regulate the tumour microenvironment. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Cardiac Fibroblast: The Renaissance Cell

PubMed Central

Souders, Colby A.; Bowers, Stephanie L.K.; Baudino, Troy A.

2012-01-01

The permanent cellular constituents of the heart include cardiac fibroblasts, myocytes, endothelial cells and vascular smooth muscle cells. Previous studies have demonstrated that there are undulating changes in cardiac cell populations during embryonic development, through neonatal development and into the adult. Transient cell populations include lymphocytes, mast cells and macrophages, which can interact with these permanent cell types to affect cardiac function. It has also been observed that there are marked differences in the makeup of the cardiac cell populations depending on the species, which may be important when examining myocardial remodeling. Current dogma states that the fibroblast makes up the largest cell population of the heart; however, this appears to vary for different species, especially mice. Cardiac fibroblasts play a critical role in maintaining normal cardiac function, as well as in cardiac remodeling during pathological conditions such as myocardial infarct and hypertension. These cells have numerous functions, including synthesis and deposition of extracellular matrix, cell-cell communication with myocytes, cell-cell signaling with other fibroblasts, as well as with endothelial cells. These contacts affect the electrophysiological properties, secretion of growth factors and cytokines, as well as potentiating blood vessel formation. While a plethora of information is known about several of these processes, relatively little is understood about fibroblasts and their role in angiogenesis during development or cardiac remodeling. In this review we provide insight into the various properties of cardiac fibroblasts that helps illustrate their importance in maintaining proper cardiac function, as well as their critical role in the remodeling heart. PMID:19959782

Neural correlates of direct and reflected self-appraisals in adolescents and adults: when social perspective-taking informs self-perception.

PubMed

Pfeifer, Jennifer H; Masten, Carrie L; Borofsky, Larissa A; Dapretto, Mirella; Fuligni, Andrew J; Lieberman, Matthew D

2009-01-01

Classic theories of self-development suggest people define themselves in part through internalized perceptions of other people's beliefs about them, known as reflected self-appraisals. This study uses functional magnetic resonance imaging to compare the neural correlates of direct and reflected self-appraisals in adolescence (N = 12, ages 11-14 years) and adulthood (N = 12, ages 23-30 years). During direct self-reflection, adolescents demonstrated greater activity than adults in networks relevant to self-perception (medial prefrontal and parietal cortices) and social-cognition (dorsomedial prefrontal cortex, temporal-parietal junction, and posterior superior temporal sulcus), suggesting adolescent self-construals may rely more heavily on others' perspectives about the self. Activity in the medial fronto-parietal network was also enhanced when adolescents took the perspective of someone more relevant to a given domain.

Self-Direction in On-Line Language Learning

ERIC Educational Resources Information Center

Rappel, L.

2017-01-01

This paper presents design based research on the role of self-direction in online learning by exploring elements of both individual and collective engagement as significant aspects of learning. By making the claim that online instruction draws on autonomous and social aspects of learning, this paper examines how online teaching environments are…

The Relationship between Transformational Leadership and Knowledge Workers' Self-Directed Learning Readiness

ERIC Educational Resources Information Center

Aparicio, Ricardo Antonio

2013-01-01

The rapid pace of change for knowledge workers competing globally necessitates ongoing continuous learning. Increasingly, knowledge workers will need to be ready--willing and able--to engage in self-directed learning. This makes it important to understand what factors in the work environment might be related to the self-directed learning…

Occludin confers adhesiveness when expressed in fibroblasts.

PubMed

Van Itallie, C M; Anderson, J M

1997-05-01

Occludin is an integral membrane protein specifically associated with tight junctions. Previous studies suggest it is likely to function in forming the intercellular seal. In the present study, we expressed occludin under an inducible promotor in occludin-null fibroblasts to determine whether this protein confers intercellular adhesion. When human occludin is stably expressed in NRK and Rat-1 fibroblasts, which lack endogenous occludin and tight junctions but do have well developed ZO-1-containing adherens-like junctions, occludin colocalizes with ZO-1 to points of cell-cell contact. In contrast, L-cell fibroblasts which lack cadherin-based adherens junctions, target neither ZO-1 nor occludin to sites of cell contact. Occludin-induced adhesion was next quantified using a suspended cell assay. In NRK and Rat-1 cells, occludin expression induces adhesion in the absence of calcium, thus independent of cadherin-cadherin contacts. In contrast, L-cells are nonadhesive in this assay and show no increase in adhesion after induction of occludin expression. Binding of an antibody to the first of the putative extracellular loops of occludin confirmed that this sequence was exposed on the cell surface, and synthetic peptides containing the amino acid sequence of this loop inhibit adhesion induced by occludin expression. These results suggest that the extracellular surface of occludin is directly involved in cell-cell adhesion and the ability to confer adhesiveness correlates with the ability to colocalize with its cytoplasmic binding protein, ZO-1.

Cell-cell bioelectrical interactions and local heterogeneities in genetic networks: a model for the stabilization of single-cell states and multicellular oscillations.

PubMed

Cervera, Javier; Manzanares, José A; Mafe, Salvador

2018-04-04

Genetic networks operate in the presence of local heterogeneities in single-cell transcription and translation rates. Bioelectrical networks and spatio-temporal maps of cell electric potentials can influence multicellular ensembles. Could cell-cell bioelectrical interactions mediated by intercellular gap junctions contribute to the stabilization of multicellular states against local genetic heterogeneities? We theoretically analyze this question on the basis of two well-established experimental facts: (i) the membrane potential is a reliable read-out of the single-cell electrical state and (ii) when the cells are coupled together, their individual cell potentials can be influenced by ensemble-averaged electrical potentials. We propose a minimal biophysical model for the coupling between genetic and bioelectrical networks that associates the local changes occurring in the transcription and translation rates of an ion channel protein with abnormally low (depolarized) cell potentials. We then analyze the conditions under which the depolarization of a small region (patch) in a multicellular ensemble can be reverted by its bioelectrical coupling with the (normally polarized) neighboring cells. We show also that the coupling between genetic and bioelectric networks of non-excitable cells, modulated by average electric potentials at the multicellular ensemble level, can produce oscillatory phenomena. The simulations show the importance of single-cell potentials characteristic of polarized and depolarized states, the relative sizes of the abnormally polarized patch and the rest of the normally polarized ensemble, and intercellular coupling.

Coxsackievirus B3 induces the formation of autophagosomes in cardiac fibroblasts both in vitro and in vivo

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

Zhai, Xia, E-mail: zhai_xia_cool@126.com; Qin, Ying, E-mail: qinyinggaofeng@163.com; Chen, Yang, E-mail: cy_hmu@126.com

Coxsackievirus group B (CVB) is one of the common pathogens that cause myocarditis and cardiomyopathy. Evidence has shown that CVB replication in cardiomyocytes is responsible for the damage and loss of cardiac muscle and the dysfunction of the heart. However, it remains largely undefined how CVB would directly impact cardiac fibroblasts, the most abundant cells in human heart. In this study, cardiac fibroblasts were isolated from Balb/c mice and infected with CVB type 3 (CVB3). Increased double-membraned, autophagosome-like vesicles in the CVB3-infected cardiac fibroblasts were observed with electron microscope. Punctate distribution of LC3 and increased level of LC3-II were alsomore » detected in the infected cardiac fibroblasts. Furthermore, we observed that the expression of pro-inflammatory cytokines, IL-6 and TNF-α, was increased in the CVB3-infected cardiac fibroblasts, while suppressed autophagy by 3-MA and Atg7-siRNA inhibited cytokine expression. Consistent with the in vitro findings, increased formation of autophagosomes was observed in the cardiac fibroblasts of Balb/c mice infected with CVB3. In conclusion, our data demonstrated that cardiac fibroblasts respond to CVB3 infection with the formation of autophagosomes and the release of the pro-inflammatory cytokines. These results suggest that the autophagic response of cardiac fibroblasts may play a role in the pathogenesis of myocarditis caused by CVB3 infection. - Highlights: • CVB3 replication induced autophagosome assembly in primary cardiac fibroblasts. • Both IL-6 and TNF-α in cardiac fibroblasts infected by CVB3 were increased. • IL-6 and TNF-α were reduced in cardiac fibroblasts when autophagy was inhibited. • Autophagosome assembly in cardiac fibroblasts of CVB-infected mice was increased.« less

[Association between self-directed learning behaviors, socio-demographic and academic variables among medical students].

PubMed

Fasce H, Eduardo; Ortega B, Javiera; Pérez V, Cristhian; Márquez U, Carolina; Parra P, Paula; Ortiz M, Liliana; Matus, Olga

2013-09-01

Medical education must encourage autonomous learning behaviors among students. However the great income profile disparity among university students may influence their capacity to acquire such skills. To assess the association between self-directed learning, socio-demographic and academic variables. The self-directed learning readiness scale was applied to 202 medical students aged between 17 and 25 years (64% males). Simultaneously information about each surveyed participant was obtained from the databases of the medical school. There is an association between socio-demographic and academic variables with the general scale of self-directed learning and the subscales learning planning and willingness to learn. Participants coming from municipal schools have a greater willingness to learn than their counterparts coming from subsidized and private schools. High school grades are related to self-directed learning and the subscales learning planning and self-assessment. Among the surveyed medical students, there is a relationship between self-directed learning behaviors, the type of school where they come from and the grades that they obtained during high school.

Focal Adhesion Kinase Regulates Fibroblast Migration via Integrin beta-1 and Plays a Central Role in Fibrosis

PubMed Central

Zhao, Xue-Ke; Cheng, Yiju; Liang Cheng, Ming; Yu, Lei; Mu, Mao; Li, Hong; Liu, Yang; Zhang, Baofang; Yao, Yumei; Guo, Hui; Wang, Rong; Zhang, Quan

2016-01-01

Lung fibrosis is a major medical problem for the aging population worldwide. Fibroblast migration plays an important role in fibrosis. Focal Adhesion Kinase (FAK) senses the extracellular stimuli and initiates signaling cascades that promote cell migration. This study first examined the dose and time responses of FAK activation in human lung fibroblasts treated with platelet derived growth factor BB (PDGF-BB). The data indicate that FAK is directly recruited by integrin β1 and the subsequent FAK activation is required for fibroblast migration on fibronectin. In addition, the study has identified that α5β1 and α4β1 are the major integrins for FAK-mediated fibroblast migration on fibronect. In contrast, integrins αvβ3, αvβ6, and αvβ8 play a minor but distinct role in fibroblast migration on fibronectin. FAK inhibitor significantly reduces PDGF-BB stimulated fibroblast migration. Importantly, FAK inhibitor protects bleomycin-induced lung fibrosis in mice. FAK inhibitor blocks FAK activation and significantly reduces signaling cascade of fibroblast migration in bleomycin-challenged mice. Furthermore, FAK inhibitor decreases lung fibrotic score, collagen accumulation, fibronectin production, and myofibroblast differentiation in in bleomycin-challenged mice. These data demonstrate that FAK mediates fibroblast migration mainly via integrin β1. Furthermore, the findings suggest that targeting FAK signaling is an effective therapeutic strategy against fibrosis. PMID:26763945

The fibroblast surface markers FAP, anti-fibroblast, and FSP are expressed by cells of epithelial origin and may be altered during epithelial-to-mesenchymal transition.

PubMed

Kahounová, Zuzana; Kurfürstová, Daniela; Bouchal, Jan; Kharaishvili, Gvantsa; Navrátil, Jiří; Remšík, Ján; Šimečková, Šárka; Študent, Vladimír; Kozubík, Alois; Souček, Karel

2017-04-06

The identification of fibroblasts and cancer-associated fibroblasts from human cancer tissue using surface markers is difficult, especially because the markers used currently are usually not expressed solely by fibroblasts, and the identification of fibroblast-specific surface molecules is still under investigation. It was aimed to compare three commercially available antibodies in the detection of different surface epitopes of fibroblasts (anti-fibroblast, fibroblast activation protein α, and fibroblast surface protein). The specificity of their expression, employing fibroblast cell lines and tumor-derived fibroblasts from breast and prostate tissues was investigated. Both the established fibroblast cell line HFF-1 and ex vivo primary fibroblasts isolated from breast and prostate cancer tissues expressed the tested surface markers to different degrees. Surprisingly, those markers were expressed also by permanent cell lines of epithelial origin, both benign and cancer-derived (breast-cell lines MCF 10A, HMLE and prostate-cell lines BPH-1, DU 145, and PC-3). The expression of fibroblast activation protein α increased on the surface of previously described models of epithelial cells undergoing epithelial-to-mesenchymal transition in response to treatment with TGF-β1. To prove the co-expression of the fibroblast markers on cells of epithelial origin, we used freshly dissociated human prostate and breast cancer tissues. The results confirmed the co-expression of anti-fibroblast and fibroblast surface protein on CD31/CD45-negative/EpCAM-positive epithelial cells. In summary, our data support the findings that the tested fibroblast markers are not fibroblast specific and may be expressed also by cells of epithelial origin (e.g., cells undergoing EMT). Therefore, the expression of these markers should be interpreted with caution, and the combination of several epitopes for both positive (anti-fibroblast or fibroblast activation protein α) and negative (Ep

Gender Differences in Emotional Risk for Self- and Other-Directed Violence among Externalizing Adults

PubMed Central

Sadeh, Naomi; Javdani, Shabnam; Finy, M. Sima; Verona, Edelyn

2012-01-01

OBJECTIVE Women and men generally differ in how frequently they engage in other-and self-directed physical violence and may show distinct emotional risk factors for engagement in these high-impact behaviors. To inform this area, we investigated gender differences in the relationship of emotional tendencies (i.e., anger, hostility, and anhedonic depression) that may represent risk for other-directed (i.e., physical fighting, attacking others unprovoked) and self-directed violence (i.e., self-injury, suicide attempts). METHOD The ethnically-diverse sample consisted of 372 adults (252 men and 120 women ages 18–55) with a history of criminal convictions. Facets of emotional risk assessed with the Aggression Questionnaire (Buss & Warren, 2000) and Mood and Anxiety Symptom Questionnaire (Watson et al., 1995) were entered simultaneously as explanatory variables in regression analyses to investigate their unique contributions to other- and self-directed physical violence in men and women. RESULTS Analyses revealed anhedonic depressive tendencies negatively predicted other-directed violence and positively predicted self-directed violence in both men and women, consistent with a model of depression in which aggression is turned inwards (Henriksson et al., 1993). Gender differences, however, emerged for the differential contributions of anger and hostility to other-and self-directed violence. Specifically, trait anger (i.e., difficulty controlling one’s temper) was associated with other-directed violence selectively in men, whereas trait hostility (i.e., suspiciousness and alienation) was associated with self- and other-directed violence among women. CONCLUSIONS The divergent findings for trait anger and hostility underscore the need to examine gender-specific risk factors for physical violence to avoid excluding potentially useful clinical features of these mental health outcomes. PMID:21261437

Chemotherapy activates cancer-associated fibroblasts to maintain colorectal cancer-initiating cells by IL-17A

PubMed Central

Lotti, Fiorenza; Jarrar, Awad M.; Pai, Rish K.; Hitomi, Masahiro; Lathia, Justin; Mace, Adam; Gantt, Gerald A.; Sukhdeo, Kumar; DeVecchio, Jennifer; Vasanji, Amit; Leahy, Patrick; Hjelmeland, Anita B.

2013-01-01

Many solid cancers display cellular hierarchies with self-renewing, tumorigenic stemlike cells, or cancer-initiating cells (CICs) at the apex. Whereas CICs often exhibit relative resistance to conventional cancer therapies, they also receive critical maintenance cues from supportive stromal elements that also respond to cytotoxic therapies. To interrogate the interplay between chemotherapy and CICs, we investigated cellular heterogeneity in human colorectal cancers. Colorectal CICs were resistant to conventional chemotherapy in cell-autonomous assays, but CIC chemoresistance was also increased by cancer-associated fibroblasts (CAFs). Comparative analysis of matched colorectal cancer specimens from patients before and after cytotoxic treatment revealed a significant increase in CAFs. Chemotherapy-treated human CAFs promoted CIC self-renewal and in vivo tumor growth associated with increased secretion of specific cytokines and chemokines, including interleukin-17A (IL-17A). Exogenous IL-17A increased CIC self-renewal and invasion, and targeting IL-17A signaling impaired CIC growth. Notably, IL-17A was overexpressed by colorectal CAFs in response to chemotherapy with expression validated directly in patient-derived specimens without culture. These data suggest that chemotherapy induces remodeling of the tumor microenvironment to support the tumor cellular hierarchy through secreted factors. Incorporating simultaneous disruption of CIC mechanisms and interplay with the tumor microenvironment could optimize therapeutic targeting of cancer. PMID:24323355

Directed block copolymer self-assembly implemented via surface-embedded electrets

NASA Astrophysics Data System (ADS)

Wu, Mei-Ling; Wang, Dong; Wan, Li-Jun

2016-02-01

Block copolymer (BCP) nanolithography is widely recognized as a promising complementary approach to circumvent the feature size limits of conventional photolithography. The directed self-assembly of BCP thin film to form ordered nanostructures with controlled orientation and localized pattern has been the key challenge for practical nanolithography applications. Here we show that BCP nanopatterns can be directed on localized surface electrets defined by electron-beam irradiation to realize diverse features in a simple, effective and non-destructive manner. Charged electrets can generate a built-in electric field in BCP thin film and induce the formation of perpendicularly oriented microdomain of BCP film. The electret-directed orientation control of BCP film can be either integrated with mask-based patterning technique or realized by electron-beam direct-writing method to fabricate microscale arbitrary lateral patterns down to single BCP cylinder nanopattern. The electret-directed BCP self-assembly could provide an alternative means for BCP-based nanolithography, with high resolution.

The Paramyxea Levine 1979: An original example of evolution towards multicellularity

NASA Astrophysics Data System (ADS)

Desportes, Isabelle

1984-03-01

The Paramyxea are parasitic in marine invertebrates. Their development is a sporulation involving the differentiation within a stem cell of several sporonts which produce spores made of cells enclosed inside each other. Three genera are recognized according to the number of spores and sporal cells, and the taxonomic position of the host (Polychaeta, Mollusca, Crustacea). The Paramyxea exhibit both protistan and metazoan characters. Their nine singlets centrioles are observed in different Protoctists whereas the fact that their sporal cells acquire distinctive cytological features may be interpreted as an evolution towards multicellularity.

Neural Correlates of Direct and Reflected Self-Appraisals in Adolescents and Adults: When Social Perspective-Taking Informs Self-Perception

PubMed Central

Pfeifer, Jennifer H.; Masten, Carrie L.; Borofsky, Larissa A.; Dapretto, Mirella; Fuligni, Andrew J.; Lieberman, Matthew D.

2011-01-01

Classic theories of self-development suggest people define themselves in part through internalized perceptions of other people’s beliefs about them, known as reflected self-appraisals. This study uses functional magnetic resonance imaging to compare the neural correlates of direct and reflected self-appraisals in adolescence (N = 12, ages 11–14 years) and adulthood (N = 12, ages 23–30 years). During direct self-reflection, adolescents demonstrated greater activity than adults in networks relevant to self-perception (medial prefrontal and parietal cortices) and social-cognition (dorsomedial prefrontal cortex, temporal–parietal junction, and posterior superior temporal sulcus), suggesting adolescent self-construals may rely more heavily on others’ perspectives about the self. Activity in the medial fronto-parietal network was also enhanced when adolescents took the perspective of someone more relevant to a given domain. PMID:19630891

FSP1+ fibroblast subpopulation is essential for the maintenance and regeneration of medullary thymic epithelial cells

PubMed Central

Sun, Lina; Sun, Chenming; Liang, Zhanfeng; Li, Hongran; Chen, Lin; Luo, Haiying; Zhang, Hongmei; Ding, Pengbo; Sun, Xiaoning; Qin, Zhihai; Zhao, Yong

2015-01-01

Thymic epithelial cells (TECs) form a 3-dimentional network supporting thymocyte development and maturation. Besides epithelium and thymocytes, heterogeneous fibroblasts are essential components in maintaining thymic microenvironments. However, thymic fibroblast characteristics, development and function remain to be determined. We herein found that thymic non-hematopoietic CD45-FSP1+ cells represent a unique Fibroblast specific protein 1 (FSP1)—fibroblast-derived cell subset. Deletion of these cells in FSP1-TK transgenic mice caused thymus atrophy due to the loss of TECs, especially mature medullary TECs (MHCIIhigh, CD80+ and Aire+). In a cyclophosphamide-induced thymus injury and regeneration model, lack of non-hematopoietic CD45-FSP1+ fibroblast subpopulation significantly delayed thymus regeneration. In fact, thymic FSP1+ fibroblasts released more IL-6, FGF7 and FSP1 in the culture medium than their FSP1- counterparts. Further experiments showed that the FSP1 protein could directly enhance the proliferation and maturation of TECs in the in vitro culture systems. FSP1 knockout mice had significantly smaller thymus size and less TECs than their control. Collectively, our studies reveal that thymic CD45-FSP1+ cells are a subpopulation of fibroblasts, which is crucial for the maintenance and regeneration of TECs especially medullary TECs through providing IL-6, FGF7 and FSP1. PMID:26445893

Investigating the Relationship Between Self-Directed Learning Readiness and Time Management Skills in Turkish Undergraduate Nursing Students.

PubMed

Ertuğ, Nurcan; Faydali, Saide

The aims of this study were to determine self-directed learning and time management skills of undergraduate nursing students and to investigate the relationship between the concepts. The use of self-directed learning has increased as an educational strategy in recent years. This descriptive and correlational study was conducted with 383 undergraduate nursing students in Turkey. Data were collected using a sociodemographic questionnaire, the Self-Directed Learning Readiness Scale, and Time Management Questionnaire. Mean scores were as follows: self-directed learning readiness, 159.12 (SD = 20.8); time management, 87.75 (SD = 12.1). A moderate positive correlation was found between self-directed learning readiness and time management values. Time management scores were 78.42 when self-directed learning readiness was ≤149 and 90.82 when self-directed learning readiness was ≥ 150, with a statistically significant difference (p = .000). Level of self-directed learning and academic achievement were higher in students who managed their time well.

Customization and design of directed self-assembly using hybrid prepatterns

NASA Astrophysics Data System (ADS)

Cheng, Joy; Doerk, Gregory S.; Rettner, Charles T.; Singh, Gurpreet; Tjio, Melia; Truong, Hoa; Arellano, Noel; Balakrishnan, Srinivasan; Brink, Markus; Tsai, Hsinyu; Liu, Chi-Chun; Guillorn, Michael; Sanders, Daniel P.

2015-03-01

Diminishing error tolerance renders the customization of patterns created through directed self-assembly (DSA) extremely challenging at tighter pitch. A self-aligned customization scheme can be achieved using a hybrid prepattern comprising both organic and inorganic regions that serves as a guiding prepattern to direct the self-assembly of the block copolymers as well as a cut mask pattern for the DSA arrays aligned to it. In this paper, chemoepitaxy-based self-aligned customization is demonstrated using two types of organic-inorganic prepatterns. CHEETAH prepattern for "CHemoepitaxy Etch Trim using a self-Aligned Hardmask" of preferential hydrogen silsesquioxane (HSQ, inorganic resist), non-preferential organic underlayer is fabricated using electron beam lithography. Customized trench or hole arrays can be achieved through co-transfer of DSA-formed arrays and CHEETAH prepattern. Herein, we also introduce a tone-reversed version called reverse-CHEETAH (or rCHEETAH) in which customized line segments can be achieved through co-transfer of DSA-formed arrays formed on a prepattern wherein the inorganic HSQ regions are nonpreferential and the organic regions are PMMA preferential. Examples of two-dimensional self-aligned customization including 25nm pitch fin structures and an 8-bar "IBM" illustrate the versatility of this customization scheme using rCHEETAH.

On the teaching model of website-based collaborated self-directed study

NASA Astrophysics Data System (ADS)

Jing, Zhihua; Zeng, Yingxiong; Wen, Chunyu

2011-12-01

Based on the theory of collaborated self-directed study and the strengths of modern education technology, the study explores application of websites for collaborated self-directed college English learning. It introduces the characteristics and functions of the website developed to assist college English teaching in China. It also points out the problems currently existing among teachers and students, and puts forward some suggestions and strategies for the improvement of the application of the website.

Fibroblastic connective tissue nevus.

PubMed

Velez, Moises J; Billings, Steven D; Weaver, Joshua A

2016-01-01

Fibroblastic connective tissue nevus (FCTN) is a newly recognized, benign cutaneous mesenchymal lesion of fibroblasts/myofibroblastic lineage, which expands the classification of connective tissue nevi. We present three cases of FCTN and discuss significant clinical, morphologic and immunophenotypic overlap with dermatomyofibroma. Our cases were from young women, aged 32, 24 and 10, and presented as 1.2 and 1 cm nodules on the posterior neck and right upper flank, respectively while presenting as a linear plaque of the right posterior thigh in the latter case. The lesions showed a poorly circumscribed proliferation of hypercellular spindle cells arranged in short to longer intersecting fascicles entrapping adnexal structures. Superficial adipose tissue was also entrapped in one case. The spindle cells had fibroblastic features with pale eosinophilic cytoplasmic extensions and inconspicuous nucleoli. The spindle cells were positive for CD34 in two cases. One case was negative for CD34, smooth muscle actin (SMA), desmin and S100. The overall features were consistent with a diagnosis of FCTN. In two cases, we further elucidated the fibroblastic differentiation of the spindle cells in FCTN with electron microscopy, which has not been previously described. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Perspectives of self-direction: a systematic review of key areas contributing to service users' engagement and choice-making in self-directed disability services and supports.

PubMed

Lakhani, Ali; McDonald, Donna; Zeeman, Heidi

2018-05-01

Self-directed disability support policies aim to encourage greater choice and control for service users in terms of the health and social care they receive. The proliferation of self-directed disability support policies throughout the developed world has resulted in a growing amount of research exploring the outcomes for service users, and their families and carers. Our understanding of the issues faced by people with disabilities, particularly how they make health and social care decisions and the key areas that determine their engagement with service providers within a self-directed environment is limited. A synthesis of research is timely and can provide knowledge for service users and health and social care support providers to ensure their successful participation. A systematic review guided by the PRISMA approach explored (i) the key areas determining service users' engagement with self-directed disability services and supports, and (ii) how service users make informed decisions about providers. In October 2014 and April 2016, three databases - MEDLINE, CINAHL and Web of Science - were searched for research and review articles. Eighteen sources met the search criteria. Findings were mapped into either: key areas determining service user engagement, or service users' informed decision-making. Findings concerning key areas determining engagement fell into three themes - personal responsibility for budgeting, personalised approaches, and a cultural shift in practice and delivery among service providers. Findings about decision-making yielded two themes - supporting informed decision-making and inhibiting informed decision-making. Literature suggests that self-directed models of care may provide service users with increased control over the services that they receive. Increased control for some service users and their families requires independent external decision-making support, particularly around the domains of budgeting, planning and hiring. Future research

The influence of genistein on free radicals in normal dermal fibroblasts and keloid fibroblasts examined by EPR spectroscopy.

PubMed

Jurzak, Magdalena; Ramos, Paweł; Pilawa, Barbara

2017-01-01

Normal and keloid fibroblasts were examined using X-band (9.3 GHz) electron paramagnetic resonance spectroscopy. The effect of genistein on the concentration of free radicals in both normal dermal and keloid fibroblasts after ultraviolet irradiation was investigated. The highest concentration of free radicals was seen in keloid fibroblasts, with normal fibroblasts containing a lower concentration. The concentration of free radicals in both normal and keloid fibroblasts was altered in a concentration-dependent manner by the presence of genistein. The change in intra-cellular free radical concentration after the ultraviolet irradiation of both normal and keloid fibroblasts is also discussed. The antioxidant properties of genistein, using its 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging activity as a model, were tested, and the effect of ultraviolet irradiation on its interaction with free radicals was examined. The electron paramagnetic resonance spectra of DPPH showed quenching by genistein. The interaction of genistein with DPPH free radicals in the absence of ultraviolet irradiation was shown to be slow, but this interaction was much faster under ultraviolet irradiation. Ultraviolet irradiation enhanced the free radical-scavenging activity of genistein.

Relationship between Health Literacy and Self-Directed Learning Readiness of Older Adults

ERIC Educational Resources Information Center

Dennis, Robin Justice

2017-01-01

The primary purpose of this study was to determine if the health literacy level of older adults, age 65 and older, and the self-directed learning readiness score were correlated. After data cleaning, the number of cases was below the recommended rule of thumb. Deletion of cases indicated by the analyst of the self-directed learning readiness score…

IL-11 facilitates a novel connection between RA joint fibroblasts and endothelial cells.

PubMed

Elshabrawy, Hatem A; Volin, Michael V; Essani, Abdul B; Chen, Zhenlong; McInnes, Iain B; Van Raemdonck, Katrien; Palasiewicz, Karol; Arami, Shiva; Gonzalez, Mark; Ashour, Hossam M; Kim, Seung-Jae; Zhou, Guofei; Fox, David A; Shahrara, Shiva

2018-05-01

IL-11 has been detected in inflamed joints; however, its role in the pathogenesis of arthritis is not yet clear. Studies were conducted to characterize the expression and functional significance of IL-11 and IL-11Rα in rheumatoid arthritis (RA). IL-11 levels were elevated in RA synovial fluid (SF) compared to osteoarthritis (OA) SF and plasma from RA, OA and normal individuals (NLs). Morphologic studies established that IL-11 was detected in lining fibroblasts and macrophages in addition to sublining endothelial cells and macrophages at higher levels in RA compared to NL synovial tissues. Since IL-11Rα was exclusively expressed in RA fibroblasts and endothelial cells, macrophages were not involved in IL-11 effector function. Ligation of IL-11 to IL-11Rα strongly provoked fibroblast infiltration into RA joint, while cell proliferation was unaffected by this process. Secretion of IL-8 and VEGF from IL-11 activated RA fibroblasts was responsible for the indirect effect of IL-11 on endothelial cell transmigration and tube formation. Moreover, IL-11 blockade impaired RA SF capacity to elicit endothelial cell transmigration and tube formation. We conclude that IL-11 binding to endothelial IL-11Rα can directly induce RA angiogenesis. In addition, secretion of proangiogenic factors from migrating fibroblasts potentiated by IL-11 can indirectly contribute to RA neovascularization.

Self-directed exploration provides a Ncs1-dependent learning bonus

PubMed Central

Mun, Ho-Suk; Saab, Bechara J.; Ng, Enoch; McGirr, Alexander; Lipina, Tatiana V.; Gondo, Yoichi; Georgiou, John; Roder, John C.

2015-01-01

Understanding the mechanisms of memory formation is fundamental to establishing optimal educational practices and restoring cognitive function in brain disease. Here, we show for the first time in a non-primate species, that spatial learning receives a special bonus from self-directed exploration. In contrast, when exploration is escape-oriented, or when the full repertoire of exploratory behaviors is reduced, no learning bonus occurs. These findings permitted the first molecular and cellular examinations into the coupling of exploration to learning. We found elevated expression of neuronal calcium sensor 1 (Ncs1) and dopamine type-2 receptors upon self-directed exploration, in concert with increased neuronal activity in the hippocampal dentate gyrus and area CA3, as well as the nucleus accumbens. We probed further into the learning bonus by developing a point mutant mouse (Ncs1P144S/P144S) harboring a destabilized NCS-1 protein, and found this line lacked the equivalent self-directed exploration learning bonus. Acute knock-down of Ncs1 in the hippocampus also decoupled exploration from efficient learning. These results are potentially relevant for augmenting learning and memory in health and disease, and provide the basis for further molecular and circuit analyses in this direction. PMID:26639399

Self-Directed and Incidental Learning. Symposium 26. [Concurrent Symposium Session at AHRD Annual Conference, 2000.

ERIC Educational Resources Information Center

2000

This packet contains three papers on self-directed and incidental learning from a symposium on human resource development (HRD). The first paper, "Self-Directed Learning for Supervisory Development" (Judy O'Neil, Maria Lamattina), reports on a study that looks at what research says needs to be in place to engage workers in self-directed learning…

Oncogenes induce the cancer-associated fibroblast phenotype

PubMed Central

Lisanti, Michael P; Martinez-Outschoorn, Ubaldo E; Sotgia, Federica

2013-01-01

Metabolic coupling, between mitochondria in cancer cells and catabolism in stromal fibroblasts, promotes tumor growth, recurrence, metastasis, and predicts anticancer drug resistance. Catabolic fibroblasts donate the necessary fuels (such as L-lactate, ketones, glutamine, other amino acids, and fatty acids) to anabolic cancer cells, to metabolize via their TCA cycle and oxidative phosphorylation (OXPHOS). This provides a simple mechanism by which metabolic energy and biomass are transferred from the host microenvironment to cancer cells. Recently, we showed that catabolic metabolism and “glycolytic reprogramming” in the tumor microenvironment are orchestrated by oncogene activation and inflammation, which originates in epithelial cancer cells. Oncogenes drive the onset of the cancer-associated fibroblast phenotype in adjacent normal fibroblasts via paracrine oxidative stress. This oncogene-induced transition to malignancy is “mirrored” by a loss of caveolin-1 (Cav-1) and an increase in MCT4 in adjacent stromal fibroblasts, functionally reflecting catabolic metabolism in the tumor microenvironment. Virtually identical findings were obtained using BRCA1-deficient breast and ovarian cancer cells. Thus, oncogene activation (RAS, NFkB, TGF-β) and/or tumor suppressor loss (BRCA1) have similar functional effects on adjacent stromal fibroblasts, initiating “metabolic symbiosis” and the cancer-associated fibroblast phenotype. New therapeutic strategies that metabolically uncouple oxidative cancer cells from their glycolytic stroma or modulate oxidative stress could be used to target this lethal subtype of cancers. Targeting “fibroblast addiction” in primary and metastatic tumor cells may expose a critical Achilles’ heel, leading to disease regression in both sporadic and familial cancers. PMID:23860382

Infection and cancer in multicellular organisms

PubMed Central

Ewald, Paul W.; Swain Ewald, Holly A.

2015-01-01

Evolutionary considerations suggest that oncogenic infections should be pervasive among animal species. Infection-associated cancers are well documented in humans and domestic animals, less commonly reported in undomesticated captive animals, and rarely documented in nature. In this paper, we review the literature associating infectious agents with cancer to evaluate the reasons for this pattern. Non-malignant infectious neoplasms occur pervasively in multicellular life, but oncogenic progression to malignancy is often uncertain. Evidence from humans and domestic animals shows that non-malignant infectious neoplasms can develop into cancer, although generally with low frequency. Malignant neoplasms could be difficult to find in nature because of a low frequency of oncogenic transformation, short survival after malignancy and reduced survival prior to malignancy. Moreover, the evaluation of malignancy can be ambiguous in nature, because criteria for malignancy may be difficult to apply consistently across species. The information available in the literature therefore does not allow for a definitive assessment of the pervasiveness of infectious cancers in nature, but the presence of infectious neoplasias and knowledge about the progression of benign neoplasias to cancer is consistent with a widespread but largely undetected occurrence. PMID:26056368

Altered physiological functions and ion currents in atrial fibroblasts from patients with chronic atrial fibrillation.

PubMed

Poulet, Claire; Künzel, Stephan; Büttner, Edgar; Lindner, Diana; Westermann, Dirk; Ravens, Ursula

2016-02-01

The contribution of human atrial fibroblasts to cardiac physiology and pathophysiology is poorly understood. Fibroblasts may contribute to arrhythmogenesis through fibrosis, or by directly altering electrical activity in cardiomyocytes. The objective of our study was to uncover phenotypic differences between cells from patients in sinus rhythm (SR) and chronic atrial fibrillation (AF), with special emphasis on electrophysiological properties. We isolated fibroblasts from human right atrial tissue for patch-clamp experiments, proliferation, migration, and differentiation assays, and gene expression profiling. In culture, proliferation and migration of AF fibroblasts were strongly impaired but differentiation into myofibroblasts was increased. This was associated with a higher number of AF fibroblasts expressing functional Nav1.5 channels. Strikingly Na(+) currents were considerably larger in AF cells. Blocking Na(+) channels in culture with tetrodotoxin did not affect proliferation, migration, or differentiation in neither SR nor AF cells. While freshly isolated fibroblasts showed mostly weak rectifier currents, fibroblasts in culture developed outward rectifier K(+) currents of similar amplitude between the SR and AF groups. Adding the K(+) channel blockers tetraethylammonium and 4-aminopyridin in culture reduced current amplitude and inhibited proliferation in the SR group only. Analysis of gene expression revealed significant differences between SR and AF in genes encoding for ion channels, collagen, growth factors, connexins, and cadherins. In conclusion, this study shows that under AF conditions atrial fibroblasts undergo phenotypic changes that are revealed in culture. Future experiments should be performed in situ to understand the nature of those changes and whether they affect cardiac electrical activity. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological

Toxoplasma gondii immunoglobulin G antibodies and nonfatal suicidal self-directed violence.

PubMed

Zhang, Yuanfen; Träskman-Bendz, Lil; Janelidze, Shorena; Langenberg, Patricia; Saleh, Ahmed; Constantine, Niel; Okusaga, Olaoluwa; Bay-Richter, Cecilie; Brundin, Lena; Postolache, Teodor T

2012-08-01

The primary aim was to relate Toxoplasma gondii seropositivity and serointensity to scores on the self-rated Suicide Assessment Scale (SUAS-S). Another aim was to reevaluate the previously reported positive association between T gondii serointensity and a history of nonfatal suicidal self-directed violence. This cross-sectional, observational study compared T gondii serointensity and seropositivity in plasma from 54 adult suicide attempters (inpatients at Lund University Hospital, Lund, Sweden) and 30 adult control subjects (randomly selected from the municipal population register in Lund, Sweden) recruited between 2006 and 2010. The potential of patients and controls for self-directed violence was evaluated with the SUAS-S. Psychiatric diagnoses were made according to DSM-IV criteria. Plasma samples were tested for immunoglobulin G antibodies to T gondii, cytomegalovirus, and herpes simplex virus type 1. Data were analyzed using multivariable logistic regression to investigate the association between T gondii serointensity or seropositivity and a history of nonfatal suicidal self-directed violence; multivariable linear regression was used to explore the relationship between T gondii serointensity or seropositivity and the SUAS-S. Both regression models included sex, age, and body mass index as covariates. Seropositivity of T gondii (adjusted odds ratio [OR] = 7.12; 95% CI, 1.66-30.6; P = .008) and serointensity of T gondii (adjusted OR = 2.01; 95% CI, 1.09-3.71; P = .03) were positively associated with a history of nonfatal suicidal self-directed violence. Seropositivity of T gondii was associated with higher SUAS-S scores, a relationship significant for the whole sample (P = .026), but not for suicide attempters only. No significant associations with other pathogens were identified. These results are consistent with previous reports on the association between T gondii infection and nonfatal suicidal self-directed violence. Confirming these results in future large

Less-structured time in children's daily lives predicts self-directed executive functioning.

PubMed

Barker, Jane E; Semenov, Andrei D; Michaelson, Laura; Provan, Lindsay S; Snyder, Hannah R; Munakata, Yuko

2014-01-01

Executive functions (EFs) in childhood predict important life outcomes. Thus, there is great interest in attempts to improve EFs early in life. Many interventions are led by trained adults, including structured training activities in the lab, and less-structured activities implemented in schools. Such programs have yielded gains in children's externally-driven executive functioning, where they are instructed on what goal-directed actions to carry out and when. However, it is less clear how children's experiences relate to their development of self-directed executive functioning, where they must determine on their own what goal-directed actions to carry out and when. We hypothesized that time spent in less-structured activities would give children opportunities to practice self-directed executive functioning, and lead to benefits. To investigate this possibility, we collected information from parents about their 6-7 year-old children's daily, annual, and typical schedules. We categorized children's activities as "structured" or "less-structured" based on categorization schemes from prior studies on child leisure time use. We assessed children's self-directed executive functioning using a well-established verbal fluency task, in which children generate members of a category and can decide on their own when to switch from one subcategory to another. The more time that children spent in less-structured activities, the better their self-directed executive functioning. The opposite was true of structured activities, which predicted poorer self-directed executive functioning. These relationships were robust (holding across increasingly strict classifications of structured and less-structured time) and specific (time use did not predict externally-driven executive functioning). We discuss implications, caveats, and ways in which potential interpretations can be distinguished in future work, to advance an understanding of this fundamental aspect of growing up.

Less-structured time in children's daily lives predicts self-directed executive functioning

PubMed Central

Barker, Jane E.; Semenov, Andrei D.; Michaelson, Laura; Provan, Lindsay S.; Snyder, Hannah R.; Munakata, Yuko

2014-01-01

Executive functions (EFs) in childhood predict important life outcomes. Thus, there is great interest in attempts to improve EFs early in life. Many interventions are led by trained adults, including structured training activities in the lab, and less-structured activities implemented in schools. Such programs have yielded gains in children's externally-driven executive functioning, where they are instructed on what goal-directed actions to carry out and when. However, it is less clear how children's experiences relate to their development of self-directed executive functioning, where they must determine on their own what goal-directed actions to carry out and when. We hypothesized that time spent in less-structured activities would give children opportunities to practice self-directed executive functioning, and lead to benefits. To investigate this possibility, we collected information from parents about their 6–7 year-old children's daily, annual, and typical schedules. We categorized children's activities as “structured” or “less-structured” based on categorization schemes from prior studies on child leisure time use. We assessed children's self-directed executive functioning using a well-established verbal fluency task, in which children generate members of a category and can decide on their own when to switch from one subcategory to another. The more time that children spent in less-structured activities, the better their self-directed executive functioning. The opposite was true of structured activities, which predicted poorer self-directed executive functioning. These relationships were robust (holding across increasingly strict classifications of structured and less-structured time) and specific (time use did not predict externally-driven executive functioning). We discuss implications, caveats, and ways in which potential interpretations can be distinguished in future work, to advance an understanding of this fundamental aspect of growing up

Multi-cellular natural killer (NK) cell clusters enhance NK cell activation through localizing IL-2 within the cluster

NASA Astrophysics Data System (ADS)

Kim, Miju; Kim, Tae-Jin; Kim, Hye Mi; Doh, Junsang; Lee, Kyung-Mi

2017-01-01

Multi-cellular cluster formation of natural killer (NK) cells occurs during in vivo priming and potentiates their activation to IL-2. However, the precise mechanism underlying this synergy within NK cell clusters remains unclear. We employed lymphocyte-laden microwell technologies to modulate contact-mediated multi-cellular interactions among activating NK cells and to quantitatively assess the molecular events occurring in multi-cellular clusters of NK cells. NK cells in social microwells, which allow cell-to-cell contact, exhibited significantly higher levels of IL-2 receptor (IL-2R) signaling compared with those in lonesome microwells, which prevent intercellular contact. Further, CD25, an IL-2R α chain, and lytic granules of NK cells in social microwells were polarized toward MTOC. Live cell imaging of lytic granules revealed their dynamic and prolonged polarization toward neighboring NK cells without degranulation. These results suggest that IL-2 bound on CD25 of one NK cells triggered IL-2 signaling of neighboring NK cells. These results were further corroborated by findings that CD25-KO NK cells exhibited lower proliferation than WT NK cells, and when mixed with WT NK cells, underwent significantly higher level of proliferation. These data highlights the existence of IL-2 trans-presentation between NK cells in the local microenvironment where the availability of IL-2 is limited.

Modes of Cell Death Induced by Photodynamic Therapy Using Zinc Phthalocyanine in Lung Cancer Cells Grown as a Monolayer and Three-Dimensional Multicellular Spheroids.

PubMed

Manoto, Sello L; Houreld, Nicolette; Hodgkinson, Natasha; Abrahamse, Heidi

2017-05-16

Photodynamic therapy (PDT) involves interaction of a photosensitizer, light, and molecular oxygen which produces singlet oxygen and subsequent tumour eradication. The development of second generation photosensitizers, such as phthalocyanines, has improved this technology. Customary monolayer cell culture techniques are, unfortunately, too simple to replicate treatment effects in vivo. Multicellular tumour spheroids may provide a better alternative since they mimic aspects of the human tumour environment. This study aimed to profile 84 genes involved in apoptosis following treatment with PDT on lung cancer cells (A549) grown in a monolayer versus three-dimensional multicellular tumour spheroids (250 and 500 μm). Gene expression profiling was performed 24 h post irradiation (680 nm; 5 J/cm²) with zinc sulfophthalocyanine (ZnPcS mix ) to determine the genes involved in apoptotic cell death. In the monolayer cells, eight pro-apoptotic genes were upregulated, and two were downregulated. In the multicellular tumour spheroids (250 µm) there was upregulation of only 1 gene while there was downregulation of 56 genes. Apoptosis in the monolayer cultured cells was induced via both the intrinsic and extrinsic apoptotic pathways. However, in the multicellular tumour spheroids (250 and 500 µm) the apoptotic pathway that was followed was not conclusive.

Peptide-directed self-assembly of functionalized polymeric nanoparticles. Part II: effects of nanoparticle composition on assembly behavior and multiple drug loading ability.

PubMed

Xiang, Xu; Ding, Xiaochu; Moser, Trevor; Gao, Qi; Shokuhfar, Tolou; Heiden, Patricia A

2015-04-01

Peptide-functionalized polymeric nanoparticles were designed and self-assembled into continuous nanoparticle fibers and three-dimensional scaffolds via ionic complementary peptide interaction. Different nanoparticle compositions can be designed to be appropriate for each desired drug, so that the release of each drug is individually controlled and the simultaneous sustainable release of multiple drugs is achieved in a single scaffold. A self-assembled scaffold membrane was incubated with NIH3T3 fibroblast cells in a culture dish that demonstrated non-toxicity and non-inhibition on cell proliferation. This type of nanoparticle scaffold combines the advantages of peptide self-assembly and the versatility of polymeric nanoparticle controlled release systems for tissue engineering. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alveolar type II cell-fibroblast interactions, synthesis and secretion of surfactant and type I collagen.

PubMed

Griffin, M; Bhandari, R; Hamilton, G; Chan, Y C; Powell, J T

1993-06-01

contained low levels of IGF-1 and the stimulation of type I collagen secretion was abolished when the conditioned medium was pre-incubated with antibodies to insulin-like growth factor 1 (IGF-1). There are important reciprocal interactions between alveolar type II cells and fibroblasts in co-culture. Direct contacts between alveolar type II cells and fibroblasts appear to have a trophic effect on cultured alveolar type II cells, increasing the levels of mRNA for SP-A. Rat lung alveolar type II cells appear to release a factor (possibly IGF-1) that stimulates type I collagen secretion by fibroblasts.

Direct Reprogramming of Mouse Fibroblasts into Functional Skeletal Muscle Progenitors.

PubMed

Bar-Nur, Ori; Gerli, Mattia F M; Di Stefano, Bruno; Almada, Albert E; Galvin, Amy; Coffey, Amy; Huebner, Aaron J; Feige, Peter; Verheul, Cassandra; Cheung, Priscilla; Payzin-Dogru, Duygu; Paisant, Sylvain; Anselmo, Anthony; Sadreyev, Ruslan I; Ott, Harald C; Tajbakhsh, Shahragim; Rudnicki, Michael A; Wagers, Amy J; Hochedlinger, Konrad

2018-05-08

Skeletal muscle harbors quiescent stem cells termed satellite cells and proliferative progenitors termed myoblasts, which play pivotal roles during muscle regeneration. However, current technology does not allow permanent capture of these cell populations in vitro. Here, we show that ectopic expression of the myogenic transcription factor MyoD, combined with exposure to small molecules, reprograms mouse fibroblasts into expandable induced myogenic progenitor cells (iMPCs). iMPCs express key skeletal muscle stem and progenitor cell markers including Pax7 and Myf5 and give rise to dystrophin-expressing myofibers upon transplantation in vivo. Notably, a subset of transplanted iMPCs maintain Pax7 expression and sustain serial regenerative responses. Similar to satellite cells, iMPCs originate from Pax7 + cells and require Pax7 itself for maintenance. Finally, we show that myogenic progenitor cell lines can be established from muscle tissue following small-molecule exposure alone. This study thus reports on a robust approach to derive expandable myogenic stem/progenitor-like cells from multiple cell types. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Transduction of Oct6 or Oct9 gene concomitant with Myc family gene induced osteoblast-like phenotypic conversion in normal human fibroblasts

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

Mizoshiri, N.; Department of Orthopaedics, Kyoto Prefectural University of Medicine, Kyoto; Kishida, T.

Introduction: Osteoblasts play essential roles in bone formation and regeneration, while they have low proliferation potential. Recently we established a procedure to directly convert human fibroblasts into osteoblasts (dOBs). Transduction of Runx2 (R), Osterix (X), Oct3/4 (O) and L-myc (L) genes followed by culturing under osteogenic conditions induced normal human fibroblasts to express osteoblast-specific genes and produce calcified bone matrix both in vitro and in vivo Intriguingly, a combination of only two factors, Oct3/4 and L-myc, significantly induced osteoblast-like phenotype in fibroblasts, but the mechanisms underlying the direct conversion remains to be unveiled. Materials and Methods: We examined which Oct family genesmore » and Myc family genes are capable of inducing osteoblast-like phenotypic conversion. Results: As result Oct3/4, Oct6 and Oct9, among other Oct family members, had the capability, while N-myc was the most effective Myc family gene. The Oct9 plus N-myc was the best combination to induce direct conversion of human fibroblasts into osteoblast-like cells. Discussion: The present findings may greatly contribute to the elucidation of the roles of the Oct and Myc proteins in osteoblast direct reprogramming. The results may also lead to establishment of novel regenerative therapy for various bone resorption diseases. - Highlights: • Introducing L-myc in a combination with either Oct3/4, Oct6 or Oct9 enables the conversion of fibroblasts to osteoblasts. • A combination of L-myc with Oct3/4 or Oct9 can induce the cells to a phenotype closer to normal osteoblasts. • N-myc was considered the most appropriate Myc family gene for induction of osteoblast-like phenotype in fibroblasts. • The combination of Oct9 plus N-myc has the strongest capability of inducing osteoblast-like phenotype.« less

A parallel implementation of an off-lattice individual-based model of multicellular populations

NASA Astrophysics Data System (ADS)

Harvey, Daniel G.; Fletcher, Alexander G.; Osborne, James M.; Pitt-Francis, Joe

2015-07-01

As computational models of multicellular populations include ever more detailed descriptions of biophysical and biochemical processes, the computational cost of simulating such models limits their ability to generate novel scientific hypotheses and testable predictions. While developments in microchip technology continue to increase the power of individual processors, parallel computing offers an immediate increase in available processing power. To make full use of parallel computing technology, it is necessary to develop specialised algorithms. To this end, we present a parallel algorithm for a class of off-lattice individual-based models of multicellular populations. The algorithm divides the spatial domain between computing processes and comprises communication routines that ensure the model is correctly simulated on multiple processors. The parallel algorithm is shown to accurately reproduce the results of a deterministic simulation performed using a pre-existing serial implementation. We test the scaling of computation time, memory use and load balancing as more processes are used to simulate a cell population of fixed size. We find approximate linear scaling of both speed-up and memory consumption on up to 32 processor cores. Dynamic load balancing is shown to provide speed-up for non-regular spatial distributions of cells in the case of a growing population.

Self-Directed Adult Learning: A Critical Paradigm Revisited.

ERIC Educational Resources Information Center

Caffarella, Rosemary S.; O'Donnell, Judith M.

1987-01-01

Seeks to analyze and categorize both data-based and conceptual articles on self-directed learning. Covers (1) verification studies, (2) nature of the method, (3) nature of the learner, (4) nature of the philosophical position, and (5) policy. Suggests future research topics. (Author/CH)

Relationship between Student's Self-Directed-Learning Readiness and Academic Self-Efficacy and Achievement Motivation in Students

ERIC Educational Resources Information Center

Saeid, Nasim; Eslaminejad, Tahere

2017-01-01

Self-directed learning readiness to expand and enhance learning, This is an important goal of higher education, Besides his academic self-efficacy can be improved efficiency and Achievement Motivation, so understanding how to use these strategies by students is very important. Because the purpose this study is determination of relationship between…

A Quasi-Linear Behavioral Model and an Application to Self-Directed Learning

NASA Technical Reports Server (NTRS)

Ponton, Michael K.; Carr, Paul B.

1999-01-01

A model is presented that describes the relationship between one's knowledge of the world and the concomitant personal behaviors that serve as a mechanism to obtain desired outcomes. Integrated within this model are the differing roles that outcomes serve as motivators and as modifiers to one's worldview. The model is dichotomized between general and contextual applications. Because learner self-directedness (a personal characteristic) involves cognition and affection while self-directed learning (a pedagogic process) encompasses conation, behavior and introspection, the model can be dichotomized again in another direction. Presented also are the roles that cognitive motivation theories play in moving an individual through this behavioral model and the roles of wishes, self-efficacy, opportunity and self-influence.

Mitomycin C induces fibroblasts apoptosis and reduces epidural fibrosis by regulating miR-200b and its targeting of RhoE.

PubMed

Sun, Yu; Ge, Yingbin; Fu, Yuxuan; Yan, Lianqi; Cai, Jun; Shi, Kun; Cao, Xiaojian; Lu, Chun

2015-10-15

Mitomycin C (MMC) is known to reduce epidural fibrosis, but the underlying mechanisms have not yet been elucidated. Aberrant miR-200b expressions have been reported in multiple types of fibrotic tissues from many diseases. The aim of this study was to clarify the mechanism by which MMC induces fibroblasts apoptosis and reduces epidural fibrosis. The expression of miR-200b in human fibroblasts was determined after MMC treatment, and the targeted association between miR-200b and RhoE was determined using the luciferase activity assay. The effects of MMC and miR-200b on human fibroblasts apoptosis were evaluated using flow cytometry and western blot analysis. The effects of MMC and miR-200b on epidural fibrosis were evaluated using the Rydell classification, hydroxyproline content, apoptotic cell count and histological analysis. The study revealed that MMC could significantly downregulate miR-200b expression and induce human fibroblasts apoptosis. The direct downregulation of miR-200b could induce human fibroblasts apoptosis. Furthermore, we identified the binding sequence for miR-200b within the 3' untranslated region of RhoE. RhoE was confirmed to be a direct target of miR-200b, and RhoE itself acted as a promoter of fibroblasts apoptosis. The inhibition of miR-200b increased fibroblasts apoptosis and reduced epidural fibrosis in rats, which was in accordance with the effect of MMC. This study suggests that MMC induces fibroblasts apoptosis and reduces epidural fibrosis by regulating miR-200b expression and its targeting of RhoE. Copyright © 2015 Elsevier B.V. All rights reserved.

A density gradient of VAPG peptides on a cell-resisting surface achieves selective adhesion and directional migration of smooth muscle cells over fibroblasts.

PubMed

Yu, Shan; Zuo, Xingang; Shen, Tao; Duan, Yiyuan; Mao, Zhengwei; Gao, Changyou

2018-05-01

Selective adhesion and migration of smooth muscle cells (SMCs) over fibroblasts (FIBs) is required to prevent adventitia fibrosis in vascular regeneration. In this study, a uniform cell-resisting layer of poly(ethylene glycol) (PEG) with a density gradient of azide groups was generated on a substrate by immobilizing two kinds of PEG molecules in a gradient manner. A density gradient of alkynyl-functionalized Val-Ala-Pro-Gly (VAPG) peptides was then prepared on the PEG layer via click chemistry. The VAPG density gradient was characterized by fluorescence imaging, revealing the gradual enhancement of the fluorescent intensity along the substrate direction. The adhesion and mobility of SMCs were selectively enhanced on the VAPG density gradient, leading to directional migration toward the higher peptide density (up to 84%). In contrast, the adhesion and mobility of FIBs were significantly weakened. The net displacement of SMCs also significantly increased compared with that on tissue culture polystyrene (TCPS) and that of FIBs on the gradient. The mitogen-activated protein kinase (MAPK) signaling pathways related to cell migration were studied, showing higher expressions of functional proteins from SMCs on the VAPG-modified surface in a density-dependent manner. For the first time the selective adhesion and directional migration of SMCs over FIBs was achieved by an elaborative design of a gradient surface, leading to a new insight in design of novel vascular regenerative materials. Selective cell adhesion and migration guided by regenerative biomaterials are extremely important for the regeneration of targeted tissues, which can avoid the drawbacks of incorrect and uncontrolled responses of tissue cells to implants. For example, selectivity of smooth muscle cells (SMCs) over fibroblasts (FIBs) is required to prevent adventitia fibrosis in vascular regeneration. Herein we prepare a uniform cell-repelling layer, on which SMCs-selective Val-Ala-Pro-Gly (VAPG) peptides

Decimetre-scale multicellular eukaryotes from the 1.56-billion-year-old Gaoyuzhuang Formation in North China

PubMed Central

Zhu, Shixing; Zhu, Maoyan; Knoll, Andrew H.; Yin, Zongjun; Zhao, Fangchen; Sun, Shufen; Qu, Yuangao; Shi, Min; Liu, Huan

2016-01-01

Fossils of macroscopic eukaryotes are rarely older than the Ediacaran Period (635–541 million years (Myr)), and their interpretation remains controversial. Here, we report the discovery of macroscopic fossils from the 1,560-Myr-old Gaoyuzhuang Formation, Yanshan area, North China, that exhibit both large size and regular morphology. Preserved as carbonaceous compressions, the Gaoyuzhuang fossils have statistically regular linear to lanceolate shapes up to 30 cm long and nearly 8 cm wide, suggesting that the Gaoyuzhuang fossils record benthic multicellular eukaryotes of unprecedentedly large size. Syngenetic fragments showing closely packed ∼10 μm cells arranged in a thick sheet further reinforce the interpretation. Comparisons with living thalloid organisms suggest that these organisms were photosynthetic, although their phylogenetic placement within the Eukarya remains uncertain. The new fossils provide the strongest evidence yet that multicellular eukaryotes with decimetric dimensions and a regular developmental program populated the marine biosphere at least a billion years before the Cambrian Explosion. PMID:27186667

The Readiness of Adults with Attention Deficit Hyperactivity Disorder for Self-Directed Learning

ERIC Educational Resources Information Center

Wright, Melissa Sue

2011-01-01

This study investigated the readiness for self-directed learning of adults with Attention Deficit Hyperactivity Disorder (ADHD), as well as their overall educational experiences. Using Guglielmino's Self-Directed Learning Readiness Scale for Adults (SDLRS-A), the researcher investigated whether the following factors were significantly related to…

Mimosa Origami: A nanostructure-enabled directional self-organization regime of materials

PubMed Central

Wong, William S. Y.; Li, Minfei; Nisbet, David R.; Craig, Vincent S. J.; Wang, Zuankai; Tricoli, Antonio

2016-01-01

One of the innate fundamentals of living systems is their ability to respond toward distinct stimuli by various self-organization behaviors. Despite extensive progress, the engineering of spontaneous motion in man-made inorganic materials still lacks the directionality and scale observed in nature. We report the directional self-organization of soft materials into three-dimensional geometries by the rapid propagation of a folding stimulus along a predetermined path. We engineer a unique Janus bilayer architecture with superior chemical and mechanical properties that enables the efficient transformation of surface energy into directional kinetic and elastic energies. This Janus bilayer can respond to pinpoint water stimuli by a rapid, several-centimeters-long self-assembly that is reminiscent of the Mimosa pudica’s leaflet folding. The Janus bilayers also shuttle water at flow rates up to two orders of magnitude higher than traditional wicking-based devices, reaching velocities of 8 cm/s and flow rates of 4.7 μl/s. This self-organization regime enables the ease of fabricating curved, bent, and split flexible channels with lengths greater than 10 cm, demonstrating immense potential for microfluidics, biosensors, and water purification applications. PMID:28861471

Mimosa Origami: A nanostructure-enabled directional self-organization regime of materials.

PubMed

Wong, William S Y; Li, Minfei; Nisbet, David R; Craig, Vincent S J; Wang, Zuankai; Tricoli, Antonio

2016-06-01

One of the innate fundamentals of living systems is their ability to respond toward distinct stimuli by various self-organization behaviors. Despite extensive progress, the engineering of spontaneous motion in man-made inorganic materials still lacks the directionality and scale observed in nature. We report the directional self-organization of soft materials into three-dimensional geometries by the rapid propagation of a folding stimulus along a predetermined path. We engineer a unique Janus bilayer architecture with superior chemical and mechanical properties that enables the efficient transformation of surface energy into directional kinetic and elastic energies. This Janus bilayer can respond to pinpoint water stimuli by a rapid, several-centimeters-long self-assembly that is reminiscent of the Mimosa pudica 's leaflet folding. The Janus bilayers also shuttle water at flow rates up to two orders of magnitude higher than traditional wicking-based devices, reaching velocities of 8 cm/s and flow rates of 4.7 μl/s. This self-organization regime enables the ease of fabricating curved, bent, and split flexible channels with lengths greater than 10 cm, demonstrating immense potential for microfluidics, biosensors, and water purification applications.

Dissolved Gases and Ice Fracturing During the Freezing of a Multicellular Organism: Lessons from Tardigrades

PubMed Central

Kletetschka, Gunther; Hruba, Jolana

2015-01-01

Abstract Three issues are critical for successful cryopreservation of multicellular material: gases dissolved in liquid, thermal conductivity of the tissue, and localization of microstructures. Here we show that heat distribution is controlled by the gas amount dissolved in liquids and that when changing the liquid into solid, the dissolved gases either form bubbles due to the absence of space in the lattice of solids and/or are migrated toward the concentrated salt and sugar solution at the cost of amount of heat required to be removed to complete a solid-state transition. These factors affect the heat distribution in the organs to be cryopreserved. We show that the gas concentration issue controls fracturing of ice when freezing. There are volumetric changes not only when changing the liquid into solid (volume increases) but also reduction of the volume when reaching lower temperatures (volume decreases). We discuss these issues parallel with observations of the cryosurvivability of multicellular organisms, tardigrades, and discuss their analogy for cryopreservation of large organs. PMID:26309797

Evaluation of group and self-directed formats of the Arthritis Foundation's Walk With Ease Program.

PubMed

Callahan, Leigh F; Shreffler, Jack H; Altpeter, Mary; Schoster, Britta; Hootman, Jennifer; Houenou, Laura O; Martin, Kathryn R; Schwartz, Todd A

2011-08-01

To evaluate the effects of a revised 6-week walking program for adults with arthritis, Walk With Ease (WWE), delivered in 2 formats, instructor-led group or self-directed. In an observational pre-post study design, 462 individuals with self-reported arthritis selected either a group format (n = 192) or a self-directed (n = 270) format. Performance and self-reported outcomes were assessed at baseline and at 6 weeks. Self-reported outcomes were assessed at 1 year. Adjusted mean outcome values for group and self-directed participants were determined using regression models, adjusting for covariates. At 6 weeks, significant adjusted mean improvements (P < 0.05) were seen for nearly all self-report and performance measures in both formats. Modest to moderate effect sizes (ES) were seen for disability (ES 0.16-0.23), pain, fatigue, and stiffness (ES 0.21-0.40), and helplessness (ES 0.24-0.28). The Arthritis Self-Efficacy (ASE) pain and symptom scales had modest improvements (ES 0.09-0.21). The performance measures of strength (ES 0.29-0.35), balance (ES 0.12-0.36), and walking pace (ES 0.12-0.32) all showed modest to moderate improvements. No adverse events were reported for either format. At 1 year, both formats showed modest improvement in ASE pain, but there were 5 outcomes where self-directed participants showed significant improvement, while the group participants did not. The revised WWE program decreases disability and improves arthritis symptoms, self-efficacy, and perceived control, balance, strength, and walking pace in individuals with arthritis, regardless of whether they are taking a group class or doing the program as self-directed walkers. At 1 year, some benefits are maintained, particularly among the self-directed. This is a safe, easy, and inexpensive program to promote community-based physical activity. Copyright © 2011 by the American College of Rheumatology.

Directed evolution of polymerase function by compartmentalized self-replication.

PubMed

Ghadessy, F J; Ong, J L; Holliger, P

2001-04-10

We describe compartmentalized self-replication (CSR), a strategy for the directed evolution of enzymes, especially polymerases. CSR is based on a simple feedback loop consisting of a polymerase that replicates only its own encoding gene. Compartmentalization serves to isolate individual self-replication reactions from each other. In such a system, adaptive gains directly (and proportionally) translate into genetic amplification of the encoding gene. CSR has applications in the evolution of polymerases with novel and useful properties. By using three cycles of CSR, we obtained variants of Taq DNA polymerase with 11-fold higher thermostability than the wild-type enzyme or with a >130-fold increased resistance to the potent inhibitor heparin. Insertion of an extra stage into the CSR cycle before the polymerase reaction allows its application to enzymes other than polymerases. We show that nucleoside diphosphate kinase and Taq polymerase can form such a cooperative CSR cycle based on reciprocal catalysis, whereby nucleoside diphosphate kinase produces the substrates required for the replication of its own gene. We also find that in CSR the polymerase genes themselves evolve toward more efficient replication. Thus, polymerase genes and their encoded polypeptides cooperate to maximize postselection copy number. CSR should prove useful for the directed evolution of enzymes, particularly DNA or RNA polymerases, as well as for the design and study of in vitro self-replicating systems mimicking prebiotic evolution and viral replication.

Influence of Adult Goal-Setting Instruction on Students' Responsibility toward Self-Directed Competencies

ERIC Educational Resources Information Center

Apa Browne, Lynn Geri

2014-01-01

Elementary grade students in a mid-Atlantic state school district have not been meeting academic standards on state assessments. Research indicates that academic achievement is connected to self-directed readiness to learn; however, often the instruction in strategies for student self-directed readiness to learn remains teacher-centered. The…

Variations in Consumer Self-Determination within US Psychiatric Advance Directives

ERIC Educational Resources Information Center

Zeman, Laura Dreuth; Swanke, Jayme

2008-01-01

Advance directives are legal documents that formalize consumer psychiatric care preferences. This article examines the statutes and goals of US psychiatric advance directives within the framework of consumer self-determination, a priority in national mental health reform. It seeks to distinguish between state models based on the degree that…

Esophageal Squamous Cell Carcinoma Cells Modulate Chemokine Expression and Hyaluronan Synthesis in Fibroblasts.

PubMed

Kretschmer, Inga; Freudenberger, Till; Twarock, Sören; Yamaguchi, Yu; Grandoch, Maria; Fischer, Jens W

2016-02-19

The aim of this study was to characterize the interaction of KYSE-410, an esophageal squamous cell carcinoma cell line, and fibroblasts with respect to the extracellular matrix component hyaluronan (HA) and chemokine expression. KYSE-410 cells induced the mRNA expression of HA synthase 2 (Has2) in normal skin fibroblasts (SF) only in direct co-cultures. Parallel to Has2 mRNA, Has2 antisense RNA (Has2os2) was up-regulated in co-cultures. Knockdown of LEF1, a downstream target of Wnt signaling, abrogated Has2 and Has2os2 induction. After knockdown of Has2 in SF, significantly less α-smooth muscle actin expression was detected in co-cultures. Moreover, it was investigated whether the phenotype of KYSE-410 was affected in co-culture with SF and whether Has2 knockdown in SF had an impact on KYSE-410 cells in co-culture. However, no effects on epithelial-mesenchymal transition markers, proliferation, and migration were detected. In addition to Has2 mRNA, the chemokine CCL5 was up-regulated and CCL11 was down-regulated in SF in co-culture. Furthermore, co-cultures of KYSE-410 cells and cancer-associated fibroblasts (CAF) were investigated. Similar to SF, Has2 and Ccl5 were up-regulated and Ccl11 was down-regulated in CAF in co-culture. Importantly and in contrast to SF, inhibiting HA synthesis by 4-methylumbelliferone abrogated the effect of co-culture on Ccl5 in CAF. Moreover, HA was found to promote adhesion of CD4(+) but not CD8(+) cells to xenogaft tumor tissues. In conclusion, direct co-culture of esophageal squamous cell carcinoma and fibroblasts induced stromal HA synthesis via Wnt/LEF1 and altered the chemokine profile of stromal fibroblasts, which in turn may affect the tumor immune response. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Making Choices: Self-Directed Teams or Total Quality Management?

ERIC Educational Resources Information Center

Holpp, Lawrence

1992-01-01

Describes differences between total quality management and self-directed teams in terms of job design, decision making, flexibility, supervision, labor relations, quality, customers, and training. Offers suggestions for which method to choose when. (SK)

Scalable Directed Self-Assembly Using Ultrasound Waves

DTIC Science & Technology

2015-09-04

SECURITY CLASSIFICATION OF: We aim to understand how ultrasound waves can be used to create organized patterns of nanoparticles in a host medium such...as a polymer matrix material. The critical difference between the ultrasound technology studied in this project, and other directed self-assembly...of nanoparticles dispersed in a host medium are assembled by means of standing ultrasound waves. Additionally, we have obtained experimental

3D multicellular model of shock wave-cell interaction.

PubMed

Li, Dongli; Hallack, Andre; Cleveland, Robin O; Jérusalem, Antoine

2018-05-01

Understanding the interaction between shock waves and tissue is critical for ad- vancing the use of shock waves for medical applications, such as cancer therapy. This work aims to study shock wave-cell interaction in a more realistic environment, relevant to in vitro and in vivo studies, by using 3D computational models of healthy and cancerous cells. The results indicate that for a single cell embedded in an extracellular environment, the cellular geometry does not influence significantly the membrane strain but does influence the von Mises stress. On the contrary, the presence of neighbouring cells has a strong effect on the cell response, by increasing fourfold both quantities. The membrane strain response of a cell converges with more than three neighbouring cell layers, indicating that a cluster of four layers of cells is sufficient to model the membrane strain in a large domain of tissue. However, a full 3D tissue model is needed if the stress evaluation is of main interest. A tumour mimicking multicellular spheroid model is also proposed to study mutual interaction between healthy and cancer cells and shows that cancer cells can be specifically targeted in an early stage tumour-mimicking environment. This work presents 3D computational models of shock-wave/cell interaction in a biophysically realistic environment using real cell morphology in tissue-mimicking phantom and multicellular spheroid. Results show that cell morphology does not strongly influence the membrane strain but influences the von Mises stress. While the presence of neighbouring cells significantly increases the cell response, four cell layers are enough to capture the membrane strain change in tissue. However, a full tissue model is necessary if accurate stress analysis is needed. The work also shows that cancer cells can be specifically targetted in early stage tumourmimicking environment. This work is a step towards realistic modelling of shock-wave/cell interactions in tissues and

Achievement of exercise objectives and satisfaction with the walk with ease program-group and self-directed participants.

PubMed

Nyrop, Kirsten A; Cleveland, Rebecca; Callahan, Leigh F

2014-01-01

This study presents group (instructor-led) and self-directed (nongroup) participant achievement of exercise objectives and satisfaction with the Arthritis Foundation's Walk With Ease (WWE) program at 6 weeks postintervention and 1-year follow-up. Secondary data analysis. Rural and urban counties in North Carolina. Four hundred sixty-two adults with self-reported joint pain/stiffness or physician-diagnosed arthritis, age ≥18 years, no serious medical condition, no cognitive impairments, English speaking. Intervention. WWE is a 6-week community-based walking program offered in two formats-group and self-directed. Self-report measures collected at baseline, 6 weeks, and 1 year. Descriptive statistics, χ (2) and t-tests. Individuals self-selected either group (n = 192) or self-directed (n = 270) format. On average, participants were age 67, Caucasian (70%), and female (88%). Mean minutes per walk increased from 16.7 at baseline to 34.2 minutes at 1 year among group participants, and from 16.5 to 33.7 minutes among self-directed. At 1 year, 59.6% of group and 69.3% of self-directed participants reported continued walking (p = .06). Group participants were more likely than self-directed to do recommended stretching (p < .02) and warm-up/cool-down exercises (p < .01). Group and self-directed participants have similar self-reported walking outcomes but have some differences in their utilization of WWE recommendations.

[Study on three kinds of gasoline oxygenates-induced DNA damage in mice fibroblasts].

PubMed

Song, Chonglin; Zhang, Zhifu; Chen, Xue; Zhang, Yanfeng; Wang, Chunhua; Liu, Keming

2002-10-01

To study DNA damage of three kinds of gasoline oxygenates. Single cell gel electrophoresis assay(Comet assay) was used to detect the damage effects of three gasoline oxygenates[methyl tertiary butyl ether(MTBE), ethanol anhydrous(EA) and dimethyl carbonate(DMC)] on DNA in L-929 mice fibroblasts. In certain concentation(37.500-150.000 mg/ml), MTBE could directly cause DNA damage of L-929 mice fibroblasts. There was obvious dose-effect relationship, i.e. when the concentration of MTBE was increased from 9.375 to 150.000 mg/ml, the comet rate also increased from 4% to 85%, and the length of comet tail changed correspondingly. The results of EA and DMC were negative. Under the condition of this experiment(150.000 mg/ml), MTBE could directly cause DNA damage while the effect of EA and DMC on DNA damage was not found.

Self-directed learning readiness of Asian students: students perspective on a hybrid problem based learning curriculum.

PubMed

Leatemia, Lukas D; Susilo, Astrid P; van Berkel, Henk

2016-12-03

To identify the student's readiness to perform self-directed learning and the underlying factors influencing it on the hybrid problem based learning curriculum. A combination of quantitative and qualitative studies was conducted in five medical schools in Indonesia. In the quantitative study, the Self Directed Learning Readiness Scale was distributed to all students in all batches, who had experience with the hybrid problem based curriculum. They were categorized into low- and high -level based on the score of the questionnaire. Three focus group discussions (low-, high-, and mixed level) were conducted in the qualitative study with six to twelve students chosen randomly from each group to find the factors influencing their self-directed learning readiness. Two researchers analysed the qualitative data as a measure of triangulation. The quantitative study showed only half of the students had a high-level of self-directed learning readiness, and a similar trend also occurred in each batch. The proportion of students with a high level of self-directed learning readiness was lower in the senior students compared to more junior students. The qualitative study showed that problem based learning processes, assessments, learning environment, students' life styles, students' perceptions of the topics, and mood, were factors influencing their self-directed learning. A hybrid problem based curriculum may not fully affect the students' self-directed learning. The curriculum system, teacher's experiences, student's background and cultural factors might contribute to the difficulties for the student's in conducting self-directed learning.

Conditions Enhancing Self-Directed Learning in the Workplace. A Report to the Participants.

ERIC Educational Resources Information Center

1992

The appreciative inquiry process was used to identify conditions enhancing self-directed learning. Participants in the project did the following: (1) used the five-step process to identify factors/conditions/forces that seemed to cause self-directed learning to occur; (2) created a matrix by combining the factors/conditions/forces with six…

Directional self-cleaning superoleophobic surface.

PubMed

Zhao, Hong; Law, Kock-Yee

2012-08-14

In this work, we report the creation of a grooved surface comprising 3 μm grooves (height ~4 μm) separated by 3 μm from each other on a silicon wafer by photolithography. The grooved surface was then modified chemically with a fluorosilane layer (FOTS). The surface property was studied by both static and dynamic contact angle measurements using water, hexadecane, and a polyethylene wax ink as the probing liquids. Results show that the grooved surface is both superhydrophobic and superoleophobic. Its observed contact angles agree well with the calculated Cassie-Baxter angles. More importantly, we are able to make a replica of the composite wax ink-air interface and study it by SEM. Microscopy results not only show that the droplet of the wax ink "sits" on air in the composite interface but also further reveal that the ink drop actually pins underneath the re-entrant structure in the side wall of the grooved structure. Contact angle measurement results indicate that wetting on the grooved surface is anisotropic. Although liquid drops are found to have lower static and advancing contact angles in the parallel direction, the drops are found to be more mobile, showing smaller hysteresis and lower sliding angles (as compared to the FOTS wafer surface and a comparable 3-μm-diameter pillar array FOTS surface). The enhanced mobility is attributable to the lowering of the resistance against an advancing liquid because 50% of the advancing area is made of a solid strip where the liquid likes to wet. This also implies that the contact line for advancing is no longer smooth but rather is ragged, having the solid strip area leading the wetting and the air strip area trailing behind. This interpretation is supported by imaging the geometry of the contact lines using molten ink drops recovered from the sliding angle experiments in both the parallel and orthogonal directions. Because the grooved surface is mechanically stronger against mechanical abrasion, the self

Self-organized, near-critical behavior during aggregation in Dictyostelium discoideum

NASA Astrophysics Data System (ADS)

de Palo, Giovanna; Yi, Darvin; Gregor, Thomas; Endres, Robert

During starvation, the social amoeba Dictyostelium discoideum aggregates artfully via pattern formation into a multicellular slug and finally spores. The aggregation process is mediated by the secretion and sensing of cyclic adenosine monophosphate, leading to the synchronized movement of cells. The whole process is a remarkable example of collective behavior, spontaneously emerging from single-cell chemotaxis. Despite this phenomenon being broadly studied, a precise characterization of the transition from single cells to multicellularity has been elusive. Here, using fluorescence imaging data of thousands of cells, we investigate the role of cell shape in aggregation, demonstrating remarkable transitions in cell behavior. To better understand their functional role, we analyze cell-cell correlations and provide evidence for self-organization at the onset of aggregation (as opposed to leader cells), with features of criticality in this finite system. To capture the mechanism of self-organization, we extend a detailed single-cell model of D.discoideum chemotaxis by adding cell-cell communication. We then use these results to extract a minimal set of rules leading to aggregation in the population model. If universal, similar rules may explain other types of collective cell behavior.

Exosome-mediated delivery of miR-9 induces cancer-associated fibroblast-like properties in human breast fibroblasts

PubMed Central

Baroni, S; Romero-Cordoba, S; Plantamura, I; Dugo, M; D'Ippolito, E; Cataldo, A; Cosentino, G; Angeloni, V; Rossini, A; Daidone, M G; Iorio, M V

2016-01-01

It is established that the interaction between microenvironment and cancer cells has a critical role in tumor development, given the dependence of neoplastic cells on stromal support. However, how this communication promotes the activation of normal (NFs) into cancer-associated fibroblasts (CAFs) is still not well understood. Most microRNA (miRNA) studies focused on tumor cell, but there is increasing evidence of their involvement in reprogramming NFs into CAFs. Here we show that miR-9, upregulated in various breast cancer cell lines and identified as pro-metastatic miRNA, affects the properties of human breast fibroblasts, enhancing the switch to CAF phenotype, thus contributing to tumor growth. Expressed at higher levels in primary triple-negative breast CAFs versus NFs isolated from patients, miR-9 improves indeed migration and invasion capabilities when transfected in immortalized NFs; viceversa, these properties are strongly impaired in CAFs upon miR-9 inhibition. We also demonstrate that tumor-secreted miR-9 can be transferred via exosomes to recipient NFs and this uptake results in enhanced cell motility. Moreover, we observed that this miRNA is also secreted by fibroblasts and in turn able to alter tumor cell behavior, by modulating its direct target E-cadherin, and NFs themselves. Consistently with the biological effects observed, gene expression profiles of NFs upon transient transfection with miR-9 show the modulation of genes mainly involved in cell motility and extracellular matrix remodeling pathways. Finally, we were able to confirm the capability of NFs transiently transfected with miR-9 to promote in vivo tumor growth. Taken together, these data provide new insights into the role of miR-9 as an important player in the cross-talk between cancer cells and stroma. PMID:27468688

Exosome-mediated delivery of miR-9 induces cancer-associated fibroblast-like properties in human breast fibroblasts.

PubMed

Baroni, S; Romero-Cordoba, S; Plantamura, I; Dugo, M; D'Ippolito, E; Cataldo, A; Cosentino, G; Angeloni, V; Rossini, A; Daidone, M G; Iorio, M V

2016-07-28

It is established that the interaction between microenvironment and cancer cells has a critical role in tumor development, given the dependence of neoplastic cells on stromal support. However, how this communication promotes the activation of normal (NFs) into cancer-associated fibroblasts (CAFs) is still not well understood. Most microRNA (miRNA) studies focused on tumor cell, but there is increasing evidence of their involvement in reprogramming NFs into CAFs. Here we show that miR-9, upregulated in various breast cancer cell lines and identified as pro-metastatic miRNA, affects the properties of human breast fibroblasts, enhancing the switch to CAF phenotype, thus contributing to tumor growth. Expressed at higher levels in primary triple-negative breast CAFs versus NFs isolated from patients, miR-9 improves indeed migration and invasion capabilities when transfected in immortalized NFs; viceversa, these properties are strongly impaired in CAFs upon miR-9 inhibition. We also demonstrate that tumor-secreted miR-9 can be transferred via exosomes to recipient NFs and this uptake results in enhanced cell motility. Moreover, we observed that this miRNA is also secreted by fibroblasts and in turn able to alter tumor cell behavior, by modulating its direct target E-cadherin, and NFs themselves. Consistently with the biological effects observed, gene expression profiles of NFs upon transient transfection with miR-9 show the modulation of genes mainly involved in cell motility and extracellular matrix remodeling pathways. Finally, we were able to confirm the capability of NFs transiently transfected with miR-9 to promote in vivo tumor growth. Taken together, these data provide new insights into the role of miR-9 as an important player in the cross-talk between cancer cells and stroma.

Self-Directed Learning: A Tool for Lifelong Learning

ERIC Educational Resources Information Center

Boyer, Stefanie L.; Edmondson, Diane R.; Artis, Andrew B.; Fleming, David

2014-01-01

A meta-analytic review of self-directed learning (SDL) research over 30 years, five countries, and across multiple academic disciplines is used to explore its relationships with five key nomologically related constructs for effective workplace learning. The meta-analysis revealed positive relationships between SDL and internal locus of control,…

Promoting Self-Directed Revision in EFL Writing Classes

ERIC Educational Resources Information Center

Coomber, Matthew

2016-01-01

Second language writers need to develop the ability to revise their writing independently of third party advice; thus, it is important that teachers devise methods by which to promote habits of self-directed revision. This quasi-experimental study investigates three classroom activities designed to encourage students to independently revise essays…

Anti-Aging Effects of the Hanwoo Leg Bone, Foot and Tail Infusions (HLI, HFI and HTI) on Skin Fibroblast.

PubMed

Seol, Ja Young; Yoon, Ji Young; Jeong, Hee Sun; Joo, Nami; Choi, Soon Young

2016-01-01

Many researchers revealed that collagen contribute to maintaining the skin's elasticity and inhibit wrinkling of skin. Korean native cattle (Hanwoo) bone (leg bone, foot and tail) infusion contains the various inorganic materials, collagen and chondroitin sulfate. All of this, a large quantity of collagen is included in Hanwoo infusion. Therefore, this study emphasized on the effects of collagen in the Hanwoo bone infusion. For the first time, Hanwoo bone infusions were directly added to the media of Human Dermal Fibroblast (NHDF-c) to test anti-aging effects. First, it was identified that growth rate of skin fibroblast was increased. Furthermore, the Hanwoo bone infusion increased a 50% of fibroblast collagen synthesis. Also, suppression of skin fibroblast aging was confirmed by treatment Hanwoo bone infusion. In conclusion, this study demonstrates the effects of infusion made from Hanwoo leg bone, foot and tail on anti-aging, wrinkle inhibiting and skin fibroblast elasticity maintaining. Therefore, this study identified that traditional infusion has effects that are good for skin elasticity.

Chinese baccalaureate nursing students' readiness for self-directed learning.

PubMed

Yuan, Hao Bin; Williams, Beverly A; Fang, Jin Bo; Pang, Dong

2012-05-01

This descriptive cross-sectional study was conducted with 536 Chinese nursing students to explore students' readiness for self-directed learning (SDL). The Self-Directed Learning Readiness (SDLR) Scale for nursing education (Chinese translation version) was used. The value of the content validity index tested by five experts was 0.915. A measure of internal consistency (Cronbach's alpha) was 0.925 on the total scale. Students possessed readiness for SDL with a mean score of 157.72 (S.D.=15.08, 62.3% in high level, and 37.7% in low level). The attributes of Chinese students, such as a strong sense of responsibility and perseverance, due diligence and rigorous self-discipline, enable students to take the initiative and responsibility for their own learning. The existing variation in students' readiness for SDL is helpful in identifying student characteristics that might be used to modify learning activities for these students. Senior students had higher scores for SDLR than junior students. This finding likely reflects the maturational process of developing self-directedness. Promoting SDL skills is a challenging process for faculty members and students. It is helpful if nurse educators assess the learning styles and preferences of their students in order to determine the level of SDL activities to include from year to year in the curriculum. Copyright © 2011 Elsevier Ltd. All rights reserved.

Hypoxia induces pulmonary fibroblast proliferation through NFAT signaling.

PubMed

Senavirathna, Lakmini Kumari; Huang, Chaoqun; Yang, Xiaoyun; Munteanu, Maria Cristina; Sathiaseelan, Roshini; Xu, Dao; Henke, Craig A; Liu, Lin

2018-02-09

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and typically fatal lung disease with a very low survival rate. Excess accumulation of fibroblasts, myofibroblasts and extracellular matrix creates hypoxic conditions within the lungs, causing asphyxiation. Hypoxia is, therefore, one of the prominent features of IPF. However, there have been few studies concerning the effects of hypoxia on pulmonary fibroblasts. In this study, we investigated the molecular mechanisms of hypoxia-induced lung fibroblast proliferation. Hypoxia increased the proliferation of normal human pulmonary fibroblasts and IPF fibroblasts after exposure for 3-6 days. Cell cycle analysis demonstrated that hypoxia promoted the G1/S phase transition. Hypoxia downregulated cyclin D1 and A2 levels, while it upregulated cyclin E1 protein levels. However, hypoxia had no effect on the protein expression levels of cyclin-dependent kinase 2, 4, and 6. Chemical inhibition of hypoxia-inducible factor (HIF)-2 reduced hypoxia-induced fibroblast proliferation. Moreover, silencing of Nuclear Factor Activated T cell (NFAT) c2 attenuated the hypoxia-mediated fibroblasts proliferation. Hypoxia also induced the nuclear translocation of NFATc2, as determined by immunofluorescence staining. NFAT reporter assays showed that hypoxia-induced NFAT signaling activation is dependent on HIF-2, but not HIF-1. Furthermore, the inhibition or silencing of HIF-2, but not HIF-1, reduced the hypoxia-mediated NFATc2 nuclear translocation. Our studies suggest that hypoxia induces the proliferation of human pulmonary fibroblasts through NFAT signaling and HIF-2.

Naïve Induced Pluripotent Stem Cells Generated From β-Thalassemia Fibroblasts Allow Efficient Gene Correction With CRISPR/Cas9.

PubMed

Yang, Yuanyuan; Zhang, Xiaobai; Yi, Li; Hou, Zhenzhen; Chen, Jiayu; Kou, Xiaochen; Zhao, Yanhong; Wang, Hong; Sun, Xiao-Fang; Jiang, Cizhong; Wang, Yixuan; Gao, Shaorong

2016-01-01

Conventional primed human embryonic stem cells and induced pluripotent stem cells (iPSCs) exhibit molecular and biological characteristics distinct from pluripotent stem cells in the naïve state. Although naïve pluripotent stem cells show much higher levels of self-renewal ability and multidifferentiation capacity, it is unknown whether naïve iPSCs can be generated directly from patient somatic cells and will be superior to primed iPSCs. In the present study, we used an established 5i/L/FA system to directly reprogram fibroblasts of a patient with β-thalassemia into transgene-free naïve iPSCs with molecular signatures of ground-state pluripotency. Furthermore, these naïve iPSCs can efficiently produce cross-species chimeras. Importantly, using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 nuclease genome editing system, these naïve iPSCs exhibit significantly improved gene-correction efficiencies compared with the corresponding primed iPSCs. Furthermore, human naïve iPSCs could be directly generated from noninvasively collected urinary cells, which are easily acquired and thus represent an excellent cell resource for further clinical trials. Therefore, our findings demonstrate the feasibility and superiority of using patient-specific iPSCs in the naïve state for disease modeling, gene editing, and future clinical therapy. In the present study, transgene-free naïve induced pluripotent stem cells (iPSCs) directly converted from the fibroblasts of a patient with β-thalassemia in a defined culture system were generated. These naïve iPSCs, which show ground-state pluripotency, exhibited significantly improved single-cell cloning ability, recovery capacity, and gene-targeting efficiency compared with conventional primed iPSCs. These results provide an improved strategy for personalized treatment of genetic diseases such as β-thalassemia. ©AlphaMed Press.

Naïve Induced Pluripotent Stem Cells Generated From β-Thalassemia Fibroblasts Allow Efficient Gene Correction With CRISPR/Cas9

PubMed Central

Yang, Yuanyuan; Zhang, Xiaobai; Yi, Li; Hou, Zhenzhen; Chen, Jiayu; Kou, Xiaochen; Zhao, Yanhong; Wang, Hong; Sun, Xiao-Fang; Jiang, Cizhong

2016-01-01

Conventional primed human embryonic stem cells and induced pluripotent stem cells (iPSCs) exhibit molecular and biological characteristics distinct from pluripotent stem cells in the naïve state. Although naïve pluripotent stem cells show much higher levels of self-renewal ability and multidifferentiation capacity, it is unknown whether naïve iPSCs can be generated directly from patient somatic cells and will be superior to primed iPSCs. In the present study, we used an established 5i/L/FA system to directly reprogram fibroblasts of a patient with β-thalassemia into transgene-free naïve iPSCs with molecular signatures of ground-state pluripotency. Furthermore, these naïve iPSCs can efficiently produce cross-species chimeras. Importantly, using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 nuclease genome editing system, these naïve iPSCs exhibit significantly improved gene-correction efficiencies compared with the corresponding primed iPSCs. Furthermore, human naïve iPSCs could be directly generated from noninvasively collected urinary cells, which are easily acquired and thus represent an excellent cell resource for further clinical trials. Therefore, our findings demonstrate the feasibility and superiority of using patient-specific iPSCs in the naïve state for disease modeling, gene editing, and future clinical therapy. Significance In the present study, transgene-free naïve induced pluripotent stem cells (iPSCs) directly converted from the fibroblasts of a patient with β-thalassemia in a defined culture system were generated. These naïve iPSCs, which show ground-state pluripotency, exhibited significantly improved single-cell cloning ability, recovery capacity, and gene-targeting efficiency compared with conventional primed iPSCs. These results provide an improved strategy for personalized treatment of genetic diseases such as β-thalassemia. PMID:26676643

Improved throughput traction microscopy reveals pivotal role for matrix stiffness in fibroblast contractility and TGF-β responsiveness

PubMed Central

Marinković, Aleksandar; Mih, Justin D.; Park, Jin-Ah; Liu, Fei

2012-01-01

Lung fibroblast functions such as matrix remodeling and activation of latent transforming growth factor-β1 (TGF-β1) are associated with expression of the myofibroblast phenotype and are directly linked to fibroblast capacity to generate force and deform the extracellular matrix. However, the study of fibroblast force-generating capacities through methods such as traction force microscopy is hindered by low throughput and time-consuming procedures. In this study, we improved at the detail level methods for higher-throughput traction measurements on polyacrylamide hydrogels using gel-surface-bound fluorescent beads to permit autofocusing and automated displacement mapping, and transduction of fibroblasts with a fluorescent label to streamline cell boundary identification. Together these advances substantially improve the throughput of traction microscopy and allow us to efficiently compute the forces exerted by lung fibroblasts on substrates spanning the stiffness range present in normal and fibrotic lung tissue. Our results reveal that lung fibroblasts dramatically alter the forces they transmit to the extracellular matrix as its stiffness changes, with very low forces generated on matrices as compliant as normal lung tissue. Moreover, exogenous TGF-β1 selectively accentuates tractions on stiff matrices, mimicking fibrotic lung, but not on physiological stiffness matrices, despite equivalent changes in Smad2/3 activation. Taken together, these results demonstrate a pivotal role for matrix mechanical properties in regulating baseline and TGF-β1-stimulated contraction of lung fibroblasts and suggest that stiff fibrotic lung tissue may promote myofibroblast activation through contractility-driven events, whereas normal lung tissue compliance may protect against such feedback amplification of fibroblast activation. PMID:22659883

I Feel, Therefore, I Learn: The Role of Emotion in Self-Directed Learning

ERIC Educational Resources Information Center

Rager, Kathleen B.

2009-01-01

It is rare to find the emotional component of self-directed learning discussed explicitly in the literature. This lack is particularly glaring given the interest sparked by recent brain research concerning the importance of emotion in all types of learning as well as by the dramatic increase in self-directed learning in the emotionally charged…

Academic Performance and the Practice of Self-Directed Learning: The Adult Student Perspective

ERIC Educational Resources Information Center

Khiat, Henry

2017-01-01

The practice of self-directed learning is important to adult students as it allows them to learn effectively while juggling work, family and other commitments. This study set out to examine the self-directed learning characteristics present in the adult students' study process at the case university. The relationship between the adult students'…

Central Role for Dermal Fibroblasts in Skin Model Protection against Candida albicans.

PubMed

Kühbacher, Andreas; Henkel, Helena; Stevens, Philip; Grumaz, Christian; Finkelmeier, Doris; Burger-Kentischer, Anke; Sohn, Kai; Rupp, Steffen

2017-06-01

The fungal pathogen Candida albicans colonizes basically all human epithelial surfaces, including the skin. Under certain conditions, such as immunosuppression, invasion of the epithelia occurs. Not much is known about defense mechanisms against C. albicans in subepithelial layers such as the dermis. Using immune cell-supplemented 3D skin models we defined a new role for fibroblasts in the dermis and identified a minimal set of cell types for skin protection against C. albicans invasion. Dual RNA sequencing of individual host cell populations and C. albicans revealed that dermal invasion is directly impeded by dermal fibroblasts. They are able to integrate signals from the pathogen and CD4+ T cells and shift toward an antimicrobial phenotype with broad specificity that is dependent on Toll-like receptor 2 and interleukin 1β. These results highlight a central function of dermal fibroblasts for skin protection, opening new possibilities for treatment of infectious diseases. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Direction detection thresholds of passive self-motion in artistic gymnasts.

PubMed

Hartmann, Matthias; Haller, Katia; Moser, Ivan; Hossner, Ernst-Joachim; Mast, Fred W

2014-04-01

In this study, we compared direction detection thresholds of passive self-motion in the dark between artistic gymnasts and controls. Twenty-four professional female artistic gymnasts (ranging from 7 to 20 years) and age-matched controls were seated on a motion platform and asked to discriminate the direction of angular (yaw, pitch, roll) and linear (leftward-rightward) motion. Gymnasts showed lower thresholds for the linear leftward-rightward motion. Interestingly, there was no difference for the angular motions. These results show that the outstanding self-motion abilities in artistic gymnasts are not related to an overall higher sensitivity in self-motion perception. With respect to vestibular processing, our results suggest that gymnastic expertise is exclusively linked to superior interpretation of otolith signals when no change in canal signals is present. In addition, thresholds were overall lower for the older (14-20 years) than for the younger (7-13 years) participants, indicating the maturation of vestibular sensitivity from childhood to adolescence.

Self-Directed Lifelong Learning in Hybrid Learning Configurations

ERIC Educational Resources Information Center

Cremers, Petra H. M.; Wals, Arjen E. J.; Wesselink, Renate; Nieveen, Nienke; Mulder, Martin

2014-01-01

Present-day students are expected to be lifelong learners throughout their working life. Higher education must therefore prepare students to self-direct their learning beyond formal education, in real-life working settings. This can be achieved in so-called hybrid learning configurations in which working and learning are integrated. In such a…

Self-Directed Learning in Adulthood: A Literature Review.

ERIC Educational Resources Information Center

Owen, T. Ross

Self-directed learning (SDL) is among the most productive areas of research in adult education. Malcolm S. Knowles is credited with a comprehensive synthesis of adult teaching and adult learning principles. Andragogy, the art and science of helping adults learn, lies at the heart of Knowles' work. Lucy M. Guglielmino theorized regarding the…

Human gingival fibroblast response to electropolished NiTi surfaces.

PubMed

Es-Souni, Martha; Fischer-Brandies, Helge; Es-Souni, Mohammed

2007-01-01

In the present study the in vitro biocompatibility of electropolished NiTi sheets is investigated. The assessment of cytotoxic effects due to potential Ni leaching from metal sheets was performed in direct contact with primary human fibroblast cultures using the 5-bromo-2'-deoxyuridine cell proliferation assay and morphologic studies via light microscopy and scanning electron microscopy. To assess toxic effects related to Ni-ions release, cells cultured in the presence of increasing concentrations of Ni(2+) (NiSO(4).6H(2)O) served as positive controls. It is shown that while the addition of NiSO(4) caused severe proliferation decrease (approximately 80%) and morphologic damage at a concentration of 50 mg/L Ni(2+) no negative effects were observed in fibroblasts cultured in the presence of electropolished NiTi sheets. The results are discussed in terms of surface topography effects on the biocompatibility of NiTi shape memory alloys. (c) 2006 Wiley Periodicals, Inc.

Self-directed learning readiness of Asian students: students perspective on a hybrid problem based learning curriculum

PubMed Central

Susilo, Astrid P.; van Berkel, Henk

2016-01-01

Objectives To identify the student’s readiness to perform self-directed learning and the underlying factors influencing it on the hybrid problem based learning curriculum. Methods A combination of quantitative and qualitative studies was conducted in five medical schools in Indonesia. In the quantitative study, the Self Directed Learning Readiness Scale was distributed to all students in all batches, who had experience with the hybrid problem based curriculum. They were categorized into low- and high -level based on the score of the questionnaire. Three focus group discussions (low-, high-, and mixed level) were conducted in the qualitative study with six to twelve students chosen randomly from each group to find the factors influencing their self-directed learning readiness. Two researchers analysed the qualitative data as a measure of triangulation. Results The quantitative study showed only half of the students had a high-level of self-directed learning readiness, and a similar trend also occurred in each batch. The proportion of students with a high level of self-directed learning readiness was lower in the senior students compared to more junior students. The qualitative study showed that problem based learning processes, assessments, learning environment, students’ life styles, students’ perceptions of the topics, and mood, were factors influencing their self-directed learning. Conclusion A hybrid problem based curriculum may not fully affect the students’ self-directed learning. The curriculum system, teacher’s experiences, student’s background and cultural factors might contribute to the difficulties for the student’s in conducting self-directed learning. PMID:27915308

Protective effect of crocin on ultraviolet B‑induced dermal fibroblast photoaging.

PubMed

Deng, Mingwu; Li, Dong; Zhang, Yichen; Zhou, Guangdong; Liu, Wei; Cao, Yilin; Zhang, Wenjie

2018-06-11

Ultraviolet B (UVB) radiation induces the production of reactive oxygen species (ROS), resulting in the aging of dermal fibroblasts. Crocin, a bioactive constituent of Crocus sativus, possesses anti‑oxidation effects. The purpose of the present study was to evaluate the protective effect of crocin on UVB‑induced dermal fibroblast photoaging. Human dermal fibroblasts were isolated and cultured with different concentrations of crocin prior to and following exposure to UVB irradiation. The senescent phenotypes of cells were evaluated, including cell proliferation, cell cycle, senescence‑associated β‑galactosidase (SA‑β‑gal) expression, intracellular ROS, expression of antioxidant protein glutathione peroxidase 1 (GPX‑1) and extracellular matrix protein collagen type 1 (Col‑1). Crocin rescued the cell proliferation inhibited by UVB irradiation, prevented cell cycle arrest and markedly decreased the number of SA‑β‑gal‑positive cells. In addition, crocin reduced UVB‑induced ROS by increasing GPX‑1 expression and other direct neutralization effects. Furthermore, crocin promoted the expression of the extracellular matrix protein Col‑1. Crocin could effectively prevent UVB‑induced cell damage via the reduction of intracellular ROS; thus, it could potentially be used in the prevention of skin photoaging.

Lysophosphatidic acid signaling through its receptor initiates profibrotic epithelial cell fibroblast communication mediated by epithelial cell derived connective tissue growth factor.

PubMed

Sakai, Norihiko; Chun, Jerold; Duffield, Jeremy S; Lagares, David; Wada, Takashi; Luster, Andrew D; Tager, Andrew M

2017-03-01

The expansion of the fibroblast pool is a critical step in organ fibrosis, but the mechanisms driving expansion remain to be fully clarified. We previously showed that lysophosphatidic acid (LPA) signaling through its receptor LPA 1 expressed on fibroblasts directly induces the recruitment of these cells. Here we tested whether LPA-LPA 1 signaling drives fibroblast proliferation and activation during the development of renal fibrosis. LPA 1 -deficient (LPA 1 -/- ) or -sufficient (LPA 1 +/+ ) mice were crossed to mice with green fluorescent protein expression (GFP) driven by the type I procollagen promoter (Col-GFP) to identify fibroblasts. Unilateral ureteral obstruction-induced increases in renal collagen were significantly, though not completely, attenuated in LPA 1 -/- Col-GFP mice, as were the accumulations of both fibroblasts and myofibroblasts. Connective tissue growth factor was detected mainly in tubular epithelial cells, and its levels were suppressed in LPA 1 -/- Col-GFP mice. LPA-LPA 1 signaling directly induced connective tissue growth factor expression in primary proximal tubular epithelial cells, through a myocardin-related transcription factor-serum response factor pathway. Proximal tubular epithelial cell-derived connective tissue growth factor mediated renal fibroblast proliferation and myofibroblast differentiation. Administration of an inhibitor of myocardin-related transcription factor/serum response factor suppressed obstruction-induced renal fibrosis. Thus, targeting LPA-LPA 1 signaling and/or myocardin-related transcription factor/serum response factor-induced transcription could be promising therapeutic strategies for renal fibrosis. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Matrix metalloproteinase inhibition reduces contraction by dupuytren fibroblasts.

PubMed

Townley, William A; Cambrey, Alison D; Khaw, Peng T; Grobbelaar, Adriaan O

2008-11-01

Dupuytren's disease is a common fibroproliferative condition of the hand characterized by fibrotic lesions (nodules and cords), leading to disability through progressive digital contracture. Although the etiology of the disease is poorly understood, recent evidence suggests that abnormal matrix metalloproteinase (MMP) activity may play a role in cell-mediated collagen contraction and tissue scarring. The aim of this study was to investigate the efficacy of ilomastat, a broad-spectrum MMP inhibitor, in an in vitro model of Dupuytren fibroblast-mediated contraction. Nodule-derived and cord-derived fibroblasts were isolated from Dupuytren patients; carpal ligament-derived fibroblasts acted as control. Stress-release fibroblast-populated collagen lattices (FPCLs) were used as a model of contraction. FPCLs were allowed to develop mechanical stress (48 hours) during treatment with ilomastat (0-100 micromol/L), released, and allowed to contract over a 48-hour period. Contraction was estimated by measuring lattice area compared with untreated cells or treatment with a control peptide. MMP-1, MMP-2, and MT1-MMP levels were assessed by zymography, Western blotting, and enzyme-linked immunosorbent assay. Nodule-derived fibroblasts contracted lattices (69% +/- 2) to a greater extent than did cord-derived (55% +/- 3) or carpal ligament-derived (55% +/- 1) fibroblasts. Exposure to ilomastat led to significant inhibition of lattice contraction by all fibroblasts, although a reduction in lattice contraction by nodule-derived fibroblasts was most prominent (84% +/- 8). In addition, treatment with ilomastat led to a concomitant suppression of MMP-1 and MMP-2 activity, whereas MT1-MMP activity was found to be upregulated. Our results demonstrate that inhibition of MMP activity results in a reduction in extracellular matrix contraction by Dupuytren fibroblasts and suggest that MMP activity may be a critical target in preventing recurrent contracture caused by this disease.

Self Assembled Bi-functional Peptide Hydrogels with Biomineralization-Directing Peptides

PubMed Central

Gungormus, Mustafa; Branco, Monica; Fong, Hanson; Schneider, Joel P.; Tamerler, Candan; Sarikaya, Mehmet

2014-01-01

A peptide-based hydrogel has been designed that directs the formation of hydroxyapatite. MDG1, a twenty-seven residue peptide, undergoes triggered folding to form an unsymmetrical β-hairpin that self-assembles in response to an increase in solution ionic strength to yield a mechanically rigid, self supporting hydrogel. The C-terminal portion of MDG1 contains a heptapeptide (MLPHHGA) capable of directing the mineralization process. Circular dichroism spectroscopy indicates that the peptide folds and assembles to form a hydrogel network rich in β-sheet secondary structure. Oscillatory rheology indicates that the hydrogel is mechanical rigid (G′ ∼ 2500 Pa) before mineralization. In separate experiments, mineralization was induced both biochemically and with cementoblast cells. Mineralization-domain had little effect on the mechanical rigidity of the gel. SEM and EDS show that MDG1 gels are capable of directing the formation of hydroxapatite. Control hydrogels, prepared by peptides either lacking the mineral-directing portion or reversing its sequence, indicated that the heptapeptide is necessary and its actions are sequence specific. PMID:20591477

Self-directed learning readiness and learning styles among Saudi undergraduate nursing students.

PubMed

El-Gilany, Abdel-Hady; Abusaad, Fawzia El Sayed

2013-09-01

Self-directed learning has become a focus for nursing education in the past few decades due to the complexity and changes in nursing profession development. On the other hand, the Kolb's learning style could identify student's preference for perceiving and processing information. This study was performed to determine Saudi nursing students' readiness for self-directed learning; to identify their learning styles and to find out the relation between these two concepts. Cross-sectional descriptive study. Nursing department of faculty of Applied Medical Sciences, Al-Jouf University, Saudi Arabia. Two hundred and seventy-five undergraduate Saudi nursing students. Data was collected using self-administered questionnaires covering the demographic features of students, Fisher's self-directed learning readiness (SDLR) scale, and the Kolb's learning styles inventory. The mean scores of self-management, desire for learning, self-control and the overall SDLR were 51.3 ± 5.9, 48.4 ± 5.5, 59.9 ± 6.7, and 159.6 ± 13.8; respectively. About 77% (211) of students have high level of SDLR. The percentages of converger, diverger, assimilator and accommodator learning styles are 35.6%, 25.8%, 25.55% and 13.1%; respectively. The mean score of self-management, desire for learning, self-control and overall SDLR scale did not vary with any of the studied variables. There is no association between the level of SDLR and the learning styles. The high level of SDLR and the dominant converger learning style among undergraduate nursing students will have a positive implication for their education and post-employment continuing nursing education. Copyright © 2012 Elsevier Ltd. All rights reserved.

Consumer direction in long-term care policy: overcoming barriers to promoting older adults' opportunity for self-direction.

PubMed

Ruggiano, Nicole

2012-01-01

There has been a growing trend in long-term care policy to offer individuals with disabilities the option of consumer direction (CD), where responsibility of managing care and support services is transferred from agencies to care recipients, thus supporting clients' self-determination. Although CD has been accepted as an option for non-elderly individuals with disabilities, barriers persist to promoting older adults' autonomy through CD. This article reviews the incorporation of CD in long-term care policy, addresses the current barriers to providing older adults the right to self-direct, and makes recommendations for overcoming these barriers through social work practice, policy, and research.

An Automated Design Framework for Multicellular Recombinase Logic.

PubMed

Guiziou, Sarah; Ulliana, Federico; Moreau, Violaine; Leclere, Michel; Bonnet, Jerome

2018-05-18

Tools to systematically reprogram cellular behavior are crucial to address pressing challenges in manufacturing, environment, or healthcare. Recombinases can very efficiently encode Boolean and history-dependent logic in many species, yet current designs are performed on a case-by-case basis, limiting their scalability and requiring time-consuming optimization. Here we present an automated workflow for designing recombinase logic devices executing Boolean functions. Our theoretical framework uses a reduced library of computational devices distributed into different cellular subpopulations, which are then composed in various manners to implement all desired logic functions at the multicellular level. Our design platform called CALIN (Composable Asynchronous Logic using Integrase Networks) is broadly accessible via a web server, taking truth tables as inputs and providing corresponding DNA designs and sequences as outputs (available at http://synbio.cbs.cnrs.fr/calin ). We anticipate that this automated design workflow will streamline the implementation of Boolean functions in many organisms and for various applications.

Thinking about Bacillus subtilis as a multicellular organism.

PubMed

Aguilar, Claudio; Vlamakis, Hera; Losick, Richard; Kolter, Roberto

2007-12-01

Initial attempts to use colony morphogenesis as a tool to investigate bacterial multicellularity were limited by the fact that laboratory strains often have lost many of their developmental properties. Recent advances in elucidating the molecular mechanisms underlying colony morphogenesis have been made possible through the use of undomesticated strains. In particular, Bacillus subtilis has proven to be a remarkable model system to study colony morphogenesis because of its well-characterized developmental features. Genetic screens that analyze mutants defective in colony morphology have led to the discovery of an intricate regulatory network that controls the production of an extracellular matrix. This matrix is essential for the development of complex colony architecture characterized by aerial projections that serve as preferential sites for sporulation. While much progress has been made, the challenge for future studies will be to determine the underlying mechanisms that regulate development such that differentiation occurs in a spatially and temporally organized manner.

Neural Correlates of Direct and Reflected Self-Appraisals in Adolescents and Adults: When Social Perspective-Taking Informs Self-Perception

ERIC Educational Resources Information Center

Pfeifer, Jennifer H.; Masten, Carrie L.; Borofsky, Larissa A.; Dapretto, Mirella; Fuligni, Andrew J.; Lieberman, Matthew D.

2009-01-01

Classic theories of self-development suggest people define themselves in part through internalized perceptions of other people's beliefs about them, known as reflected self-appraisals. This study uses functional magnetic resonance imaging to compare the neural correlates of direct and reflected self-appraisals in adolescence (N = 12, ages 11-14…

Early Childhood Media Exposure and Self-Regulation: Bi-Directional Longitudinal Associations.

PubMed

Cliff, Dylan P; Howard, Steven J; Radesky, Jenny S; McNeill, Jade; Vella, Stewart A

2018-04-26

To investigate: i) prospective associations between media exposure (television viewing, computers, and electronic games) at 2 years and self-regulation at 4 and 6 years, and ii) bi-directional associations between media exposure and self-regulation at 4 and 6 years. We hypothesized that media exposure and self-regulation would display a negative prospective association and subsequent bi-directional inverse associations. Data from the nationally-representative Longitudinal Study of Australian Children (LSAC) when children were aged 2 (n=2786) and 4/6 years (n=3527) were used. Primary caregivers reported children's weekly electronic media exposure. A composite measure of self-regulation was computed from caregivers-, teacher-, and observer-report data. Associations were examined using linear regression and cross-lagged panel models, accounting for covariates. Lower television viewing and total media exposure at 2 years were associated with higher self-regulation at 4 years (both β -0.02; 95% confidence interval [CI] -0.03, -0.01). Lower self-regulation at 4 years was also significantly associated with higher television viewing (β -0.15; 95% CI -0.21, -0.08), electronic game use (β -0.05; 95% CI -0.09, -0.01), and total media exposure (β -0.19; 95% CI -0.29, -0.09) at 6 years. However, media exposure at 4 years was not associated with self-regulation at 6 years. Although media exposure duration at 2 years was associated with later self-regulation, and self-regulation at 4 years was associated with later media exposure, associations were of small magnitude. More research is needed examining content quality, social context, and mobile media use and child self-regulation. Copyright © 2018. Published by Elsevier Inc.

Normal Human Fibroblasts Are Resistant to RAS-Induced Senescence

PubMed Central

Benanti, Jennifer A.; Galloway, Denise A.

2004-01-01

Oncogenic stimuli are thought to induce senescence in normal cells in order to protect against transformation and to induce proliferation in cells with altered p53 and/or retinoblastoma (Rb) pathways. In human fibroblasts, RAS initiates senescence through upregulation of the cyclin-dependent kinase inhibitor p16INK4A. We show here that in contrast to cultured fibroblast strains, freshly isolated normal fibroblasts are resistant to RAS-induced senescence and instead show some characteristics of transformation. RAS did not induce growth arrest or expression of senescence-associated β-galactosidase, and Rb remained hyperphosphorylated despite elevated levels of p16. Instead, RAS promoted anchorage-independent growth of normal fibroblasts, although expression of hTert with RAS increased colony formation and allowed normal fibroblasts to bypass contact inhibition. To test the hypothesis that p16 levels determine how cells respond to RAS, we expressed RAS in freshly isolated fibroblasts that expressed very low levels of p16, in hTert-immortalized fibroblasts that had accumulated intermediate levels of p16, and in IMR90 fibroblasts with high levels of p16. RAS induced growth arrest in cells with higher p16 levels, and this effect was reversed by p16 knockdown in the hTert-immortalized fibroblasts. These findings indicate that culture-imposed stress sensitizes cells to RAS-induced arrest, whereas early passage cells do not arrest in response to RAS. PMID:15024073

The triple helix of collagens - an ancient protein structure that enabled animal multicellularity and tissue evolution.

PubMed

Fidler, Aaron L; Boudko, Sergei P; Rokas, Antonis; Hudson, Billy G

2018-04-09

The cellular microenvironment, characterized by an extracellular matrix (ECM), played an essential role in the transition from unicellularity to multicellularity in animals (metazoans), and in the subsequent evolution of diverse animal tissues and organs. A major ECM component are members of the collagen superfamily -comprising 28 types in vertebrates - that exist in diverse supramolecular assemblies ranging from networks to fibrils. Each assembly is characterized by a hallmark feature, a protein structure called a triple helix. A current gap in knowledge is understanding the mechanisms of how the triple helix encodes and utilizes information in building scaffolds on the outside of cells. Type IV collagen, recently revealed as the evolutionarily most ancient member of the collagen superfamily, serves as an archetype for a fresh view of fundamental structural features of a triple helix that underlie the diversity of biological activities of collagens. In this Opinion, we argue that the triple helix is a protein structure of fundamental importance in building the extracellular matrix, which enabled animal multicellularity and tissue evolution. © 2018. Published by The Company of Biologists Ltd.

Effects of neuropeptides on human lung fibroblast proliferation and chemotaxis.

PubMed

Harrison, N K; Dawes, K E; Kwon, O J; Barnes, P J; Laurent, G J; Chung, K F

1995-02-01

An increase in subepithelial mesenchymal cells and associated connective tissue is a feature of bronchial asthma. We determined whether neuropeptides could modulate fibroblast activity, particularly with respect to proliferation and chemotaxis. Human lung fibroblasts were cultured with neurokinin A (NKA), substance P (SP), vasoactive intestinal peptide (VIP), and calcitonin-gene-related peptide (CGRP). After 48 h, fibroblast proliferation was measured by a colorimetric assay based on the uptake and subsequent release of methylene blue. The chemotactic response to neuropeptides was determined with the use of a modified Boyden chamber. Both NKA and SP (10(-7)-10(-4) M) stimulated human lung fibroblast proliferation in HFL1 and IMR-90 fibroblasts. VIP and CGRP had no effect on fibroblast proliferation. NKA alone stimulated fibroblast chemotaxis maximally at 10(-10) M. Neutral endopeptidase (NEP) activity of 0.52 and 5.2 pmol/10(6) cells was assayed in IMR-90 and Hs68 fibroblasts, respectively. Phosphoramidon (5 x 10(-6)-10(-5) M), an NEP inhibitor, enhanced fibroblast proliferation in a dose-dependent manner. Thus neuropeptides have the potential to cause activation of mesenchymal cells, and neuropeptide release may contribute to the structural abnormalities observed in asthmatic airways.

Physiologically activated mammary fibroblasts promote postpartum mammary cancer

PubMed Central

Guo, Qiuchen; Burchard, Julja; Spellman, Paul

2017-01-01

Women diagnosed with breast cancer within 5 years of childbirth have poorer prognosis than nulliparous or pregnant women. Weaning-induced breast involution is implicated, as the collagen-rich, immunosuppressive microenvironment of the involuting mammary gland is tumor promotional in mice. To investigate the role of mammary fibroblasts, isolated mammary PDGFRα+ cells from nulliparous and postweaning mice were assessed for activation phenotype and protumorigenic function. Fibroblast activation during involution was evident by increased expression of fibrillar collagens, lysyl oxidase, Tgfb1, and Cxcl12 genes. The ability of mammary tumors to grow in an isogenic, orthotopic transplant model was increased when tumor cells were coinjected with involution-derived compared with nulliparous-derived mammary fibroblasts. Mammary tumors in the involution-fibroblast group had increased Ly6C+ monocytes at the tumor border, and decreased CD8+ T cell infiltration and tumor cell death. Ibuprofen treatment suppressed involution-fibroblast activation and tumor promotional capacity, concurrent with decreases in tumor Ly6C+ monocytes, and increases in intratumoral CD8+ T cell infiltration, granzyme levels, and tumor cell death. In total, our data identify a COX/prostaglandin E2 (PGE2)–dependent activated mammary fibroblast within the involuting mammary gland that displays protumorigenic, immunosuppressive activity, identifying fibroblasts as potential targets for the prevention and treatment of postpartum breast cancer. PMID:28352652

Assessing readiness for self-directed learning within a non-traditional nursing cohort.

PubMed

Phillips, Brian N; Turnbull, Beverley J; He, Flora X

2015-03-01

Increasing deregulation of the Australian tertiary system has led to changes in entry behaviours anticipated in non-traditional student cohorts. Many nursing students are returning to formal studies later in their lives seeking a career change. Accessibility and flexible study paths make external study increasingly attractive. However external studies require a level of commitment and willingness to develop self-direction and a capacity for resilience. This study sought to elicit the level of self-directed learning readiness (SDLR) among undergraduate nursing students currently enrolled at a bachelor level, and to elicit what differences existed in the levels of SDLR in relation to age, gender, academic year, and previous qualifications. An online survey questionnaire was utilised based on the Self-directed Learning Readiness Scale for Nursing Education. In contrast to earlier work, the participant profile in this study was predominantly non-traditional and captured participants from all three years of the nursing programme. Results found no significant age or gender differences. First year students demonstrated lower levels of self-directed learning readiness. However, unexpected results were demonstrated in the survey subscales in relation to previous qualifications. Participants who already held post-graduate qualifications showed lower scores for Self-Management than those who held diploma qualifications, while students who already held a bachelor's degree had the highest scores in Desire for Learning. The study findings suggest that universities should not assume that SDL capability is dependent on mature age or length of exposure to tertiary study. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cell-like pressure sensors reveal increase of mechanical stress towards the core of multicellular spheroids under compression.

PubMed

Dolega, M E; Delarue, M; Ingremeau, F; Prost, J; Delon, A; Cappello, G

2017-01-27

The surrounding microenvironment limits tumour expansion, imposing a compressive stress on the tumour, but little is known how pressure propagates inside the tumour. Here we present non-destructive cell-like microsensors to locally quantify mechanical stress distribution in three-dimensional tissue. Our sensors are polyacrylamide microbeads of well-defined elasticity, size and surface coating to enable internalization within the cellular environment. By isotropically compressing multicellular spheroids (MCS), which are spherical aggregates of cells mimicking a tumour, we show that the pressure is transmitted in a non-trivial manner inside the MCS, with a pressure rise towards the core. This observed pressure profile is explained by the anisotropic arrangement of cells and our results suggest that such anisotropy alone is sufficient to explain the pressure rise inside MCS composed of a single cell type. Furthermore, such pressure distribution suggests a direct link between increased mechanical stress and previously observed lack of proliferation within the spheroids core.

Collaborative and Defensive Fibroblasts in Tumor Progression and Therapy Resistance.

PubMed

Chiavarina, Barbara; Turtoi, Andrei

2017-01-01

Tumor microenvironment is a complex network of epithelial cancer cells and non-transformed stromal cells. Of the many stromal cell types, fibroblasts are the most numerous ones and are traditionally viewed as supportive elements of cancer progression. Many studies show that cancer cells engage in active crosstalk with associated fibroblasts in order to obtain key resources, such as growth factors and nutrients. The facets of fibroblast "complicity to murder" in cancer are multiple. However, recent therapeutic attempts aiming at depleting fibroblasts from tumors, perturbed rather simplistic picture. Contrary to the expectations, tumors devoid of fibroblasts accelerated their progression while patients faced poorer outcomes. These studies remind us of the physiologic roles fibroblasts have in maintaining tissue homeostasis even in the presence of cancer. It is becoming increasingly clear that our research focus on advanced tumors has biased our understanding of fibroblast role in tumor biology. The numerous events where the fibroblasts protect the tissue from malignant transformation remain largely unacknowledged, as the tumors are invisible. The present review has the ambition to offer a more balanced view of fibroblasts functions in cancer progression and therapy resistance. We will address the question whether it is possible to synergize the efforts with fibroblasts as the therapeutic concept against tumor progression and therapy resistance. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Generation of multicellular tumor spheroids by the hanging-drop method.

PubMed

Timmins, Nicholas E; Nielsen, Lars K

2007-01-01

Owing to their in vivo-like characteristics, three-dimensional (3D) multicellular tumor spheroid (MCTS) cultures are gaining increasing popularity as an in vitro model of tumors. A straightforward and simple approach to the cultivation of these MCTS is the hanging-drop method. Cells are suspended in droplets of medium, where they develop into coherent 3D aggregates and are readily accessed for analysis. In addition to being simple, the method eliminates surface interactions with an underlying substratum (e.g., polystyrene plastic or agarose), requires only a low number of starting cells, and is highly reproducible. This method has also been applied to the co-cultivation of mixed cell populations, including the co-cultivation of endothelial cells and tumor cells as a model of early tumor angiogenesis.

A self-sensing active magnetic bearing based on a direct current measurement approach.

PubMed

Niemann, Andries C; van Schoor, George; du Rand, Carel P

2013-09-11

Active magnetic bearings (AMBs) have become a key technology in various industrial applications. Self-sensing AMBs provide an integrated sensorless solution for position estimation, consolidating the sensing and actuating functions into a single electromagnetic transducer. The approach aims to reduce possible hardware failure points, production costs, and system complexity. Despite these advantages, self-sensing methods must address various technical challenges to maximize the performance thereof. This paper presents the direct current measurement (DCM) approach for self-sensing AMBs, denoting the direct measurement of the current ripple component. In AMB systems, switching power amplifiers (PAs) modulate the rotor position information onto the current waveform. Demodulation self-sensing techniques then use bandpass and lowpass filters to estimate the rotor position from the voltage and current signals. However, the additional phase-shift introduced by these filters results in lower stability margins. The DCM approach utilizes a novel PA switching method that directly measures the current ripple to obtain duty-cycle invariant position estimates. Demodulation filters are largely excluded to minimize additional phase-shift in the position estimates. Basic functionality and performance of the proposed self-sensing approach are demonstrated via a transient simulation model as well as a high current (10 A) experimental system. A digital implementation of amplitude modulation self-sensing serves as a comparative estimator.

Self-Directed Learning Readiness among Undergraduate Students at Saudi Electronic University in Saudi Arabia

ERIC Educational Resources Information Center

Alfaifi, Mousa S.

2016-01-01

This study aimed to determine the level of self-directed learning readiness (SDLR) among undergraduate students at Saudi Electronic University in Saudi Arabia. Also, investigated were potential relationships between the level of self-directed learning readiness and selected demographic variables such as gender and specific college within the…

Small molecule targeting of the actin associating protein tropomyosin Tpm3.1 increases neuroblastoma cell response to Rac inhibition of multicellular invasion.

PubMed

Mitchell, Camilla B; Stehn, Justine R; O'Neill, Geraldine M

2018-05-12

The migration and invasion of cells through tissues in the body is facilitated by a dynamic actin cytoskeleton. The actin-associating protein, tropomyosin Tpm3.1 has emerged to play important roles in cell migration and invasion. To date, investigations have focused on single cell migration and invasion where Tpm3.1 expression is inversely associated with Rac GTPase-mediated cell invasion. While single cell and collective cell invasion have many features in common, collective invasion is additionally impacted by cell-cell adhesion, and the role of Tpm3.1 in collective invasion has not been established. In the present study we have modelled multicellular invasion using neuroblastoma spheroids embedded in 3D collagen and analysed the function of Tpm3.1 using recently established compounds that target the Tpm3.1 C-terminus. The major findings from our study reveal that combined Rac inhibition and Tpm3.1 targeting result in greater inhibition of multicellular invasion than either treatment alone. Together, the data suggest that Tpm3.1 disruption sensitizes neuroblastoma cells to Rac inhibition of multicellular invasion. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

CARFMAP: A Curated Pathway Map of Cardiac Fibroblasts.

PubMed

Nim, Hieu T; Furtado, Milena B; Costa, Mauro W; Kitano, Hiroaki; Rosenthal, Nadia A; Boyd, Sarah E

2015-01-01

The adult mammalian heart contains multiple cell types that work in unison under tightly regulated conditions to maintain homeostasis. Cardiac fibroblasts are a significant and unique population of non-muscle cells in the heart that have recently gained substantial interest in the cardiac biology community. To better understand this renaissance cell, it is essential to systematically survey what has been known in the literature about the cellular and molecular processes involved. We have built CARFMAP (http://visionet.erc.monash.edu.au/CARFMAP), an interactive cardiac fibroblast pathway map derived from the biomedical literature using a software-assisted manual data collection approach. CARFMAP is an information-rich interactive tool that enables cardiac biologists to explore the large body of literature in various creative ways. There is surprisingly little overlap between the cardiac fibroblast pathway map, a foreskin fibroblast pathway map, and a whole mouse organism signalling pathway map from the REACTOME database. Among the use cases of CARFMAP is a common task in our cardiac biology laboratory of identifying new genes that are (1) relevant to cardiac literature, and (2) differentially regulated in high-throughput assays. From the expression profiles of mouse cardiac and tail fibroblasts, we employed CARFMAP to characterise cardiac fibroblast pathways. Using CARFMAP in conjunction with transcriptomic data, we generated a stringent list of six genes that would not have been singled out using bioinformatics analyses alone. Experimental validation showed that five genes (Mmp3, Il6, Edn1, Pdgfc and Fgf10) are differentially regulated in the cardiac fibroblast. CARFMAP is a powerful tool for systems analyses of cardiac fibroblasts, facilitating systems-level cardiovascular research.

Effects of polyhexamethylene guanidine phosphate on human gingival fibroblasts.

PubMed

Vitt, Anton; Slizen, Veronica; Boström, Elisabeth A; Yucel-Lindberg, Tülay; Kats, Anna; Sugars, Rachael V; Gustafsson, Anders; Buhlin, Kåre

2017-10-01

Polyhexamethylene guanidine phosphate (PHMG-P) was compared to chlorhexidine (CHX) in order to determine potential cytotoxic and immune-modulatory effects on human gingival fibroblasts. Cytotoxic effects of PHMG-P and CHX on human gingival fibroblasts were assessed using cell viability assay at various time points and concentrations. The effects of PHMG-P and CHX on the secretion of prostaglandin (PG) E 2 , interleukin (IL)-6, IL-8 and matrix metalloproteinase (MMP)-1 by non-stimulated or IL-1β stimulated fibroblasts were evaluated by enzyme-linked immunosorbent assays. PHMG-P concentration 0.00009% led to the total loss of fibroblast viability within 24 h, whereas inhibition of fibroblast viability by CHX occurred at significantly higher concentrations of 0.0009% (p < .001). Short-term exposure to 0.005% PHMG-P led to loss of fibroblast viability after 5 min, whilst cells exposed to 0.005% CHX survived 30 min of treatment (p < .001). IL-1β stimulation induced an inflammatory response with a significant increase in the secretion of PGE 2 , IL-6, IL-8 and MMP-1. Treatment of IL-1β stimulated fibroblasts in combination with PHMG-P or CHX at concentrations of 0.000045 or 0.0.00009% resulted in significantly decreased PGE 2 , IL-6, IL-8 and MMP-1 levels. PHMG-P or CHX alone did not affect the baseline secretion of PGE 2 , IL-6, IL-8 or MMP-1 by gingival fibroblasts. Cytotoxic effects on gingival fibroblasts were triggered by both PHMG-P and CHX at concentrations below those used in clinical practice. The tested antiseptics did not cause inflammation and reduced IL-1β-induced secretion of inflammatory mediators and collagenase by gingival fibroblasts, which suggests anti-inflammatory properties.

AGEs trigger autophagy in diabetic skin tissues and fibroblasts.

PubMed

Sun, Kan; Wang, Wei; Wang, Chuan; Lao, Guojuan; Liu, Dan; Mai, Lifang; Yan, Li; Yang, Chuan; Ren, Meng

2016-03-11

Accumulation of advanced glycation end products (AGEs) contributes to the development of diabetic ulcers. Recent evidence indicates that AGEs administration enhanced autophagy in many cell types. As a positive trigger of autophagy, the effect of AGEs on autophagy in skin tissues and fibroblasts remains unknown. Skin tissues were isolated from Spreqne-Dawley rats and immunohistochemical staining was performed to analyze the location of LC3 and FOXO1 in skin tissues. Then primary cultured foreskin fibroblast cells with treated with AGEs and the effect of AGEs on autophagy was investigated. Protein level expressions of LC3, Beclin-1 and FOXO1 in fibroblasts were analyzed by Western blotting. Autophagic flux is detected with autophagy inhibitor chloroquine and mRFP-GFP-LC3 tandem construct. Compared with skin from normal rats, immunohistochemical staining shows a predominant LC3 localization in fibroblasts cytoplasm in diabetic rats. Elevated expression of FOXO1 also existed in diabetic rats dermis fibroblasts when compared with normal rats in immunohistochemical analysis. In human skin fibroblasts cells, AGEs administration stimulated the autophagy related LC3-II/LC3-I and Beclin-1 expressions and increased autophagy flux. In mRFP-GFP-LC3 puncta formation assays, both autolysosome and autophagosome were increased in human fibroblasts after treatment with AGEs. Fibroblasts exposed to AGEs also have increased FOXO1 expression compared with control group. AGEs could induce autophagy at least in part via regulating the FOXO1 activity in diabetic skin tissues and fibroblasts. Copyright © 2016 Elsevier Inc. All rights reserved.

The intersection of interpersonal and self-directed violence among general adult, college student and sexually diverse samples.

PubMed

Cramer, Robert J; Desmarais, Sarah L; Johnson, Kiersten L; Gemberling, Tess M; Nobles, Matt R; Holley, Sarah R; Wright, Susan; Van Dorn, Richard

2017-02-01

Suicide and interpersonal violence (i.e. victimization and perpetration) represent pressing public health problems, and yet remain mostly addressed as separate topics. To identify the (1) frequency and overlap of suicide and interpersonal violence and (2) characteristics differentiating subgroups of violence-related experiences. A health survey was completed by 2,175 respondents comprised of three groups: college students ( n = 702), adult members of a sexuality special interest organization ( n = 816) and a community adult sample ( n = 657). Latent class analysis was used to identify subgroups characterized by violence experiences; logistic regression was used to identify respondent characteristics differentiating subgroups. Overall rates of violence perpetration were low; perpetration, victimization and self-directed violence all varied by sample. Adults with alternative sexual interests reported high rates of victimization and self-directed violence. Analyses indicated two subgroups: (1) victimization + self-directed violence and (2) self-directed violence only. The victimization + self-directed violence subgroup was characterized by older, White, female and sexual orientation minority persons. The self-directed violence subgroup was characterized by younger, non-White, male and straight counterparts engaging with more sexual partners and more frequent drug use. Findings support the Centers for Disease Control and Prevention (CDC) definition of suicide as self-directed violence. Suicide intervention and prevention should further account for the role of violent victimization by focusing on the joint conceptualization of self-directed and interpersonal violence. Additional prevention implications are discussed.

Applying Case-Based Method in Designing Self-Directed Online Instruction: A Formative Research Study

ERIC Educational Resources Information Center

Luo, Heng; Koszalka, Tiffany A.; Arnone, Marilyn P.; Choi, Ikseon

2018-01-01

This study investigated the case-based method (CBM) instructional-design theory and its application in designing self-directed online instruction. The purpose of this study was to validate and refine the theory for a self-directed online instruction context. Guided by formative research methodology, this study first developed an online tutorial…

SKOLAR MD: A Model for Self-Directed, In-Context Continuing Medical Education