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Sample records for ai cell formation

  1. Cholesterol Efflux Capacity of Apolipoprotein A-I Varies with the Extent of Differentiation and Foam Cell Formation of THP-1 Cells

    PubMed Central

    Yano, Kouji; Sato, Megumi; Yoshimoto, Akira; Ichimura, Naoya; Kameda, Takahiro; Kubota, Tetsuo

    2016-01-01

    Apolipoprotein A-I (apoA-I), the main protein component of high-density lipoprotein (HDL), has many protective functions against atherosclerosis, one of them being cholesterol efflux capacity. Although cholesterol efflux capacity measurement is suggested to be a key biomarker for evaluating the risk of development of atherosclerosis, the assay has not been optimized till date. This study aims at investigating the effect of different states of cells on the cholesterol efflux capacity. We also studied the effect of apoA-I modification by homocysteine, a risk factor for atherosclerosis, on cholesterol efflux capacity in different states of cells. The cholesterol efflux capacity of apoA-I was greatly influenced by the extent of differentiation of THP-1 cells and attenuated by excessive foam cell formation. N-Homocysteinylated apoA-I indicated a lower cholesterol efflux capacity than normal apoA-I in the optimized condition, whereas no significant difference was observed in the cholesterol efflux capacity between apoA-I in the excessive cell differentiation or foam cell formation states. These results suggest that cholesterol efflux capacity of apoA-I varies depending on the state of cells. Therefore, the cholesterol efflux assay should be performed using protocols optimized according to the objective of the experiment. PMID:27957343

  2. AI-2 of Aggregatibacter actinomycetemcomitans inhibits Candida albicans biofilm formation.

    PubMed

    Bachtiar, Endang W; Bachtiar, Boy M; Jarosz, Lucja M; Amir, Lisa R; Sunarto, Hari; Ganin, Hadas; Meijler, Michael M; Krom, Bastiaan P

    2014-01-01

    Aggregatibacter actinomycetemcomitans, a Gram-negative bacterium, and Candida albicans, a polymorphic fungus, are both commensals of the oral cavity but both are opportunistic pathogens that can cause oral diseases. A. actinomycetemcomitans produces a quorum-sensing molecule called autoinducer-2 (AI-2), synthesized by LuxS, that plays an important role in expression of virulence factors, in intra- but also in interspecies communication. The aim of this study was to investigate the role of AI-2 based signaling in the interactions between C. albicans and A. actinomycetemcomitans. A. actinomycetemcomitans adhered to C. albicans and inhibited biofilm formation by means of a molecule that was secreted during growth. C. albicans biofilm formation increased significantly when co-cultured with A. actinomycetemcomitans luxS, lacking AI-2 production. Addition of wild-type-derived spent medium or synthetic AI-2 to spent medium of the luxS strain, restored inhibition of C. albicans biofilm formation to wild-type levels. Addition of synthetic AI-2 significantly inhibited hypha formation of C. albicans possibly explaining the inhibition of biofilm formation. AI-2 of A. actinomycetemcomitans is synthesized by LuxS, accumulates during growth and inhibits C. albicans hypha- and biofilm formation. Identifying the molecular mechanisms underlying the interaction between bacteria and fungi may provide important insight into the balance within complex oral microbial communities.

  3. Highly Effective Inhibition of Biofilm Formation by the First Metagenome-Derived AI-2 Quenching Enzyme

    PubMed Central

    Weiland-Bräuer, Nancy; Kisch, Martin J.; Pinnow, Nicole; Liese, Andreas; Schmitz, Ruth A.

    2016-01-01

    Bacterial cell–cell communication (quorum sensing, QS) represents a fundamental process crucial for biofilm formation, pathogenicity, and virulence allowing coordinated, concerted actions of bacteria depending on their cell density. With the widespread appearance of antibiotic-resistance of biofilms, there is an increasing need for novel strategies to control harmful biofilms. One attractive and most likely effective approach is to target bacterial communication systems for novel drug design in biotechnological and medical applications. In this study, metagenomic large-insert libraries were constructed and screened for QS interfering activities (quorum quenching, QQ) using recently established reporter strains. Overall, 142 out of 46,400 metagenomic clones were identified to interfere with acyl-homoserine lactones (AHLs), 13 with autoinducer-2 (AI-2). Five cosmid clones with highest simultaneous interfering activities were further analyzed and the respective open reading frames conferring QQ activities identified. Those showed homologies to bacterial oxidoreductases, proteases, amidases and aminotransferases. Evaluating the ability of the respective purified QQ-proteins to prevent biofilm formation of several model systems demonstrated highest inhibitory effects of QQ-2 using the crystal violet biofilm assay. This was confirmed by heterologous expression of the respective QQ proteins in Klebsiella oxytoca M5a1 and monitoring biofilm formation in a continuous flow cell system. Moreover, QQ-2 chemically immobilized to the glass surface of the flow cell effectively inhibited biofilm formation of K. oxytoca as well as clinical K. pneumoniae isolates derived from patients with urinary tract infections. Indications were obtained by molecular and biochemical characterizations that QQ-2 represents an oxidoreductase most likely reducing the signaling molecules AHL and AI-2 to QS-inactive hydroxy-derivatives. Overall, we propose that the identified novel QQ-2 protein

  4. AI-2/LuxS is involved in increased biofilm formation by Streptococcus intermedius in the presence of antibiotics.

    PubMed

    Ahmed, Nibras A; Petersen, Fernanda C; Scheie, Anne A

    2009-10-01

    Bacteria utilize quorum-sensing communication to organize their behavior by monitoring the concentration of bacterial signals, referred to as autoinducers (AIs). The widespread detection of AI-2 signals and its enzymatic synthase (LuxS) in bacteria suggests that AI-2 is an inter- and intraspecies communication signal. We have previously shown that antibiotic susceptibility is affected by AI-2 signaling in Streptococcus anginosus. Since chronic infections involve persistent biofilms resilient to antibiotic treatment, we explored the role of AI-2/LuxS in Streptococcus intermedius biofilm formation and cell viability when the organism was exposed to sub-MICs of ampicillin, ciprofloxacin, or tetracycline. The S. intermedius wild type (WT) and its isogenic luxS mutant, strain SI006, were exposed to sub-MICs of ampicillin, ciprofloxacin, or tetracycline. Biofilms were formed on polystyrene discs in microtiter plates. To assess planktonic cell viability, the ATP microbial viability assay was performed and the numbers of CFU were determined. For complementation assays, the AI-2 precursor dihydroxy pentanedione (DPD) was used as a supplement for SI006. Relative luxS expression was quantified by real-time PCR. The sub-MICs of all three antibiotics increased biofilm formation in S. intermedius WT. However, biofilm formation by SI006 was either unaffected or reduced (P < or = 0.05). Bacterial viability tests of biofilm and planktonic cell cultures indicated that SI006 was more susceptible to antibiotics than the WT. DPD complemented the luxS mutant phenotype. Real-time PCR revealed modest yet significant changes in luxS expression in the presence of antibiotic concentrations that increased biofilm formation. In conclusion, in S. intermedius, AI-2/LuxS was involved in antibiotic susceptibility and increased biofilm formation at sub-MICs of antibiotic.

  5. Regulation of the promoter of rat apolipoprotein A-I gene in cultured cells

    SciTech Connect

    Chao, Y.; Pan, T.; Wu, T.; Hao, Q.; Yamin, T.; Kroon, P.A.

    1987-05-01

    In order to study the regulation of the promoter of apolipoprotein (apo) A-I gene, they joined the 5' end of rat apo A-I gene (1.9 Kb) to the coding region of bacterial chloramphenicol acetyltransferase (CAT) gene. The chimeric gene produced high levels of CAT activity in both mouse L cells and Hep G2 cells in transient expression assays. Ethanol increased the levels of rat apo A-I promoter activity in both cells. However, dexamethasone increased rat apo A-I promoter activity only in Hep G2 cells. Similar results were obtained in stable expression cell lines. Nucleotide deletion experiments showed DNA sequences between -149 and -469 base pairs upstream from the rat apo A-I transcription site are required for the high level of expression and that the regulatory sequences are located further upstream. These data demonstrated that the 5' end of rat apo A-I gene contains sequences which are responsible for the regulation of apo A-I expression by ethanol and dexamethasone and that the expression and regulation of rat apo A-I promoter are cell specific.

  6. Integration of AI-2 Based Cell-Cell Signaling with Metabolic Cues in Escherichia coli

    PubMed Central

    Mitra, Arindam; Herren, Christopher D.; Patel, Isha R.; Coleman, Adam; Mukhopadhyay, Suman

    2016-01-01

    The quorum sensing molecule Autoinducer-2 (AI-2) is generated as a byproduct of activated methyl cycle by the action of LuxS in Escherichia coli. AI-2 is synthesized, released and later internalized in a cell-density dependent manner. Here, by mutational analysis of the genes, uvrY and csrA, we describe a regulatory circuit of accumulation and uptake of AI-2. We constructed a single-copy chromosomal luxS-lacZ fusion in a luxS + merodiploid strain and evaluated its relative expression in uvrY and csrA mutants. At the entry of stationary phase, the expression of the fusion and AI-2 accumulation was positively regulated by uvrY and negatively regulated by csrA respectively. A deletion of csrA altered message stability of the luxS transcript and CsrA protein exhibited weak binding to 5’ luxS regulatory region. DNA protein interaction and chromatin immunoprecipitation analysis confirmed direct interaction of UvrY with the luxS promoter. Additionally, reduced expression of the fusion in hfq deletion mutant suggested involvement of small RNA interactions in luxS regulation. In contrast, the expression of lsrA operon involved in AI-2 uptake, is negatively regulated by uvrY and positively by csrA in a cell-density dependent manner. The dual role of csrA in AI-2 synthesis and uptake suggested a regulatory crosstalk of cell signaling with carbon regulation in Escherichia coli. We found that the cAMP-CRP mediated catabolite repression of luxS expression was uvrY dependent. This study suggests that luxS expression is complex and regulated at the level of transcription and translation. The multifactorial regulation supports the notion that cell-cell communication requires interaction and integration of multiple metabolic signals. PMID:27362507

  7. Large scale biosynthesis of ganglioside analogues by RERF-LC-AI cells cultured in HYPERFlask.

    PubMed

    Shimura, Yumiko; Suzuki, Junya; Muraoka, Miho; Kasuya, Maria Carmelita Zulueta; Matsuoka, Koji; Hatanaka, Kenichi

    2012-01-01

    The efficient production of ganglioside analogues was accomplished using RERF-LC-AI cells cultured in HYPERFlask (High Yield PERformance Flask). Eight kinds of ganglioside analogues (GM3, GM2, sialylparagloboside, GD3, di-sialylated lacto-N-tetraose, and another three kinds of analogues with intricate structures) were synthesized by the saccharide primer method using lung squamous-cell carcinoma line RERF-LC-AI and 12-azidododecyl β-lactoside primer. The yield for each analogue obtained using HYPERFlask was higher than yields obtained from 100-mm dishes.

  8. Inhibitory effect of açaí (Euterpe oleracea Mart.) pulp on IgE-mediated mast cell activation.

    PubMed

    Horiguchi, Tomoko; Ishiguro, Nahoko; Chihara, Kazuyasu; Ogi, Kazuhiro; Nakashima, Kenji; Sada, Kiyonao; Hori-Tamura, Naoko

    2011-05-25

    The palm fruit açaí is known to have potential health benefits due to its antioxidant scavenging capacities. Pretreatment of IgE-sensitized mouse primary cultured mast cells with açaí pulp resulted in the dramatic suppression of antigen-induced degranulation in a dose-dependent manner. Similarly, açaí suppressed IgE-mediated degranulation and transcription of the cytokine genes from a cultured mast cell line of rat basophilic leukemia (RBL)-2H3 cells. Açaí could selectively inhibit FcεRI signaling pathways. Furthermore, the FcεRI-mediated complementary signaling pathway was also suppressed by açaí. These results demonstrate that açaí is a potent inhibitor of IgE-mediated mast cell activation.

  9. Internet AIS

    NASA Astrophysics Data System (ADS)

    Filjar, Renato; Desic, Sasa; Pokrajac, Danijela; Cubic, Ivica

    2005-05-01

    Automatic Identification System (AIS) has recently become the leading issue in maritime navigation and traffic management worldwide. The present AIS solution, based on a VHF data communications scheme, provides AIS functionalities for SOLAS (AIS Class A) vessels only in a limited environment defined by radio propagation properties. Here we present a novel approach in AIS development based on current mobile communication technologies. It utilises existing mobile communications equipment that the majority of targetted end-users own and are familiar with. A novel AIS concept aims to offer a transition of AIS data traffic to mobile Internet. An innovative AIS architecture supports AIS data processing, storing and transferring to authorised parties. This enhances not only the operational area, but also provides the global AIS with data transfer security and an improved aids-for-navigation service, with all legally traceable vessels (both AIS Class A and AIS Class B) included in the system. In order to provide the development framework for Internet AIS, a set of essential four use-cases, a communication protocol and the first Internet AIS prototype have been recently developed and are briefly introduced in this article.

  10. Expression and purification of recombinant apolipoprotein A-I Zaragoza (L144R) and formation of reconstituted HDL particles.

    PubMed

    Fiddyment, Sarah; Barceló-Batllori, Sílvia; Pocoví, Miguel; García-Otín, Angel-Luis

    2011-11-01

    Apolipoprotein A-I Zaragoza (L144R) (apo A-I Z), has been associated with severe hypoalphalipoproteinemia and an enhanced effect of high density lipoprotein (HDL) reverse cholesterol transport. In order to perform further studies with this protein we have optimized an expression and purification method of recombinant wild-type apo A-I and apo A-I Z and produced mimetic HDL particles with each protein. An pET-45 expression system was used to produce N-terminal His-tagged apo A-I, wild-type or mutant, in Escherichia coli BL21 (DE3) which was subsequently purified by affinity chromatography in non-denaturing conditions. HDL particles were generated via a modified sodium cholate method. Expression and purification of both proteins was verified by SDS-PAGE, MALDI-TOF MS and immunochemical procedures. Yield was 30mg of purified protein (94% purity) per liter of culture. The reconstituted HDL particles checked via non-denaturing PAGE showed high homogeneity in their size when reconstituted both with wild-type apo A-I and apo A-I Z. An optimized system for the expression and purification of wild-type apo A-I and apo A-I Z with high yield and purity grade has been achieved, in addition to their use in reconstituted HDL particles, as a basis for further studies.

  11. Porosity formation in AI-9 Wt Pct Si-3 Wt Pct Cu alloy systems: Metallographic observations

    NASA Astrophysics Data System (ADS)

    Roy, N.; Samuel, A. M.; Samuel, F. H.

    1996-02-01

    The formation of porosity in Al-9 wt Pct Si-3 wt Pct Cu-X alloys was studied as a function of (1) the hydrogen content of the melt; (2) the melt treatment additives, namely, modifier (Sr), grain refiner (TiB2), and primary silicon refiner (P); (3) alloying elements for precipitation hardening such as Mg and Zn; (4) intermetallics (α-iron, β-iron, sludge, and Al2Cu); and (5) solidification conditions (so-lidification time and solidus velocity). The results were statistically analyzed, based on the quanti-tative image analysis data of the porosity observed in samples obtained from a set of 72 solidification experiments. Metallographic aspects of pore size and pore morphology related to the preceding parameters and the possible mechanisms of porosity formation are highlighted in this article. The results show that a melt hydrogen content of 0.1 mL/100 g Al has the same effect on percentage porosity as that obtained with an addition of 185 ppm strontium to the melt. Grain refiner particles, phosphorus, and magnesium reduce percentage porosity, although in different magnitudes. A Mg-Sr or Mg-GR combination further reduces the percentage porosity observed in the casting. The β needles of the Al5FeSi intermetallic phase are very active as pore nucleation sites. All intermetallics, viz. β needles, α-Chinese script phase, Al2Cu phase, and sludge restrict pore growth and expansion. In-creasing the local solidification time or the solidus velocity increases the pore parameters. Pore growth in the two cases is attributed, respectively, to a diffusion-controlled growth process and to the formation of hot spots.

  12. Structures Formation on the Y-TZP-AI2O3 Ceramic Composites Surface

    NASA Astrophysics Data System (ADS)

    Kulkov, Sergei; Sevostyanova, Irina; Sablina, Tatiana; Buyakova, Svetlana; Pshenichnyy, Artem; Savchenko, Nickolai

    2016-07-01

    The paper discusses the structure of Y-TZP-Al2O3 ceramics produced from nanopowders and friction surface, wear resistance, friction coefficient of Y-TZP-AEO3 composites rubbed against a steel disk counterface at a pressure of 5 MPa in a range of sliding speeds from 0.2 to 47 m/s. Analysis by X-ray diffraction, scanning electron microscopy showed that the high wear resistance of Y-TZP-Al2O3 composites at high sliding speeds is due to high-temperature phase transitions and protective film formation on the friction surface.

  13. Simvastatin, an HMG-CoA reductase inhibitor, induces the synthesis and secretion of apolipoprotein AI in HepG2 cells and primary hamster hepatocytes.

    PubMed

    Bonn, Victoria; Cheung, Raphael C; Chen, Biao; Taghibiglou, Changiz; Van Iderstine, Stephen C; Adeli, Khosrow

    2002-07-01

    Clinical studies have recently suggested that statin treatment may beneficially elevate plasma concentrations of high density lipoprotein (HDL)-cholesterol in patients with hyperlipidemia. Here, we have investigated the effect of a potent inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase on the synthesis and secretion of apolipoprotein AI (apoAI) in two model systems, HepG2 cells and primary hamster hepatocytes. Cultured cells were incubated with different doses of simvastatin (0.1-10 microM) for a period of 18 h. A dose-dependent increase in synthesis and secretion of apoAI was observed in both cell types. There was a significant increase in the synthesis of apoAI in HepG2 cells (44.3+/-12.1%), and hamster hepatocytes (212+/-2%) after treatment with 10 microM of the statin. The increase in apoAI synthesis appeared to result in a higher level of apoAI secreted into the culture media in both cell types (49.2+/-7.8% in HepG2, 197+/-0.2% in hamster hepatocytes). ApoAI mRNA levels were also significantly increased in both cell types in response to statin treatment. Control experiments with transferrin confirmed specificity of the effect on apoAI secretion. Analysis of a density fraction containing HDL particles in culture media revealed an increase in HDL-associated apoAI of 94.3+/-2.1% in HepG2 cells and 27.0+/-0.03% in hamster hepatocytes following 10 microM simvastatin-treatment. Comparative studies of simvastatin and lovastatin indicated a differential ability to induce apoAI synthesis and secretion, with simvastatin having a more significant effect. Thus, acute statin treatment of cultured hepatocytes (transformed as well as primary) resulted in a significant upregulation of apoAI mRNA and apoAI synthesis, causing oversecretion of apoAI and HDL extracellularly. The stimulatory effect on apoAI synthesis and secretion may thus explain the clinical observation of an elevated plasma HDL-cholesterol level in hyperlipidemic patients treated with

  14. Inhibition of apolipoprotein A-I gene expression by obesity-associated endocannabinoids.

    PubMed

    Haas, Michael J; Mazza, Angela D; Wong, Norman C W; Mooradian, Arshag D

    2012-04-01

    Obesity is associated with increased serum endocannabinoid (EC) levels and decreased high-density lipoprotein cholesterol (HDLc). Apolipoprotein A-I (apo A-I), the primary protein component of HDL is expressed primarily in the liver and small intestine. To determine whether ECs regulate apo A-I gene expression directly, the effect of the obesity-associated ECs anandamide and 2-arachidonylglycerol on apo A-I gene expression was examined in the hepatocyte cell line HepG2 and the intestinal cell line Caco-2. Apo A-I protein secretion was suppressed nearly 50% by anandamide and 2-arachidonoylglycerol in a dose-dependent manner in both cell lines. Anandamide treatment suppressed both apo A-I mRNA and apo A-I gene promoter activity in both cell lines. Studies using apo A-I promoter deletion constructs indicated that repression of apo A-I promoter activity by anandamide requires a previously identified nuclear receptor binding site designated as site A. Furthermore, anandamide-treatment inhibited protein-DNA complex formation with the site A probe. Exogenous over expression of cannabinoid receptor 1 (CBR1) in HepG2 cells suppressed apo A-I promoter activity, while in Caco-2 cells, exogenous expression of both CBR1 and CBR2 could repress apo A-I promoter activity. The suppressive effect of anandamide on apo A-I promoter activity in Hep G2 cells could be inhibited by CBR1 antagonist AM251 but not by AM630, a selective and potent CBR2 inhibitor. These results indicate that ECs directly suppress apo A-I gene expression in both hepatocytes and intestinal cells, contributing to the decrease in serum HDLc in obese individuals.

  15. Intraperitoneal injection (IP), Intravenous injection (IV) or anal injection (AI)? Best way for mesenchymal stem cells transplantation for colitis

    PubMed Central

    Wang, Min; Liang, Cong; Hu, Hao; Zhou, Lin; Xu, Bing; Wang, Xin; Han, Ying; Nie, Yongzhan; Jia, Shuyun; Liang, Jie; Wu, Kaichun

    2016-01-01

    Stem cell transplantation showed promising results in IBD management. However, the therapeutic impacts of cell delivery route that is critical for clinical translation are currently poorly understood. Here, three different MSCs delivery routes: intraperitoneal (IP), intravenous (IV), and anal injection (AI) were compared on DSS-induced colitic mice model. The overall therapeutic factors, MSCs migration and targeting as well as local immunomodulatory cytokines and FoxP3+ cells infiltration were analyzed. Colitis showed varying degrees of alleviation after three ways of MSCs transplantation, and the IP injection showed the highest survival rate of 87.5% and displayed the less weight loss and quick weight gain. The fecal occult blood test on the day 3 also showed nearly complete absence of occult blood in IP group. The fluorescence imaging disclosed higher intensity of engrafted cells in inflamed colon and the corresponding mesentery lymph nodes (MLNs) in IP and AI groups than the IV group. Real time-PCR and ELISA also demonstrate lower TNF-α and higher IL-10, TSG-6 levels in IP group. The immunohistochemistry indicated higher repair proliferation (Ki-67) and more FoxP3+ cells accumulation of IP group. IP showed better colitis recovery and might be the optimum MSCs delivery route for the treatment of DSS-induced colitis. PMID:27488951

  16. The role of apoproteins AI and AII in binding of high-density lipoprotein3 to membranes derived from bovine aortic endothelial cells.

    PubMed Central

    Vadiveloo, P K; Fidge, N H

    1992-01-01

    Although binding of high-density lipoproteins (HDL) to a variety of cells in culture has been widely reported, the mechanism of this binding has yet to be fully elucidated. The aim of the current studies was to explore the roles of apoproteins (apo) AI and AII in HDL3 binding to membranes derived from bovine aortic endothelial cells. Binding studies showed that HDL3 (which contains both apo AI and apo AII) and AII-HDL3 (which contain only apo AII) bound to membranes with similar affinity (44 +/- 6 and 41 +/- 9 micrograms/ml respectively) and capacity (673 +/- 97 and 969 +/- 101 ng bound/mg of membrane protein respectively). In contrast with these results, HDL3 [AI w/o AII] (which contain apo AI, but not apo AII) bound to the membranes with a significantly higher capacity (2228 +/- 206 ng bound/mg of membrane protein) and lower affinity (65 +/- 3 micrograms/ml) as compared with HDL3 or AII-HDL3. Therefore, although both apo AI and apo AII appear capable of facilitating HDL3 binding, the mechanisms involved probably differ. A model which fits the data postulates that a common receptor exists which binds both apo AI and apo AII, and that a particle containing AII can occupy up to four receptors (partly owing to each AII molecule containing two binding domains), whereas an HDL3 [AI w/o AII] particle can occupy only one. Images Fig. 3. PMID:1599393

  17. Anti-inflammatory activity of polyphenolics from açai (Euterpe oleracea Martius) in intestinal myofibroblasts CCD-18Co cells.

    PubMed

    Dias, Manoela Maciel dos Santos; Martino, Hércia Stampini Duarte; Noratto, Giuliana; Roque-Andrade, Andrea; Stringheta, Paulo César; Talcott, Stephen; Ramos, Afonso Mota; Mertens-Talcott, Susanne U

    2015-10-01

    The demand for tropical fruits high in polyphenolics including açai (Euterpe oleracea Mart.) has been increasing based on ascribed health benefits and antioxidant properties. This study evaluated the anti-inflammatory activities of açai polyphenolics in human colon myofibroblastic CCD-18Co cells to investigate the suppression of reactive oxygen species (ROS), and mRNA and protein expression of inflammatory proteins. Non-cytotoxic concentrations of açai extract, 1-5 mg gallic acid equivalent L(-1), were selected. The generation of ROS was induced by lipopolysaccharide (LPS) and açai extract partially reversed this effect to 0.53-fold of the LPS-control. Açai extract (5 mg GAE L(-1)) down-regulated LPS-induced mRNA-expression of tumor necrosis factor alpha, TNF-α (to 0.42-fold), cyclooxygenase 2, COX-2 (to 0.61-fold), toll-like receptor-4, TLR-4 (to 0.52-fold), TNF receptor-associated factor 6, TRAF-6 (to 0.64-fold), nuclear factor kappa-B, NF-κB (to 0.76-fold), vascular cell adhesion molecule 1, VCAM-1 (to 0.71-fold) and intercellular adhesion molecule 1, ICAM-1 (to 0.68-fold). The protein levels of COX-2, TLR-4, p-NF-κB and ICAM-1 were induced by LPS and the açai extract partially reversed this effect in a dose-dependent manner. These results suggest the anti-inflammatory effect of açai polyphenolic extract in intestinal cells are at least in part mediated through the inhibition of ROS and the expression of TLR-4 and NF-κB. Results indicate the potential for açai polyphenolics in the prevention of intestinal inflammation.

  18. Recent progresses on AI-2 bacterial quorum sensing inhibitors.

    PubMed

    Zhu, Peng; Li, Minyong

    2012-01-01

    Quorum sensing (QS) is a communication procedure that predominates gene expression in response to cell density and fluctuations in the neighboring environment as a result of discerning molecules termed autoinducers (AIs). It has been embroiled that QS can govern bacterial behaviors such as the secretion of virulence factors, biofilm formation, bioluminescence production, conjugation, sporulation and swarming motility. Autoinducer 2 (AI-2), a QS signaling molecule brought up to be involved in interspecies communication, exists in both gram-negative and -positive bacteria. Therefore, novel approaches to interrupt AI-2 quorum sensing are being recognized as next generation antimicrobials. In the present review article, we summarized recent progresses on AI-2 bacterial quorum sensing inhibitors and discussed their potential as the antibacterial agents.

  19. Pro-apoptotic activities of polyphenolics from açai (Euterpe oleracea Martius) in human SW-480 colon cancer cells.

    PubMed

    Dias, Manoela Maciel dos Santos; Noratto, Giuliana; Martino, Hercia Stampini Duarte; Arbizu, Shirley; Peluzio, Maria do Carmo Gouveia; Talcott, Stephen; Ramos, Afonso Mota; Mertens-Talcott, Susanne U

    2014-01-01

    This study aimed to evaluate the cell growth inhibition activity of açai (Euterpe oleracea Mart.) polyphenolic extract against colon cancer HT-29 and SW-480 cells and the nonmalignant CCD-18Co colon fibroblast cells. Results showed that açai polyphenolic extract (5-20 mg/L) inhibited preferentially the growth of SW-480 cells with no toxicity in CCD-18Co cells, and this was accompanied by reduction of H2O2-induced reactive oxygen species (ROS) generation. The mechanisms involved in SW-480 cell growth-inhibition by açai polyphenolic extract included the downregulation of NF-κB proinflammatory transcription factor and the nuclear factor-kappa B targets intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Furthermore, prooncogenic specificity proteins (Sp) were downregulated as well as Sp-targets Bcl-2, vascular endothelial growth factor, and survivin. This was accompanied by activation of mitochondrial proapoptotic pathway involving increase of cytochrome c, cleavage of caspase-3, and decrease of PARP-1. Results strongly suggest that açai polyphenolic extract has antiinflammatory and cytotoxic activities in colon cancer cells and can be effective as natural colon cancer chemopreventive agents.

  20. Interactions between lipid-free apolipoprotein-AI and a lipopeptide incorporating the RGDS cell adhesion motif

    NASA Astrophysics Data System (ADS)

    Castelletto, V.; Hamley, I. W.; Reza, M.; Ruokolainen, J.

    2014-11-01

    The interaction of a designed bioactive lipopeptide C16-GGGRGDS, comprising a hexadecyl lipid chain attached to a functional heptapeptide, with the lipid-free apoliprotein, Apo-AI, is examined. This apolipoprotein is a major component of high density lipoprotein and it is involved in lipid metabolism and may serve as a biomarker for cardiovascular disease and Alzheimers' disease. We find via isothermal titration calorimetry that binding between the lipopeptide and Apo-AI occurs up to a saturation condition, just above equimolar for a 10.7 μM concentration of Apo-AI. A similar value is obtained from circular dichroism spectroscopy, which probes the reduction in α-helical secondary structure of Apo-AI upon addition of C16-GGGRGDS. Electron microscopy images show a persistence of fibrillar structures due to self-assembly of C16-GGGRGDS in mixtures with Apo-AI above the saturation binding condition. A small fraction of spheroidal or possibly ``nanodisc'' structures was observed. Small-angle X-ray scattering (SAXS) data for Apo-AI can be fitted using a published crystal structure of the Apo-AI dimer. The SAXS data for the lipopeptide/Apo-AI mixtures above the saturation binding conditions can be fitted to the contribution from fibrillar structures coexisting with flat discs corresponding to Apo-AI/lipopeptide aggregates.

  1. D-4F, an apolipoprotein A-I mimetic, inhibits TGF-β1 induced epithelial-mesenchymal transition in human alveolar epithelial cell.

    PubMed

    You, Jia; Wang, Jintao; Xie, Linshen; Zhu, Chengwen; Xiong, Jingyuan

    2016-10-01

    Emerging evidences support that transforming growth factor β1 (TGF-β1) induced epithelial-mesenchymal transition (EMT) participates in the pathogenesis of pulmonary fibrosis and asthmatic airway remodeling. Recent studies demonstrated that apolipoprotein A-I (Apo A-I) is the only known substance that can resolve established pulmonary fibrotic nodules, and Apo A-I mimetic D-4F (a synthetic polypeptide consisting of 18 amino acids) plays an inhibitory role in murine asthmatic model. However, cellular mechanisms for such therapeutic effects of Apo A-I and D-4F remain to be elucidated. This study evaluated the effects of D-4F on TGF-β1 induced EMT in human type II alveolar epithelial cell line A549. A549 cells treated with 10ng/ml of TGF-β1 manifested distinct EMT, including fibroblastic morphological changes, down-regulation of epithelial marker E-cadherin and up-regulation of mesenchymal marker vimentin. These EMT related changes were all inhibited by D-4F in a concentration dependent manner. Transcriptional investigation demonstrated clearly that D-4F dose-dependently compensated for the reduced E-cadherin mRNA level and the increased vimentin mRNA level in TGF-β1 treated A549 cells. Translational analysis revealed that D-4F significantly reversed the TGF-β1 induced changes of E-cadherin and vimentin levels. These results suggested that D-4F inhibits TGF-β1 induced EMT in human alveolar epithelial cell. Given the functional similarities between D-4F and Apo A-I, it is speculated that D-4F and Apo A-I are able to exert possible anti-fibrotic and anti-asthmatic effects via inhibiting alveolar EMT, and D-4F may possess beneficial clinical potential for patients suffering from pulmonary fibrosis and asthma.

  2. Detection of autoinducer (AI-2)-like activity in food samples.

    PubMed

    Sivakumar, Kirthiram K; Jesudhasan, Palmy R; Pillai, Suresh D

    2011-01-01

    The contamination, survival, and possible foodborne disease outbreaks are major issues confronting the food industry. However, from a microbial perspective, any food whether natural or processed is just another environmental niche that is available for colonization. Quorum sensing or cell-cell communication is a process by which microorganisms are thought to communicate with each other using a variety of small molecules termed autoinducers. The autoinducer AI-2 is thought to be a universal signaling molecule due to its ability to modulate the gene expression of a number of different bacterial species and genera. Pathogens such as Pseudomonas aeruginosa, Aeromonas hydrophila, Vibrio anguillarum, Streptococcus sp., and Burkholderia cepacia form biofilms on a variety of man-made and natural surfaces using cell-cell mechanisms. It is important to detect and study autoinducers and their activities in foods, since a better understanding of these molecules in food and food ingredients may help in designing new approaches to thwart microbial persistence and biofilm formation. The autoinducer AI-2 is thought to be involved in microbial attachment and biofilm formation leading to food spoilage. To better understand microbial cell-cell signaling in foods especially as it relates to pathogen persistence, biofilm formation, and food spoilage, methods to process, extract, and purify autoinducer molecules need to be developed. This chapter details methods to process food samples to obtain cell-free supernatants (CFS), which could subsequently be tested for the presence of AI-2 or "AI-2-like activity" in the extracted CFS using autoinducer bioassays. Additionally, the method of synthesizing AI-2 in the laboratory is also provided. The methods that are presented in this chapter are based on previously published research articles from the authors' laboratory.

  3. Anthocyanin-rich açai (Euterpe oleracea Mart.) fruit pulp fractions attenuate inflammatory stress signaling in mouse brain BV-2 microglial cells.

    PubMed

    Poulose, Shibu M; Fisher, Derek R; Larson, Jessica; Bielinski, Donna F; Rimando, Agnes M; Carey, Amanda N; Schauss, Alexander G; Shukitt-Hale, Barbara

    2012-02-01

    Age-related diseases of the brain compromise memory, learning, and movement and are directly linked with increases in oxidative stress and inflammation. Previous research has shown that supplementation with berries can modulate signaling in primary hippocampal neurons or BV-2 mouse microglial cells. Because of their high polyphenolic content, fruit pulp fractions of açai ( Euterpe oleracea Mart.) were explored for their protective effect on BV-2 mouse microglial cells. Freeze-dried açai pulp was fractionated using solvents with different polarities and analyzed using HPLC for major anthocyanins and other phenolics. Fractions extracted using methanol (MEOH) and ethanol (ETOH) were particularly rich in anthocyanins such as cyanidin, delphinidin, malvidin, pelargonidin, and peonidin, whereas the fraction extracted using acetone (ACE) was rich in other phenolics such as catechin, ferulic acid, quercetin, resveratrol, and synergic and vanillic acids. Studies were conducted to investigate the mitigating effects of açai pulp extracts on lipopolysaccharide (LPS, 100 ng/mL) induced oxidative stress and inflammation; treatment of BV-2 cells with acai fractions resulted in significant (p < 0.05) decreases in nitrite production, accompanied by a reduction in inducible nitric oxide synthase (iNOS) expression. The inhibition pattern was emulated with the ferulic acid content among the fractions. The protection of microglial cells by açai pulp extracts, particularly that of MEOH, ETOH, and ACE fractions, was also accompanied by a significant concentration-dependent reduction in cyclooxygenase-2 (COX-2), p38 mitogen-activated protein kinase (p38-MAPK), tumor necrosis factor-α (TNFα), and nuclear factor κB (NF-κB). The current study offers valuable insights into the protective effects of açai pulp fractions on brain cells, which could have implications for improved cognitive and motor functions.

  4. Apolipoprotein A-I modulates regulatory T cells in autoimmune LDLr-/-, ApoA-I-/- mice.

    PubMed

    Wilhelm, Ashley J; Zabalawi, Manal; Owen, John S; Shah, Dharika; Grayson, Jason M; Major, Amy S; Bhat, Shaila; Gibbs, Dwayne P; Thomas, Michael J; Sorci-Thomas, Mary G

    2010-11-12

    The immune system is complex, with multiple layers of regulation that serve to prevent the production of self-antigens. One layer of regulation involves regulatory T cells (Tregs) that play an essential role in maintaining peripheral self-tolerance. Patients with autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis have decreased levels of HDL, suggesting that apoA-I concentrations may be important in preventing autoimmunity and the loss of self-tolerance. In published studies, hypercholesterolemic mice lacking HDL apoA-I or LDLr(-/-), apoA-I(-/-) (DKO), exhibit characteristics of autoimmunity in response to an atherogenic diet. This phenotype is characterized by enlarged cholesterol-enriched lymph nodes (LNs), as well as increased T cell activation, proliferation, and the production of autoantibodies in plasma. In this study, we investigated whether treatment of mice with lipid-free apoA-I could attenuate the autoimmune phenotype. To do this, DKO mice were first fed an atherogenic diet containing 0.1% cholesterol, 10% fat for 6 weeks, after which treatment with apoA-I was begun. Subcutaneous injections of 500 μg of lipid-free apoA-I was administered every 48 h during the treatment phase. These and control mice were maintained for an additional 6 weeks on the diet. At the end of the 12-week study, DKO mice showed decreased numbers of LN immune cells, whereas Tregs were proportionately increased. Accompanying this increase in Tregs was a decrease in the percentage of effector/effector memory T cells. Furthermore, lipid accumulation in LN and skin was reduced. These results suggest that treatment with apoA-I reduces inflammation in DKO mice by augmenting the effectiveness of the LN Treg response.

  5. Effect of lipid-bound apolipoprotein A-I cysteine mutant on ATF3 in RAW264.7 cells

    PubMed Central

    Wang, Yunlong; Wang, Yanhui; Jia, Shaoyou; Dong, Qingzhe; Chen, Yuanbin

    2017-01-01

    Activating transcription factor 3 (ATF3) is a TLR-induced repressor that plays an important role in the inhibition of specific inflammatory signals. We previously constructed recombinant high density lipoproteins (rHDL) (including rHDLWT, rHDLM, rHDL228 and rHDL74) and found that rHDL74 had a strong anti-inflammatory ability. In the present study, we investigate the roles of recombinant apolipoprotein A-I (ApoA-I) (rHDLWT) and its cysteine mutant HDLs (rHDLM, rHDL228 and rHDL74) on ATF3 function in RAW264.7 cells stimulated by lipopolysaccharide. Our results showed that compared with the LPS group, rHDL74 can decrease the level of TNF-α and IL-6, whereas rHDL228 increases their expression levels. RT-PCR and Western blotting results showed that compared with the LPS group, rHDL74, rHDLWT and rHDLM can markedly increase the expression level of ATF3, whereas the level of ATF3 decreases in the rHDL228 group. In summary, the different anti-inflammatory mechanisms of the ApoA-I cysteine mutants might be associated with the regulation of ATF3 level. PMID:28093456

  6. Decreased apolipoprotein A-I level indicates poor prognosis in extranodal natural killer/T-cell lymphoma, nasal type

    PubMed Central

    Quan, Qi; Chen, Qi; Chen, Ping; Jiang, Li; Li, Tingwei; Qiu, Huijuan; Zhang, Bei

    2016-01-01

    Background Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTL) is an invasive lymphoid malignancy with unfavorable survival, for which a prognostic model has not yet been validated. We hypothesized that serum apolipoprotein A-I (ApoA-I) may serve as a novel prognostic marker for ENKTL. Patients and methods A total of 236 newly diagnosed cases of ENKTL were analyzed retrospectively. Results The optimal cutoff value for the serum ApoA-I level was determined to be 0.95 g/L. A total of 154 and 82 cases were assigned to the high and low ApoA-I groups, respectively. Patients in the low ApoA-I group tended to present with poorer clinical features, a lower complete remission rate (P=0.001), and poor median progression-free survival (P<0.001) and overall survival (P<0.001). Multivariate analysis using Cox model showed that the serum ApoA-I level was an independent prognostic marker of overall survival (P<0.001) and progression-free survival (P<0.001) for ENKTL patients. For cases in the low-risk group, as assessed by International Prognostic Index, Prognosis Index for peripheral T-cell lymphoma, unspecified, and Korean Prognostic Index, the serum ApoA-I level was able to differentiate cases with poor outcomes from cases with good outcomes. Conclusion Our results showed that the baseline serum ApoA-I level was helpful for predicting ENKTL prognosis. PMID:27051293

  7. Apolipoprotein A-I configuration and cell cholesterol efflux activity of discoidal lipoproteins depend on the reconstitution process.

    PubMed

    Cuellar, Luz Ángela; Prieto, Eduardo Daniel; Cabaleiro, Laura Virginia; Garda, Horacio Alberto

    2014-01-01

    Discoidal high-density lipoproteins (D-HDL) are critical intermediates in reverse cholesterol transport. Most of the present knowledge of D-HDL is based on studies with reconstituted lipoprotein complexes of apolipoprotein A-I (apoA-I) obtained by cholate dialysis (CD). D-HDL can also be generated by the direct microsolubilization (DM) of phospholipid vesicles at the gel/fluid phase transition temperature, a process mechanistically similar to the "in vivo" apoAI lipidation via ABCA1. We compared the apoA-I configuration in D-HDL reconstituted with dimyristoylphosphatidylcholine by both procedures using fluorescence resonance energy transfer measurements with apoA-I tryptophan mutants and fluorescently labeled cysteine mutants. Results indicate that apoA-I configuration in D-HDL depends on the reconstitution process and are consistent with a "double belt" molecular arrangement with different helix registry. As reported by others, a configuration with juxtaposition of helices 5 of each apoAI monomer (5/5 registry) predominates in D-HDL obtained by CD. However, a configuration with helix 5 of one monomer juxtaposed with helix 2 of the other (5/2 registry) would predominate in D-HDL generated by DM. Moreover, we also show that the kinetics of cholesterol efflux from macrophage cultures depends on the reconstitution process, suggesting that apoAI configuration is important for this HDL function.

  8. Artificial Intelligence Study (AIS).

    DTIC Science & Technology

    1987-02-01

    ARTIFICIAL INTELLIGNECE HARDWARE ....... 2-50 AI Architecture ................................... 2-49 AI Hardware ....................................... 2...Epstein (1986) has suggested that this version of PROLOG has been used for business and industrial applications in Eastern Europe. The Japanese have...have been in building expert systems in the business analysis area. Expert systems for policy and rate selection for insurance (i.e., risk analysis) and

  9. T'ai Chi

    MedlinePlus

    ... you start your first t'ai chi workout, dress comfortably so you can move and stretch easily. ... health problem. Is your schedule jam-packed with school, work, and social activities? Here are a few ...

  10. T'ai Chi

    MedlinePlus

    ... chi (pronounced: TY CHEE) is great for improving flexibility and strengthening your legs, abs, and arms. What ... general, though, practicing t'ai chi improves strength, flexibility, and respiratory function (breathing). So where can you ...

  11. Autophagosome formation in mammalian cells.

    PubMed

    Burman, Chloe; Ktistakis, Nicholas T

    2010-12-01

    Autophagy is a fundamental intracellular trafficking pathway conserved from yeast to mammals. It is generally thought to play a pro-survival role, and it can be up regulated in response to both external and intracellular factors, including amino acid starvation, growth factor withdrawal, low cellular energy levels, endoplasmic reticulum (ER) stress, hypoxia, oxidative stress, pathogen infection, and organelle damage. During autophagy initiation a portion of the cytosol is surrounded by a flat membrane sheet known as the isolation membrane or phagophore. The isolation membrane then elongates and seals itself to form an autophagosome. The autophagosome fuses with normal endocytic traffic to mature into a late autophagosome, before fusing with lysosomes. The molecular machinery that enables formation of an autophagosome in response to the various autophagy stimuli is almost completely identified in yeast and-thanks to the observed conservation-is also being rapidly elucidated in higher eukaryotes including mammals. What are less clear and currently under intense investigation are the mechanism by which these various autophagy components co-ordinate in order to generate autophagosomes. In this review, we will discuss briefly the fundamental importance of autophagy in various pathophysiological states and we will then review in detail the various players in early autophagy. Our main thesis will be that a conserved group of heteromeric protein complexes and a relatively simple signalling lipid are responsible for the formation of autophagosomes in mammalian cells.

  12. AI aerospace components

    NASA Technical Reports Server (NTRS)

    Heindel, Troy A.; Murphy, Terri B.; Rasmussen, Arthur N.; Mcfarland, Robert Z.; Montgomery, Ronnie E.; Pohle, George E.; Heard, Astrid E.; Atkinson, David J.; Wedlake, William E.; Anderson, John M.

    1991-01-01

    An evaluation is made of the application of novel, AI-capabilities-related technologies to aerospace systems. Attention is given to expert-system shells for Space Shuttle Orbiter mission control, manpower and processing cost reductions at the NASA Kennedy Space Center's 'firing rooms' for liftoff monitoring, the automation of planetary exploration systems such as semiautonomous mobile robots, and AI for battlefield staff-related functions.

  13. Fatty acid modulation of autoinducer (AI-2) influenced growth and macrophage invasion by Salmonella Typhimurium.

    PubMed

    Widmer, Kenneth W; Jesudhasan, Palmy; Pillai, Suresh D

    2012-03-01

    Autoinducer-2 (AI-2) is a small molecule that is involved in bacterial cell-to-cell signaling whose precursor formation is mediated by luxS. A luxS mutant of Salmonella Typhimurium PJ002 (ΔluxS) was grown in glucose-containing M-9 minimal medium supplemented with varying concentrations (1×, 10×, and 100×) of long-chain fatty acids (linoleic acid, oleic acid, palmitic acid, and stearic acid) to study the influence of fatty acids on growth rate and macrophage invasion. Additionally, in vitro synthesized AI-2 was added to this medium to identify the influence of AI-2 on S. Typhimurium PJ002 (ΔluxS) growth rate and macrophage invasion. The growth rate constant (k) for each experimental treatment was determined based on OD₆₀₀ values recorded during 12 h of incubation. There was a significant (p=0.01) increase in the growth rate of S. Typhimurium PJ002 (ΔluxS) in the presence of AI-2 when compared to the phosphate-buffered saline (PBS) control. However, fatty acids either singly or in a mixture were unable to influence AI-2's effect on growth rate. The presence of AI-2 significantly (p=0.02) decreased the invasiveness of S. Typhimurium PJ002 (ΔluxS) towards the murine macrophage cell line, RAW 264.7. However, the fatty acid mixture was able to reverse this reduction and restore invasiveness to background levels. These results suggest that, while AI-2 may enhance the growth rate and reduce macrophage invasion by the luxS mutant S. Typhimurium PJ002 (ΔluxS), fatty acids may influence the virulence in S. Typhimurium (PJ002) by modulating AI-2 activity.

  14. A First Look at Airborne Imaging Spectrometer (AIS) Data in an Area of Altered Volcanic Rocks and Carbonate Formations, Hot Creek Range, South Central Nevada

    NASA Technical Reports Server (NTRS)

    Feldman, S. C.; Taranik, J. V.; Mouat, D. A.

    1985-01-01

    Three flight lines of Airborne Imaging Spectrometer (AIS) data were collected in 128 bands between 1.2 and 2.4 microns in the Hot Creek Range, Nevada on July 25, 1984. The flight lines are underlain by hydrothermally altered and unaltered Paleozoic carbonates and Tertiary rhyolitic to latitic volcanics in the Tybo mining district. The original project objectives were to discriminate carbonate rocks from other rock types, to distinguish limestone from dolomite, and to discriminate carbonate units from each other using AIS imagery. Because of high cloud cover over the prime carbonate flight line and because of the acquisition of another flight line in altered and unaltered volcanics, the study has been extended to the discrimination of alteration products. In an area of altered and unaltered rhyolites and latites in Red Rock Canyon, altered and unaltered rock could be discriminated from each other using spectral features in the 1.16 to 2.34 micron range. The altered spectral signatures resembled montmorillonite and kaolinite. Field samples were gathered and the presence of montmorillonite was confirmed by X-ray analysis.

  15. AI in manufacturing

    NASA Technical Reports Server (NTRS)

    Gross, John E.; Minato, Rick; Smith, David M.; Loftin, R. B.; Savely, Robert T.

    1991-01-01

    AI techniques are shown to have been useful in such aerospace industry tasks as vehicle configuration layouts, process planning, tool design, numerically-controlled programming of tools, production scheduling, and equipment testing and diagnosis. Accounts are given of illustrative experiences at the production facilities of three major aerospace defense contractors. Also discussed is NASA's autonomous Intelligent Computer-Aided Training System, for such ambitious manned programs as Space Station Freedom, which employs five different modules to constitute its job-independent training architecture.

  16. Phenol induced acute cutaneous inflammation (AI) in mice: Diminished response in mast cell-deficient (W/W sup v ) mice and evidence of a role for tumor necrosis factor-alpha (TNF)

    SciTech Connect

    Wershil, B.K.; Wang, Z.S.; Gordon, J.R.; Galli, S.J. Harvard Medical School, Boston, MA )

    1991-03-11

    AI can be induced by a variety of chemical agents. The authors examined AI in mast cell-deficient (WBB6F{sub 1}-W/W{sup v}) and congenic normal (WBB6F{sub 1}-+/+) mice; AI was induced by the epicutaneous application to the ear of phenol (2 mg), benzalkonium chloride (BC; 1 mg) and ethyl phenylpropiolate (EPP, 2 or 5 mg). Phenol induced significantly greater swelling in +/+ than in W/W{sup v} mice. No difference in swelling was seen in +/+ versus W/W{sup v} mice with BC or EEP. Phenol application induced significantly greater neutrophil infiltration in +/+ than in W/W{sup v} mice. Mast cells represent a rich source of TNF and TNF has been shown to participate in the neutrophil accumulation seen in mast cell-dependent, IgE-mediated cutaneous late phase reactions. The authors injected +/+ mice i.d. with 20 {mu}l of 1:100 dilution of a polyclonal rabbit anti-mouse TNF antiserum or 20 {mu}l of medium and then applied 2 mg phenol at the same sites. At 24 hrs, significantly less neutrophil accumulation was seen in the ear treated with anti-TNF antibodies than in the control ear. The authors conclude that mast cells may participate in phenol-induced AI, and that TNF contributes to this response.

  17. Direct formate fuel cells: A review

    NASA Astrophysics Data System (ADS)

    An, L.; Chen, R.

    2016-07-01

    Direct formate fuel cells (DFFC), which convert the chemical energy stored in formate directly into electricity, are recently attracting more attention, primarily because of the use of the carbon-neutral fuel and the low-cost electrocatalytic and membrane materials. As an emerging energy technology, the DFFC has made a rapid progress in recent years (currently, the state-of-the-art power density is 591 mW cm-2 at 60 °C). This article provides a review of past research on the development of this type of fuel cell, including the working principle, mechanisms and materials of the electrocatalytic oxidation of formate, singe-cell designs and performance, as well as innovative system designs. In addition, future perspectives with regard to the development of this fuel cell system are also highlighted.

  18. Heparin and Methionine Oxidation Promote the Formation of Apolipoprotein A-I Amyloid Comprising α-Helical and β-Sheet Structures.

    PubMed

    Townsend, David; Hughes, Eleri; Hussain, Rohanah; Siligardi, Giuliano; Baldock, Sarah; Madine, Jillian; Middleton, David A

    2017-03-13

    Peptides derived from apolipoprotein A-I (apoA-I), the main component of high-density lipoprotein (HDL), constitute the main component of amyloid deposits that colocalize with atherosclerotic plaques. Here we investigate the molecular details of full-length, lipid-deprived apoA-I after assembly into insoluble aggregates under physiologically relevant conditions known to induce aggregation in vitro. Unmodified apoA-I is shown to remain soluble at pH 7 for at least 3 days, retaining its native α-helical-rich structure. Upon acidification to pH 4, apoA-I rapidly assembles into insoluble nonfibrillar aggregates lacking the characteristic cross-β features of amyloid. In the presence of heparin, the rate and thioflavin T responsiveness of the aggregates formed at pH 4 increase and short amyloid-like fibrils are observed, which give rise to amyloid-characteristic X-ray reflections at 4.7 and 10 Å. Solid-state nuclear magnetic resonance (SSNMR) and synchrotron radiation circular dichroism spectroscopy of fibrils formed in the presence of heparin show they retain some α-helical characteristics together with new β-sheet structures. Interestingly, SSNMR indicates a similar molecular structure of aggregates formed in the absence of heparin at pH 6 after oxidation of the three methionine residues, although their morphology is rather different from that of the heparin-derived fibrils. We propose a model for apoA-I aggregation in which perturbations of a four-helix bundle-like structure, induced by interactions of heparin or methionine oxidation, cause the partially helical N-terminal residues to disengage from the remaining, intact helices, thereby allowing self-assembly via β-strand associations.

  19. Differential spheroid formation by oral cancer cells.

    PubMed

    Lee, Carlin; Lee, Casey; Atakilit, Amha; Siu, Amanda; Ramos, Daniel M

    2014-12-01

    Squamous cell carcinomas (SCC) make up 96% of all oral cancers. Most laboratory SCC studies grow cells as a monolayer, which does not accurately represent the disease in vivo. We used a more relevant multicellular spheroid (MCS) model to study this disease. The SCC9β6KDFyn cell line, which expresses full-length β6 and a kinase dead Fyn formed the largest MCS. Cell adhesive properties are dynamic and N-cadherin was increased in the largest MCS. c-Raf mediates the survival of tumor cells and was consistently expressed both in monolayers and in the MCS by SCC9β6D1 cells which lack the β6 cytoplasmic tail and, do not activate Fyn. SCC9β6KDFyn cells also express high levels of c-Raf when grown as spheroids in which Fyn suppression stimulates MCS formation. Tumor microenvironment and growth patterns modulate cell behavior and suppression of Fyn kinase may promote MCS growth.

  20. Mast cells mediate malignant pleural effusion formation

    PubMed Central

    Giannou, Anastasios D.; Marazioti, Antonia; Spella, Magda; Kanellakis, Nikolaos I.; Apostolopoulou, Hara; Psallidas, Ioannis; Prijovich, Zeljko M.; Vreka, Malamati; Zazara, Dimitra E.; Lilis, Ioannis; Papaleonidopoulos, Vassilios; Kairi, Chrysoula A.; Patmanidi, Alexandra L.; Giopanou, Ioanna; Spiropoulou, Nikolitsa; Harokopos, Vaggelis; Aidinis, Vassilis; Spyratos, Dionisios; Teliousi, Stamatia; Papadaki, Helen; Taraviras, Stavros; Snyder, Linda A.; Eickelberg, Oliver; Kardamakis, Dimitrios; Iwakura, Yoichiro; Feyerabend, Thorsten B.; Rodewald, Hans-Reimer; Kalomenidis, Ioannis; Blackwell, Timothy S.; Agalioti, Theodora; Stathopoulos, Georgios T.

    2015-01-01

    Mast cells (MCs) have been identified in various tumors; however, the role of these cells in tumorigenesis remains controversial. Here, we quantified MCs in human and murine malignant pleural effusions (MPEs) and evaluated the fate and function of these cells in MPE development. Evaluation of murine MPE-competent lung and colon adenocarcinomas revealed that these tumors actively attract and subsequently degranulate MCs in the pleural space by elaborating CCL2 and osteopontin. MCs were required for effusion development, as MPEs did not form in mice lacking MCs, and pleural infusion of MCs with MPE-incompetent cells promoted MPE formation. Once homed to the pleural space, MCs released tryptase AB1 and IL-1β, which in turn induced pleural vasculature leakiness and triggered NF-κB activation in pleural tumor cells, thereby fostering pleural fluid accumulation and tumor growth. Evaluation of human effusions revealed that MCs are elevated in MPEs compared with benign effusions. Moreover, MC abundance correlated with MPE formation in a human cancer cell–induced effusion model. Treatment of mice with the c-KIT inhibitor imatinib mesylate limited effusion precipitation by mouse and human adenocarcinoma cells. Together, the results of this study indicate that MCs are required for MPE formation and suggest that MC-dependent effusion formation is therapeutically addressable. PMID:25915587

  1. A complete backbone spectral assignment of human apolipoprotein AI on a 38 kDa preβHDL (Lp1-AI) particle

    SciTech Connect

    Ren, Xuefeng; Yang, Yunhuang; Neville, T.; Hoyt, David W.; Sparks, Daniel L.; Wang, Jianjun

    2007-06-12

    Apolipoprotein A-I (apoAI, 243-residues) is the major protein component of the high-density lipoprotein (HDL) that has been a hot subject of interests because of its anti-atherogenic properties. This important property of apoAI is related to its roles in reverse cholesterol transport pathway. Upon lipid-binding, apoAI undergoes conformational changes from lipid-free to several different HDL-associated states (1). These different conformational states regulate HDL formation, maturation and transportation. Two initial conformational states of apoAI are lipid-free apoAI and apoAI/preβHDL that recruit phospholipids and cholesterol to form HDL particles. In particular, lipid-free apoAI specifically binds to phospholipids to form lipid-poor apoAI, including apoAI/preβ-HDL (~37 kDa). As a unique class of lipid poor HDL, both in vitro and in vivo evidence demonstrates that apoAI/preβ-HDLs are the most effective acceptors specifically for free cholesterol in human plasma and serves as the precursor of HDL particles (2). Here we report a complete backbone spectral assignment of human apoAI/preβHDL. Secondary structure prediction using backbone NMR parameters indicates that apoAI/preβHDL displays a two-domain structure: the N-terminal four helix-bundle domain (residues 1-186) and the C-terminal flexible domain (residues 187-243). A structure of apoAI/preβ-HDL is the first lipid-associated structure of apoAI and is critical for us to understand how apoAI recruits cholesterol to initialize HDL formation. BMRB deposit with accession number: 15093.

  2. Associative memory cells: Formation, function and perspective

    PubMed Central

    Wang, Jin-Hui; Cui, Shan

    2017-01-01

    Associative learning and memory are common activities in life, and their cellular infrastructures constitute the basis of cognitive processes. Although neuronal plasticity emerges after memory formation, basic units and their working principles for the storage and retrieval of associated signals remain to be revealed. Current reports indicate that associative memory cells, through their mutual synapse innervations among the co-activated sensory cortices, are recruited to fulfill the integration, storage and retrieval of multiple associated signals, and serve associative thinking and logical reasoning. In this review, we aim to summarize associative memory cells in their formation, features and functional impacts.

  3. Contribution of Vascular Cells to Neointimal Formation

    PubMed Central

    Yuan, Falei; Wang, Dong; Xu, Kang; Wang, Jixian; Zhang, Zhijun; Yang, Li; Yang, Guo-Yuan; Li, Song

    2017-01-01

    The de-differentiation and proliferation of smooth muscle cells (SMCs) are widely accepted as the major contributor to vascular remodeling. However, recent studies indicate that vascular stem cells (VSCs) also play an important role, but their relative contribution remains to be elucidated. In this study, we used genetic lineage tracing approach to further investigate the contribution of SMCs and VSCs to neointimal thickening in response to endothelium denudation injury or artery ligation. In vitro and in vivo analysis of MYH11-cre/Rosa-loxP-RFP mouse artery showed that SMCs proliferated at a much slower rate than non-SMCs. Upon denudation or ligation injury, two distinct types of neointima were identified: Type-I neointimal cells mainly involved SMCs, while Type II mainly involved non-SMCs. Using Sox10-cre/Rosa-loxP-LacZ mice, we found that Sox10+ cells were one of the cell sources in neointima. In addition, lineage tracing using Tie2-cre/Rosa-LoxP-RFP showed that endothelial cells also contributed to the neointimal formation, but rarely transdifferentiated into mesenchymal lineages. These results provide a novel insight into the contribution of vascular cells to neointima formation, and have significant impact on the development of more effective therapies that target specific vascular cell types. PMID:28060852

  4. Cell lipid metabolism modulators 2-bromopalmitate, D609, monensin, U18666A and probucol shift discoidal HDL formation to the smaller-sized particles: implications for the mechanism of HDL assembly.

    PubMed

    Quach, Duyen; Vitali, Cecilia; La, Fiona M; Xiao, Angel X; Millar, John S; Tang, Chongren; Rader, Daniel J; Phillips, Michael C; Lyssenko, Nicholas N

    2016-12-01

    ATP-binding cassette transporter A1 (ABCA1) mediates formation of disc-shaped high-density lipoprotein (HDL) from cell lipid and lipid-free apolipoprotein A-I (apo A-I). Discoidal HDL particles are heterogeneous in physicochemical characteristics for reasons that are understood incompletely. Discoidal lipoprotein particles similar in characteristics and heterogeneity to cell-formed discoidal HDL can be reconstituted from purified lipids and apo A-I by cell-free, physicochemical methods. The heterogeneity of reconstituted HDL (rHDL) is sensitive to the lipid composition of the starting lipid/apo A-I mixture. To determine whether the heterogeneity of cell-formed HDL is similarly sensitive to changes in cell lipids, we investigated four compounds that have well-established effects on cell lipid metabolism and ABCA1-mediated cell cholesterol efflux. 2-Bromopalmitate, D609, monensin and U18666A decreased formation of the larger-sized, but dramatically increased formation of the smaller-sized HDL. 2-Bromopalmitate did not appear to affect ABCA1 activity, subcellular localization or oligomerization, but induced dissolution of the cholesterol-phospholipid complexes in the plasma membrane. Arachidonic and linoleic acids shifted HDL formation to the smaller-sized species. Tangier disease mutations and inhibitors of ABCA1 activity wheat germ agglutinin and AG 490 reduced formation of both larger-sized and smaller-sized HDL. The effect of probucol was similar to the effect of 2-bromopalmitate. Taking rHDL formation as a paradigm, we propose that ABCA1 mutations and activity inhibitors reduce the amount of cell lipid available for HDL formation, and the compounds in the 2-bromopalmitate group and the polyunsaturated fatty acids change cell lipid composition from one that favors formation of the larger-sized HDL particles to one that favors formation of the smaller-sized species.

  5. Continuum Theory of Dislocations: Cell Structure Formation

    NASA Astrophysics Data System (ADS)

    Limkumnerd, Surachate; Sethna, James P.

    2005-03-01

    Line-like topological defects inside metals are called dislocations. These dislocations in late stages of hardening form patterns called cell structures. We are developing a mesoscale theory for the formation of cell structures that systematically derives the order parameter fields and evolution laws from the conserved topological Burgers vector density or the Nye dislocation tensor. (In classical plasticity theories, describing scales large compared to these cells, one normally bypasses the complicated motions of the dislocations by supplying yield surface and plastic hardening function in order to determine the evolution of state variables.) Using Landau approach and a closure approximation, an evolution equation for the dislocation density tensor is obtained by employing simple symmetry arguments and the constraint that the elastic energy must decrease with time at fixed stress. The evolution laws lead to singularity formation at finite times, which we expect will be related to the formation of cell walls. Implementation of finite difference simulations using the upwind scheme and the results in one and higher dimensions will be discussed.

  6. Black knight of AI

    SciTech Connect

    Rose, F.

    1985-03-01

    For two decades now, Hubert Dreyfus, an existentialist philosopher at the University of California at Berkeley, has been in the forefront of the controversy over artificial intelligence. He maintains that computers will never be able to think because scientists will never come up with a suitably rigorous set of rules to describe how we think. To many computer scientists, this is like saying the Earth is flat. But so far, none of them have been able to prove him wrong. Even most AI researchers now admit that before they can make computers any smarter, they'll have to come up with an explanation of how intelligence works in people. This realization has coincided with the emergence of cognitive science, a new discipline linking philosophy, psychology, anthroplogy, linguistics, neuroscience, and computer science in an attempt to develop a theory of the way humans think. The guiding principle of most cognitive science research is the notion that the mind, like the computer, is a system for manipulating symbols - for processing information. The task of cognitive science is to discover how this processing occurs.

  7. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2015-07-21

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  8. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2014-07-22

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline materiat layer; and forming conductive contacts in the plurality of contact holes.

  9. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David; Cousins, Peter

    2012-12-04

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  10. Processing the Interspecies Quorum-sensing Signal Autoinducer-2 (AI-2)

    SciTech Connect

    J Marques; P Lamosa; C Russell; R Ventura; C Maycock; M Semmelhack; S Miller; K Xavier

    2011-12-31

    The molecule (S)-4,5-dihydroxy-2,3-pentanedione (DPD) is produced by many different species of bacteria and is the precursor of the signal molecule autoinducer-2 (AI-2). AI-2 mediates interspecies communication and facilitates regulation of bacterial behaviors such as biofilm formation and virulence. A variety of bacterial species have the ability to sequester and process the AI-2 present in their environment, thereby interfering with the cell-cell communication of other bacteria. This process involves the AI-2-regulated lsr operon, comprised of the Lsr transport system that facilitates uptake of the signal, a kinase that phosphorylates the signal to phospho-DPD (P-DPD), and enzymes (like LsrG) that are responsible for processing the phosphorylated signal. Because P-DPD is the intracellular inducer of the lsr operon, enzymes involved in P-DPD processing impact the levels of Lsr expression. Here we show that LsrG catalyzes isomerization of P-DPD into 3,4,4-trihydroxy-2-pentanone-5-phosphate. We present the crystal structure of LsrG, identify potential catalytic residues, and determine which of these residues affects P-DPD processing in vivo and in vitro. We also show that an lsrG deletion mutant accumulates at least 10 times more P-DPD than wild type cells. Consistent with this result, we find that the lsrG mutant has increased expression of the lsr operon and an altered profile of AI-2 accumulation and removal. Understanding of the biochemical mechanisms employed by bacteria to quench signaling of other species can be of great utility in the development of therapies to control bacterial behavior.

  11. Processing the Interspecies Quorum-sensing Signal Autoinducer-2 (AI-2)

    PubMed Central

    Marques, João C.; Lamosa, Pedro; Russell, Caitlin; Ventura, Rita; Maycock, Christopher; Semmelhack, Martin F.; Miller, Stephen T.; Xavier, Karina B.

    2011-01-01

    The molecule (S)-4,5-dihydroxy-2,3-pentanedione (DPD) is produced by many different species of bacteria and is the precursor of the signal molecule autoinducer-2 (AI-2). AI-2 mediates interspecies communication and facilitates regulation of bacterial behaviors such as biofilm formation and virulence. A variety of bacterial species have the ability to sequester and process the AI-2 present in their environment, thereby interfering with the cell-cell communication of other bacteria. This process involves the AI-2-regulated lsr operon, comprised of the Lsr transport system that facilitates uptake of the signal, a kinase that phosphorylates the signal to phospho-DPD (P-DPD), and enzymes (like LsrG) that are responsible for processing the phosphorylated signal. Because P-DPD is the intracellular inducer of the lsr operon, enzymes involved in P-DPD processing impact the levels of Lsr expression. Here we show that LsrG catalyzes isomerization of P-DPD into 3,4,4-trihydroxy-2-pentanone-5-phosphate. We present the crystal structure of LsrG, identify potential catalytic residues, and determine which of these residues affects P-DPD processing in vivo and in vitro. We also show that an lsrG deletion mutant accumulates at least 10 times more P-DPD than wild type cells. Consistent with this result, we find that the lsrG mutant has increased expression of the lsr operon and an altered profile of AI-2 accumulation and removal. Understanding of the biochemical mechanisms employed by bacteria to quench signaling of other species can be of great utility in the development of therapies to control bacterial behavior. PMID:21454635

  12. Typical and atypical AIS. Pathogenesis.

    PubMed

    Dudin, M; Pinchuk, D

    2012-01-01

    AIS hypothesis has the right to recognition, if it explains the transition of "healthy" vertebra column into status of "scoliotic" one. AIS is the most investigated disease in the history of orthopedics, but up the present time there is no clear explanation of some its phenomena: vertebra column mono-form deformation along with its poly etiology character, interrelation of its origin and development and child's growth process etc. The key for authors' view at AIS was scoliosis with non-standard (concave side) rotation. On the bases of its' multifunctional instrumental investigation results (Rtg, EMG, EEG, optical topography, hormonal and neuropeptides trials, thermo-vision methods and other) in comparison with typical AIS was worked out the new hypothesis, part of it is suggested for discussion. In the work under observation is the sequence of appearance of typical and atypical scoliosis symptomatology beginning from the preclinical stage.

  13. Code AI Personal Web Pages

    NASA Technical Reports Server (NTRS)

    Garcia, Joseph A.; Smith, Charles A. (Technical Monitor)

    1998-01-01

    The document consists of a publicly available web site (george.arc.nasa.gov) for Joseph A. Garcia's personal web pages in the AI division. Only general information will be posted and no technical material. All the information is unclassified.

  14. AIS ASM Operational Integration Plan

    DTIC Science & Technology

    2013-08-01

    River , WA; and the future Vessel Traffic Service systems being developed under PAWSS. Interfacing the AIS Transmit architecture with agencies that...provides accurate real-time information such as water levels, currents, and other oceanographic and meteorological data. The USACE provide river lock...information and river level and current data on the Inland Waterways. AIS ASM Operational Integration Plan viii UNCLAS//Public | CG-926 R&DC

  15. Pattern formation in cell membrane adhesion

    NASA Astrophysics Data System (ADS)

    Discher, Dennis; Hategan, A.; Sengupta, K.; Sackmann, E.

    2004-03-01

    Strong adhesion of highly active cells often nucleates focal adhesions or related structures that are, over time, reinforced by cytoskeleton (actin, etc.). Red cells lack such complex adhesion systems, but they are shown here to also exhibit complex spatial patterns within an adhesive contact zone. While strong adhesion and spreading of the red cell to a dense poly-L-lysine surface appears complete in < 1 s by reflective interference microscopy, over longer times of 10-15 min or more distinct patterns in fluorescently labeled membrane components emerge. The fluorescent lipid Fl-PE (fluorescein phosphoethanolamine), in particular, is seen to diffuse and reorganize (eg. worm-like domains of <500 nm) within the contact zone, independent of whether the cell is intact or ruptured. Lipid patterns are accompanied by visible perturbations in band 3 distribution and weaker perturbations in membrane skeleton actin. Although fluorescent poly-L-lysine is shown to be uniform under cells, pressing down on the membrane quenches the lipid patterns and reveals the topographical basis for pattern formation. Regions of strong contact are thus separated by regions where the membrane is more distant from the surface.

  16. Isoliensinine induces dephosphorylation of NF-κB p65 subunit at Ser536 via a PP2A-dependent mechanism in hepatocellular carcinoma cells: roles of impairing PP2A/I2PP2A interaction

    PubMed Central

    Shu, Guangwen; Zhang, Lang; Jiang, Shanqing; Cheng, Zhuo; Wang, Guan; Huang, Xu; Yang, Xinzhou

    2016-01-01

    Our previous study discovered that isoliensinine (isolie) triggers hepatocellular carcinoma (HCC) cell apoptosis via inducing p65 dephosphorylation at Ser536 and inhibition of NF-κB. Here, we showed that isolie promoted p65/PP2A interaction in vitro and in vivo. Repression of PP2A activity or knockdown of the expression of PP2A-C (the catalytic subunit of PP2A) abrogated isolie-provoked p65 dephosphorylation. I2PP2A is an endogenous PP2A inhibitor. Isolie directly impaired PP2A/I2PP2A interaction. Knockdown of I2PP2A boosted p65/PP2A association and p65 dephosphorylation. Overexpression of I2PP2A restrained isolie-induced p65 dephosphorylation. Untransformed hepatocytes were insensitive to isolie-induced NF-κB inhibition and cell apoptosis. In these cells, basal levels of I2PP2A and p65 phosphorylation at Ser536 were lower than in HCC cells. These findings collectively indicated that isolie suppresses NF-κB in HCC cells through impairing PP2A/I2PP2A interaction and stimulating PP2A-dependent p65 dephosphorylation at Ser536. PMID:27244888

  17. Isoliensinine induces dephosphorylation of NF-kB p65 subunit at Ser536 via a PP2A-dependent mechanism in hepatocellular carcinoma cells: roles of impairing PP2A/I2PP2A interaction.

    PubMed

    Shu, Guangwen; Zhang, Lang; Jiang, Shanqing; Cheng, Zhuo; Wang, Guan; Huang, Xu; Yang, Xinzhou

    2016-06-28

    Our previous study discovered that isoliensinine (isolie) triggers hepatocellular carcinoma (HCC) cell apoptosis via inducing p65 dephosphorylation at Ser536 and inhibition of NF-κB. Here, we showed that isolie promoted p65/PP2A interaction in vitro and in vivo. Repression of PP2A activity or knockdown of the expression of PP2A-C (the catalytic subunit of PP2A) abrogated isolie-provoked p65 dephosphorylation. I2PP2A is an endogenous PP2A inhibitor. Isolie directly impaired PP2A/I2PP2A interaction. Knockdown of I2PP2A boosted p65/PP2A association and p65 dephosphorylation. Overexpression of I2PP2A restrained isolie-induced p65 dephosphorylation. Untransformed hepatocytes were insensitive to isolie-induced NF-κB inhibition and cell apoptosis. In these cells, basal levels of I2PP2A and p65 phosphorylation at Ser536 were lower than in HCC cells. These findings collectively indicated that isolie suppresses NF-κB in HCC cells through impairing PP2A/I2PP2A interaction and stimulating PP2A-dependent p65 dephosphorylation at Ser536.

  18. Novel solar cells in a wire format.

    PubMed

    Chen, Tao; Qiu, Longbin; Yang, Zhibin; Peng, Huisheng

    2013-06-21

    Photovoltaic devices in a wire format have recently attracted increasing attention as, compared with the conventional planar structure, they show unique and promising advantages. For instance, they are light-weight and can be easily woven into clothes or integrated into other structures, which enable applications in electronic textiles and various complex devices. In this tutorial review, the recent advancement in photovoltaic wires including both dye-sensitized and polymer solar cells are described. Two main architectures based on a single core-sheath fiber and twisted fibers are carefully illustrated with an emphasis on the comparison of various substrates which have been focused in past development. The current challenge including low energy conversion efficiency and low stability and future direction of the wire-shaped cell have been finally summarized.

  19. Organic Tandem Solar Cells: Design and Formation

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Chao

    polyelectrolyte layer functioning as the surface dipole formation layer to provide better electrical contact with the photoactive layer. Due to the effectiveness of the conjugated polyelectrolyte layer, performance improvement was also observed. Furthermore, other issues regarding the semi-transparent tandem solar cells (e.g., photocurrent matching, exterior color tuning, and transparency tuning) are all explored to optimize best performance. In Chapter 5 and 6, the architectures of double- and triple-junction tandem solar cells are explored. Theoretically, triple-junction tandem solar cells with three photoactive absorbers with cascaded energy bandgaps have the potential to achieve higher performance, in comparison with double-junction tandem solar cells. Such expectations can be ascribed to the minimized carrier thermalization loss and further improved light absorption. However, the design of triple-junction solar cells often involves sophisticated multiple layer deposition as well as substantial optimization. Therefore, there is a lack of successful demonstrations of triple-junction solar cells outperforming the double-junction counterparts. To solve the incompatible issues related to the layer deposition in the fabrication, we proposed a novel architecture of inverted-structure tandem solar cells with newly designed interconnecting layers. Our design of interconnecting layers does not only focus on maintaining the orthogonal solution processing advantages, but also provides an excellent compatibility in the energy level alignment to allow different absorber materials to be used. Furthermore, we also explored the light management inside the double- and triple-junction tandem solar cells. The study of light management was carried out through optical simulation method based transfer matrix formalism. The intention is to obtain a balanced photocurrent output from each subcells inside the tandem solar cell, thus the minimal recombination loss at the contact of interconnecting

  20. Formative cell divisions: principal determinants of plant morphogenesis.

    PubMed

    Smolarkiewicz, Michalina; Dhonukshe, Pankaj

    2013-03-01

    Formative cell divisions utilizing precise rotations of cell division planes generate and spatially place asymmetric daughters to produce different cell layers. Therefore, by shaping tissues and organs, formative cell divisions dictate multicellular morphogenesis. In animal formative cell divisions, the orientation of the mitotic spindle and cell division planes relies on intrinsic and extrinsic cortical polarity cues. Plants lack known key players from animals, and cell division planes are determined prior to the mitotic spindle stage. Therefore, it appears that plants have evolved specialized mechanisms to execute formative cell divisions. Despite their profound influence on plant architecture, molecular players and cellular mechanisms regulating formative divisions in plants are not well understood. This is because formative cell divisions in plants have been difficult to track owing to their submerged positions and imprecise timings of occurrence. However, by identifying a spatiotemporally inducible cell division plane switch system applicable for advanced microscopy techniques, recent studies have begun to uncover molecular modules and mechanisms for formative cell divisions. The identified molecular modules comprise developmentally triggered transcriptional cascades feeding onto microtubule regulators that now allow dissection of the hierarchy of the events at better spatiotemporal resolutions. Here, we survey the current advances in understanding of formative cell divisions in plants in the context of embryogenesis, stem cell functionality and post-embryonic organ formation.

  1. Contact formation in gallium arsenide solar cells

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1988-01-01

    Gold and gold-based alloys, commonly used as solar cell contact materials, are known to react readily with gallium arsenide. Experiments were performed to identify the mechanisms involved in these GaAs-metal interactions. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are explained by invoking this mechanism.

  2. CASCADE: Introducing AI into CBT.

    ERIC Educational Resources Information Center

    Hendley, R. J.; Jurascheck, N.

    1992-01-01

    Discusses changes in training requirements of commerce and industry in the United Kingdom and describes a project, CASCADE, that was developed to investigate and implement the introduction of artificial intelligence (AI) techniques into computer-based training (CBT). An overview of pilot projects in higher education settings is provided. (eight…

  3. AIS Investigation of Agricultural Monocultures

    NASA Technical Reports Server (NTRS)

    Wood, B. L.; Wrigley, R. C.

    1985-01-01

    Airborne Imaging Spectrometer (AIS) data were acquired over an agricultural area in eastern San Joaquin County, California in July, 1984. Cover type information was subsequently collected for all fields along this flight line. The lack of detailed ground data on individual fields, however, limited AIS data analysis to a qualitative comparison of the spectral reflectance curves for a total of nine cover types. Based on this analysis, it appears that cover types with a positive slope in the 1550 to 1700 nm region have a higher spectral response in the 1200 to 1300 nm region compared to those cover types with a negative slope in the 1550 to 1700 nm region. Within cover type, spectral variability was also found to be greater than that between cover types. Given the lack of additional field data, the reason for these differences is a matter of speculation.

  4. Autoinducer AI-2 is involved in regulating a variety of cellular processes in Salmonella Typhimurium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    LuxS/AI-2 mediated cell signaling is a known strategy that modulates a variety of bacterial processes in prokaryotes. Salmonella Typhimurium is known to possess LuxS/AI-2 mediated cell signaling. Until now, the Lsr- ABC transporter system (LuxS- regulated) is the only known process controlled by t...

  5. Macrophage apoAI protects against dyslipidemia-induced dermatitis and atherosclerosis without affecting HDL.

    PubMed

    Tavori, Hagai; Su, Yan Ru; Yancey, Patricia G; Giunzioni, Ilaria; Wilhelm, Ashley J; Blakemore, John L; Zabalawi, Manal; Linton, MacRae F; Sorci-Thomas, Mary G; Fazio, Sergio

    2015-03-01

    Tissue cholesterol accumulation, macrophage infiltration, and inflammation are features of atherosclerosis and some forms of dermatitis. HDL and its main protein, apoAI, are acceptors of excess cholesterol from macrophages; this process inhibits tissue inflammation. Recent epidemiologic and clinical trial evidence questions the role of HDL and its manipulation in cardiovascular disease. We investigated the effect of ectopic macrophage apoAI expression on atherosclerosis and dermatitis induced by the combination of hypercholesterolemia and absence of HDL in mice. Hematopoietic progenitor cells were transduced to express human apoAI and transplanted into lethally irradiated LDL receptor(-/-)/apoAI(-/-) mice, which were then placed on a high-fat diet for 16 weeks. Macrophage apoAI expression reduced aortic CD4(+) T-cell levels (-39.8%), lesion size (-25%), and necrotic core area (-31.6%), without affecting serum HDL or aortic macrophage levels. Macrophage apoAI reduced skin cholesterol by 39.8%, restored skin morphology, and reduced skin CD4(+) T-cell levels. Macrophage apoAI also reduced CD4(+) T-cell levels (-32.9%) in skin-draining lymph nodes but had no effect on other T cells, B cells, dendritic cells, or macrophages compared with control transplanted mice. Thus, macrophage apoAI expression protects against atherosclerosis and dermatitis by reducing cholesterol accumulation and regulating CD4(+) T-cell levels, without affecting serum HDL or tissue macrophage levels.

  6. Formal verification of AI software

    NASA Technical Reports Server (NTRS)

    Rushby, John; Whitehurst, R. Alan

    1989-01-01

    The application of formal verification techniques to Artificial Intelligence (AI) software, particularly expert systems, is investigated. Constraint satisfaction and model inversion are identified as two formal specification paradigms for different classes of expert systems. A formal definition of consistency is developed, and the notion of approximate semantics is introduced. Examples are given of how these ideas can be applied in both declarative and imperative forms.

  7. Macrophage colony-stimulating factor gene transduction into human lung cancer cells differentially regulates metastasis formations in various organ microenvironments of natural killer cell-depleted SCID mice.

    PubMed

    Yano, S; Nishioka, Y; Nokihara, H; Sone, S

    1997-02-15

    We investigated whether local production of macrophage colony-stimulating factor (M-CSF), responsible for migration and activation of monocytes/macrophages at a tumor growth site, affected the metastatic pattern of lung cancer. For this, highly metastatic human squamous (RERF-LC-AI) or small (H69/VP) cell lung carcinoma cells were transduced with the human M-CSF gene inserted into pRc/CMV-MCSF to establish M-CSF-producing clones (MCSF-AI-9-18, MCSF-AI-9-24, and MCSF-VP-5). M-CSF gene transduction had no effect on the expression of surface antigen or on in vitro proliferation. After s.c. injection into SCID mice, the growth rates of M-CSF-producing cells were slower than those of parent or mock-transduced cells. In the metastatic model in SCID mice depleted of natural killer cells, RERF-LC-AI cells formed metastases mainly in the liver and kidneys, whereas H69/VP cells metastasized mainly to the liver and systemic lymph nodes. The numbers of metastatic colonies of MCSF-AI-9-18 and MCSF-AI-9-24 cells in the liver but not the kidneys were significantly reduced. The development of lymph node metastases of MCSF-VP-5 cells was also less than that of parent or mock-transduced cells. Treatment of SCID mice with anti-human M-CSF antibody resulted in a significant increase in liver metastases of their M-CSF gene transfectants. No significant differences were observed in the distributions in mice or in the in vitro invasive potentials of MCSF-AI-9-18 cells and Neo-AI-3 cells. These findings indicate that the antimetastatic effect of M-CSF may be specific to particular organs, suggesting the influence of heterogeneity of organ microenvironments on the metastasis of lung cancer.

  8. Formation of multilayer aggregates of mammalian cells by dielectrophoresis

    NASA Astrophysics Data System (ADS)

    Sebastian, Anil; Buckle, Anne-Marie; Markx, Gerard H.

    2006-09-01

    The formation of aggregates of mammalian cells at interdigitated oppositely castellated electrodes by positive dielectrophoresis was investigated. It is shown that, by using a constant small flow of fresh sorbitol iso-osmotic buffer through the chamber to remove ions leaking from the cells, a high positive DEP force can be maintained throughout the formation of the aggregates. Flow-rate dependent optima were found in the aggregate height as a function of the electrode size. It is shown that at low flow rates the creation of aggregates of mammalian cells with heights over 150 µm is feasible using relatively low voltages (20 Vpk-pk, 1 MHz). The formation of layered aggregates of two specialized cell types—stromal cells and Jurkat T lymphocytes—is demonstrated. The work confirms that dielectrophoresis can be reliably used for the formation of aggregates with three-dimensional architectures, which could be used as artificial microniches for the study of interactions between cells.

  9. Induction of the apolipoprotein AI gene by fasting: a relationship with ketosis but not with ketone bodies.

    PubMed

    Haas, M J; Reinacher, D; Pun, K; Wong, N C; Mooradian, A D

    2000-12-01

    Apolipoprotein AI (apoAI) expression is inversely related to the incidence of atherosclerosis. ApoAI expression is also influenced by the nutritional state and diabetes. We used both cell culture and animal models to examine the effect of fasting and ketoacidosis on apoAI gene expression. Two days of food deprivation in rats increased hepatic and intestinal apoAI mRNA by 2.6- and 2.3-fold, respectively (P < .05). The absolute concentration of plasma apoAI did not change. However, the plasma apoAI concentration relative to the plasma concentration of serum proteins was increased 23% (P < .05). In fasting rats, there was a significant positive correlation between the serum beta-hydroxybutyrate concentration and hepatic or intestinal apoAI mRNA level. Despite this correlation, changes in apoAI mRNA are probably not mediated by ketone bodies, since neither hepatic nor intestinal apoAI mRNA levels were altered in rats maintained on a ketogenic diet for 10 days or treated with isobutyramide, an orally active ketone analog. In addition, the activity of the rat apoAI promoter was not altered in Hep G2 cells treated with isobutyramide or fatty acids or exposed to hypoglycemic conditions, while dexamethasone increased promoter activity 1.9-fold (P < .05). These data indicate that metabolic changes other than ketone bodies, such as an increase in plasma glucocorticoids, may account for starvation-induced expression of apoAI.

  10. Formation and cultivation of medaka primordial germ cells.

    PubMed

    Li, Zhendong; Li, Mingyou; Hong, Ni; Yi, Meisheng; Hong, Yunhan

    2014-07-01

    Primordial germ cell (PGC) formation is pivotal for fertility. Mammalian PGCs are epigenetically induced without the need for maternal factors and can also be derived in culture from pluripotent stem cells. In egg-laying animals such as Drosophila and zebrafish, PGCs are specified by maternal germ plasm factors without the need for inducing factors. In these organisms, PGC formation and cultivation in vitro from indeterminate embryonic cells have not been possible. Here, we report PGC formation and cultivation in vitro from blastomeres dissociated from midblastula embryos (MBEs) of the fish medaka (Oryzias latipes). PGCs were identified by using germ-cell-specific green fluorescent protein (GFP) expression from a transgene under the control of the vasa promoter. Embryo perturbation was exploited to study PGC formation in vivo, and dissociated MBE cells were cultivated under various conditions to study PGC formation in vitro. Perturbation of somatic development did not prevent PGC formation in live embryos. Dissociated MBE blastomeres formed PGCs in the absence of normal somatic structures and of known inducing factors. Most importantly, under culture conditions conducive to stem cell derivation, some dissociated MBE blastomeres produced GFP-positive PGC-like cells. These GFP-positive cells contained genuine PGCs, as they expressed PGC markers and migrated into the embryonic gonad to generate germline chimeras. Our data thus provide evidence for PGC preformation in medaka and demonstrate, for the first time, that PGC formation and derivation can be obtained in culture from early embryos of medaka as a lower vertebrate model.

  11. Closure of supporting cell scar formations requires dynamic actin mechanisms

    PubMed Central

    Hordichok, Andrew J.; Steyger, Peter S.

    2007-01-01

    In many vertebrate inner ear sensory epithelia, dying sensory hair cells are extruded, and the apices of surrounding supporting cells converge to re-seal the epithelial barrier between the electrochemically-distinct endolymph and perilymph. These cellular mechanisms remain poorly understood. Dynamic microtubular mechanisms have been proposed for hair cell extrusion; while contractile actomyosin-based mechanisms are required for cellular extrusion and closure in epithelial monolayers. The hypothesis that cytoskeletal mechanisms are required for hair cell extrusion and supporting cell scar formation was tested using bullfrog saccules incubated with gentamicin (6 hours), and allowed to recover (18 hours). Explants were then fixed, labeled for actin and cytokeratins, and viewed with confocal microscopy. To block dynamic cytoskeletal processes, disruption agents for microtubules (colchicine, paclitaxel) myosin (Y-27632, ML-9) or actin (cytochalasin D, latrunculin A) were added during treatment and recovery. Microtubule disruption agents had no effect on hair cell extrusion or supporting cell scar formation. Myosin disruption agents appeared to slow down scar formation but not hair cell extrusion. Actin disruption agents blocked scar formation, and largely prevented hair cell extrusion. These data suggest that actin-based cytoskeletal processes are required for hair cell extrusion and supporting cell scar formation in bullfrog saccules. PMID:17716843

  12. Sucrose-mediated giant cell formation in the genus Neisseria.

    PubMed

    Johnson, K G; McDonald, I J

    1976-03-01

    Growth of Neisseria perflava, Neisseria cinerea, and Neisseria sicca strain Kirkland in media supplemented with sucrose (0.5 to 5.0% w/v) resulted in the formation of giant cells. Response to sucrose was specific in that a variety of other carbohydrates did not mediate giant cell formation. Giant cells appeared only under growth conditions and did not lyse upon transfer to medium lacking sucrose or upon resuspension in hypotonic media. Reversion of giant to normal cells occurred when giant cells were used as inocula and allowed to multiply in media lacking sucrose.

  13. Mapping AIS coverage for trusted surveillance

    NASA Astrophysics Data System (ADS)

    Lapinski, Anna-Liesa S.; Isenor, Anthony W.

    2010-10-01

    Automatic Identification System (AIS) is an unattended vessel reporting system developed for collision avoidance. Shipboard AIS equipment automatically broadcasts vessel positional data at regular intervals. The real-time position and identity data from a vessel is received by other vessels in the area thereby assisting with local navigation. As well, AIS broadcasts are beneficial to those concerned with coastal and harbour security. Land-based AIS receiving stations can also collect the AIS broadcasts. However, reception at the land station is dependent upon the ship's position relative to the receiving station. For AIS to be used as a trusted surveillance system, the characteristics of the AIS coverage area in the vicinity of the station (or stations) should be understood. This paper presents some results of a method being investigated at DRDC Atlantic, Canada) to map the AIS coverage characteristics of a dynamic AIS reception network. The method is shown to clearly distinguish AIS reception edges from those edges caused by vessel traffic patterns. The method can also be used to identify temporal changes in the coverage area, an important characteristic for local maritime security surveillance activities. Future research using the coverage estimate technique is also proposed to support surveillance activities.

  14. A Kinetic Model for Cell Damage Caused by Oligomer Formation.

    PubMed

    Hong, Liu; Huang, Ya-Jing; Yong, Wen-An

    2015-10-06

    It is well known that the formation of amyloid fiber may cause invertible damage to cells, although the underlying mechanism has not been fully understood. In this article, a microscopic model considering the detailed processes of amyloid formation and cell damage is constructed based on four simple assumptions, one of which is that cell damage is raised by oligomers rather than mature fibrils. By taking the maximum entropy principle, this microscopic model in the form of infinite mass-action equations together with two reaction-convection partial differential equations (PDEs) has been greatly coarse-grained into a macroscopic system consisting of only five ordinary differential equations (ODEs). With this simple model, the effects of primary nucleation, elongation, fragmentation, and protein and seeds concentration on amyloid formation and cell damage have been extensively explored and compared with experiments. We hope that our results will provide new insights into the quantitative linkage between amyloid formation and cell damage.

  15. USACE AIS Transmit Technical Support Summary Report

    DTIC Science & Technology

    2014-09-01

    USACE AIS Transmit Technical Support Summary Report Distribution Statement A: Approved for public release; distribution is unlimited...September 2014 Report No. CD-D-09-15 USACE AIS Transmit Technical Support Summary Report ii UNCLAS//Public | CG-926 RDC | I. Gonin et al. Public...States Coast Guard Research & Development Center 1 Chelsea Street New London, CT 06320 USACE AIS Transmit Technical Support Summary Report

  16. Membrane tether formation from blebbing cells.

    PubMed Central

    Dai, J; Sheetz, M P

    1999-01-01

    Membrane tension has been proposed to be important in regulating cell functions such as endocytosis and cell motility. The apparent membrane tension has been calculated from tether forces measured with laser tweezers. Both membrane-cytoskeleton adhesion and membrane tension contribute to the tether force. Separation of the plasma membrane from the cytoskeleton occurs in membrane blebs, which could remove the membrane-cytoskeleton adhesion term. In renal epithelial cells, tether forces are significantly lower on blebs than on membranes that are supported by cytoskeleton. Furthermore, the tether forces are equal on apical and basolateral blebs. In contrast, tether forces from membranes supported by the cytoskeleton are greater in apical than in basolateral regions, which is consistent with the greater apparent cytoskeletal density in the apical region. We suggest that the tether force on blebs primarily contains only the membrane tension term and that the membrane tension may be uniform over the cell surface. Additional support for this hypothesis comes from observations of melanoma cells that spontaneously bleb. In melanoma cells, tether forces on blebs are proportional to the radius of the bleb, and as large blebs form, there are spikes in the tether force in other cell regions. We suggest that an internal osmotic pressure inflates the blebs, and the pressure calculated from the Law of Laplace is similar to independent measurements of intracellular pressures. When the membrane tension term is subtracted from the apparent membrane tension over the cytoskeleton, the membrane-cytoskeleton adhesion term can be estimated. In both cell systems, membrane-cytoskeleton adhesion was the major factor in generating the tether force. PMID:10585959

  17. Foam cell formation by particulate matter (PM) exposure: a review.

    PubMed

    Cao, Yi; Long, Jimin; Ji, Yuejia; Chen, Gui; Shen, Yuexin; Gong, Yu; Li, Juan

    2016-11-01

    Increasing evidence suggests that exposure of particulate matter (PM) from traffic vehicles, e.g., diesel exhaust particles (DEP), was associated with adverse vascular effects, e.g., acceleration of atherosclerotic plaque progression. By analogy, engineered nanoparticles (NPs) could also induce similar effects. The formation of lipid laden foam cells, derived predominately from macrophages and vascular smooth muscle cells (VSMC), is closely associated with the development of atherosclerosis and adverse vascular effects. We reviewed current studies about particle exposure-induced lipid laden foam cell formation. In vivo studies using animal models have shown that exposure of air pollution by PM promoted lipid accumulation in alveolar macrophages or foam cells in plaques, which was likely associated with pulmonary inflammation or systemic oxidative stress, but not blood lipid profile. In support of these findings, in vitro studies showed that direct exposure of cultured macrophages to DEP or NP exposure, with or without further exposure to external lipids, promoted intracellular lipid accumulation. The mechanisms remained unknown. Although a number studies found increased reactive oxygen species (ROS) or an adaptive response to oxidative stress, the exact role of oxidative stress in mediating particle-induced foam cell formation requires future research. There is currently lack of reports concerning VSMC as a source for foam cells induced by particle exposure. In the future, it is necessary to explore the role of foam cell formation in particle exposure-induced atherosclerosis development. In addition, the formation of VSMC derived foam cells by particle exposure may also need extensive studies.

  18. Chloride influx provokes lamellipodium formation in microglial cells.

    PubMed

    Zierler, Susanna; Frei, Eva; Grissmer, Stephan; Kerschbaum, Hubert H

    2008-01-01

    Lamellipodium extension and retraction is the driving force for cell migration. Although several studies document that activation of chloride channels are essential in cell migration, little is known about their contribution in lamellipodium formation. To address this question, we characterized chloride channels and transporters by whole cell recording and RT-PCR, respectively, as well as quantified lamellipodium formation in murine primary microglial cells as well as the microglial cell-line, BV-2, using time-lapse microscopy. The repertoire of chloride conducting pathways in BV-2 cells included, swelling-activated chloride channels as well as the KCl cotransporters, KCC1, KCC2, KCC3, and KCC4. Swelling-activated chloride channels were either activated by a hypoosmotic solution or by a high KCl saline, which promotes K(+) and Cl(-) influx instead of efflux by KCCs. Conductance through swelling-activated chloride channels was completely blocked by flufenamic acid (200 microM), SITS (1 mM) and DIOA (10 microM). By exposing primary microglial cells or BV-2 cells to a high KCl saline, we observed a local swelling, which developed into a prominent lamellipodium. Blockade of chloride influx by flufenamic acid (200 microM) or DIOA (10 microM) as well as incubation of cells in a chloride-free high K(+) saline suppressed formation of a lamellipodium. We assume that local swellings, established by an increase in chloride influx, are a general principle in formation of lamellipodia in eukaryotic cells.

  19. Suppression of T cell-induced osteoclast formation

    SciTech Connect

    Karieb, Sahar; Fox, Simon W.

    2013-07-12

    Highlights: •Genistein and coumestrol prevent activated T cell induced osteoclast formation. •Anti-TNF neutralising antibodies prevent the pro-osteoclastic effect of activated T cells. •Phytoestrogens inhibit T cell derived TNF alpha and inflammatory cytokine production. •Phytoestrogens have a broader range of anti-osteoclastic actions than other anti-resorptives. -- Abstract: Inhibition of T cell derived cytokine production could help suppress osteoclast differentiation in inflammatory skeletal disorders. Bisphosphonates are typically prescribed to prevent inflammatory bone loss but are not tolerated by all patients and are associated with an increased risk of osteonecrosis of the jaw. In light of this other anti-resorptives such as phytoestrogens are being considered. However the effect of phytoestrogens on T cell-induced osteoclast formation is unclear. The effect of genistein and coumestrol on activated T cell-induced osteoclastogenesis and cytokine production was therefore examined. Concentrations of genistein and coumestrol (10{sup −7} M) previously shown to directly inhibit osteoclast formation also suppressed the formation of TRAP positive osteoclast induced by con A activated T cells, which was dependent on inhibition of T cell derived TNF-α. While both reduced osteoclast formation their mechanism of action differed. The anti-osteoclastic effect of coumestrol was associated with a dual effect on con A induced T cell proliferation and activation; 10{sup −7} M coumestrol significantly reducing T cell number (0.36) and TNF-α (0.47), IL-1β (0.23) and IL-6 (0.35) expression, whereas genistein (10{sup −7} M) had no effect on T cell number but a more pronounced effect on T cell differentiation reducing expression of TNF-α (0.49), IL-1β (0.52), IL-6 (0.71) and RANKL (0.71). Phytoestrogens therefore prevent the pro-osteoclastic action of T cells suggesting they may have a role in the control of inflammatory bone loss.

  20. Signaling events in pathogen-induced macrophage foam cell formation.

    PubMed

    Shaik-Dasthagirisaheb, Yazdani B; Mekasha, Samrawit; He, Xianbao; Gibson, Frank C; Ingalls, Robin R

    2016-08-01

    Macrophage foam cell formation is a key event in atherosclerosis. Several triggers induce low-density lipoprotein (LDL) uptake by macrophages to create foam cells, including infections with Porphyromonas gingivalis and Chlamydia pneumoniae, two pathogens that have been linked to atherosclerosis. While gene regulation during foam cell formation has been examined, comparative investigations to identify shared and specific pathogen-elicited molecular events relevant to foam cell formation are not well documented. We infected mouse bone marrow-derived macrophages with P. gingivalis or C. pneumoniae in the presence of LDL to induce foam cell formation, and examined gene expression using an atherosclerosis pathway targeted plate array. We found over 30 genes were significantly induced in response to both pathogens, including PPAR family members that are broadly important in atherosclerosis and matrix remodeling genes that may play a role in plaque development and stability. Six genes mainly involved in lipid transport were significantly downregulated. The response overall was remarkably similar and few genes were regulated in a pathogen-specific manner. Despite very divergent lifestyles, P. gingivalis and C. pneumoniae activate similar gene expression profiles during foam cell formation that may ultimately serve as targets for modulating infection-elicited foam cell burden, and progression of atherosclerosis.

  1. The Formation of Germ Cell for Organizational Learning

    ERIC Educational Resources Information Center

    Ivaldi, Silvia; Scaratti, Giuseppe

    2016-01-01

    Purpose: The aim of the paper is to analyze the process of "germ cell" formation by framing it as an opportunity for promoting organizational learning and transformation. The paper aims to specifically answer two research questions: Why does the "germ cell" have a pivotal role in organization's transformation? and Which…

  2. Cell-fusion method to visualize interphase nuclear pore formation.

    PubMed

    Maeshima, Kazuhiro; Funakoshi, Tomoko; Imamoto, Naoko

    2014-01-01

    In eukaryotic cells, the nucleus is a complex and sophisticated organelle that organizes genomic DNA to support essential cellular functions. The nuclear surface contains many nuclear pore complexes (NPCs), channels for macromolecular transport between the cytoplasm and nucleus. It is well known that the number of NPCs almost doubles during interphase in cycling cells. However, the mechanism of NPC formation is poorly understood, presumably because a practical system for analysis does not exist. The most difficult obstacle in the visualization of interphase NPC formation is that NPCs already exist after nuclear envelope formation, and these existing NPCs interfere with the observation of nascent NPCs. To overcome this obstacle, we developed a novel system using the cell-fusion technique (heterokaryon method), previously also used to analyze the shuttling of macromolecules between the cytoplasm and the nucleus, to visualize the newly synthesized interphase NPCs. In addition, we used a photobleaching approach that validated the cell-fusion method. We recently used these methods to demonstrate the role of cyclin-dependent protein kinases and of Pom121 in interphase NPC formation in cycling human cells. Here, we describe the details of the cell-fusion approach and compare the system with other NPC formation visualization methods.

  3. JGOMAS: New Approach to AI Teaching

    ERIC Educational Resources Information Center

    Barella, A.; Valero, S.; Carrascosa, C.

    2009-01-01

    This paper presents a new environment for teaching practical work in AI subjects. The main purpose of this environment is to make AI techniques more appealing to students and to facilitate the use of the toolkits which are currently widely used in research and development. This new environment has a toolkit for developing and executing agents,…

  4. The Relevance of AI Research to CAI.

    ERIC Educational Resources Information Center

    Kearsley, Greg P.

    This article provides a tutorial introduction to Artificial Intelligence (AI) research for those involved in Computer Assisted Instruction (CAI). The general theme is that much of the current work in AI, particularly in the areas of natural language understanding systems, rule induction, programming languages, and socratic systems, has important…

  5. Nanopore formation in neuroblastoma cells following ultrashort electric pulse exposure

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Payne, Jason A.; Wilmink, Gerald J.; Ibey, Bennett L.

    2011-03-01

    Ultrashort or nanosecond electrical pulses (USEP) cause repairable damage to the plasma membranes of cells through formation of nanopores. These nanopores are able to pass small ions such as sodium, calcium, and potassium, but remain impermeable to larger molecules like trypan blue and propidium iodide. What remains uncertain is whether generation of nanopores by ultrashort electrical pulses can inhibit action potentials in excitable cells. In this paper, we explored the sensitivity of excitable cells to USEP using Calcium Green AM 1 ester fluorescence to measure calcium uptake indicative of nanopore formation in the plasma membrane. We determined the threshold for nanopore formation in neuroblastoma cells for three pulse parameters (amplitude, pulse width, and pulse number). Measurement of such thresholds will guide future studies to determine if USEP can inhibit action potentials without causing irreversible membrane damage.

  6. The role of Cbln1 on Purkinje cell synapse formation.

    PubMed

    Ito-Ishida, Aya; Okabe, Shigeo; Yuzaki, Michisuke

    2014-06-01

    Cbln1 is a glycoprotein which belongs to the C1q family. In the cerebellum, Cbln1 is produced and secreted from granule cells and works as a strong synapse organizer between Purkinje cells and parallel fibers, the axons of the granule cells. In this update article, we will describe the molecular mechanisms by which Cbln1 induces synapse formation and will review our findings on the axonal structural changes which occur specifically during this process. We will also describe our recent finding that Cbln1 has a suppressive role in inhibitory synapse formation between Purkinje cells and molecular layer interneurons. Our results have revealed that Cbln1 plays an essential role to establish parallel fiber-Purkinje cell synapses and to regulate balance between excitatory and inhibitory input on Purkinje cells.

  7. Enhanced product formation in continuous fermentations with microbial cell recycle

    SciTech Connect

    Bull, D.N.; Young, M.D.

    1981-02-01

    The effect of partial recycle of microbial cells on the operation of a chemostat has been investigated for two fermentations. Stable steady states with and without partial cell recycle were obtained for the conversion of d-sorbitol to L-sorbose by Gluconobacter oxydans subsp. suboxydans 1916B and for the conversion of glucose to 2-ketogluconic acid by Serratia marcescens NRRl B-486. The employment of partial cell recycle dramatically increased product formation rates for both fermentations.

  8. Is traumatic axonal injury (AI) associated with an early microglial activation? Application of a double-labeling technique for simultaneous detection of microglia and AI.

    PubMed

    Oehmichen, M; Theuerkauf, I; Meissner, C

    1999-05-01

    The aim of the present study was to determine whether axonal injury (AI) induces a microglial reaction within 15 days after brain trauma. In 40 selected cases of confirmed AI, the topographical relation of AI and microglial reaction was assessed using an immunohistochemical double-labeling technique for simultaneous demonstration of AI using beta-amyloid precursor protein (beta-APP) antibody and of microglia using CD68 antibody. Although traumatic injury was usually followed by a moderate early diffuse rise in the number of CD68-reactive cells in the white matter, increases in macrophages in areas of AI accumulation were only sporadic and did not occur until after 4 days. At survival intervals of 5-15 days a moderate microglial reaction in regions of beta-APP-positive injured axons was detected, at maximum, in half of the case material. During this interval AI-associated satellitosis-like clusters or stars described by other authors after a survival time of more than 7 weeks were an isolated phenomenon. The prolonged microglial reaction as well as the reduction of beta-APP-positive AI during longer survival periods supports the hypothesis that AI is not primarily chemotactically attractive and that the damage to a portion of beta-APPstained axons may be partly reversible. Most cases clearly require a prolonged interval of more than 15 days before initiation of the final scavenger reaction. For forensic purposes the increase in the number of microglial cells within the region of AI accumulation after a survival time of more than 5 days and the multiple and distinct demonstration of star-like microglial reactions within the white matter after survival times exceeding 7 weeks may provide valuable postmortem information on the timing of a traumatic event.

  9. Chinese Herbal Medicine Fuzheng Kang-Ai Decoction Inhibited Lung Cancer Cell Growth through AMPKα-Mediated Induction and Interplay of IGFBP1 and FOXO3a

    PubMed Central

    Zheng, Fang; Wu, Jingjing; Li, Xiong; Tang, Qing; Yang, LiJun; Yang, Xiaobing; Wu, WanYin

    2016-01-01

    The aim of this study is to investigate the actions of Chinese herbal medicine, called “Fuzheng Kang-Ai” (FZKA for short) decoction, against non-small cell lung cancer (NSCLC) and its mechanisms in vitro and in vivo. We showed that the effect of FZKA decoction significantly inhibited growth of A549 and PC9 cells. Furthermore, FZKA increased phosphorylation of AMP-activated protein kinase alpha (AMPKα) and induced protein expression of insulin-like growth factor (IGF) binding protein 1 (IGFBP1) and forkhead homeobox type O3a (FOXO3a). The specific inhibitor of AMPKα (Compound C) blocked FZKA-induced protein expression of IGFBP1 and FOXO3a. Interestingly, silencing of IGFBP1 and FOXO3a overcame the inhibitory effect of FZKA on cell growth. Moreover, silencing of IGFBP1 attenuated the effect of FZKA decoction on FOXO3a expression, and exogenous expression of FOXO3a enhanced the FZKA-stimulated phosphorylation of AMPKα. Accordingly, FZKA inhibited the tumor growth in xenograft nude mice model. Collectively, our results show that FZKA decoction inhibits proliferation of NSCLC cells through activation of AMPKα, followed by induction of IGFBP1 and FOXO3a proteins. Exogenous expression of FOXO3a feedback enhances FZKA decoction-stimulated IGFBP1 expression and phosphorylation of AMPKα. The reciprocal interplay of IGFBP1 and FOXO3a contribute to the overall responses of FAKA decoction. PMID:27057199

  10. Insulin-Mediated Downregulation of Apolipoprotein A-I Gene in Human Hepatoma Cell Line HepG2: The Role of Interaction Between FOXO1 and LXRβ Transcription Factors.

    PubMed

    Shavva, Vladimir S; Bogomolova, Alexandra M; Nikitin, Artemy A; Dizhe, Ella B; Tanyanskiy, Dmitry A; Efremov, Alexander M; Oleinikova, Galina N; Perevozchikov, Andrej P; Orlov, Sergey V

    2017-02-01

    Apolipoprotein A-I (ApoA-I) is a key component of high density lipoproteins which possess anti-atherosclerotic and anti-inflammatory properties. Insulin is a crucial mediator of the glucose and lipid metabolism that has been implicated in atherosclerotic and inflammatory processes. Important mediators of insulin signaling such as Liver X Receptors (LXRs) and Forkhead Box A2 (FOXA2) are known to regulate apoA-I expression in liver. Forkhead Box O1 (FOXO1) is a well-known target of insulin signaling and a key mediator of oxidative stress response. Low doses of insulin were shown to activate apoA-I expression in human hepatoma HepG2 cells. However, the detailed mechanisms for these processes are still unknown. We studied the possible involvement of FOXO1, FOXA2, LXRα, and LXRβ transcription factors in the insulin-mediated regulation of apoA-I expression. Treatment of HepG2 cells with high doses of insulin (48 h, 100 nM) suppresses apoA-I gene expression. siRNAs against FOXO1, FOXA2, LXRβ, or LXRα abrogated this effect. FOXO1 forms a complex with LXRβ and insulin treatment impairs FOXO1/LXRβ complex binding to hepatic enhancer and triggers its nuclear export. Insulin as well as LXR ligand TO901317 enhance the interaction between FOXA2, LXRα, and hepatic enhancer. These data suggest that high doses of insulin downregulate apoA-I gene expression in HepG2 cells through redistribution of FOXO1/LXRβ complex, FOXA2, and LXRα on hepatic enhancer of apoA-I gene. J. Cell. Biochem. 118: 382-396, 2017. © 2016 Wiley Periodicals, Inc.

  11. Germ cell formation from embryonic stem cells and the use of somatic cell nuclei in oocytes.

    PubMed

    Pelosi, Emanuele; Forabosco, Antonino; Schlessinger, David

    2011-03-01

    Embryonic stem cells (ESCs) have remarkable properties of pluripotency and self-renewal, along with the retention of chromosomal integrity. Germ cells function as a kind of "transgenerational stem cells," transmitting genetic information from one generation to the next. The formation of putative primordial germ cells (PGCs) and germ cells from mouse and human ESCs (hESCs) has, in fact, been shown, and the apparent derivation of functional mouse male gametes has also been described. Additionally, investigators have successfully reprogrammed somatic nuclei into a pluripotent state by inserting them into ESCs or oocytes. This would enable the generation of ESCs genetically identical to the somatic cell donor and their use in cell therapy. However, these methodologies are still inefficient and their mechanisms poorly understood. Until full comprehension of these processes is obtained, clinical applications remain remote. Nevertheless, they represent promising tools in the future, enhancing methods of therapeutic cloning and infertility treatment.

  12. Defective removal of cellular cholesterol and phospholipids by apolipoprotein A-I in Tangier Disease.

    PubMed Central

    Francis, G A; Knopp, R H; Oram, J F

    1995-01-01

    Tangier disease is a rare genetic disorder characterized by extremely low plasma levels of HDL and apo A-I, deposition of cholesteryl esters in tissues, and a high prevalence of cardiovascular disease. We examined the possibility that HDL apolipoprotein-mediated removal of cellular lipids may be defective in Tangier disease. With fibroblasts from normal subjects, purified apo A-I cleared cells of cholesteryl esters, depleted cellular free cholesterol pools available for esterification, and stimulated efflux of radiolabeled cholesterol, phosphatidylcholine, and sphingomyelin. With fibroblasts from two unrelated Tangier patients, however, apo A-I had little or no effect on any of these lipid transport processes. Intact HDL also was unable to clear cholesteryl esters from Tangier cells even though it promoted radiolabeled cholesterol efflux to levels 50-70% normal. Passive desorption of radiolabeled cholesterol or phospholipids into medium containing albumin or trypsinized HDL was normal for Tangier cells. Binding studies showed that the interaction of apo A-I with high-affinity binding sites on Tangier fibroblasts was abnormal. These results indicate that apo A-I has an impaired ability to remove cholesterol and phospholipid from Tangier fibroblasts, possibly because of a defective interaction of apo A-I with cell-surface binding sites. Failure of apo A-I to acquire cellular lipids may account for the rapid catabolism of nascent HDL particles and the low plasma HDL levels in Tangier disease. Images PMID:7615839

  13. Pulp stem cells: implication in reparative dentin formation.

    PubMed

    Dimitrova-Nakov, Sasha; Baudry, Anne; Harichane, Yassine; Kellermann, Odile; Goldberg, Michel

    2014-04-01

    Many dental pulp stem cells are neural crest derivatives essential for lifelong maintenance of tooth functions and homeostasis as well as tooth repair. These cells may be directly implicated in the healing process or indirectly involved in cell-to-cell diffusion of paracrine messages to resident (pulpoblasts) or nonresident cells (migrating mesenchymal cells). The identity of the pulp progenitors and the mechanisms sustaining their regenerative capacity remain largely unknown. Taking advantage of the A4 cell line, a multipotent stem cell derived from the molar pulp of mouse embryo, we investigated the capacity of these pulp-derived precursors to induce in vivo the formation of a reparative dentin-like structure upon implantation within the pulp of a rodent incisor or a first maxillary molar after surgical exposure. One month after the pulp injury alone, a nonmineralized fibrous matrix filled the mesial part of the coronal pulp chamber. Upon A4 cell implantation, a mineralized osteodentin was formed in the implantation site without affecting the structure and vitality of the residual pulp in the central and distal parts of the pulp chamber. These results show that dental pulp stem cells can induce the formation of reparative dentin and therefore constitute a useful tool for pulp therapies. Finally, reparative dentin was also built up when A4 progenitors were performed by alginate beads, suggesting that alginate is a suitable carrier for cell implantation in teeth.

  14. Apolipoprotein A-I mimetic peptides inhibit expression and activity of hypoxia-inducible factor-1α in human ovarian cancer cell lines and a mouse ovarian cancer model.

    PubMed

    Gao, Feng; Chattopadhyay, Arnab; Navab, Mohamad; Grijalva, Victor; Su, Feng; Fogelman, Alan M; Reddy, Srinivasa T; Farias-Eisner, Robin

    2012-08-01

    Our previous results demonstrated that the apolipoprotein A-I (apoA-I) mimetic peptides L-4F and L-5F inhibit vascular endothelial growth factor production and tumor angiogenesis. The present study was designed to test whether apoA-I mimetic peptides inhibit the expression and activity of hypoxia-inducible factor-1α (HIF-1α), which plays a critical role in the production of angiogenic factors and angiogenesis. Immunohistochemistry staining was used to examine the expression of HIF-1α in tumor tissues. Immunoblotting, real-time polymerase chain reaction, immunofluorescence, and luciferase activity assays were used to determine the expression and activity of HIF-1α in human ovarian cancer cell lines. Immunohistochemistry staining demonstrated that L-4F treatment dramatically decreased HIF-1α expression in mouse ovarian tumor tissues. L-4F inhibited the expression and activity of HIF-1α induced by low oxygen concentration, cobalt chloride (CoCl(2), a hypoxia-mimic compound), lysophosphatidic acid, and insulin in two human ovarian cancer cell lines, OV2008 and CAOV-3. L-4F had no effect on the insulin-induced phosphorylation of Akt, but inhibited the activation of extracellular signal-regulated kinase and p70s6 kinase, leading to the inhibition of HIF-1α synthesis. Pretreatment with L-4F dramatically accelerated the proteasome-dependent protein degradation of HIF-1α in both insulin- and CoCl(2)-treated cells. The inhibitory effect of L-4F on HIF-1α expression is in part mediated by the reactive oxygen species-scavenging effect of L-4F. ApoA-I mimetic peptides inhibit the expression and activity of HIF-1α in both in vivo and in vitro models, suggesting the inhibition of HIF-1α may be a critical mechanism responsible for the suppression of tumor progression by apoA-I mimetic peptides.

  15. Improved Wide Operating Temperature Range of LiNiCoAiO2-based Li-ion Cells with Methyl Propionate-based Electrolytes

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Tomcsi, Michael R.; Hwang, C.; Whitcanack, L. D.; Bugga, Ratnakumar V.; Nagata, Mikito; Visco, Vince; Tsukamoto, Hisashi

    2012-01-01

    Demonstration of wide operating temperature range Li-ion electrolytes Methyl propionate-based wide operating temperature range electrolytes were demonstrated to provide dramatic improvement of the low temperature capability of Quallion prototype Li-ion cells (MCMB-LiNiCoAlO2). Some formulations were observed to deliver over 60% of the room temperature capacity using a 5C rate at - 40oC !! Represents over a 4-fold improvement over the baseline electrolyte system. Demonstrated operational capability of a number of systems over a wide temperature range (-40 to +70 C) Demonstrated reasonably good long term cycle life performance at high temperature (i.e., at +40deg and +50 C) A number of formulations containing electrolytes additives (i.e., FEC, VC, LiBOB, and lithium oxalate) have been shown to have enhanced lithium kinetics at low temperature and promising high temperature resilience. Demonstrated good performance in larger capacity (12 Ah) Quallion Li-ion cells with methyl propionate-based electrolytes. Current efforts focused upon performing life studies and the impact upon low temperature capability.

  16. Artificial intelligence. Fears of an AI pioneer.

    PubMed

    Russell, Stuart; Bohannon, John

    2015-07-17

    From the enraged robots in the 1920 play R.U.R. to the homicidal computer H.A.L. in 2001: A Space Odyssey, science fiction writers have embraced the dark side of artificial intelligence (AI) ever since the concept entered our collective imagination. Sluggish progress in AI research, especially during the “AI winter” of the 1970s and 1980s, made such worries seem far-fetched. But recent breakthroughs in machine learning and vast improvements in computational power have brought a flood of research funding— and fresh concerns about where AI may lead us. One researcher now speaking up is Stuart Russell, a computer scientist at the University of California, Berkeley, who with Peter Norvig, director of research at Google, wrote the premier AI textbook, Artificial Intelligence: A Modern Approach, now in its third edition. Last year, Russell joined the Centre for the Study of Existential Risk at Cambridge University in the United Kingdom as an AI expert focusing on “risks that could lead to human extinction.” Among his chief concerns, which he aired at an April meeting in Geneva, Switzerland, run by the United Nations, is the danger of putting military drones and weaponry under the full control of AI systems. This interview has been edited for clarity and brevity.

  17. Formation of a cylindrical bridge in cell division

    NASA Astrophysics Data System (ADS)

    Citron, Daniel; Schmidt, Laura E.; Reichl, Elizabeth; Ren, Yixin; Robinson, Douglas; Zhang, Wendy W.

    2007-11-01

    In nature, the shape transition associated with the division of a mother cell into two daughter cells proceeds via a variety of routes. In the cylinder-thinning route, which has been observed in Dictyostelium and most animal cells, the mother cell first forms a broad bridge-like region, also known as a furrow, between two daughter cells. The furrow then rapidly evolves into a cylindrical bridge, which thins and eventually severs the mother cell into two. The fundamental mechanism underlying this division route is not understood. Recent experiments on Dictyostelium found that, while the cylinder-thinning route persists even when key actin cross-linking proteins are missing, it is disrupted by the removal of force-generating myosin-II proteins. Other measurements revealed that mutant cells lacking myosin-II have a much more uniform tension over the cell surface than wild-type cells. This suggests that tension variation may be important. Here we use a fluid model, previously shown to reproduce the thinning dynamics [Zhang & Robinson, PNAS 102, 7186 (2005)], to test this idea. Consistent with the experiments, the model shows that the cylinder formation process occurs regardless of the exact viscoelastic properties of the cell. In contrast to the experiments, a tension variation in the model hinders, rather then expedites, the cylinder formation.

  18. Cell Adhesion in Epidermal Development and Barrier Formation

    PubMed Central

    Sumigray, Kaelyn D.; Lechler, Terry

    2015-01-01

    Cell–cell adhesions are necessary for structural integrity and barrier formation of the epidermis. Here, we discuss insights from genetic and cell biological studies into the roles of individual cell–cell junctions and their composite proteins in regulating epidermal development and function. In addition to individual adhesive functions, we will discuss emerging ideas on mechanosensation/transduction of junctions in the epidermis, noncanonical roles for adhesion proteins, and crosstalk/interdependencies between the junctional systems. These studies have revealed that cell adhesion proteins are connected to many aspects of tissue physiology including growth control, differentiation, and inflammation. PMID:25733147

  19. Modeling cell-death patterning during biofilm formation

    NASA Astrophysics Data System (ADS)

    Ghosh, Pushpita; Ben-Jacob, Eshel; Levine, Herbert

    2013-12-01

    Self-organization by bacterial cells often leads to the formation of a highly complex spatially-structured biofilm. In such a bacterial biofilm, cells adhere to each other and are embedded in a self-produced extracellular matrix (ECM). Bacillus substilis bacteria utilize localized cell-death patterns which focuses mechanical forces to form wrinkled sheet-like structures in three dimensions. A most intriguing feature underlying this biofilm formation is that vertical buckling and ridge location is biased to occur in region of high cell-death. Here we present a spatially extended model to investigate the role of the bacterial secreted ECM during the biofilm formation and the self-organization of cell-death. Using this reaction-diffusion model we show that the interaction between the cell's motion and the ECM concentration gives rise to a self-trapping instability, leading to variety of cell-death patterns. The resultant spot patterns generated by our model are shown to be in semi-quantitative agreement with recent experimental observation.

  20. Aggregation of red blood cells: From rouleaux to clot formation

    NASA Astrophysics Data System (ADS)

    Wagner, Christian; Steffen, Patrick; Svetina, Saša

    2013-06-01

    Red blood cells are known to form aggregates in the form of rouleaux. This aggregation process is believed to be reversible, but there is still no full understanding on the adhesion mechanism. There are at least two competing models, based either on bridging or on depletion. We review recent experimental results on the single cell level and theoretical analyses of the depletion model and of the influence of the cell shape on the adhesion strength. Another important aggregation mechanism is caused by activation of platelets. This leads to clot formation which is life-saving in the case of wound healing, but also a major cause of death in the case of a thrombus induced stroke. We review historical and recent results on the participation of red blood cells in clot formation.

  1. Human papillomavirus 16 E5 induces bi-nucleated cell formation by cell-cell fusion

    SciTech Connect

    Hu Lulin; Plafker, Kendra; Vorozhko, Valeriya; Zuna, Rosemary E.; Hanigan, Marie H.; Gorbsky, Gary J.; Plafker, Scott M.; Angeletti, Peter C.; Ceresa, Brian P.

    2009-02-05

    Human papillomaviruses (HPV) 16 is a DNA virus encoding three oncogenes - E5, E6, and E7. The E6 and E7 proteins have well-established roles as inhibitors of tumor suppression, but the contribution of E5 to malignant transformation is controversial. Using spontaneously immortalized human keratinocytes (HaCaT cells), we demonstrate that expression of HPV16 E5 is necessary and sufficient for the formation of bi-nucleated cells, a common characteristic of precancerous cervical lesions. Expression of E5 from non-carcinogenic HPV6b does not produce bi-nucleate cells. Video microscopy and biochemical analyses reveal that bi-nucleates arise through cell-cell fusion. Although most E5-induced bi-nucleates fail to propagate, co-expression of HPV16 E6/E7 enhances the proliferation of these cells. Expression of HPV16 E6/E7 also increases bi-nucleated cell colony formation. These findings identify a new role for HPV16 E5 and support a model in which complementary roles of the HPV16 oncogenes lead to the induction of carcinogenesis.

  2. A model of lipid-free Apolipoprotein A-I revealed by iterative molecular dynamics simulation

    SciTech Connect

    Zhang, Xing; Lei, Dongsheng; Zhang, Lei; Rames, Matthew; Zhang, Shengli

    2015-03-20

    Apolipoprotein A-I (apo A-I), the major protein component of high-density lipoprotein, has been proven inversely correlated to cardiovascular risk in past decades. The lipid-free state of apo A-I is the initial stage which binds to lipids forming high-density lipoprotein. Molecular models of lipid-free apo A-I have been reported by methods like X-ray crystallography and chemical cross-linking/mass spectrometry (CCL/MS). Through structural analysis we found that those current models had limited consistency with other experimental results, such as those from hydrogen exchange with mass spectrometry. Through molecular dynamics simulations, we also found those models could not reach a stable equilibrium state. Therefore, by integrating various experimental results, we proposed a new structural model for lipidfree apo A-I, which contains a bundled four-helix N-terminal domain (1–192) that forms a variable hydrophobic groove and a mobile short hairpin C-terminal domain (193–243). This model exhibits an equilibrium state through molecular dynamics simulation and is consistent with most of the experimental results known from CCL/MS on lysine pairs, fluorescence resonance energy transfer and hydrogen exchange. This solution-state lipid-free apo A-I model may elucidate the possible conformational transitions of apo A-I binding with lipids in high-density lipoprotein formation.

  3. A model of lipid-free Apolipoprotein A-I revealed by iterative molecular dynamics simulation

    DOE PAGES

    Zhang, Xing; Lei, Dongsheng; Zhang, Lei; ...

    2015-03-20

    Apolipoprotein A-I (apo A-I), the major protein component of high-density lipoprotein, has been proven inversely correlated to cardiovascular risk in past decades. The lipid-free state of apo A-I is the initial stage which binds to lipids forming high-density lipoprotein. Molecular models of lipid-free apo A-I have been reported by methods like X-ray crystallography and chemical cross-linking/mass spectrometry (CCL/MS). Through structural analysis we found that those current models had limited consistency with other experimental results, such as those from hydrogen exchange with mass spectrometry. Through molecular dynamics simulations, we also found those models could not reach a stable equilibrium state. Therefore,more » by integrating various experimental results, we proposed a new structural model for lipidfree apo A-I, which contains a bundled four-helix N-terminal domain (1–192) that forms a variable hydrophobic groove and a mobile short hairpin C-terminal domain (193–243). This model exhibits an equilibrium state through molecular dynamics simulation and is consistent with most of the experimental results known from CCL/MS on lysine pairs, fluorescence resonance energy transfer and hydrogen exchange. This solution-state lipid-free apo A-I model may elucidate the possible conformational transitions of apo A-I binding with lipids in high-density lipoprotein formation.« less

  4. In vitro myelin formation using embryonic stem cells

    PubMed Central

    Kerman, Bilal E.; Kim, Hyung Joon; Padmanabhan, Krishnan; Mei, Arianna; Georges, Shereen; Joens, Matthew S.; Fitzpatrick, James A. J.; Jappelli, Roberto; Chandross, Karen J.; August, Paul; Gage, Fred H.

    2015-01-01

    Myelination in the central nervous system is the process by which oligodendrocytes form myelin sheaths around the axons of neurons. Myelination enables neurons to transmit information more quickly and more efficiently and allows for more complex brain functions; yet, remarkably, the underlying mechanism by which myelination occurs is still not fully understood. A reliable in vitro assay is essential to dissect oligodendrocyte and myelin biology. Hence, we developed a protocol to generate myelinating oligodendrocytes from mouse embryonic stem cells and established a myelin formation assay with embryonic stem cell-derived neurons in microfluidic devices. Myelin formation was quantified using a custom semi-automated method that is suitable for larger scale analysis. Finally, early myelination was followed in real time over several days and the results have led us to propose a new model for myelin formation. PMID:26015546

  5. Open-cell cloud formation over the Bahamas

    NASA Technical Reports Server (NTRS)

    2002-01-01

    What atmospheric scientists refer to as open cell cloud formation is a regular occurrence on the back side of a low-pressure system or cyclone in the mid-latitudes. In the Northern Hemisphere, a low-pressure system will draw in surrounding air and spin it counterclockwise. That means that on the back side of the low-pressure center, cold air will be drawn in from the north, and on the front side, warm air will be drawn up from latitudes closer to the equator. This movement of an air mass is called advection, and when cold air advection occurs over warmer waters, open cell cloud formations often result. This MODIS image shows open cell cloud formation over the Atlantic Ocean off the southeast coast of the United States on February 19, 2002. This particular formation is the result of a low-pressure system sitting out in the North Atlantic Ocean a few hundred miles east of Massachusetts. (The low can be seen as the comma-shaped figure in the GOES-8 Infrared image from February 19, 2002.) Cold air is being drawn down from the north on the western side of the low and the open cell cumulus clouds begin to form as the cold air passes over the warmer Caribbean waters. For another look at the scene, check out the MODIS Direct Broadcast Image from the University of Wisconsin. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  6. Solvent effect on columnar formation in solar-cell geometry

    NASA Astrophysics Data System (ADS)

    Park, J. H.; Sosa-Vargas, L.; Takanishi, Y.; Kim, K. H.; Kim, Y. S.; Park, Y. W.; Yamamoto, J.; Labardi, M.; Lagerwall, J. P. F.; Shimizu, Y.; Scalia, G.

    2016-03-01

    The efficiency of the conduction of photocurrent in discotic liquid crystals is known to depend on the quality of the columnar organization. Solvents have shown to be able to influence the formation of wire structures on substrates promoting very long and ordered wired formations or bulkier structures depending on the affinity of the solvent with parts of the molecular structure of discotics. Here we present a study on the effect of solvents when the liquid crystal is confined between two substrates with the columns running perpendicular to them, geometry used in solar cells. We focused on toluene and dodecane, solvents that have shown to promote on substrates the formation of aligned and long nanowires and bulk large and isolated fibers, respectively. The phase transition behavior indicates that toluene does not interfere with the columnar formation while dodecane strongly influence increasing the disorder in the structure.

  7. Mapping Fishing Effort through AIS Data

    PubMed Central

    Natale, Fabrizio; Gibin, Maurizio; Alessandrini, Alfredo; Vespe, Michele; Paulrud, Anton

    2015-01-01

    Several research initiatives have been undertaken to map fishing effort at high spatial resolution using the Vessel Monitoring System (VMS). An alternative to the VMS is represented by the Automatic Identification System (AIS), which in the EU became compulsory in May 2014 for all fishing vessels of length above 15 meters. The aim of this paper is to assess the uptake of the AIS in the EU fishing fleet and the feasibility of producing a map of fishing effort with high spatial and temporal resolution at European scale. After analysing a large AIS dataset for the period January-August 2014 and covering most of the EU waters, we show that AIS was adopted by around 75% of EU fishing vessels above 15 meters of length. Using the Swedish fleet as a case study, we developed a method to identify fishing activity based on the analysis of individual vessels’ speed profiles and produce a high resolution map of fishing effort based on AIS data. The method was validated using detailed logbook data and proved to be sufficiently accurate and computationally efficient to identify fishing grounds and effort in the case of trawlers, which represent the largest portion of the EU fishing fleet above 15 meters of length. Issues still to be addressed before extending the exercise to the entire EU fleet are the assessment of coverage levels of the AIS data for all EU waters and the identification of fishing activity in the case of vessels other than trawlers. PMID:26098430

  8. Multiwell cell culture plate format with integrated microfluidic perfusion system

    NASA Astrophysics Data System (ADS)

    Domansky, Karel; Inman, Walker; Serdy, Jim; Griffith, Linda G.

    2006-01-01

    A new cell culture analog has been developed. It is based on the standard multiwell cell culture plate format but it provides perfused three-dimensional cell culture capability. The new capability is achieved by integrating microfluidic valves and pumps into the plate. The system provides a means to conduct high throughput assays for target validation and predictive toxicology in the drug discovery and development process. It can be also used for evaluation of long-term exposure to drugs or environmental agents or as a model to study viral hepatitis, cancer metastasis, and other diseases and pathological conditions.

  9. Polydatin Inhibits Formation of Macrophage-Derived Foam Cells

    PubMed Central

    Wu, Min; Liu, Meixia; Guo, Gang; Zhang, Wengao; Liu, Longtao

    2015-01-01

    Rhizoma Polygoni Cuspidati, a Chinese herbal medicine, has been widely used in traditional Chinese medicine for a long time. Polydatin, one of the major active ingredients in Rhizoma Polygoni Cuspidati, has been recently shown to possess extensive cardiovascular pharmacological activities. In present study, we examined the effects of Polydatin on the formation of peritoneal macrophage-derived foam cells in Apolipoprotein E gene knockout mice (ApoE−/−) and explored the potential underlying mechanisms. Peritoneal macrophages were collected from ApoE−/− mice and cultured in vitro. These cells sequentially were divided into four groups: Control group, Model group, Lovastatin group, and Polydatin group. Our results demonstrated that Polydatin significantly inhibits the formation of foam cells derived from peritoneal macrophages. Further studies indicated that Polydatin regulates the metabolism of intracellular lipid and possesses anti-inflammatory effects, which may be regulated through the PPAR-γ signaling pathways. PMID:26557864

  10. Status of AIS Frequencies Nationally and Internationally: Improving Satellite Detection of AIS

    DTIC Science & Technology

    2008-09-04

    International Telecommunications Union? • ITU 2007 World Radio Conference – Authorized AIS 1 & AIS 2 as satellite uplink frequencies, on secondary basis...Collision Rate “AIS as is” How do results correlate with predictions? Satellite Detection Statistics with Correlation Processing – ITU -R Rep M.2084 (JSC...Status of AIS Frequencies  Nationally and  Internationally: Improving  satellite  detection of AIS CG‐622 | Joe Hersey Chief, Spectrum Mgt Div USCG

  11. Smooth Muscle Cell Foam Cell Formation, Apolipoproteins, and ABCA1 in Intracranial Aneurysms: Implications for Lipid Accumulation as a Promoter of Aneurysm Wall Rupture.

    PubMed

    Ollikainen, Eliisa; Tulamo, Riikka; Lehti, Satu; Lee-Rueckert, Miriam; Hernesniemi, Juha; Niemelä, Mika; Ylä-Herttuala, Seppo; Kovanen, Petri T; Frösen, Juhana

    2016-07-01

    Saccular intracranial aneurysm (sIA) aneurysm causes intracranial hemorrhages that are associated with high mortality. Lipid accumulation and chronic inflammation occur in the sIA wall. A major mechanism for lipid clearance from arteries is adenosine triphosphate-binding cassette A1 (ABCA1)-mediated lipid efflux from foam cells to apolipoprotein A-I (apoA-I). We investigated the association of wall degeneration, inflammation, and lipid-related parameters in tissue samples of 16 unruptured and 20 ruptured sIAs using histology and immunohistochemistry. Intracellular lipid accumulation was associated with wall remodeling (p = 0.005) and rupture (p = 0.020). Foam cell formation was observed in smooth muscle cells, in addition to CD68- and CD163-positive macrophages. Macrophage infiltration correlated with intracellular lipid accumulation and apolipoproteins, including apoA-I. ApoA-I correlated with markers of lipid accumulation and wall degeneration (p = 0.01). ApoA-I-positive staining colocalized with ABCA1-positive cells particularly in sIAs with high number of smooth muscle cells (p = 0.003); absence of such colocalization was associated with wall degeneration (p = 0.017). Known clinical risk factors for sIA rupture correlated inversely with apoA-I. We conclude that lipid accumulation associates with sIA wall degeneration and risk of rupture, possibly via formation of foam cells and subsequent loss of mural cells. Reduced removal of lipids from the sIA wall via ABCA1-apoA-I pathway may contribute to this process.

  12. Crystal structures of the LsrR proteins complexed with phospho-AI-2 and two signal-interrupting analogues reveal distinct mechanisms for ligand recognition.

    PubMed

    Ha, Jung-Hye; Eo, Yumi; Grishaev, Alexander; Guo, Min; Smith, Jacqueline A I; Sintim, Herman O; Kim, Eun-Hee; Cheong, Hae-Kap; Bentley, William E; Ryu, Kyoung-Seok

    2013-10-16

    Quorum sensing (QS) is a cell-to-cell communication system responsible for a variety of bacterial phenotypes including virulence and biofilm formation. QS is mediated by small molecules, autoinducers (AIs), including AI-2 that is secreted by both Gram-positive and -negative microbes. LsrR is a key transcriptional regulator that governs the varied downstream processes by perceiving AI-2 signal, but its activation via autoinducer-binding remains poorly understood. Here, we provide detailed regulatory mechanism of LsrR from the crystal structures in complexes with the native signal (phospho-AI-2, D5P) and two quorum quenching antagonists (ribose-5-phosphate, R5P; phospho-isobutyl-AI-2, D8P). Interestingly, the bound D5P and D8P molecules are not the diketone forms but rather hydrated, and the hydrated moiety forms important H-bonds with the carboxylate of D243. The D5P-binding flipped out F124 of the binding pocket, and resulted in the disruption of the dimeric interface-1 by unfolding the α7 segment. However, the same movement of F124 by the D8P'-binding did not cause the unfolding of the α7 segment. Although the LsrR-binding affinity of R5P (Kd, ∼1 mM) is much lower than that of D5P and D8P (∼2.0 and ∼0.5 μM), the α-anomeric R5P molecule fits into the binding pocket without any structural perturbation, and thus stabilizes the LsrR tetramer. The binding of D5P, not D8P and R5P, disrupted the tetrameric structure and thus is able to activate LsrR. The detailed structural and mechanistic insights from this study could be useful for facilitating design of new antivirulence and antibiofilm agents based on LsrR.

  13. Graphene-Induced Pore Formation on Cell Membranes

    NASA Astrophysics Data System (ADS)

    Duan, Guangxin; Zhang, Yuanzhao; Luan, Binquan; Weber, Jeffrey K.; Zhou, Royce W.; Yang, Zaixing; Zhao, Lin; Xu, Jiaying; Luo, Judong; Zhou, Ruhong

    2017-02-01

    Examining interactions between nanomaterials and cell membranes can expose underlying mechanisms of nanomaterial cytotoxicity and guide the design of safer nanomedical technologies. Recently, graphene has been shown to exhibit potential toxicity to cells; however, the molecular processes driving its lethal properties have yet to be fully characterized. We here demonstrate that graphene nanosheets (both pristine and oxidized) can produce holes (pores) in the membranes of A549 and Raw264.7 cells, substantially reducing cell viability. Electron micrographs offer clear evidence of pores created on cell membranes. Our molecular dynamics simulations reveal that multiple graphene nanosheets can cooperate to extract large numbers of phospholipids from the membrane bilayer. Strong dispersion interactions between graphene and lipid-tail carbons result in greatly depleted lipid density within confined regions of the membrane, ultimately leading to the formation of water-permeable pores. This cooperative lipid extraction mechanism for membrane perforation represents another distinct process that contributes to the molecular basis of graphene cytotoxicity.

  14. Stromal cells in chronic inflammation and tertiary lymphoid organ formation.

    PubMed

    Buckley, Christopher D; Barone, Francesca; Nayar, Saba; Bénézech, Cecile; Caamaño, Jorge

    2015-01-01

    Inflammation is an unstable state. It either resolves or persists. Why inflammation persists and the factors that define tissue tropism remain obscure. Increasing evidence suggests that tissue-resident stromal cells not only provide positional memory but also actively regulate the differential accumulation of inflammatory cells within inflamed tissues. Furthermore, at many sites of chronic inflammation, structures that mimic secondary lymphoid tissues are observed, suggesting that chronic inflammation and lymphoid tissue formation share common activation programs. Similarly, blood and lymphatic endothelial cells contribute to tissue homeostasis and disease persistence in chronic inflammation. This review highlights our increasing understanding of the role of stromal cells in inflammation and summarizes the novel immunological role that stromal cells exert in the persistence of inflammatory diseases.

  15. Characterization of Commercial Li-ion Cells in Pouch Format

    NASA Technical Reports Server (NTRS)

    Jeevarajan, Judith

    2014-01-01

    The li-ion pouch design cells exhibit similar behavior under off-nominal conditions as those in metal cans that do not have the internal safety devices. Safety should be well characterized before batteries are designed. Some of the li-ion pouch cell designs studied in this program reacted most violently to overcharge conditions at the medium rates but were tolerant to overcharge at very low rates. Some pouch cell designs have higher tolerance to vacuum exposures than some others. A comparison of the pouch material itself does not show a correlation between this tolerance and the number of layers or composition of the pouch indicating that this is a property of the electrode stack design inside the pouch. Reduced pressure (8 to 10 psi) test environments show that the extent of capacity degradation under reduced pressure environments is much less than that observed under vacuum conditions. Lithium-ion Pouch format cells are not necessarily true polymer cells.

  16. Induction of platelet formation from megakaryocytoid cells by nitric oxide.

    PubMed

    Battinelli, E; Willoughby, S R; Foxall, T; Valeri, C R; Loscalzo, J

    2001-12-04

    Although the growth factors that regulate megakaryocytopoiesis are well known, the molecular determinants of platelet formation from mature megakaryocytes remain poorly understood. Morphological changes in megakaryocytes associated with platelet formation and removal of senescent megakaryocytes are suggestive of an apoptotic process. Previously, we have established that nitric oxide (NO) can induce apoptosis in megakaryocytoid cell lines. To determine whether there is an association between NO-induced apoptosis and platelet production, we exposed Meg-01 cells to S-nitrosoglutathione (GSNO) with or without thrombopoeitin (TPO) pretreatment and used flow cytometry and electron microscopy to assess platelet-sized particle formation. Meg-01 cells treated with TPO alone produced few platelet-sized particles (<3% of total counts), whereas treatment with GSNO alone produced a significant percentage of platelet-sized particles (22 +/- 4% of total counts); when combined with TPO pretreatment, however, GSNO led to a marked increase in platelet-sized particle production (48 +/- 3% of total counts). Electron microscopy confirmed that Meg-01 cells treated with TPO and GSNO yielded platelet-sized particles with morphological features specific for platelet forms. The platelet-sized particle population appears to be functional, because addition of calcium, fibrinogen, and thrombin receptor-activating peptide led to aggregation. These results demonstrate that NO facilitates platelet production, thereby establishing the essential role of NO in megakaryocyte development and thrombopoiesis.

  17. ERBB3 is required for metastasis formation of melanoma cells

    PubMed Central

    Tiwary, S; Preziosi, M; Rothberg, P G; Zeitouni, N; Corson, N; Xu, L

    2014-01-01

    Melanoma is curable when it is at an early phase but is lethal once it becomes metastatic. The recent development of BRAFV600E inhibitors (BIs) showed great promise in treating metastatic melanoma, but resistance developed quickly in the treated patients, and these inhibitors are not effective on melanomas that express wild-type BRAF. Alternative therapeutic strategies for metastatic melanoma are urgently needed. Here we report that ERBB3, a member of the epidermal growth factor receptor family, is required for the formation of lung metastasis from both the BI-sensitive melanoma cell line, MA-2, and the BI-resistant melanoma cell line, 451Lu-R. Further analyses revealed that ERBB3 does not affect the initial seeding of melanoma cells in lung but is required for their further development into overt metastases, indicating that ERBB3 might be essential for the survival of melanoma cells after they reach the lung. Consistent with this, the ERBB3 ligand, NRG1, is highly expressed in mouse lungs and induces ERBB3-depdnent phosphorylation of AKT in both MA-2 and 451Lu-R cells in vitro. These findings suggest that ERBB3 may serve as a target for treating metastatic melanomas that are resistant to BIs. In support of this, administration of the pan-ERBB inhibitor, canertinib, significantly suppresses the metastasis formation of BI-resistant melanoma cell lines. PMID:25000258

  18. Effect of supercooling and cell volume on intracellular ice formation.

    PubMed

    Prickett, Richelle C; Marquez-Curtis, Leah A; Elliott, Janet A W; McGann, Locksley E

    2015-04-01

    Intracellular ice formation (IIF) has been linked to death of cells cryopreserved in suspension. It has been assumed that cells can be supercooled by 2 to 10°C before IIF occurs, but measurements of the degree of supercooling that cells can tolerate are often confounded by changing extracellular temperature and solutions of different osmolality (which affect the cell volume). The purpose of this study was to examine how the incidence of IIF in the absence of cryoprotectants is affected by the degree of supercooling and cell volume. Human umbilical vein endothelial cells were suspended in isotonic (300 mOsm) and hypertonic (∼600 to 700 mOsm) solutions and exposed to supercooling ranging from 2 to 10°C before extracellular ice was nucleated. The number of cells undergoing IIF was examined in a cryostage (based on the darkening of cells upon intracellular freezing ("flashing")) as a function of the degree of supercooling, and cell survival post-thaw was assessed using a membrane integrity assay. We found that while the incidence of IIF increased with supercooling in both isotonic and hypertonic solutions, it was higher in the isotonic solution at any given degree of supercooling. Since cells in hypertonic solution were shrunken due to water efflux, we hypothesized that the difference in IIF behavior could be attributed to the decreased volume of cells in the hypertonic solution. Our results confirm that cells with a smaller diameter before extracellular ice nucleation have a decreased probability of IIF and suggest that cell volume could play a more significant role in the incidence of IIF than the extracellular ice nucleation temperature.

  19. Activated-Ion ETD (AI-ETD) Improves the Ability of ETD to Identify Peptides in a Complex Mixture

    PubMed Central

    Ledvina, Aaron R.; Beauchene, Nicole A.; McAlister, Graeme C.; Syka, John E. P.; Schwartz, Jae C.; Griep-Raming, Jens; Westphall, Michael S.; Coon, Joshua J.

    2010-01-01

    Using a modified ETD-enabled QLT mass spectrometer, we demonstrate the utility of IR activation concomitant with ETD ion-ion reactions (activated-ion ETD, AI-ETD). Analyzing 12 SCX fractions of a LysC digest of human cells (HS) using ETD, CAD, and AI-ETD, we find that AI-ETD generates 13,405 peptide spectral matches (PSMs) at a 1% false-discovery rate (1% FDR), surpassing both ETD (7,968) and CAD (10,904). We also analyze 12 SCX fractions of a tryptic HS digest and find that ETD produces 6,234 PSMs, AI-ETD 9,130 PSMs, and CAD 15,209 PSMs. Compared to ETcaD, AI-ETD generates ~80% more PSMs for tryptic whole cell lysate and ~50% more PSMs for LysC whole cell lysate. PMID:21062032

  20. Enhanced AIS receiver design for satellite reception

    NASA Astrophysics Data System (ADS)

    Clazzer, Federico; Lázaro, Francisco; Plass, Simon

    2016-12-01

    The possibility to detect Automatic Identification System (AIS) messages from low earth orbit (LEO) satellites paves the road for a plurality of new and unexplored services. Besides worldwide tracking of vessels, maritime traffic monitoring, analysis of vessel routes employing big data, and oceans monitoring are just few of the fields, where satellite-aided AIS is beneficial. Designed for ship-to-ship communication and collision avoidance, AIS satellite reception performs poorly in regions with a high density of vessels. This calls for the development of advanced satellite AIS receivers able to improve the decoding capabilities. In this context, our contribution focuses on the introduction of a new enhanced AIS receiver design and its performance evaluation. The enhanced receiver makes use of a coherent receiver for the low signal-to-noise ratio (SNR) region, while for medium to high SNRs, a differential Viterbi receiver is used. Additional novelty of our work is in the exploitation of previously decoded packets from one vessel that is still under the LEO reception range, to improve the vessel detection probability. The assessment of the performance against a common receiver is done making the use of a simple and tight model of the medium access (MAC) layer and the multi-packet reception (MPR) matrix for physical layer (PHY) representation. Performance results show the benefits of such enhanced receiver, especially when it is bundled with successive interference cancellation (SIC).

  1. A hydrodynamic microchip for formation of continuous cell chains

    NASA Astrophysics Data System (ADS)

    Khoshmanesh, Khashayar; Zhang, Wei; Tang, Shi-Yang; Nasabi, Mahyar; Soffe, Rebecca; Tovar-Lopez, Francisco J.; Rajadas, Jayakumar; Mitchell, Arnan

    2014-05-01

    Here, we demonstrate the unique features of a hydrodynamic based microchip for creating continuous chains of model yeast cells. The system consists of a disk shaped microfluidic structure, containing narrow orifices that connect the main channel to an array of spoke channels. Negative pressure provided by a syringe pump draws fluid from the main channel through the narrow orifices. After cleaning process, a thin layer of water is left between the glass substrate and the polydimethylsiloxane microchip, enabling leakage beneath the channel walls. A mechanical clamp is used to adjust the operation of the microchip. Relaxing the clamp allows leakage of liquid beneath the walls in a controllable fashion, leading to formation of a long cell chain evenly distributed along the channel wall. The unique features of the microchip are demonstrated by creating long chains of yeast cells and model 15 μm polystyrene particles along the side wall and analysing the hydrogen peroxide induced death of patterned cells.

  2. Aroma formation by immobilized yeast cells in fermentation processes.

    PubMed

    Nedović, V; Gibson, B; Mantzouridou, T F; Bugarski, B; Djordjević, V; Kalušević, A; Paraskevopoulou, A; Sandell, M; Šmogrovičová, D; Yilmaztekin, M

    2015-01-01

    Immobilized cell technology has shown a significant promotional effect on the fermentation of alcoholic beverages such as beer, wine and cider. However, genetic, morphological and physiological alterations occurring in immobilized yeast cells impact on aroma formation during fermentation processes. The focus of this review is exploitation of existing knowledge on the biochemistry and the biological role of flavour production in yeast for the biotechnological production of aroma compounds of industrial importance, by means of immobilized yeast. Various types of carrier materials and immobilization methods proposed for application in beer, wine, fruit wine, cider and mead production are presented. Engineering aspects with special emphasis on immobilized cell bioreactor design, operation and scale-up potential are also discussed. Ultimately, examples of products with improved quality properties within the alcoholic beverages are addressed, together with identification and description of the future perspectives and scope for cell immobilization in fermentation processes.

  3. Pyrintegrin Induces Soft Tissue Formation by Transplanted or Endogenous Cells

    PubMed Central

    Shah, Bhranti S.; Chen, Mo; Suzuki, Takahiro; Embree, Mildred; Kong, Kimi; Lee, Chang H.; He, Ling; Xiang, Lusai; Ahn, Jeffrey A.; Ding, Sheng; Mao, Jeremy J.

    2017-01-01

    Focal adipose deficiency, such as lipoatrophy, lumpectomy or facial trauma, is a formidable challenge in reconstructive medicine, and yet scarcely investigated in experimental studies. Here, we report that Pyrintegrin (Ptn), a 2,4-disubstituted pyrimidine known to promote embryonic stem cells survival, is robustly adipogenic and induces postnatal adipose tissue formation in vivo of transplanted adipose stem/progenitor cells (ASCs) and recruited endogenous cells. In vitro, Ptn stimulated human adipose tissue derived ASCs to differentiate into lipid-laden adipocytes by upregulating peroxisome proliferator-activated receptor (PPARγ) and CCAAT/enhancer-binding protein-α (C/EBPα), with differentiated cells increasingly secreting adiponectin, leptin, glycerol and total triglycerides. Ptn-primed human ASCs seeded in 3D-bioprinted biomaterial scaffolds yielded newly formed adipose tissue that expressed human PPARγ, when transplanted into the dorsum of athymic mice. Remarkably, Ptn-adsorbed 3D scaffolds implanted in the inguinal fat pad had enhanced adipose tissue formation, suggesting Ptn’s ability to induce in situ adipogenesis of endogenous cells. Ptn promoted adipogenesis by upregulating PPARγ and C/EBPα not only in adipogenesis induction medium, but also in chemically defined medium specifically for osteogenesis, and concurrently attenuated Runx2 and Osx via BMP-mediated SMAD1/5 phosphorylation. These findings suggest Ptn’s novel role as an adipogenesis inducer with a therapeutic potential in soft tissue reconstruction and augmentation. PMID:28128224

  4. Exocytosis of macrophage lysosomes leads to digestion of apoptotic adipocytes and foam cell formation[S

    PubMed Central

    Haka, Abigail S.; Barbosa-Lorenzi, Valéria C.; Lee, Hyuek Jong; Falcone, Domenick J.; Hudis, Clifford A.; Dannenberg, Andrew J.

    2016-01-01

    Many types of apoptotic cells are phagocytosed and digested by macrophages. Adipocytes can be hundreds of times larger than macrophages, so they are too large to be digested by conventional phagocytic processes. The nature of the interaction between macrophages and apoptotic adipocytes has not been studied in detail. We describe a cellular process, termed exophagy, that is important for macrophage clearance of dead adipocytes and adipose tissue homeostasis. Using mouse models of obesity, human tissue, and a cell culture model, we show that macrophages form hydrolytic extracellular compartments at points of contact with dead adipocytes using local actin polymerization. These compartments are acidic and contain lysosomal enzymes delivered by exocytosis. Uptake and complete degradation of adipocyte fragments, which are released by extracellular hydrolysis, leads to macrophage foam cell formation. Exophagy-mediated foam cell formation is a highly efficient means by which macrophages internalize large amounts of lipid, which may ultimately overwhelm the metabolic capacity of the macrophage. This process provides a mechanism for degradation of objects, such as dead adipocytes, that are too large to be phagocytosed by macrophages. PMID:27044658

  5. Mast cell mediators and peritoneal adhesion formation in the rat.

    PubMed

    Langer, J C; Liebman, S M; Monk, P K; Pelletier, G J

    1995-09-01

    We have previously shown that mast cell stabilization attenuates peritoneal adhesion formation in the rat. The present study investigated the mechanism of this protection. Adhesions were created in weanling rats using cecal scraping and application of 95% ethanol. Rats received specific blockers for the mast cell products histamine, serotonin (5HT), leukotriene D4, and platelet activating factor intraperitoneally 30 min before laparotomy and at the time of abdominal closure. Control animals received saline. Adhesions were assessed blindly 1 week later using a standardized scale. Adhesion formation was not affected by histamine blockade using combined mepyramine and ranitidine, 5-HT1 blockade using methysergide, 5-HT3 blockade using ondansetron, leukotriene D4 blockade using MK-571, or platelet activating factor blockade using WEB-2086. However, blockade of the 5-HT2 receptor using ketanserin resulted in significant dose-dependent attenuation of adhesions compared to saline. These data suggest that mast cells mediate peritoneal adhesion formation in the rat through release of serotonin acting on 5HT2 receptors. Further understanding of this process may lead to new strategies for the prevention of postoperative adhesions.

  6. AI-2 quorum-sensing inhibitors affect the starvation response and reduce virulence in several Vibrio species, most likely by interfering with LuxPQ.

    PubMed

    Brackman, Gilles; Celen, Shari; Baruah, Kartik; Bossier, Peter; Van Calenbergh, Serge; Nelis, Hans J; Coenye, Tom

    2009-12-01

    The increase of disease outbreaks caused by Vibrio species in aquatic organisms as well as in humans, together with the emergence of antibiotic resistance in Vibrio species, has led to a growing interest in alternative disease control measures. Quorum sensing (QS) is a mechanism for regulating microbial gene expression in a cell density-dependent way. While there is good evidence for the involvement of auto-inducer 2 (AI-2)-based interspecies QS in the control of virulence in multiple Vibrio species, only few inhibitors of this system are known. From the screening of a small panel of nucleoside analogues for their ability to disturb AI-2-based QS, an adenosine derivative with a p-methoxyphenylpropionamide moiety at C-3' emerged as a promising hit. Its mechanism of inhibition was elucidated by measuring the effect on bioluminescence in a series of Vibrio harveyi AI-2 QS mutants. Our results indicate that this compound, as well as a truncated analogue lacking the adenine base, block AI-2-based QS without interfering with bacterial growth. The active compounds affected neither the bioluminescence system as such nor the production of AI-2, but most likely interfered with the signal transduction pathway at the level of LuxPQ in V. harveyi. The most active nucleoside analogue (designated LMC-21) was found to reduce the Vibrio species starvation response, to affect biofilm formation in Vibrio anguillarum, Vibrio vulnificus and Vibrio cholerae, to reduce pigment and protease production in V. anguillarum, and to protect gnotobiotic Artemia from V. harveyi-induced mortality.

  7. Emitter formation in dendritic web silicon solar cells

    NASA Technical Reports Server (NTRS)

    Meier, D. L.; Rohatgi, A.; Campbell, R. B.; Alexander, P.; Fonash, S. J.; Singh, R.

    1984-01-01

    The use of liquid dopants and liquid masks for p-n junction formation in dendritic web solar cells was investigated and found to be equivalent to the use of gaseous dopants and CVD SiO2 masks previously used. This results in a projected cost reduction of 0.02 1980$/Watt for a 25 MW/year production line, and makes possible junction formation processes having a higher throughput than more conventional processes. The effect of a low-energy (0.4 keV) hydrogen ion implant on dendritic web solar cells was also investigated. Such an implant was observed to improve Voc and Jsc substantially. Measurements of internal quantum efficiency suggest that it is the base of the cell, rather than the emitter, which benefits from the hydrogen implant. The diffusion length for electrons in the p-type base increased from 53 microns to 150 microns in one case, with dendritic web cell efficiency being boosted to 15.2 percent. The mechanism by which low-energy hydrogen ions can penetrate deeply into the silicon to effect the observed improvement is not known at this time.

  8. Polyphenols action against oxidative stress formation in endothelial cells.

    PubMed

    Łuczaj, Wojciech; Zapora, Ewa; Szczepański, Marek; Wnuczko, Krzysztof; Skrzydlewska, Elzbieta

    2009-01-01

    The aim of this study was to investigate the influence of epigallocatechin-3-gallate (EGCG), theaflavins (TFs) and black tea extract (BTE) on oxidative stress formation as well as on antioxidant system of human vein endothelial cells (HUVEC). HUVEC were incubated for 0,5 h with 100 mM tert-butyl hydroperoxide (t-BHP) for oxidative stress formation. The influence of EGCG, TFs, and BTE on oxidative stress and antioxidant system parameters was investigated by the pre-incubation for 2 h with 50 mg/mL of each compound. Half hour exposure to t-BHP caused statistically significant decrease in GSH-Px activity and in the content of GSH, vitamin A, vitamin E as well as tryptophan. Moreover, pretreatment of cells with t-BHP caused statistically significant increase in activities of Cu,Zn-SOD, GSSG-R and in the level of MDA and dityrosine. Pretreated with t-BHP endothelial cells, subjected to EGCG, TFs and black tea extract, are partially protected against oxidative activity of t-BHP causing statistically significant increase in GSH-Px activity, GSH and tryptophan level and decrease in MDA and dityrosine level in comparison with HUVEC pretreated with t-BHP group. These results indicate the beneficial effect of tea polyphenolic compounds on HUVEC antioxidant abilities and, in consequence, their protective effect in cell components.

  9. FAM83H and casein kinase I regulate the organization of the keratin cytoskeleton and formation of desmosomes

    PubMed Central

    Kuga, Takahisa; Sasaki, Mitsuho; Mikami, Toshinari; Miake, Yasuo; Adachi, Jun; Shimizu, Maiko; Saito, Youhei; Koura, Minako; Takeda, Yasunori; Matsuda, Junichiro; Tomonaga, Takeshi; Nakayama, Yuji

    2016-01-01

    FAM83H is essential for the formation of dental enamel because a mutation in the FAM83H gene causes amelogenesis imperfecta (AI). We previously reported that the overexpression of FAM83H often occurs and disorganizes the keratin cytoskeleton in colorectal cancer cells. We herein show that FAM83H regulates the organization of the keratin cytoskeleton and maintains the formation of desmosomes in ameloblastoma cells. FAM83H is expressed and localized on keratin filaments in human ameloblastoma cell lines and in mouse ameloblasts and epidermal germinative cells in vivo. FAM83H shows preferential localization to keratin filaments around the nucleus that often extend to cell-cell junctions. Alterations in the function of FAM83H by its overexpression, knockdown, or an AI-causing truncated mutant prevent the proper organization of the keratin cytoskeleton in ameloblastoma cells. Furthermore, the AI-causing mutant prevents desmosomal proteins from being localized to cell-cell junctions. The effects of the AI-causing mutant depend on its binding to and possible inhibition of casein kinase I (CK-1). The suppression of CK-1 by its inhibitor, D4476, disorganizes the keratin cytoskeleton. Our results suggest that AI caused by the FAM83H mutation is mediated by the disorganization of the keratin cytoskeleton and subsequent disruption of desmosomes in ameloblasts. PMID:27222304

  10. Analysis of AIS Data of the Recluse Oil Field, Recluse, Wyoming

    NASA Technical Reports Server (NTRS)

    Dykstra, J. D.; Segal, D. B.

    1985-01-01

    Airborne Imaging Spectrometer (AIS) data were flown over the Recluse, Wyoming oil field on September 9, 1984. Processing software was developed at Earth Satellite Corporation (EarthSat) for interactive analysis of the AIS data. EarthSat's AIS processing capabilities include destriping, solar irradiance corrections, residual calculations, geometric resampling, equal energy normalization, interactive spectral classifications and a variety of compressive algorithms to reduce the data to 8-bit format with a minimum of information loss. The in-house photolab facilities of EarthSat can routinely produce high-quality color renditions of the enhanced AIS data. A total of 80 lithologic samples were collected under the AIS flight lines. Correlation (within the atmospheric windows) between the laboratory and the AIS spectra of sample sites was generally poor. Reasonable correlation was only possible in large, freshly plowed fields. Mixed pixels and contrast between the natural and sample's surfaces were believed responsible for the poor correlation. Finally, a drift of approximately three channels was observed in the diffraction grating position within the 1.8 to 2.1 micron quadrant.

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

    PubMed

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

    2012-01-01

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

  12. Schwann Cells in Neuromuscular Junction Formation and Maintenance

    PubMed Central

    Barik, Arnab; Li, Lei; Sathyamurthy, Anupama; Xiong, Wen-Cheng

    2016-01-01

    The neuromuscular junction (NMJ) is a tripartite synapse that is formed by motor nerve terminals, postjunctional muscle membranes, and terminal Schwann cells (TSCs) that cover the nerve-muscle contact. NMJ formation requires intimate communications among the three different components. Unlike nerve-muscle interaction, which has been well characterized, less is known about the role of SCs in NMJ formation and maintenance. We show that SCs in mice lead nerve terminals to prepatterned AChRs. Ablating SCs at E8.5 (i.e., prior nerve arrival at the clusters) had little effect on aneural AChR clusters at E13.5, suggesting that SCs may not be necessary for aneural clusters. SC ablation at E12.5, a time when phrenic nerves approach muscle fibers, resulted in smaller and fewer nerve-induced AChR clusters; however, SC ablation at E15.5 reduced AChR cluster size but had no effect on cluster density, suggesting that SCs are involved in AChR cluster maturation. Miniature endplate potential amplitude, but not frequency, was reduced when SCs were ablated at E15.5, suggesting that postsynaptic alterations may occur ahead of presynaptic deficits. Finally, ablation of SCs at P30, after NMJ maturation, led to NMJ fragmentation and neuromuscular transmission deficits. Miniature endplate potential amplitude was reduced 3 d after SC ablation, but both amplitude and frequency were reduced 6 d after. Together, these results indicate that SCs are not only required for NMJ formation, but also necessary for its maintenance; and postsynaptic function and structure appeared to be more sensitive to SC ablation. SIGNIFICANCE STATEMENT Neuromuscular junctions (NMJs) are critical for survival and daily functioning. Defects in NMJ formation during development or maintenance in adulthood result in debilitating neuromuscular disorders. The role of Schwann cells (SCs) in NMJ formation and maintenance was not well understood. We genetically ablated SCs during development and after NMJ formation to

  13. Biological surface engineering: a simple system for cell pattern formation.

    PubMed

    Zhang, S; Yan, L; Altman, M; Lässle, M; Nugent, H; Frankel, F; Lauffenburger, D A; Whitesides, G M; Rich, A

    1999-07-01

    Biological surface engineering using synthetic biological materials has a great potential for advances in our understanding of complex biological phenomena. We developed a simple system to engineer biologically relevant surfaces using a combination of self-assembling oligopeptide monolayers and microcontact printing (muCP). We designed and synthesized two oligopeptides containing a cell adhesion motif (RADS)n (n = 2 and 3) at the N-terminus, followed by an oligo(alanine) linker and a cysteine residue at the C-terminus. The thiol group of cysteine allows the oligopeptides to attach covalently onto a gold-coated surface to form monolayers. We then microfabricated a variety of surface patterns using the cell adhesion peptides in combination with hexa-ethylene glycol thiolate which resist non-specific adsorption of proteins and cells. The resulting patterns consist of areas either supporting or inhibiting cell adhesion, thus they are capable of aligning cells in a well-defined manner, leading to specific cell array and pattern formations.

  14. Acyl homoserine lactone-based quorum sensing stimulates biofilm formation by Salmonella Enteritidis in anaerobic conditions.

    PubMed

    Almeida, Felipe Alves de; Pimentel-Filho, Natan de Jesus; Pinto, Uelinton Manoel; Mantovani, Hilário Cuquetto; Oliveira, Leandro Licursi de; Vanetti, Maria Cristina Dantas

    2017-04-01

    Quorum sensing regulates a variety of phenotypes in bacteria including the production of virulence factors. Salmonella spp. have quorum sensing systems mediated by three autoinducers (AI-1, AI-2, and AI-3). The AI-1-mediated system is incomplete in that the bacterium relies on the synthesis of signaling molecules by other microorganisms. This study aimed to evaluate the influence of the AI-1 N-dodecanoyl-DL-homoserine lactone (C12-HSL) on the growth, motility, adhesion, and biofilm formation of Salmonella enterica serovar Enteritidis PT4 578 on a polystyrene surface. Experiments were conducted at 37 °C in anaerobic tryptone soy broth supplemented with C12-HSL and/or a mixture of four synthetic furanones, at the concentration of 50 nM each. The planktonic growth, adhesion, swarming, and twitching motility were not altered in the presence of C12-HSL and/or furanones under anaerobic conditions. However, C12-HSL induced biofilm formation after 36 h of cultivation as determined by quantification of biofilm formation, by enumeration of adhered cells to polystyrene coupons, and finally by imaging the presence of multilayered cells on an epifluorescence microscope. When furanones were present in the medium, an antagonistic effect against C12-HSL on the biofilm development was observed. The results demonstrate an induction of biofilm formation in Salmonella Enteritidis by AI-1 under anaerobic conditions. Considering that Salmonella does not produce AI-1 but respond to it, C12-HSL synthesized by other bacterial species could trigger biofilm formation by this pathogen in conditions that are relevant for its pathogenesis.

  15. Cell collectivity regulation within migrating cell cluster during Kupffer's vesicle formation in zebrafish

    PubMed Central

    Matsui, Takaaki; Ishikawa, Hiroshi; Bessho, Yasumasa

    2015-01-01

    Although cell adhesion is thought to fasten cells tightly, cells that adhere to each other can migrate directionally. This group behavior, called “collective cell migration,” is observed during normal development, wound healing, and cancer invasion. Loss-of-function of cell adhesion molecules in several model systems of collective cell migration results in delay or inhibition of migration of cell groups but does not lead to dissociation of the cell groups, suggesting that mechanisms of cells staying assembled as a single cell cluster, termed as “cell collectivity,” remain largely unknown. During the formation of Kupffer's vesicle (KV, an organ of laterality in zebrafish), KV progenitors form a cluster and migrate together toward the vegetal pole. Importantly, in this model system of collective cell migration, knockdown of cell adhesion molecules or signal components leads to failure of cell collectivity. In this review, we summarize recent findings in cell collectivity regulation during collective migration of KV progenitor cells and describe our current understanding of how cell collectivity is regulated during collective cell migration. PMID:26000276

  16. A microfluidic direct formate fuel cell on paper.

    PubMed

    Copenhaver, Thomas S; Purohit, Krutarth H; Domalaon, Kryls; Pham, Linda; Burgess, Brianna J; Manorothkul, Natalie; Galvan, Vicente; Sotez, Samantha; Gomez, Frank A; Haan, John L

    2015-08-01

    We describe the first direct formate fuel cell on a paper microfluidic platform. In traditional membrane-less microfluidic fuel cells (MFCs), external pumping consumes power produced by the fuel cell in order to maintain co-laminar flow of the anode stream and oxidant stream to prevent mixing. However, in paper microfluidics, capillary action drives flow while minimizing stream mixing. In this work, we demonstrate a paper MFC that uses formate and hydrogen peroxide as the anode fuel and cathode oxidant, respectively. Using these materials we achieve a maximum power density of nearly 2.5 mW/mg Pd. In a series configuration, our MFC achieves an open circuit voltage just over 1 V, and in a parallel configuration, short circuit of 20 mA absolute current. We also demonstrate that the MFC does not require continuous flow of fuel and oxidant to produce power. We found that we can pre-saturate the materials on the paper, stop the electrolyte flow, and still produce approximately 0.5 V for 15 min. This type of paper MFC has potential applications in point-of-care diagnostic devices and other electrochemical sensors.

  17. Graphene-Induced Pore Formation on Cell Membranes

    PubMed Central

    Duan, Guangxin; Zhang, Yuanzhao; Luan, Binquan; Weber, Jeffrey K.; Zhou, Royce W.; Yang, Zaixing; Zhao, Lin; Xu, Jiaying; Luo, Judong; Zhou, Ruhong

    2017-01-01

    Examining interactions between nanomaterials and cell membranes can expose underlying mechanisms of nanomaterial cytotoxicity and guide the design of safer nanomedical technologies. Recently, graphene has been shown to exhibit potential toxicity to cells; however, the molecular processes driving its lethal properties have yet to be fully characterized. We here demonstrate that graphene nanosheets (both pristine and oxidized) can produce holes (pores) in the membranes of A549 and Raw264.7 cells, substantially reducing cell viability. Electron micrographs offer clear evidence of pores created on cell membranes. Our molecular dynamics simulations reveal that multiple graphene nanosheets can cooperate to extract large numbers of phospholipids from the membrane bilayer. Strong dispersion interactions between graphene and lipid-tail carbons result in greatly depleted lipid density within confined regions of the membrane, ultimately leading to the formation of water-permeable pores. This cooperative lipid extraction mechanism for membrane perforation represents another distinct process that contributes to the molecular basis of graphene cytotoxicity. PMID:28218295

  18. Notch1-Dll4 signalling and mechanical force regulate leader cell formation during collective cell migration.

    PubMed

    Riahi, Reza; Sun, Jian; Wang, Shue; Long, Min; Zhang, Donna D; Wong, Pak Kin

    2015-03-13

    At the onset of collective cell migration, a subset of cells within an initially homogenous population acquires a distinct 'leader' phenotype with characteristic morphology and motility. However, the factors driving the leader cell formation as well as the mechanisms regulating leader cell density during the migration process remain to be determined. Here we use single-cell gene expression analysis and computational modelling to show that the leader cell identity is dynamically regulated by Dll4 signalling through both Notch1 and cellular stress in a migrating epithelium. Time-lapse microscopy reveals that Dll4 is induced in leader cells after the creation of the cell-free region and leader cells are regulated via Notch1-Dll4 lateral inhibition. Furthermore, mechanical stress inhibits Dll4 expression and leader cell formation in the monolayer. Collectively, our findings suggest that a reduction of mechanical force near the boundary promotes Notch1-Dll4 signalling to dynamically regulate the density of leader cells during collective cell migration.

  19. Notch1-Dll4 signaling and mechanical force regulate leader cell formation during collective cell migration

    PubMed Central

    Riahi, Reza; Sun, Jian; Wang, Shue; Long, Min; Zhang, Donna D.; Wong, Pak Kin

    2015-01-01

    At the onset of collective cell migration, a subset of cells within an initially homogenous population acquires a distinct “leader” phenotype with characteristic morphology and motility. However, the factors driving leader cell formation as well as the mechanisms regulating leader cell density during the migration process remain to be determined. Here, we use single cell gene expression analysis and computational modeling to show that leader cell identity is dynamically regulated by Dll4 signaling through both Notch1 and cellular stress in a migrating epithelium. Time-lapse microscopy reveals that Dll4 is induced in leader cells after the creation of the cell-free region and leader cells are regulated via Notch1-Dll4 lateral inhibition. Furthermore, mechanical stress inhibits Dll4 expression and leader cell formation in the monolayer. Collectively, our findings suggest that a reduction of mechanical force near the boundary promotes Notch1-Dll4 signaling to dynamically regulate the density of leader cells during collective cell migration. PMID:25766473

  20. Formation of nanofilms on cell surfaces to improve the insertion efficiency of a nanoneedle into cells

    SciTech Connect

    Amemiya, Yosuke; Kawano, Keiko; Matsusaki, Michiya; Akashi, Mitsuru; Nakamura, Noriyuki; Nakamura, Chikashi

    2012-04-13

    Highlights: Black-Right-Pointing-Pointer We examined the insertion efficiency of nanoneedles into fibroblast and neural cells. Black-Right-Pointing-Pointer Nanofilms formed on cell surfaces improved the insertion efficiency of nanoneedles. Black-Right-Pointing-Pointer Nanofilms improved the insertion efficiency even in Y27632-treated cells. -- Abstract: A nanoneedle, an atomic force microscope (AFM) tip etched to 200 nm in diameter and 10 {mu}m in length, can be inserted into cells with the aid of an AFM and has been used to introduce functional molecules into cells and to analyze intracellular information with minimal cell damage. However, some cell lines have shown low insertion efficiency of the nanoneedle. Improvement in the insertion efficiency of a nanoneedle into such cells is a significant issue for nanoneedle-based cell manipulation and analysis. Here, we have formed nanofilms composed of extracellular matrix molecules on cell surfaces and found that the formation of the nanofilms improved insertion efficiency of a nanoneedle into fibroblast and neural cells. The nanofilms were shown to improve insertion efficiency even in cells in which the formation of actin stress fibers was inhibited by the ROCK inhibitor Y27632, suggesting that the nanofilms with the mesh structure directly contributed to the improved insertion efficiency of a nanoneedle.

  1. Fabric-based alkaline direct formate microfluidic fuel cells.

    PubMed

    Domalaon, Kryls; Tang, Catherine; Mendez, Alex; Bernal, Franky; Purohit, Krutarth; Pham, Linda; Haan, John; Gomez, Frank A

    2017-01-12

    Fabric-based microfluidic fuel cells (MFCs) serve as a novel, cost-efficient alternative to traditional FCs and batteries, since fluids naturally travel across fabric via capillary action, eliminating the need for an external pump and lowering production and operation costs. Building on previous research with Y-shaped paper-based MFCs, fabric-based MFCs mitigate fragility and durability issues caused by long periods of fuel immersion. In this study, we describe a microfluidic fabric-based direct formate fuel cell, with 5 M potassium formate and 30% hydrogen peroxide as the anode fuel and cathode oxidant, respectively. Using a two-strip, stacked design, the optimized parameters include the type of encasement, the barrier, and the fabric type. Surface contact of the fabric and laminate sheet expedited flow and respective chemical reactions. The maximum current (22.83 mA/cm(2) ) and power (4.40 mW/cm(2) ) densities achieved with a 65% cotton/35% polyester blend material are a respective 8.7% and 32% higher than previous studies with Y-shaped paper-based MFCs. In series configuration, the MFCs generate sufficient energy to power a handheld calculator, a thermometer, and a spectrum of light-emitting diodes.

  2. Segrosome Complex Formation during DNA Trafficking in Bacterial Cell Division.

    PubMed

    Oliva, María A

    2016-01-01

    Bacterial extrachromosomal DNAs often contribute to virulence in pathogenic organisms or facilitate adaptation to particular environments. The transmission of genetic information from one generation to the next requires sufficient partitioning of DNA molecules to ensure that at least one copy reaches each side of the division plane and is inherited by the daughter cells. Segregation of the bacterial chromosome occurs during or after replication and probably involves a strategy in which several protein complexes participate to modify the folding pattern and distribution first of the origin domain and then of the rest of the chromosome. Low-copy number plasmids rely on specialized partitioning systems, which in some cases use a mechanism that show striking similarity to eukaryotic DNA segregation. Overall, there have been multiple systems implicated in the dynamic transport of DNA cargo to a new cellular position during the cell cycle but most seem to share a common initial DNA partitioning step, involving the formation of a nucleoprotein complex called the segrosome. The particular features and complex topologies of individual segrosomes depend on both the nature of the DNA binding protein involved and on the recognized centromeric DNA sequence, both of which vary across systems. The combination of in vivo and in vitro approaches, with structural biology has significantly furthered our understanding of the mechanisms underlying DNA trafficking in bacteria. Here, I discuss recent advances and the molecular details of the DNA segregation machinery, focusing on the formation of the segrosome complex.

  3. [To the history of Tretiyakov almshouse of the A.I. Vishnevskiy Institute of Surgery].

    PubMed

    Kuzybayeva, M P

    2014-01-01

    The article deals with reconstruction of history of building and functioning of Tretiyakov almshouse in the A.I. Vishnevskiy institute of surgery. The archive documents were used for exploration. The input of architect S.I. Soloviyev into formation of architectural complex is demonstrated. The significance of this object in the history of national architecture is established.

  4. Cadmium stimulates osteoclast-like multinucleated cell formation in mouse bone marrow cell cultures

    SciTech Connect

    Miyahara, Tatsuro; Takata, Masakazu; Miyata, Masaki; Nagai, Miyuki; Sugure, Akemi; Kozuka, Hiroshi; Kuze, Shougo )

    1991-08-01

    Most of cadmium (Cd)-treated animals have been reported to show osteoporosis-like changes in bones. This suggests that Cd may promote bone loss by a direct action on bone. It was found that Cd stimulated prostaglandin E{sub 2}(PGE{sub 2}) production in the osteoblast-like cell, MC3T3-E1. Therefore, Cd stimulates bone resorption by increasing PGE{sub 2} production. Recently, several bone marrow cell culture systems have been developed for examining the formation of osteoclast-like multinucleated cells in vitro. As osteoblasts produce PGE{sub 2} by Cd-induced cyclooxygenase and may play an important role in osteoclast formation, the present study was undertaken to clarify the possibility that Cd might stimulate osteoclast formation in a mouse bone marrow culture system.

  5. Arsenic promotes centrosome abnormalities and cell colony formation in p53 compromised human lung cells

    SciTech Connect

    Liao Weiting; Lin Pinpin; Cheng, T.-S.; Yu, H.-S.; Chang, Louis W.

    2007-12-01

    Epidemiological evidence indicated that residents, especially cigarette smokers, in arseniasis areas had significantly higher lung cancer risk than those living in non-arseniasis areas. Thus, an interaction between arsenic and cigarette smoking in lung carcinogenesis was suspected. p53 dysfunction or mutation in lung epithelial cells was frequently observed in cigarette smokers. Our present study was to explore the differential effects by arsenic on H1355 cells (human lung adenocarcinoma cell line with mutation in p53), BEAS-2B (immortalized lung epithelial cell with functional p53) and pifithrin-{alpha}-treated BEAS-2B cells (p53-inhibited cells). These cells were treated with different doses of sodium arsenite (0, 0.1, 1, 5 and 10 {mu}M) for 48 h. A greater reduction in cell viability was observed in the BEAS-2B cells vs. p53 compromised cells (H1355 or p53-inhibited BEAS-2B). Similar observation was also made on 7-day cell survival (growth) study. TUNEL analysis confirmed that there was indeed a significantly reduced arsenite-induced apoptosis found in p53-compromised cells. Centrosomal abnormality has been attributed to eventual chromosomal missegregation, aneuploidy and tumorigenesis. In our present study, reduced p21 and Gadd45a expressions and increased centrosomal abnormality (atopic and multiple centrosomes) were observed in both arsenite-treated H1355 and p53-inhibited BEAS-2B cells as compared with similarly treated BEAS-2B cells. Increased anchorage-independent growth (colony formation) of BEAS-2B cells co-treated with pifithrin-{alpha} and 5 {mu}M sodium arsenite was also observed in soft agar. Our present investigation demonstrated that arsenic would act specifically on p53 compromised cells (either with p53 dysfunction or inhibited) to induce centrosomal abnormality and colony formation. These findings provided strong evidence on the carcinogenic promotional role of arsenic, especially under the condition of p53 dysfunction.

  6. DNA microarray analysis reveals crosstalk of Salmonella enterica serovar Typhimurium with AI-2 of Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quorum sensing, or cell-to-cell communication, is made possible by the production and sensing of small, extracellular chemical signals called autoinducers (AI). These autoinducers accumulate as the population density increases, and thereby help bacteria to regulate their behavior by promoting or rep...

  7. Aurora kinase A and B as new treatment targets in aromatase inhibitor-resistant breast cancer cells.

    PubMed

    Hole, Stine; Pedersen, Astrid M; Lykkesfeldt, Anne E; Yde, Christina W

    2015-02-01

    Aromatase inhibitors (AIs) are used for treatment of estrogen receptor α (ER)-positive breast cancer; however, resistance is a major obstacle for optimal outcome. This preclinical study aimed at identifying potential new treatment targets in AI-resistant breast cancer cells. Parental MCF-7 breast cancer cells and four newly established cell lines, resistant to the AIs exemestane or letrozole, were used for a functional kinase inhibitor screen. A library comprising 195 different compounds was tested for preferential growth inhibition of AI-resistant cell lines. Selected targets were validated by analysis of cell growth, cell cycle phase distribution, protein expression, and subcellular localization. We identified 24 compounds, including several inhibitors of Aurora kinases e.g., JNJ-7706621 and barasertib. Protein expression of Aurora kinase A and B was found upregulated in AI-resistant cells compared with MCF-7, and knockdown studies showed that Aurora kinase A was essential for AI-resistant cell growth. In AI-resistant cell lines, the clinically relevant Aurora kinase inhibitors alisertib and danusertib blocked cell cycle progression at the G2/M phase, interfered with chromosome alignment and spindle pole formation, and resulted in preferential growth inhibition compared with parental MCF-7 cells. Even further growth inhibition was obtained when combining the Aurora kinase inhibitors with the antiestrogen fulvestrant. Our study is the first to demonstrate that Aurora kinase A and B may be treatment targets in AI-resistant cells, and our data suggest that therapy targeting both ER and Aurora kinases may be a potent treatment strategy for overcoming AI resistance in breast cancer.

  8. Effect of salinity and incubation time of planktonic cells on biofilm formation, motility, exoprotease production, and quorum sensing of Aeromonas hydrophila.

    PubMed

    Jahid, Iqbal Kabir; Mizan, Md Furkanur Rahaman; Ha, Angela J; Ha, Sang-Do

    2015-08-01

    The aim of this study was to determine the effect of salinity and age of cultures on quorum sensing, exoprotease production, and biofilm formation by Aeromonas hydrophila on stainless steel (SS) and crab shell as substrates. Biofilm formation was assessed at various salinities, from fresh (0%) to saline water (3.0%). For young and old cultures, planktonic cells were grown at 30 °C for 24 h and 96 h, respectively. Biofilm formation was assessed on SS, glass, and crab shell; viable counts were determined in R2A agar for SS and glass, but Aeromonas-selective media was used for crab shell samples to eliminate bacterial contamination. Exoprotease activity was assessed using a Fluoro™ protease assay kit. Quantification of acyl-homoserine lactone (AHL) was performed using the bioreporter strain Chromobacterium violaceum CV026 and the concentration was confirmed using high-performance liquid chromatography (HPLC). The concentration of autoinducer-2 (AI-2) was determined with Vibrio harveyi BB170. The biofilm structure at various salinities (0-3 %) was assessed using field emission electron microscopy (FESEM). Young cultures of A. hydrophila grown at 0-0.25% salinity showed gradual increasing of biofilm formation on SS, glass and crab shell; swarming and swimming motility; exoproteases production, AHL and AI-2 quorum sensing; while all these phenotypic characters reduced from 0.5 to 3.0% salinity. The FESEM images also showed that from 0 to 0.25% salinity stimulated formation of three-dimensional biofilm structures that also broke through the surface by utilizing the chitin surfaces of crab, while 3% salinity stimulated attachment only for young cultures. However, in marked contrast, salinity (0.1-3%) had no effect on the stimulation of biofilm formation or on phenotypic characters for old cultures. However, all concentrations reduced biofilm formation, motility, protease production and quorum sensing for old culture. Overall, 0-0.25% salinity enhanced biofilm formation

  9. AI in space: Past, present, and possible futures

    NASA Technical Reports Server (NTRS)

    Rose, Donald D.; Post, Jonathan V.

    1992-01-01

    While artificial intelligence (AI) has become increasingly present in recent space applications, new missions being planned will require even more incorporation of AI techniques. In this paper, we survey some of the progress made to date in implementing such programs, some current directions and issues, and speculate about the future of AI in space scenarios. We also provide examples of how thinkers from the realm of science fiction have envisioned AI's role in various aspects of space exploration.

  10. Deploying Embodied AI into Virtual Worlds

    NASA Astrophysics Data System (ADS)

    Burden, David J. H.

    The last two years have seen the start of commercial activity within virtual worlds. Unlike computer games where Non-Player-Character avatars are common, in most virtual worlds they are the exception — and until recently in Second Life they were non-existent. However there is real commercial scope for Als in these worlds — in roles from virtual sales staff and tutors to personal assistants. Deploying an embodied AI into a virtual world offers a unique opportunity to evaluate embodied Als, and to develop them within an environment where human and computer are on almost equal terms. This paper presents an architecture being used for the deployment of chatbot driven avatars within the Second Life virtual world, looks at the challenges of deploying an AI within such a virtual world, the possible implications for the Turing Test, and identifies research directions for the future.

  11. Why Don't Accounting Students like AIS?

    ERIC Educational Resources Information Center

    Vatanasakdakul, Savanid; Aoun, Chadi

    2011-01-01

    Purpose: The demand for Accounting Information Systems (AIS) knowledge has increased exponentially over the past two decades, but studying AIS has not proved easy for many accounting students. The aim of the study is to understand the challenges accounting students face in studying AIS through investigation of the factors which may be contributing…

  12. The AI Interdisciplinary Context: Single or Multiple Research Bases?

    ERIC Educational Resources Information Center

    Khawam, Yves J.

    1992-01-01

    This study used citation analysis to determine whether the disciplines contributing to the journal literature of artificial intelligence (AI)--philosophy, psychology, linguistics, computer science, and engineering--share a common AI research base. The idea that AI consists of a completely interdisciplinary endeavor was refuted. (MES)

  13. 47 CFR 80.393 - Frequencies for AIS stations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Frequencies for AIS stations. 80.393 Section 80.393 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Ais Stations § 80.393 Frequencies for AIS stations....

  14. Tactical AI in Real Time Strategy Games

    DTIC Science & Technology

    2015-03-26

    evolutionary algorithms (MOEAs) in this tactical decision making problem allows an AI agent to make fast , effective solutions that do not require modification...ranged attacks. The terran army operates most similarly to Warcraft. The player must still balance food (supply depots), and two other resources (minerals...types of methods analyze the current status of enemy units and makes a decision based on a single metric. These techniques are very fast , but are open to

  15. Diclofenac in Arabidopsis cells: Rapid formation of conjugates.

    PubMed

    Fu, Qiuguo; Ye, Qingfu; Zhang, Jianbo; Richards, Jaben; Borchardt, Dan; Gan, Jay

    2017-03-01

    Pharmaceutical and personal care products (PPCPs) are continuously introduced into the soil-plant system, through practices such as agronomic use of reclaimed water and biosolids containing these trace contaminants. Plants may accumulate PPCPs from soil, serving as a conduit for human exposure. Metabolism likely controls the final accumulation of PPCPs in plants, but is in general poorly understood for emerging contaminants. In this study, we used diclofenac as a model compound, and employed (14)C tracing, and time-of-flight (TOF) and triple quadruple (QqQ) mass spectrometers to unravel its metabolism pathways in Arabidopsis thaliana cells. We further validated the primary metabolites in Arabidopsis seedlings. Diclofenac was quickly taken up into A. thaliana cells. Phase I metabolism involved hydroxylation and successive oxidation and cyclization reactions. However, Phase I metabolites did not accumulate appreciably; they were instead rapidly conjugated with sulfate, glucose, and glutamic acid through Phase II metabolism. In particular, diclofenac parent was directly conjugated with glutamic acid, with acyl-glutamatyl-diclofenac accounting for >70% of the extractable metabolites after 120-h incubation. In addition, at the end of incubation, >40% of the spiked diclofenac was in the non-extractable form, suggesting extensive sequestration into cell matter. The rapid formation of non-extractable residue and dominance of diclofenac-glutamate conjugate uncover previously unknown metabolism pathways for diclofenac. In particular, the rapid conjugation of parent highlights the need to consider conjugates of emerging contaminants in higher plants, and their biological activity and human health implications.

  16. Mechanical roles of apical constriction, cell elongation, and cell migration during neural tube formation in Xenopus.

    PubMed

    Inoue, Yasuhiro; Suzuki, Makoto; Watanabe, Tadashi; Yasue, Naoko; Tateo, Itsuki; Adachi, Taiji; Ueno, Naoto

    2016-12-01

    Neural tube closure is an important and necessary process during the development of the central nervous system. The formation of the neural tube structure from a flat sheet of neural epithelium requires several cell morphogenetic events and tissue dynamics to account for the mechanics of tissue deformation. Cell elongation changes cuboidal cells into columnar cells, and apical constriction then causes them to adopt apically narrow, wedge-like shapes. In addition, the neural plate in Xenopus is stratified, and the non-neural cells in the deep layer (deep cells) pull the overlying superficial cells, eventually bringing the two layers of cells to the midline. Thus, neural tube closure appears to be a complex event in which these three physical events are considered to play key mechanical roles. To test whether these three physical events are mechanically sufficient to drive neural tube formation, we employed a three-dimensional vertex model and used it to simulate the process of neural tube closure. The results suggest that apical constriction cued the bending of the neural plate by pursing the circumference of the apical surface of the neural cells. Neural cell elongation in concert with apical constriction further narrowed the apical surface of the cells and drove the rapid folding of the neural plate, but was insufficient for complete neural tube closure. Migration of the deep cells provided the additional tissue deformation necessary for closure. To validate the model, apical constriction and cell elongation were inhibited in Xenopus laevis embryos. The resulting cell and tissue shapes resembled the corresponding simulation results.

  17. SDI satellite autonomy using AI and Ada

    NASA Technical Reports Server (NTRS)

    Fiala, Harvey E.

    1990-01-01

    The use of Artificial Intelligence (AI) and the programming language Ada to help a satellite recover from selected failures that could lead to mission failure are described. An unmanned satellite will have a separate AI subsystem running in parallel with the normal satellite subsystems. A satellite monitoring subsystem (SMS), under the control of a blackboard system, will continuously monitor selected satellite subsystems to become alert to any actual or potential problems. In the case of loss of communications with the earth or the home base, the satellite will go into a survival mode to reestablish communications with the earth. The use of an AI subsystem in this manner would have avoided the tragic loss of the two recent Soviet probes that were sent to investigate the planet Mars and its moons. The blackboard system works in conjunction with an SMS and a reconfiguration control subsystem (RCS). It can be shown to be an effective way for one central control subsystem to monitor and coordinate the activities and loads of many interacting subsystems that may or may not contain redundant and/or fault-tolerant elements. The blackboard system will be coded in Ada using tools such as the ABLE development system and the Ada Production system.

  18. ZO-1 controls endothelial adherens junctions, cell-cell tension, angiogenesis, and barrier formation.

    PubMed

    Tornavaca, Olga; Chia, Minghao; Dufton, Neil; Almagro, Lourdes Osuna; Conway, Daniel E; Randi, Anna M; Schwartz, Martin A; Matter, Karl; Balda, Maria S

    2015-03-16

    Intercellular junctions are crucial for mechanotransduction, but whether tight junctions contribute to the regulation of cell-cell tension and adherens junctions is unknown. Here, we demonstrate that the tight junction protein ZO-1 regulates tension acting on VE-cadherin-based adherens junctions, cell migration, and barrier formation of primary endothelial cells, as well as angiogenesis in vitro and in vivo. ZO-1 depletion led to tight junction disruption, redistribution of active myosin II from junctions to stress fibers, reduced tension on VE-cadherin and loss of junctional mechanotransducers such as vinculin and PAK2, and induced vinculin dissociation from the α-catenin-VE-cadherin complex. Claudin-5 depletion only mimicked ZO-1 effects on barrier formation, whereas the effects on mechanotransducers were rescued by inhibition of ROCK and phenocopied by JAM-A, JACOP, or p114RhoGEF down-regulation. ZO-1 was required for junctional recruitment of JACOP, which, in turn, recruited p114RhoGEF. ZO-1 is thus a central regulator of VE-cadherin-dependent endothelial junctions that orchestrates the spatial actomyosin organization, tuning cell-cell tension, migration, angiogenesis, and barrier formation.

  19. Carbon onions as nanoscopic pressure cells for diamond formation

    NASA Astrophysics Data System (ADS)

    Banhart, F.; Ajayan, P. M.

    1996-08-01

    SPHERICAL particles of carbon consisting of concentric graphite-like shells ('carbon onions') can be formed by electron irradiation of graphitic carbon materials1,2. Here we report that, when such particles are heated to ~700 °C and irradiated with electrons, their cores can be transformed to diamond. Under these conditions the spacing between layers in the carbon onions decreases from 0.31 in the outer shells (slightly less than the 0.34-nm layer spacing of graphite) to about 0.22 nm in the core, indicating considerable compression towards the particle centres. We find that this compression allows diamond to nucleate-in effect the carbon onions act as nanoscopic pressure cells for diamond formation.

  20. Light induced polaron formation in perovskite solar cell devices

    NASA Astrophysics Data System (ADS)

    Neukirch, Amanda; Nie, Wanyi; Blancon, Jean-Christophe; Appavoo, Kannatassen; Tsai, Hsinhan; Chhowalla, Manish; Alam, Muhammad; Sfeir, Matthew; Katan, Claudine; Even, Jacky; Crochet, Jared; Gupta, Gautum; Mohite, Aditya; Tretiak, Sergei

    The need for a low-cost, clean, and abundant source of energy has generated large amounts of research in solution processed solar cell materials. The lead halide perovskite has rapidly developed as a serious candidate for the active layer of photovoltaic devices. The efficiencies of devices made with this material have increased from 3.5% to over 20% in around 5 years. Despite the remarkable progress associated with perovskite materials, there are still fundamental questions regarding their lack of photo-stability over prolonged solar irradiation that need to be addressed. Recent experiments on photo-degradation under constant illumination have found fast self-healing by resting the device in the dark for less than 1 minute. Density functional theory and symmetry analysis show that localized charge states couple to local structural lattice distortions and methyl ammonium quasistatic configurations. Once translational symmetry is lost, additional bonding configurations become symmetry allowed, triggering localized charges in the vicinity over time under constant illumination, thus seeding the formation of macroscopic charged domains and preventing efficient charge extraction. Here we present an in-depth study of polaron formation and binding energy at the atomistic level.

  1. Membrane tether formation from outer hair cells with optical tweezers.

    PubMed Central

    Li, Zhiwei; Anvari, Bahman; Takashima, Masayoshi; Brecht, Peter; Torres, Jorge H; Brownell, William E

    2002-01-01

    Optical tweezers were used to characterize the mechanical properties of the outer hair cell (OHC) plasma membrane by pulling tethers with 4.5-microm polystyrene beads. Tether formation force and tether force were measured in static and dynamic conditions. A greater force was required for tether formations from OHC lateral wall (499 +/- 152 pN) than from OHC basal end (142 +/- 49 pN). The difference in the force required to pull tethers is consistent with an extensive cytoskeletal framework associated with the lateral wall known as the cortical lattice. The apparent plasma membrane stiffness, estimated under the static conditions by measuring tether force at different tether length, was 3.71 pN/microm for OHC lateral wall and 4.57 pN/microm for OHC basal end. The effective membrane viscosity was measured by pulling tethers at different rates while continuously recording the tether force, and estimated in the range of 2.39 to 5.25 pN x s/microm. The viscous force most likely results from the viscous interactions between plasma membrane lipids and the OHC cortical lattice and/or integral membrane proteins. The information these studies provide on the mechanical properties of the OHC lateral wall is important for understanding the mechanism of OHC electromotility. PMID:11867454

  2. An improved alkaline direct formate paper microfluidic fuel cell.

    PubMed

    Galvan, Vicente; Domalaon, Kryls; Tang, Catherine; Sotez, Samantha; Mendez, Alex; Jalali-Heravi, Mehdi; Purohit, Krutarth; Pham, Linda; Haan, John; Gomez, Frank A

    2016-02-01

    Paper-based microfluidic fuel cells (MFCs) are a potential replacement for traditional FCs and batteries due to their low cost, portability, and simplicity to operate. In MFCs, separate solutions of fuel and oxidant migrate through paper due to capillary action and laminar flow and, upon contact with each other and catalyst, produce electricity. In the present work, we describe an improved microfluidic paper-based direct formate FC (DFFC) employing formate and hydrogen peroxide as the anode fuel and cathode oxidant, respectively. The dimensions of the lateral column, current collectors, and cathode were optimized. A maximum power density of 2.53 mW/cm(2) was achieved with a DFFC of surface area 3.0 cm(2) , steel mesh as current collector, 5% carbon to paint mass ratio for cathode electrode and, 30% hydrogen peroxide. The longevity of the MFC's detailed herein is greater than eight hours with continuous flow of streams. In a series configuration, the MFCs generate sufficient energy to power light-emitting diodes and a handheld calculator.

  3. Functional definition of LuxS, an autoinducer-2 (AI-2) synthase and its role in full virulence of Streptococcus suis serotype 2.

    PubMed

    Cao, Min; Feng, Youjun; Wang, Changjun; Zheng, Feng; Li, Ming; Liao, Hui; Mao, Yinghua; Pan, Xiuzhen; Wang, Jing; Hu, Dan; Hu, Fuquan; Tang, Jiaqi

    2011-12-01

    Quorum sensing is a widespread chemical communication in response to fluctuation of bacterial population density, and has been implicated into bacterial biofilm formation and regulation of expression of virulence factors. The luxS gene product, S-ribosylhomocysteinase, catalizes the last committed step in biosynthetic pathway of autoinducer 2 (AI-2), a signaling molecule for inter-species quorum sensing. We found a luxS homologue in 05ZYH33, an epidemic strain of Streptococcus suis serotype 2 (SS2) in China. A luxS null mutant (ΔluxS) of 05ZYH33 strain was obtained using an approach of homologous recombination. LuxS was determined to be required for AI-2 production in 05ZYH33 strain of S. suis 2. Inactivation of luxS gene led to a wide range of phenotypic changes including thinner capsular walls, increased tolerance to H(2)O(2), reduced adherence capacity to epithelial cells, etc. In particular, loss of LuxS impaired dramatically its full virulence of SS2 in experimental model of piglets, and functional complementation restored it nearly to the level of parent strain. Genome-wide transcriptome analyses suggested that some known virulence factors such as CPS are down-regulated in the ΔluxS mutant, which might in part explain virulence attenuation by luxS deletion. Similarly, 29 of 71 genes with different expression level were proposed to be targets candidate regulated by LuxS/AI-2-dependent quorum sensing.

  4. Human germ cell formation in xenotransplants of induced pluripotent stem cells carrying X chromosome aneuploidies

    PubMed Central

    Dominguez, Antonia A.; Chiang, H. Rosaria; Sukhwani, Meena; Orwig, Kyle E.; Reijo Pera, Renee A.

    2014-01-01

    Turner syndrome is caused by complete or partial loss of the second sex chromosome and is characterized by spontaneous fetal loss in >90% of conceptions. Survivors possess an array of somatic and germline clinical characteristics. Induced pluripotent stem cells (iPSCs) offer an opportunity for insight into genetic requirements of the X chromosome linked to Turner syndrome. We derived iPSCs from Turner syndrome and control individuals and examined germ cell development as a function of X chromosome composition. We demonstrate that two X chromosomes are not necessary for reprogramming or maintenance of pluripotency and that there are minimal differences in gene expression, at the single cell level, linked to X chromosome aneuploidies. Formation of germ cells, as assessed in vivo through a murine xenotransplantation model, indicated that undifferentiated iPSCs, independent of X chromosome composition, are capable of forming germ-cell-like cells (GCLCs) in vivo. In combination with clinical data regarding infertility in women with X chromosome aneuploidies, results suggest that two intact X chromosomes are not required for human germ cell formation, qualitatively or quantitatively, but rather are likely to be required for maintenance of human germ cells to adulthood. PMID:25242416

  5. Human germ cell formation in xenotransplants of induced pluripotent stem cells carrying X chromosome aneuploidies.

    PubMed

    Dominguez, Antonia A; Chiang, H Rosaria; Sukhwani, Meena; Orwig, Kyle E; Reijo Pera, Renee A

    2014-09-22

    Turner syndrome is caused by complete or partial loss of the second sex chromosome and is characterized by spontaneous fetal loss in >90% of conceptions. Survivors possess an array of somatic and germline clinical characteristics. Induced pluripotent stem cells (iPSCs) offer an opportunity for insight into genetic requirements of the X chromosome linked to Turner syndrome. We derived iPSCs from Turner syndrome and control individuals and examined germ cell development as a function of X chromosome composition. We demonstrate that two X chromosomes are not necessary for reprogramming or maintenance of pluripotency and that there are minimal differences in gene expression, at the single cell level, linked to X chromosome aneuploidies. Formation of germ cells, as assessed in vivo through a murine xenotransplantation model, indicated that undifferentiated iPSCs, independent of X chromosome composition, are capable of forming germ-cell-like cells (GCLCs) in vivo. In combination with clinical data regarding infertility in women with X chromosome aneuploidies, results suggest that two intact X chromosomes are not required for human germ cell formation, qualitatively or quantitatively, but rather are likely to be required for maintenance of human germ cells to adulthood.

  6. Increased human hybridoma formation by electrofusion of human B cells with heteromyeloma SPAM-8 cells.

    PubMed

    Panova, I; Gustafsson, B

    1995-06-01

    A fusion protocol was designed for the optimal production of hybridomas following electrofusion of human B cells with cells of the heteromyeloma fusion partner SPAM-8. Peripheral blood lymphocytes showed an average fusion efficiency of 0.4 x 10(-4) whereas Epstein-Barr virus-transformed B cells showed fusion efficiencies ranging from 6.2 x 10(-4) to 9.0 x 10(-4). Similar results were obtained with bone marrow-derived lymphocytes. Trypsin treatment of the cells prior to electrofusion further increased the fusion efficiency to 12.3 x 10(-4). In comparison, conventional polyethylene glycol-induced fusion resulted in a fusion efficiency of 0.8 x 10(-4). Thus, electrofusion of human B cells with SPAM-8 heteromyeloma cells introduced a 15-fold increase in hybridoma formation as compared to the conventional fusion method.

  7. Myosin II-mediated cell shape changes and cell intercalation contribute to primitive streak formation

    PubMed Central

    Song, Feifei; Sang, Helen M.; Martin, René; Knölker, Hans-Joachim; MacDonald, Michael P; Weijer, Cornelis J

    2016-01-01

    Primitive streak formation in the chick embryo involves large scale highly coordinated flows of over 100.000 cells in the epiblast. These large scale tissue flows and deformations can be correlated with specific anisotropic cell behaviours in the forming mesendoderm through a combined light-sheet microscopy and computational analysis. Relevant behaviours include apical contraction, elongation along the apical-basal axis followed by ingression as well as asynchronous directional cell intercalation of small groups of mesendoderm cells. Cell intercalation is associated with sequential, directional contraction of apical junctions, the onset, localisation and direction of which correlate strongly with the appearance of active Myosin II cables in aligned apical junctions in neighbouring cells. Use of a class specific Myosin inhibitors and gene specific knockdowns show that apical contraction and intercalation are Myosin II dependent and also reveal critical roles for Myosin I and Myosin V family members in the assembly of junctional Myosin II cables. PMID:25812521

  8. Revisiting AI-2 quorum sensing inhibitors: direct comparison of alkyl-DPD analogues and a natural product fimbrolide.

    PubMed

    Lowery, Colin A; Abe, Takumi; Park, Junguk; Eubanks, Lisa M; Sawada, Daisuke; Kaufmann, Gunnar F; Janda, Kim D

    2009-11-04

    Quorum sensing (QS) systems have been discovered in a wide variety of bacteria, and mediate both intra- and interspecies communication. The AI-2-based QS system represents the most studied of these proposed interspecies systems and has been shown to regulate diverse functions such as bioluminescence, expression of virulence factors, and biofilm formation. As such, the development of modulatory compounds, both agonists and antagonists, is of great interest for the study of unknown AI-2-based QS systems and the potential treatment of bacterial infections. The fimbrolide class of natural products has exhibited excellent inhibitory activity against AI-2-based QS and as such may be considered the "gold standard" of AI-2 inhibitors. Thus, we sought to include a fimbrolide as a control compound for our recently developed alkyl-DPD panel of AI-2 modulators. Herein, we present a revised synthesis of a commonly studied fimbrolide as well as a direct comparison between the fimbrolide and alkyl-DPD analogues. We demonstrate that our alkyl-DPD analogues are more potent inhibitors of QS in both Vibrio harveyi and Salmonella typhimurium, the two organisms with defined AI-2 QS systems, and in doing so call into question the widely accepted use of fimbrolide-derived compounds as the "gold standard" of AI-2 inhibition.

  9. Cartilage formation in the CELLS 'double bubble' hardware

    NASA Technical Reports Server (NTRS)

    Duke, P. J.; Arizpe, Jorge; Montufar-Solis, Dina

    1991-01-01

    The CELLS experiment scheduled to be flown on the first International Microgravity Laboratory is designed to study the effect of microgravity on the cartilage formation, by measuring parameters of growth in a differentiating cartilage cell culture. This paper investigates the conditions for this experiment by studying cartilage differentiation in the 'bubble exchange' hardware with the 'double bubble' design in which the bubbles are joined by a flange which also overlays the gasket. Four types of double bubbles (or double gas permeable membranes) were tested: injection-molded bubbles 0.01- and 0.005-in. thick, and compression molded bubbles 0.015- and 0.01-in. thick. It was found that double bubble membranes of 0.005- and 0.010-in. thickness supported cartilage differentiation, while the 0.015-in. bubbles did not. It was also found that nodule count, used in this study as a parameter, is not the best measure of the amount of cartilage differentiation.

  10. Membrane electrolytic cell for minimizing hypochlorite and chlorate formation

    SciTech Connect

    Fair, D. L.; Justice, D. D.; Woodard Jr., K. E.

    1985-07-09

    An electrolytic cell for the electrolysis of an alkali metal chloride brine is comprised of an anode compartment and a cathode compartment separated by a cation exchange membrane. The anode is comprised of an unflattened expanded structure of a valve metal selected from the group consisting of titanium, tantalum, niobium, and alloys thereof. At least one side of the anode has as the electrochemically active surface an electrodeposited layer of a valve metal oxide. A plurality of cracks traverse the electrodeposited layer and a coating of a platinum metal group oxide covers the electrodeposited layer and substantially fills the cracks. The cationic exchange membrane is comprised of a laminated structure having a first surface adapted to contact an anolyte in which the ion exchange groups are predominately sulfonic acid groups. The first surface is also in contact with the electrochemically active surface of the anode. A second surface of the cation exchange membrane, adapted to contact a catholyte, has ion exchange groups which are predominately carboxylic acid groups. The cathode positioned in the cathode compartment is spaced apart from the cation exchange membrane. The cell operates with both a low chlorine overvoltage and a low oxygen overvoltage. During electrolysis of alkali metal chloride brines, the formation of hypochlorite and chlorate ions is minimized and the alkali metal hydroxides produced have low chlorate concentrations and are suitable for use without further treatment in chlorate-sensitive applications. Spent brine treatment is simplified and at reduced costs.

  11. Effect of cell-substratum interaction on hemicyst formation by MDCK cells.

    PubMed

    Rabito, C A; Tchao, R; Valentich, J; Leighton, J

    1980-06-01

    On impermeable substrata MDCK cells, a cell line derived from normal dog kidney, forms a confluent monolayer that is studded with numerous hemicysts. Previous studies with this cell line suggest that thes hemicysts develop as a result of active fluid accumulation between cell sheet and substratum. However, the formation of hemicysts as a multifocal phenomenon is still unexplained. The results presented here show that the hemicysts are not only expressions of active transport of solutes and water, but also of cell-substratum interaction. The increase in number and size of the hemicyst produced by dbcAMP may be explained by a decrease in the adhesive strength to substrata produced by this compound. Moreover, when the strength of the cell-substratum adhesion was increased the number of hemicysts was reduced or abolished. On the contrary, when this strength was reduced, larger hemicysts occurred, covering practically all the area available for growth. Results from cinematographic time lapse studies, showing that 90% of the area of the monolayer is able to produce hemicysts, also suggest that hemicyst formation as a multifocal phenomenon is more an expression of local variations in cell-substratum interaction than of regional changes in transepithelial active transport.

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

    PubMed

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

    2015-09-16

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

  13. Spheroid Formation of Hepatocarcinoma Cells in Microwells: Experiments and Monte Carlo Simulations

    PubMed Central

    Tabaei, Seyed R.; Park, Jae Hyeok; Na, Kyuhwan; Chung, Seok; Zhdanov, Vladimir P.

    2016-01-01

    The formation of spherical aggregates during the growth of cell population has long been observed under various conditions. We observed the formation of such aggregates during proliferation of Huh-7.5 cells, a human hepatocarcinoma cell line, in a microfabricated low-adhesion microwell system (SpheroFilm; formed of mass-producible silicone elastomer) on the length scales up to 500 μm. The cell proliferation was also tracked with immunofluorescence staining of F-actin and cell proliferation marker Ki-67. Meanwhile, our complementary 3D Monte Carlo simulations, taking cell diffusion and division, cell-cell and cell-scaffold adhesion, and gravity into account, illustrate the role of these factors in the formation of spheroids. Taken together, our experimental and simulation results provide an integrative view of the process of spheroid formation for Huh-7.5 cells. PMID:27571565

  14. Self-organization and advective transport in the cell polarity formation for asymmetric cell division.

    PubMed

    Seirin Lee, Sungrim; Shibata, Tatsuo

    2015-10-07

    Anterior-Posterior (AP) polarity formation of cell membrane proteins plays a crucial role in determining cell asymmetry, which depends not only on the several genetic process but also biochemical and biophysical interactions. The mechanism of AP formation of Caenorhabditis elegans embryo is characterized into the three processes: (i) membrane association and dissociation of posterior and anterior proteins, (ii) diffusion into the membrane and cytosol, and (iii) active cortical and cytoplasmic flows induced by the contraction of the acto-myosin cortex. We explored the mechanism of symmetry breaking and AP polarity formation using self-recruitment model of posterior proteins. We found that the AP polarity pattern is established over wide range in the total mass of polarity proteins and the diffusion ratio in the cytosol to the membrane. We also showed that the advective transport in both membrane and cytosol during the establishment phase affects optimal time interval of establishment and positioning of the posterior domain, and plays a role to increase the robustness in the AP polarity formation by reducing the number of posterior domains for the sensitivity of initial conditions. We also demonstrated that a proper ratio of the total mass to cell size robustly regulate the length scale of the posterior domain.

  15. In vivo differentiation of induced pluripotent stem cells into neural stem cells by chimera formation

    PubMed Central

    Choi, Hyun Woo; Hong, Yean Ju; Kim, Jong Soo; Song, Hyuk; Cho, Ssang Gu; Bae, Hojae; Kim, Changsung; Byun, Sung June; Do, Jeong Tae

    2017-01-01

    Like embryonic stem cells, induced pluripotent stem cells (iPSCs) can differentiate into all three germ layers in an in vitro system. Here, we developed a new technology for obtaining neural stem cells (NSCs) from iPSCs through chimera formation, in an in vivo environment. iPSCs contributed to the neural lineage in the chimera, which could be efficiently purified and directly cultured as NSCs in vitro. The iPSC-derived, in vivo-differentiated NSCs expressed NSC markers, and their gene-expression pattern more closely resembled that of fetal brain-derived NSCs than in vitro-differentiated NSCs. This system could be applied for differentiating pluripotent stem cells into specialized cell types whose differentiation protocols are not well established. PMID:28141814

  16. Apolipoprotein AI and Transthyretin as Components of Amyloid Fibrils in a Kindred with apoAI Leu178His Amyloidosis

    PubMed Central

    de Sousa, Mónica Mendes; Vital, Claude; Ostler, Dominique; Fernandes, Rui; Pouget-Abadie, Jean; Carles, Dominique; Saraiva, Maria João

    2000-01-01

    We found a new C-terminal amyloidogenic variant of apolipoprotein AI (apoAI), Leu178His in a French kindred, associated with cardiac and larynx amyloidosis and skin lesions with onset during the fourth decade. This single-point mutation in exon 4 of the apoAI gene was detected by DNA sequencing of polymerase chain reaction amplified material and restriction fragment length polymorphism analysis in two siblings. Blood, larynx, and skin biopsies were available from one sibling. Anti-apoAI immunoblotting of isoelectric focusing of plasma showed a +1 alteration in the charge of the protein. Extraction of fibrils from the skin biopsy revealed both full-length and N-terminal fragments of apoAI and transthyretin (TTR). ApoAI and TTR co-localized in amyloid deposits as demonstrated by immunohistochemistry. The present report, together with the first recently described C-terminal amyloidogenic variant of apoAI, Arg173Pro, shows that amyloidogenicity of apoAI is not a feature exclusive to N-terminal variants. The most striking characteristic of amyloid fibrils in Leu178His is that wild-type TTR is co-localized with apoAI in the fibrils. We have previously determined that a fraction of plasma TTR circulates in plasma bound to high-density lipoprotein and that this interaction occurs through binding to apoAI. Therefore we hypothesize that nonmutated TTR might influence deposition of apoAI as amyloid. PMID:10854214

  17. Apolipoprotein AI and transthyretin as components of amyloid fibrils in a kindred with apoAI Leu178His amyloidosis.

    PubMed

    de Sousa, M M; Vital, C; Ostler, D; Fernandes, R; Pouget-Abadie, J; Carles, D; Saraiva, M J

    2000-06-01

    We found a new C-terminal amyloidogenic variant of apolipoprotein AI (apoAI), Leu178His in a French kindred, associated with cardiac and larynx amyloidosis and skin lesions with onset during the fourth decade. This single-point mutation in exon 4 of the apoAI gene was detected by DNA sequencing of polymerase chain reaction amplified material and restriction fragment length polymorphism analysis in two siblings. Blood, larynx, and skin biopsies were available from one sibling. Anti-apoAI immunoblotting of isoelectric focusing of plasma showed a +1 alteration in the charge of the protein. Extraction of fibrils from the skin biopsy revealed both full-length and N-terminal fragments of apoAI and transthyretin (TTR). ApoAI and TTR co-localized in amyloid deposits as demonstrated by immunohistochemistry. The present report, together with the first recently described C-terminal amyloidogenic variant of apoAI, Arg173Pro, shows that amyloidogenicity of apoAI is not a feature exclusive to N-terminal variants. The most striking characteristic of amyloid fibrils in Leu178His is that wild-type TTR is co-localized with apoAI in the fibrils. We have previously determined that a fraction of plasma TTR circulates in plasma bound to high-density lipoprotein and that this interaction occurs through binding to apoAI. Therefore we hypothesize that nonmutated TTR might influence deposition of apoAI as amyloid.

  18. Structure-based discovery and experimental verification of novel AI-2 quorum sensing inhibitors against Vibrio harveyi.

    PubMed

    Li, Minyong; Ni, Nanting; Chou, Han-Ting; Lu, Chung-Dar; Tai, Phang C; Wang, Binghe

    2008-08-01

    Quorum sensing has been implicated in the control of pathologically relevant bacterial behavior such as secretion of virulence factors, biofilm formation, sporulation, and swarming motility. The AI-2 quorum sensing pathway is found in both gram-positive and gram-negative bacteria. Therefore, antagonizing AI-2 quorum sensing is a possible approach to modifying bacterial behaviour. However, efforts in developing inhibitors of AI-2-mediated quorum sensing are especially lacking. High-throughput virtual screening using the V. harveyi LuxP crystal structure identified two compounds that were found to antagonize AI-2-mediated quorum sensing in V. harveyi without cytotoxicity. The sulfone functionality of these inhibitors was identified as critical to their ability to mimic the natural ligand in their interactions with Arg 215 and Arg 310 of the active site.

  19. Thiophenone Attenuates Enteropathogenic Escherichia coli O103:H2 Virulence by Interfering with AI-2 Signaling

    PubMed Central

    Valen Rukke, Håkon; Benneche, Tore; Aamdal Scheie, Anne

    2016-01-01

    Interference with bacterial quorum sensing communication provides an anti-virulence strategy to control pathogenic bacteria. Here, using the Enteropathogenic E. coli (EPEC) O103:H2, we showed for the first time that thiophenone TF101 reduced expression of lsrB; the gene encoding the AI-2 receptor. Combined results of transcriptional and phenotypic analyses suggested that TF101 interfere with AI-2 signalling, possibly by competing with AI-2 for binding to LsrB. This is supported by in silico docking prediction of thiophenone TF101 in the LsrB pocket. Transcriptional analyses furthermore showed that thiophenone TF101 interfered with expression of the virulence genes eae and fimH. In addition, TF101 reduced AI-2 induced E. coli adhesion to colorectal adenocarcinoma cells. TF101, on the other hand, did not affect epinephrine or norepinephrine enhanced E. coli adhesion. Overall, our results showed that thiophenone TF101 interfered with virulence expression in E. coli O103:H2, suggestedly by interfering with AI-2 mediated quorum sensing. We thus conclude that thiophenone TF101 might represent a promising future anti-virulence agent in the fight against pathogenic E. coli. PMID:27309855

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

    PubMed

    Seirin Lee, Sungrim

    2016-09-07

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

  1. Interordinal chimera formation between medaka and zebrafish for analyzing stem cell differentiation.

    PubMed

    Hong, Ni; Chen, Songlin; Ge, Ruowen; Song, Jianxing; Yi, Meisheng; Hong, Yunhan

    2012-08-10

    Chimera formation is a standard test for pluripotency of stem cells in vivo. Interspecific chimera formation between distantly related organisms offers also an attractive approach for propagating endangered species. Parameters influencing interspecies chimera formation have remained poorly elucidated. Here, we report interordinal chimera formation between medaka and zebrafish, which separated ∼320 million years ago and exhibit a more than 2-fold difference in developmental speed. We show that, on transplantation into zebrafish blastulae, both noncultivated blastomeres and long-term cultivated embryonic stem (ES) cells of medaka adopted the zebrafish developmental program and differentiated into physiologically functional cell types including pigment cells, blood cells, and cardiomyocytes. We also show that medaka ES cells express differentiation gene markers during chimeric embryogenesis. Therefore, the evolutionary distance and different embryogenesis speeds do not produce donor-host incompatibility to compromise chimera formation between medaka and zebrafish, and molecular markers are valuable for analyzing lineage commitment and cell differentiation in interspecific chimeric embryos.

  2. Formation of thin walled ceramic solid oxide fuel cells

    DOEpatents

    Claar, Terry D.; Busch, Donald E.; Picciolo, John J.

    1989-01-01

    To reduce thermal stress and improve bonding in a high temperature monolithic solid oxide fuel cell (SOFC), intermediate layers are provided between the SOFC's electrodes and electrolyte which are of different compositions. The intermediate layers are comprised of a blend of some of the materials used in the electrode and electrolyte compositions. Particle size is controlled to reduce problems involving differential shrinkage rates of the various layers when the entire structure is fired at a single temperature, while pore formers are provided in the electrolyte layers to be removed during firing for the formation of desired pores in the electrode layers. Each layer includes a binder in the form of a thermosetting acrylic which during initial processing is cured to provide a self-supporting structure with the ceramic components in the green state. A self-supporting corrugated structure is thus formed prior to firing, which the organic components of the binder and plasticizer removed during firing to provide a high strength, high temperature resistant ceramic structure of low weight and density.

  3. AIS spectra of desert shrub canopies

    NASA Technical Reports Server (NTRS)

    Murray, R.; Isaacson, D. L.; Schrumpf, B. J.; Ripple, W. J.; Lewis, A. J.

    1986-01-01

    Airborne Imaging Spectrometer (AIS) data were collected 30 August 1985 from a desert shrub community in central Oregon. Spectra from artificial targets placed on the test site and from bare soil, big sagebrush (Artemesia tridentata wyomingensis), silver sagebrush (Artemesia cana bolander), and exposed volcanic rocks were studied. Spectral data from grating position 3 (tree mode) were selected from 25 ground positions for analysis by Principal Factor Analysis (PFA). In this grating position, as many as six factors were identified as significant in contributing to spectral structure. Channels 74 through 84 (tree mode) best characterized between-class differences. Other channels were identified as nondiscriminating and as associated with such errors as excessive atmospheric absorption and grating positin changes. The test site was relatively simple with the two species (A. tridentata and A. cana) representing nearly 95% of biomass and with only two mineral backgrounds, a montmorillonitic soil and volcanic rocks. If, as in this study, six factors of spectral structure can be extracted from a single grating position from data acquired over a simple vegetation community, then AIS data must be considered rich in information-gathering potential.

  4. AI techniques in geomagnetic storm forecasting

    NASA Astrophysics Data System (ADS)

    Lundstedt, Henrik

    This review deals with how geomagnetic storms can be predicted with the use of Artificial Intelligence (AI) techniques. Today many different Al techniques have been developed, such as symbolic systems (expert and fuzzy systems) and connectionism systems (neural networks). Even integrations of AI techniques exist, so called Intelligent Hybrid Systems (IHS). These systems are capable of learning the mathematical functions underlying the operation of non-linear dynamic systems and also to explain the knowledge they have learned. Very few such powerful systems exist at present. Two such examples are the Magnetospheric Specification Forecast Model of Rice University and the Lund Space Weather Model of Lund University. Various attempts to predict geomagnetic storms on long to short-term are reviewed in this article. Predictions of a month to days ahead most often use solar data as input. The first SOHO data are now available. Due to the high temporal and spatial resolution new solar physics have been revealed. These SOHO data might lead to a breakthrough in these predictions. Predictions hours ahead and shorter rely on real-time solar wind data. WIND gives us real-time data for only part of the day. However, with the launch of the ACE spacecraft in 1997, real-time data during 24 hours will be available. That might lead to the second breakthrough for predictions of geomagnetic storms.

  5. The contribution of cell-cell signaling and motility to bacterial biofilm formation

    PubMed Central

    Shrout, Joshua D.; Tolker-Nielsen, Tim; Givskov, Michael; Parsek, Matthew R.

    2011-01-01

    Many bacteria grow attached to a surface as biofilms. Several factors dictate biofilm formation, including responses by the colonizing bacteria to their environment. Here we review how bacteria use cell-cell signaling (also called quorum sensing) and motility during biofilm formation. Specifically, we describe quorum sensing and surface motility exhibited by the bacterium Pseudomonas aeruginosa, a ubiquitous environmental organism that acts as an opportunistic human pathogen in immunocompromised individuals. P. aeruginosa uses acyl-homoserine lactone signals during quorum sensing to synchronize gene expression important to the production of polysaccharides, rhamnolipid, and other virulence factors. Surface motility affects the assembly and architecture of biofilms, and some aspects of motility are also influenced by quorum sensing. While some genes and their function are specific to P. aeruginosa, many aspects of biofilm development can be used as a model system to understand how bacteria differentially colonize surfaces. PMID:22053126

  6. Expression of an accessory cell phenotype by hairy cells during lymphocyte colony formation in agar culture.

    PubMed

    Farcet, J P; Gourdin, M F; Testa, U; Andre, C; Jouault, H; Reyes, F

    1983-01-01

    Human T lymphocytes require the cooperation of accessory cells to generate lymphocyte colonies in agar culture under PHA stimulation. Various hairy cell enriched fractions, as well as normal monocytes, have been found to be able to initiate colony formation by normal lymphocytes. Leukemic monocytes from CMML patients were also effective, but not the leukemic lymphocytes from CLL patients. The phenotype expressed by HC in agar colonies was further studied using cell surface and enzymatic markers. We have concluded that HC in agar culture in the presence of both normal T lymphocytes and PHA lose the B phenotype that they express in vivo and function like an accessory cell in contrast to normal or leukemic B lymphocytes.

  7. Effect of uneven red cell influx on formation of cell-free layer in small venules.

    PubMed

    Namgung, Bumseok; Kim, Sangho

    2014-03-01

    This study examined how the uneven influx of red blood cells (RBCs) from feeding vessels influences formation of cell-free layer (CFL) in the downstream vessel of a venular bifurcation. Spatio-temporal variations of the CFL width along the downstream vessel (19-41-μm inner diameter, D) were determined at 0.5D intervals from 0.5D to 3.0D away from the bifurcation. Upstream flow conditions were quantified by the ratio of volume flow rates (Q*=Q(High)/Q(Low)) between high flow (Q(High)) and low flow feeding (Q(Low)) vessels. The RBC aggregation level in the rats was adjusted to be at healthy human levels by infusing Dextran 500. Our results suggested that the CFL formation process could be seen only from 2.0D away from the bifurcating point. The mean CFL width at the wall adjacent to the feeding vessel with a higher flow rate was consistently greater than that at the opposite wall, leading to an asymmetric CFL formation in the vessel. A positive relation (P<0.05) between the asymmetry of the CFL width and the volume flow rate ratio (Q*) was found. Our numerical prediction showed that flow resistance in the venular network could be significantly increased by the asymmetric formation of CFL downstream and this effect might become more pronounced under pathological flow conditions such as hyper-aggregating and/or low shear conditions.

  8. Proteomic analysis to identify the role of luxS/AI-2 mediated protein expression in Escherichia coli O157:H7

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Autoinducer molecules are used by several microorganisms to control various bacterial 5 processes including virulence expression, biofilm and bioluminescence. The universal 6 autoinducer molecule AI-2 is hypothesized to mediate cell signaling in E. coli O157:H7. We investigated the role of AI-2 on...

  9. A LuxS-dependent cell-to-cell language regulates social behavior and development in Bacillus subtilis.

    PubMed

    Lombardía, Esteban; Rovetto, Adrián J; Arabolaza, Ana L; Grau, Roberto R

    2006-06-01

    Cell-to-cell communication in bacteria is mediated by quorum-sensing systems (QSS) that produce chemical signal molecules called autoinducers (AI). In particular, LuxS/AI-2-dependent QSS has been proposed to act as a universal lexicon that mediates intra- and interspecific bacterial behavior. Here we report that the model organism Bacillus subtilis operates a luxS-dependent QSS that regulates its morphogenesis and social behavior. We demonstrated that B. subtilis luxS is a growth-phase-regulated gene that produces active AI-2 able to mediate the interspecific activation of light production in Vibrio harveyi. We demonstrated that in B. subtilis, luxS expression was under the control of a novel AI-2-dependent negative regulatory feedback loop that indicated an important role for AI-2 as a signaling molecule. Even though luxS did not affect spore development, AI-2 production was negatively regulated by the master regulatory proteins of pluricellular behavior, SinR and Spo0A. Interestingly, wild B. subtilis cells, from the undomesticated and probiotic B. subtilis natto strain, required the LuxS-dependent QSS to form robust and differentiated biofilms and also to swarm on solid surfaces. Furthermore, LuxS activity was required for the formation of sophisticated aerial colonies that behaved as giant fruiting bodies where AI-2 production and spore morphogenesis were spatially regulated at different sites of the developing colony. We proposed that LuxS/AI-2 constitutes a novel form of quorum-sensing regulation where AI-2 behaves as a morphogen-like molecule that coordinates the social and pluricellular behavior of B. subtilis.

  10. Applying AI tools to operational space environmental analysis

    NASA Technical Reports Server (NTRS)

    Krajnak, Mike; Jesse, Lisa; Mucks, John

    1995-01-01

    The U.S. Air Force and National Oceanic Atmospheric Agency (NOAA) space environmental operations centers are facing increasingly complex challenges meeting the needs of their growing user community. These centers provide current space environmental information and short term forecasts of geomagnetic activity. Recent advances in modeling and data access have provided sophisticated tools for making accurate and timely forecasts, but have introduced new problems associated with handling and analyzing large quantities of complex data. AI (Artificial Intelligence) techniques have been considered as potential solutions to some of these problems. Fielding AI systems has proven more difficult than expected, in part because of operational constraints. Using systems which have been demonstrated successfully in the operational environment will provide a basis for a useful data fusion and analysis capability. Our approach uses a general purpose AI system already in operational use within the military intelligence community, called the Temporal Analysis System (TAS). TAS is an operational suite of tools supporting data processing, data visualization, historical analysis, situation assessment and predictive analysis. TAS includes expert system tools to analyze incoming events for indications of particular situations and predicts future activity. The expert system operates on a knowledge base of temporal patterns encoded using a knowledge representation called Temporal Transition Models (TTM's) and an event database maintained by the other TAS tools. The system also includes a robust knowledge acquisition and maintenance tool for creating TTM's using a graphical specification language. The ability to manipulate TTM's in a graphical format gives non-computer specialists an intuitive way of accessing and editing the knowledge base. To support space environmental analyses, we used TAS's ability to define domain specific event analysis abstractions. The prototype system defines

  11. Receptor-like kinase ACR4 restricts formative cell divisions in the Arabidopsis root.

    PubMed

    De Smet, Ive; Vassileva, Valya; De Rybel, Bert; Levesque, Mitchell P; Grunewald, Wim; Van Damme, Daniël; Van Noorden, Giel; Naudts, Mirande; Van Isterdael, Gert; De Clercq, Rebecca; Wang, Jean Y; Meuli, Nicholas; Vanneste, Steffen; Friml, Jirí; Hilson, Pierre; Jürgens, Gerd; Ingram, Gwyneth C; Inzé, Dirk; Benfey, Philip N; Beeckman, Tom

    2008-10-24

    During the development of multicellular organisms, organogenesis and pattern formation depend on formative divisions to specify and maintain pools of stem cells. In higher plants, these activities are essential to shape the final root architecture because the functioning of root apical meristems and the de novo formation of lateral roots entirely rely on it. We used transcript profiling on sorted pericycle cells undergoing lateral root initiation to identify the receptor-like kinase ACR4 of Arabidopsis as a key factor both in promoting formative cell divisions in the pericycle and in constraining the number of these divisions once organogenesis has been started. In the root tip meristem, ACR4 shows a similar action by controlling cell proliferation activity in the columella cell lineage. Thus, ACR4 function reveals a common mechanism of formative cell division control in the main root tip meristem and during lateral root initiation.

  12. Dynamics of phragmoplastin in living cells during cell plate formation and uncoupling of cell elongation from the plane of cell division.

    PubMed Central

    Gu, X; Verma, D P

    1997-01-01

    The cell plate is formed by the fusion of Golgi apparatus-derived vesicles in the center of the phragmoplast during cytokinesis in plant cells. A dynamin-like protein, phragmoplastin, has been isolated and shown to be associated with cell plate formation in soybean by using immunocytochemistry. In this article, we demonstrate that similar to dynamin, phragmoplastin polymerizes to form oligomers. We fused soybean phragmoplastin with the green fluorescence protein (GFP) and introduced it into tobacco BY-2 cells to monitor the dynamics of early events in cell plate formation. We demonstrate that the chimeric protein is functional and targeted to the cell plate during cytokinesis in transgenic cells. GFP-phragmoplastin was found to appear first in the center of the forming cell plate, and as the cell plate grew outward, it redistributed to the growing margins of the cell plate. The redistribution of phragmoplastin may require microtubule reorganization because the microtubule-stabilizing drug taxol inhibited phragmoplastin redistribution. Our data show that throughout the entire process of cytokinesis, phragmoplastin is concentrated in the area in which membrane fusion is active, suggesting that phragmoplastin participates in an early membrane fusion event during cell plate formation. Based on the dynamics of GFP-phragmoplastin, it appears that the process of cell plate formation is completed in two phases. The first phase is confined to the cylinder of the phragmoplast proper and is followed by a second phase that deposits phragmoplast vesicles in a concentric fashion, resulting in a ring of fluorescence, with the concentration of vesicles being higher at the periphery. In addition, overexpression of GFP-phragmoplastin appears to act as a dominant negative, slowing down the completion of cell plate formation, and often results in an oblique cell plate. The latter appears to uncouple cell elongation from the plane of cell division, forming twisted and elongated cells

  13. Opposite regulation of human versus mouse apolipoprotein A-I by fibrates in human apolipoprotein A-I transgenic mice.

    PubMed Central

    Berthou, L; Duverger, N; Emmanuel, F; Langouët, S; Auwerx, J; Guillouzo, A; Fruchart, J C; Rubin, E; Denèfle, P; Staels, B; Branellec, D

    1996-01-01

    The regulation of liver apolipoprotein (apo) A-I gene expression by fibrates was studied in human apo A-I transgenic mice containing a human genomic DNA fragment driving apo A-I expression in liver. Treatment with fenofibrate (0.5% wt/wt) for 7 d increased plasma human apo A-I levels up to 750% and HDL-cholesterol levels up to 200% with a shift to larger particles. The increase in human apo A-I plasma levels was time and dose dependent and was already evident after 3 d at the highest dose (0.5% wt/wt) of fenofibrate. In contrast, plasma mouse apo A-I concentration was decreased after fenofibrate in nontransgenic mice. The increase in plasma human apo A-I levels after fenofibrate treatment was associated with a 97% increase in hepatic human apo A-I mRNA, whereas mouse apo A-I mRNA levels decreased to 51%. In nontransgenic mice, a similar down-regulation of hepatic apo A-I mRNA levels was observed. Nuclear run-on experiments demonstrated that the increase in human apo A-I and the decrease in mouse apo A-I gene expression after fenofibrate occurred at the transcriptional level. Since part of the effects of fibrates are mediated through the nuclear receptor PPAR (peroxisome proliferator-activated receptor), the expression of the acyl CoA oxidase (ACO) gene was measured as a control of PPAR activation. Both in transgenic and nontransgenic mice, fenofibrate induced ACO mRNA levels up to sixfold. When transgenic mice were treated with gemfibrozil (0.5% wt/wt) plasma human apo A-I and HDL-cholesterol levels increased 32 and 73%, respectively, above control levels. The weaker effect of this compound on human apo A-I and HDL-cholesterol levels correlated with a less pronounced impact on ACO mRNA levels (a threefold increase) suggesting that the level of induction of human apo A-I gene is related to the PPAR activating potency of the fibrate used. Treatment of human primary hepatocytes with fenofibric acid (500 microM) provoked an 83 and 50% increase in apo A-I secretion and

  14. Aggregate formation affects ultrasonic disruption of microalgal cells.

    PubMed

    Wang, Wei; Lee, Duu-Jong; Lai, Juin-Yih

    2015-12-01

    Ultrasonication is a cell disruption process of low energy efficiency. This study dosed K(+), Ca(2+) and Al(3+) to Chlorella vulgaris cultured in Bold's Basal Medium at 25°C and measured the degree of cell disruption under ultrasonication. Adding these metal ions yielded less negatively charged surfaces of cells, while with the latter two ions large and compact cell aggregates were formed. The degree of cell disruption followed: control=K(+)>Ca(2+)>Al(3+) samples. Surface charges of cells and microbubbles have minimal effects on the microbubble number in the proximity of the microalgal cells. Conversely, cell aggregates with large size and compact interior resist cell disruption under ultrasonication. Staining tests revealed high diffusional resistance of stains over the aggregate interior. Microbubbles may not be effective generated and collapsed inside the compact aggregates, hence leading to low cell disruption efficiencies. Effective coagulation/flocculation in cell harvesting may lead to adverse effect on subsequent cell disruption efficiency.

  15. The implementation of AI technologies in computer wargames

    NASA Astrophysics Data System (ADS)

    Tiller, John A.

    2004-08-01

    Computer wargames involve the most in-depth analysis of general game theory. The enumerated turns of a game like chess are dwarfed by the exponentially larger possibilities of even a simple computer wargame. Implementing challenging AI is computer wargames is an important goal in both the commercial and military environments. In the commercial marketplace, customers demand a challenging AI opponent when they play a computer wargame and are frustrated by a lack of competence on the part of the AI. In the military environment, challenging AI opponents are important for several reasons. A challenging AI opponent will force the military professional to avoid routine or set-piece approaches to situations and cause them to think much deeper about military situations before taking action. A good AI opponent would also include national characteristics of the opponent being simulated, thus providing the military professional with even more of a challenge in planning and approach. Implementing current AI technologies in computer wargames is a technological challenge. The goal is to join the needs of AI in computer wargames with the solutions of current AI technologies. This talk will address several of those issues, possible solutions, and currently unsolved problems.

  16. Quantifying the tracking capability of space-based AIS systems

    NASA Astrophysics Data System (ADS)

    Skauen, Andreas Nordmo

    2016-01-01

    The Norwegian Defence Research Establishment (FFI) has operated three Automatic Identification System (AIS) receivers in space. Two are on dedicated nano-satellites, AISSat-1 and AISSat-2. The third, the NORAIS Receiver, was installed on the International Space Station. A general method for calculating the upper bound on the tracking capability of a space-based AIS system has been developed and the results from the algorithm applied to AISSat-1 and the NORAIS Receiver individually. In addition, a constellation of AISSat-1 and AISSat-2 is presented. The tracking capability is defined as the probability of re-detecting ships as they move around the globe and is explained to represent and upper bound on a space-based AIS system performance. AISSat-1 and AISSat-2 operates on the nominal AIS1 and AIS2 channels, while the NORAIS Receiver data used are from operations on the dedicated space AIS channels, AIS3 and AIS4. The improved tracking capability of operations on the space AIS channels is presented.

  17. Myotube formation is affected by adipogenic lineage cells in a cell-to-cell contact-independent manner

    SciTech Connect

    Takegahara, Yuki; Yamanouchi, Keitaro Nakamura, Katsuyuki; Nakano, Shin-ichi; Nishihara, Masugi

    2014-05-15

    Intramuscular adipose tissue (IMAT) formation is observed in some pathological conditions such as Duchenne muscular dystrophy (DMD) and sarcopenia. Several studies have suggested that IMAT formation is not only negatively correlated with skeletal muscle mass but also causes decreased muscle contraction in sarcopenia. In the present study, we examined w hether adipocytes affect myogenesis. For this purpose, skeletal muscle progenitor cells were transfected with siRNA of PPARγ (siPPARγ) in an attempt to inhibit adipogenesis. Myosin heavy chain (MHC)-positive myotube formation was promoted in cells transfected with siPPARγ compared to that of cells transfected with control siRNA. To determine whether direct cell-to-cell contact between adipocytes and myoblasts is a prerequisite for adipocytes to affect myogenesis, skeletal muscle progenitor cells were cocultured with pre- or mature adipocytes in a Transwell coculture system. MHC-positive myotube formation was inhibited when skeletal muscle progenitor cells were cocultured with mature adipocytes, but was promoted when they were cocultured with preadipocytes. Similar effects were observed when pre- or mature adipocyte-conditioned medium was used. These results indicate that preadipocytes play an important role in maintaining skeletal muscle mass by promoting myogenesis; once differentiated, the resulting mature adipocytes negatively affect myogenesis, leading to the muscle deterioration observed in skeletal muscle pathologies. - Highlights: • We examined the effects of pre- and mature adipocytes on myogenesis in vitro. • Preadipocytes and mature adipocytes affect myoblast fusion. • Preadipocytes play an important role in maintaining skeletal muscle mass. • Mature adipocytes lead to muscle deterioration observed in skeletal muscle pathologies.

  18. AI tools in computer based problem solving

    NASA Technical Reports Server (NTRS)

    Beane, Arthur J.

    1988-01-01

    The use of computers to solve value oriented, deterministic, algorithmic problems, has evolved a structured life cycle model of the software process. The symbolic processing techniques used, primarily in research, for solving nondeterministic problems, and those for which an algorithmic solution is unknown, have evolved a different model, much less structured. Traditionally, the two approaches have been used completely independently. With the advent of low cost, high performance 32 bit workstations executing identical software with large minicomputers and mainframes, it became possible to begin to merge both models into a single extended model of computer problem solving. The implementation of such an extended model on a VAX family of micro/mini/mainframe systems is described. Examples in both development and deployment of applications involving a blending of AI and traditional techniques are given.

  19. Human Frontal Lobes and AI Planning Systems

    NASA Technical Reports Server (NTRS)

    Levinson, Richard; Lum, Henry Jr. (Technical Monitor)

    1994-01-01

    Human frontal lobes are essential for maintaining a self-regulating balance between predictive and reactive behavior. This paper describes a system that integrates prediction and reaction based on neuropsychological theories of frontal lobe function. In addition to enhancing our understanding of deliberate action in humans' the model is being used to develop and evaluate the same properties in machines. First, the paper presents some background neuropsychology in order to set a general context. The role of frontal lobes is then presented by summarizing three theories which formed the basis for this work. The components of an artificial frontal lobe are then discussed from both neuropsychological and AI perspectives. The paper concludes by discussing issues and methods for evaluating systems that integrate planning and reaction.

  20. Application of AIS Technology to Forest Mapping

    NASA Technical Reports Server (NTRS)

    Yool, S. R.; Star, J. L.

    1985-01-01

    Concerns about environmental effects of large scale deforestation have prompted efforts to map forests over large areas using various remote sensing data and image processing techniques. Basic research on the spectral characteristics of forest vegetation are required to form a basis for development of new techniques, and for image interpretation. Examination of LANDSAT data and image processing algorithms over a portion of boreal forest have demonstrated the complexity of relations between the various expressions of forest canopies, environmental variability, and the relative capacities of different image processing algorithms to achieve high classification accuracies under these conditions. Airborne Imaging Spectrometer (AIS) data may in part provide the means to interpret the responses of standard data and techniques to the vegetation based on its relatively high spectral resolution.

  1. AI And Early Vision - Part II

    NASA Astrophysics Data System (ADS)

    Julesz, Bela

    1989-08-01

    A quarter of a century ago I introduced two paradigms into psychology which in the intervening years have had a direct impact on the psychobiology of early vision and an indirect one on artificial intelligence (AI or machine vision). The first, the computer-generated random-dot stereogram (RDS) paradigm (Julesz, 1960) at its very inception posed a strategic question both for AI and neurophysiology. The finding that stereoscopic depth perception (stereopsis) is possible without the many enigmatic cues of monocular form recognition - as assumed previously - demonstrated that stereopsis with its basic problem of finding matches between corresponding random aggregates of dots in the left and right visual fields became ripe for modeling. Indeed, the binocular matching problem of stereopsis opened up an entire field of study, eventually leading to the computational models of David Marr (1982) and his coworkers. The fusion of RDS had an even greater impact on neurophysiologists - including Hubel and Wiesel (1962) - who realized that stereopsis must occur at an early stage, and can be studied easier than form perception. This insight recently culminated in the studies by Gian Poggio (1984) who found binocular-disparity - tuned neurons in the input stage to the visual cortex (layer IVB in V1) in the monkey that were selectively triggered by dynamic RDS. Thus the first paradigm led to a strategic insight: that with stereoscopic vision there is no camouflage, and as such was advantageous for our primate ancestors to evolve the cortical machinery of stereoscopic vision to capture camouflaged prey (insects) at a standstill. Amazingly, although stereopsis evolved relatively late in primates, it captured the very input stages of the visual cortex. (For a detailed review, see Julesz, 1986a)

  2. Complement-dependent control of teratoma formation by embryonic stem cells.

    PubMed

    Koch, Cody A; Jordan, Corinne E; Platt, Jeffrey L

    2006-10-01

    The fetus has pluripotent stem cells that when transferred to mature individuals can generate tumors. However, for reasons yet unknown, tumors form rarely in the fetus and/or the mother during normal gestation. We questioned whether the complement system might protect against tumor formation by pluripotent stem cells. Murine embryonic stem cells were notably more susceptible than cardiomyocytes differentiated from those cells to lysis by complement in heterologous and homologous sera. Treatment of embryonic stem cells with heterologous serum averted tumor formation after residual cells were transplanted into mice. Confirming the importance of homologous complement in preventing formation of tumors, untreated embryonic stem cells formed tumors more quickly in C3-deficient than in wild-type mice. Susceptibility of embryonic stem cells to complement required an intact alternative pathway and was owed at least in part to a relative deficiency of sialic acid on cell surfaces compared with differentiated cells. Susceptibility to complement and resistance to tumors was inversely related to the number of cells transferred. These findings show that formation of tumors from embryonic stem cells is controlled in part by the alternative pathway of complement and suggest that susceptibility to complement might represent a general property of pluripotent stem cells that can be exploited to prevent tumor formation.

  3. Establishment of cell polarity by afadin during the formation of embryoid bodies.

    PubMed

    Komura, Hitomi; Ogita, Hisakazu; Ikeda, Wataru; Mizoguchi, Akira; Miyoshi, Jun; Takai, Yoshimi

    2008-01-01

    Afadin directly links nectin, an immunoglobulin-like cell-cell adhesion molecule, to actin filaments (F-actin) at adherens junctions (AJs). The nectin-afadin complex is important for the formation of not only AJs but also tight junctions (TJs) in epithelial cells. Studies using afadin-knockout mice have revealed that afadin is indispensable for embryonic development by organizing the formation of cell-cell junctions. However, the molecular mechanism of cell-cell junction disorganization during embryonic development in afadin-knockout mice is poorly understood. To address this, we took advantage of embryoid bodies (EBs) as a model system. The formation of cell-cell junctions including AJs and TJs was impaired in afadin-null EBs. The proper accumulation of the Par complex and the activation of Cdc42 and atypical PKC (aPKC), which are crucial for the formation of cell polarity, were also inhibited by knockout of afadin. In addition, the disruption of afadin caused the abnormal deposition of laminin and the dislocalization of its receptors integrin alpha(6) and integrin beta(1). These results indicate that afadin organizes the formation of cell-cell junctions by regulating cell polarization in early embryonic development.

  4. Multinuclear giant cell formation is enhanced by down-regulation of Wnt signaling in gastric cancer cell line, AGS

    SciTech Connect

    Kim, Shi-Mun; Kim, Rockki; Ryu, Jae-Hyun; Jho, Eek-Hoon; Song, Ki-Joon; Jang, Shyh-Ing; Kee, Sun-Ho . E-mail: keesh@korea.ac.kr

    2005-08-01

    AGS cells, which were derived from malignant gastric adenocarcinoma tissue, lack E-cadherin-mediated cell adhesion but have a high level of nuclear {beta}-catenin, which suggests altered Wnt signal. In addition, approximately 5% of AGS cells form multinuclear giant cells in the routine culture conditions, while taxol treatment causes most AGS cells to become giant cells. The observation of reduced nuclear {beta}-catenin levels in giant cells induced by taxol treatment prompted us to investigate the relationship between Wnt signaling and giant cell formation. After overnight serum starvation, the shape of AGS cells became flattened, and this morphological change was accompanied by decrease in Myc expression and an increase in the giant cell population. Lithium chloride treatment, which inhibits GSK3{beta} activity, reversed these serum starvation effects, which suggests an inverse relationship between Wnt signaling and giant cell formation. Furthermore, the down-regulation of Wnt signaling caused by the over-expression of ICAT, E-cadherin, and Axin enhanced giant cell formation. Therefore, down-regulation of Wnt signaling may be related to giant cell formation, which is considered to be a survival mechanism against induced cell death.

  5. Interaction of human apolipoprotein A-I with model membranes exhibiting lipid domains.

    PubMed

    Arnulphi, Cristina; Sánchez, Susana A; Tricerri, M Alejandra; Gratton, Enrico; Jonas, Ana

    2005-07-01

    Several mechanisms for cell cholesterol efflux have been proposed, including membrane microsolubilization, suggesting that the existence of specific domains could enhance the transfer of lipids to apolipoproteins. In this work isothermal titration calorimetry, circular dichroism spectroscopy, and two-photon microscopy are used to study the interaction of lipid-free apolipoprotein A-I (apoA-I) with small unilamellar vesicles (SUVs) of 1-palmitoyl, 2-oleoyl phosphatidylcholine (POPC) and sphingomyelin (SM), with and without cholesterol. Below 30 degrees C the calorimetric results show that apoA-I interaction with POPC/SM SUVs produces an exothermic reaction, characterized as nonclassical hydrophobic binding. The heat capacity change (DeltaCp degrees ) is small and positive, whereas it was larger and negative for pure POPC bilayers, in the absence of SM. Inclusion of cholesterol in the membranes induces changes in the observed thermodynamic pattern of binding and counteracts the formation of alpha-helices in the protein. Above 30 degrees C the reactions are endothermic. Giant unilamellar vesicles (GUVs) of identical composition to the SUVs, and two-photon fluorescence microscopy techniques, were utilized to further characterize the interaction. Fluorescence imaging of the GUVs indicates coexistence of lipid domains under 30 degrees C. Binding experiments and Laurdan generalized-polarization measurements suggest that there is no preferential binding of the labeled apoA-I to any particular domain. Changes in the content of alpha-helix, binding, and fluidity data are discussed in the framework of the thermodynamic parameters.

  6. Live-Cell Analysis of Mitotic Spindle Formation in Taxol-Treated Cells

    PubMed Central

    Hornick, Jessica E.; Bader, Jason R.; Tribble, Emily K.; Trimble, Kayleigh; Breunig, J. Scott; Halpin, Elizabeth S.; Vaughan, Kevin T.; Hinchcliffe, Edward H.

    2009-01-01

    Taxol functions to suppress the dynamic behavior of individual microtubules, and induces multipolar mitotic spindles. However, little is known about the mechanisms by which taxol disrupts normal bipolar spindle assembly in vivo. Using live imaging of GFP-α tubulin expressing cells, we examined spindle assembly after taxol treatment. We find that as taxol-treated cells enter mitosis, there is a dramatic redistribution of the microtubule network from the centrosomes to the cell cortex. As they align there, the cortical microtubules recruit NuMA to their embedded ends, followed by the kinesin motor HSET. These cortical microtubules then bud off to form cytasters, which fuse into multipolar spindles. Cytoplasmic dynein and dynactin do not re-localize to cortical microtubules, and disruption of dynein/dynactin interactions by over-expression of p50 “dynamitin” does not prevent cytaster formation. Taxol added well before spindle poles begin to form induces multipolarity, but taxol added after nascent spindle poles are visible—but before NEB is complete—results in bipolar spindles. Our results suggest that taxol prevents rapid transport of key components, such as NuMA, to the nascent spindle poles. The net result is loss of mitotic spindle pole cohesion, microtubule re-distribution, and cytaster formation. PMID:18481305

  7. Tunneling nanotube formation is stimulated by hypoxia in ovarian cancer cells

    PubMed Central

    Vogel, Rachel I.; Thayanithy, Venugopal; Wong, Phillip; Teoh, Deanna; Geller, Melissa A.; Steer, Clifford J.; Subramanian, Subbaya; Lou, Emil

    2016-01-01

    In this study, we demonstrated that hypoxic conditions stimulated an increase in tunneling nanotube (TNT) formation in chemoresistant ovarian cancer cells (SKOV3, C200). We found that suppressing the mTOR pathway using either everolimus or metformin led to suppression of TNT formation in vitro, verifying TNTs as a potential target for cancer-directed therapy. Additionally, TNT formation was detected in co-cultures including between platinum-resistant SKOV3 cells, between SKOV3 cells and platinum-chemosensitive A2780 cells, and between SKOV3 cells cultured with benign ovarian epithelial (IOSE) cells; these findings indicate that TNTs are novel conduits for malignant cell interactions and tumor cell interactions with other cells in the microenvironment. When chemoresistant C200 and parent chemosensitive A2780 cells were co-cultured, chemoresistant cells displayed a higher likelihood of TNT formation to each other than to chemosensitive malignant or benign epithelial cells. Hypoxia-induced TNT formation represents a potential mechanism for intercellular communication in ovarian cancer and other forms of invasive refractory cancers. PMID:27223082

  8. Control of cell fate by the formation of an architecturally complex bacterial community

    PubMed Central

    Vlamakis, Hera; Aguilar, Claudio; Losick, Richard; Kolter, Roberto

    2008-01-01

    Bacteria form architecturally complex communities known as biofilms in which cells are held together by an extracellular matrix. Biofilms harbor multiple cell types, and it has been proposed that within biofilms individual cells follow different developmental pathways, resulting in heterogeneous populations. Here we demonstrate cellular differentiation within biofilms of the spore-forming bacterium Bacillus subtilis, and present evidence that formation of the biofilm governs differentiation. We show that motile, matrix-producing, and sporulating cells localize to distinct regions within the biofilm, and that the localization and percentage of each cell type is dynamic throughout development of the community. Importantly, mutants that do not produce extracellular matrix form unstructured biofilms that are deficient in sporulation. We propose that sporulation is a culminating feature of biofilm formation, and that spore formation is coupled to the formation of an architecturally complex community of cells. PMID:18381896

  9. Ada in AI or AI in Ada. On developing a rationale for integration

    NASA Technical Reports Server (NTRS)

    Collard, Philippe E.; Goforth, Andre

    1988-01-01

    The use of Ada as an Artificial Intelligence (AI) language is gaining interest in the NASA Community, i.e., by parties who have a need to deploy Knowledge Based-Systems (KBS) compatible with the use of Ada as the software standard for the Space Station. A fair number of KBS and pseudo-KBS implementations in Ada exist today. Currently, no widely used guidelines exist to compare and evaluate these with one another. The lack of guidelines illustrates a fundamental problem inherent in trying to compare and evaluate implementations of any sort in languages that are procedural or imperative in style, such as Ada, with those in languages that are functional in style, such as Lisp. Discussed are the strengths and weakness of using Ada as an AI language and a preliminary analysis provided of factors needed for the development of criteria for the integration of these two families of languages and the environments in which they are implemented. The intent for developing such criteria is to have a logical rationale that may be used to guide the development of Ada tools and methodology to support KBS requirements, and to identify those AI technology components that may most readily and effectively be deployed in Ada.

  10. Pedagogy and the PC: Trends in the AIS Curriculum

    ERIC Educational Resources Information Center

    Badua, Frank

    2008-01-01

    The author investigated the array of course topics in accounting information systems (AIS), as course syllabi embody. The author (a) used exploratory data analysis to determine the topics that AIS courses most frequently offered and (b) used descriptive statistics and econometric analysis to trace the diversity of course topics through time,…

  11. Integrating the Wall Street Journal into AIS Courses

    ERIC Educational Resources Information Center

    Kohlmeyer, James M., III

    2008-01-01

    While it is important for accounting information systems (AIS) students to understand computer technology, internal controls and business processes, such knowledge is of little use without reference to appropriate contexts. Integrating Wall Street Journal (WSJ) readings and discussions into AIS classes can enrich learning by stimulating…

  12. An Immune Agent for Web-Based AI Course

    ERIC Educational Resources Information Center

    Gong, Tao; Cai, Zixing

    2006-01-01

    To overcome weakness and faults of a web-based e-learning course such as Artificial Intelligence (AI), an immune agent was proposed, simulating a natural immune mechanism against a virus. The immune agent was built on the multi-dimension education agent model and immune algorithm. The web-based AI course was comprised of many files, such as HTML…

  13. Cell-size distribution in epithelial tissue formation and homeostasis.

    PubMed

    Puliafito, Alberto; Primo, Luca; Celani, Antonio

    2017-03-01

    How cell growth and proliferation are orchestrated in living tissues to achieve a given biological function is a central problem in biology. During development, tissue regeneration and homeostasis, cell proliferation must be coordinated by spatial cues in order for cells to attain the correct size and shape. Biological tissues also feature a notable homogeneity of cell size, which, in specific cases, represents a physiological need. Here, we study the temporal evolution of the cell-size distribution by applying the theory of kinetic fragmentation to tissue development and homeostasis. Our theory predicts self-similar probability density function (PDF) of cell size and explains how division times and redistribution ensure cell size homogeneity across the tissue. Theoretical predictions and numerical simulations of confluent non-homeostatic tissue cultures show that cell size distribution is self-similar. Our experimental data confirm predictions and reveal that, as assumed in the theory, cell division times scale like a power-law of the cell size. We find that in homeostatic conditions there is a stationary distribution with lognormal tails, consistently with our experimental data. Our theoretical predictions and numerical simulations show that the shape of the PDF depends on how the space inherited by apoptotic cells is redistributed and that apoptotic cell rates might also depend on size.

  14. Formate: an Energy Storage and Transport Bridge between Carbon Dioxide and a Formate Fuel Cell in a Single Device.

    PubMed

    Vo, Tracy; Purohit, Krutarth; Nguyen, Christopher; Biggs, Brenna; Mayoral, Salvador; Haan, John L

    2015-11-01

    We demonstrate the first device to our knowledge that uses a solar panel to power the electrochemical reduction of dissolved carbon dioxide (carbonate) into formate that is then used in the same device to operate a direct formate fuel cell (DFFC). The electrochemical reduction of carbonate is carried out on a Sn electrode in a reservoir that maintains a constant carbon balance between carbonate and formate. The electron-rich formate species is converted by the DFFC into electrical energy through electron release. The product of DFFC operation is the electron-deficient carbonate species that diffuses back to the reservoir bulk. It is possible to continuously charge the device using alternative energy (e.g., solar) to convert carbonate to formate for on-demand use in the DFFC; the intermittent nature of alternative energy makes this an attractive design. In this work, we demonstrate a proof-of-concept device that performs reduction of carbonate, storage of formate, and operation of a DFFC.

  15. Doctor AI: Predicting Clinical Events via Recurrent Neural Networks

    PubMed Central

    Choi, Edward; Bahadori, Mohammad Taha; Schuetz, Andy; Stewart, Walter F.; Sun, Jimeng

    2017-01-01

    Leveraging large historical data in electronic health record (EHR), we developed Doctor AI, a generic predictive model that covers observed medical conditions and medication uses. Doctor AI is a temporal model using recurrent neural networks (RNN) and was developed and applied to longitudinal time stamped EHR data from 260K patients over 8 years. Encounter records (e.g. diagnosis codes, medication codes or procedure codes) were input to RNN to predict (all) the diagnosis and medication categories for a subsequent visit. Doctor AI assesses the history of patients to make multilabel predictions (one label for each diagnosis or medication category). Based on separate blind test set evaluation, Doctor AI can perform differential diagnosis with up to 79% recall@30, significantly higher than several baselines. Moreover, we demonstrate great generalizability of Doctor AI by adapting the resulting models from one institution to another without losing substantial accuracy. PMID:28286600

  16. Effects of irradiated biodegradable polymer in endothelial cell monolayer formation

    NASA Astrophysics Data System (ADS)

    Arbeitman, Claudia R.; del Grosso, Mariela F.; Behar, Moni; García Bermúdez, Gerardo

    2013-11-01

    In this work we study cell adhesion, proliferation and cell morphology of endothelial cell cultured on poly-L-lactide acid (PLLA) modified by heavy ion irradiation. Thin films of PLLA samples were irradiated with sulfur (S) at energies of 75 MeV and gold (Au) at 18 MeV ion-beams. Ion beams were provided by the Tandar (Buenos Aires, Argentina) and Tandetron (Porto Alegre, Brazil) accelerators, respectively. The growth of a monolayer of bovine aortic endothelial cells (BAEC) onto unirradiated and irradiated surfaces has been studied by in vitro techniques in static culture. Cell viability and proliferation increased on modified substrates. But the results on unirradiated samples, indicate cell death (necrosis/apoptosis) with the consequent decrease in proliferation. We analyzed the correlation between irradiation parameters and cell metabolism and morphology.

  17. Stem cells catalyze cartilage formation by neonatal articular chondrocytes in 3D biomimetic hydrogels

    NASA Astrophysics Data System (ADS)

    Lai, Janice H.; Kajiyama, Glen; Smith, Robert Lane; Maloney, William; Yang, Fan

    2013-12-01

    Cartilage loss is a leading cause of disability among adults and effective therapy remains elusive. Neonatal chondrocytes (NChons) are an attractive allogeneic cell source for cartilage repair, but their clinical translation has been hindered by scarce donor availability. Here we examine the potential for catalyzing cartilage tissue formation using a minimal number of NChons by co-culturing them with adipose-derived stem cells (ADSCs) in 3D hydrogels. Using three different co-culture models, we demonstrated that the effects of co-culture on cartilage tissue formation are dependent on the intercellular distance and cell distribution in 3D. Unexpectedly, increasing ADSC ratio in mixed co-culture led to increased synergy between NChons and ADSCs, and resulted in the formation of large neocartilage nodules. This work raises the potential of utilizing stem cells to catalyze tissue formation by neonatal chondrocytes via paracrine signaling, and highlights the importance of controlling cell distribution in 3D matrices to achieve optimal synergy.

  18. On the formation of germ cells: The good, the bad and the ugly.

    PubMed

    Chuva de Sousa Lopes, Susana M; Roelen, Bernard A J

    2010-03-01

    Mammalian germ cells are powerful cells, the only ones that transmit information to the next generation ensuring the continuation of the species. But "with great power, comes great responsibility", meaning that germ cells are only a few steps away from turning carcinogenic. Despite recent advances little is known about germ cell formation in mammals, predominantly because of the inaccessibility of these cells. Moreover, it is difficult to pin down what in essence is characteristic of a germ cell, as germ cells keep changing place, morphology, expression markers and epigenetic identity. Formation of (primordial) germ cells in primate ES cell cultures would therefore be helpful to identify molecular signalling pathways associated with germ cell differentiation and to study epigenetic changes in germ cells. In addition, the in vitro derivation of functional germ cells from ES cells could be used in combination with therapeutic cloning to generate patient-specific ES cell lines, and can have applications in animal breeding. In this review we present the state-of-the-art on how mouse and human germ cells are formed in vivo (the good), we discuss the link between germ cells, pluripotency and germ cell tumours (the bad) and show that despite continuous progress in trying to differentiate germ cells in vitro (the ugly) the generation of functional germ cells is still a real challenge.

  19. Apolipoprotein A-I Helsinki promotes intracellular acyl-CoA cholesterol acyltransferase (ACAT) protein accumulation.

    PubMed

    Toledo, Juan D; Garda, Horacio A; Cabaleiro, Laura V; Cuellar, Angela; Pellon-Maison, Magali; Gonzalez-Baro, Maria R; Gonzalez, Marina C

    2013-05-01

    Reverse cholesterol transport is a process of high antiatherogenic relevance in which apolipoprotein AI (apoA-I) plays an important role. The interaction of apoA-I with peripheral cells produces through mechanisms that are still poorly understood the mobilization of intracellular cholesterol depots toward plasma membrane. In macrophages, these mechanisms seem to be related to the modulation of the activity of acyl-CoA cholesterol acyltransferase (ACAT), the enzyme responsible for the intracellular cholesterol ester biosynthesis that is stored in lipid droplets. The activation of ACAT and the accumulation of lipid droplets play a key role in the transformation of macrophages into foam cells, leading to the formation of atheroma or atherosclerotic plaque. ApoA-I Helsinki (or ∆K107) is a natural apoA-I variant with a lysine deletion in the central protein region, carriers of which have increased atherosclerosis risk. We herein show that treatment of cultured RAW macrophages or CHOK1 cells with ∆K107, but not with wild-type apoA-I or a variant containing a similar deletion at the C-terminal region (∆K226), lead to a marked increase (more than 10 times) in the intracellular ACAT1 protein level as detected by western blot analysis. However, we could only detect a slight increase in cholesteryl ester produced by ∆K107 mainly when Chol loading was supplied by low-density lipoprotein (LDL). Although a similar choline-phospholipid efflux is evoked by these apoA-I variants, the change in phosphatidylcholine/sphyngomyelin distribution produced by wild-type apoA-I is not observed with either ∆K107 or ∆K226.

  20. Long non-coding RNA LOC283070 mediates the transition of LNCaP cells into androgen-independent cells possibly via CAMK1D

    PubMed Central

    Wang, Lina; Lin, Yani; Meng, Hui; Liu, Chunyan; Xue, Jing; Zhang, Qi; Li, Chaoyang; Zhang, Pengju; Cui, Fuai; Chen, Weiwen; Jiang, Anli

    2016-01-01

    Aims: The present study is to investigate the role of long non-coding RNAs (lncRNAs) in the development of androgen independence in prostate cancer and its underlying mechanism. Methods: We established an androgen-independent prostate carcinoma (AIPC) cell line LNCaP-AI from androgen-dependent prostate carcinoma (ADPC) cell line LNCaP. Different expression profiles of lncRNAs and mRNAs between LNCaP and LNCaP-AI cells were investigated using microarray analysis. The expression of RNAs was determined using quantitative real-time polymerase chain reaction. Protein levels were measured using Western blotting. MTT assay was used to test cell viability. Tumor formation assay was performed in nude mice to detect tumor growth in vivo. Flow cytometry was performed to detect cell cycles. Transwell assay was employed to test cell migration and invasion. Results: According to bioinformatics prediction, lncRNA LOC283070 could possibly play an important role in the transition of LNCaP cells into LNCaP-AI cells. LOC283070 was up-regulated in LNCaP-AI cells and frequently up-regulated in AIPC cell lines. Overexpression of LOC283070 in LNCaP cells accelerated cell proliferation and migration, even under androgen-independent circumstances. Knockdown of LOC283070 inhibited LNCaP-AI cell proliferation and migration. Moreover, overexpression of LOC283070 promoted tumor growth in vivo in both normal mice and castrated mice. CAMK1D overexpression had similar effect with LOC283070, and CAMK1D knockdown fully abrogated the effect of LOC283070 overexpression on the transition of LNCaP cells into androgen-independent cells. Conclusions: The present study shows that overexpression of LOC283070 mediates the transition of LNCaP cells into androgen-independent LNCaP-AI cells possibly via CAMK1D. PMID:28077997

  1. Nicotinate-Curcumin Impedes Foam Cell Formation from THP-1 Cells through Restoring Autophagy Flux

    PubMed Central

    Gu, Hong-Feng; Li, Hai-Zhe; Tang, Ya-Ling; Tang, Xiao-Qing; Zheng, Xi-Long; Liao, Duan-Fang

    2016-01-01

    Our previous studies have indicated that a novel curcumin derivate nicotinate-curcumin (NC) has beneficial effects on the prevention of atherosclerosis, but the precise mechanisms are not fully understood. Given that autophagy regulates lipid metabolism, the present study was designed to investigate whether NC decreases foam cell formation through restoring autophagy flux in oxidized low-density lipoprotein (ox-LDL)-treated THP-1 cells. Our results showed that ox-LDL (100 μg/ml) was accumulated in THP-1 cells and impaired autophagy flux. Ox-LDL-induced impairment of autophagy was enhanced by treatment with the autophagy inhibitor chloroquine (CQ) and rescued by the autophagy inducer rapamycin. The aggregation of ox-LDL was increased by CQ, but decreased by rapamycin. In addition, colocalization of lipid droplets with LC3-II was remarkably reduced in ox-LDL group. In contrast, NC (10 μM) rescued the impaired autophagy flux by significantly increasing level of LC3-II, the number of autophagolysosomes, and the degradation of p62 in ox-LDL-treated THP-1 cells. Inhibition of the PI3K-Akt-mTOR signaling was required for NC-rescued autophagy flux. Notably, our results showed that NC remarkably promoted the colocalization of lipid droplets with autophagolysosomes, increased efflux of cholesterol, and reduced ox-LDL accumulation in THP-1 cells. However, treatment with 3-methyladenine (3-MA) or CQ reduced the protective effects of NC on lipid accumulation. Collectively, the findings suggest that NC decreases lipid accumulation in THP-1 cells through restoring autophagy flux, and further implicate that NC may be a potential therapeutic reagent to reverse atherosclerosis. PMID:27128486

  2. Mesenchymal stem cells injection in degenerated intervertebral disc: cell leakage may induce osteophyte formation.

    PubMed

    Vadalà, Gianluca; Sowa, Gwendolyn; Hubert, Mark; Gilbertson, Lars G; Denaro, Vincenzo; Kang, James D

    2012-05-01

    Recent studies have shown that mesenchymal stem cell (MSC)-based therapy might be an effective approach for the treatment of intervertebral disc degeneration (IDD). However, many unanswered questions remain before clinical translation, such as the most effective stem cell type, a reliable transplantation method, including the carrier choice, and the fate of stem cells after misdirected delivery, among others. The objective of the study was to evaluate the fate and effect of allogenic bone marrow MSCs after transplantation into an IDD model. The L2-3, L3-4 and L4-5 intervertebral discs (IVDs) of four rabbits were stabbed to create IDD. Rabbit MSCs were expanded in vitro and in part transduced with retrovirus/eGFP. After 3 weeks, 1 × 10(5) MSCs were injected into the IVDs. The rabbits were followed by X-ray and MRI 3 and 9 weeks after injection. Then the animals were sacrificed and the spines analysed histologically. MRI showed no signs of regeneration. X-ray and gross anatomy inspection demonstrated large anterolateral osteophytes. Histological analysis showed that the osteophytes were composed of mineralized tissue surrounded by chondrocytes, with the labelled MSCs among the osteophyte-forming cells. The labelled MSCs were not found in the nucleus. Inflammatory cells were not observed in any injected IVDs. These results raise concern that MSCs can migrate out of the nucleus and undesirable bone formation may occur. While cause cannot be inferred from this study, the presence of MSCs in the osteophytes suggests a potential side-effect with this approach. IVD regeneration strategies need to focus on cell carrier systems and annulus-sealing technologies to avoid pitfalls.

  3. Sodium formate induces autophagy and apoptosis via the JNK signaling pathway of photoreceptor cells.

    PubMed

    Wang, Ying; Xu, Shao-Lin; Xu, Wen-Jing; Yang, Hai-Yan; Hu, Ping; Li, Yu-Xin

    2016-02-01

    Incidents associated with methanol intoxication resulting from the consumption of fake wine occur not infrequently worldwide. Certain individuals are made blind due to methanol poisoning. The present study aimed to investigate the effects of sodium formate exposure on photoreceptor cells (661W cells). The 661W cells were exposed to sodium formate for 6‑24 h and cell viability was determined using a 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyl‑2H‑tetrazolium bromide (MTT) assay. Subsequently, the 661W cells were exposed to 15 or 30 mM sodium formate for 24 h. The level of apoptosis was determined using Hoechst 33342/propidium iodide staining, visualizing the cells under a fluorescence microscope, and annexin V‑fluorescein isothiocyanate staining, using flow cytometric analysis. Intracellular reactive oxygen species (ROS) were measured using 2',7'‑dichlorofluorescein diacetate (DCFH‑DA) staining, followed by flow cytometric analysis. Autophagy of the 661W cells was measured by monodansylcadaverine staining. The activation of phosphorylated c‑Jun N‑terminal kinase (p‑JNK), B‑cell lymphoma (Bcl‑2), Bcl‑2‑associated X protein, cleaved caspase‑3, cleaved caspase‑9 and microtubule‑associated protein 1A/1B‑light chain 3 (LC3) was assessed by western blotting. The effects of Z‑VAD‑fmk (a pan‑caspase inhibitor) and SP600125 (a JNK inhibitor) on the viability of the sodium formate‑induced 661W cells were determined using an MTT assay. Sodium formate treatment induced a decrease in the viability of the 661W cells in a time‑ and a dose‑dependent manner. In addition, sodium formate at concentrations of 15 or 30 mM markedly increased the level of apoptosis and the ROS levels, as measured by DCFH‑DA staining of the 661W cells. Additionally, 661W cells exposed to sodium formate for 24 h exhibited increased levels of p‑JNK, Bax, cleaved caspase‑3, cleaved caspase‑9 and LC3II (the phosphatidylethanolamine‑modified form

  4. The muscle satellite cell at 50: the formative years

    PubMed Central

    2011-01-01

    In February 1961, Alexander Mauro described a cell 'wedged' between the plasma membrane of the muscle fibre and the surrounding basement membrane. He postulated that it could be a dormant myoblast, poised to repair muscle when needed. In the same month, Bernard Katz also reported a cell in a similar location on muscle spindles, suggesting that it was associated with development and growth of intrafusal muscle fibres. Both Mauro and Katz used the term 'satellite cell' in relation to their discoveries. Today, the muscle satellite cell is widely accepted as the resident stem cell of skeletal muscle, supplying myoblasts for growth, homeostasis and repair. Since 2011 marks both the 50th anniversary of the discovery of the satellite cell, and the launch of Skeletal Muscle, it seems an opportune moment to summarise the seminal events in the history of research into muscle regeneration. We start with the 19th-century pioneers who showed that muscle had a regenerative capacity, through to the descriptions from the mid-20th century of the underlying cellular mechanisms. The journey of the satellite cell from electron microscope curio, to its gradual acceptance as a bona fide myoblast precursor, is then charted: work that provided the foundations for our understanding of the role of the satellite cell. Finally, the rapid progress in the age of molecular biology is briefly discussed, and some ongoing debates on satellite cell function highlighted. PMID:21849021

  5. Programmed cell death for defense against anomaly and tumor formation

    SciTech Connect

    Kondo, Sohei; Norimura, Toshiyuki; Nomura, Taisei

    1995-12-31

    Cell death after exposure to low-level radiation is often considered evidence that radiation is poisonous, however small the dose. Evidence has been accumulating to support the notion that cell death after low-level exposure to radiation results from activation of suicidal genes {open_quote}programmed cell death{close_quote} or {open_quote}apoptosis{close_quote} - for the health of the whole body. This paper gives experimental evidence that embryos of fruit flies and mouse fetuses have potent defense mechanisms against teratogenic or tumorigenic injury caused by radiation and carcinogens, which function through programmed cell death.

  6. Human NK cell development requires CD56-mediated motility and formation of the developmental synapse

    PubMed Central

    Mace, Emily M.; Gunesch, Justin T.; Dixon, Amera; Orange, Jordan S.

    2016-01-01

    While distinct stages of natural killer (NK) cell development have been defined, the molecular interactions that shape human NK cell maturation are poorly understood. Here we define intercellular interactions between developing NK cells and stromal cells which, through contact-dependent mechanisms, promote the generation of mature, functional human NK cells from CD34+ precursors. We show that developing NK cells undergo unique, developmental stage-specific sustained and transient interactions with developmentally supportive stromal cells, and that the relative motility of NK cells increases as they move through development in vitro and ex vivo. These interactions include the formation of a synapse between developing NK cells and stromal cells, which we term the developmental synapse. Finally, we identify a role for CD56 in developmental synapse structure, NK cell motility and NK cell development. Thus, we define the developmental synapse leading to human NK cell functional maturation. PMID:27435370

  7. Identification of poultry meat-derived fatty acids functioning as quorum sensing signal inhibitors of autoinducer-2 (AI-2)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Autoinducer-2 (AI-2) is a compound that plays a key role in bacterial cell-to-cell communication (quorum sensing). Previous research has shown certain food matrices inhibit this signaling compound. Using the reporter strain, Vibrio harveyi BB170, quorum sensing inhibitors contained in poultry meat...

  8. Raman scattering evidence of hydrohalite formation on frozen yeast cells.

    PubMed

    Okotrub, K A; Surovtsev, N V

    2013-02-01

    We studied yeast cells in physiological solution during freezing by Raman microspectroscopy technique. The purpose was to find out the origin of a sharp peak near ∼3430cm(-1) in Raman spectrum of frozen mammalian cells, observed earlier (J. Dong et al., Biophys. J. 99 (2010) 2453), which presumably could be used as an indicator of intracellar ice appearance. We have shown that this line (actually doublet of 3408 and 3425cm(-1)) corresponds to Raman spectrum of hydrohalite (NaCl⋅2H(2)O), which is formed as the result of the eutectic crystallization of the liquid solution around the cells. We also show that the spatial distribution of hydrohalite in the sample significantly depends on the cooling rate. At lower cooling rate (1°C/min), products of eutectic crystallization form layer on the cell surface which thickness varies for different cells and can reach ∼1μm in thickness. At higher cooling rate (20°C/min), the hydrohalite distribution appears more homogeneous, in the sample, and the eutectic crystallization layer around the cells was estimated to be less than ∼20nm. These experimental results are consistent with scenarios predicted by the two-factor hypothesis for freezing induced cell injury. This work demonstrates a potential of Raman microspectroscopy to study peculiarities of the eutectic crystallization around single cells in vivo with the high spatial resolution.

  9. Robust optimization of a mathematical model to design a dynamic cell formation problem considering labor utilization

    NASA Astrophysics Data System (ADS)

    Vafaeinezhad, Moghadaseh; Kia, Reza; Shahnazari-Shahrezaei, Parisa

    2016-11-01

    Cell formation (CF) problem is one of the most important decision problems in designing a cellular manufacturing system includes grouping machines into machine cells and parts into part families. Several factors should be considered in a cell formation problem. In this work, robust optimization of a mathematical model of a dynamic cell formation problem integrating CF, production planning and worker assignment is implemented with uncertain scenario-based data. The robust approach is used to reduce the effects of fluctuations of the uncertain parameters with regards to all possible future scenarios. In this research, miscellaneous cost parameters of the cell formation and demand fluctuations are subject to uncertainty and a mixed-integer nonlinear programming model is developed to formulate the related robust dynamic cell formation problem. The objective function seeks to minimize total costs including machine constant, machine procurement, machine relocation, machine operation, inter-cell and intra-cell movement, overtime, shifting labors between cells and inventory holding. Finally, a case study is carried out to display the robustness and effectiveness of the proposed model. The tradeoff between solution robustness and model robustness is also analyzed in the obtained results.

  10. Laser-based techniques for living cell pattern formation

    NASA Astrophysics Data System (ADS)

    Hopp, Béla; Smausz, Tomi; Papdi, Bence; Bor, Zsolt; Szabó, András; Kolozsvári, Lajos; Fotakis, Costas; Nógrádi, Antal

    2008-10-01

    In the production of biosensors or artificial tissues a basic step is the immobilization of living cells along the required pattern. In this paper the ability of some promising laser-based methods to influence the interaction between cells and various surfaces is presented. In the first set of experiments laser-induced patterned photochemical modification of polymer foils was used to achieve guided adherence and growth of cells to the modified areas: (a) Polytetrafluoroethylene was irradiated with ArF excimer laser ( λ=193 nm, FWHM=20 ns, F=9 mJ/cm2) in presence of triethylene tetramine liquid photoreagent; (b) a thin carbon layer was produced by KrF excimer laser ( λ=248 nm, FWHM=30 ns, F=35 mJ/cm2) irradiation on polyimide surface to influence the cell adherence. It was found that the incorporation of amine groups in the PTFE polymer chain instead of the fluorine atoms can both promote and prevent the adherence of living cells (depending on the applied cell types) on the treated surfaces, while the laser generated carbon layer on polyimide surface did not effectively improve adherence. Our attempts to influence the cell adherence by morphological modifications created by ArF laser irradiation onto polyethylene terephtalate surface showed a surface roughness dependence. This method was effective only when the Ra roughness parameter of the developed structure did not exceed the 0.1 micrometer value. Pulsed laser deposition with femtosecond KrF excimer lasers ( F=2.2 J/cm2) was effectively used to deposit structured thin films from biomaterials (endothelial cell growth supplement and collagen embedded in starch matrix) to promote the adherence and growth of cells. These results present evidence that some surface can be successfully altered to induce guided cell growth.

  11. VE-cadherin interacts with cell polarity protein Pals1 to regulate vascular lumen formation.

    PubMed

    Brinkmann, Benjamin F; Steinbacher, Tim; Hartmann, Christian; Kummer, Daniel; Pajonczyk, Denise; Mirzapourshafiyi, Fatemeh; Nakayama, Masanori; Weide, Thomas; Gerke, Volker; Ebnet, Klaus

    2016-09-15

    Blood vessel tubulogenesis requires the formation of stable cell-to-cell contacts and the establishment of apicobasal polarity of vascular endothelial cells. Cell polarity is regulated by highly conserved cell polarity protein complexes such as the Par3-aPKC-Par6 complex and the CRB3-Pals1-PATJ complex, which are expressed by many different cell types and regulate various aspects of cell polarity. Here we describe a functional interaction of VE-cadherin with the cell polarity protein Pals1. Pals1 directly interacts with VE-cadherin through a membrane-proximal motif in the cytoplasmic domain of VE-cadherin. VE-cadherin clusters Pals1 at cell-cell junctions. Mutating the Pals1-binding motif in VE-cadherin abrogates the ability of VE-cadherin to regulate apicobasal polarity and vascular lumen formation. In a similar way, deletion of the Par3-binding motif at the C-terminus of VE-cadherin impairs apicobasal polarity and vascular lumen formation. Our findings indicate that the biological activity of VE-cadherin in regulating endothelial polarity and vascular lumen formation is mediated through its interaction with the two cell polarity proteins Pals1 and Par3.

  12. A Theoretical Model of Jigsaw-Puzzle Pattern Formation by Plant Leaf Epidermal Cells

    PubMed Central

    Higaki, Takumi; Kutsuna, Natsumaro; Akita, Kae; Takigawa-Imamura, Hisako; Yoshimura, Kenji; Miura, Takashi

    2016-01-01

    Plant leaf epidermal cells exhibit a jigsaw puzzle–like pattern that is generated by interdigitation of the cell wall during leaf development. The contribution of two ROP GTPases, ROP2 and ROP6, to the cytoskeletal dynamics that regulate epidermal cell wall interdigitation has already been examined; however, how interactions between these molecules result in pattern formation remains to be elucidated. Here, we propose a simple interface equation model that incorporates both the cell wall remodeling activity of ROP GTPases and the diffusible signaling molecules by which they are regulated. This model successfully reproduces pattern formation observed in vivo, and explains the counterintuitive experimental results of decreased cellulose production and increased thickness. Our model also reproduces the dynamics of three-way cell wall junctions. Therefore, this model provides a possible mechanism for cell wall interdigitation formation in vivo. PMID:27054467

  13. CD22 is required for formation of memory B cell precursors within germinal centers

    PubMed Central

    Chappell, Craig P.; Draves, Kevin E.

    2017-01-01

    CD22 is a BCR co-receptor that regulates B cell signaling, proliferation and survival and is required for T cell-independent Ab responses. To investigate the role of CD22 during T cell-dependent (TD) Ab responses and memory B cell formation, we analyzed Ag-specific B cell responses generated by wild-type (WT) or CD22-/- B cells following immunization with a TD Ag. CD22-/- B cells mounted normal early Ab responses yet failed to generate either memory B cells or long-lived plasma cells, whereas WT B cells formed both populations. Surprisingly, B cell expansion and germinal center (GC) differentiation were comparable between WT and CD22-/- B cells. CD22-/- B cells, however, were significantly less capable of generating a population of CXCR4hiCD38hi GC B cells, which we propose represent memory B cell precursors within GCs. These results demonstrate a novel role for CD22 during TD humoral responses evident during primary GC formation and underscore that CD22 functions not only during B cell maturation but also during responses to both TD and T cell-independent antigens. PMID:28346517

  14. Functional Anatomy of T Cell Activation and Synapse Formation

    PubMed Central

    Fooksman, David R.; Vardhana, Santosh; Vasiliver-Shamis, Gaia; Liese, Jan; Blair, David; Waite, Janelle; Sacristán, Catarina; Victora, Gabriel; Zanin-Zhorov, Alexandra; Dustin, Michael L.

    2010-01-01

    T cell activation and function require a structured engagement of antigen-presenting cells. These cell contacts are characterized by two distinct dynamics in vivo: transient contacts resulting from promigratory junctions called immunological kinapses or prolonged contacts from stable junctions called immunological synapses. Kinapses operate in the steady state to allow referencing to self-peptide-MHC (pMHC) and searching for pathogen-derived pMHC. Synapses are induced by T cell receptor (TCR) interactions with agonist pMHC under specific conditions and correlate with robust immune responses that generate effector and memory T cells. High-resolution imaging has revealed that the synapse is highly coordinated, integrating cell adhesion, TCR recognition of pMHC complexes, and an array of activating and inhibitory ligands to promote or prevent T cell signaling. In this review, we examine the molecular components, geometry, and timing underlying kinapses and synapses. We integrate recent molecular and physiological data to provide a synthesis and suggest ways forward. PMID:19968559

  15. Mechanisms underlying the formation of induced pluripotent stem cells.

    PubMed

    González, Federico; Huangfu, Danwei

    2016-01-01

    Human pluripotent stem cells (hPSCs) offer unique opportunities for studying human biology, modeling diseases, and therapeutic applications. The simplest approach so far to generate human PSC lines is through reprogramming of somatic cells from an individual by defined factors, referred to simply as reprogramming. Reprogramming circumvents the ethical controversies associated with human embryonic stem cells (hESCs) and nuclear transfer hESCs (nt-hESCs), and the resulting induced pluripotent stem cells (hiPSCs) retain the same basic genetic makeup as the somatic cell used for reprogramming. Since the first report of iPSCs by Takahashi and Yamanaka (Cell 2006, 126:663-676), the molecular mechanisms of reprogramming have been extensively investigated. A better mechanistic understanding of reprogramming is fundamental not only to iPSC biology and improving the quality of iPSCs for therapeutic use, but also to our understanding of the molecular basis of cell identity, pluripotency, and plasticity. Here, we summarize the genetic, epigenetic, and cellular events during reprogramming, and the roles of various factors identified thus far in the reprogramming process. WIREs Dev Biol 2016, 5:39-65. doi: 10.1002/wdev.206 For further resources related to this article, please visit the WIREs website.

  16. Trunk neural crest cells: formation, migration and beyond.

    PubMed

    Vega-Lopez, Guillermo A; Cerrizuela, Santiago; Aybar, Manuel J

    2017-01-01

    Neural crest cells (NCCs) are a multipotent, migratory cell population that generates an astonishingly diverse array of cell types during vertebrate development. The trunk neural crest has long been considered of particular significance. First, it has been held that the trunk neural crest has a morphogenetic role, acting to coordinate the development of the peripheral nervous system, secretory cells of the endocrine system and pigment cells of the skin. Second, the trunk neural crest additionally has skeletal potential. However, it has been demonstrated that a key role of the trunk neural crest streams is to organize the innervation of the intestine. Although trunk NCCs have a limited capacity for self-renewal, sometimes they become neural-crest-derived tumor cells and reveal the fact that that NCCs and tumor cells share the same molecular machinery. In this review we describe the routes taken by trunk NCCs and consider the signals and cues that pattern these trajectories. We also discuss recent advances in the characterization of the properties of trunk NCCs for various model organisms in order to highlight common themes. Finally, looking to the future, we discuss the need to translate the wealth of data from animal studies to the clinical area in order to develop treatments for neural crest-related human diseases.

  17. Parameters influencing AIS 1 neck injury outcome in frontal impacts.

    PubMed

    Jakobsson, Lotta; Norin, Hans; Svensson, Mats Y

    2004-06-01

    In order to gain more knowledge of the neck injury scenario in frontal impacts, a statistical study of parameters influencing incidences of AIS 1 neck injuries was performed. The data set consisted of 616 occupants in Volvo cars. Information regarding the crash, the safety systems, occupant characteristics (including prior neck problems), behavior and sitting posture at the time of impact, and neck symptoms (including duration) was collected and analyzed. Occupant characteristics (mainly gender, weight, and age), kinematics (head impacts) and behavior at the time of impact were identified as the most prominent parameter areas with regard to AIS 1 neck injury outcome. Specifically, women had a significantly higher AIS 1 neck injury rate as compared to men, occupants under the age of 50 had a significantly higher AIS 1 neck injury rate as compared to those above 50 and occupants weighing less than 65 kg have a significantly higher AIS 1 neck injury rate than heavier occupants. Drivers stating that they impacted their head against a frontal interior structure had a significantly higher AIS 1 neck injury rate than those without head impact. Also, occupants who stated they had tensed their neck muscles at the time of impact, had a significantly higher AIS 1 neck injury rate as compared to occupants who did not. Occupant activities, such as tightly gripping the steering wheel or straightening their arms showed a significantly increased AIS 1 neck injury rate, indicating that occupant behavior at time of impact could be influential with respect to AIS 1 neck injury outcome. Also, occupants reporting prior neck problems had a higher rate of persistent symptoms (>1 year) but no difference with respect to passing symptoms (<3 months) as compared to those without prior neck problems. Additionally, there was no distinct pattern for the duration of neck symptoms.

  18. Inducible and Constitutive β-Galactosidase Formation in Cells Recovering from Protein Synthesis Inhibition1

    PubMed Central

    Soreq, Hermona; Kaplan, Ruth

    1971-01-01

    Inducible and constitutive β-galactosidase formation and radioactive amino acid incorporation were measured in cells recovering from various treatments which inhibit protein synthesis in the cell. Undelayed β-galactosidase formation was found in stringent auxotrophs recovering from amino acid starvation, in cells recovering from glycerol or potassium starvation, and in bacteria recovering from puromycin treatment. Delayed β-galactosidase formation was found in relaxed auxotrophs recovering from amino acid starvation and in prototrophs recovering from chloramphenicol or from tetracycline treatment. The length of this delay was directly proportional to the duration of the treatment. All cells recovering from the various treatments exhibited a slightly decreased rate of β-galactosidase formation and an increase in radioactive amino acid incorporation. PMID:4945186

  19. Colony formation and interleukin 2 production by leukaemic human T cells.

    PubMed Central

    Krajewski, A S; Dewar, A E; Seidelin, P H; Murray, R

    1983-01-01

    PHA-induced colony formation and interleukin 2 (IL-2) production were studied in four patients with T cell leukaemia (three cases OKT4+/T helper and one case OKT8+/T cytotoxic suppressor). Cases of T helper cell leukaemia showed colony formation that was comparable to normal purified blood T cells and was not dependent on the addition of conditioned medium, containing IL-2 activity, to cultures. In contrast the T suppressor cell leukaemia formed colonies only when cultures were supplemented with IL-2 containing medium. When IL-2 production by PHA stimulated cells was measured culture supernatants from the three T helper cell leukaemias all showed normal or high levels of activity, when compared to normal blood mononuclear cells, whereas the T suppressor cell leukaemia showed no activity. PMID:6604606

  20. Mechanical Model of Geometric Cell and Topological Algorithm for Cell Dynamics from Single-Cell to Formation of Monolayered Tissues with Pattern

    PubMed Central

    Kachalo, Sëma; Naveed, Hammad; Cao, Youfang; Zhao, Jieling; Liang, Jie

    2015-01-01

    Geometric and mechanical properties of individual cells and interactions among neighboring cells are the basis of formation of tissue patterns. Understanding the complex interplay of cells is essential for gaining insight into embryogenesis, tissue development, and other emerging behavior. Here we describe a cell model and an efficient geometric algorithm for studying the dynamic process of tissue formation in 2D (e.g. epithelial tissues). Our approach improves upon previous methods by incorporating properties of individual cells as well as detailed description of the dynamic growth process, with all topological changes accounted for. Cell size, shape, and division plane orientation are modeled realistically. In addition, cell birth, cell growth, cell shrinkage, cell death, cell division, cell collision, and cell rearrangements are now fully accounted for. Different models of cell-cell interactions, such as lateral inhibition during the process of growth, can be studied in detail. Cellular pattern formation for monolayered tissues from arbitrary initial conditions, including that of a single cell, can also be studied in detail. Computational efficiency is achieved through the employment of a special data structure that ensures access to neighboring cells in constant time, without additional space requirement. We have successfully generated tissues consisting of more than 20,000 cells starting from 2 cells within 1 hour. We show that our model can be used to study embryogenesis, tissue fusion, and cell apoptosis. We give detailed study of the classical developmental process of bristle formation on the epidermis of D. melanogaster and the fundamental problem of homeostatic size control in epithelial tissues. Simulation results reveal significant roles of solubility of secreted factors in both the bristle formation and the homeostatic control of tissue size. Our method can be used to study broad problems in monolayered tissue formation. Our software is publicly

  1. Numerical simulation of water transport and intracellular ice formation for freezing of endothelial cells.

    PubMed

    Zhao, G; Xu, Y; Ding, W P; Hu, M B

    2013-01-01

    Endothelial cell detachment may cause failure of blood vessel and corneal cryopreservation, and thus successful cryopreservation of endothelial cells is regarded to be the first step to optimize cryopreservation of endothelial cells containing tissues. In this study, the pre-determined biophysical parameters were incorporated into the model for intracellular ice formation (IIF) and the growth of intracellular ice crystals (ICG) to calculate cell water loss, supercooling of intracellular solution, intracellular ice formation and the growth of intracellular ice crystals. The optimal protocols were determined according to the combination effect of both solution injury and IIF injury.

  2. Bacterial lipopolysaccharide induces osteoclast formation in RAW 264.7 macrophage cells

    SciTech Connect

    Islam, Shamima; Hassan, Ferdaus; Tumurkhuu, Gantsetseg; Dagvadorj, Jargalsaikhan; Koide, Naoki; Naiki, Yoshikazu; Mori, Isamu; Yoshida, Tomoaki; Yokochi, Takashi . E-mail: yokochi@aichi-med-u.ac.jp

    2007-08-24

    Lipopolysaccharide (LPS) is a potent bone resorbing factor. The effect of LPS on osteoclast formation was examined by using murine RAW 264.7 macrophage cells. LPS-induced the formation of multinucleated giant cells (MGC) in RAW 264.7 cells 3 days after the exposure. MGCs were positive for tartrate-resistant acid phosphatase (TRAP) activity. Further, MGC formed resorption pits on calcium-phosphate thin film that is a substrate for osteoclasts. Therefore, LPS was suggested to induce osteoclast formation in RAW 264.7 cells. LPS-induced osteoclast formation was abolished by anti-tumor necrosis factor (TNF)-{alpha} antibody, but not antibodies to macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor (NF)-{kappa}B ligand (RANKL). TNF-{alpha} might play a critical role in LPS-induced osteoclast formation in RAW 264.7 cells. Inhibitors of NF-{kappa}B and stress activated protein kinase (SAPK/JNK) prevented the LPS-induced osteoclast formation. The detailed mechanism of LPS-induced osteoclast formation is discussed.

  3. VE-cadherin interacts with cell polarity protein Pals1 to regulate vascular lumen formation

    PubMed Central

    Brinkmann, Benjamin F.; Steinbacher, Tim; Hartmann, Christian; Kummer, Daniel; Pajonczyk, Denise; Mirzapourshafiyi, Fatemeh; Nakayama, Masanori; Weide, Thomas; Gerke, Volker; Ebnet, Klaus

    2016-01-01

    Blood vessel tubulogenesis requires the formation of stable cell-to-cell contacts and the establishment of apicobasal polarity of vascular endothelial cells. Cell polarity is regulated by highly conserved cell polarity protein complexes such as the Par3-aPKC-Par6 complex and the CRB3-Pals1-PATJ complex, which are expressed by many different cell types and regulate various aspects of cell polarity. Here we describe a functional interaction of VE-cadherin with the cell polarity protein Pals1. Pals1 directly interacts with VE-cadherin through a membrane-proximal motif in the cytoplasmic domain of VE-cadherin. VE-cadherin clusters Pals1 at cell–cell junctions. Mutating the Pals1-binding motif in VE-cadherin abrogates the ability of VE-cadherin to regulate apicobasal polarity and vascular lumen formation. In a similar way, deletion of the Par3-binding motif at the C-terminus of VE-cadherin impairs apicobasal polarity and vascular lumen formation. Our findings indicate that the biological activity of VE-cadherin in regulating endothelial polarity and vascular lumen formation is mediated through its interaction with the two cell polarity proteins Pals1 and Par3. PMID:27466317

  4. Differentiated cytoplasmic granule formation in quiescent and non-quiescent cells upon chronological aging

    PubMed Central

    Lee, Hsin-Yi; Cheng, Kuo-Yu; Chao, Jung-Chi; Leu, Jun-Yi

    2016-01-01

    Stationary phase cultures represent a complicated cell population comprising at least two different cell types, quiescent (Q) and non-quiescent (NQ) cells. Q and NQ cells have different lifespans and cell physiologies. However, less is known about the organization of cytosolic protein structures in these two cell types. In this study, we examined Q and NQ cells for the formation of several stationary phase-prevalent granule structures including actin bodies, proteasome storage granules, stress granules, P-bodies, the compartment for unconventional protein secretion (CUPS), and Hsp42-associated stationary phase granules (Hsp42-SPGs). Most of these structures preferentially form in NQ cells, except for Hsp42-SPGs, which are enriched in Q cells. When nutrients are provided, NQ cells enter mitosis less efficiently than Q cells, likely due to the time requirement for reorganizing some granule structures. We observed that heat shock-induced misfolded proteins often colocalize to Hsp42-SPGs, and Q cells clear these protein aggregates more efficiently, suggesting that Hsp42-SPGs may play an important role in the stress resistance of Q cells. Finally, we show that the cell fate of NQ cells is largely irreversible even if they are allowed to reenter mitosis. Our results reveal that the formation of different granule structures may represent the early stage of cell type differentiation in yeast stationary phase cultures. PMID:28357341

  5. Intact vinculin protein is required for control of cell shape, cell mechanics, and rac-dependent lamellipodia formation

    NASA Technical Reports Server (NTRS)

    Goldmann, Wolfgang H.; Ingber, Donald E.

    2002-01-01

    Studies were carried out using vinculin-deficient F9 embryonic carcinoma (gamma229) cells to analyze the relationship between structure and function within the focal adhesion protein vinculin, in the context of control of cell shape, cell mechanics, and movement. Atomic force microscopy studies revealed that transfection of the head (aa 1-821) or tail (aa 811-1066) domain of vinculin, alone or together, was unable to fully reverse the decrease in cell stiffness, spreading, and lamellipodia formation caused by vinculin deficiency. In contrast, replacement with intact vinculin completely restored normal cell mechanics and spreading regardless of whether its tyrosine phosphorylation site was deleted. Constitutively active rac also only induced extension of lamellipodia when microinjected into cells that expressed intact vinculin protein. These data indicate that vinculin's ability to physically couple integrins to the cytoskeleton, to mechanically stabilize cell shape, and to support rac-dependent lamellipodia formation all appear to depend on its intact three-dimensional structure.

  6. Quantum dot-based molecular imaging of cancer cell growth using a clone formation assay.

    PubMed

    Geng, Xia-Fei; Fang, Min; Liu, Shao-Ping; Li, Yan

    2016-10-01

    This aim of the present study was to investigate clonal growth behavior and analyze the proliferation characteristics of cancer cells. The MCF‑7 human breast cancer cell line, SW480 human colon cancer cell line and SGC7901 human gastric cancer cell line were selected to investigate the morphology of cell clones. Quantum dot‑based molecular targeted imaging techniques (which stained pan‑cytokeratin in the cytoplasm green and Ki67 in the cell nucleus yellow or red) were used to investigate the clone formation rate, cell morphology, discrete tendency, and Ki67 expression and distribution in clones. From the cell clone formation assay, the MCF‑7, SW480 and SGC7901 cells were observed to form clones on days 6, 8 and 12 of cell culture, respectively. These three types of cells had heterogeneous morphology, large nuclear:cytoplasmic ratios, and conspicuous pathological mitotic features. The cells at the clone periphery formed multiple pseudopodium. In certain clones, cancer cells at the borderline were separated from the central cell clusters or presented a discrete tendency. With quantum dot‑based molecular targeted imaging techniques, cells with strong Ki67 expression were predominantly shown to be distributed at the clone periphery, or concentrated on one side of the clones. In conclusion, cancer cell clones showed asymmetric growth behavior, and Ki67 was widely expressed in clones of these three cell lines, with strong expression around the clones, or aggregated at one side. Cell clone formation assay based on quantum dots molecular imaging offered a novel method to study the proliferative features of cancer cells, thus providing a further insight into tumor biology.

  7. Dynamics of vegetative cytoplasm during generative cell formation and pollen maturation in Arabidopsis thaliana

    NASA Technical Reports Server (NTRS)

    Kuang, A.; Musgrave, M. E.

    1996-01-01

    Ultrastructural changes of pollen cytoplasm during generative cell formation and pollen maturation in Arabidopsis thaliana were studied. The pollen cytoplasm develops a complicated ultrastructure and changes dramatically during these stages. Lipid droplets increase after generative cell formation and their organization and distribution change with the developmental stage. Starch grains in amyloplasts increase in number and size during generative and sperm cell formation and decrease at pollen maturity. The shape and membrane system of mitochondria change only slightly. Dictyosomes become very prominent, and numerous associated vesicles are observed during and after sperm cell formation. Endoplasmic reticulum appears extensively as stacks during sperm cell formation. Free and polyribosomes are abundant in the cytoplasm at all developmental stages although they appear denser at certain stages and in some areas. In mature pollen, all organelles are randomly distributed throughout the vegetative cytoplasm and numerous small particles appear. Organization and distribution of storage substances and appearance of these small particles during generative and sperm cell formation and pollen maturation are discussed.

  8. An Energy Dense-AI-NaBH4-PEMFC Based Power Generator for Unmanned Undersea Vehicles

    DTIC Science & Technology

    2016-03-01

    Florida Solar Energy Center Se. TASK NUMBER Sf. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION ...combination of polymer electrolyte membrane fuel cell (PEMFC) with a compact hydrogen generator util izing AI-NaBH4 composite fuel. The conditions...www.florldaenergycenter.org FINAL REPORT Contract Information Contract Number: Contract Title: Program Officer: PI: Organization : Email: Co

  9. Collagen-IV supported embryoid bodies formation and differentiation from buffalo (Bubalus bubalis) embryonic stem cells

    SciTech Connect

    Taru Sharma, G.; Dubey, Pawan K.; Verma, Om Prakash; Pratheesh, M.D.; Nath, Amar; Sai Kumar, G.

    2012-08-03

    Graphical abstract: EBs formation, characterization and expression of germinal layers marker genes of in vivo developed teratoma using four different types of extracellular matrices. Highlights: Black-Right-Pointing-Pointer Collagen-IV matrix is found cytocompatible for EBs formation and differentiation. Black-Right-Pointing-Pointer Established 3D microenvironment for ES cells development and differentiation into three germ layers. Black-Right-Pointing-Pointer Collagen-IV may be useful as promising candidate for ES cells based therapeutic applications. -- Abstract: Embryoid bodies (EBs) are used as in vitro model to study early extraembryonic tissue formation and differentiation. In this study, a novel method using three dimensional extracellular matrices for in vitro generation of EBs from buffalo embryonic stem (ES) cells and its differentiation potential by teratoma formation was successfully established. In vitro derived inner cell masses (ICMs) of hatched buffalo blastocyst were cultured on buffalo fetal fibroblast feeder layer for primary cell colony formation. For generation of EBs, pluripotent ES cells were seeded onto four different types of extracellular matrices viz; collagen-IV, laminin, fibronectin and matrigel using undifferentiating ES cell culture medium. After 5 days of culture, ESCs gradually grew into aggregates and formed simple EBs having circular structures. Twenty-six days later, they formed cystic EBs over collagen matrix with higher EBs formation and greater proliferation rate as compared to other extracellular matrices. Studies involving histological observations, fluorescence microscopy and RT-PCR analysis of the in vivo developed teratoma revealed that presence of all the three germ layer derivatives viz. ectoderm (NCAM), mesoderm (Flk-1) and endoderm (AFP). In conclusion, the method described here demonstrates a simple and cost-effective way of generating EBs from buffalo ES cells. Collagen-IV matrix was found cytocompatible as it

  10. Mechanosensitive store-operated calcium entry regulates the formation of cell polarity.

    PubMed

    Huang, Yi-Wei; Chang, Shu-Jing; I-Chen Harn, Hans; Huang, Hui-Ting; Lin, Hsi-Hui; Shen, Meng-Ru; Tang, Ming-Jer; Chiu, Wen-Tai

    2015-09-01

    Ca(2+) -mediated formation of cell polarity is essential for directional migration which plays an important role in physiological and pathological processes in organisms. To examine the critical role of store-operated Ca(2+) entry, which is the major form of extracellular Ca(2+) influx in non-excitable cells, in the formation of cell polarity, we employed human bone osteosarcoma U2OS cells, which exhibit distinct morphological polarity during directional migration. Our analyses showed that Ca(2+) was concentrated at the rear end of cells and that extracellular Ca(2+) influx was important for cell polarization. Inhibition of store-operated Ca(2+) entry using specific inhibitors disrupted the formation of cell polarity in a dose-dependent manner. Moreover, the channelosomal components caveolin-1, TRPC1, and Orai1 were concentrated at the rear end of polarized cells. Knockdown of TRPC1 or a TRPC inhibitor, but not knockdown of Orai1, reduced cell polarization. Furthermore, disruption of lipid rafts or overexpression of caveolin-1 contributed to the downregulation of cell polarity. On the other hand, we also found that cell polarity, store-operated Ca(2+) entry activity, and cell stiffness were markedly decreased by low substrate rigidity, which may be caused by the disorganization of actin filaments and microtubules that occurs while regulating the activity of the mechanosensitive TRPC1 channel.

  11. MBD3 inhibits formation of liver cancer stem cells

    PubMed Central

    Li, Ruizhi; He, Qihua; Han, Shuo; Zhang, Mingzhi; Liu, Jinwen; Su, Ming; Wei, Shiruo; Wang, Xuan; Shen, Li

    2017-01-01

    Liver cancer cells can be reprogrammed into induced cancer stem cells (iCSCs) by exogenous expression of the reprogramming transcription factors Oct4, Sox2, Klf4 and c-Myc (OSKM). The nucleosome remodeling and deacetylase (NuRD) complex is essential for reprogramming somatic cells. In this study, we investigated the function of NuRD in the induction of liver CSCs. We showed that suppression of methyl-CpG binding domain protein 3 (MBD3), a core subunit of the NuRD repressor complex, together with OSKM transduction, induces conversion of liver cancer cells into stem-like cells. Expression of the transcription factor c-JUN is increased in MBD3-depleted iCSCs, and c-JUN activates endogenous pluripotent genes and regulates iCSC-related genes. These results indicate that MBD3/NuRD inhibits the induction of iCSCs, while c-JUN facilitates the generation of CSC-like properties. The iCSC reprogramming approach devised here provides a novel platform for dissection of the disordered signaling in liver CSCs. In addition, our results indicate that c-JUN may serve as a potential target for liver cancer therapy. PMID:27894081

  12. Kinetics of Lipofuscin Formation in Aging Retinal Pigment Epithelium Cells

    NASA Astrophysics Data System (ADS)

    Family, Fereydoon; Mazzitello, K. I.; Arizmendi, C. M.; Grossniklaus, Hans E.

    2010-03-01

    Lipofuscin is a deposit that is formed over time by aggregation and clustering of incompletely degraded membrane material in various types of cells. Lipofuscin is made of free-radical-damaged protein and fat and is known to be present in age- related macular dgeneration (AMD), Alzheimer disease, and Parkinson disease. AMD is the leading cause of blindness in adults. The degradation of retinal pigment epithelium cells (RPE) through accumulation of lipsofuscin is considered a significant pathogenic factor in the development of AMD. We will present the results of a study of the kinetics of lipofuscin growth in RPE cells using Kinetic Monte Carlo simulations and scaling theory on a cluster aggregation model. The model captures the essential physics of lipofuscin growth in the cells. A remarkable feature is that small particles may be removed from the cells while the larger ones become fixed and grow by aggregation. We compare our results with the number of lipofuscin granules in eyes with early age-related degeneration.

  13. Biofilm formation on polystyrene in detached vs. planktonic cells of polyhydroxyalkanoate-accumulating Halomonas venusta.

    PubMed

    Berlanga, Mercedes; Domènech, Òscar; Guerrero, Ricardo

    2014-12-01

    Biofilm development is characterized by distinct stages of initial attachment, microcolony formation and maturation (sessile cells), and final detachment (dispersal of new, planktonic cells). In this work we examined the influence of polyhydroxyalkanoate (PHA) accumulation on bacterial surface properties and biofilm formation on polystyrene in detached vs. planktonic cells of an environmental strain isolated from microbial mats, Halomonas venusta MAT28. This strain was cultured either in an artificial biofilm in which the cells were immobilized on alginate beads (sessile) or as free-swimming (planktonic) cells. For the two modes of growth, conditions allowing or preventing PHA accumulation were established. Cells detached from alginate beads and their planktonic counterparts were used to study cell surface properties and cellular adhesion on polystyrene. Detached cells showed a slightly higher affinity than planktonic cells for chloroform (Lewis-acid) and a greater hydrophobicity (affinity for hexadecane and hexane). Those surface characteristics of the detached cells may explain their better adhesion on polystyrene compared to planktonic cells. Adhesion to polystyrene was not significantly different between H. venusta cells that had accumulated PHA vs. those that did not. These observations suggest that the surface properties of detached cells clearly differ from those of planktonic cells and that for at least the first 48 h after detachment from alginate beads H. venusta retained the capacity of sessile cells to adhere to polystyrene and to form a biofilm.

  14. Application of laser annealing to solar cell junction formation

    NASA Technical Reports Server (NTRS)

    Katzeff, J. S.; Lopez, M.; Josephs, R. H.

    1981-01-01

    The possibility of using high-energy Q-switched Nd:glass lasers to form pn junctions in solar cells by annealing ion-implanted substrates is investigated. The properties of laser annealed cells are analyzed by electrical, transmission electron microscopy, Rutherford backscattering and secondary ion mass spectrometry techniques. Tests indicate the laser annealed substrates to be damage-free and electrically active. Similar reference analysis of ion-implanted furnace-annealed substrates reveals the presence of residual defects in the form of dislocation lines and loops with substantial impurity redistribution evident for some anneal temperature/time regimes. Fabricated laser annealed cells exhibit excellent conversion efficiency. It is noted that additional improvements are anticipated once the anneal parameters for a back surface field are optimized.

  15. Formation and maintenance of the Golgi apparatus in plant cells.

    PubMed

    Ito, Yoko; Uemura, Tomohiro; Nakano, Akihiko

    2014-01-01

    The Golgi apparatus plays essential roles in intracellular trafficking, protein and lipid modification, and polysaccharide synthesis in eukaryotic cells. It is well known for its unique stacked structure, which is conserved among most eukaryotes. However, the mechanisms of biogenesis and maintenance of the structure, which are deeply related to ER-Golgi and intra-Golgi transport systems, have long been mysterious. Now having extremely powerful microscopic technologies developed for live-cell imaging, the plant Golgi apparatus provides an ideal system to resolve the question. The plant Golgi apparatus has unique features that are not conserved in other kingdoms, which will also give new insights into the Golgi functions in plant life. In this review, we will summarize the features of the plant Golgi apparatus and transport mechanisms around it, with a focus on recent advances in Golgi biogenesis by live imaging of plants cells.

  16. Investigation of Contact Formation during Silicon Solar Cell Production

    NASA Astrophysics Data System (ADS)

    Mojrová, Barbora

    2016-05-01

    This article deals with the investigation of the influence of sintering conditions on the formation process of screen printed contacts on passivated boron doped P+ emitters. The experiment was focused on measuring of resistance changes of two thick film pastes during firing processes with different conditions. Two different temperature profiles were compared at an atmospheric concentration of O2. The influence of the O2 concentration on resistance was investigated for one profile. A rapid thermal processing furnace modified for in-situ resistance measurements was used. The change of resistance was measured simultaneously with the temperature.

  17. Rap1 integrates tissue polarity, lumen formation, and tumorigenicpotential in human breast epithelial cells

    SciTech Connect

    Itoh, Masahiko; Nelson, Celeste M.; Myers, Connie A.; Bissell,Mina J.

    2006-09-29

    Maintenance of apico-basal polarity in normal breast epithelial acini requires a balance between cell proliferation, cell death, and proper cell-cell and cell-extracellular matrix signaling. Aberrations in any of these processes can disrupt tissue architecture and initiate tumor formation. Here we show that the small GTPase Rap1 is a crucial element in organizing acinar structure and inducing lumen formation. Rap1 activity in malignant HMT-3522 T4-2 cells is appreciably higher than in S1 cells, their non-malignant counterparts. Expression of dominant-negative Rap1 resulted in phenotypic reversion of T4-2 cells, led to formation of acinar structures with correct apico-basal polarity, and dramatically reduced tumor incidence despite the persistence of genomic abnormalities. The resulting acini contained prominent central lumina not observed when other reverting agents were used. Conversely, expression of dominant-active Rap1 in T4-2 cells inhibited phenotypic reversion and led to increased invasiveness and tumorigenicity. Thus, Rap1 acts as a central regulator of breast architecture, with normal levels of activation instructing apical polarity during acinar morphogenesis, and increased activation inducing tumor formation and progression to malignancy.

  18. A novel AhR ligand, 2AI, protects the retina from environmental stress

    PubMed Central

    Gutierrez, Mark A.; Davis, Sonnet S.; Rosko, Andrew; Nguyen, Steven M.; Mitchell, Kylie P.; Mateen, Samiha; Neves, Joana; Garcia, Thelma Y.; Mooney, Shaun; Perdew, Gary H.; Hubbard, Troy D.; Lamba, Deepak A.; Ramanathan, Arvind

    2016-01-01

    Various retinal degenerative diseases including dry and neovascular age-related macular degeneration (AMD), retinitis pigmentosa, and diabetic retinopathy are associated with the degeneration of the retinal pigmented epithelial (RPE) layer of the retina. This consequently results in the death of rod and cone photoreceptors that they support, structurally and functionally leading to legal or complete blindness. Therefore, developing therapeutic strategies to preserve cellular homeostasis in the RPE would be a favorable asset in the clinic. The aryl hydrocarbon receptor (AhR) is a conserved, environmental ligand-dependent, per ARNT-sim (PAS) domain containing bHLH transcription factor that mediates adaptive response to stress via its downstream transcriptional targets. Using in silico, in vitro and in vivo assays, we identified 2,2′-aminophenyl indole (2AI) as a potent synthetic ligand of AhR that protects RPE cells in vitro from lipid peroxidation cytotoxicity mediated by 4-hydroxynonenal (4HNE) as well as the retina in vivo from light-damage. Additionally, metabolic characterization of this molecule by LC-MS suggests that 2AI alters the lipid metabolism of RPE cells, enhancing the intracellular levels of palmitoleic acid. Finally, we show that, as a downstream effector of 2AI-mediated AhR activation, palmitoleic acid protects RPE cells from 4HNE-mediated stress, and light mediated retinal degeneration in mice. PMID:27364765

  19. Inhibition of macrophage-derived foam cell formation by ezetimibe via the caveolin-1/MAPK pathway.

    PubMed

    Qin, Li; Yang, Yun-Bo; Yang, Yi-Xin; Zhu, Neng; Liu, Zheng; Ni, Ya-Guang; Li, Shun-Xiang; Zheng, Xi-Long; Liao, Duan-Fang

    2016-02-01

    Ezetimibe, a selective inhibitor of intestinal cholesterol absorption, effectively reduces plasma cholesterol, but its effect on atherosclerosis is unclear. Foam cell formation has been implicated as a key mediator during the development of atherosclerosis. The purpose of this study was to investigate the effects of ezetimibe on foam cell formation and explore the underlying mechanism. The results presented here show that ezetimibe reduces atherosclerotic lesions in apolipoprotein E deficient (apoE-/-) mice by lowering cholesterol levels. Treatment of macrophages with Chol:MβCD resulted in foam cell formation, which was concentration-dependently inhibited by the presence of ezetimibe. Mechanically, ezetimibe treatment downregulated the expression of CD36 and scavenger receptor class B1 (SR-B1), but upregulated the expression of apoE and caveolin-1 in macrophage-derived foam cells, which kept consistent with our microarray results. Moreover, treatment with ezetimibe abrogated the increase of phospho-extracellular signal regulated kinase (ERK) 1/2 and their nuclear accumulation in foam cells. Inhibition of the MAPK pathway by the MEK inhibitor PD98059 attenuated the inhibitory effect of ezetimibe on the expression of p-ERK1/2 and caveolin-1. Taken together, these results showed that ezetimibe suppressed foam cell formation via the caveolin-1/MAPK signalling pathway, suggesting that inhibition of foam cell formation might be a novel mechanism underlying the anti-atherosclerotic effect of ezetimibe.

  20. High-Throughput Single-Cell Derived Sphere Formation for Cancer Stem-Like Cell Identification and Analysis

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Chih; Ingram, Patrick N.; Fouladdel, Shamileh; McDermott, Sean P.; Azizi, Ebrahim; Wicha, Max S.; Yoon, Euisik

    2016-06-01

    Considerable evidence suggests that many malignancies are driven by a cellular compartment that displays stem cell properties. Cancer stem-like cells (CSCs) can be identified by expression of cell surface markers or enzymatic activity, but these methods are limited by phenotypic heterogeneity and plasticity of CSCs. An alternative phenotypic methodology based on in-vitro sphere formation has been developed, but it is typically labor-intensive and low-throughput. In this work, we present a 1,024-microchamber microfluidic platform for single-cell derived sphere formation. Utilizing a hydrodynamic capturing scheme, more than 70% of the microchambers capture only one cell, allowing for monitoring of sphere formation from heterogeneous cancer cell populations for identification of CSCs. Single-cell derived spheres can be retrieved and dissociated for single-cell analysis using a custom 96-gene panel to probe heterogeneity within the clonal CSC spheres. This microfluidic platform provides reliable and high-throughput sphere formation for CSC identification and downstream clonal analysis.

  1. High-Throughput Single-Cell Derived Sphere Formation for Cancer Stem-Like Cell Identification and Analysis

    PubMed Central

    Chen, Yu-Chih; Ingram, Patrick N.; Fouladdel, Shamileh; McDermott, Sean P.; Azizi, Ebrahim; Wicha, Max S.; Yoon, Euisik

    2016-01-01

    Considerable evidence suggests that many malignancies are driven by a cellular compartment that displays stem cell properties. Cancer stem-like cells (CSCs) can be identified by expression of cell surface markers or enzymatic activity, but these methods are limited by phenotypic heterogeneity and plasticity of CSCs. An alternative phenotypic methodology based on in-vitro sphere formation has been developed, but it is typically labor-intensive and low-throughput. In this work, we present a 1,024-microchamber microfluidic platform for single-cell derived sphere formation. Utilizing a hydrodynamic capturing scheme, more than 70% of the microchambers capture only one cell, allowing for monitoring of sphere formation from heterogeneous cancer cell populations for identification of CSCs. Single-cell derived spheres can be retrieved and dissociated for single-cell analysis using a custom 96-gene panel to probe heterogeneity within the clonal CSC spheres. This microfluidic platform provides reliable and high-throughput sphere formation for CSC identification and downstream clonal analysis. PMID:27292795

  2. Quality measures and assurance for AI (Artificial Intelligence) software

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1988-01-01

    This report is concerned with the application of software quality and evaluation measures to AI software and, more broadly, with the question of quality assurance for AI software. Considered are not only the metrics that attempt to measure some aspect of software quality, but also the methodologies and techniques (such as systematic testing) that attempt to improve some dimension of quality, without necessarily quantifying the extent of the improvement. The report is divided into three parts Part 1 reviews existing software quality measures, i.e., those that have been developed for, and applied to, conventional software. Part 2 considers the characteristics of AI software, the applicability and potential utility of measures and techniques identified in the first part, and reviews those few methods developed specifically for AI software. Part 3 presents an assessment and recommendations for the further exploration of this important area.

  3. NASA space station automation: AI-based technology review

    NASA Technical Reports Server (NTRS)

    Firschein, O.; Georgeff, M. P.; Park, W.; Neumann, P.; Kautz, W. H.; Levitt, K. N.; Rom, R. J.; Poggio, A. A.

    1985-01-01

    Research and Development projects in automation for the Space Station are discussed. Artificial Intelligence (AI) based automation technologies are planned to enhance crew safety through reduced need for EVA, increase crew productivity through the reduction of routine operations, increase space station autonomy, and augment space station capability through the use of teleoperation and robotics. AI technology will also be developed for the servicing of satellites at the Space Station, system monitoring and diagnosis, space manufacturing, and the assembly of large space structures.

  4. Down-regulation of MUC1 in cancer cells inhibits cell migration by promoting E-cadherin/catenin complex formation

    SciTech Connect

    Yuan Zhenglong; Wong, Sandy; Borrelli, Alexander; Chung, Maureen A.

    2007-10-26

    MUC1, a tumor associated glycoprotein, is over-expressed in most cancers and can promote proliferation and metastasis. The objective of this research was to study the role of MUC1 in cancer metastasis and its potential mechanism. Pancreatic (PANC1) and breast (MCF-7) cancer cells with stable 'knockdown' of MUC1 expression were created using RNA interference. {beta}-Catenin and E-cadherin protein expression were upregulated in PANC1 and MCF-7 cells with decreased MUC1 expression. Downregulation of MUC1 expression also induced {beta}-catenin relocation from the nucleus to the cytoplasm, increased E-cadherin/{beta}-catenin complex formation and E-cadherin membrane localization in PANC1 cells. PANC1 cells with 'knockdown' MUC1 expression had decreased in vitro cell invasion. This study suggested that MUC1 may affect cancer cell migration by increasing E-cadherin/{beta}-catenin complex formation and restoring E-cadherin membrane localization.

  5. Down-regulation of MUC1 in cancer cells inhibits cell migration by promoting E-cadherin/catenin complex formation.

    PubMed

    Yuan, Zhenglong; Wong, Sandy; Borrelli, Alexander; Chung, Maureen A

    2007-10-26

    MUC1, a tumor associated glycoprotein, is over-expressed in most cancers and can promote proliferation and metastasis. The objective of this research was to study the role of MUC1 in cancer metastasis and its potential mechanism. Pancreatic (PANC1) and breast (MCF-7) cancer cells with stable 'knockdown' of MUC1 expression were created using RNA interference. beta-Catenin and E-cadherin protein expression were upregulated in PANC1 and MCF-7 cells with decreased MUC1 expression. Downregulation of MUC1 expression also induced beta-catenin relocation from the nucleus to the cytoplasm, increased E-cadherin/beta-catenin complex formation and E-cadherin membrane localization in PANC1 cells. PANC1 cells with 'knockdown' MUC1 expression had decreased in vitro cell invasion. This study suggested that MUC1 may affect cancer cell migration by increasing E-cadherin/beta-catenin complex formation and restoring E-cadherin membrane localization.

  6. Calibrating AIS images using the surface as a reference

    NASA Technical Reports Server (NTRS)

    Smith, M. O.; Roberts, D. A.; Shipman, H. M.; Adams, J. B.; Willis, S. C.; Gillespie, A. R.

    1987-01-01

    A method of evaluating the initial assumptions and uncertainties of the physical connection between Airborne Imaging Spectrometer (AIS) image data and laboratory/field spectrometer data was tested. The Tuscon AIS-2 image connects to lab reference spectra by an alignment to the image spectral endmembers through a system gain and offset for each band. Images were calibrated to reflectance so as to transform the image into a measure that is independent of the solar radiant flux. This transformation also makes the image spectra directly comparable to data from lab and field spectrometers. A method was tested for calibrating AIS images using the surface as a reference. The surface heterogeneity is defined by lab/field spectral measurements. It was found that the Tuscon AIS-2 image is consistent with each of the initial hypotheses: (1) that the AIS-2 instrument calibration is nearly linear; (2) the spectral variance is caused by sub-pixel mixtures of spectrally distinct materials and shade, and (3) that sub-pixel mixtures can be treated as linear mixtures of pure endmembers. It was also found that the image can be characterized by relatively few endmembers using the AIS-2 spectra.

  7. DISTRIBUTION OF RADIOACTIVITY IN AUTOLYZED CELL WALL OF BACILLUS CEREUS DURING SPHEROPLAST FORMATION1

    PubMed Central

    Kronish, Donald P.; Mohan, Raam R.; Schwartz, Benjamin S.

    1964-01-01

    Kronish, Donald P. (Warner-Lambert Research Institute, Morris Plains, N.J.), Raam R. Mohan, and Benjamin S. Schwartz. Distribution of radioactivity in autolyzed cell wall of Bacillus cereus during spheroplast formation. J. Bacteriol. 87:581–587. 1964.—Spheroplasts of Bacillus cereus strain T were produced from cells grown in the presence of uniformly labeled C14-glucose. At regular intervals during spheroplast formation, enzymatically degraded cell wall was isolated by a new procedure. Radioactivity of solubilized cell wall in cell-free material increased from 2.5 to 42% of the total incorporated label during spheroplast formation. The rate of cell-wall degradation as measured by increase in radioactivity was biphasic with relative slopes of 2.0 and 5.0. During autolytic depolymerization of B. cereus cell wall, two major components were solubilized at different rates. Chemical fractionation revealed these to be a peptide and a mucopeptide. The possibility of two enzymes being involved in spheroplast formation and cell-wall degradation is discussed. Images PMID:14127573

  8. Study of budding yeast colony formation and its characterizations by using circular granular cell

    NASA Astrophysics Data System (ADS)

    Aprianti, D.; Haryanto, F.; Purqon, A.; Khotimah, S. N.; Viridi, S.

    2016-03-01

    Budding yeast can exhibit colony formation in solid substrate. The colony of pathogenic budding yeast can colonize various surfaces of the human body and medical devices. Furthermore, it can form biofilm that resists drug effective therapy. The formation of the colony is affected by the interaction between cells and with its growth media. The cell budding pattern holds an important role in colony expansion. To study this colony growth, the molecular dynamic method was chosen to simulate the interaction between budding yeast cells. Every cell was modelled by circular granular cells, which can grow and produce buds. Cohesion force, contact force, and Stokes force govern this model to mimic the interaction between cells and with the growth substrate. Characterization was determined by the maximum (L max) and minimum (L min) distances between two cells within the colony and whether two lines that connect the two cells in the maximum and minimum distances intersect each other. Therefore, it can be recognized the colony shape in circular, oval, and irregular shapes. Simulation resulted that colony formation are mostly in oval shape with little branch. It also shows that greater cohesion strength obtains more compact colony formation.

  9. Formation of newly synthesized adeno-associated virus capsids in the cell nucleus.

    PubMed

    Bell, Peter; Vandenberghe, Luk H; Wilson, James M

    2014-06-01

    Adeno-associated virus (AAV) particles inside the nucleus of a HEK 293 cell are shown by electron microscopy. Cells have been triple-transfected for vector production and were analyzed for capsid formation three days later. Newly assembled particle are visible as seemingly unstructured conglomerates or crystal-like arrays.

  10. Bone Niches, Hematopoietic Stem Cells, and Vessel Formation

    PubMed Central

    Tamma, Roberto; Ribatti, Domenico

    2017-01-01

    Bone marrow (BM) is a source of hematopoietic stem cells (HSCs). HSCs are localized in both the endosteum, in the so-called endosteal niche, and close to thin-walled and fenestrated sinusoidal vessel in the center of BM, in the so-called vascular niche. HSCs give rise to all types of mature blood cells through a process finely controlled by numerous signals emerging from the bone marrow niches where HSCs reside. This review will focus on the description of the role of BM niches in the control of the fate of HSCs and will also highlight the role of the BM niches in the regulation of vasculogenesis and angiogenesis. Moreover, alterations of the signals in niche microenvironment are involved in many aspects of tumor progression and vascularization and further knowledge could provide the basis for the development of new therapeutic strategies. PMID:28098778

  11. Role of microRNA-21 in the formation of insulin-producing cells from pancreatic progenitor cells.

    PubMed

    Bai, Chunyu; Li, Xiangchen; Gao, Yuhua; Wang, Kunfu; Fan, Yanan; Zhang, Shuang; Ma, Yuehui; Guan, Weijun

    2016-02-01

    MicroRNAs (miRNAs) regulate insulin secretion, pancreas development, and beta cell differentiation. In this study, to screen for miRNAs and their targets that function during insulin-producing cells (IPCs) formation, we examined the messenger RNA and microRNA expression profiles of pancreatic progenitor cells (PPCs) and IPCs using microarray and deep sequencing approaches, respectively. Combining our data with that from previous reports, we found that miR-21 and its targets play an important role in the formation of IPCs. However, the function of miR-21 in the formation of IPCs from PPCs is poorly understood. Therefore, we over-expressed or inhibited miR-21 and expressed small interfering RNAs of miR-21 targets in PPCs to investigate their functions in IPCs formation. We found that miR-21 acts as a bidirectional switch in the formation of IPCs by regulating the expression of target and downstream genes (SOX6, RPBJ and HES1). Small interfering RNAs were used to knock down these genes in PPCs to investigate their effects on IPCs formation. Single expression of si-RBPJ, si-SOX6 and si-HES1 in PPCs showed that si-RBPJ was an inhibitor, and that si-SOX6 and si-HES1 were promoters of IPCs formation, although si-HES1 induced formation of IPCs at higher rates than si-SOX6. These results suggest that endogenous miRNAs involved in the formation of IPCs from PPCs should be considered in the development of an effective cell transplant therapy for diabetes.

  12. Lipid body formation during maturation of human mast cells.

    PubMed

    Dichlberger, Andrea; Schlager, Stefanie; Lappalainen, Jani; Käkelä, Reijo; Hattula, Katarina; Butcher, Sarah J; Schneider, Wolfgang J; Kovanen, Petri T

    2011-12-01

    Lipid droplets, also called lipid bodies (LB) in inflammatory cells, are important cytoplasmic organelles. However, little is known about the molecular characteristics and functions of LBs in human mast cells (MC). Here, we have analyzed the genesis and components of LBs during differentiation of human peripheral blood-derived CD34(+) progenitors into connective tissue-type MCs. In our serum-free culture system, the maturing MCs, derived from 18 different donors, invariably developed triacylglycerol (TG)-rich LBs. Not known heretofore, the MCs transcribe the genes for perilipins (PLIN)1-4, but not PLIN5, and PLIN2 and PLIN3 display different degrees of LB association. Upon MC activation and ensuing degranulation, the LBs were not cosecreted with the cytoplasmic secretory granules. Exogenous arachidonic acid (AA) enhanced LB genesis in Triacsin C-sensitive fashion, and it was found to be preferentially incorporated into the TGs of LBs. The large TG-associated pool of AA in LBs likely is a major precursor for eicosanoid production by MCs. In summary, we demonstrate that cultured human MCs derived from CD34(+) progenitors in peripheral blood provide a new tool to study regulatory mechanisms involving LB functions, with particular emphasis on AA metabolism, eicosanoid biosynthesis, and subsequent release of proinflammatory lipid mediators from these cells.

  13. Dscam-Mediated Cell Recognition Regulates Neural Circuit Formation

    PubMed Central

    Hattori, Daisuke; Millard, S. Sean; Wojtowicz, Woj M.; Zipursky, S. Lawrence

    2009-01-01

    The Dscam family of immunoglobulin cell surface proteins mediates recognition events between neurons that play an essential role in the establishment of neural circuits. The Drosophila Dscam1 locus encodes tens of thousands of cell surface proteins via alternative splicing. These isoforms exhibit exquisite isoform-specific binding in vitro that mediates homophilic repulsion in vivo. These properties provide the molecular basis for self-avoidance, an essential developmental mechanism that allows axonal and dendritic processes to uniformly cover their synaptic fields. In a mechanistically similar fashion, homophilic repulsion mediated by Drosophila Dscam2 prevents processes from the same class of cells from occupying overlapping synaptic fields through a process called tiling. Genetic studies in the mouse visual system support the view that vertebrate DSCAM also promotes both self-avoidance and tiling. By contrast, DSCAM and DSCAM-L promote layer-specific targeting in the chick visual system, presumably through promoting homophilic adhesion. The fly and mouse studies underscore the importance of homophilic repulsion in regulating neural circuit assembly, whereas the chick studies suggest that DSCA Mproteins may mediate a variety of different recognition events during wiring in a context-dependent fashion. PMID:18837673

  14. Oligomer Formation of Tau Protein Hyperphosphorylated in Cells*

    PubMed Central

    Tepper, Katharina; Biernat, Jacek; Kumar, Satish; Wegmann, Susanne; Timm, Thomas; Hübschmann, Sabrina; Redecke, Lars; Mandelkow, Eva-Maria; Müller, Daniel J.; Mandelkow, Eckhard

    2014-01-01

    Abnormal phosphorylation (“hyperphosphorylation”) and aggregation of Tau protein are hallmarks of Alzheimer disease and other tauopathies, but their causative connection is still a matter of debate. Tau with Alzheimer-like phosphorylation is also present in hibernating animals, mitosis, or during embryonic development, without leading to pathophysiology or neurodegeneration. Thus, the role of phosphorylation and the distinction between physiological and pathological phosphorylation needs to be further refined. So far, the systematic investigation of highly phosphorylated Tau was difficult because a reliable method of preparing reproducible quantities was not available. Here, we generated full-length Tau (2N4R) in Sf9 cells in a well defined phosphorylation state containing up to ∼20 phosphates as judged by mass spectrometry and Western blotting with phospho-specific antibodies. Despite the high concentration in living Sf9 cells (estimated ∼230 μm) and high phosphorylation, the protein was not aggregated. However, after purification, the highly phosphorylated protein readily formed oligomers, whereas fibrils were observed only rarely. Exposure of mature primary neuronal cultures to oligomeric phospho-Tau caused reduction of spine density on dendrites but did not change the overall cell viability. PMID:25339173

  15. Density of founder cells affects spatial pattern formation and cooperation in Bacillus subtilis biofilms.

    PubMed

    van Gestel, Jordi; Weissing, Franz J; Kuipers, Oscar P; Kovács, Akos T

    2014-10-01

    In nature, most bacteria live in surface-attached sedentary communities known as biofilms. Biofilms are often studied with respect to bacterial interactions. Many cells inhabiting biofilms are assumed to express 'cooperative traits', like the secretion of extracellular polysaccharides (EPS). These traits can enhance biofilm-related properties, such as stress resilience or colony expansion, while being costly to the cells that express them. In well-mixed populations cooperation is difficult to achieve, because non-cooperative individuals can reap the benefits of cooperation without having to pay the costs. The physical process of biofilm growth can, however, result in the spatial segregation of cooperative from non-cooperative individuals. This segregation can prevent non-cooperative cells from exploiting cooperative neighbors. Here we examine the interaction between spatial pattern formation and cooperation in Bacillus subtilis biofilms. We show, experimentally and by mathematical modeling, that the density of cells at the onset of biofilm growth affects pattern formation during biofilm growth. At low initial cell densities, co-cultured strains strongly segregate in space, whereas spatial segregation does not occur at high initial cell densities. As a consequence, EPS-producing cells have a competitive advantage over non-cooperative mutants when biofilms are initiated at a low density of founder cells, whereas EPS-deficient cells have an advantage at high cell densities. These results underline the importance of spatial pattern formation for competition among bacterial strains and the evolution of microbial cooperation.

  16. Oxygen-consuming chlor alkali cell configured to minimize peroxide formation

    DOEpatents

    Chlistunoff, Jerzy B.; Lipp, Ludwig; Gottesfeld, Shimshon

    2006-08-01

    Oxygen-consuming zero gap chlor-alkali cell was configured to minimize peroxide formation. The cell included an ion-exchange membrane that divided the cell into an anode chamber including an anode and a cathode chamber including an oxygen gas diffusion cathode. The cathode included a single-piece of electrically conducting graphitized carbon cloth. Catalyst and polytetrafluoroethylene were attached to only one side of the cloth. When the cathode was positioned against the cation exchange membrane with the catalyst side away from the membrane, electrolysis of sodium chloride to chlorine and caustic (sodium hydroxide) proceeded with minimal peroxide formation.

  17. Statistical analysis of clone formation in cultures of human stem cells.

    PubMed

    Bochkov, N P; Vinogradova, M S; Volkov, I K; Voronina, E S; Kuleshov, N P

    2011-08-01

    We performed a statistical analysis of clone formation from aneuploid cells (chromosomes 6, 8, 11, X) in cultures of bone marrow-derived human multipotent mesenchymal stromal cells by spontaneous level of aneuploidy at different terms of culturing (from 2 to 19 cell cycles). It was found that the duration of cell cycle increased from 65.6 h at passages 2-3 to 164.5 h at passage 12. The expected ratio of aneuploid cells was calculated using modeled 5, 10, 20 and 30% selective preference in reproduction. The size of samples for detecting 10, 25, and 50% increased level of aneuploidy was calculated. The presented principles for evaluation of aneuploid clone formation may be used to distinguish clones of any abnormal cells.

  18. Practical strategies for modulating foam cell formation and behavior

    PubMed Central

    Uitz, Elisabeth; Bahadori, Babak; McCarty, Mark F; Moghadasian, Mohammed H

    2014-01-01

    Although high density lipoprotein (HDL)-mediated reverse cholesterol transport is crucial to the prevention and reversal of atheroma, a recent meta-analysis makes evident that current pharmaceutical strategies for modulating HDL cholesterol levels lower cardiovascular risk only to the extent that they concurrently decrease low density lipoprotein (LDL) cholesterol. This corresponds well with findings of a recent Mendelian randomization analysis, in which genetic polymorphisms associated with HDL cholesterol but no other known cardiovascular risk factors failed to predict risk for myocardial infarction. Although it is still seems appropriate to search for therapies that could improve the efficiency with which HDL particles induce reverse cholesterol transport, targeting HDL cholesterol levels per se with current measures appears to be futile. It may therefore be more promising to promote reverse cholesterol transport with agents that directly target foam cells. Macrophage expression of the cholesterol transport proteins adenosine triphosphate binding cassette transporter A1, adenosine triphosphate binding cassette transporter G1, and scavenger receptor class B member 1 is transcriptionally up-regulated by activated liver X receptors (LXR), whereas nuclear factor (NF)-kappaB antagonizes their expression. Taurine, which inhibits atherogenesis in rodent studies, has just been discovered to act as a weak agonist for LXRalpha. Conversely, it may be possible to oppose NF-kappaB activation in macrophages with a range of measures. Induction of heme oxygenase-1, which can be attained with phase 2 inducer phytochemicals such as lipoic acid and green tea catechins, promotes reverse cholesterol transport in macrophages and inhibits atherogenesis in rodents, likely due to, in large part, NF-kappaB antagonism. Inhibition of macrophage nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity with the spirulina-derived bilirubin-mimetic phycocyanobilin may also oppose

  19. Practical strategies for modulating foam cell formation and behavior.

    PubMed

    Uitz, Elisabeth; Bahadori, Babak; McCarty, Mark F; Moghadasian, Mohammed H

    2014-10-16

    Although high density lipoprotein (HDL)-mediated reverse cholesterol transport is crucial to the prevention and reversal of atheroma, a recent meta-analysis makes evident that current pharmaceutical strategies for modulating HDL cholesterol levels lower cardiovascular risk only to the extent that they concurrently decrease low density lipoprotein (LDL) cholesterol. This corresponds well with findings of a recent Mendelian randomization analysis, in which genetic polymorphisms associated with HDL cholesterol but no other known cardiovascular risk factors failed to predict risk for myocardial infarction. Although it is still seems appropriate to search for therapies that could improve the efficiency with which HDL particles induce reverse cholesterol transport, targeting HDL cholesterol levels per se with current measures appears to be futile. It may therefore be more promising to promote reverse cholesterol transport with agents that directly target foam cells. Macrophage expression of the cholesterol transport proteins adenosine triphosphate binding cassette transporter A1, adenosine triphosphate binding cassette transporter G1, and scavenger receptor class B member 1 is transcriptionally up-regulated by activated liver X receptors (LXR), whereas nuclear factor (NF)-kappaB antagonizes their expression. Taurine, which inhibits atherogenesis in rodent studies, has just been discovered to act as a weak agonist for LXRalpha. Conversely, it may be possible to oppose NF-kappaB activation in macrophages with a range of measures. Induction of heme oxygenase-1, which can be attained with phase 2 inducer phytochemicals such as lipoic acid and green tea catechins, promotes reverse cholesterol transport in macrophages and inhibits atherogenesis in rodents, likely due to, in large part, NF-kappaB antagonism. Inhibition of macrophage nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity with the spirulina-derived bilirubin-mimetic phycocyanobilin may also oppose

  20. Characterization of the axon initial segment (AIS) of motor neurons and identification of a para-AIS and a juxtapara-AIS, organized by protein 4.1B

    PubMed Central

    2011-01-01

    Background The axon initial segment (AIS) plays a crucial role: it is the site where neurons initiate their electrical outputs. Its composition in terms of voltage-gated sodium (Nav) and voltage-gated potassium (Kv) channels, as well as its length and localization determine the neuron's spiking properties. Some neurons are able to modulate their AIS length or distance from the soma in order to adapt their excitability properties to their activity level. It is therefore crucial to characterize all these parameters and determine where the myelin sheath begins in order to assess a neuron's excitability properties and ability to display such plasticity mechanisms. If the myelin sheath starts immediately after the AIS, another question then arises as to how would the axon be organized at its first myelin attachment site; since AISs are different from nodes of Ranvier, would this particular axonal region resemble a hemi-node of Ranvier? Results We have characterized the AIS of mouse somatic motor neurons. In addition to constant determinants of excitability properties, we found heterogeneities, in terms of AIS localization and Nav composition. We also identified in all α motor neurons a hemi-node-type organization, with a contactin-associated protein (Caspr)+ paranode-type, as well as a Caspr2+ and Kv1+ juxtaparanode-type compartment, referred to as a para-AIS and a juxtapara (JXP)-AIS, adjacent to the AIS, where the myelin sheath begins. We found that Kv1 channels appear in the AIS, para-AIS and JXP-AIS concomitantly with myelination and are progressively excluded from the para-AIS. Their expression in the AIS and JXP-AIS is independent from transient axonal glycoprotein-1 (TAG-1)/Caspr2, in contrast to juxtaparanodes, and independent from PSD-93. Data from mice lacking the cytoskeletal linker protein 4.1B show that this protein is necessary to form the Caspr+ para-AIS barrier, ensuring the compartmentalization of Kv1 channels and the segregation of the AIS, para-AIS

  1. The role of Ca2+ influx in endocytic vacuole formation in pancreatic acinar cells

    PubMed Central

    Voronina, Svetlana; Collier, David; Chvanov, Michael; Middlehurst, Ben; Beckett, Alison J.; Prior, Ian A.; Criddle, David N.; Begg, Malcolm; Mikoshiba, Katsuhiko; Sutton, Robert; Tepikin, Alexei V.

    2014-01-01

    The inducers of acute pancreatitis trigger a prolonged increase in the cytosolic Ca2+ concentration ([Ca2+]c), which is responsible for the damage to and eventual death of pancreatic acinar cells. Vacuolization is an important indicator of pancreatic acinar cell damage. Furthermore, activation of trypsinogen occurs in the endocytic vacuoles; therefore the vacuoles can be considered as ‘initiating’ organelles in the development of the cell injury. In the present study, we investigated the relationship between the formation of endocytic vacuoles and Ca2+ influx developed in response to the inducers of acute pancreatitis [bile acid taurolithocholic acid 3-sulfate (TLC-S) and supramaximal concentration of cholecystokinin-8 (CCK)]. We found that the inhibitor of STIM (stromal interaction molecule)/Orai channels, GSK-7975A, effectively suppressed both the Ca2+ influx (stimulated by inducers of pancreatitis) and the formation of endocytic vacuoles. Cell death induced by TLC-S or CCK was also inhibited by GSK-7975A. We documented the formation of endocytic vacuoles in response to store-operated Ca2+ entry (SOCE) induced by thapsigargin [TG; inhibitor of sarcoplasmic/endoplasmic reticulum (ER) Ca2+ pumps] and observed strong inhibition of TG-induced vacuole formation by GSK-7975A. Finally, we found that structurally-unrelated inhibitors of calpain suppress formation of endocytic vacuoles, suggesting that this Ca2+-dependent protease is a mediator between Ca2+ elevation and endocytic vacuole formation. PMID:25370603

  2. Pericellular matrix formation alters the efficiency of intracellular uptake of oligonucleotides in osteosarcoma cells.

    PubMed

    Suzuki, Yoshitaka; Nishida, Yoshihiro; Naruse, Takahiro; Gemba, Takefumi; Ishiguro, Naoki

    2009-03-01

    One of the crucial roles of tumor extracellular matrix is to act as a barrier to drug delivery. In this study, we analyzed the relationship between the formation of tumor extracellular matrix and the efficiency of intracellular uptake of oligonucleotides in human osteosarcoma cell lines, HOS, and MG-63. Oligonucleotides used in this study were nuclear factor-kappa B (NF-kappaB) decoy, which might be a therapeutic tool for neoplasms. Pericellular matrix formation was examined by particle exclusion assay. Cellular uptake of fluorescein isothiocyanate-labeled NF-kappaB decoy was evaluated by fluorescent microscopy and flow cytometry. Effects of NF-kappaB decoy on cell viability and cell cycle arrest in MG-63 cells were determined by MTT assay and flow cytometry, respectively. MG-63 cells exhibited abundant pericellular matrix with time compared with HOS cells. Uptake of fluorescein isothiocyanate-labeled NF-kappaB decoy decreased in MG-63 cells with time but not in HOS cells in both monolayer and three-dimensional culture using matrigel. However, after enzymatic removal of pericellular matrix, the uptake markedly recovered in MG-63 cells. NF-kappaB decoy inhibited cell proliferation and induced G0/G1 cell cycle arrest in MG-63 cells. These results suggest that abundant pericellular matrix might disturb the uptake of NF-kappaB decoy, and modification of pericellular matrix composition would increase the efficacy of exogenous oligonucleotides treatment for neoplasms.

  3. QHREDGS Enhances Tube Formation, Metabolism and Survival of Endothelial Cells in Collagen-Chitosan Hydrogels

    PubMed Central

    Miklas, Jason W.; Dallabrida, Susan M.; Reis, Lewis A.; Ismail, Nesreen; Rupnick, Maria; Radisic, Milica

    2013-01-01

    Cell survival in complex, vascularized tissues, has been implicated as a major bottleneck in advancement of therapies based on cardiac tissue engineering. This limitation motivates the search for small, inexpensive molecules that would simultaneously be cardio-protective and vasculogenic. Here, we present peptide sequence QHREDGS, based upon the fibrinogen-like domain of angiopoietin-1, as a prime candidate molecule. We demonstrated previously that QHREDGS improved cardiomyocyte metabolism and mitigated serum starved apoptosis. In this paper we further demonstrate the potency of QHREDGS in its ability to enhance endothelial cell survival, metabolism and tube formation. When endothelial cells were exposed to the soluble form of QHREDGS, improvements in endothelial cell barrier functionality, nitric oxide production and cell metabolism (ATP levels) in serum starved conditions were found. The functionality of the peptide was then examined when conjugated to collagen-chitosan hydrogel, a potential carrier for in vivo application. The presence of the peptide in the hydrogel mitigated paclitaxel induced apoptosis of endothelial cells in a dose dependent manner. Furthermore, the peptide modified hydrogels stimulated tube-like structure formation of encapsulated endothelial cells. When integrin αvβ3 or α5β1were antibody blocked during cell encapsulation in peptide modified hydrogels, tube formation was abolished. Therefore, the dual protective nature of the novel peptide QHREDGS may position this peptide as an appealing augmentation for collagen-chitosan hydrogels that could be used for biomaterial delivered cell therapies in the settings of myocardial infarction. PMID:24013716

  4. Verification and Validation of AI Software

    DTIC Science & Technology

    1992-05-01

    Carnap atid Bar-H[illel [t I] showed that a formial anialoguie of Shannon ’s In formation mneasure 1(q) =- q, log2(qj,) provides a nlatLiral explication...Functional (Correctness of Programs." Proceedings of the Seventh ACN1 S.vinposium on Principles of Pro- gramnhing Languages, 1,980) IIt IR. ( Carnap

  5. The MP65 gene is required for cell wall integrity, adherence to epithelial cells and biofilm formation in Candida albicans

    PubMed Central

    2011-01-01

    Background The MP65 gene of Candida albicans (orf19.1779) encodes a putative β-glucanase mannoprotein of 65 kDa, which plays a main role in a host-fungus relationship, morphogenesis and pathogenicity. In this study, we performed an extensive analysis of a mp65Δ mutant to assess the role of this protein in cell wall integrity, adherence to epithelial cells and biofilm formation. Results The mp65Δ mutant showed a high sensitivity to a range of cell wall-perturbing and degrading agents, especially Congo red, which induced morphological changes such as swelling, clumping and formation of hyphae. The mp65Δ mutant showed an activation of two MAPKs (Mkc1p and Cek1p), a high level of expression of two stress-related genes (DDR48 and SOD5), and a modulated expression of β-glucan epitopes, but no gross changes in cell wall polysaccharide composition. Interestingly, the mp65Δ mutant displayed a marked reduction in adhesion to BEC and Caco-2 cells and severe defects in biofilm formation when compared to the wild type. All of the mentioned properties were totally or partially recovered in a revertant strain, demonstrating the specificity of gene deletion. Conclusions We demonstrate that the MP65 gene of Candida albicans plays a significant role in maintaining cell wall integrity, as well as in adherence to epithelia and biofilm formation, which are major virulence attributes of this fungus. PMID:21575184

  6. Electroporation-induced formation of individual calcium entry sites in the cell body and processes of adherent cells.

    PubMed Central

    Teruel, M N; Meyer, T

    1997-01-01

    Electroporation is a widely used method for introducing macromolecules into cells. We developed an electroporation device that requires only 1 microl of sample to load adherent cells in a 10-mm2 surface area while retaining greater than 90% cell survivability. To better understand this device, field-induced permeabilization of adherent rat basophilic leukemia and neocortical neuroblastoma cells was investigated by using fluorescent calcium and voltage indicators. Rectangular field pulses led to the formation of only a few calcium entry sites, preferentially in the hyperpolarized parts of the cell body and processes. Individual entry sites were formed at the same locations when field pulses were repeated. Before calcium entry, a partial breakdown of the membrane potential was observed in both polar regions. Based on our results, a model is proposed for the formation and closure of macromolecule entry sites in adherent cells. First, the rapid formation of a large number of small pores leads to a partial membrane potential breakdown in both polar regions of the cell. Second, over tens of milliseconds, a few entry sites for macromolecules are formed, preferentially in the hyperpolarized part of cell body and processes, at locations defined by the local membrane structure. These entry sites reseal on a time scale of 50 ms to several seconds, with residual small pores remaining open for several minutes. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 8 FIGURE 9 PMID:9336174

  7. The Pool of ADP and ATP Regulates Anaerobic Product Formation in Resting Cells of Lactococcus lactis

    PubMed Central

    Palmfeldt, Johan; Paese, Marco; Hahn-Hägerdal, Bärbel; van Niel, Ed W. J.

    2004-01-01

    Lactococcus lactis grows homofermentatively on glucose, while its growth on maltose under anaerobic conditions results in mixed acid product formation in which formate, acetate, and ethanol are formed in addition to lactate. Maltose was used as a carbon source to study mixed acid product formation as a function of the growth rate. In batch and nitrogen-limited chemostat cultures mixed acid product formation was shown to be linked to the growth rate, and homolactic fermentation occurred only in resting cells. Two of the four lactococcal strains investigated with maltose, L. lactis 65.1 and MG1363, showed more pronounced mixed acid product formation during growth than L. lactis ATCC 19435 or IL-1403. In resting cell experiments all four strains exhibited homolactic fermentation. In resting cells the intracellular concentrations of ADP, ATP, and fructose 1,6-bisphosphate were increased and the concentration of Pi was decreased compared with the concentrations in growing cells. Addition of an ionophore (monensin or valinomycin) to resting cultures of L. lactis 65.1 induced mixed acid product formation concomitant with decreases in the ADP, ATP, and fructose 1,6-bisphosphate concentrations. ADP and ATP were shown to inhibit glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, and alcohol dehydrogenase in vitro. Alcohol dehydrogenase was the most sensitive enzyme and was totally inhibited at an adenine nucleotide concentration of 16 mM, which is close to the sum of the intracellular concentrations of ADP and ATP of resting cells. This inhibition of alcohol dehydrogenase might be partially responsible for the homolactic behavior of resting cells. A hypothesis regarding the level of the ATP-ADP pool as a regulating mechanism for the glycolytic flux and product formation in L. lactis is discussed. PMID:15345435

  8. Interleukin 18 inhibits osteoclast formation via T cell production of granulocyte macrophage colony-stimulating factor.

    PubMed Central

    Horwood, N J; Udagawa, N; Elliott, J; Grail, D; Okamura, H; Kurimoto, M; Dunn, A R; Martin, T; Gillespie, M T

    1998-01-01

    IL-18 inhibits osteoclast (OCL) formation in vitro independent of IFN-gamma production, and this was abolished by the addition of neutralizing antibodies to GM-CSF. We now establish that IL-18 was unable to inhibit OCL formation in cocultures using GM-CSF-deficient mice (GM-CSF -/-). Reciprocal cocultures using either wild-type osteoblasts with GM-CSF -/- spleen cells or GM-CSF -/- osteoblasts with wild-type spleen cells were examined. Wild-type spleen cells were required to elicit a response to IL-18 indicating that cells of splenic origin were the IL-18 target. As T cells comprise a large proportion of the spleen cell population, the role of T cells in osteoclastogenesis was examined. Total T cells were removed and repleted in various combinations. Addition of wild-type T cells to a GM-CSF -/- coculture restored IL-18 inhibition of osteoclastogenesis. Major subsets of T cells, CD4+ and CD8+, were also individually depleted. Addition of either CD4+ or CD8+ wild-type T cells restored IL-18 action in a GM-CSF -/- background, while IL-18 was ineffective when either CD4+ or CD8+ GM-CSF -/- T cells were added to a wild-type coculture. These results highlight the involvement of T cells in IL-18-induced OCL inhibition and provide evidence for a new OCL inhibitory pathway whereby IL-18 inhibits OCL formation due to action upon T cells promoting the release of GM-CSF, which in turn acts upon OCL precursors. PMID:9449693

  9. Carbon Onions as Nanoscopic Pressure Cells for Diamond Formation

    NASA Astrophysics Data System (ADS)

    Banhart, Florian

    1997-03-01

    Concentric-shell carbon onions form under electron irradiation of different carbon precursors in an electron microscope. Carbon onions under irradiation at high temperature are in a state of high compression with a considerable decrease of the c-plane spacing towards the centre. Under prolonged irradiation at temperatures around 900 K the cores of the graphitic onions transform into diamond crystals (F. Banhart and P.M. Ajayan, Nature 382), 433 (1996). Hence, carbon onions can be thought of as nanoscopic pressure cells for the directly observable nucleation and growth of diamond from graphitic material. The diamond crystals grow under further irradiation until the whole graphitic particles have transformed to diamond. Apparently the conversion of the graphitic structure to diamond starts at high pressure and proceeds at decreasing, possibly even at zero pressure. The experiment is carried out in a transmission electron microscope which enables us to monitor this phase transformation in-situ on an atomic scale.

  10. The inhibition of macrophage foam cell formation by tetrahydroxystilbene glucoside is driven by suppressing vimentin cytoskeleton.

    PubMed

    Yao, Wenjuan; Huang, Lei; Sun, Qinju; Yang, Lifeng; Tang, Lian; Meng, Guoliang; Xu, Xiaole; Zhang, Wei

    2016-10-01

    Macrophage foam cell formation triggered by oxLDL is an important event that occurs during the development of atherosclerosis. 2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside (TSG) exhibits significant anti-atherosclerotic activity. Herein we used U937 cells induced by PMA and oxLDL in vitro to investigate the inhibitory effects of TSG on U937 differentiation and macrophage foam cell formation. TSG pretreatment markedly inhibited cell differentiation induced by PMA, macrophage apoptosis and foam cell formation induced by oxLDL. The inhibition of vimentin expression and cleavage was involved in these inhibitory effects of TSG. The suppression of vimentin by siRNA in U937 significantly inhibited cell differentiation, apoptosis and foam cell formation. Using inhibitors for TGFβR1 and PI3K, we found that vimentin production in U937 cells is regulated by TGFβ/Smad signaling, but not by PI3K-Akt-mTOR signaling. Meanwhile, TSG pretreatment inhibited both the expression of TGFβ1 and the phosphorylation of Smad2 and Smad3, and TSG suppressed the nuclear translocation of Smad4 induced by PMA and oxLDL. Furthermore, TSG attenuated the induced caspase-3 activation and adhesion molecules levels by PMA and oxLDL. PMA and oxLDL increased the co-localization of vimentin with ICAM-1, which was attenuated by pretreatment with TSG. These results suggest that TSG inhibits macrophage foam cell formation through suppressing vimentin expression and cleavage, adhesion molecules expression and vimentin-ICAM-1 co-localization. The interruption of TGFβ/Smad pathway and caspase-3 activation is responsible for the downregulation of TSG on vimentin expression and degradation, respectively.

  11. Enlarging cells initiating apomixis in Hieracium praealtum transition to an embryo sac program prior to entering mitosis.

    PubMed

    Okada, Takashi; Hu, Yingkao; Tucker, Matthew R; Taylor, Jennifer M; Johnson, Susan D; Spriggs, Andrew; Tsuchiya, Tohru; Oelkers, Karsten; Rodrigues, Julio C M; Koltunow, Anna M G

    2013-09-01

    Hieracium praealtum forms seeds asexually by apomixis. During ovule development, sexual reproduction initiates with megaspore mother cell entry into meiosis and formation of a tetrad of haploid megaspores. The sexual pathway ceases when a diploid aposporous initial (AI) cell differentiates, enlarges, and undergoes mitosis, forming an aposporous embryo sac that displaces sexual structures. Embryo and endosperm development in aposporous embryo sacs is fertilization independent. Transcriptional data relating to apomixis initiation in Hieracium spp. ovules is scarce and the functional identity of the AI cell relative to other ovule cell types is unclear. Enlarging AI cells with undivided nuclei, early aposporous embryo sacs containing two to four nuclei, and random groups of sporophytic ovule cells not undergoing these events were collected by laser capture microdissection. Isolated amplified messenger RNA samples were sequenced using the 454 pyrosequencing platform and comparatively analyzed to establish indicative roles of the captured cell types. Transcriptome and protein motif analyses showed that approximately one-half of the assembled contigs identified homologous sequences in Arabidopsis (Arabidopsis thaliana), of which the vast majority were expressed during early Arabidopsis ovule development. The sporophytic ovule cells were enriched in signaling functions. Gene expression indicative of meiosis was notably absent in enlarging AI cells, consistent with subsequent aposporous embryo sac formation without meiosis. The AI cell transcriptome was most similar to the early aposporous embryo sac transcriptome when comparing known functional annotations and both shared expressed genes involved in gametophyte development, suggesting that the enlarging AI cell is already transitioning to an embryo sac program prior to mitotic division.

  12. Formation of bipolar spindles with two centrosomes in tetraploid cells established from normal human fibroblasts.

    PubMed

    Ohshima, Susumu; Seyama, Atsushi

    2012-09-01

    Tetraploid cells with unstable chromosomes frequently arise as an early step in tumorigenesis and lead to the formation of aneuploid cells. The mechanisms responsible for the chromosome instability of polyploid cells are not fully understood, although the supernumerary centrosomes in polyploid cells have been considered the major cause of chromosomal instability. The aim of this study was to examine the integrity of mitotic spindles and centrosomes in proliferative polyploid cells established from normal human fibroblasts. TIG-1 human fibroblasts were treated with demecolcine (DC) for 4 days to induce polyploidy, and the change in DNA content was monitored. Localization of centrosomes and mitotic spindles in polyploid mitotic cells was examined by immunohistochemistry and laser scanning cytometry. TIG-1 cells treated with DC became almost completely tetraploid at 2 weeks after treatment and grew at the same rate as untreated diploid cells. Most mitotic cells with 8C DNA content had only two centrosomes with bipolar spindles in established tetraploid cells, although they had four or more centrosomes with multipolar spindles at 3 days after DC treatment. The frequency of aneuploid cells increased as established tetraploid cells were propagated. These results indicate that tetraploid cells that form bipolar spindles with two centrosomes in mitosis can proliferate as diploid cells. These cells may serve as a useful model for studying the chromosome instability of polyploid cells.

  13. Adolescent idiopathic scoliosis (AIS), environment, exposome and epigenetics: a molecular perspective of postnatal normal spinal growth and the etiopathogenesis of AIS with consideration of a network approach and possible implications for medical therapy

    PubMed Central

    2011-01-01

    Genetic factors are believed to play an important role in the etiology of adolescent idiopathic scoliosis (AIS). Discordant findings for monozygotic (MZ) twins with AIS show that environmental factors including different intrauterine environments are important in etiology, but what these environmental factors may be is unknown. Recent evidence for common chronic non-communicable diseases suggests epigenetic differences may underlie MZ twin discordance, and be the link between environmental factors and phenotypic differences. DNA methylation is one important epigenetic mechanism operating at the interface between genome and environment to regulate phenotypic plasticity with a complex regulation across the genome during the first decade of life. The word exposome refers to the totality of environmental exposures from conception onwards, comprising factors in external and internal environments. The word exposome is used here also in relation to physiologic and etiopathogenetic factors that affect normal spinal growth and may induce the deformity of AIS. In normal postnatal spinal growth we propose a new term and concept, physiologic growth-plate exposome for the normal processes particularly of the internal environments that may have epigenetic effects on growth plates of vertebrae. In AIS, we propose a new term and concept pathophysiologic scoliogenic exposome for the abnormal processes in molecular pathways particularly of the internal environment currently expressed as etiopathogenetic hypotheses; these are suggested to have deforming effects on the growth plates of vertebrae at cell, tissue, structure and/or organ levels that are considered to be epigenetic. New research is required for chromatin modifications including DNA methylation in AIS subjects and vertebral growth plates excised at surgery. In addition, consideration is needed for a possible network approach to etiopathogenesis by constructing AIS diseasomes. These approaches may lead through screening

  14. Compartmentalization of ER-Bound Chaperone Confines Protein Deposit Formation to the Aging Yeast Cell.

    PubMed

    Saarikangas, Juha; Caudron, Fabrice; Prasad, Rupali; Moreno, David F; Bolognesi, Alessio; Aldea, Martí; Barral, Yves

    2017-03-20

    In order to produce rejuvenated daughters, dividing budding yeast cells confine aging factors, including protein aggregates, to the aging mother cell. The asymmetric inheritance of these protein deposits is mediated by organelle and cytoskeletal attachment and by cell geometry. Yet it remains unclear how deposit formation is restricted to the aging lineage. Here, we show that selective membrane anchoring and the compartmentalization of the endoplasmic reticulum (ER) membrane confine protein deposit formation to aging cells during division. Supporting the idea that the age-dependent deposit forms through coalescence of smaller aggregates, two deposits rapidly merged when placed in the same cell by cell-cell fusion. The deposits localized to the ER membrane, primarily to the nuclear envelope (NE). Strikingly, weakening the diffusion barriers that separate the ER membrane into mother and bud compartments caused premature formation of deposits in the daughter cells. Detachment of the Hsp40 protein Ydj1 from the ER membrane elicited a similar phenotype, suggesting that the diffusion barriers and farnesylated Ydj1 functioned together to confine protein deposit formation to mother cells during division. Accordingly, fluorescence correlation spectroscopy measurements in dividing cells indicated that a slow-diffusing, possibly client-bound Ydj1 fraction was asymmetrically enriched in the mother compartment. This asymmetric distribution depended on Ydj1 farnesylation and intact diffusion barriers. Taking these findings together, we propose that ER-anchored Ydj1 binds deposit precursors and prevents them from spreading into daughter cells during division by subjecting them to the ER diffusion barriers. This ensures that the coalescence of precursors into a single deposit is restricted to the aging lineage.

  15. Inverse modeling of biomass smoke emissions using the TOMS AI

    NASA Astrophysics Data System (ADS)

    Zhang, S. Y.; Penner, J. E.; Torres, O.

    2003-12-01

    Results of inverse modeling of biomass smoke emissions using the TOMS AI and a three-dimensional transport model are presented. The IMPACT model with DAO meteorology data in 1997 are utilized to obtain aerosol spatial and temporal distributions. Two absorbing aerosol types are considered, including biomass smoke and mineral dust. First, a radiative transfer model is applied to generate the modeled AI. Then a Bayesian inverse technique is applied to optimize the difference between the modeled AI and the EP TOMS AI in the same period by regulating monthly a priori biomass smoke emissions, while the dust emissions are fixed. The modeled AI with a posteriori emissions generally is in better agreement with the EP TOMS AI. The annual global a posteriori source increases by about 13% for the year 1997 (6.31 Tg/yr BC) in the base scenario, with a larger adjustment of monthly regional emissions. Five sensitivity scenarios are carried out, including sensitivity to the a priori uncertainties, the height of the smoke layer, the cloud screening criteria of the daily EP TOMS AI, the adjustment of emissions in a lumped region outside of the major biomass burning regions, and the covariances between observations. Results suggest that a posteriori annual global emissions in the sensitivity scenarios are within 15% of that of the base scenario. However, the difference of annual a posteriori emissions between the sensitivity scenarios and the base scenario can be as large as 50% on regional scale. We are also applying the inverse model technique to the year 2000 to compare with biomass emissions deduced from an analysis based on burned areas.

  16. Pectinous cell wall thickenings formation - A common defense strategy of plants to cope with Pb.

    PubMed

    Krzesłowska, Magdalena; Rabęda, Irena; Basińska, Aneta; Lewandowski, Michał; Mellerowicz, Ewa J; Napieralska, Anna; Samardakiewicz, Sławomir; Woźny, Adam

    2016-07-01

    Lead, one of the most abundant and hazardous trace metals affecting living organisms, has been commonly detected in plant cell walls including some tolerant plants, mining ecotypes and hyperaccumulators. We have previously shown that in tip growing Funaria sp. protonemata cell wall is remodeled in response to lead by formation of thickenings rich in low-methylesterified pectins (pectin epitope JIM5 - JIM5-P) able to bind metal ions, which accumulate large amounts of Pb. Hence, it leads to the increase of cell wall capacity for Pb compartmentalization. Here we show that diverse plant species belonging to different phyla (Arabidopsis, hybrid aspen, star duckweed), form similar cell wall thickenings in response to Pb. These thickenings are formed in tip growing cells such as the root hairs, and in diffuse growing cells such as meristematic and root cap columella cells of root apices in hybrid aspen and Arabidopsis and in mesophyll cells in star duckweed fronds. Notably, all analyzed cell wall thickenings were abundant in JIM5-P and accumulated high amounts of Pb. In addition, the co-localization of JIM5-P and Pb commonly occurred in these cells. Hence, cell wall thickenings formed the extra compartment for Pb accumulation. In this way plant cells increased cell wall capacity for compartmentalization of this toxic metal, protecting protoplast from its toxicity. As cell wall thickenings occurred in diverse plant species and cell types differing in the type of growth we may conclude that pectinous cell wall thickenings formation is a widespread defense strategy of plants to cope with Pb. Moreover, detection of natural defense strategy, increasing plant cell walls capacity for metal accumulation, reveals a promising direction for enhancing plant efficiency in phytoremediation.

  17. 76 FR 44045 - Establishment of the SANE/SART AI/AN Initiative Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-22

    ... of Justice Programs Establishment of the SANE/SART AI/AN Initiative Committee AGENCY: Office for... (SART) American Indian/Alaskan Native (AI/AN) Initiative (``SANE/SART AI/AN Initiative Committee'' or... (FACA), as amended, 5 U.S.C., App. 2. The SANE/SART AI/AN Initiative Committee will provide the...

  18. Leukosialin (CD43)-major histocompatibility class I molecule interactions involved in spontaneous T cell conjugate formation

    PubMed Central

    1996-01-01

    Resting T cells spontaneously adhere in a selective manner to potent accessory cells, such as dendritic cells (DC) and lymphoblastoid B blasts (LCL). Here we demonstrate that leukosialin (CD43) and major histocompatibility complex class I molecules (MHC-I) might play a critical role in this process. T cell conjugate formation with monocyte- derived DC (md-DC) and LCL could be strongly inhibited by either preincubating T cells with Fab fragments of CD43 monoclonal antibody (mAb) 6F5 or by preincubating md-DC or LCL with MHC-I mAb W6/32. Intact CD43 mAb 6F5, in contrast to monovalent Fab fragments, enhanced T cell adhesiveness by transactivating CD2 binding to CD58 molecules. Interestingly, induction of this proadhesive signal via CD43 with intact 6F5 mAb was found to revert mAb W6/32-mediated inhibition of T cell conjugate formation. These observations indicated that CD43 cross- linkage mimics and monovalent mAb 6F5 inhibits interaction of T cell CD43 with a stimulatory ligand on opposing cells, presumably MHC-I. For the demonstration of direct physical interaction between CD43 on T cells and MHC-I-coated beads it was necessary, however, to ligate CD2 on T cells with a stimulatory pair of CD2 mAbs (VIT13 plus TS2/18). This suggests that CD2 ligation crosswise upregulates CD43 binding avidity for MHC-I and that both adhesion molecule pairs (CD43/MHC-I and CD2/CD58) act in concert to induce and mediate T cell conjugate formation with certain cell types. PMID:8920865

  19. A lineage of diploid platelet-forming cells precedes polyploid megakaryocyte formation in the mouse embryo.

    PubMed

    Potts, Kathryn S; Sargeant, Tobias J; Markham, John F; Shi, Wei; Biben, Christine; Josefsson, Emma C; Whitehead, Lachlan W; Rogers, Kelly L; Liakhovitskaia, Anna; Smyth, Gordon K; Kile, Benjamin T; Medvinsky, Alexander; Alexander, Warren S; Hilton, Douglas J; Taoudi, Samir

    2014-10-23

    In this study, we test the assumption that the hematopoietic progenitor/colony-forming cells of the embryonic yolk sac (YS), which are endowed with megakaryocytic potential, differentiate into the first platelet-forming cells in vivo. We demonstrate that from embryonic day (E) 8.5 all megakaryocyte (MK) colony-forming cells belong to the conventional hematopoietic progenitor cell (HPC) compartment. Although these cells are indeed capable of generating polyploid MKs, they are not the source of the first platelet-forming cells. We show that proplatelet formation first occurs in a unique and previously unrecognized lineage of diploid platelet-forming cells, which develop within the YS in parallel to HPCs but can be specified in the E8.5 Runx1-null embryo despite the absence of the progenitor cell lineage.

  20. mTOR Enhances Foam Cell Formation by Suppressing the Autophagy Pathway

    PubMed Central

    Li, Lingxia; Niu, Xiaolin; Dang, Xiaoyan; Li, Ping; Qu, Li; Bi, Xiaoju; Gao, Yanxia; Hu, Yanfen; Li, Manxiang; Qiao, Wanhai; Peng, Zhuo; Pan, Longfei

    2014-01-01

    Recently, autophagy has drawn more attention in cardiovascular disease as it has important roles in lipid metabolism. Mammalian target of rapamycin (mTOR) is a key regulator of autophagy; however, its effect on atherosclerosis and the underlying mechanism remains undefined. In this study, an obvious upregulation of mTOR and p-mTOR protein was observed in macrophage-derived foam cells. Blocking mTOR expression with specific small interference RNA (siRNA) dramatically suppressed foam cell formation, accompanied by a decrease of lipid deposition. Further mechanistic analysis indicated that suppressing mTOR expression significantly upregulated autophagic marker LC3 expression and downregulated autophagy substrate p62 levels, indicating that mTOR silencing triggered autophagosome formation. Moreover, blocking mTOR expression obviously accelerated neutral lipid delivery to lysosome and cholesterol efflux from foam cells, implying that mTOR could induce macrophage foam cell formation by suppressing autophagic pathway. Further, mTOR silencing significantly upregulated ULK1 expression, which was accounted for mTOR-induced foam cell formation via autophagic pathway as treatment with ULK1 siRNA dampened LC3-II levels and increased p62 expression, concomitant with lipid accumulation and decreased cholesterol efflux from foam cells. Together, our data provide an insight into how mTOR accelerates the pathological process of atherosclerosis. Accordingly, blocking mTOR levels may be a promising therapeutic agent against atherosclerotic complications. PMID:24512183

  1. An improved model for nucleation-limited ice formation in living cells during freezing.

    PubMed

    Yi, Jingru; Liang, Xin M; Zhao, Gang; He, Xiaoming

    2014-01-01

    Ice formation in living cells is a lethal event during freezing and its characterization is important to the development of optimal protocols for not only cryopreservation but also cryotherapy applications. Although the model for probability of ice formation (PIF) in cells developed by Toner et al. has been widely used to predict nucleation-limited intracellular ice formation (IIF), our data of freezing Hela cells suggest that this model could give misleading prediction of PIF when the maximum PIF in cells during freezing is less than 1 (PIF ranges from 0 to 1). We introduce a new model to overcome this problem by incorporating a critical cell volume to modify the Toner's original model. We further reveal that this critical cell volume is dependent on the mechanisms of ice nucleation in cells during freezing, i.e., surface-catalyzed nucleation (SCN) and volume-catalyzed nucleation (VCN). Taken together, the improved PIF model may be valuable for better understanding of the mechanisms of ice nucleation in cells during freezing and more accurate prediction of PIF for cryopreservation and cryotherapy applications.

  2. The adaptor molecule SAP plays essential roles during invariant NKT cell cytotoxicity and lytic synapse formation.

    PubMed

    Das, Rupali; Bassiri, Hamid; Guan, Peng; Wiener, Susan; Banerjee, Pinaki P; Zhong, Ming-Chao; Veillette, André; Orange, Jordan S; Nichols, Kim E

    2013-04-25

    The adaptor molecule signaling lymphocytic activation molecule-associated protein (SAP) plays critical roles during invariant natural killer T (iNKT) cell ontogeny. As a result, SAP-deficient humans and mice lack iNKT cells. The strict developmental requirement for SAP has made it difficult to discern its possible involvement in mature iNKT cell functions. By using temporal Cre recombinase-mediated gene deletion to ablate SAP expression after completion of iNKT cell development, we demonstrate that SAP is essential for T-cell receptor (TCR)-induced iNKT cell cytotoxicity against T-cell and B-cell leukemia targets in vitro and iNKT-cell-mediated control of T-cell leukemia growth in vivo. These findings are not restricted to the murine system: silencing RNA-mediated suppression of SAP expression in human iNKT cells also significantly impairs TCR-induced cytolysis. Mechanistic studies reveal that iNKT cell killing requires the tyrosine kinase Fyn, a known SAP-binding protein. Furthermore, SAP expression is required within iNKT cells to facilitate their interaction with T-cell targets and induce reorientation of the microtubule-organizing center to the immunologic synapse (IS). Collectively, these studies highlight a novel and essential role for SAP during iNKT cell cytotoxicity and formation of a functional IS.

  3. Tubulogenesis in a simple cell cord requires the formation of bi-apical cells through two discrete Par domains.

    PubMed

    Denker, Elsa; Bocina, Ivana; Jiang, Di

    2013-07-01

    Apico-basal polarization is a crucial step in the de novo formation of biological tubes. In Ciona notochord, tubulogenesis occurs in a single file of cells in the absence of cell proliferation. This configuration presents a unique challenge for the formation of a continuous lumen. Here, we show that this geometric configuration is associated with a novel polarization strategy: the generation of bipolar epithelial cells possessing two apical/luminal domains instead of one, as in the conventional epithelium. At the molecular level, cells establish two discrete Par3/Par6/aPKC patches, and form two sets of tight junctions, in opposite points of the cells. The key molecule controlling the formation of both domains is Par3. Changing the position of the cells within the organ fundamentally changes their polarity and the number of apical domains they develop. These results reveal a new mechanism for tubulogenesis from the simplest cell arrangement, which occurs in other developmental contexts, including vertebrate vascular anastomosis.

  4. Miniature fuel cell with monolithically fabricated Si electrodes - Alloy catalyst formation -

    NASA Astrophysics Data System (ADS)

    Ogura, Daiki; Suzuki, Takahiro; Katayama, Noboru; Dowaki, Kiyoshi; Hayase, Masanori

    2013-12-01

    A novel Pd-Pt catalyst formation process was proposed for reduction of Pt usage. In our miniature fuel cells, porous Pt was used as the catalyst, and the Pt usage was quite high. To reduce the Pt usage, we have attempted to deposit Pt on porous Pd by galvanic replacement, and relatively large output was demonstrated. In this study, in order to reduce more Pt usage and explore the alloy catalyst formation process, atomic layer deposition by UPD-SLRR (Under Potential Deposition - Surface Limited Redox Replacement) was applied to the Pd-Pt catalyst formation. The new process was verified at each process steps by EDS elemental analysis, and the expected spectra were obtained. Prototype cells were constructed by the new process, and cell output was raised to 420mW/cm2 by the Pd-Pt catalyst from 125mW/cm2 with Pd catalyst.

  5. Plant metabolism and cell wall formation in space (microgravity) and on Earth

    NASA Technical Reports Server (NTRS)

    Lewis, Norman G.

    1994-01-01

    Variations in cell wall chemistry provide vascular plants with the ability to withstand gravitational forces, as well as providing facile mechanisms for correctional responses to various gravitational stimuli, e.g., in reaction wood formation. A principal focus of our current research is to precisely and systematically dissect the essentially unknown mechanism(s) of vascular plant cell wall assembly, particularly with respect to formation of its phenolic constituents, i.e., lignins and suberins, and how gravity impacts upon these processes. Formation of these phenolic polymers is of particular interest, since it appears that elaboration of their biochemical pathways was essential for successful land adaptation. By extrapolation, we are also greatly intrigued as to how the microgravity environment impacts upon 'normal' cell wall assembly mechanisms/metabolism.

  6. Promotion of experimental thrombus formation by the procoagulant activity of breast cancer cells

    NASA Astrophysics Data System (ADS)

    Berny-Lang, M. A.; Aslan, J. E.; Tormoen, G. W.; Patel, I. A.; Bock, P. E.; Gruber, A.; McCarty, O. J. T.

    2011-02-01

    The routine observation of tumor emboli in the peripheral blood of patients with carcinomas raises questions about the clinical relevance of these circulating tumor cells. Thrombosis is a common clinical manifestation of cancer, and circulating tumor cells may play a pathogenetic role in this process. The presence of coagulation-associated molecules on cancer cells has been described, but the mechanisms by which circulating tumor cells augment or alter coagulation remains unclear. In this study we utilized suspensions of a metastatic adenocarcinoma cell line, MDA-MB-231, and a non-metastatic breast epithelial cell line, MCF-10A, as models of circulating tumor cells to determine the thromobogenic activity of these blood-foreign cells. In human plasma, both metastatic MDA-MB-231 cells and non-metastatic MCF-10A cells significantly enhanced clotting kinetics. The effect of MDA-MB-231 and MCF-10A cells on clotting times was cell number-dependent and inhibited by a neutralizing antibody to tissue factor (TF) as well as inhibitors of activated factor X and thrombin. Using fluorescence microscopy, we found that both MDA-MB-231 and MCF-10A cells supported the binding of fluorescently labeled thrombin. Furthermore, in a model of thrombus formation under pressure-driven flow, MDA-MB-231 and MCF-10A cells significantly decreased the time to occlusion. Our findings indicate that the presence of breast epithelial cells in blood can stimulate coagulation in a TF-dependent manner, suggesting that tumor cells that enter the circulation may promote the formation of occlusive thrombi under shear flow conditions.

  7. The rap GTPases regulate B cell morphology, immune-synapse formation, and signaling by particulate B cell receptor ligands.

    PubMed

    Lin, Kevin B L; Freeman, Spencer A; Zabetian, Saba; Brugger, Hayley; Weber, Michele; Lei, Victor; Dang-Lawson, May; Tse, Kathy W K; Santamaria, Rene; Batista, Facundo D; Gold, Michael R

    2008-01-01

    B lymphocytes spread and extend membrane processes when searching for antigens and form immune synapses upon contacting cells that display antigens on their surface. Although these dynamic morphological changes facilitate B cell activation, the signaling pathways underlying these processes are not fully understood. We found that activation of the Rap GTPases was essential for these changes in B cell morphology. Rap activation was important for B cell receptor (BCR)- and lymphocyte-function-associated antigen-1 (LFA-1)-induced spreading, for BCR-induced immune-synapse formation, and for particulate BCR ligands to induce localized F-actin assembly and membrane-process extension. Rap activation and F-actin assembly were also required for optimal BCR signaling in response to particulate antigens but not soluble antigens. Thus by controlling B cell morphology and cytoskeletal organization, Rap might play a key role in the activation of B cells by particulate and cell-associated antigens.

  8. Impaired respiration elicits SrrAB-dependent programmed cell lysis and biofilm formation in Staphylococcus aureus

    PubMed Central

    Mashruwala, Ameya A; van de Guchte, Adriana; Boyd, Jeffrey M

    2017-01-01

    Biofilms are communities of microorganisms attached to a surface or each other. Biofilm-associated cells are the etiologic agents of recurrent Staphylococcus aureus infections. Infected human tissues are hypoxic or anoxic. S. aureus increases biofilm formation in response to hypoxia, but how this occurs is unknown. In the current study we report that oxygen influences biofilm formation in its capacity as a terminal electron acceptor for cellular respiration. Genetic, physiological, or chemical inhibition of respiratory processes elicited increased biofilm formation. Impaired respiration led to increased cell lysis via divergent regulation of two processes: increased expression of the AtlA murein hydrolase and decreased expression of wall-teichoic acids. The AltA-dependent release of cytosolic DNA contributed to increased biofilm formation. Further, cell lysis and biofilm formation were governed by the SrrAB two-component regulatory system. Data presented support a model wherein SrrAB-dependent biofilm formation occurs in response to the accumulation of reduced menaquinone. DOI: http://dx.doi.org/10.7554/eLife.23845.001 PMID:28221135

  9. Role of JNK in network formation of human lung microvascular endothelial cells

    PubMed Central

    Medhora, Meetha; Dhanasekaran, Anuradha; Pratt, Phillip F.; Cook, Craig R.; Dunn, Laurel K.; Gruenloh, Stephanie K.; Jacobs, Elizabeth R.

    2010-01-01

    The signaling mechanisms in vasculogenesis and/or angiogenesis remain poorly understood, limiting the ability to regulate growth of new blood vessels in vitro and in vivo. Cultured human lung microvascular endothelial cells align into tubular networks in the three-dimensional matrix, Matrigel. Overexpression of MAPK phosphatase-1 (MKP-1), an enzyme that inactivates the ERK, JNK, and p38 pathways, inhibited network formation of these cells. Adenoviral-mediated overexpression of recombinant MKP-3 (a dual specificity phosphatase that specifically inactivates the ERK pathway) and dominant negative or constitutively active MEK did not attenuate network formation in Matrigel compared with negative controls. This result suggested that the ERK pathway may not be essential for tube assembly, a conclusion which was supported by the action of specific MEK inhibitor PD 184352, which also did not alter network formation. Inhibition of the JNK pathway using SP-600125 or L-stereoisomer (L-JNKI-1) blocked network formation, whereas the p38 MAPK blocker SB-203580 slightly enhanced it. Inhibition of JNK also attenuated the number of small vessel branches in the developing chick chorioallantoic membrane. Our results demonstrate a specific role for the JNK pathway in network formation of human lung endothelial cells in vitro while confirming that it is essential for the formation of new vessels in vivo. PMID:18263671

  10. Inhibition of neurosphere formation in neural stem/progenitor cells by acrylamide.

    PubMed

    Chen, Jong-Hang; Lee, Don-Ching; Chen, Mei-Shu; Ko, Ying-Chin; Chiu, Ing-Ming

    2015-01-01

    Previous studies showed that transplantation of cultured neural stem/progenitor cells (NSPCs) could improve functional recovery for various neurological diseases. This study aims to develop a stem cell-based model for predictive toxicology of development in the neurological system after acrylamide exposure. Treatment of mouse (KT98/F1B-GFP) and human (U-1240 MG/F1B-GFP) NSPCs with 0.5 mM acrylamide resulted in the inhibition of neurosphere formation (definition of self-renewal ability in NSPCs), but not inhibition of cell proliferation. Apoptosis and differentiation of KT98 (a precursor of KT98/F1B-GFP) and KT98/F1B-GFP are not observed in acrylamide-treated neurospheres. Analysis of secondary neurosphere formation and differentiation of neurons and glia illustrated that acrylamide-treated KT98 and KT98/F1B-GFP neurospheres retain the NSPC properties, such as self-renewal and differentiation capacity. Correlation of acrylamide-inhibited neurosphere formation with cell-cell adhesion was observed in mouse NSPCs by live cell image analysis and the presence of acrylamide. Protein expression levels of cell adhesion molecules [neural cell adhesion molecule (NCAM) and N-cadherin] and extracellular signal-regulated kinases (ERK) in acrylamide-treated KT98/F1B-GFP and U-1240 MG/F1B-GFP neurospheres demonstrated that NCAM decreased and phospho-ERK (pERK) increased, whereas expression of N-cadherin remained unchanged. Analysis of AKT (protein kinase B, PKB)/β-catenin pathway showed decrease in phospho-AKT (p-AKT) and cyclin D1 expression in acrylamide-treated neurospheres of KT98/F1B-GFP. Furthermore, PD98059, an ERK phosphorylation inhibitor, attenuated acrylamide-induced ERK phosphorylation, indicating that pERK contributed to the cell proliferation, but not in neurosphere formation in mouse NSPCs. Coimmunoprecipitation results of KT98/F1B-GFP cell lysates showed that the complex of NCAM and fibroblast growth factor receptor 1 (FGFR1) is present in the neurosphere, and the

  11. Application of AI techniques to blast furnace operations

    SciTech Connect

    Iida, Osamu; Ushijima, Yuichi; Sawada, Toshiro

    1995-10-01

    It was during the first stages of application of artificial intelligence (AI) to industrial fields, that the ironmaking division of Mizushima works at Kawasaki Steel recognized its potential. Since that time, the division has sought applications for these techniques to solve various problems. AI techniques applied to control the No. 3 blast furnace operations at the Mizushima works include: Blast furnace control by a diagnostic type of expert system that gives guidance to the actions required for blast furnace operation as well as control of furnace heat by automatically setting blast temperature; Hot stove combustion control by a combination of fuzzy inference and a physical model to insure good thermal efficiency of the stove; and blast furnace burden control using neural networks makes it possible to connect the pattern of gas flow distribution with the condition of the furnace. Experience of AI to control the blast furnace and other ironmaking operations has proved its capability for achieving automation and increased operating efficiency. The benefits are very high. For these reasons, the applications of AI techniques will be extended in the future and new techniques studied to further improve the power of AI.

  12. Discovering Knowledge from AIS Database for Application in VTS

    NASA Astrophysics Data System (ADS)

    Tsou, Ming-Cheng

    The widespread use of the Automatic Identification System (AIS) has had a significant impact on maritime technology. AIS enables the Vessel Traffic Service (VTS) not only to offer commonly known functions such as identification, tracking and monitoring of vessels, but also to provide rich real-time information that is useful for marine traffic investigation, statistical analysis and theoretical research. However, due to the rapid accumulation of AIS observation data, the VTS platform is often unable quickly and effectively to absorb and analyze it. Traditional observation and analysis methods are becoming less suitable for the modern AIS generation of VTS. In view of this, we applied the same data mining technique used for business intelligence discovery (in Customer Relation Management (CRM) business marketing) to the analysis of AIS observation data. This recasts the marine traffic problem as a business-marketing problem and integrates technologies such as Geographic Information Systems (GIS), database management systems, data warehousing and data mining to facilitate the discovery of hidden and valuable information in a huge amount of observation data. Consequently, this provides the marine traffic managers with a useful strategic planning resource.

  13. Mechanisms for Cellular NO Oxidation and Nitrite Formation in Lung Epithelial Cells

    PubMed Central

    Zhao, Xue-Jun; Wang, Ling; Shiva, Sruti; Tejero, Jesus; Wang, Jun; Frizzell, Sam; Gladwin, Mark T.

    2013-01-01

    Airway lining fluid contains relatively high concentrations of nitrite and arterial blood levels of nitrite are higher than venous levels, suggesting the lung epithelium may represent an important source of nitrite in vivo. To investigate whether lung epithelial cells possess the ability to convert NO to nitrite by oxidation, and the effect of oxygen reactions on nitrite formation, the NO donor DETA NONOate was incubated with or without A549 cells or primary human bronchial epithelial (HBE) cells for 24 hrs under normoxic (21% O2) and hypoxic (1% O2) conditions. Nitrite production was significantly increased under all conditions in the presence of A549 or HBE cells, suggesting that both A549 and HBE cells have the capacity to oxidize NO to nitrite even under low oxygen conditions. The addition of oxy-hemoglobin (oxy-Hb) to the A549 cell media decreased the production of nitrite, consistent with NO scavenging limiting nitrite formation. Heat-denatured A549 cells produced much lower nitrite and bitrate, suggesting an enzymatic activity is required. This NO oxidation activity was found to be highest in membrane bound proteins with molecular sizes < 100 kDa. In addition, 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one] (ODQ) and cyanide inhibited formation of nitrite in A549 cells. It has been shown that ceruloplasmin (Cp) possesses an NO oxidase and nitrite synthase activity in plasma based on NO oxidation to nitrosonium cation (NO+). We observed that Cp is expressed intracellularly in lung epithelial A549 cells and secreted into medium under basal conditions and during cytokine stimulation. However, an analysis of Cp expression level and activity measured via ρ-phenylenediamine oxidase activity assay revealed very low activity compared with plasma, suggesting that there is insufficient Cp to contribute to detectable NO oxidation to nitrite in A549 cells. Additionally, Cp levels were knocked down using siRNA by more than 75% in A549 cells, with no significant change in

  14. Positioning of polarity formation by extracellular signaling during asymmetric cell division.

    PubMed

    Seirin Lee, Sungrim

    2016-07-07

    Anterior-posterior (AP) polarity formation of cell membrane proteins plays a crucial role in determining cell asymmetry, which ultimately generates cell diversity. In Caenorhabditis elegans, a single fertilized egg cell (P0), its daughter cell (P1), and the germline precursors (P2 and P3 cells) form two exclusive domains of different PAR proteins on the membrane along the anterior-posterior axis. However, the phenomenon of polarity reversal has been observed in which the axis of asymmetric cell division of the P2 and P3 cells is formed in an opposite manner to that of the P0 and P1 cells. The extracellular signal MES-1/SRC-1 has been shown to induce polarity reversal, but the detailed mechanism remains elusive. Here, using a mathematical model, I explore the mechanism by which MES-1/SRC-1 signaling can induce polarity reversal and ultimately affect the process of polarity formation. I show that a positive correlation between SRC-1 and the on-rate of PAR-2 is the essential mechanism underlying polarity reversal, providing a mathematical basis for the orientation of cell polarity patterns.

  15. Estrogen Receptor α Regulates β-Cell Formation During Pancreas Development and Following Injury.

    PubMed

    Yuchi, Yixing; Cai, Ying; Legein, Bart; De Groef, Sofie; Leuckx, Gunter; Coppens, Violette; Van Overmeire, Eva; Staels, Willem; De Leu, Nico; Martens, Geert; Van Ginderachter, Jo A; Heimberg, Harry; Van de Casteele, Mark

    2015-09-01

    Identifying pathways for β-cell generation is essential for cell therapy in diabetes. We investigated the potential of 17β-estradiol (E2) and estrogen receptor (ER) signaling for stimulating β-cell generation during embryonic development and in the severely injured adult pancreas. E2 concentration, ER activity, and number of ERα transcripts were enhanced in the pancreas injured by partial duct ligation (PDL) along with nuclear localization of ERα in β-cells. PDL-induced proliferation of β-cells depended on aromatase activity. The activation of Neurogenin3 (Ngn3) gene expression and β-cell growth in PDL pancreas were impaired when ERα was turned off chemically or genetically (ERα(-/-)), whereas in situ delivery of E2 promoted β-cell formation. In the embryonic pancreas, β-cell replication, number of Ngn3(+) progenitor cells, and expression of key transcription factors of the endocrine lineage were decreased by ERα inactivation. The current study reveals that E2 and ERα signaling can drive β-cell replication and formation in mouse pancreas.

  16. Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds.

    PubMed

    Lobo, Anderson O; Antunes, Erica F; Palma, Mariana Bs; Pacheco-Soares, Cristina; Trava-Airoldi, Vladimir J; Corat, Evaldo J

    2010-03-12

    Monolayer formation of SaOS-2 (human osteoblast-like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non-toxicity and the flat spreading with monolayer formation of the SaOs-2 on VACNT scaffolds surface indicate that they can be used for biomedical applications.

  17. Clonal distribution of osteoprogenitor cells in cultured chick periostea: Functional relationship to bone formation

    SciTech Connect

    McCulloch, C.A.; Fair, C.A.; Tenenbaum, H.C.; Limeback, H.; Homareau, R. )

    1990-08-01

    Folded explants of periosteum from embryonic chick calvaria form bone-like tissue when grown in the presence of ascorbic acid, organic phosphate, and dexamethasone. All osteoblast-like cells in these cultures arise de novo by differentiation of osteoprogenitor cells present in the periosteum. To study the spatial and functional relationships between bone formation and osteoprogenitor cells, cultures were continuously labeled with (3H)thymidine for periods of 1-5 days. Radioautographs of serial 2-microns plastic sections stained for alkaline phosphatase (AP) showed maximal labeling of 30% of fibroblastic (AP-negative) cells by 3 days while osteogenic cells (AP-positive) exhibited over 95% labeling by 5 days. No differential shifts in labeling indices, grain count histograms of fibroblastic and osteogenic cells or numbers of AP-positive cells were observed, indicating no significant recruitment of cells from the fibroblastic to the osteogenic compartment. Despite the continuous presence of (3H)thymidine, less than 35% of both osteoblasts and osteocytes were labeled at 5 days, indicating that only one-third of the osteoprogenitor cells had cycled prior to differentiation. Spatial clustering of (3H)thymidine-labeled cells was measured by computer-assisted morphometry and application of the Poisson distribution to assess contagion. Cluster size and number of labeled cells per cluster did not vary between 1-3 days, but the number of clusters increased 20-fold between Day 1 and Day 3. Three-dimensional reconstruction from serial sections showed that clusters formed long, tubular arrays of osteogenic cells up to eight cells in length and located within 2-3 cell layers from the bone surface. Selective killing of S-phase cells with two pulse labels of high specific activity (3H)thymidine at 1 and 2 days of culture completely blocked bone formation.

  18. [Recruitment of osteogenic cells to bone formation sites during development and fracture repair - German Version].

    PubMed

    Böhm, A-M; Dirckx, N; Maes, C

    2016-04-01

    Recruitment of osteoblast lineage cells to their bone-forming locations is essential for skeletal development and fracture healing. In developing bones, osteoprogenitor cells invade the cartilage mold to establish the primary ossification center. Similarly, osteogenic cells infiltrate and populate the callus tissue that is formed following an injury. Proper bone development and successful fracture repair must, therefore, rely on controlled temporal and spatial navigation cues guiding the cells to the sites where new bone formation is needed. Some cellular mechanisms and molecular pathways involved have been elucidated.

  19. In vitro enhancement of extracellular matrix formation as natural bioscaffold for stem cell culture

    NASA Astrophysics Data System (ADS)

    Naroeni, Aroem; Shalihah, Qonitha; Meilany, Sofy

    2017-02-01

    Growing cells in plastic with liquid media for in vitro study is very common but far from physiological. The use of scaffold materials is more biocompatible. Extracellular matrix provides tissue integrity which acts as a native scaffold for cell attachment and interaction, as well as it serves as a reservoir for growth factors. For this reason, we have developed natural scaffold from mice fibroblast to form a natural scaffold for stem cell culture. Fibroblasts were cultured under crowded condition and lysed to form natural scaffold. The natural scaffold formation was observed using immunofluorescence which then will be used and tested for stem cell propagation and differentiation.

  20. Cbln1 downregulates the formation and function of inhibitory synapses in mouse cerebellar Purkinje cells.

    PubMed

    Ito-Ishida, Aya; Kakegawa, Wataru; Kohda, Kazuhisa; Miura, Eriko; Okabe, Shigeo; Yuzaki, Michisuke

    2014-04-01

    The formation of excitatory and inhibitory synapses must be tightly coordinated to establish functional neuronal circuitry during development. In the cerebellum, the formation of excitatory synapses between parallel fibers and Purkinje cells is strongly induced by Cbln1, which is released from parallel fibers and binds to the postsynaptic δ2 glutamate receptor (GluD2). However, Cbln1's role, if any, in inhibitory synapse formation has been unknown. Here, we show that Cbln1 downregulates the formation and function of inhibitory synapses between Purkinje cells and interneurons. Immunohistochemical analyses with an anti-vesicular GABA transporter antibody revealed an increased density of interneuron-Purkinje cell synapses in the cbln1-null cerebellum. Whole-cell patch-clamp recordings from Purkinje cells showed that both the amplitude and frequency of miniature inhibitory postsynaptic currents were increased in cbln1-null cerebellar slices. A 3-h incubation with recombinant Cbln1 reversed the increased amplitude of inhibitory currents in Purkinje cells in acutely prepared cbln1-null slices. Furthermore, an 8-day incubation with recombinant Cbln1 reversed the increased interneuron-Purkinje cell synapse density in cultured cbln1-null slices. In contrast, recombinant Cbln1 did not affect cerebellar slices from mice lacking both Cbln1 and GluD2. Finally, we found that tyrosine phosphorylation was upregulated in the cbln1-null cerebellum, and acute inhibition of Src-family kinases suppressed the increased inhibitory postsynaptic currents in cbln1-null Purkinje cells. These findings indicate that Cbln1-GluD2 signaling inhibits the number and function of inhibitory synapses, and shifts the excitatory-inhibitory balance towards excitation in Purkinje cells. Cbln1's effect on inhibitory synaptic transmission is probably mediated by a tyrosine kinase pathway.

  1. Formation of electrical coupling between embryonic Xenopus muscle cells in culture.

    PubMed Central

    Chow, I; Poo, M M

    1984-01-01

    Electrical coupling between embryonic Xenopus muscle cells in 1-5 day old cultures was studied after isolated cells were manipulated into contact for various periods. The coupling was examined by measuring the electrotonic spread of acetylcholine (ACh)-induced membrane depolarizations or of potential changes induced by intracellular current injection. In 1 day old culture, cells developed coupling rapidly after contact. Strong coupling was observed within 20 min after contact was made. The rate of coupling formation was age dependent. The percentage of cell pairs that established detectable coupling within 30 min of contact decreased from 66% in 1 day culture to 0% in 5 day culture. Older cells, when put into contact for prolonged periods, developed substantial coupling, suggesting that the age of the culture affects the rate of coupling formation rather than the final extent of coupling. Pre-treatment of older cells with colchicine, metabolic inhibitors, Ca2+ and Mg2+-free saline, or trypsin significantly increased the rate of coupling formation to a level close to that of younger cells. This suggests that the reduced rate of coupling was not due to a lack of membrane precursors for the intercellular channels, but was probably due to the appearance of extramembranous constraints for the channel assembly. PMID:6699773

  2. Mechanical vibration inhibits osteoclast formation by reducing DC-STAMP receptor expression in osteoclast precursor cells.

    PubMed

    Kulkarni, Rishikesh N; Voglewede, Philip A; Liu, Dawei

    2013-12-01

    It is well known that physical inactivity leads to loss of muscle mass, but it also causes bone loss. Mechanistically, osteoclastogenesis and bone resorption have recently been shown to be regulated by vibration. However, the underlying mechanism behind the inhibition of osteoclast formation is yet unknown. Therefore, we investigated whether mechanical vibration of osteoclast precursor cells affects osteoclast formation by the involvement of fusion-related molecules such as dendritic cell-specific transmembrane protein (DC-STAMP) and P2X7 receptor (P2X7R). RAW264.7 (a murine osteoclastic-like cell line) cells were treated with 20ng/ml receptor activator of NF-κB ligand (RANKL). For 3 consecutive days, the cells were subjected to 1h of mechanical vibration with 20μm displacement at a frequency of 4Hz and compared to the control cells that were treated under the same condition but without the vibration. After 5days of culture, osteoclast formation was determined. Gene expression of DC-STAMP and P2X7R by RAW264.7 cells was determined after 1h of mechanical vibration, while protein production of the DC-STAMP was determined after 6h of postincubation after vibration. As a result, mechanical vibration of RAW264.7 cells inhibited the formation of osteoclasts. Vibration down-regulated DC-STAMP gene expression by 1.6-fold in the presence of RANKL and by 1.4-fold in the absence of RANKL. Additionally, DC-STAMP protein production was also down-regulated by 1.4-fold in the presence of RANKL and by 1.2-fold in the absence of RANKL in RAW264.7 cells in response to mechanical vibration. However, vibration did not affect P2X7R gene expression. Mouse anti-DC-STAMP antibody inhibited osteoclast formation in the absence of vibration. Our results suggest that mechanical vibration of osteoclast precursor cells reduces DC-STAMP expression in osteoclast precursor cells leading to the inhibition of osteoclast formation.

  3. DC-SIGN-mediated infectious synapse formation enhances X4 HIV-1 transmission from dendritic cells to T cells.

    PubMed

    Arrighi, Jean-François; Pion, Marjorie; Garcia, Eduardo; Escola, Jean-Michel; van Kooyk, Yvette; Geijtenbeek, Teunis B; Piguet, Vincent

    2004-11-15

    Dendritic cells (DCs) are essential for the early events of human immunodeficiency virus (HIV) infection. Model systems of HIV sexual transmission have shown that DCs expressing the DC-specific C-type lectin DC-SIGN capture and internalize HIV at mucosal surfaces and efficiently transfer HIV to CD4+ T cells in lymph nodes, where viral replication occurs. Upon DC-T cell clustering, internalized HIV accumulates on the DC side at the contact zone (infectious synapse), between DCs and T cells, whereas HIV receptors and coreceptors are enriched on the T cell side. Viral concentration at the infectious synapse may explain, at least in part, why DC transmission of HIV to T cells is so efficient.Here, we have investigated the role of DC-SIGN on primary DCs in X4 HIV-1 capture and transmission using small interfering RNA-expressing lentiviral vectors to specifically knockdown DC-SIGN. We demonstrate that DC-SIGN- DCs internalize X4 HIV-1 as well as DC-SIGN+ DCs, although binding of virions is reduced. Strikingly, DC-SIGN knockdown in DCs selectively impairs infectious synapse formation between DCs and resting CD4+ T cells, but does not prevent the formation of DC-T cells conjugates. Our results demonstrate that DC-SIGN is required downstream from viral capture for the formation of the infectious synapse between DCs and T cells. These findings provide a novel explanation for the role of DC-SIGN in the transfer and enhancement of HIV infection from DCs to T cells, a crucial step for HIV transmission and pathogenesis.

  4. Dentin-like tissue formation and biomineralization by multicellular human pulp cell spheres in vitro

    PubMed Central

    2014-01-01

    Introduction Maintaining or regenerating a vital pulp is a preferable goal in current endodontic research. In this study, human dental pulp cell aggregates (spheres) were applied onto bovine and human root canal models to evaluate their potential use as pre-differentiated tissue units for dental pulp tissue regeneration. Methods Human dental pulp cells (DPC) were derived from wisdom teeth, cultivated into three-dimensional cell spheres and seeded onto bovine and into human root canals. Sphere formation, tissue-like and mineralization properties as well as growth behavior of cells on dentin structure were evaluated by light microscopy (LM), confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Results Spheres and outgrown cells showed tissue-like properties, the ability to merge with other cell spheres and extra cellular matrix formation; CLSM investigation revealed a dense network of actin and focal adhesion contacts (FAC) inside the spheres and a pronounced actin structure of cells outgrown from the spheres. A dentin-structure-orientated migration of the cells was shown by SEM investigation. Besides the direct extension of the cells into dentinal tubules, the coverage of the tubular walls with cell matrix was detected. Moreover, an emulation of dentin-like structures with tubuli-like and biomineral formation was detected by SEM- and EDX-investigation. Conclusions The results of the present study show tissue-like behavior, the replication of tubular structures and the mineralization of human dental pulp spheres when colonized on root dentin. The application of cells in form of pulp spheres on root dentin reveals their beneficial potential for dental tissue regeneration. PMID:24946771

  5. Gravity-induced buds formation from protonemata apical cells in the mosses

    NASA Astrophysics Data System (ADS)

    Kyyak, Natalia; Khorkavtsiv, Yaroslava

    The acceleration of moss protonemata development after the exit it to light from darkness is important gravidependent morphogenetic manifestation of the moss protonemata. The accelerated development of mosses shows in transformation of apical protonemata cells into the gametophores buds (Ripetskyj et al., 1999). In order to establish, that such reaction on gravitation is general property of gravisensity species, or its typical only for single moss species, experiments with the following moss species - Bryum intermedium (Ludw.) Brig., Bryum caespiticium Hedw., Bryum argenteum Hedw., Dicranodontium denudatum (Brid.) Britt. were carried out. All these species in response to influence of gravitation were capable to form rich bunches of gravitropical protonemata in darkness, that testified to their gravisensity. After the transference of Petri dishes with gravitropical protonemata from darkness on light was revealed, that in 3 of the investigated species the gametophores buds were absent. Only B. argenteum has reacted to action of gravitation by buds formation from apical cells of the gravitropical protonemata. With the purpose of strengthening of buds formation process, the experiments with action of exogenous kinetin (in concentration of 10 (-6) M) were carried out. Kinetin essentially stimulated apical buds formation of B. argenteum. The quantity of apical buds has increased almost in three times in comparison with the control. Besides, on separate stolons a few (3-4) buds from one apical cell were formed. Experimentally was established, that the gametophores buds formation in mosses is controlled by phytohormones (Bopp, 1985; Demkiv et al., 1991). In conditions of gravity influence its essentially accelerated. Probably, gravity essentially strengthened acropetal transport of phytohormones and formation of attractive center in the protonemata apical cell. Our investigations have allowed to make the conclusion, that gravi-dependent formation of the apical buds is

  6. Artificial intelligence (AI) based tactical guidance for fighter aircraft

    NASA Technical Reports Server (NTRS)

    Mcmanus, John W.; Goodrich, Kenneth H.

    1990-01-01

    A research program investigating the use of artificial intelligence (AI) techniques to aid in the development of a Tactical Decision Generator (TDG) for Within Visual Range air combat engagements is discussed. The application of AI programming and problem solving methods in the development and implementation of the Computerized Logic For Air-to-Air Warfare Simulations (CLAWS), a second generation TDG, is presented. The knowledge-based systems used by CLAWS to aid in the tactical decision-making process are outlined in detail, and the results of tests to evaluate the performance of CLAWS versus a baseline TDG developed in FORTRAN to run in real time in the Langley Differential Maneuvering Simulator, are presented. To date, these test results have shown significant performance gains with respect to the TDG baseline in one-versus-one air combat engagements, and the AI-based TDG software has proven to be much easier to modify and maintain than the baseline FORTRAN TDG programs.

  7. Toward detecting California shrubland canopy chemistry with AIS data

    NASA Technical Reports Server (NTRS)

    Price, Curtis V.; Westman, Walter E.

    1987-01-01

    Airborne Imaging Spectrometer (AIS)-2 data of coastal sage scrub vegetation were examined for fine spectral features that might be used to predict concentrations of certain canopy chemical constituents. A Fourier notch filter was applied to the AIS data and the TREE and ROCK mode spectra were ratioed to a flat field. Portions of the resulting spectra resemble spectra for plant cellulose and starch in that both show reduced reflectance at 2100 and 2270 nm. The latter are regions of absorption of energy by organic bonds found in starch and cellulose. Whether the relationship is sufficient to predict the concentration of these chemicals from AIS spectra will require testing of the predictive ability of these wavebands with large field sample sizes.

  8. The effect of hot-rolling on chill-cast AI-AI3Ni, chill-cast AI-AI2Cu, and Unidirectionally Solidified AI-AI3Ni Eutectic Alloys

    NASA Astrophysics Data System (ADS)

    Jardine, F. S. J.; Cantor, B.

    1986-11-01

    The effect of hot-rolling on the mechanical properties and microstructures of chill-cast Al-Al3Ni, chill-cast Al-Al2Cu, and unidirectionally solidified Al-Al3Ni eutectic alloys has been studied. The chill-cast eutectic alloys were produced by casting into preheated mild steel molds placed on copper chills. This system promoted growth along the length of the ingot and not radially from the mold wall. Cellular microstructures resulted with good alignment of Al3Ni fibers or Al2Cu lamellae within the cells and an interfiber/lamellar spacing of ~ 1 /urn. In contrast, the Al-Al3Ni eutectic alloy was also unidirectionally solidified at a growth rate of 3 x 10-1 m s-1 in a conventional horizontal crystal grower. This produced well-aligned Al3Ni fibers with an interfiber spacing of 1.2 ώm. Both the unidirectionally solidified and chill-cast Al-Al3Ni eutectic alloy can be hot-rolled at 773 K to reductions in area of greater than 95 pct. Deformation was achieved by Al3Ni fiber fracturing followed by separation of the broken fiber fragments in the rolling direction. Additionally, for the chill-cast eutectic the cellular microstructure disappeared and the Al3Ni fibers were homogeneously distributed throughout the matrix, after area reductions of 60 to 70 pct. In both cases, the eutectic microstructure was deformed with a constant volume fraction of Al3Ni/unit volume being maintained during rolling. The chill-cast Al-Al2Cu eutectic alloy can be hot-rolled at 773 K to an area reduction of ~50 pct, after the continuous brittle Al2Cu phase within the cells has been ‘broken up’ by coarsening at high temperature. The variations of room temperature tensile properties for the chill-cast and unidirectionally solidified eutectic alloys were measured as a function of reduction of thickness during hot-rolling and the results were compared with predicted strengths from discontinuous fiber reinforcement theory.

  9. Induction of monocyte differentiation and foam cell formation in vitro by 7-ketocholesterol.

    PubMed

    Hayden, John M; Brachova, Libuse; Higgins, Karen; Obermiller, Lewis; Sevanian, Alex; Khandrika, Srikrishna; Reaven, Peter D

    2002-01-01

    Oxidized LDL (OxLDL) is composed of many potentially proatherogenic molecules, including oxysterols. Of the oxysterols, 7-ketocholesterol (7-KC) is found in relatively large abundance in OxLDL, as well as in atherosclerotic plaque and foam cells in vivo. Although there is evidence that 7-KC activates endothelial cells, its effect on monocytes is unknown. We tested the hypothesis that 7-KC may induce monocyte differentiation and promote foam cell formation. THP-1 cells were used as a monocyte model system and were treated with 7-KC over a range of concentrations from 0.5 to 10 microg/ml. Changes in cell adhesion properties, cell morphology, and expression of antigens characteristic of differentiated macrophages were monitored over a 7-day period. 7-KC promoted cells to firmly adhere and display morphologic features of differentiated macrophages; this effect was time and dose dependent and was markedly more potent than cholesterol treatment (45% of cells became adherent after 7 days of treatment with 7-KC at 10 microg/ml vs. less then 5% for control cells, P < 0.01). Similar effects were obtained when LDL enriched with 7-KC or OxLDL were added to THP-1 cells. 7-KC-differentiated cells expressed CD11b, CD36, and CD68, phagocytized latex beads, and formed lipid-laden foam cells after exposure to acetylated LDL or OxLDL. In contrast to 7-KC, oxysterols with known cell regulatory effects such as 25-hydroxycholesterol, 7beta-hydroxycholesterol, and (22R)-hydroxycholesterol did not effectively promote THP-1 differentiation. In conclusion, these results demonstrate for the first time that 7-KC, a prominent oxysterol formed in OxLDL by peroxidation of cholesterol, may play an important role in promoting monocyte differentiation and foam cell formation. These studies also suggest that 7-KC induces monocyte differentiation through a sterol-mediated regulatory pathway that remains to be characterized.

  10. MUC16 provides immune protection by inhibiting synapse formation between NK and ovarian tumor cells

    PubMed Central

    2010-01-01

    Background Cancer cells utilize a variety of mechanisms to evade immune detection and attack. Effective immune detection largely relies on the formation of an immune synapse which requires close contact between immune cells and their targets. Here, we show that MUC16, a heavily glycosylated 3-5 million Da mucin expressed on the surface of ovarian tumor cells, inhibits the formation of immune synapses between NK cells and ovarian tumor targets. Our results indicate that MUC16-mediated inhibition of immune synapse formation is an effective mechanism employed by ovarian tumors to evade immune recognition. Results Expression of low levels of MUC16 strongly correlated with an increased number of conjugates and activating immune synapses between ovarian tumor cells and primary naïve NK cells. MUC16-knockdown ovarian tumor cells were more susceptible to lysis by primary NK cells than MUC16 expressing controls. This increased lysis was not due to differences in the expression levels of the ligands for the activating receptors DNAM-1 and NKG2D. The NK cell leukemia cell line (NKL), which does not express KIRs but are positive for DNAM-1 and NKG2D, also conjugated and lysed MUC16-knockdown cells more efficiently than MUC16 expressing controls. Tumor cells that survived the NKL challenge expressed higher levels of MUC16 indicating selective lysis of MUC16low targets. The higher csMUC16 levels on the NKL resistant tumor cells correlated with more protection from lysis as compared to target cells that were never exposed to the effectors. Conclusion MUC16, a carrier of the tumor marker CA125, has previously been shown to facilitate ovarian tumor metastasis and inhibits NK cell mediated lysis of tumor targets. Our data now demonstrates that MUC16 expressing ovarian cancer cells are protected from recognition by NK cells. The immune protection provided by MUC16 may lead to selective survival of ovarian cancer cells that are more efficient in metastasizing within the peritoneal

  11. Formation of gut-like structures in vitro from mouse embryonic stem cells.

    PubMed

    Torihashi, Shigeko

    2006-01-01

    Embryonic stem (ES) cells have the potential to differentiate into all cell types originating from the three germ layers; however, there are still few reports about the formation of functional organs from embryonic stem cells. Recently, we reported that by hanging drops of mouse ES cells, embryoid bodies (EBs) formed gut-like structures in vitro composed of three layers corresponding to the epithelium, lamina propria, and musculature. The morphological features and the process of formation are similar to gut and its organogenesis in vivo. Thus, this is a good model for development of the gut and a useful tool for analysis of the factors required for gut organogenesis. The protocol basically involves a method of hanging drops to make EBs, which are then plated on coated dishes for outgrowth. EBs develop to form gut-like structures when induced to spontaneously enter a program of differentiation in vitro without addition of any extrinsic factors.

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

    PubMed

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

    2015-11-07

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

  13. Chibby promotes ciliary vesicle formation and basal body docking during airway cell differentiation.

    PubMed

    Burke, Michael C; Li, Feng-Qian; Cyge, Benjamin; Arashiro, Takeshi; Brechbuhl, Heather M; Chen, Xingwang; Siller, Saul S; Weiss, Matthew A; O'Connell, Christopher B; Love, Damon; Westlake, Christopher J; Reynolds, Susan D; Kuriyama, Ryoko; Takemaru, Ken-Ichi

    2014-10-13

    Airway multiciliated epithelial cells play crucial roles in the mucosal defense system, but their differentiation process remains poorly understood. Mice lacking the basal body component Chibby (Cby) exhibit impaired mucociliary transport caused by defective ciliogenesis, resulting in chronic airway infection. In this paper, using primary cultures of mouse tracheal epithelial cells, we show that Cby facilitates basal body docking to the apical cell membrane through proper formation of ciliary vesicles at the distal appendage during the early stages of ciliogenesis. Cby is recruited to the distal appendages of centrioles via physical interaction with the distal appendage protein CEP164. Cby then associates with the membrane trafficking machinery component Rabin8, a guanine nucleotide exchange factor for the small guanosine triphosphatase Rab8, to promote recruitment of Rab8 and efficient assembly of ciliary vesicles. Thus, our study identifies Cby as a key regulator of ciliary vesicle formation and basal body docking during the differentiation of airway ciliated cells.

  14. Comparative study on DBPs formation profiles of intermediate organics from hydroxyl radicals oxidation of microbial cells.

    PubMed

    Ou, Tai-You; Wang, Gen-Shuh

    2016-05-01

    This study assessed the characteristics of disinfection byproducts (DBPs) formation from intermediate organics during UV/H2O2 treatment of activated sludge and algae cells under various reaction conditions. The DBPs including trihalomethanes (THMs), haloacetic acids (HAAs), haloketones (HKs) and haloacetonitriles (HANs) in UV/H2O2-treated and chlorinated water were measured. The results showed that both dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) increased during the initial stage of UV/H2O2 treatment due to the lysis of sludge and algae cells, which enhanced the formation of both C- and N-DBPs; however, both DOC and DON decreased after longer reaction times. During the UV/H2O2 treatments, THMs formation potential (THMFP) peaked earlier than did HAAs formation potential (HAAFP). This shows that the dissolved organics released from lysis of microbial cells in the early stages of oxidation favor the production of THMs over HAAs; however, HAAs precursors increased with the oxidation time. Chlorination with bromide increased the formation of THMs and HAAs but less HKs and HANs were produced. Comparisons of normalized DBP formation potential (DBPFP) of samples collected during UV/H2O2 treatments of four different types of organic matter showed that the highest DBPFP occurred in filtered treated wastewater effluent, followed by samples of activated sludge, filtered eutrophicated pond water, and samples of algae cells. With increasing oxidation time, the dominant DBP species shifted from THMs to HAAs in the samples of activated sludge and algae cells. The DBPFP tests also showed that more HAAs were formed in biologically treated wastewater effluent, while the eutrophicated source water produced more THMs.

  15. Progesterone supplementation after ovulation: effects on corpus luteum function and on fertility of dairy cows subjected to AI or ET.

    PubMed

    Monteiro, Pedro L J; Nascimento, Anibal B; Pontes, Guilherme C S; Fernandes, Gabriela O; Melo, Leonardo F; Wiltbank, Milo C; Sartori, Roberto

    2015-10-15

    Three experiments were done to evaluate the effects of progesterone (P4) supplementation starting during metestrus on formation of the CL and on fertility of lactating dairy cows subjected to fixed-time artificial insemination (FTAI) or embryo transfer (ET). In experiment 1, 42 Holstein cows were randomly allocated to untreated (Control) or to receive an intravaginal implant containing 1.9 g of P4 from Day 3 to 20 after FTAI (controlled internal drug release [CIDR]). Blood samples were collected on Days 3, 4, 7, 11, 14, 17, 20, and 21 after FTAI to evaluate the effect of CIDR supplementation on plasma concentration of P4 using radioimmunoassay. Ultrasound scans were performed at Days 4, 7, 11, 14, and 20 to evaluate CL volume. In experiment 2, the effect on CIDR supplementation on fertility was evaluated in 668 Holstein and crossbred dairy cows that were subjected to FTAI and allocated randomly to untreated (AI-Control) or to receive a CIDR from Day 3 to 17 (AI-CIDR) after FTAI. In experiment 3, 360 Holstein cows were treated with PGF and after heat detection (Day 0), they were allocated to untreated (ET-Control) or to receive a CIDR from Day 4 ± 1 to 8 ± 1 (ET-CIDR-4) or a CIDR from 4 ± 1 to 18 ± 1 (ET-CIDR-14). In vitro-produced embryos were transferred on Day 8 ± 1. Pregnancy diagnoses were performed by ultrasound. In experiment 1, there was interaction between treatment and day in relation to plasma P4 on Days 4 and 7 due to CIDR supplementation. Independent of treatment, pregnant cows had higher plasma P4 from Day 14 to 21 than nonpregnant cows (P ≤ 0.05). Supplementation with CIDR did not alter CL development. In experiment 2, there was no effect of supplementation of P4 on pregnancy per AI on Day 32 (32.0% vs. 31.8%, for AI-Control and AI-CIDR, respectively) or pregnancy loss (15.6% vs. 17.6%, for AI-Control and AI-CIDR, respectively). In experiment 3, P4 supplementation compromised pregnancy per ET (P/ET) on Day 32 in both supplemented groups (39

  16. Multiple endothelial cells constitute the tip of developing blood vessels and polarize to promote lumen formation.

    PubMed

    Pelton, John C; Wright, Catherine E; Leitges, Michael; Bautch, Victoria L

    2014-11-01

    Blood vessel polarization in the apical-basal axis is important for directed secretion of proteins and lumen formation; yet, when and how polarization occurs in the context of angiogenic sprouting is not well understood. Here, we describe a novel topology for endothelial cells at the tip of angiogenic sprouts in several mammalian vascular beds. Two cells that extend filopodia and have significant overlap in space and time were present at vessel tips, both in vitro and in vivo. The cell overlap is more extensive than predicted for tip cell switching, and it sets up a longitudinal cell-cell border that is a site of apical polarization and lumen formation, presumably via a cord-hollowing mechanism. The extent of cell overlap at the tip is reduced in mice lacking aPKCζ, and this is accompanied by reduced distal extension of both the apical border and patent lumens. Thus, at least two polarized cells occupy the distal tip of blood vessel sprouts, and topology, polarization and lumenization along the longitudinal border of these cells are influenced by aPKCζ.

  17. Multiple endothelial cells constitute the tip of developing blood vessels and polarize to promote lumen formation

    PubMed Central

    Pelton, John C.; Wright, Catherine E.; Leitges, Michael; Bautch, Victoria L.

    2014-01-01

    Blood vessel polarization in the apical-basal axis is important for directed secretion of proteins and lumen formation; yet, when and how polarization occurs in the context of angiogenic sprouting is not well understood. Here, we describe a novel topology for endothelial cells at the tip of angiogenic sprouts in several mammalian vascular beds. Two cells that extend filopodia and have significant overlap in space and time were present at vessel tips, both in vitro and in vivo. The cell overlap is more extensive than predicted for tip cell switching, and it sets up a longitudinal cell-cell border that is a site of apical polarization and lumen formation, presumably via a cord-hollowing mechanism. The extent of cell overlap at the tip is reduced in mice lacking aPKCζ, and this is accompanied by reduced distal extension of both the apical border and patent lumens. Thus, at least two polarized cells occupy the distal tip of blood vessel sprouts, and topology, polarization and lumenization along the longitudinal border of these cells are influenced by aPKCζ. PMID:25336741

  18. Sequential Salinomycin Treatment Results in Resistance Formation through Clonal Selection of Epithelial-Like Tumor Cells.

    PubMed

    Kopp, Florian; Hermawan, Adam; Oak, Prajakta Shirish; Ulaganathan, Vijay Kumar; Herrmann, Annika; Elnikhely, Nefertiti; Thakur, Chitra; Xiao, Zhiguang; Knyazev, Pjotr; Ataseven, Beyhan; Savai, Rajkumar; Wagner, Ernst; Roidl, Andreas

    2014-12-01

    Acquiring therapy resistance is one of the major obstacles in the treatment of patients with cancer. The discovery of the cancer stem cell (CSC)-specific drug salinomycin raised hope for improved treatment options by targeting therapy-refractory CSCs and mesenchymal cancer cells. However, the occurrence of an acquired salinomycin resistance in tumor cells remains elusive. To study the formation of salinomycin resistance, mesenchymal breast cancer cells were sequentially treated with salinomycin in an in vitro cell culture assay, and the resulting differences in gene expression and salinomycin susceptibility were analyzed. We demonstrated that long-term salinomycin treatment of mesenchymal cancer cells resulted in salinomycin-resistant cells with elevated levels of epithelial markers, such as E-cadherin and miR-200c, a decreased migratory capability, and a higher susceptibility to the classic chemotherapeutic drug doxorubicin. The formation of salinomycin resistance through the acquisition of epithelial traits was further validated by inducing mesenchymal-epithelial transition through an overexpression of miR-200c. The transition from a mesenchymal to a more epithelial-like phenotype of salinomycin-treated tumor cells was moreover confirmed in vivo, using syngeneic and, for the first time, transgenic mouse tumor models. These results suggest that the acquisition of salinomycin resistance through the clonal selection of epithelial-like cancer cells could become exploited for improved cancer therapies by antagonizing the tumor-progressive effects of epithelial-mesenchymal transition.

  19. Synthetic niches for differentiation of human embryonic stem cells bypassing embryoid body formation.

    PubMed

    Liu, Yarong; Fox, Victoria; Lei, Yuning; Hu, Biliang; Joo, Kye-Il; Wang, Pin

    2014-07-01

    The unique self-renewal and pluripotency features of human embryonic stem cells (hESCs) offer the potential for unlimited development of novel cell therapies. Currently, hESCs are cultured and differentiated using methods, such as monolayer culture and embryoid body (EB) formation. As such, achieving efficient differentiation into higher order structures remains a challenge, as well as maintaining cell viability during differentiation into homogeneous cell populations. Here, we describe the application of highly porous polymer scaffolds as synthetic stem cell niches. Bypassing the EB formation step, these scaffolds are capable of three-dimensional culture of undifferentiated hESCs and subsequent directed differentiation into three primary germ layers. H9 hESCs were successfully maintained and proliferated in biodegradable polymer scaffolds based on poly (lactic-co-glycolic acid) (PLGA). The results showed that cells within PLGA scaffolds retained characteristics of undifferentiated pluripotent stem cells. Moreover, the scaffolds allowed differentiation towards the lineage of interest by the addition of growth factors to the culture system. The in vivo transplantation study revealed that the scaffolds could provide a microenvironment that enabled hESCs to interact with their surroundings, thereby promoting cell differentiation. Therefore, this approach, which provides a unique culture/differentiation system for hESCs, will find its utility in various stem cell-based tissue-engineering applications.

  20. Situated, strategic, and AI-Enhanced technology introduction to healthcare.

    PubMed

    Bushko, Renata G

    2005-01-01

    We work hard on creating AI-wings for physicians to let them fly higher and faster in diagnosing patients--a task that physicians do not want to automate. What we do not work hard on is determining the ENVIRONMENT in which physicians' AI wings are supposed to function. It seems to be a job for social/business analysts that have their own separate kingdom. For the sake of all of us (potential patients!) social/business consultants and their methodologies should not be treated as a separate kingdom. The most urgent task is to achieve synergy between (1) AI/Fuzzy/Neural research, (2) Applied medical AI, (3) Social/Business research on medical institutions. We need this synergy in order to assure humanistic medical technology; technology flexible and sensitive enough to facilitate healthcare work while leaving space for human pride and creativity. In order to achieve humanistic technology, designers should consider the impact of technological breakthroughs on the organizations in which this technology will function and the nature of work of humans destined to use this technology. Situated (different for each organization), Strategic (based on an in-depth knowledge of Healthcare business), and AI-Enhanced (ended with a dynamic model) method for introducing technology to Healthcare allows identifying areas where technology can make medical work easier. Using this method before automating human work will get us closer to the ideal where there is no discontinuity between design and use of programs; where the technology matches users' needs perfectly--the world with humanistic technology and healthcare workers with AI-wings.

  1. Survivin Modulates Squamous Cell Carcinoma-Derived Stem-Like Cell Proliferation, Viability and Tumor Formation in Vivo.

    PubMed

    Lotti, Roberta; Palazzo, Elisabetta; Petrachi, Tiziana; Dallaglio, Katiuscia; Saltari, Annalisa; Truzzi, Francesca; Quadri, Marika; Puviani, Mario; Maiorana, Antonino; Marconi, Alessandra; Pincelli, Carlo

    2016-01-12

    Squamous Cell Carcinoma-derived Stem-like Cells (SCC-SC) originate from alterations in keratinocyte stem cells (KSC) gene expression and sustain tumor development, invasion and recurrence. Since survivin, a KSC marker, is highly expressed in SCC-SC, we evaluate its role in SCC-SC cell growth and SCC models. Survivin silencing by siRNA decreases clonal growth of SCC keratinocytes and viability of total, rapidly adhering (RAD) and non-RAD (NRAD) cells from primary SCC. Similarly, survivin silencing reduces the expression of stem cell markers (OCT4, NOTCH1, CD133, β₁-integrin), while it increases the level of differentiation markers (K10, involucrin). Moreover, survivin silencing improves the malignant phenotype of SCC 3D-reconstruct, as demonstrated by reduced epidermal thickness, lower Ki-67 positive cell number, and decreased expression of MMP9 and psoriasin. Furthermore, survivin depletion by siRNA in Ras(G12V)-IκBα-derived tumors leads to smaller tumor formation characterized by lower mitotic index and reduced expression of the tumor-associated marker HIF1α, VEGF and CD51. Therefore, our results indicate survivin as a key gene in regulating SCC cancer stem cell formation and cSCC development.

  2. ROCK is involved in vasculogenic mimicry formation in hepatocellular carcinoma cell line.

    PubMed

    Zhang, Ji-Gang; Li, Xiao-Yu; Wang, Yu-Zhu; Zhang, Qi-Di; Gu, Sheng-Ying; Wu, Xin; Zhu, Guan-Hua; Li, Qin; Liu, Gao-Lin

    2014-01-01

    Ras homolog family member A (RhoA) and Rho-associated coiled coil-containing protein kinases 1 and 2 (ROCK1 and 2) are key regulators of focal adhesion, actomyosin contraction and cell motility. RhoA/ROCK signaling has emerged as an attractive target for the development of new cancer therapeutics. Whether RhoA/ROCK is involved in regulating the formation of tumor cell vasculogenic mimicry (VM) is largely unknown. To confirm this hypothesis, we performed in vitro experiments using hepatocellular carcinoma (HCC) cell lines. Firstly, we demonstrated that HCC cells with higher active RhoA/ROCK expression were prone to form VM channels, as compared with RhoA/ROCK low-expressing cells. Furthermore, Y27632 (a specific inhibitor of ROCK) rather than exoenzyme C3 (a specific inhibitor of RhoA) effectively inhibited the formation of tubular network structures in a dose-dependent manner. To elucidate the possible mechanism of ROCK on VM formation, real-time qPCR, western blot and immunofluorescence were used to detect changes of the key VM-related factors, including VE-cadherin, erythropoietin-producing hepatocellular carcinoma-A2 (EphA2), phosphoinositide 3-kinase (PI3K), matrix metalloproteinase (MMP)14, MMP2, MMP9 and laminin 5γ2-chain (LAMC2), and epithelial-mesenchymal-transition (EMT) markers: E-cadherin and Vimentin. The results showed that all the expression profiles were attenuated by blockage of ROCK. In addition, in vitro cell migration and invasion assays showed that Y27632 inhibited the migration and invasion capacity of HCC cell lines in a dose-dependent manner markedly. These data indicate that ROCK is an important mediator in the formation of tumor cell VM, and suggest that ROCK inhibition may prove useful in the treatment of VM in HCC.

  3. The Differential Formation of the LINC-Mediated Perinuclear Actin Cap in Pluripotent and Somatic Cells

    PubMed Central

    Khatau, Shyam B.; Kusuma, Sravanti; Hanjaya-Putra, Donny; Mali, Prashant; Cheng, Linzhao; Lee, Jerry S. H.; Gerecht, Sharon; Wirtz, Denis

    2012-01-01

    The actin filament cytoskeleton mediates cell motility and adhesion in somatic cells. However, whether the function and organization of the actin network are fundamentally different in pluripotent stem cells is unknown. Here we show that while conventional actin stress fibers at the basal surface of cells are present before and after onset of differentiation of mouse (mESCs) and human embryonic stem cells (hESCs), actin stress fibers of the actin cap, which wrap around the nucleus, are completely absent from undifferentiated mESCs and hESCs and their formation strongly correlates with differentiation. Similarly, the perinuclear actin cap is absent from human induced pluripotent stem cells (hiPSCs), while it is organized in the parental lung fibroblasts from which these hiPSCs are derived and in a wide range of human somatic cells, including lung, embryonic, and foreskin fibroblasts and endothelial cells. During differentiation, the formation of the actin cap follows the expression and proper localization of nuclear lamin A/C and associated linkers of nucleus and cytoskeleton (LINC) complexes at the nuclear envelope, which physically couple the actin cap to the apical surface of the nucleus. The differentiation of hESCs is accompanied by the progressive formation of a perinuclear actin cap while induced pluripotency is accompanied by the specific elimination of the actin cap, and that, through lamin A/C and LINC complexes, this actin cap is involved in progressively shaping the nucleus of hESCs undergoing differentiation. While, the localization of lamin A/C at the nuclear envelope is required for perinuclear actin cap formation, it is not sufficient to control nuclear shape. PMID:22574215

  4. Teratoma formation of human embryonic stem cells in three-dimensional perfusion culture bioreactors.

    PubMed

    Stachelscheid, H; Wulf-Goldenberg, A; Eckert, K; Jensen, J; Edsbagge, J; Björquist, P; Rivero, M; Strehl, R; Jozefczuk, J; Prigione, A; Adjaye, J; Urbaniak, T; Bussmann, P; Zeilinger, K; Gerlach, J C

    2013-09-01

    Teratoma formation in mice is today the most stringent test for pluripotency that is available for human pluripotent cells, as chimera formation and tetraploid complementation cannot be performed with human cells. The teratoma assay could also be applied for assessing the safety of human pluripotent cell-derived cell populations intended for therapeutic applications. In our study we examined the spontaneous differentiation behaviour of human embryonic stem cells (hESCs) in a perfused 3D multi-compartment bioreactor system and compared it with differentiation of hESCs and human induced pluripotent cells (hiPSCs) cultured in vitro as embryoid bodies and in vivo in an experimental mouse model of teratoma formation. Results from biochemical, histological/immunohistological and ultrastuctural analyses revealed that hESCs cultured in bioreactors formed tissue-like structures containing derivatives of all three germ layers. Comparison with embryoid bodies and the teratomas revealed a high degree of similarity of the tissues formed in the bioreactor to these in the teratomas at the histological as well as transcriptional level, as detected by comparative whole-genome RNA expression profiling. The 3D culture system represents a novel in vitro model that permits stable long-term cultivation, spontaneous multi-lineage differentiation and tissue formation of pluripotent cells that is comparable to in vivo differentiation. Such a model is of interest, e.g. for the development of novel cell differentiation strategies. In addition, the 3D in vitro model could be used for teratoma studies and pluripotency assays in a fully defined, controlled environment, alternatively to in vivo mouse models.

  5. Frame synchronization of satellite based on AIS signals

    NASA Astrophysics Data System (ADS)

    Ma, Shexiang; Zhao, Dawei

    2016-10-01

    Frame synchronization play a very important role in coding of AIS. There are much arithmetic like maximum-likelihood, correlation and so on. But most of those cannot achieve good performance with large frequency offset. As satellite-based AIS system exist larger time delay and Doppler frequency offset, this paper propose arithmetic of frame synchronization. It is based on folding auto-correlation, where the top half and second half of training sequence have largest correlation after it is modulated by GMSK. Simulation experiments indicate that this arithmetic has good anti-frequency-offset performance.

  6. Rapid prototyping and AI programming environments applied to payload modeling

    NASA Technical Reports Server (NTRS)

    Carnahan, Richard S., Jr.; Mendler, Andrew P.

    1987-01-01

    This effort focused on using artificial intelligence (AI) programming environments and rapid prototyping to aid in both space flight manned and unmanned payload simulation and training. Significant problems addressed are the large amount of development time required to design and implement just one of these payload simulations and the relative inflexibility of the resulting model to accepting future modification. Results of this effort have suggested that both rapid prototyping and AI programming environments can significantly reduce development time and cost when applied to the domain of payload modeling for crew training. The techniques employed are applicable to a variety of domains where models or simulations are required.

  7. Diverter AI based decision aid, phases 1 and 2

    NASA Technical Reports Server (NTRS)

    Sexton, George A.; Bayles, Scott J.; Patterson, Robert W.; Schulke, Duane A.; Williams, Deborah C.

    1989-01-01

    It was determined that a system to incorporate artificial intelligence (AI) into airborne flight management computers is feasible. The AI functions that would be most useful to the pilot are to perform situational assessment, evaluate outside influences on the contemplated rerouting, perform flight planning/replanning, and perform maneuver planning. A study of the software architecture and software tools capable of demonstrating Diverter was also made. A skeletal planner known as the Knowledge Acquisition Development Tool (KADET), which is a combination script-based and rule-based system, was used to implement the system. A prototype system was developed which demonstrates advanced in-flight planning/replanning capabilities.

  8. AiGERM: A logic programming front end for GERM

    NASA Technical Reports Server (NTRS)

    Hashim, Safaa H.

    1990-01-01

    AiGerm (Artificially Intelligent Graphical Entity Relation Modeler) is a relational data base query and programming language front end for MCC (Mission Control Center)/STP's (Space Test Program) Germ (Graphical Entity Relational Modeling) system. It is intended as an add-on component of the Germ system to be used for navigating very large networks of information. It can also function as an expert system shell for prototyping knowledge-based systems. AiGerm provides an interface between the programming language and Germ.

  9. Monte Carlo study of receptor-lipid raft formation on a cell membrane

    NASA Astrophysics Data System (ADS)

    Yu-Yang, Paul; Srinivas Reddy, A.; Raychaudhuri, Subhadip

    2012-02-01

    Receptors are cell surface molecules that bind with extracellular ligand molecules leading to propagation of downstream signals and cellular activation. Even though ligand binding-induced formation of receptor-lipid rafts has been implicated in such a process, the formation mechanism of such large stable rafts is not understood. We present findings from our Monte Carlo (MC) simulations involving (i) receptor interaction with the membrane lipids and (ii) lipid-lipid interactions between raft forming lipids. We have developed a hybrid MC simulation method that combines a probabilistic MC simulation with an explicit free energy-based MC scheme. Some of the lipid-mediated interactions, such as the cholesterol-lipid interactions, are simulated in an implicit way. We examine the effect of varying attractive interactions between raft forming lipids and ligand-bound receptors and show that strong coupling between receptor-receptor and receptor-sphingolipid molecules generate raft formation similar to that observed in recent biological experiments. We study the effect of variation of receptor affinity for ligands (as happens in adaptive immune cells) on raft formation. Such affinity dependence in receptor-lipid raft formation provides insight into important problems in B cell biology.

  10. Calcium signals drive cell shape changes during zebrafish midbrain-hindbrain boundary formation.

    PubMed

    Sahu, Srishti U; Visetsouk, Mike R; Garde, Ryan J; Hennes, Leah; Kwas, Constance; Gutzman, Jennifer H

    2017-02-01

    One of the first morphogenetic events in the vertebrate brain is the formation of the highly conserved midbrain-hindbrain boundary (MHB). Specific cell shape changes occur at the point of deepest constriction of the MHB, the midbrain-hindbrain boundary constriction (MHBC), and are critical for proper MHB formation. These cell shape changes are controlled by non-muscle myosin II (NMII) motor proteins which are tightly regulated via the phosphorylation of their associated myosin regulatory light chains (MRLC). However, the upstream signaling pathways that initiate the regulation of NMII to mediate cell shape changes during MHB morphogenesis are not known. We show that intracellular calcium signals are critical for the regulation of cell shortening during initial MHB formation. We demonstrate that the MHB region is poised to respond to calcium transients that occur in the MHB at the onset of MHB morphogenesis and that calcium mediates phosphorylation of MRLC specifically in MHB tissue. Our results indicate that calmodulin 1a (calm1a), expressed specifically in the MHB, and myosin light chain kinase (MLCK), together mediate MHBC cell length. Our data suggest that modulation of NMII activity by calcium is critical for proper regulation of cell length to determine embryonic brain shape during development.

  11. Rapid formation of cell-particle complexes via dielectrophoretic manipulation for the detection of surface antigens.

    PubMed

    Horii, Takuma; Yamamoto, Masashi; Yasukawa, Tomoyuki; Mizutani, Fumio

    2014-11-15

    A rapid and simple method for the fabrication of the island patterns with particles and cells was applied to detect the presence of specific antigens on the cell surface. An upper interdigitated microband array (IDA) electrode was mounted on a lower substrate with the same design to fabricate a microfluidic-channel device for dielectrophoretic manipulation. The electrode grid structure was fabricated by rotating the upper template IDA by 90° relative to the lower IDA. A suspension of anti-CD33 modified particles and HL-60 cells was introduced into the channel. An AC electrical signal (typically 20 V peak-to-peak, 100 kHz) was then applied to the bands of the upper and lower IDAs, resulting in the formation of island patterns at the intersections with low electric fields. Immunoreactions between the antibodies immobilized on the accumulated particles and the CD33 present on the surface of the cells led to the formation of complexes comprising corresponding antigen-antibody pairs. Non-specific pairs accumulated at the intersection, which did not form complexes, were then dispersed after removal of the applied field. The time required for the detection of the formation/dispersion of the complexes is as short as 6 min in the present procedure. Furthermore, this novel cell binding assay does not require pretreatment such as target labeling or washing of the unbound cells.

  12. Formation of Lignans(-)-Secoisolariciresinol and (-)-Matairesinol with Forsythia intermedia Cell-Free Extracts

    NASA Technical Reports Server (NTRS)

    Umezawa, Toshiaki; Davin, Laurence B.; Lewis, Norman G.

    1991-01-01

    In vivo labeling experiments of Forsythia intermedia plant tissue with [8-(C-14)]- and [9,9-(2)H2,OC(2)H3]coniferyl alcohols revealed that the lignans, (-)-secoisolariciresinol and (-)-matairesinol, were derived from two coniferyl alcohol molecules; no evidence for the formation of the corresponding (+)-enantiomers was found. Administration of (+/-)-[Ar-(H-3)] secoisolariciresinols to excised shoots of F.intermedia resulted in a significant conversion into (-)-matairesinol; again, the (+)-antipode was not detected. Experiments using cell-free extracts of F.intermedia confirmed and extended these findings. In the presence of NAD(P)H and H2O2, the cell-free extracts catalyzed the formation of (-)- secoisolariciresinol, with either [8-(C-14)]- or [9,9-(2)H2,OC(2)H3]coniferyl alcohols as substrates. The (+)- enantiomer was not formed. Finally, when either (-)-[Ar-(H-3)] or (+/-)-[Ar-(H-2)]secoisolariciresinols were used as substrates, in the presence of NAD(P), only (-)- and not (+)-matairesinol formation occurred. The other antipode, (+)-secoisolariciresinol, did not serve as a substrate for the formation of either (+)- or (-)-matairesinol. Thus, in F.intermedia, the formation of the lignan, (-)-secoisolariciresinol, occurs under strict stereochemical control, in a reaction or reactions requiring NAD(P)H and H2O2 as cofactors. This stereoselectivity is retained in the subsequent conversion into (-)-matairesinol, since (+)-secoisolariciresinol is not a substrate. These are the first two enzymes to be discovered in lignan formation.

  13. Embryonic stem cell-derived granulosa cells participate in ovarian follicle formation in vitro and in vivo.

    PubMed

    Woods, Dori C; White, Yvonne A R; Niikura, Yuichi; Kiatpongsan, Sorapop; Lee, Ho-Joon; Tilly, Jonathan L

    2013-05-01

    Differentiating embryonic stem cells (ESCs) can form ovarian follicle-like structures in vitro, consisting of an oocyte-like cell surrounded by somatic cells capable of steroidogenesis. Using a dual-fluorescence reporter system in which mouse ESCs express green fluorescent protein (GFP) under the control of a germ cell-specific Pou5f1 gene promoter and red fluorescent protein (Discosoma sp red [DsRed]) driven by the granulosa cell-specific Forkhead box L2 (Foxl2) gene promoter, we first confirmed in vitro formation of follicle-like structures containing GFP-positive cells surrounded by DsRed-positive cells. Isolated DsRed-positive cells specified from ECSs exhibited a gene expression profile consistent with granulosa cells, as revealed by the detection of messenger RNAs (mRNAs) for Foxl2, follistatin (Fst), anti-Müllerian hormone (Amh), and follicle-stimulating hormone receptor (Fshr) as well as by production of both progesterone and estradiol. In addition, treatment of isolated DsRed-expressing cells with follicle-stimulating hormone (FSH) significantly increased estradiol production over basal levels, confirming the presence of functional FSH receptors in these cells. Last, ESC-derived DsRed-positive cells injected into neonatal mouse ovaries became incorporated within the granulosa cell layer of immature follicles. These studies demonstrate that Foxl2-expressing ovarian somatic cells derived in vitro from differentiating ESCs express granulosa cell markers, actively associate with germ cells in vitro, synthesize steroids, respond to FSH, and participate in folliculogenesis in vivo.

  14. An integrin-ILK-microtubule network orients cell polarity and lumen formation in glandular epithelium.

    PubMed

    Akhtar, Nasreen; Streuli, Charles H

    2013-01-01

    The extracellular matrix has a crucial role in determining the spatial orientation of epithelial polarity and the formation of lumens in glandular tissues; however, the underlying mechanisms remain elusive. By using Cre–Lox deletion we show that β1 integrins are required for normal mammary gland morphogenesis and lumen formation, both in vivo and in a three-dimensional primary culture model in which epithelial cells directly contact a basement membrane. Downstream of basement membrane β1 integrins, Rac1 is not involved; however, ILK is needed to polarize microtubule plus ends at the basolateral membrane and disrupting each of these components prevents lumen formation. The integrin–microtubule axis is necessary for the endocytic removal of apical proteins from the basement-membrane–cell interface and for internal Golgi positioning. We propose that this integrin signalling network controls the delivery of apical components to the correct surface and thereby governs the orientation of polarity and development of lumens.

  15. Formation of thin films of organic-inorganic perovskites for high-efficiency solar cells.

    PubMed

    Stranks, Samuel D; Nayak, Pabitra K; Zhang, Wei; Stergiopoulos, Thomas; Snaith, Henry J

    2015-03-09

    Organic-inorganic perovskites are currently one of the hottest topics in photovoltaic (PV) research, with power conversion efficiencies (PCEs) of cells on a laboratory scale already competing with those of established thin-film PV technologies. Most enhancements have been achieved by improving the quality of the perovskite films, suggesting that the optimization of film formation and crystallization is of paramount importance for further advances. Here, we review the various techniques for film formation and the role of the solvents and precursors in the processes. We address the role chloride ions play in film formation of mixed-halide perovskites, which is an outstanding question in the field. We highlight the material properties that are essential for high-efficiency operation of solar cells, and identify how further improved morphologies might be achieved.

  16. Palladium deuteride formation in the cathode of an electrochemical cell: An in situ neutron diffraction study

    SciTech Connect

    Rotella, F.J.; Richardson, J.W. Jr.; Redey, L.; Felcher, G.P.; Hitterman, R.L.; Kleb, R.

    1991-12-31

    In this report, neutron diffraction of palladium cathodes is utilized to reveal palladium deuteride formation within the crystal structure of the metal. The experiment described in this report demonstrates the efficacy of neutron powder diffraction as a tool for structural studies of metal deuterides/hydrides and the feasibility of in situ diffraction measurements from a working electrochemical cell. (JL)

  17. Palladium deuteride formation in the cathode of an electrochemical cell: An in situ neutron diffraction study

    SciTech Connect

    Rotella, F.J.; Richardson, J.W. Jr.; Redey, L.; Felcher, G.P.; Hitterman, R.L.; Kleb, R.

    1991-01-01

    In this report, neutron diffraction of palladium cathodes is utilized to reveal palladium deuteride formation within the crystal structure of the metal. The experiment described in this report demonstrates the efficacy of neutron powder diffraction as a tool for structural studies of metal deuterides/hydrides and the feasibility of in situ diffraction measurements from a working electrochemical cell. (JL)

  18. PERP regulates enamel formation via effects on cell–cell adhesion and gene expression

    PubMed Central

    Jheon, Andrew H.; Mostowfi, Pasha; Snead, Malcolm L.; Ihrie, Rebecca A.; Sone, Eli; Pramparo, Tiziano; Attardi, Laura D.; Klein, Ophir D.

    2011-01-01

    Little is known about the role of cell–cell adhesion in the development of mineralized tissues. Here we report that PERP, a tetraspan membrane protein essential for epithelial integrity, regulates enamel formation. PERP is necessary for proper cell attachment and gene expression during tooth development, and its expression is controlled by P63, a master regulator of stratified epithelial development. During enamel formation, PERP is localized to the interface between the enamel-producing ameloblasts and the stratum intermedium (SI), a layer of cells subjacent to the ameloblasts. Perp-null mice display dramatic enamel defects, which are caused, in part, by the detachment of ameloblasts from the SI. Microarray analysis comparing gene expression in teeth of wild-type and Perp-null mice identified several differentially expressed genes during enamel formation. Analysis of these genes in ameloblast-derived LS8 cells upon knockdown of PERP confirmed the role for PERP in the regulation of gene expression. Together, our data show that PERP is necessary for the integrity of the ameloblast–SI interface and that a lack of Perp causes downregulation of genes that are required for proper enamel formation. PMID:21285247

  19. Defective PDI release from platelets and endothelial cells impairs thrombus formation in Hermansky-Pudlak syndrome.

    PubMed

    Sharda, Anish; Kim, Sarah H; Jasuja, Reema; Gopal, Srila; Flaumenhaft, Robert; Furie, Barbara C; Furie, Bruce

    2015-03-05

    Protein disulfide isomerase (PDI), secreted from platelets and endothelial cells after injury, is required for thrombus formation. The effect of platelet and endothelial cell granule contents on PDI-mediated thrombus formation was studied by intravital microscopy using a mouse model of Hermansky-Pudlak syndrome in which platelet dense granules are absent. Platelet deposition and fibrin generation were nearly absent, and extracellular PDI was significantly reduced in HPS6(-/-) mice after vascular injury. HPS6(-/-) platelets displayed impaired PDI secretion and impaired exocytosis of α granules, lysosomes, and T granules due to decreased sensitivity to thrombin, but these defects could be corrected by addition of subthreshold amounts of adenosine 5'-diphosphate (ADP). Human Hermansky-Pudlak syndrome platelets demonstrated similar characteristics. Infusion of wild-type platelets rescued thrombus formation in HPS6(-/-) mice. Human umbilical vein endothelial cells in which the HPS6 gene was silenced displayed impaired PDI secretion and exocytosis of Weibel-Palade bodies. Defective thrombus formation in Hermansky-Pudlak syndrome, associated with impaired exocytosis of residual granules in endothelial cells and platelets, the latter due to deficiency of ADP, is characterized by a defect in T granule secretion, a deficiency in extracellular PDI secretion, and impaired fibrin generation and platelet aggregation. Hermansky-Pudlak syndrome is an example of a hereditary disease whereby impaired PDI secretion contributes to a bleeding phenotype.

  20. Jin Fu Kang Oral Liquid Inhibits Lymphatic Endothelial Cells Formation and Migration

    PubMed Central

    Wang, Dan; Tang, Jie

    2016-01-01

    Lung cancer is the leading cause of cancer-related deaths worldwide. Jin Fu Kang (JFK), an oral liquid prescription of Chinese herbal drugs, has been clinically available for the treatment of non-small cell lung cancer (NSCLC). Lymphangiogenesis is a primary event in the process of cancer development and metastasis, and the formation and migration of lymphatic endothelial cells (LECs) play a key role in the lymphangiogenesis. To assess the activity of stromal cell-derived factor-1 (SDF-1) and the coeffect of SDF-1 and vascular endothelial growth factor-C (VEGF-C) on the formation and migration of LECs and clarify the inhibitory effects of JFK on the LECs, the LECs were differentiated from CD34+/VEGFR-3+ endothelial progenitor cells (EPCs), and JFK-containing serums were prepared from rats. SDF-1 and VEGF-C both induced the differentiation of CD34+/VEGFR-3+ EPCs towards LECs and enhanced the LECs migration. Couse of SDF-1 and VEGF-C displayed an additive effect on the LECs formation but not on their migration. JFK inhibited the formation and migration of LECs, and the inhibitory effects were most probably via regulation of the SDF-1/CXCR4 and VEGF-C/VEGFR-3 axes. The current finding suggested that JFK might inhibit NSCLC through antilymphangiogenesis and also provided a potential to discover antilymphangiogenesis agents from natural resources. PMID:27698675

  1. Synaptotagmin-Like Proteins Control Formation of a Single Apical Membrane Domain in Epithelial Cells

    PubMed Central

    Gálvez-Santisteban, Manuel; Rodriguez-Fraticelli, Alejo E.; Bryant, David M.; Vergarajauregui, Silvia; Yasuda, Takao; Bañón-Rodríguez, Inmaculada; Bernascone, Ilenia; Datta, Anirban; Spivak, Natalie; Young, Kitty; Slim, Christiaan L.; Brakeman, Paul R.; Fukuda, Mitsunori; Mostov, Keith E.; Martín-Belmonte, Fernando

    2012-01-01

    SUMMARY The formation of epithelial tissues requires both the generation of apical-basal polarity and the co-ordination of this polarity between neighboring cells to form a central lumen. During de novo lumen formation, vectorial membrane transport contributes to formation of a singular apical membrane, resulting in contribution of each cell to only a single lumen. Here, from a functional screen for genes required for 3D epithelial architecture we identify key roles for Synaptotagmin-like proteins 2-a and 4-a (Slp2-a/4-a) in generation of a single apical surface per cell. Slp2-a localizes to the luminal membrane in a PI(4,5)P2-dependent manner, where it targets Rab27-loaded vesicles to initiate a single lumen. Vesicle tethering and fusion is controlled by Slp4-a, in conjunction with Rab27/Rab3/Rab8 and the SNARE Syntaxin-3. Together, Slp2-a/4-a co-ordinate the spatiotemporal organization of vectorial apical transport to ensure only a single apical surface, and thus formation of a single lumen, occurs per cell. PMID:22820376

  2. Inhibition of gold nanoparticles (AuNPs) on pathogenic biofilm formation and invasion to host cells

    PubMed Central

    Yu, Qilin; Li, Jianrong; Zhang, Yueqi; Wang, Yufan; Liu, Lu; Li, Mingchun

    2016-01-01

    Owing to the growing infectious diseases caused by eukaryotic and prokaryotic pathogens, it is urgent to develop novel antimicrobial agents against clinical pathogenic infections. Biofilm formation and invasion into the host cells are vital processes during pathogenic colonization and infection. In this study, we tested the inhibitory effect of Au nanoparticles (AuNPs) on pathogenic growth, biofilm formation and invasion. Interestingly, although the synthesized AuNPs had no significant toxicity to the tested pathogens, Candida albicans and Pseudomonas aeruginosa, the nanoparticles strongly inhibited pathogenic biofilm formation and invasion to dental pulp stem cells (DPSCs). Further investigations revealed that AuNPs abundantly bound to the pathogen cells, which likely contributed to their inhibitory effect on biofilm formation and invasion. Moreover, treatment of AuNPs led to activation of immune response-related genes in DPSCs, which may enhance the activity of host immune system against the pathogens. Zeta potential analysis and polyethylene glycol (PEG)/polyethyleneimine (PEI) coating tests further showed that the interaction between pathogen cells and AuNPs is associated with electrostatic attractions. Our findings shed novel light on the application of nanomaterials in fighting against clinical pathogens, and imply that the traditional growth inhibition test is not the only way to evaluate the drug effect during the screening of antimicrobial agents. PMID:27220400

  3. Free Energies of Formation Measurements on Solid-State Electrochemical Cells

    ERIC Educational Resources Information Center

    Rollino, J. A.; Aronson, S.

    1972-01-01

    A simple experiment is proposed that can provide the student with some insight into the chemical properties of solids. It also demonstrates the relationship between the Gibbs free energy of formation of an ionic solid and the emf of an electrochemical cell. (DF)

  4. Peptidal Sex Hormones Inducing Conjugation Tube Formation in Compatible Mating-Type Cells of Tremella mesenterica.

    PubMed

    Sakagami, Y; Yoshida, M; Isogai, A; Suzuki, A

    1981-06-26

    The pair of peptidal sex hormones (tremerogen A-10 and tremerogen a-13) that induce conjugation tube formation in compatible type cells (A and a types) of Tremella mesenterica were isolated. Tremerogen A-10 is a dodecapeptide and tremerogen a-13, a tridecapeptide. In both peptides, the sulfiydryl group of the cysteines at the carboxyl terminus was blocked by farnesyl moieties.

  5. Formation of binucleated myocardial cells in the neonatal rat. An index for growth hypertrophy.

    PubMed

    Clubb, F J; Bishop, S P

    1984-05-01

    The purposes of this study were to characterize myocardial cell growth in neonatal rats and investigate the mechanism of binucleation in myocardial cells. To test the hypothesis that binucleated myocardial cells result from karyokinesis without cytokinesis, experiments were designed to measure the rate of DNA synthesis and the percentage of binucleated myocardial cells in neonatal rats during growth. Estimates of myocardial cell nuclear divisions were obtained from rats pulsed with tritiated thymidine at 17 days of gestation. Autoradiograms were prepared from isolated myocardial cells of rats killed at various ages postpartum, and the number of developed silver halide grains over myocardial cell nuclei was calculated. This estimated the mitotic activity of nuclei. To determine myocardial cell DNA synthesis postpartum, another set of rats were injected at various time periods with 4 hourly doses of tritiated thymidine, and hearts were fixed by perfusion 1 hour later. Labeling index of myocardial cells was calculated (labeled/total myocardial cells) from autoradiograms prepared on 1 micron thick, methacrylate-embedded heart cross-sections. Results of this study indicated that the growth of myocardial cells in the neonatal period can be divided into three phases: (a) a hyperplastic phase, (b) a transitional phase, and (c) a hypertrophic phase. Binucleation of myocardial cells was not due to fusion of mononucleated cells, because there was continued DNA synthesis in the neonatal hearts, reflected by continued incorporation of tritiated thymidine; in addition, the grain counts per nucleus of the binucleated myocardial cells were half that of mononucleated cells; nor was binucleation due to amitotic splitting of single nuclei, since binucleated myocardial cells had similar grain counts over each nucleus. We conclude that the formation of binucleated myocardial cells is an early indicator of growth hypertrophy in the neonatal rat and a result of mitosis without

  6. Model system for studies on bone matrix formation by osteogenic cells in microgravity

    NASA Astrophysics Data System (ADS)

    Quinton, Todd M.; Fattaey, Heideh K.; Motaffaf, Farzaneh; Johnson, Terry C.

    1998-01-01

    A considerable amount of attention has been focused on the physiological factors that are responsible for the reduction of bone mineralization and mass during prolonged periods in the microgravity environment. Although bone mineralization can be reduced by one percent per month as shown to result from shuttle flights and Mir habitation, the reasons for this phenomenon remain unclear. Changes in specific markers of bone cells upon differentiation indicate that the induction of bone matrix formation is dependent upon these cells reaching confluency. In our laboratory, we have isolated a reversible inhibitor of cellular growth (CeReS-18) that could be important in cell contact inhibition and thus may mimic the signals involved in growth confluency. Preliminary experiments with osteogenic cells have revealed the potential capability of CeReS-18 to inhibit these cells in a reversible manner. We are developing a series of studies, designed at the cellular level, to quantitatively measure the production of bone matrix by osteogenic cells propagated in culture. The use of CeReS-18 would facilitate the study of several factors being assessed regarding matrix formation including the rate of cell population density, hormone induction events, calcium availability, and cell cycle arest. The studies are being conducted in a manner that will allow comparable measurements in the microgravity environment with flight hardware designed and deployed by BioServe Space Technologies.

  7. The enamel matrix derivative (Emdogain) enhances human tongue carcinoma cells gelatinase production, migration and metastasis formation.

    PubMed

    Laaksonen, Matti; Suojanen, Juho; Nurmenniemi, Sini; Läärä, Esa; Sorsa, Timo; Salo, Tuula

    2008-08-01

    Enamel matrix derivative Emdogain (EMD) is widely used in periodontal treatment to regenerate lost connective tissue and to improve the attachment of the teeth. Gelatinases (MMP-2 and -9) have an essential role in the promotion and progression of oral cancer growth and metastasis formation. We studied the effects of EMD on human tongue squamous cell carcinoma (HSC-3) cells in vitro and in vivo. In vitro, EMD (100 microg/ml and 200 microg/ml) remarkably induced the MMP-2 and -9 production from HSC-3 cells analysed by zymography and enzyme-linked immunosorbent assay. EMD also slightly induced the MMP-2 and -9 production from benign human mucosal keratinocytes (HMK). Furthermore, EMD clearly induced the transmigration of HSC-3 cells but had no effect on the HMK migration in transwell assays. The in vitro wound closure of HSC-3 cells was notably accelerated by EMD, whereas it had only minor effect on the wound closure of HMKs. The migration of both cell lines was inhibited by a selective cyclic anti-gelatinolytic peptide CTT-2. EMD had no effect on HSC-3 cell proliferation or apoptosis and only a limited effect on cell attachment to various extracellular matrix components. The in vivo mice experiment revealed that EMD substantially induced HSC-3 xenograft metastasis formation. Our results suggest that the use of EMD for patients with oral mucosal carcinomas or premalignant lesions should be carefully considered, possibly avoided.

  8. Development of Large-Format Lithium-Ion Cells with Silicon Anode and Low Flammable Electrolyte

    NASA Technical Reports Server (NTRS)

    Wu, James J.; Hernandez-Lugo, D. M.; Smart, M. C.; Ratnakumar, B. V.; Miller, T. B.; Lvovich, V. F.; Lytle, J. K.

    2014-01-01

    NASA is developing safe, high energy and high capacity lithium-ion cell designs and batteries for future missions under NASAs Advanced Space Power System (ASPS) project. Advanced cell components, such as high specific capacity silicon anodes and low-flammable electrolytes have been developed for improving the cell specific energy and enhancing safety. To advance the technology readiness level, we have developed large-format flight-type hermetically sealed battery cells by incorporating high capacity silicon anodes, commercially available lithium nickel, cobalt, aluminum oxide (NCA) cathodes, and low-flammable electrolytes. In this report, we will present the performance results of these various battery cells. In addition, we will also discuss the post-test cell analysis results as well.

  9. Rosette formation with sheep erythrocytes--a possible T-cell marker in the pig.

    PubMed

    Escajadillo, C; Binns, R M

    1975-01-01

    A proportion of pig lymphocytes form rosettes with sheep erythrocytes. Factors affecting their demonstration have been investigated, and a standard technique defined. Rosette-forming lymphocytes lacked surface immunoglobulin detected by immunofluorescence and formation of rosettes was not inhibited by anti-immunoglobulin or anti-PLA sera, but was by anti-thymus serum. Of 18 species' erythrocytes tested only sheep, Barbary sheep and Mouflon erythrocytes formed rosettes in similar percentages. Fetal sheep erythrocytes formed no rosettes at 6o days of gestation and developed adult levels by term. Rosettes were formed by the majority of thymus cells, by only few bone marrow cells and by intermediate proportions of cells in other lymphoid tissues correlating with the probable order of T cell content. In pig fetuses, thymus contained postnatal levels of rosette-forming cells by 69 days, when such cells were not detected in other tissues. These data support the contention that SRBC rosettes are formed by T lymphocytes.

  10. Matrix formation is enhanced in co-cultures of human meniscus cells with bone marrow stromal cells.

    PubMed

    Matthies, Norah-Faye; Mulet-Sierra, Aillette; Jomha, Nadr M; Adesida, Adetola B

    2013-12-01

    The ultimate aim of this study was to assess the feasibility of using human bone marrow stromal cells (BMSCs) to supplement meniscus cells for meniscus tissue engineering and regeneration. Human menisci were harvested from three patients undergoing total knee replacements. Meniscus cells were released from the menisci after collagenase treatment. BMSCs were harvested from the iliac crest of three patients and were expanded in culture until passage 2. Primary meniscus cells and BMSCs were co-cultured in vitro in three-dimensional (3D) pellet culture at three different cell-cell ratios for 3 weeks under normal (21% O2 ) or low (3% O2 ) oxygen tension in the presence of serum-free chondrogenic medium. Pure BMSCs and pure meniscus cell pellets served as control groups. The tissue generated was assessed biochemically, histochemically and by quantitative RT-PCR. Co-cultures of primary meniscus cells and BMSCs resulted in tissue with increased (1.3-1.7-fold) deposition of proteoglycan (GAG) extracellular matrix (ECM) relative to tissues derived from BMSCs or meniscus cells alone under 21% O2 . GAG matrix formation was also enhanced (1.3-1.6-fold) under 3% O2 culture conditions. Alcian blue staining of generated tissue confirmed increased deposition of GAG-rich matrix. mRNA expression of type I collagen (COL1A2), type II collagen (COL2A1) and aggrecan were upregulated in co-cultured pellets. However, SOX9 and HIF-1α mRNA expression were not significantly modulated by co-culture. Co-culture of primary meniscus cells with BMSCs resulted in increased ECM formation. Co-delivery of meniscus cells and BMSCs can, in principle, be used in tissue engineering and regenerative medicine strategies to repair meniscus defects.

  11. Loss of E-cadherin disrupts ovarian epithelial inclusion cyst formation and collective cell movement in ovarian cancer cells

    PubMed Central

    Choi, Pui-Wah; Yang, Junzheng; Ng, Shu-Kay; Feltmate, Colleen; Muto, Michael G.; Hasselblatt, Kathleen; Lafferty-Whyte, Kyle; JeBailey, Lellean; MacConaill, Laura; Welch, William R.; Fong, Wing-Ping; Berkowitz, Ross S.; Ng, Shu-Wing

    2016-01-01

    Increased inclusion cyst formation in the ovary is associated with ovarian cancer development. We employed in vitro three-dimensional (3D) organotypic models formed by normal human ovarian surface epithelial (OSE) cells and ovarian cancer cells to study the morphologies of normal and cancerous ovarian cortical inclusion cysts and the molecular changes during their transitions into stromal microenvironment. When compared with normal cysts that expressed tenascin, the cancerous cysts expressed high levels of laminin V and demonstrated polarized structures in Matrigel; and the cancer cells migrated collectively when the cyst structures were positioned in a stromal-like collagen I matrix. The molecular markers identified in the in vitro 3D models were verified in clinical samples. Network analysis of gene expression of the 3D structures indicates concurrent downregulation of transforming growth factor beta pathway genes and high levels of E-cadherin and microRNA200 (miR200) expression in the cancerous cysts and the migrating cancer cells. Transient silencing of E-cadherin expression in ovarian cancer cells disrupted cyst structures and inhibited collective cell migration. Taken together, our studies employing 3D models have shown that E-cadherin is crucial for ovarian inclusion cyst formation and collective cancer cell migration. PMID:26684027

  12. Characterization and Localization of Insoluble Organic Matrices Associated with Diatom Cell Walls: Insight into Their Roles during Cell Wall Formation

    PubMed Central

    Tesson, Benoit; Hildebrand, Mark

    2013-01-01

    Organic components associated with diatom cell wall silica are important for the formation, integrity, and function of the cell wall. Polysaccharides are associated with the silica, however their localization, structure, and function remain poorly understood. We used imaging and biochemical approaches to describe in detail characteristics of insoluble organic components associated with the cell wall in 5 different diatom species. Results show that an insoluble organic matrix enriched in mannose, likely the diatotepum, is localized on the proximal surface of the silica cell wall. We did not identify any organic matrix embedded within the silica. We also identified a distinct material consisting of glucose polymer with variable localization depending on the species. In some species this component was directly involved in the morphogenesis of silica structure while in others it appeared to be only a structural component of the cell wall. A novel glucose-rich structure located between daughter cells during division was also identified. This work for the first time correlates the structure, composition, and localization of insoluble organic matrices associated with diatom cell walls. Additionally we identified a novel glucose polymer and characterized its role during silica structure formation. PMID:23626714

  13. Identification of poultry meat-derived fatty acids functioning as quorum sensing signal inhibitors to autoinducer-2 (AI-2).

    PubMed

    Widmer, K W; Soni, K A; Hume, M E; Beier, R C; Jesudhasan, P; Pillai, S D

    2007-11-01

    Autoinducer-2 (AI-2) is a compound that plays a key role in bacterial cell-to-cell communication (quorum sensing). Previous research has shown certain food matrices inhibit this signaling compound. Using the reporter strain, Vibrio harveyi BB170, quorum-sensing inhibitors contained in poultry meat wash (PMW) samples were characterized by molecular weight and hydrophobic properties using liquid chromatography systems. Most fractions that demonstrated AI-2 inhibition were 13.7 kDa or less, and had hydrophobic properties. Hexane was used to extract inhibitory compounds from a PMW preparation and the extract was further separated by gas chromatography (GC). Several fatty acids were identified and quantified. Linoleic acid, oleic acid, palmitic acid, and stearic acid were each tested for inhibition at 0.1, 1, and 10 mM concentrations. All samples expressed AI-2 inhibition (ranging from approximately 25% to 99%). Fatty acids, combined in concentrations equivalent to those determined by GC analysis, expressed inhibition at 59.5%, but higher combined concentrations (10- and 100-fold) had inhibition at 84.4% and 69.5%, respectively. The combined fatty acids (100-fold) did not demonstrate a substantial decrease in colony plate counts, despite presenting high AI-2 inhibition. These fatty acids, through modulating quorum sensing by inhibition, may offer a unique means to control foodborne pathogens and reduce microbial spoilage.

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

    PubMed

    Pitkänen, A; Amaral, D G

    1993-05-01

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

  15. Total synthesis of a biotinylated rocaglate: Selective targeting of the translation factors eIF4AI/II.

    PubMed

    Chambers, Jennifer M; Lindqvist, Lisa M; Savage, G Paul; Rizzacasa, Mark A

    2016-01-15

    The total synthesis of a biotinylated derivative of methyl rocaglate is described. This compound was accessed from synthetic methyl rocaglate (2) via formation of the propargyl amide and subsequent click reaction with a biotin azide. Affinity purification revealed that biotinylated rocaglate (8) and methyl rocaglate (2) bind with high specificity to translation factors eIF4AI/II. This remarkable selectivity is in line with that found for the more complex rocaglate silvestrol (3).

  16. Osterix-cre labeled progenitor cells contribute to the formation and maintenance of the bone marrow stroma.

    PubMed

    Liu, Yaling; Strecker, Sara; Wang, Liping; Kronenberg, Mark S; Wang, Wen; Rowe, David W; Maye, Peter

    2013-01-01

    We have carried out fate mapping studies using Osterix-EGFPCre and Osterix-CreERt animal models and found Cre reporter expression in many different cell types that make up the bone marrow stroma. Constitutive fate mapping resulted in the labeling of different cellular components located throughout the bone marrow, whereas temporal fate mapping at E14.5 resulted in the labeling of cells within a region of the bone marrow. The identity of cell types marked by constitutive and temporal fate mapping included osteoblasts, adipocytes, vascular smooth muscle, perineural, and stromal cells. Prolonged tracing of embryonic precursors labeled at E14.5dpc revealed the continued existence of their progeny up to 10 months of age, suggesting that fate mapped, labeled embryonic precursors gave rise to long lived bone marrow progenitor cells. To provide further evidence for the marking of bone marrow progenitors, bone marrow cultures derived from Osterix-EGFPCre/Ai9 mice showed that stromal cells retained Cre reporter expression and yielded a FACS sorted population that was able to differentiate into osteoblasts, adipocytes, and chondrocytes in vitro and into osteoblasts, adipocytes, and perivascular stromal cells after transplantation. Collectively, our studies reveal the developmental process by which Osterix-Cre labeled embryonic progenitors give rise to adult bone marrow progenitors which establish and maintain the bone marrow stroma.

  17. ZnO Nanoparticles Affect Bacillus subtilis Cell Growth and Biofilm Formation.

    PubMed

    Hsueh, Yi-Huang; Ke, Wan-Ju; Hsieh, Chien-Te; Lin, Kuen-Song; Tzou, Dong-Ying; Chiang, Chao-Lung

    2015-01-01

    Zinc oxide nanoparticles (ZnO NPs) are an important antimicrobial additive in many industrial applications. However, mass-produced ZnO NPs are ultimately disposed of in the environment, which can threaten soil-dwelling microorganisms that play important roles in biodegradation, nutrient recycling, plant protection, and ecological balance. This study sought to understand how ZnO NPs affect Bacillus subtilis, a plant-beneficial bacterium ubiquitously found in soil. The impact of ZnO NPs on B. subtilis growth, FtsZ ring formation, cytosolic protein activity, and biofilm formation were assessed, and our results show that B. subtilis growth is inhibited by high concentrations of ZnO NPs (≥ 50 ppm), with cells exhibiting a prolonged lag phase and delayed medial FtsZ ring formation. RedoxSensor and Phag-GFP fluorescence data further show that at ZnO-NP concentrations above 50 ppm, B. subtilis reductase activity, membrane stability, and protein expression all decrease. SDS-PAGE Stains-All staining results and FT-IR data further demonstrate that ZnO NPs negatively affect exopolysaccharide production. Moreover, it was found that B. subtilis biofilm surface structures became smooth under ZnO-NP concentrations of only 5-10 ppm, with concentrations ≤ 25 ppm significantly reducing biofilm formation activity. XANES and EXAFS spectra analysis further confirmed the presence of ZnO in co-cultured B. subtilis cells, which suggests penetration of cell membranes by either ZnO NPs or toxic Zn+ ions from ionized ZnO NPs, the latter of which may be deionized to ZnO within bacterial cells. Together, these results demonstrate that ZnO NPs can affect B. subtilis viability through the inhibition of cell growth, cytosolic protein expression, and biofilm formation, and suggest that future ZnO-NP waste management strategies would do well to mitigate the potential environmental impact engendered by the disposal of these nanoparticles.

  18. ZnO Nanoparticles Affect Bacillus subtilis Cell Growth and Biofilm Formation

    PubMed Central

    Hsueh, Yi-Huang; Ke, Wan-Ju; Hsieh, Chien-Te; Lin, Kuen-Song; Tzou, Dong-Ying; Chiang, Chao-Lung

    2015-01-01

    Zinc oxide nanoparticles (ZnO NPs) are an important antimicrobial additive in many industrial applications. However, mass-produced ZnO NPs are ultimately disposed of in the environment, which can threaten soil-dwelling microorganisms that play important roles in biodegradation, nutrient recycling, plant protection, and ecological balance. This study sought to understand how ZnO NPs affect Bacillus subtilis, a plant-beneficial bacterium ubiquitously found in soil. The impact of ZnO NPs on B. subtilis growth, FtsZ ring formation, cytosolic protein activity, and biofilm formation were assessed, and our results show that B. subtilis growth is inhibited by high concentrations of ZnO NPs (≥ 50 ppm), with cells exhibiting a prolonged lag phase and delayed medial FtsZ ring formation. RedoxSensor and Phag-GFP fluorescence data further show that at ZnO-NP concentrations above 50 ppm, B. subtilis reductase activity, membrane stability, and protein expression all decrease. SDS-PAGE Stains-All staining results and FT-IR data further demonstrate that ZnO NPs negatively affect exopolysaccharide production. Moreover, it was found that B. subtilis biofilm surface structures became smooth under ZnO-NP concentrations of only 5–10 ppm, with concentrations ≤ 25 ppm significantly reducing biofilm formation activity. XANES and EXAFS spectra analysis further confirmed the presence of ZnO in co-cultured B. subtilis cells, which suggests penetration of cell membranes by either ZnO NPs or toxic Zn+ ions from ionized ZnO NPs, the latter of which may be deionized to ZnO within bacterial cells. Together, these results demonstrate that ZnO NPs can affect B. subtilis viability through the inhibition of cell growth, cytosolic protein expression, and biofilm formation, and suggest that future ZnO-NP waste management strategies would do well to mitigate the potential environmental impact engendered by the disposal of these nanoparticles. PMID:26039692

  19. Ezrin/Radixin/Moesin proteins and flotillins cooperate to promote uropod formation in T cells.

    PubMed

    Martinelli, Sibylla; Chen, Emily J H; Clarke, Fiona; Lyck, Ruth; Affentranger, Sarah; Burkhardt, Janis K; Niggli, Verena

    2013-01-01

    T cell uropods are enriched in specific proteins including adhesion receptors such as P-selectin glycoprotein ligand-1 (PSGL-1), lipid raft-associated proteins such as flotillins and ezrin/radixin/moesin (ERM) proteins which associate with cholesterol-rich raft domains and anchor adhesion receptors to the actin cytoskeleton. Using dominant mutants and siRNA technology we have tested the interactions among these proteins and their role in shaping the T cell uropod. Expression of wild type (WT) ezrin-EGFP failed to affect the morphology of human T cells or chemokine-induced uropod recruitment of PSGL-1 and flotillin-1 and -2. In contrast, expression of constitutively active T567D ezrin-EGFP induced a motile, polarized phenotype in some of the transfected T cells, even in the absence of chemokine. These cells featured F-actin-rich ruffles in the front and uropod enrichment of PSGL-1 and flotillins. T567D ezrin-EGFP was itself strongly enriched in the rear of the polarized T cells. Uropod formation induced by T567D ezrin-EGFP was actin-dependent as it was attenuated by inhibition of Rho-kinase or myosin II, and abolished by disruption of actin filaments. While expression of constitutively active ezrin enhanced cell polarity, expression of a dominant-negative deletion mutant of ezrin, 1-310 ezrin-EGFP, markedly reduced uropod formation induced by the chemokine SDF-1, T cell front-tail polarity, and capping of PSGL-1 and flotillins. Transfection of T cells with WT or T567D ezrin did not affect chemokine-mediated chemotaxis whereas 1-310 ezrin significantly impaired spontaneous 2D migration and chemotaxis. siRNA-mediated downregulation of flotillins in murine T cells attenuated moesin capping and uropod formation, indicating that ERM proteins and flotillins cooperate in uropod formation. In summary, our results indicate that activated ERM proteins function together with flotillins to promote efficient chemotaxis of T cells by structuring the uropod of migrating T cells.

  20. Novel approach for formation of platelet-like particles from mouse embryonic stem cells without using feeder cells.

    PubMed

    Tsuji, Kayoko; Ohnuma, Masaaki; Jung, Stephanie M; Moroi, Masaaki

    2009-01-01

    Megakaryocytes (MKs) and platelet-like particles (PLPs) have generally been obtained by culturing embryonic stem (ES) cells over feeder cells. However, using feeder cells need many labor-consuming processes and the MK and PLP fractions obtained are often contaminated by such cells and their fragments. Here we describe our new culture system for differentiating mouse ES cells to MKs and PLPs without using feeder cells. ES cells are differentiated to cells with MK-like morphology and properties, including proplatelet formation, high ploidy (>8N), and CD41 expression. The culture medium contained PLPs expressing platelet glycoproteins, CD41 and GPIb. Integrin alpha(IIb)beta(3) of PLPs can be activated by thrombin. Addition of the metalloproteinase inhibitor TAPI-2 to the culture increased the surface expression of GPIbalpha and augmented the adhesion of PLPs to immobilized von Willebrand factor through decreasing the shedding of GPIbalpha. Thus our mouse ES cells culture system is a suitable and efficient method for obtaining MKs and functional PLPs that obviates the need for feeder cells.

  1. Human adipose tissue-derived mesenchymal stem cells abrogate plasmablast formation and induce regulatory B cells independently of T helper cells.

    PubMed

    Franquesa, M; Mensah, F K; Huizinga, R; Strini, T; Boon, L; Lombardo, E; DelaRosa, O; Laman, J D; Grinyó, J M; Weimar, W; Betjes, M G H; Baan, C C; Hoogduijn, M J

    2015-03-01

    Mesenchymal or stromal stem cells (MSC) interact with cells of the immune system in multiple ways. Modulation of the immune system by MSC is believed to be a therapeutic option for autoimmune disease and transplant rejection. In recent years, B cells have moved into the focus of the attention as targets for the treatment of immune disorders. Current B-cell targeting treatment is based on the indiscriminate depletion of B cells. The aim of this study was to examine whether human adipose tissue-derived MSC (ASC) interact with B cells to affect their proliferation, differentiation, and immune function. ASC supported the survival of quiescent B cells predominantly via contact-dependent mechanisms. Coculture of B cells with activated T helper cells led to proliferation and differentiation of B cells into CD19(+) CD27(high) CD38(high) antibody-producing plasmablasts. ASC inhibited the proliferation of B cells and this effect was dependent on the presence of T cells. In contrast, ASC directly targeted B-cell differentiation, independently of T cells. In the presence of ASC, plasmablast formation was reduced and IL-10-producing CD19(+) CD24(high) CD38(high) B cells, known as regulatory B cells, were induced. These results demonstrate that ASC affect B cell biology in vitro, suggesting that they can be a tool for the modulation of the B-cell response in immune disease.

  2. Hydroxide Self-Feeding High-Temperature Alkaline Direct Formate Fuel Cells.

    PubMed

    Li, Yinshi; Sun, Xianda; Feng, Ying

    2017-03-11

    Conventionally, both the thermal degradation of the anion-exchange membrane and the requirement of additional hydroxide for fuel oxidation reaction hinder the development of the high-temperature alkaline direct liquid fuel cells. The present work addresses these two issues by reporting a polybenzimidazole-membrane-based direct formate fuel cell (DFFC). Theoretically, the cell voltage of the high-temperature alkaline DFFC can be as high as 1.45 V at 90 °C. It has been demonstrated that a proof-of-concept alkaline DFFC without adding additional hydroxide yields a peak power density of 20.9 mW cm(-2) , an order of magnitude higher than both alkaline direct ethanol fuel cells and alkaline direct methanol fuel cells, mainly because the hydrolysis of formate provides enough OH(-) ions for formate oxidation reaction. It was also found that this hydroxide self-feeding high-temperature alkaline DFFC shows a stable 100 min constant-current discharge at 90 °C, proving the conceptual feasibility.

  3. Ion bombardment induced formation of micro-craters in plant cell envelopes

    NASA Astrophysics Data System (ADS)

    Sangyuenyongpipat, S.; Yu, L. D.; Vilaithong, T.; Brown, I. G.

    2006-01-01

    Ion beam bombardment of biological material has been recently applied for gene transfer in both plant and bacterial cells. A consistent physical mechanism for this significant result has not yet been developed. A fundamental question about the mechanism is the possible formation of pathways due to ion bombardment that are responsible for the gene transfer. We have carried out investigations of the effects of low-energy bombardment by both gaseous and metallic ion species of onion skin cells on their surface microstructure. Our experimental results reveal evidence demonstrating that the formation of micro-crater-like structures on the plant cell envelope surface is a general phenomenon consequent to ion bombardment, no matter what ion species, under certain ion beam conditions. The micro-craters are about 0.1-1 μm in size (diameter) and a few tens of nanometers in depth. The micro-crater formation process seems to be unrelated to the chemical composition of and rapid water evaporation from the cell envelope, but is associated with the special microstructure of the cell wall.

  4. Staufen1 impairs stress granule formation in skeletal muscle cells from myotonic dystrophy type 1 patients

    PubMed Central

    Ravel-Chapuis, Aymeric; Klein Gunnewiek, Amanda; Bélanger, Guy; Crawford Parks, Tara E.; Côté, Jocelyn; Jasmin, Bernard J.

    2016-01-01

    Myotonic dystrophy (DM1) is caused by an expansion of CUG repeats (CUGexp) in the DMPK mRNA 3′UTR. CUGexp-containing mRNAs become toxic to cells by misregulating RNA-binding proteins. Here we investigated the consequence of this RNA toxicity on the cellular stress response. We report that cell stress efficiently triggers formation of stress granules (SGs) in proliferating, quiescent, and differentiated muscle cells, as shown by the appearance of distinct cytoplasmic TIA-1– and DDX3-containing foci. We show that Staufen1 is also dynamically recruited into these granules. Moreover, we discovered that DM1 myoblasts fail to properly form SGs in response to arsenite. This blockage was not observed in DM1 fibroblasts, demonstrating a cell type–specific defect. DM1 myoblasts display increased expression and sequestration of toxic CUGexp mRNAs compared with fibroblasts. Of importance, down-regulation of Staufen1 in DM1 myoblasts rescues SG formation. Together our data show that Staufen1 participates in the inhibition of SG formation in DM1 myoblasts. These results reveal that DM1 muscle cells fail to properly respond to stress, thereby likely contributing to the complex pathogenesis of DM1. PMID:27030674

  5. Contribution of cell elongation to the biofilm formation of Pseudomonas aeruginosa during anaerobic respiration.

    PubMed

    Yoon, Mi Young; Lee, Kang-Mu; Park, Yongjin; Yoon, Sang Sun

    2011-01-18

    Pseudomonas aeruginosa, a gram-negative bacterium of clinical importance, forms more robust biofilm during anaerobic respiration, a mode of growth presumed to occur in abnormally thickened mucus layer lining the cystic fibrosis (CF) patient airway. However, molecular basis behind this anaerobiosis-triggered robust biofilm formation is not clearly defined yet. Here, we identified a morphological change naturally accompanied by anaerobic respiration in P. aeruginosa and investigated its effect on the biofilm formation in vitro. A standard laboratory strain, PAO1 was highly elongated during anaerobic respiration compared with bacteria grown aerobically. Microscopic analysis demonstrated that cell elongation likely occurred as a consequence of defective cell division. Cell elongation was dependent on the presence of nitrite reductase (NIR) that reduces nitrite (NO(2) (-)) to nitric oxide (NO) and was repressed in PAO1 in the presence of carboxy-PTIO, a NO antagonist, demonstrating that cell elongation involves a process to respond to NO, a spontaneous byproduct of the anaerobic respiration. Importantly, the non-elongated NIR-deficient mutant failed to form biofilm, while a mutant of nitrate reductase (NAR) and wild type PAO1, both of which were highly elongated, formed robust biofilm. Taken together, our data reveal a role of previously undescribed cell biological event in P. aeruginosa biofilm formation and suggest NIR as a key player involved in such process.

  6. Engineered Nanostructures of Haptens Lead to Unexpected Formation of Membrane Nanotubes Connecting Rat Basophilic Leukemia Cells

    SciTech Connect

    Li, Jie-Ren; Ross, Shailise S.; Liu, Yang; Liu, Ying X.; Wang, Kang-hsin; Chen, Huan-Yuan; Liu, Fu-Tong; Laurence, Ted A.; Liu, Gang-yu

    2015-06-09

    We report here on a recent finding that co-stimulation of the high-affinity immunoglobulin E (IgE) receptor (FcεRI) and the chemokine receptor 1 (CCR1) triggered formation of membrane nanotubes among bone-marrow-derived mast cells. The co-stimulation was attained using corresponding ligands: IgE binding antigen and macrophage inflammatory protein 1α (MIP1 α), respectively. However, this approach failed to trigger formation of nanotubes among rat basophilic leukemia (RBL) cells due to the lack of CCR1 on the cell surface (Int. Immunol. 2010, 22 (2), 113–128). RBL cells are frequently used as a model for mast cells and are best known for antibody-mediated activation via FcεRI. This work reports the successful formation of membrane nanotubes among RBLs using only one stimulus, a hapten of 2,4-dinitrophenyl (DNP) molecules, which are presented as nanostructures with our designed spatial arrangements. This observation underlines the significance of the local presentation of ligands in the context of impacting the cellular signaling cascades. In the case of RBL, certain DNP nanostructures suppress antigen-induced degranulation and facilitate the rearrangement of the cytoskeleton to form nanotubes. We conclude that these results demonstrate an important scientific concept; engineered nanostructures enable cellular signaling cascades, where current technologies encounter great difficulties. More importantly, nanotechnology offers a new platform to selectively activate and/or inhibit desired cellular signaling cascades.

  7. Engineered Nanostructures of Haptens Lead to Unexpected Formation of Membrane Nanotubes Connecting Rat Basophilic Leukemia Cells

    DOE PAGES

    Li, Jie-Ren; Ross, Shailise S.; Liu, Yang; ...

    2015-06-09

    We report here on a recent finding that co-stimulation of the high-affinity immunoglobulin E (IgE) receptor (FcεRI) and the chemokine receptor 1 (CCR1) triggered formation of membrane nanotubes among bone-marrow-derived mast cells. The co-stimulation was attained using corresponding ligands: IgE binding antigen and macrophage inflammatory protein 1α (MIP1 α), respectively. However, this approach failed to trigger formation of nanotubes among rat basophilic leukemia (RBL) cells due to the lack of CCR1 on the cell surface (Int. Immunol. 2010, 22 (2), 113–128). RBL cells are frequently used as a model for mast cells and are best known for antibody-mediated activation viamore » FcεRI. This work reports the successful formation of membrane nanotubes among RBLs using only one stimulus, a hapten of 2,4-dinitrophenyl (DNP) molecules, which are presented as nanostructures with our designed spatial arrangements. This observation underlines the significance of the local presentation of ligands in the context of impacting the cellular signaling cascades. In the case of RBL, certain DNP nanostructures suppress antigen-induced degranulation and facilitate the rearrangement of the cytoskeleton to form nanotubes. We conclude that these results demonstrate an important scientific concept; engineered nanostructures enable cellular signaling cascades, where current technologies encounter great difficulties. More importantly, nanotechnology offers a new platform to selectively activate and/or inhibit desired cellular signaling cascades.« less

  8. Expression of scavenger receptor‐AI promotes alternative activation of murine macrophages to limit hepatic inflammation and fibrosis

    PubMed Central

    Labonte, Adam C.; Sung, Sun‐Sang J.; Jennelle, Lucas T.; Dandekar, Aditya P.

    2016-01-01

    The liver maintains an immunologically tolerant environment as a result of continuous exposure to food and bacterial constituents from the digestive tract. Hepatotropic pathogens can take advantage of this niche and establish lifelong chronic infections causing hepatic fibrosis and hepatocellular carcinoma. Macrophages (Mϕ) play a critical role in regulation of immune responses to hepatic infection and regeneration of tissue. However, the factors crucial for Mϕ in limiting hepatic inflammation or resolving liver damage have not been fully understood. In this report, we demonstrate that expression of C‐type lectin receptor scavenger receptor‐AI (SR‐AI) is crucial for promoting M2‐like Mϕ activation and polarization during hepatic inflammation. Liver Mϕ uniquely up‐regulated SR‐AI during hepatotropic viral infection and displayed increased expression of alternative Mϕ activation markers, such as YM‐1, arginase‐1, and interleukin‐10 by activation of mer receptor tyrosine kinase associated with inhibition of mammalian target of rapamycin. Expression of these molecules was reduced on Mϕ obtained from livers of infected mice deficient for the gene encoding SR‐AI (msr1). Furthermore, in vitro studies using an SR‐AI‐deficient Mϕ cell line revealed impeded M2 polarization and decreased phagocytic capacity. Direct stimulation with virus was sufficient to activate M2 gene expression in the wild‐type (WT) cell line, but not in the knockdown cell line. Importantly, tissue damage and fibrosis were exacerbated in SR‐AI–/– mice following hepatic infection and adoptive transfer of WT bone‐marrow–derived Mϕ conferred protection against fibrosis in these mice. Conclusion: SR‐AI expression on liver Mϕ promotes recovery from infection‐induced tissue damage by mediating a switch to a proresolving Mϕ polarization state. (Hepatology 2017;65:32‐43). PMID:27770558

  9. Interplay between the dividing cell and its neighbors regulates adherens junction formation during cytokinesis in epithelial tissue.

    PubMed

    Herszterg, Sophie; Leibfried, Andrea; Bosveld, Floris; Martin, Charlotte; Bellaiche, Yohanns

    2013-02-11

    How adherens junctions (AJs) are formed upon cell division is largely unexplored. Here, we found that AJ formation is coordinated with cytokinesis and relies on an interplay between the dividing cell and its neighbors. During contraction of the cytokinetic ring, the neighboring cells locally accumulate Myosin II and produce the cortical tension necessary to set the initial geometry of the daughter cell interface. However, the neighboring cell membranes impede AJ formation. Upon midbody formation and concomitantly to neighboring cell withdrawal, Arp2/3-dependent actin polymerization oriented by the midbody maintains AJ geometry and regulates AJ final length and the epithelial cell arrangement upon division. We propose that cytokinesis in epithelia is a multicellular process, whereby the cooperative actions of the dividing cell and its neighbors define a two-tiered mechanism that spatially and temporally controls AJ formation while maintaining tissue cohesiveness.

  10. Integrin-Mediated Cell-Matrix Interaction in Physiological and Pathological Blood Vessel Formation

    PubMed Central

    Niland, Stephan; Eble, Johannes A.

    2012-01-01

    Physiological as well as pathological blood vessel formation are fundamentally dependent on cell-matrix interaction. Integrins, a family of major cell adhesion receptors, play a pivotal role in development, maintenance, and remodeling of the vasculature. Cell migration, invasion, and remodeling of the extracellular matrix (ECM) are integrin-regulated processes, and the expression of certain integrins also correlates with tumor progression. Recent advances in the understanding of how integrins are involved in the regulation of blood vessel formation and remodeling during tumor progression are highlighted. The increasing knowledge of integrin function at the molecular level, together with the growing repertoire of integrin inhibitors which allow their selective pharmacological manipulation, makes integrins suited as potential diagnostic markers and therapeutic targets. PMID:21941547

  11. Excess centrosomes perturb dynamic endothelial cell repolarization during blood vessel formation

    PubMed Central

    Kushner, Erich J.; Ferro, Luke S.; Yu, Zhixian; Bautch, Victoria L.

    2016-01-01

    Blood vessel formation requires dynamic movements of endothelial cells (ECs) within sprouts. The cytoskeleton regulates migratory polarity, and centrosomes organize the microtubule cytoskeleton. However, it is not well understood how excess centrosomes, commonly found in tumor stromal cells, affect microtubule dynamics and interphase cell polarity. Here we find that ECs dynamically repolarize during sprouting angiogenesis, and excess centrosomes block repolarization and reduce migration and sprouting. ECs with excess centrosomes initially had more centrosome-derived microtubules but, paradoxically, fewer steady-state microtubules. ECs with excess centrosomes had elevated Rac1 activity, and repolarization was rescued by blockade of Rac1 or actomyosin blockers, consistent with Rac1 activity promoting cortical retrograde actin flow and actomyosin contractility, which precludes cortical microtubule engagement necessary for dynamic repolarization. Thus normal centrosome numbers are required for dynamic repolarization and migration of sprouting ECs that contribute to blood vessel formation. PMID:27099371

  12. AI in the Elementary, Middle, and Secondary Classroom.

    ERIC Educational Resources Information Center

    Kirkpatrick, Susan N.; Biglan, Barbara

    1990-01-01

    Describes activities that present concepts and applications of artificial intelligence (AI) for elementary and secondary school students. The use of Logo with elementary students is discussed; appropriate software is described; programing activities using Logo, BASIC, and Prolog are examined; and the field of robotics is discussed. (four…

  13. AI in CALL--Artificially Inflated or Almost Imminent?

    ERIC Educational Resources Information Center

    Schulze, Mathias

    2008-01-01

    The application of techniques from artificial intelligence (AI) to CALL has commonly been referred to as intelligent CALL (ICALL). ICALL is only slightly older than the "CALICO Journal", and this paper looks back at a quarter century of published research mainly in North America and by North American scholars. This "inventory…

  14. New directions for Artificial Intelligence (AI) methods in optimum design

    NASA Technical Reports Server (NTRS)

    Hajela, Prabhat

    1989-01-01

    Developments and applications of artificial intelligence (AI) methods in the design of structural systems is reviewed. Principal shortcomings in the current approach are emphasized, and the need for some degree of formalism in the development environment for such design tools is underscored. Emphasis is placed on efforts to integrate algorithmic computations in expert systems.

  15. Artificial Intelligence: Is the Future Now for A.I.?

    ERIC Educational Resources Information Center

    Ramaswami, Rama

    2009-01-01

    In education, artificial intelligence (AI) has not made much headway. In the one area where it would seem poised to lend the most benefit--assessment--the reliance on standardized tests, intensified by the demands of the No Child Left Behind Act of 2001, which holds schools accountable for whether students pass statewide exams, precludes its use.…

  16. State Revolving Fund American Iron and Steel (AIS) Requirement

    EPA Pesticide Factsheets

    The AIS provision requires CWSRF and DWSRF assistance recipients to use iron and steel products that are produced in the U.S. It applies to projects for the construction, alteration, maintenance, or repair of a public water system or treatment work.

  17. Automatic Identification System (AIS) Transmit Testing in Louisville Phase 2

    DTIC Science & Technology

    2014-08-01

    project. Two of the captains were Capt. David Williams and Capt. Spencer Kennedy. After leaving SCI, the team members went to Crounse Inc. and met...team members had a phone conference with Herbert Taylor (VP Operations, Kongsberg Maritime Simulation Inc.) to discuss the integration of AIS data in

  18. 33 CFR 164.46 - Automatic Identification System (AIS).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... forth in IMO SN/Circ.227 (incorporated by reference, see § 164.03). Not all AIS units are able to broadcast position, course, and speed without the input of an external positioning device (e.g. dGPS); the use of other external devices (e.g. transmitting heading device, gyro, rate of turn indicator)...

  19. AI in Reverse: Computer Tools That Become Cognitive.

    ERIC Educational Resources Information Center

    Salomon, Gavriel

    The question of whether human thinking can come to simulate computer intelligence--i.e., AI in reverse--is addressed in this paper. Examples are given of three computer tools which perform several functions that constitute an intellectual partnership between student and tool. Such functions include: (1) assuming part of the intellectual burden in…

  20. AI/Simulation Fusion Project at Lawrence Livermore National Laboratory

    SciTech Connect

    Erickson, S.A.

    1984-04-25

    This presentation first discusses the motivation for the AI Simulation Fusion project. After discussing very briefly what expert systems are in general, what object oriented languages are in general, and some observed features of typical combat simulations, it discusses why putting together artificial intelligence and combat simulation makes sense. We then talk about the first demonstration goal for this fusion project.

  1. On the biomechanics of stem cell niche formation in the gut--modelling growing organoids.

    PubMed

    Buske, Peter; Przybilla, Jens; Loeffler, Markus; Sachs, Norman; Sato, Toshiro; Clevers, Hans; Galle, Joerg

    2012-09-01

    In vitro culture of intestinal tissue has been attempted for decades. Only recently did Sato et al. [Sato, T., Vries, R. G., Snippert, H. J., van de Wetering, M., Barker, N., Stange, D. E., van Es, J. H., Abo, A., Kujala, P., Peters, P. J., et al. (2009) Nature 459, 262-265] succeed in establishing long-term intestinal culture, demonstrating that cells expressing the Lgr5 gene can give rise to organoids with crypt-like domains similar to those found in vivo. In these cultures, Paneth cells provide essential signals supporting stem cell function. We have recently developed an individual cell-based computational model of the intestinal tissue [Buske, P., Galle, J., Barker, N., Aust, G., Clevers, H. & Loeffler, M. (2011) PLoS Comput Biol 7, e1001045]. The model is capable of quantitatively reproducing a comprehensive set of experimental data on intestinal cell organization. Here, we present a significant extension of this model that allows simulation of intestinal organoid formation in silico. For this purpose, we introduce a flexible basal membrane that assigns a bending modulus to the organoid surface. This membrane may be re-organized by cells attached to it depending on their differentiation status. Accordingly, the morphology of the epithelium is self-organized. We hypothesize that local tissue curvature is a key regulatory factor in stem cell organization in the intestinal tissue by controlling Paneth cell specification. In simulation studies, our model closely resembles the spatio-temporal organization of intestinal organoids. According to our results, proliferation-induced shape fluctuations are sufficient to induce crypt-like domains, and spontaneous tissue curvature induced by Paneth cells can control cell number ratios. Thus, stem cell expansion in an organoid depends sensitively on its biomechanics. We suggest a number of experiments that will enable new insights into mechano-transduction in the intestine, and suggest model extensions in the field of gland

  2. Chronic shear induces caveolae formation and alters ERK and Akt responses in endothelial cells

    NASA Technical Reports Server (NTRS)

    Boyd, Nolan L.; Park, Heonyong; Yi, Hong; Boo, Yong Chool; Sorescu, George P.; Sykes, Michelle; Jo, Hanjoong

    2003-01-01

    Caveolae are plasmalemmal domains enriched with cholesterol, caveolins, and signaling molecules. Endothelial cells in vivo are continuously exposed to shear conditions, and their caveolae density and location may be different from that of static cultured cells. Here, we show that chronic shear exposure regulates formation and localization of caveolae and caveolin-1 in bovine aortic endothelial cells (BAEC). Chronic exposure (1 or 3 days) of BAEC to laminar shear increased the total number of caveolae by 45-48% above static control. This increase was due to a rise in the luminal caveolae density without changing abluminal caveolae numbers or increasing caveolin-1 mRNA and protein levels. Whereas some caveolin-1 was found in the plasma membrane in static-cultured cells, it was predominantly localized in the Golgi. In contrast, chronic shear-exposed cells showed intense caveolin-1 staining in the luminal plasma membrane with minimum Golgi association. The preferential luminal localization of caveolae may play an important role in endothelial mechanosensing. Indeed, we found that chronic shear exposure (preconditioning) altered activation patterns of two well-known shear-sensitive signaling molecules (ERK and Akt) in response to a step increase in shear stress. ERK activation was blunted in shear preconditioned cells, whereas the Akt response was accelerated. These results suggest that chronic shear stimulates caveolae formation by translocating caveolin-1 from the Golgi to the luminal plasma membrane and alters cell signaling responses.

  3. Metformin Increases Mitochondrial Energy Formation in L6 Muscle Cell Cultures

    PubMed Central

    Vytla, Veeravenkata S.; Ochs, Raymond S.

    2013-01-01

    A popular hypothesis for the action of metformin, the widely used anti-diabetes drug, is the inhibition of mitochondrial respiration, specifically at complex I. This is consistent with metformin stimulation of glucose uptake by muscle and inhibition of gluconeogenesis by liver. Yet, mitochondrial inhibition is inconsistent with metformin stimulation of fatty acid oxidation in both tissues. In this study, we measured mitochondrial energy production in intact cells adapting an in vivo technique of phosphocreatine (PCr) formation following energy interruption (“PCr recovery”) to cell cultures. Metformin increased PCr recovery from either dinitrophenol (DNP) or azide in L6 cells. We found that metformin alone had no effect on cell viability as measured by total ATP concentration, trypan blue exclusion, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction. However, treatments with low concentrations of DNP or azide reversibly decreased ATP concentration. Metformin increased 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction during recovery from either agent. Viability measured by trypan blue exclusion indicated that cells were intact under these conditions. We also found that metformin increased free AMP and, to a smaller extent, free ADP concentrations in cells, an action that was duplicated by a structurally unrelated AMP deaminase inhibitor. We conclude that, in intact cells, metformin can lead to a stimulation of energy formation, rather than an inhibition. PMID:23720772

  4. Metformin increases mitochondrial energy formation in L6 muscle cell cultures.

    PubMed

    Vytla, Veeravenkata S; Ochs, Raymond S

    2013-07-12

    A popular hypothesis for the action of metformin, the widely used anti-diabetes drug, is the inhibition of mitochondrial respiration, specifically at complex I. This is consistent with metformin stimulation of glucose uptake by muscle and inhibition of gluconeogenesis by liver. Yet, mitochondrial inhibition is inconsistent with metformin stimulation of fatty acid oxidation in both tissues. In this study, we measured mitochondrial energy production in intact cells adapting an in vivo technique of phosphocreatine (PCr) formation following energy interruption ("PCr recovery") to cell cultures. Metformin increased PCr recovery from either dinitrophenol (DNP) or azide in L6 cells. We found that metformin alone had no effect on cell viability as measured by total ATP concentration, trypan blue exclusion, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction. However, treatments with low concentrations of DNP or azide reversibly decreased ATP concentration. Metformin increased 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction during recovery from either agent. Viability measured by trypan blue exclusion indicated that cells were intact under these conditions. We also found that metformin increased free AMP and, to a smaller extent, free ADP concentrations in cells, an action that was duplicated by a structurally unrelated AMP deaminase inhibitor. We conclude that, in intact cells, metformin can lead to a stimulation of energy formation, rather than an inhibition.

  5. Progressive mechanical indentation of large-format Li-ion cells

    NASA Astrophysics Data System (ADS)

    Wang, Hsin; Kumar, Abhishek; Simunovic, Srdjan; Allu, Srikanth; Kalnaus, Sergiy; Turner, John A.; Helmers, Jacob C.; Rules, Evan T.; Winchester, Clinton S.; Gorney, Philip

    2017-02-01

    Large format Li-ion cells were used to study the mechanical responses of single cells of thickness 6.5 mm and stacks of three cells under compressive loading. Various sequences of increasing depth indentations were carried out using a 1.0 inch (25.4 mm) diameter steel ball with steel plate as a rigid support surface. The indentation depths were between 0.025″ and 0.250″ with main indentation increments tests of 0.025″ steps. Increment steps of 0.100″ and 0.005″ were used to pinpoint the onset of internal-short that occurred between 0.245″ and 0.250″. The indented cells were disassembled and inspected for internal damage. Load vs. time curves were compared with the developed computer models. Separator thinning leading to the short circuit was simulated using both isotropic and anisotropic mechanical properties. Our study show that separators behave differently when tested as a single layer vs. a stack in a typical pouch cell. The collective responses of the multiple layers must be taken into account in failure analysis. A model that resolves the details of the individual internal cell components was able to simulate the internal deformation of the large format cells and the onset of failure assumed to coincide with the onset of internal short circuit.

  6. The formation of ordered nanoclusters controls cadherin anchoring to actin and cell–cell contact fluidity

    PubMed Central

    Strale, Pierre-Olivier; Duchesne, Laurence; Peyret, Grégoire; Montel, Lorraine; Nguyen, Thao; Png, Evelyn; Tampé, Robert; Troyanovsky, Sergey; Hénon, Sylvie; Ladoux, Benoit

    2015-01-01

    Oligomerization of cadherins could provide the stability to ensure tissue cohesion. Cadherins mediate cell–cell adhesion by forming trans-interactions. They form cis-interactions whose role could be essential to stabilize intercellular junctions by shifting cadherin clusters from a fluid to an ordered phase. However, no evidence has been provided so far for cadherin oligomerization in cellulo and for its impact on cell–cell contact stability. Visualizing single cadherins within cell membrane at a nanometric resolution, we show that E-cadherins arrange in ordered clusters, providing the first demonstration of the existence of oligomeric cadherins at cell–cell contacts. Studying the consequences of the disruption of the cis-interface, we show that it is not essential for adherens junction formation. Its disruption, however, increased the mobility of junctional E-cadherin. This destabilization strongly affected E-cadherin anchoring to actin and cell–cell rearrangement during collective cell migration, indicating that the formation of oligomeric clusters controls the anchoring of cadherin to actin and cell–cell contact fluidity. PMID:26195669

  7. Quantifying signaling-induced reorientation of T cell receptors during immunological synapse formation

    PubMed Central

    Moss, William C.; Irvine, Darrell J.; Davis, Mark M.; Krummel, Matthew F.

    2002-01-01

    Productive T cell recognition of antigen-presenting cells (APCs) is normally accompanied by the formation of a cell–cell contact called the “immunological synapse.” Our understanding of the steps leading up to this formation has been limited by the absence of tools for analyzing 3D surfaces and surface distributions as they change over time. Here we use a 3D fluorescence quantitation method to show that T cell receptors are recruited in bulk within the first minute after the onset of activation and with velocities ranging from 0.04 to 0.1 μm/s; a speed significantly greater than unrestricted diffusion. Our method reveals a second feature of this reorientation: a conformational change as the T cell pushes more total membrane into the interface creating a larger contact area for additional receptors. Analysis of individual T cell receptor velocities using a single-particle tracking method confirms our velocity measurement. This method should permit the quantitation of other dynamic membrane events and the associated movement of cell-surface molecules. PMID:12415110

  8. Absence of micronucleus formation in CHO-K1 cells cultivated in platelet lysate enriched medium.

    PubMed

    Bernardi, Martina; Adami, Valentina; Albiero, Elena; Madeo, Domenico; Rodeghiero, Francesco; Astori, Giuseppe

    2014-03-01

    Human platelet lysate (PL) represents an effective substitute of fetal bovine serum (FBS) for mesenchymal stromal cell (MSC) cultivation. Compared to FBS, PL favors MSC proliferation significantly shortening the population doubling time and avoiding the risks related to the use of animal derivatives. Growth factors contained in the platelets are released upon platelet disruption following freezing/thawing cycles or as we have recently described by using ultrasound. We have investigated whether the increased cell proliferation achieved by using PL could induce mitotic stress and whether the potential formation of free radicals during PL production by ultrasound could cause chromosomal instability in mammalian cells. We have applied an image analysis assisted high content screening (HCS) in vitro micronucleus assay in the Chinese Hamster Ovarian K1 (CHO-K1) rodent mammalian cell line. PL was produced by sonication; for the micronucleus assay, CHO-K1 cells were exposed to increasing concentrations of PL. Cytokinesis was blocked by cytochalasin B, nuclei were stained with bisbenzimide and images were acquired and analyzed automatically using an HCS system, both with a 20× and a 10× objective. Our results suggest that growth stimulus induced by the use of PL did not significantly increase micronucleus formation in CHO-K1 cells compared to negative control. Micronucleus testing in conjunction with HCS could represent a valid tool to evaluate the safety of ancillary materials used in the production of cell-based medicinal products.

  9. Meiotic germ cells antagonize mesonephric cell migration and testis cord formation in mouse gonads

    PubMed Central

    Yao, Humphrey H.-C.; DiNapoli, Leo; Capel, Blanche

    2014-01-01

    Summary The developmental fate of primordial germ cells in the mammalian gonad depends on their environment. In the XY gonad, Sry induces a cascade of molecular and cellular events leading to the organization of testis cords. Germ cells are sequestered inside testis cords by 12.5 dpc where they arrest in mitosis. If the testis pathway is not initiated, germ cells spontaneously enter meiosis by 13.5 dpc, and the gonad follows the ovarian fate. We have previously shown that some testis-specific events, such as mesonephric cell migration, can be experimentally induced into XX gonads prior to 12.5 dpc. However, after that time, XX gonads are resistant to the induction of cell migration. In current experiments, we provide evidence that this effect is dependent on XX germ cells rather than on XX somatic cells. We show that, although mesonephric cell migration cannot be induced into normal XX gonads at 14.5 dpc, it can be induced into XX gonads depleted of germ cells. We also show that when 14.5 dpc XX somatic cells are recombined with XY somatic cells, testis cord structures form normally; however, when XX germ cells are recombined with XY somatic cells, cord structures are disrupted. Sandwich culture experiments suggest that the inhibitory effect of XX germ cells is mediated through short-range interactions rather than through a long-range diffusible factor. The developmental stage at which XX germ cells show a disruptive effect on the male pathway is the stage at which meiosis is normally initiated, based on the immunodetection of meiotic markers. We suggest that at the stage when germ cells commit to meiosis, they reinforce ovarian fate by antagonizing the testis pathway. PMID:14561636

  10. PPARγ negatively regulates T cell activation to prevent follicular helper T cells and germinal center formation.

    PubMed

    Park, Hong-Jai; Kim, Do-Hyun; Choi, Jin-Young; Kim, Won-Ju; Kim, Ji Yun; Senejani, Alireza G; Hwang, Soo Seok; Kim, Lark Kyun; Tobiasova, Zuzana; Lee, Gap Ryol; Craft, Joseph; Bothwell, Alfred L M; Choi, Je-Min

    2014-01-01

    Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor that regulates lipid and glucose metabolism. Although studies of PPARγ ligands have demonstrated its regulatory functions in inflammation and adaptive immunity, its intrinsic role in T cells and autoimmunity has yet to be fully elucidated. Here we used CD4-PPARγKO mice to investigate PPARγ-deficient T cells, which were hyper-reactive to produce higher levels of cytokines and exhibited greater proliferation than wild type T cells with increased ERK and AKT phosphorylation. Diminished expression of IκBα, Sirt1, and Foxo1, which are inhibitors of NF-κB, was observed in PPARγ-deficient T cells that were prone to produce all the signature cytokines under Th1, Th2, Th17, and Th9 skewing condition. Interestingly, 1-year-old CD4-PPARγKO mice spontaneously developed moderate autoimmune phenotype by increased activated T cells, follicular helper T cells (TFH cells) and germinal center B cells with glomerular inflammation and enhanced autoantibody production. Sheep red blood cell immunization more induced TFH cells and germinal centers in CD4-PPARγKO mice and the T cells showed increased of Bcl-6 and IL-21 expression suggesting its regulatory role in germinal center reaction. Collectively, these results suggest that PPARγ has a regulatory role for TFH cells and germinal center reaction to prevent autoimmunity.

  11. Trypanosoma cruzi: Entry into Mammalian Host Cells and Parasitophorous Vacuole Formation

    PubMed Central

    Barrias, Emile Santos; de Carvalho, Tecia Maria Ulisses; De Souza, Wanderley

    2013-01-01

    Trypanosoma cruzi, the causative agent of Chagas disease, is transmitted to vertebrate hosts by blood-sucking insects. This protozoan is an obligate intracellular parasite. The infective forms of the parasite are the metacyclic trypomastigotes, amastigotes, and bloodstream trypomastigotes. The recognition between the parasite and mammalian host cell, involves numerous molecules present in both cell types, and similar to several intracellular pathogens, T. cruzi is internalized by host cells via multiple endocytic pathways. Morphological studies demonstrated that after the interaction of the infective forms of T. cruzi with phagocytic or non-phagocytic cell types, plasma membrane (PM) protrusions can form, showing similarity with those observed during canonical phagocytosis or macropinocytic events. Additionally, several molecules known to be molecular markers of membrane rafts, macropinocytosis, and phagocytosis have been demonstrated to be present at the invasion site. These events may or may not depend on the host cell lysosomes and cytoskeleton. In addition, after penetration, components of the host endosomal-lysosomal system, such as early endosomes, late endosomes, and lysosomes, participate in the formation of the nascent parasitophorous vacuole (PV). Dynamin, a molecule involved in vesicle formation, has been shown to be involved in the PV release from the host cell PM. This review focuses on the multiple pathways that T. cruzi can use to enter the host cells until complete PV formation. We will describe different endocytic processes, such as phagocytosis, macropinocytosis, and endocytosis using membrane microdomains and clathrin-dependent endocytosis and show results that are consistent with their use by this smart parasite. We will also discuss others mechanisms that have been described, such as active penetration and the process that takes advantage of cell membrane wound repair. PMID:23914186

  12. Mic13 Is Essential for Formation of Crista Junctions in Mammalian Cells.

    PubMed

    Anand, Ruchika; Strecker, Valentina; Urbach, Jennifer; Wittig, Ilka; Reichert, Andreas S

    2016-01-01

    Mitochondrial cristae are connected to the inner boundary membrane via crista junctions which are implicated in the regulation of oxidative phosphorylation, apoptosis, and import of lipids and proteins. The MICOS complex determines formation of crista junctions. We performed complexome profiling and identified Mic13, also termed Qil1, as a subunit of the MICOS complex. We show that MIC13 is an inner membrane protein physically interacting with MIC60, a central subunit of the MICOS complex. Using the CRISPR/Cas method we generated the first cell line deleted for MIC13. These knockout cells show a complete loss of crista junctions demonstrating that MIC13 is strictly required for the formation of crista junctions. MIC13 is required for the assembly of MIC10, MIC26, and MIC27 into the MICOS complex. However, it is not needed for the formation of the MIC60/MIC19/MIC25 subcomplex suggesting that the latter is not sufficient for crista junction formation. MIC13 is also dispensable for assembly of respiratory chain complexes and for maintaining mitochondrial network morphology. Still, lack of MIC13 resulted in a moderate reduction of mitochondrial respiration. In summary, we show that MIC13 has a fundamental role in crista junction formation and that assembly of respiratory chain supercomplexes is independent of mitochondrial cristae shape.

  13. Mic13 Is Essential for Formation of Crista Junctions in Mammalian Cells

    PubMed Central

    Anand, Ruchika; Strecker, Valentina; Urbach, Jennifer; Wittig, Ilka; Reichert, Andreas S.

    2016-01-01

    Mitochondrial cristae are connected to the inner boundary membrane via crista junctions which are implicated in the regulation of oxidative phosphorylation, apoptosis, and import of lipids and proteins. The MICOS complex determines formation of crista junctions. We performed complexome profiling and identified Mic13, also termed Qil1, as a subunit of the MICOS complex. We show that MIC13 is an inner membrane protein physically interacting with MIC60, a central subunit of the MICOS complex. Using the CRISPR/Cas method we generated the first cell line deleted for MIC13. These knockout cells show a complete loss of crista junctions demonstrating that MIC13 is strictly required for the formation of crista junctions. MIC13 is required for the assembly of MIC10, MIC26, and MIC27 into the MICOS complex. However, it is not needed for the formation of the MIC60/MIC19/MIC25 subcomplex suggesting that the latter is not sufficient for crista junction formation. MIC13 is also dispensable for assembly of respiratory chain complexes and for maintaining mitochondrial network morphology. Still, lack of MIC13 resulted in a moderate reduction of mitochondrial respiration. In summary, we show that MIC13 has a fundamental role in crista junction formation and that assembly of respiratory chain supercomplexes is independent of mitochondrial cristae shape. PMID:27479602

  14. Somite-Derived Retinoic Acid Regulates Zebrafish Hematopoietic Stem Cell Formation

    PubMed Central

    Pillay, Laura M.; Mackowetzky, Kacey J.; Widen, Sonya A.; Waskiewicz, Andrew Jan

    2016-01-01

    Hematopoietic stem cells (HSCs) are multipotent progenitors that generate all vertebrate adult blood lineages. Recent analyses have highlighted the importance of somite-derived signaling factors in regulating HSC specification and emergence from dorsal aorta hemogenic endothelium. However, these factors remain largely uncharacterized. We provide evidence that the vitamin A derivative retinoic acid (RA) functions as an essential regulator of zebrafish HSC formation. Temporal analyses indicate that RA is required for HSC gene expression prior to dorsal aorta formation, at a time when the predominant RA synthesis enzyme, aldh1a2, is strongly expressed within the paraxial mesoderm and somites. Previous research implicated the Cxcl12 chemokine and Notch signaling pathways in HSC formation. Consequently, to understand how RA regulates HSC gene expression, we surveyed the expression of components of these pathways in RA-depleted zebrafish embryos. During somitogenesis, RA-depleted embryos exhibit altered expression of jam1a and jam2a, which potentiate Notch signaling within nascent endothelial cells. RA-depleted embryos also exhibit a severe reduction in the expression of cxcr4a, the predominant Cxcl12b receptor. Furthermore, pharmacological inhibitors of RA synthesis and Cxcr4 signaling act in concert to reduce HSC formation. Our analyses demonstrate that somite-derived RA functions to regulate components of the Notch and Cxcl12 chemokine signaling pathways during HSC formation. PMID:27861498

  15. Regulation of product formation during glucose or lactose limitation in nongrowing cells of Streptococcus lactis.

    PubMed

    Fordyce, A M; Crow, V L; Thomas, T D

    1984-08-01

    Nongrowing cells of Streptococcus lactis in a pH-stat were dosed with sugar to allow fermentation at the maximum rate or were fed a continuous supply of sugar at rates less than the maximum. Under anaerobic conditions, rapid fermentation of either glucose or lactose was essentially homolactic. However, with strain ML3, limiting the fermentation rate diverted approximately half of the pyruvate to formate, acetate, and ethanol. At limiting glucose fermentation rates, cells contained lower concentrations of lactate dehydrogenase activator (fructose 1,6-diphosphate) and pyruvate formate-lyase inhibitors (triose phosphates). As a result, pyruvate formate-lyase and pyruvate dehydrogenase play a greater role in pyruvate metabolism. In contrast to strain ML3, strain ML8 did not give the same diversion of products under anaerobic conditions, and cells retained higher concentrations of the above effector compounds. Lactose metabolism under aerobic conditions resulted in pyruvate excretion by both S. lactis ML3 and ML8. At 7% of the maximum utilization rate, pyruvate accounted for 69 and 35% of the lactose metabolized by ML3 and ML8, respectively. Acetate was also a major product, especially with ML8. The data suggest that NADH oxidase is involved in coenzyme recycling in the presence of oxygen and that pyruvate formate-lyase is inactivated, but the pyruvate dehydrogenase complex still functions.

  16. Ice formation in PEM fuel cells operated isothermally at sub-freezing temperatures

    SciTech Connect

    Mukundan, Rangachary; Luhan, Roger W; Davey, John R; Spendelow, Jacob S; Borup, Rodney L; Hussey, Daniel S; Jacobson, David L; Arif, Muhammad

    2009-01-01

    The effect of MEA and GDL structure and composition on the performance of single-PEM fuel cells operated isothermally at subfreezing temperatures is presented. The cell performance and durability are not only dependent on the MEA/GDL materials used but also on their interfaces. When a cell is operated isothermally at sub-freezing temperatures in constant current mode, the water formation due to the current density initially hydrates the membrane/ionomer and then forms ice in the catalyst layer/GDL. An increase in high frequency resistance was also observed in certain MEAs where there is a possibility of ice formation between the catalyst layer and GDL leading to a loss in contact area. The total water/ice holding capacity for any MEA was lower at lower temperatures and higher current densities. The durability of MEAs subjected to multiple isothermal starts was better for LANL prepared MEAs as compared to commercial MEAs, and cloth GDLs when compared to paper GDLs. The ice formation was monitored using high-resolution neutron radiography and was found to be concentrated near the cathode catalyst layer. However, there was significant ice formation in the GDLs especially at the higher temperature ({approx} -10 C) and lower current density (0.02 A/cm{sup 2}) operations. These results are consistent with the longer-term durability observations that show more severe degradation at the lower temperatures.

  17. Human muscle precursor cells overexpressing PGC-1α enhance early skeletal muscle tissue formation.

    PubMed

    Haralampieva, Deana; Salemi, Souzan; Dinulovic, Ivana; Sulser, Tullio; M Ametamey, Simon; Handschin, Christoph; Eberli, Daniel

    2017-02-03

    Muscle precursor cells (MPCs) are activated satellite cells capable of muscle fiber reconstruction. Therefore, autologous MPC transplantation is envisioned for the treatment of muscle diseases. However, the density of MPCs, as well as their proliferation and differentiation potential gradually decline with age. The goal of this research was to genetically modify human MPCs (hMPCs) to overexpress the peroxisome proliferator-activated receptor gamma coactivator (PGC-1α), a key regulator of exercise-mediated adaptation, and thereby to enhance early skeletal muscle formation and quality. We were able to confirm the sustained myogenic phenotype of the genetically modified hMPCs. While maintaining their viability and proliferation potential, PGC-1α modified hMPCs showed an enhanced myofiber formation capacity in vitro. Engineered muscle tissues were harvested 1, 2 and 4 weeks after subcutaneous injection of cell-collagen suspensions and histological analysis confirmed the earlier myotube formation in PGC-1α modified samples, predominantly of slow twitch myofibers. Increased contractile protein levels were detected by Western Blot. In summary, by genetically modifying hMPCs to overexpress PGC-1α we were able to promote early muscle fiber formation in vitro and in vivo, with an initial switch to slow type myofibers. Therefore, overexpressing PGC-1α is novel strategy to further enhance skeletal muscle tissue engineering.

  18. Synapse formation between clonal neuroblastoma X glioma hybrid cells and striated muscle cells.

    PubMed Central

    Nelson, P; Christian, C; Nirenberg, M

    1976-01-01

    Clonal neuroblastoma X glioma hybrid cells were shown to form synapses with cultured, striated muscle cells. The properties of the synapses between hybrid and muscle cells were similar to those of the normal, neuromuscular synapse at an early stage of development. The number of synapses formed and the efficiency of transmission across synapses were found to be regulated, apparently independently, by components in the culture medium. Under appropriate conditions synapses were found with 20% of the hybrid-muscle cell pairs examined; thus, the hybrid cells form synapses with relatively high frequency. Images PMID:1061105

  19. Vitrified canine testicular cells allow the formation of spermatogonial stem cells and seminiferous tubules following their xenotransplantation into nude mice

    PubMed Central

    Lee, Kyung Hoon; Lee, Won Young; Kim, Dong Hoon; Lee, Seung Hoon; Do, Jung Tae; Park, Chankyu; Kim, Jae Hwan; Choi, Young Suk; Song, Hyuk

    2016-01-01

    Belgian Malinois (BM), one of the excellent military dog breeds in South Korea, is usually castrated before sexual maturation. Therefore, the transfer of their genetic features to the next generation is difficult. To overcome this, testicular cells from 4-month-old BMs were frozen. Testicular cells were thawed after 3 months and cultured in StemPro-34 medium. Spermatogonial stem cell (SSC) characteristics were determined by the transplantation of the cultured germ cell-derived colonies (GDCs) into empty testes, containing only several endogenous SSCs and Sertoli cells, of immunodeficient mice, 4 weeks after busulfan treatment. Following the implantation, the transplanted cells localized in the basement membrane of the seminiferous tubules, and ultimately colonized the recipient testes. Xenotransplantation of GDCs together with testicular somatic cells conjugated with extracellular matrix (ECM), led to the formation of de novo seminiferous tubules. These seminiferous tubules were mostly composed of Sertoli cells. Some germ cells were localized in the basement membrane of seminiferous tubules. This study revealed that BM-derived SSCs, obtained from the castrated testes, might be a valuable tool for the transfer of BM genetic features to the next generation. PMID:26907750

  20. Laser annealing of ion implanted CZ silicon for solar cell junction formation

    NASA Technical Reports Server (NTRS)

    Katzeff, J. S.

    1981-01-01

    The merits of large spot size pulsed laser annealing of phosphorus implanted, Czochralski grown silicon for function formation of solar cells are evaluated. The feasibility and requirements are also determined to scale-up a laser system to anneal 7.62 cm diameter wafers at a rate of one wafer/second. Results show that laser annealing yields active, defect-free, shallow junction devices. Functional cells with AM 1 conversion efficiencies up to 15.4% for 2 x 2 cm and 2 x 4 cm sizes were attained. For larger cells, 7.62 cm dia., conversion efficiencies ranged up to 14.5%. Experiments showed that texture etched surfaces are not compatible with pulsed laser annealing due to the surface melting caused by the laser energy. When compared with furnace annealed cells, the laser annealed cells generally exhibited conversion efficiencies which were equal to or better than those furnace annealed. In addition, laser annealing has greater throughput potential.

  1. Macrophage metalloproteinases degrade high-density-lipoprotein-associated apolipoprotein A-I at both the N- and C-termini.

    PubMed Central

    Eberini, Ivano; Calabresi, Laura; Wait, Robin; Tedeschi, Gabriella; Pirillo, Angela; Puglisi, Lina; Sirtori, Cesare R; Gianazza, Elisabetta

    2002-01-01

    Atheromatous plaques contain various cell types, including macrophages, endothelial cells and smooth-muscle cells. To investigate the possible interactions between secreted matrix metalloproteinases and high-density lipoprotein (HDL) components, we tested the above cell types by culturing them for 24 h. HDL(3) (HDL subfractions with average sizes of between 8.44 nm for HDL(3A) and 7.62 nm for HDL(3C)) were then incubated in their cell-free conditioned media. Proteolytic degradation of apolipoprotein A-I was observed with macrophages, but not with endothelial-cell- or muscle-cell-conditioned supernatant. Absence of calcium or addition of EDTA to incubation media prevented all proteolytic processes. The identified apolipoprotein A-I fragments had sizes of 26, 22, 14 and 9 kDa. Two-dimensional electrophoresis and MS resolved the 26 and the 22 kDa components and identified peptides resulting from both N- and C-terminal cleavage of apolipoprotein A-I. The higher abundance of C- than N-terminally cleaved peptides agrees with data in the literature for a fully structured alpha-helix around Tyr(18) compared with an unstructured region around Gly(185) and Gly(186). The flexibility in the latter region of apolipoprotein A-I may explain its susceptibility to proteolysis. In our experimental set-up, HDL(3C) was more extensively degraded than the other HDL(3) subclasses (HDL(3A) and HDL(3B)). Proteolytic fragments produced by metalloproteinase action were shown by gel filtration and electrophoresis to be neither associated with lipids nor self-associated. PMID:11879189

  2. Enhanced mitochondrial superoxide in hyperglycemic endothelial cells: direct measurements and formation of hydrogen peroxide and peroxynitrite.

    PubMed

    Quijano, Celia; Castro, Laura; Peluffo, Gonzalo; Valez, Valeria; Radi, Rafael

    2007-12-01

    Hyperglycemic challenge to bovine aortic endothelial cells (BAECs) increases oxidant formation and cell damage that are abolished by MnSOD overexpression, implying mitochondrial superoxide (O(2)(.-)) as a central mediator. However, mitochondrial O(2)(.-) and its steady-state concentrations have not been measured directly yet. Therefore, we aimed to detect and quantify O(2)(.-) through different techniques, along with the oxidants derived from it. Mitochondrial aconitase, a sensitive target of O(2)(.-), was inactivated 60% in BAECs incubated in 30 mM glucose (hyperglycemic condition) with respect to cells incubated in 5 mM glucose (normoglycemic condition). Under hyperglycemic conditions, increased oxidation of the mitochondrially targeted hydroethidine derivative (MitoSOX) to hydroxyethidium, the product of the reaction with O(2)(.-), could be specifically detected. An 8.8-fold increase in mitochondrial O(2)(.-) steady-state concentration (to 250 pM) and formation rate (to 6 microM/s) was estimated. Superoxide formation increased the intracellular concentration of both hydrogen peroxide, measured as 3-amino-2,4,5-triazole-mediated inactivation of catalase, and nitric oxide-derived oxidants (i.e., peroxynitrite), evidenced by immunochemical detection of 3-nitrotyrosine. Oxidant formation was further evaluated by chloromethyl dichlorodihydrofluorescein (CM-H(2)DCF) oxidation. Exposure to hyperglycemic conditions triggered the oxidation of CM-H(2)DCF and was significantly reduced by pharmacological agents that lower the mitochondrial membrane potential, inhibit electron transport (i.e., myxothiazol), and scavenge mitochondrial oxidants (i.e., MitoQ). In BAECs devoid of mitochondria (rho(0) cells), hyperglycemic conditions did not increase CM-H(2)DCF oxidation. Mitochondrial O(2)(.-) formation in hyperglycemic conditions was associated with increased glucose metabolization in the Krebs cycle and hyperpolarization of the mitochondrial membrane.

  3. Dissecting the molecular mechanisms that impair stress granule formation in aging cells.

    PubMed

    Moujaber, Ossama; Mahboubi, Hicham; Kodiha, Mohamed; Bouttier, Manuella; Bednarz, Klaudia; Bakshi, Ragini; White, John; Larose, Louise; Colmegna, Inés; Stochaj, Ursula

    2017-03-01

    Aging affects numerous aspects of cell biology, but the senescence-associated changes in the stress response are only beginning to emerge. To obtain mechanistic insights into these events, we examined the formation of canonical and non-canonical stress granules (SGs) in the cytoplasm. SG generation is a key event after exposure to physiological or environmental stressors. It requires the SG-nucleating proteins G3BP1 and TIA-1/TIAR and stress-related signaling events. To analyze SG formation, we used two independent models of somatic cell aging. In both model systems, cellular senescence impaired the assembly of two SG classes: (i) it compromised the formation of canonical SGs, and (ii) skewed the production of non-canonical SGs. We dissected the mechanisms underlying these senescence-dependent changes in granule biogenesis and identified several specific targets that were modulated by aging. Thus, we demonstrate a depletion of G3BP1 and TIA-1/TIAR in senescent cells and show that the loss of G3BP1 contributed to impaired SG formation. We further reveal that aging reduced Sp1 levels; this transcription factor regulated G3BP1 and TIA-1/TIAR abundance. The assembly of canonical SGs relies on the phosphorylation of translation initiation factor eIF2α. We show that senescence can cause eIF2α hyperphosphorylation. CReP is a subunit of protein phosphatase 1 and critical to reverse the stress-dependent phosphorylation of eIF2α. We demonstrate that the loss of CReP correlated with the aging-related hyperphosphorylation of eIF2α. Together, we have identified significant changes in the stress response of aging cells and provide mechanistic insights. Based on our work, we propose that the decline in SG formation can provide a new biomarker to evaluate cellular aging.

  4. Effect of molecular composition of heparin and cellulose sulfate on multilayer formation and cell response.

    PubMed

    Aggarwal, Neha; Altgärde, Noomi; Svedhem, Sofia; Zhang, Kai; Fischer, Steffen; Groth, Thomas

    2013-11-12

    Here, the layer-by-layer method was applied to assemble films from chitosan paired with either heparin or a semisynthetic cellulose sulfate (CS) that possessed a higher sulfation degree than heparin. Ion pairing was exploited during multilayer formation at pH 4, while hydrogen bonding is likely to occur at pH 9. Effects of polyanions and pH value during layer formation on multilayers properties were studied by surface plasmon resonance ("dry layer mass"), quartz crystal microbalance with dissipation monitoring ("wet layer mass"), water contact angle, and zeta potential measurements. Bioactivity of multilayers was studied regarding fibronectin adsorption and adhesion/proliferation of C2C12 myoblast cells. Layer growth and dry mass were higher for both polyanions at pH 4 when ion pairing occurred, while it decreased significantly with heparin at pH 9. By contrast, CS as polyanion resulted also in high layer growth and mass at pH 9, indicating a much stronger effect of hydrogen bonding between chitosan and CS. Water contact angle and zeta potential measurements indicated a more separated structure of multilayers from chitosan and heparin at pH 4, while CS led to a more fuzzy intermingled structure at both pH values. Cell behavior was highly dependent on pH during multilayer formation with heparin as polyanion and was closely related to fibronectin adsorption. By contrast, CS and chitosan did not show such dependency on pH value, where adhesion and growth of cells was high. Results of this study show that CS is an attractive candidate for multilayer formation that does not depend so strongly on pH during multilayer formation. In addition, such multilayer system also represents a good substrate for cell interactions despite the rather soft structure. As previous studies have shown specific interaction of CS with growth factors, multilayers from chitosan and CS may be of great interest for different biomedical applications.

  5. Assays to examine endothelial cell migration, tube formation, and gene expression profiles.

    PubMed

    Guo, Shuzhen; Lok, Josephine; Liu, Yi; Hayakawa, Kazuhide; Leung, Wendy; Xing, Changhong; Ji, Xunming; Lo, Eng H

    2014-01-01

    Common methods for studying angiogenesis in vitro include the tube formation assay, the migration assay, and the study of the endothelial genome. The formation of capillary-like tubes in vitro on basement membrane matrix mimics many steps of the angiogenesis process in vivo and is used widely as a screening test for angiogenic or antiangiogenic factors. Other assays related to the study of angiogenesis include the cell migration assay, the study of gene expression changes during the process of angiogenesis, and the study of endothelial-derived microparticles. Protocols for these procedures will be described here.

  6. Fuels for fuel cells: Fuel and catalyst effects on carbon formation

    SciTech Connect

    Borup, R. L.; Inbody, M. A.; Perry, W. L.; Parkinson, W. J. ,

    2002-01-01

    The goal of this research is to explore the effects of fuels, fuel constituents, additives and impurities on the performance of on-board hydrogen generation devices and consequently on the overall performance of fuel cell systems using reformed hydrocarbon fuels. Different fuels and components have been tested in automotive scale, adiabatic autothermal reactors to observe their relative reforming characteristics with various operating conditions. Carbon formation has been modeled and was experimentally monitored in situ during operation by laser measurements of the effluent reformate. Ammonia formation was monitored, and conditions varied to observe under what conditions N H 3 is made.

  7. Cell lineage, axis formation, and the origin of germ layers in the amphipod crustacean Orchestia cavimana.

    PubMed

    Wolff, Carsten; Scholtz, Gerhard

    2002-10-01

    Embryos of the amphipod crustacean Orchestia cavimana are examined during cleavage, gastrulation, and segmentation by using in vivo labelling. Single blastomeres of the 8- and 16-cell stages were labelled with DiI to trace cell lineages. Early cleavage follows a distinct pattern and the a/p and d/v body axes are already determined at the 4- and 8-cell stages, respectively. In these stages, the germinal rudiment and the naupliar mesoderm can be traced back to a single blastomere each. In addition, the ectoderm and the postnaupliar mesoderm are separated into right and left components. At the16-cell stage, naupliar ectoderm is divided from the postnaupliar ectoderm, and extraembryonic lineages are separated from postnaupliar mesoderm and endoderm. From our investigation, it is evident that the cleavage pattern and cell lineage of Orchestia cavimana are not of the spiral type. Furthermore, the results of the labelling show many differences to cleavage patterns and cell lineages in other crustaceans, in particular, other Malacostraca. The cleavage and cell lineage patterns of the amphipod Orchestia are certainly derived within Malacostraca, whose ancestral cleavage mode was most likely of the superficial type. On the other hand, Orchestia exhibits a stereotyped cell division pattern during formation and differentiation of the germ band that is typical for malacostracans. Hence, a derived (apomorphic) early cleavage pattern is the ontogenetic basis for an evolutionarily older cell division pattern of advanced developmental stages. O. cavimana offers the possibility to trace the lineages and the fates of cells from early developmental stages up to the formation of segmental structures, including neurogenesis at a level of resolution that is not matched by any other arthropod system.

  8. Engineering Strategies for the Formation of Embryoid Bodies from Human Pluripotent Stem Cells

    PubMed Central

    Pettinato, Giuseppe

    2015-01-01

    Human pluripotent stem cells (hPSCs) are powerful tools for regenerative therapy and studying human developmental biology, attributing to their ability to differentiate into many functional cell types in the body. The main challenge in realizing hPSC potential is to guide their differentiation in a well-controlled manner. One way to control the cell differentiation process is to recapitulate during in vitro culture the key events in embryogenesis to obtain the three developmental germ layers from which all cell types arise. To achieve this goal, many techniques have been tested to obtain a cellular cluster, an embryoid body (EB), from both mouse and hPSCs. Generation of EBs that are homogeneous in size and shape would allow directed hPSC differentiation into desired cell types in a more synchronous manner and define the roles of cell–cell interaction and spatial organization in lineage specification in a setting similar to in vivo embryonic development. However, previous success in uniform EB formation from mouse PSCs cannot be extrapolated to hPSCs possibly due to the destabilization of adherens junctions on cell surfaces during the dissociation into single cells, making hPSCs extremely vulnerable to cell death. Recently, new advances have emerged to form uniform human embryoid bodies (hEBs) from dissociated single cells of hPSCs. In this review, the existing methods for hEB production from hPSCs and the results on the downstream differentiation of the hEBs are described with emphases on the efficiency, homogeneity, scalability, and reproducibility of the hEB formation process and the yield in terminal differentiation. New trends in hEB production and directed differentiation are discussed. PMID:25900308

  9. Regional development of Langerhans cells and formation of Birbeck granules in human embryonic and fetal skin.

    PubMed

    Fujita, M; Furukawa, F; Horiguchi, Y; Ueda, M; Kashihara-Sawami, M; Imamura, S

    1991-07-01

    The regional development of Langerhans cells (LC) and the formation of Birbeck granules (BG) were examined in human embryonic and fetal skin. Samples were obtained from multiple anatomic sites and stained with anti-CD36, anti-CD1a, and anti-HLA-DR antibody as well as Lag antibody specifically reactive to BG and some vacuoles of human LC. In the first trimester, CD36+ dendritic epidermal cells were identified before the appearance of CD1a+ cells and Lag+ cells. Some of the former co-expressed HLA-DR antigens but not CD1a antigens. In the second trimester, regional variations in LC development were observed. Epidermal LC of palms and soles reached a peak in number in the first trimester but were rarely detected after 18 weeks estimated gestation age (EGA), whereas, in other regions, their number increased with age. In the second trimester, CD1a+ cells and Lag+ cells were also identified in the epidermis, although Lag+ cells appeared later than CD1a+ cells. The Lag+ cells until 17 weeks EGA showed a variety of staining intensities and immunoelectron microscopy revealed that they contained various amounts of Lag-reactive BG. Flow cytometric analysis showed that relative amounts of Lag antigens in LC increased during the second trimester and that fetal LC of 18 weeks EGA expressed the same amounts of HLA-DR, CD1a, and Lag antigens as did adult human LC. In the dermis, in the second trimester, numerous CD36+ cells and HLA-DR+ cells were found, whereas CD1a+ cells and Lag+ cells were rarely detected. Taken together, it is suggested that HLA-DR+ dendritic cells acquire CD1a+ antigens first and then form BG after migration to the epidermis and that fetal LC are phenotypically mature in the second trimester.

  10. Cell surface attachment structures contribute to biofilm formation and xylem colonization by Erwinia amylovora.

    PubMed

    Koczan, Jessica M; Lenneman, Bryan R; McGrath, Molly J; Sundin, George W

    2011-10-01

    Biofilm formation plays a critical role in the pathogenesis of Erwinia amylovora and the systemic invasion of plant hosts. The functional role of the exopolysaccharides amylovoran and levan in pathogenesis and biofilm formation has been evaluated. However, the role of biofilm formation, independent of exopolysaccharide production, in pathogenesis and movement within plants has not been studied previously. Evaluation of the role of attachment in E. amylovora biofilm formation and virulence was examined through the analysis of deletion mutants lacking genes encoding structures postulated to function in attachment to surfaces or in cellular aggregation. The genes and gene clusters studied were selected based on in silico analyses. Microscopic analyses and quantitative assays demonstrated that attachment structures such as fimbriae and pili are involved in the attachment of E. amylovora to surfaces and are necessary for the production of mature biofilms. A time course assay indicated that type I fimbriae function earlier in attachment, while type IV pilus structures appear to function later in attachment. Our results indicate that multiple attachment structures are needed for mature biofilm formation and full virulence and that biofilm formation facilitates entry and is necessary for the buildup of large populations of E. amylovora cells in xylem tissue.

  11. Ionizing Radiation Induces Macrophage Foam Cell Formation and Aggregation Through JNK-Dependent Activation of CD36 Scavenger Receptors

    SciTech Connect

    Katayama, Ikuo; Hotokezaka, Yuka; Matsuyama, Toshifumi; Sumi, Tadateru; Nakamura, Takashi

    2008-03-01

    Purpose: Irradiated arteries of cancer patients can be associated with atherosclerosis-like lesions containing cholesterol-laden macrophages (foam cells). Endothelial cell damage by irradiation does not completely explain the foam cell formation. We investigated the possible underlying mechanisms for ionizing radiation (IR)-induced foam cell formation. Methods and Materials: Human peripheral blood monocytes were activated by macrophage colony-stimulating factor and then treated with varying doses of IR in vitro in the absence of endothelial cells. Scavenger receptor expression and foam cell formation of IR-treated macrophages were investigated in the presence or absence of oxidized low-density lipoprotein. We also assessed the importance of mitogen-activated protein kinase activity in the macrophage colony-stimulating factor-activated human monocytes (macrophages) for the foam cell formation. Results: We found that IR treatment of macrophage colony-stimulating factor-activated human peripheral blood monocytes resulted in the enhanced expression of CD36 scavenger receptors and that cholesterol accumulated in the irradiated macrophages with resultant foam cell formation in the presence of oxidized low-density lipoprotein. Furthermore, when cultured on collagen gels, human macrophages formed large foam cell aggregates in response to IR. Antibodies against CD36 inhibited the IR-induced foam cell formation and aggregation, indicating that the IR-induced foam cell formation and the subsequent aggregation are dependent on functional CD36. In addition, we found that IR of human macrophages resulted in c-Jun N-terminal kinase activation and that c-Jun N-terminal kinase inhibition suppressed IR-induced CD36 expression and the subsequent foam cell formation and aggregation. Conclusion: Taken together, these results suggest that IR-induced foam cell formation is mediated by c-Jun N-terminal kinase-dependent CD36 activation.

  12. Translation suppression promotes stress granule formation and cell survival in response to cold shock

    PubMed Central

    Hofmann, Sarah; Cherkasova, Valeria; Bankhead, Peter; Bukau, Bernd; Stoecklin, Georg

    2012-01-01

    Cells respond to different types of stress by inhibition of protein synthesis and subsequent assembly of stress granules (SGs), cytoplasmic aggregates that contain stalled translation preinitiation complexes. Global translation is regulated through the translation initiation factor eukaryotic initiation factor 2α (eIF2α) and the mTOR pathway. Here we identify cold shock as a novel trigger of SG assembly in yeast and mammals. Whereas cold shock–induced SGs take hours to form, they dissolve within minutes when cells are returned to optimal growth temperatures. Cold shock causes eIF2α phosphorylation through the kinase PERK in mammalian cells, yet this pathway is not alone responsible for translation arrest and SG formation. In addition, cold shock leads to reduced mitochondrial function, energy depletion, concomitant activation of AMP-activated protein kinase (AMPK), and inhibition of mTOR signaling. Compound C, a pharmacological inhibitor of AMPK, prevents the formation of SGs and strongly reduces cellular survival in a translation-dependent manner. Our results demonstrate that cells actively suppress protein synthesis by parallel pathways, which induce SG formation and ensure cellular survival during hypothermia. PMID:22875991

  13. Cytochrome c-mediated formation of S-nitrosothiol in cells

    PubMed Central

    Broniowska, Katarzyna A.; Keszler, Agnes; Basu, Swati; Kim-Shapiro, Daniel B.; Hogg, Neil

    2014-01-01

    S-Nitrosothiols are products of nitric oxide metabolism that have been implicated in a plethora of signaling processes. However, mechanisms of S-nitrosothiol formation in biological systems are uncertain and no efficient protein-mediated process has been identified. Recently, we observed that ferric cytochrome c can promote S-nitrosoglutathione formation from nitric oxide and glutathione by acting as an electron acceptor under anaerobic conditions. In the current study we show that this mechanism also is robust under oxygenated conditions, that cytochrome c can promote protein S-nitrosation via a transnitrosation reaction, and that cell lysate depleted of cytochrome c exhibits lower capacity to synthesize S-nitrosothiols. Importantly, we also demonstrate that this mechanism is functional in living cells. Lower S-nitrosothiol synthesis activity, from donor and nitric oxide synthase-generated nitric oxide, was found in cytochrome c deficient mouse embryonic cells as compared to wild-type controls. In total, these data point to cytochrome c as a biological mediator of protein S-nitrosation in cells. This is the most efficient and concerted mechanism of S-nitrosothiol formation reported to date. PMID:22070099

  14. Serum amyloid A stimulates macrophage foam cell formation via lectin-like oxidized low-density lipoprotein receptor 1 upregulation

    SciTech Connect

    Lee, Ha Young; Kim, Sang Doo; Baek, Suk-Hwan; Choi, Joon Hyuk; Cho, Kyung-Hyun; Zabel, Brian A.; Bae, Yoe-Sik

    2013-03-29

    Highlights: ► SAA induced macrophage foam cell formation. ► SAA stimulated upregulation of lectin-like oxidized low-density lipoprotein receptor 1 (LOX1). ► SAA-induced LOX1 expression and foam cell formation is mediated by JNK/NF-κB signaling. ► HDL-conjugated SAA also stimulates foam cell formation via LOX1 upregulation. ► The finding reveals a novel mechanism of action of SAA in the pathogenesis of atherosclerosis. -- Abstract: Elevated levels of serum amyloid A (SAA) is a risk factor for cardiovascular diseases, however, the role of SAA in the pathophysiology of atherosclerosis remains unclear. Here we show that SAA induced macrophage foam cell formation. SAA-stimulated foam cell formation was mediated by c-jun N-terminal kinase (JNK) signaling. Moreover, both SAA and SAA-conjugated high density lipoprotein stimulated the expression of the important scavenger receptor lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) via nuclear factor-κB (NF-κB). A LOX1 antagonist carrageenan significantly blocked SAA-induced foam cell formation, indicating that SAA promotes foam cell formation via LOX1 expression. Our findings therefore suggest that SAA stimulates foam cell formation via LOX1 induction, and thus likely contributes to atherogenesis.

  15. Stromal cell-derived factor-1 potentiates bone morphogenetic protein-2 induced bone formation.

    PubMed

    Higashino, Kosaku; Viggeswarapu, Manjula; Bargouti, Maggie; Liu, Hui; Titus, Louisa; Boden, Scott D

    2011-02-01

    The mechanisms driving bone marrow stem cell mobilization are poorly understood. A recent murine study found that circulating bone marrow-derived osteoprogenitor cells (MOPCs) were recruited to the site of recombinant human bone morphogenetic protein-2 (BMP-2)-induced bone formation. Stromal cell-derived factor-1α (SDF-1α) and its cellular receptor CXCR4 have been shown to mediate the homing of stem cells to injured tissues. We hypothesized that chemokines, such as SDF-1, are also involved with mobilization of bone marrow cells. The CD45(-) fraction is a major source of MOPCs. In this report we determined that the addition of BMP-2 or SDF-1 to collagen implants increased the number of MOPCs in the peripheral blood. BMP-2-induced mobilization was blocked by CXCR4 antibody, confirming the role of SDF-1 in mobilization. We determined for the first time that addition of SDF-1 to implants containing BMP-2 enhances mobilization, homing of MOPCs to the implant, and ectopic bone formation induced by suboptimal BMP-2 doses. These results suggest that SDF-1 increases the number of osteoprogenitor cells that are mobilized from the bone marrow and then home to the implant. Thus, addition of SDF-1 to BMP-2 may improve the efficiency of BMPs in vivo, making their routine use for orthopaedic applications more affordable and available to more patients.

  16. Effect of chlorine dioxide on cyanobacterial cell integrity, toxin degradation and disinfection by-product formation.

    PubMed

    Zhou, Shiqing; Shao, Yisheng; Gao, Naiyun; Li, Lei; Deng, Jing; Zhu, Mingqiu; Zhu, Shumin

    2014-06-01

    Bench scale tests were conducted to study the effect of chlorine dioxide (ClO2) oxidation on cell integrity, toxin degradation and disinfection by-product formation of Microcystis aeruginosa. The simulated cyanobacterial suspension was prepared at a concentration of 1.0×10(6)cells/mL and the cell integrity was measured with flow cytometry. Results indicated that ClO2 can inhibit the photosynthetic capacity of M. aeruginosa cells and almost no integral cells were left after oxidation at a ClO2 dose of 1.0mg/L. The total toxin was degraded more rapidly with the ClO2 dosage increasing from 0.1mg/L to 1.0mg/L. Moreover, the damage on cell structure after oxidation resulted in released intracellular organic matter, which contributed to the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) as disinfection by-products. Therefore, the use of ClO2 as an oxidant for treating algal-rich water should be carefully considered.

  17. MTOC translocation modulates IS formation and controls sustained T cell signaling

    PubMed Central

    Martín-Cófreces, Noa B.; Robles-Valero, Javier; Cabrero, J. Román; Mittelbrunn, María; Gordón-Alonso, Mónica; Sung, Ching-Hwa; Alarcón, Balbino; Vázquez, Jesús; Sánchez-Madrid, Francisco

    2008-01-01

    The translocation of the microtubule-organizing center (MTOC) toward the nascent immune synapse (IS) is an early step in lymphocyte activation initiated by T cell receptor (TCR) signaling. The molecular mechanisms that control the physical movement of the lymphocyte MTOC remain largely unknown. We have studied the role of the dynein–dynactin complex, a microtubule-based molecular motor, in the process of T cell activation during T cell antigen–presenting cell cognate immune interactions. Impairment of dynein–dynactin complex activity, either by overexpressing the p50-dynamitin component of dynactin to disrupt the complex or by knocking down dynein heavy chain expression to prevent its formation, inhibited MTOC translocation after TCR antigen priming. This resulted in a strong reduction in the phosphorylation of molecules such as ζ chain–associated protein kinase 70 (ZAP70), linker of activated T cells (LAT), and Vav1; prevented the supply of molecules to the IS from intracellular pools, resulting in a disorganized and dysfunctional IS architecture; and impaired interleukin-2 production. Together, these data reveal MTOC translocation as an important mechanism underlying IS formation and sustained T cell signaling. PMID:18779373

  18. MTOC translocation modulates IS formation and controls sustained T cell signaling.

    PubMed

    Martín-Cófreces, Noa B; Robles-Valero, Javier; Cabrero, J Román; Mittelbrunn, María; Gordón-Alonso, Mónica; Sung, Ching-Hwa; Alarcón, Balbino; Vázquez, Jesús; Sánchez-Madrid, Francisco

    2008-09-08

    The translocation of the microtubule-organizing center (MTOC) toward the nascent immune synapse (IS) is an early step in lymphocyte activation initiated by T cell receptor (TCR) signaling. The molecular mechanisms that control the physical movement of the lymphocyte MTOC remain largely unknown. We have studied the role of the dynein-dynactin complex, a microtubule-based molecular motor, in the process of T cell activation during T cell antigen-presenting cell cognate immune interactions. Impairment of dynein-dynactin complex activity, either by overexpressing the p50-dynamitin component of dynactin to disrupt the complex or by knocking down dynein heavy chain expression to prevent its formation, inhibited MTOC translocation after TCR antigen priming. This resulted in a strong reduction in the phosphorylation of molecules such as zeta chain-associated protein kinase 70 (ZAP70), linker of activated T cells (LAT), and Vav1; prevented the supply of molecules to the IS from intracellular pools, resulting in a disorganized and dysfunctional IS architecture; and impaired interleukin-2 production. Together, these data reveal MTOC translocation as an important mechanism underlying IS formation and sustained T cell signaling.

  19. Prefoldin Protects Neuronal Cells from Polyglutamine Toxicity by Preventing Aggregation Formation*

    PubMed Central

    Tashiro, Erika; Zako, Tamotsu; Muto, Hideki; Itoo, Yoshinori; Sörgjerd, Karin; Terada, Naofumi; Abe, Akira; Miyazawa, Makoto; Kitamura, Akira; Kitaura, Hirotake; Kubota, Hiroshi; Maeda, Mizuo; Momoi, Takashi; Iguchi-Ariga, Sanae M. M.; Kinjo, Masataka; Ariga, Hiroyoshi

    2013-01-01

    Huntington disease is caused by cell death after the expansion of polyglutamine (polyQ) tracts longer than ∼40 repeats encoded by exon 1 of the huntingtin (HTT) gene. Prefoldin is a molecular chaperone composed of six subunits, PFD1–6, and prevents misfolding of newly synthesized nascent polypeptides. In this study, we found that knockdown of PFD2 and PFD5 disrupted prefoldin formation in HTT-expressing cells, resulting in accumulation of aggregates of a pathogenic form of HTT and in induction of cell death. Dead cells, however, did not contain inclusions of HTT, and analysis by a fluorescence correlation spectroscopy indicated that knockdown of PFD2 and PFD5 also increased the size of soluble oligomers of pathogenic HTT in cells. In vitro single molecule observation demonstrated that prefoldin suppressed HTT aggregation at the small oligomer (dimer to tetramer) stage. These results indicate that prefoldin inhibits elongation of large oligomers of pathogenic Htt, thereby inhibiting subsequent inclusion formation, and suggest that soluble oligomers of polyQ-expanded HTT are more toxic than are inclusion to cells. PMID:23720755

  20. Laticiferous canal formation in fruits of Decaisnea fargesii: a programmed cell death process?

    PubMed

    Zhou, Ya-Fu; Liu, Wen-Zhe

    2011-10-01

    Programmed cell death (PCD), a topic of abiding interest, remodels plants at the cell, tissue, and organ levels involving various developmental processes of plants. The aim of this study is to provide a morphological characterization of evidence of PCD involvement in the laticiferous canal formation in fruit of Decaisnea fargesii. Several ultrastructural features of PCD have been observed including disintegration of vacuole and plasma membranes, cell wall degeneration, degenerated cytoplasm, abundant membrane structures and flocculent material, mitochondria and misshapen nuclei coupled with degraded plastids in vacuoles, and nuclei enveloped by rubber granule. In D. fargesii, the nuclei of the secretory epidermal cells become TUNEL-positive from the sunken stage to the late expanding stage, then DAPI-negative during the mature stage, indicating an early event of deoxyribonucleic acid (DNA) cleavage and a late event of complete DNA degeneration. Gel electrophoresis indicates that DNA cleavage is random and does not result in the laddering pattern indicating multiples of internucleosomal units. During the PCD of secretory epidermal cells, the rubber granules continue to be synthesized and accumulated in the secretory epidermal cells despite nuclear degradation. The PCD's role in laticiferous canal formation suggests that PCD may play important roles in gland development of plants.

  1. CellH5: a format for data exchange in high-content screening

    PubMed Central

    Sommer, Christoph; Held, Michael; Fischer, Bernd; Huber, Wolfgang; Gerlich, Daniel W.

    2013-01-01

    Summary: High-throughput microscopy data require a diversity of analytical approaches. However, the construction of workflows that use algorithms from different software packages is difficult owing to a lack of interoperability. To overcome this limitation, we present CellH5, an HDF5 data format for cell-based assays in high-throughput microscopy, which stores high-dimensional image data along with inter-object relations in graphs. CellH5Browser, an interactive gallery image browser, demonstrates the versatility and performance of the file format on live imaging data of dividing human cells. CellH5 provides new opportunities for integrated data analysis by multiple software platforms. Availability: Source code is freely available at www.github.com/cellh5 under the GPL license and at www.bioconductor.org/packages/release/bioc/html/rhdf5.html under the Artistic-2.0 license. Demo datasets and the CellH5Browser are available at www.cellh5.org. A Fiji importer for cellh5 will be released soon. Contact: daniel.gerlich@imba.oeaw.ac.at or christoph.sommer@imba.oeaw.ac.at Supplementary information: Supplementary data are available at Bioinformatics online. PMID:23595665

  2. Online unsupervised formation of cell assemblies for the encoding of multiple cognitive maps.

    PubMed

    Salihoglu, Utku; Bersini, Hugues; Yamaguchi, Yoko; Molter, Colin

    2009-01-01

    Since their introduction sixty years ago, cell assemblies have proved to be a powerful paradigm for brain information processing. After their introduction in artificial intelligence, cell assemblies became commonly used in computational neuroscience as a neural substrate for content addressable memories. However, the mechanisms underlying their formation are poorly understood and, so far, there is no biologically plausible algorithms which can explain how external stimuli can be online stored in cell assemblies. We addressed this question in a previous paper [Salihoglu, U., Bersini, H., Yamaguchi, Y., Molter, C., (2009). A model for the cognitive map formation: Application of the retroaxonal theory. In Proc. IEEE international joint conference on neural networks], were, based on biologically plausible mechanisms, a novel unsupervised algorithm for online cell assemblies' creation was developed. The procedure involved simultaneously, a fast Hebbian/anti-Hebbian learning of the network's recurrent connections for the creation of new cell assemblies, and a slower feedback signal which stabilized the cell assemblies by learning the feedforward input connections. Here, we first quantify the role played by the retroaxonal feedback mechanism. Then, we show how multiple cognitive maps, composed by a set of orthogonal input stimuli, can be encoded in the network. As a result, when facing a previously learned input, the system is able to retrieve the cognitive map it belongs to. As a consequence, ambiguous inputs which could belong to multiple cognitive maps can be disambiguated by the knowledge of the context, i.e. the cognitive map.

  3. Neocartilage formation from mesenchymal stem cells grown in type II collagen-hyaluronan composite scaffolds.

    PubMed

    Yeh, Hsi-Yi; Lin, Ting-Yu; Lin, Chen-Huan; Yen, B Linju; Tsai, Ching-Lin; Hsu, Shan-Hui

    2013-01-01

    Three-dimensional (3D) collagen type II-hyaluronan (HA) composite scaffolds (CII-HA) which mimics the extracellular environment of natural cartilage were fabricated in this study. Rheological measurements demonstrated that the incorporation of HA increased the compression modulus of the scaffolds. An initial in vitro evaluation showed that scaffolds seeded with porcine chondrocytes formed cartilaginous-like tissue after 8 weeks, and HA functioned to promote the growth of chondrocytes into scaffolds. Placenta-derived multipotent cells (PDMC) and gingival fibroblasts (GF) were seeded on tissue culture polystyrene (TCPS), CII-HA films, and small intestinal submucosa (SIS) sheets for comparing their chondrogenesis differentiation potentials with those of adipose-derived adult stem cells (ADAS) and bone marrow-derived mesenchymal stem cells (BMSC). Among different cells, PDMC showed the greatest chondrogenic differentiation potential on both CII-HA films and SIS sheets upon TGF-β3 induction, followed by GF. This was evidenced by the up-regulation of chondrogenic genes (Sox9, aggrecan, and collagen type II), which was not observed for cells grown on TCPS. This finding suggested the essential role of substrate materials in the chondrogenic differentiation of PDMC and GF. Neocartilage formation was more obvious in both PDMC and GF cells plated on CII-HA composite scaffolds vs. 8-layer SIS at 28 days in vitro. Finally, implantation of PDMC/CII-HA constructs into NOD-SCID mice confirmed the formation of tissue-engineered cartilage in vivo.

  4. Wood Formation in Trees Is Increased by Manipulating PXY-Regulated Cell Division.

    PubMed

    Etchells, J Peter; Mishra, Laxmi S; Kumar, Manoj; Campbell, Liam; Turner, Simon R

    2015-04-20

    The woody tissue of trees is composed of xylem cells that arise from divisions of stem cells within the cambial meristem. The rate of xylem cell formation is dependent upon the rate of cell division within the cambium and is controlled by both genetic and environmental factors. In the annual plant Arabidopsis, signaling between a peptide ligand CLE41 and a receptor kinase PXY controls cambial cell divisions; however, the pathway regulating secondary growth in trees has not been identified. Here, we show that an aspen receptor kinase PttPXY and its peptide ligand PttCLE41 are functional orthologs and act to control a multifunctional pathway that regulates both the rate of cambial cell division and woody tissue organization. Ectopic overexpression of PttPXY and PttCLE41 genes in hybrid aspen resulted in vascular tissue abnormalities and poor plant growth. In contrast, precise tissue-specific overexpression generated trees that exhibited a 2-fold increase in the rate of wood formation, were taller, and possessed larger leaves compared to the controls. Our results demonstrate that the PXY-CLE pathway has evolved to regulate secondary growth and manipulating this pathway can result in dramatically increased tree growth and productivity.

  5. Zinc oxide nanoparticles induce migration and adhesion of monocytes to endothelial cells and accelerate foam cell formation

    SciTech Connect

    Suzuki, Yuka; Tada-Oikawa, Saeko; Ichihara, Gaku; Yabata, Masayuki; Izuoka, Kiyora; Suzuki, Masako; Sakai, Kiyoshi; Ichihara, Sahoko

    2014-07-01

    Metal oxide nanoparticles are widely used in industry, cosmetics, and biomedicine. However, the effects of exposure to these nanoparticles on the cardiovascular system remain unknown. The present study investigated the effects of nanosized TiO{sub 2} and ZnO particles on the migration and adhesion of monocytes, which are essential processes in atherosclerogenesis, using an in vitro set-up of human umbilical vein endothelial cells (HUVECs) and human monocytic leukemia cells (THP-1). We also examined the effects of exposure to nanosized metal oxide particles on macrophage cholesterol uptake and foam cell formation. The 16-hour exposure to ZnO particles increased the level of monocyte chemotactic protein-1 (MCP-1) and induced the migration of THP-1 monocyte mediated by increased MCP-1. Exposure to ZnO particles also induced adhesion of THP-1 cells to HUVECs. Moreover, exposure to ZnO particles, but not TiO{sub 2} particles, upregulated the expression of membrane scavenger receptors of modified LDL and increased cholesterol uptake in THP-1 monocytes/macrophages. In the present study, we found that exposure to ZnO particles increased macrophage cholesterol uptake, which was mediated by an upregulation of membrane scavenger receptors of modified LDL. These results suggest that nanosized ZnO particles could potentially enhance atherosclerogenesis and accelerate foam cell formation. - Highlights: • Effects of metal oxide nanoparticles on foam cell formation were investigated. • Exposure to ZnO nanoparticles induced migration and adhesion of monocytes. • Exposure to ZnO nanoparticles increased macrophage cholesterol uptake. • Expression of membrane scavenger receptors of modified LDL was also increased. • These effects were not observed after exposure to TiO{sub 2} nanoparticles.

  6. Homotypic cell competition regulates proliferation and tiling of zebrafish pigment cells during colour pattern formation

    PubMed Central

    Walderich, Brigitte; Singh, Ajeet Pratap; Mahalwar, Prateek; Nüsslein-Volhard, Christiane

    2016-01-01

    The adult striped pattern of zebrafish is composed of melanophores, iridophores and xanthophores arranged in superimposed layers in the skin. Previous studies have revealed that the assembly of pigment cells into stripes involves heterotypic interactions between all three chromatophore types. Here we investigate the role of homotypic interactions between cells of the same chromatophore type. Introduction of labelled progenitors into mutants lacking the corresponding cell type allowed us to define the impact of competitive interactions via long-term in vivo imaging. In the absence of endogenous cells, transplanted iridophores and xanthophores show an increased rate of proliferation and spread as a coherent net into vacant space. By contrast, melanophores have a limited capacity to spread in the skin even in the absence of competing endogenous cells. Our study reveals a key role for homotypic competitive interactions in determining number, direction of migration and individual spacing of cells within chromatophore populations. PMID:27118125

  7. Bioreactor cultivation enhances NTEB formation and differentiation of NTES cells into cardiomyocytes.

    PubMed

    Lü, Shuanghong; Liu, Sheng; He, Wenjun; Duan, Cuimi; Li, Yanmin; Liu, Zhiqiang; Zhang, Ye; Hao, Tong; Wang, Yanmeng; Li, Dexue; Wang, Changyong; Gao, Shaorong

    2008-09-01

    Autogenic embryonic stem cells established from somatic cell nuclear transfer (SCNT) embryos have been proposed as unlimited cell sources for cell transplantation-based treatment of many genetic and degenerative diseases, which can eliminate the immune rejection that occurs after transplantation. In the present study, pluripotent nuclear transfer ES (NTES) cell lines were successfully established from different strains of mice. One NTES cell line, NT1, with capacity of germline transmission, was used to investigate in vitro differentiation into cardiomyocytes. To optimize differentiation conditions for mass production of embryoid bodies (NTEBs) from NTES cells, a slow-turning lateral vessel (STLV) rotating bioreactor was used for culturing the NTES cells to produce NTEBs compared with a conventional static cultivation method. Our results demonstrated that the NTEBs formed in STLV bioreactor were more uniform in size, and no large necrotic centers with most of the cells in NTEBs were viable. Differentiation of the NTEBs formed in both the STLV bioreactor and static culture into cardiomyocytes was induced by ascorbic acid, and the results demonstrated that STLV-produced NTEBs differentiated into cardiomyocytes more efficiently. Taken together, our results suggested that STLV bioreactor provided a more ideal culture condition, which can facilitate the formation of better quality NTEBs and differentiation into cardiomyocytes more efficiently in vitro.

  8. The large GTPase dynamin regulates actin comet formation and movement in living cells

    PubMed Central

    Orth, James D.; Krueger, E. W.; Cao, H.; McNiven, Mark A.

    2002-01-01

    The large GTPase dynamin (Dyn2) has been demonstrated by us and others to interact with several different actin-binding proteins. To define how Dyn2 might participate in actin dynamics in livings cells we have expressed green fluorescent protein (GFP)-tagged Dyn2 in cultured cells and observed labeling of comet-like vesicles and macropinosomes. The comet structures progressed with a constant velocity and were reminiscent of actin comets associated with motile vesicles in cells expressing type I phosphatidylinositol phosphate 5-kinases. Based on these observations we sought to determine whether Dyn2 is an integral component of actin comets. Cells expressing type I phosphatidylinositol phosphate 5-kinase and Dyn2-GFP revealed a prominent colocalization of Dyn2 and actin in comet structures. Interestingly, comet formation and motility were normal in cells expressing wild-type Dyn2-GFP but altered markedly in Dyn2 mutant-expressing cells. Dyn2K44A-GFP mutant cells displayed a significant reduction in comet number, length, velocity, and efficiency of movement. In contrast, comets in cells expressing Dyn2ΔPRD-GFP appeared dark and did not incorporate the mutant Dyn2 protein, indicating that the proline-rich domain (PRD) is required for Dyn2 recruitment. Further, these comets were significantly longer and slower than those in control cells. These findings demonstrate a role for Dyn2 in actin-based vesicle motility. PMID:11782546

  9. Origin of germ cells and formation of new primary follicles in adult human ovaries

    PubMed Central

    Bukovsky, Antonin; Caudle, Michael R; Svetlikova, Marta; Upadhyaya, Nirmala B

    2004-01-01

    Recent reports indicate that functional mouse oocytes and sperm can be derived in vitro from somatic cell lines. We hypothesize that in adult human ovaries, mesenchymal cells in the tunica albuginea (TA) are bipotent progenitors with a commitment for both primitive granulosa and germ cells. We investigated ovaries of twelve adult women (mean age 32.8 ± 4.1 SD, range 27–38 years) by single, double, and triple color immunohistochemistry. We show that cytokeratin (CK)+ mesenchymal cells in ovarian TA differentiate into surface epithelium (SE) cells by a mesenchymal-epithelial transition. Segments of SE directly associated with ovarian cortex are overgrown by TA, forming solid epithelial cords, which fragment into small (20 micron) epithelial nests descending into the lower ovarian cortex, before assembling with zona pellucida (ZP)+ oocytes. Germ cells can originate from SE cells which cover the TA. Small (10 micron) germ-like cells showing PS1 meiotically expressed oocyte carbohydrate protein are derived from SE cells via asymmetric division. They show nuclear MAPK immunoexpression, subsequently divide symmetrically, and enter adjacent cortical vessels. During vascular transport, the putative germ cells increase to oocyte size, and are picked-up by epithelial nests associated with the vessels. During follicle formation, extensions of granulosa cells enter the oocyte cytoplasm, forming a single paranuclear CK+ Balbiani body supplying all the mitochondria of the oocyte. In the ovarian medulla, occasional vessels show an accumulation of ZP+ oocytes (25–30 microns) or their remnants, suggesting that some oocytes degenerate. In contrast to males, adult human female gonads do not preserve germline type stem cells. This study expands our previous observations on the formation of germ cells in adult human ovaries. Differentiation of primitive granulosa and germ cells from the bipotent mesenchymal cell precursors of TA in adult human ovaries represents a most

  10. Generation of cancer stem-like cells through the formation of polyploid giant cancer cells.

    PubMed

    Zhang, S; Mercado-Uribe, I; Xing, Z; Sun, B; Kuang, J; Liu, J

    2014-01-02

    Polyploid giant cancer cells (PGCCs) have been observed by pathologists for over a century. PGCCs contribute to solid tumor heterogeneity, but their functions are largely undefined. Little attention has been given to these cells, largely because PGCCs have been generally thought to originate from repeated failure of mitosis/cytokinesis and have no capacity for long-term survival or proliferation. Here we report our successful purification and culture of PGCCs from human ovarian cancer cell lines and primary ovarian cancer. These cells are highly resistant to oxygen deprivation and could form through endoreduplication or cell fusion, generating regular-sized cancer cells quickly through budding or bursting similar to simple organisms like fungi. They express normal and cancer stem cell markers, they divide asymmetrically and they cycle slowly. They can differentiate into adipose, cartilage and bone. A single PGCC formed cancer spheroids in vitro and generated tumors in immunodeficient mice. These PGCC-derived tumors gained a mesenchymal phenotype with increased expression of cancer stem cell markers CD44 and CD133 and become more resistant to treatment with cisplatin. Taken together, our results reveal that PGCCs represent a resistant form of human cancer using an ancient, evolutionarily conserved mechanism in response to hypoxia stress; they can contribute to the generation of cancer stem-like cells, and also play a fundamental role in regulating tumor heterogeneity, tumor growth and chemoresistance in human cancer.

  11. An endogenous protein inhibitor, YjhX (TopAI), for topoisomerase I from Escherichia coli

    PubMed Central

    Yamaguchi, Yoshihiro; Inouye, Masayori

    2015-01-01

    Almost all free-living bacteria contain toxin-antitoxin (TA) systems on their genomes and the targets of toxins are highly diverse. Here, we found a novel, previously unidentified TA system in Escherichia coli named yjhX-yjhQ. Induction of YjhX (85 amino acid residues) causes cell-growth arrest resulting in cell death, while YjhQ (181 residues) co-induction resumes cell growth. The primary cellular target of YjhX was found to be topoisomerase I (TopA), inhibiting both DNA replication and RNA synthesis. Notably, YjhX has no homology to any other toxins of the TA systems. YjhX was expressed well with an N-terminal protein S (PrS) tag in soluble forms. PrS-YjhX specifically interacts with the N-terminal region of TopA (TopA67) but not full-TopA in the absence of plasmid DNA, while PrS-YjhX binds to full-TopA in the presence of DNA. Notably, YjhX does not directly interact with DNA and RNA. YjhX inhibits only topoisomerase I but not topoisomerase III and IV in vitro. Hence, yjhX is renamed as the gene for the TopA inhibitor (the topAI gene). TopAI is the first endogenous protein inhibitor specific for topoisomerase I. PMID:26553797

  12. Laminin-521 Promotes Rat Bone Marrow Mesenchymal Stem Cell Sheet Formation on Light-Induced Cell Sheet Technology

    PubMed Central

    2017-01-01

    Rat bone marrow mesenchymal stem cell sheets (rBMSC sheets) are attractive for cell-based tissue engineering. However, methods of culturing rBMSC sheets are critically limited. In order to obtain intact rBMSC sheets, a light-induced cell sheet method was used in this study. TiO2 nanodot films were coated with (TL) or without (TN) laminin-521. We investigated the effects of laminin-521 on rBMSCs during cell sheet culturing. The fabricated rBMSC sheets were subsequently assessed to study cell sheet viability, reattachment ability, cell sheet thickness, collagen type I deposition, and multilineage potential. The results showed that laminin-521 could promote the formation of rBMSC sheets with good viability under hyperconfluent conditions. Cell sheet thickness increased from an initial 26.7 ± 1.5 μm (day 5) up to 47.7 ± 3.0 μm (day 10). Moreover, rBMSC sheets maintained their potential of osteogenic, adipogenic, and chondrogenic differentiation. This study provides a new strategy to obtain rBMSC sheets using light-induced cell sheet technology. PMID:28164129

  13. JAM-A and aPKC: A close pair during cell-cell contact maturation and tight junction formation in epithelial cells.

    PubMed

    Ebnet, Klaus

    2013-01-01

    Cell-cell adhesion plays a critical role in the formation of barrier-forming epithelia. The molecules which mediate cell-cell adhesion frequently act as signaling molecules by recruiting and/or assembling cytoplasmic protein complexes. Junctional Adhesion Molecule (JAM)-A interacts with the cell polarity protein PAR-3, a member of the PAR-3-aPKC-PAR-6 complex, which regulates the formation of cell-cell contacts and the development of tight junctions (TJs). In our recent study we found that JAM-A is localized at primordial, spot-like cell-cell junctions (pAJs) in a non-phosphorylated form. After the recruitment of the PAR-aPKC complex and its activation at pAJs, aPKC phosphorylates JAM-A at Ser285 to promote the maturation of immature junctions. In polarized epithelial cells, aPKC phosphorylates JAM-A selectively at the TJs to maintain the barrier function of TJs. Thus, through mutual regulation, JAM-A and aPKC form a functional unit that regulates the establishment of barrier-forming junctions in vertebrate epithelial cells.

  14. An in vitro coculture model of transmigrant monocytes and foam cell formation.

    PubMed

    Takaku, M; Wada, Y; Jinnouchi, K; Takeya, M; Takahashi, K; Usuda, H; Naito, M; Kurihara, H; Yazaki, Y; Kumazawa, Y; Okimoto, Y; Umetani, M; Noguchi, N; Niki, E; Hamakubo, T; Kodama, T

    1999-10-01

    To analyze in vitro the migration of monocytes to the subendothelial space, their differentiation into macrophages, and the subsequent formation of foam cells in vitro, we have developed a 2-coculture system with rabbit aortic endothelial cells (AECs), aortic smooth muscle cells (SMCs), and a mixture of matrix proteins on polyethylene filters in chemotaxis chambers. AECs were seeded on a mixture of type I and IV collagen with or without various types of serum lipoproteins (method 1) or on matrix proteins secreted by SMCs (method 2). In these coculture systems, rabbit AECs can maintain a well-preserved monolayer for up to 2 weeks. When human CD14-positive monocytes were added to the upper medium of the system, with monocyte chemotactic protein-1 treatment approximately 60% of the monocytes transmigrated within 24 hours and were retained for up to 7 days, whereas without MCP-1 treatment, <30% of monocytes transmigrated. On day 1, transmigrant monocytes were negative for immunostaining of type I and II macrophage scavenger receptors but by day 3, became positive for scavenger receptors as well as other macrophage markers. When oxidized low density lipoprotein was added to the matrix layer of the method I coculture, on day 4 transmigrant cells exhibited lipid deposit droplets, and by day 7, they had the appearance of typical foam cells. Some of the transmigrant cells recovered in the lower medium on day 7 also appeared to be foam cells, indicating foam cell motility and escape from the coculture layer through the filter. In summary, this coculture system is a useful in vitro tool to dissect the cellular and molecular events that make up the process of foam cell formation.

  15. Synergy in biofilm formation between Fusobacterium nucleatum and Prevotella species.

    PubMed

    Okuda, Tamaki; Kokubu, Eitoyo; Kawana, Tomoko; Saito, Atsushi; Okuda, Katsuji; Ishihara, Kazuyuki

    2012-02-01

    The formation of biofilm by anaerobic, Gram-negative bacteria in the subgingival crevice plays an important role in the development of chronic periodontitis. The aim of this study was to characterize the role of coaggregation between Fusobacterium nucleatum and Prevotella species in biofilm formation. Coaggregation between F. nucleatum and Prevotella species was determined by visual assay. Effect of co-culture of the species on biofilm formation was assessed by crystal violet staining. Effect of soluble factor on biofilm formation was also examined using culture supernatant and two-compartment co-culture separated by a porous membrane. Production of autoinducer-2 (AI-2) by the organisms was evaluated using Vibrio harveyi BB170. Cells of all F. nucleatum strains coaggregated with Prevotella intermedia or Prevotella nigrescens with a score of 1-4. Addition of ethylenediamine tetraacetic acid or l-lysine inhibited coaggregation. Coaggregation disappeared after heating of P. intermedia or P. nigrescens cells, or Proteinase K treatment of P. nigrescens cells. Co-culture of F. nucleatum ATCC 25586 with P. intermedia or P. nigrescens strains increased biofilm formation compared with single culture (p < 0.01); co-culture with culture supernatant of these strains, however, did not enhance biofilm formation by F. nucleatum. Production of AI-2 in Prevotella species was not related to enhancement of biofilm formation by F. nucleatum. These findings indicate that physical contact by coaggregation of F. nucleatum strains with P. intermedia or P. nigrescens plays a key role in the formation of biofilm by these strains.

  16. Mechanism of Pinhole Formation in Membrane Electrode Assemblies for PEM Fuel Cells

    NASA Technical Reports Server (NTRS)

    Stanic, Vesna; Hoberecht, Mark

    2004-01-01

    The pinhole formation mechanism was studied with a variety of MEAs using ex-situ and in-situ methods. The ex-situ tests included the MEA aging in oxygen and MEA heat of ignition. In-situ durability tests were performed in fuel cells at different operating conditions with hydrogen and oxygen. After the in-situ failure, MEAs were analyzed with an Olympus BX 60 optical microscope and Cambridge 120 scanning electron microscope. MEA chemical analysis was performed with an IXRF EDS microanalysis system. The MEA failure analyses showed that pinholes and tears were the MEA failure modes. The pinholes appeared in MEA areas where the membrane thickness was drastically reduced. Their location coincided with the stress concentration points, indicating that membrane creep was responsible for their formation. Some of the pinholes detected had contaminant particles precipitated within the membrane. This mechanism of pinhole formation was correlated to the polymer blistering.

  17. Sialic Acid on the Glycosylphosphatidylinositol Anchor Regulates PrP-mediated Cell Signaling and Prion Formation*

    PubMed Central

    Bate, Clive; Nolan, William; Williams, Alun

    2016-01-01

    The prion diseases occur following the conversion of the cellular prion protein (PrPC) into disease-related isoforms (PrPSc). In this study, the role of the glycosylphosphatidylinositol (GPI) anchor attached to PrPC in prion formation was examined using a cell painting technique. PrPSc formation in two prion-infected neuronal cell lines (ScGT1 and ScN2a cells) and in scrapie-infected primary cortical neurons was increased following the introduction of PrPC. In contrast, PrPC containing a GPI anchor from which the sialic acid had been removed (desialylated PrPC) was not converted to PrPSc. Furthermore, the presence of desialylated PrPC inhibited the production of PrPSc within prion-infected cortical neurons and ScGT1 and ScN2a cells. The membrane rafts surrounding desialylated PrPC contained greater amounts of sialylated gangliosides and cholesterol than membrane rafts surrounding PrPC. Desialylated PrPC was less sensitive to cholesterol depletion than PrPC and was not released from cells by treatment with glimepiride. The presence of desialylated PrPC in neurons caused the dissociation of cytoplasmic phospholipase A2 from PrP-containing membrane rafts and reduced the activation of cytoplasmic phospholipase A2. These findings show that the sialic acid moiety of the GPI attached to PrPC modifies local membrane microenvironments that are important in PrP-mediated cell signaling and PrPSc formation. These results suggest that pharmacological modification of GPI glycosylation might constitute a novel therapeutic approach to prion diseases. PMID:26553874

  18. Cancer stem cell marker CD90 inhibits ovarian cancer formation via β3 integrin

    PubMed Central

    Chen, Wei-Ching; Hsu, Hui-Ping; Li, Chung-Yen; Yang, Ya-Ju; Hung, Yu-Hsuan; Cho, Chien-Yu; Wang, Chih-Yang; Weng, Tzu-Yang; Lai, Ming-Derg

    2016-01-01

    Cancer stem cell (CSC) markers have been identified for CSC isolation and proposed as therapeutic targets in various types of cancers. CD90, one of the characterized markers in liver and gastric cancer, is shown to promote cancer formation. However, the underexpression level of CD90 in ovarian cancer cells and the evidence supporting the cellular mechanism have not been investigated. In the present study, we found that the DNA copy number of CD90 is correlated with mRNA expression in ovarian cancer tissue and the ovarian cancer patients with higher CD90 have good prognosis compared to the patients with lower CD90. Although the expression of CD90 in human ovarian cancer SKOV3 cells enhances the cell proliferation by MTT and anchorage-dependent growth assay, CD90 inhibits the anchorage-independent growth ability in vitro and tumor formation in vivo. CD90 overexpression suppresses the sphere-forming ability and ALDH activity and enhances the cell apoptosis, indicating that CD90 may reduce the cell growth by the properties of CSC and anoikis. Furthermore, CD90 reduces the expression of other CSC markers, including CD133 and CD24. The inhibition of CD133 is attenuated by the mutant CD90, which is replaced with RLE domain into RLD domain. Importantly, the CD90-regulated inhibition of CD133 expression, anchorage-independent growth and signal transduction of mTOR and AMPK are restored by the β3 integrin shRNA. Our results provide evidence that CD90 mediates the antitumor formation by interacting with β3 integrin, which provides new insight that can potentially be applied in the development of therapeutic strategies in ovarian cancer. PMID:27633757

  19. High glucose induces cell death of cultured human aortic smooth muscle cells through the formation of hydrogen peroxide

    PubMed Central

    Peiró, Concepción; Lafuente, Nuria; Matesanz, Nuria; Cercas, Elena; Llergo, José L; Vallejo, Susana; Rodríguez-Mañas, Leocadio; Sánchez-Ferrer, Carlos F

    2001-01-01

    Alterations of the vessel structure, which is mainly determined by smooth muscle cells through cell growth and/or cell death mechanisms, are characteristic of diabetes complications. We analysed the influence of high glucose (22 mM) on cultured human aortic smooth muscle cell growth and death, as hyperglycaemia is considered one of the main factors involved in diabetic vasculopathy. Growth curves were performed over 96 h in medium containing 0.5% foetal calf serum. Cell number increased by 2–4 fold over the culture period in the presence of 5.5 mM (low) glucose, while a 20% reduction in final cell number was observed with high glucose. Under serum-free conditions, cell number remained constant in low glucose cultures, but a 40% decrease was observed in high glucose cultures, suggesting that high glucose may induce increased cell death rather than reduced proliferation. Reduced final cell number induced by high glucose was also observed after stimulation with 5 or 10% foetal calf serum. The possible participation of oxidative stress was investigated by co-incubating high glucose with different reactive oxygen species scavengers. Only catalase reversed the effect of high glucose. Intracellular H2O2 content, visualized with 2′,7′-dichlorofluorescein and quantified by flow cytometry, was increased after high glucose treatment. To investigate the cell death mechanism induced by high glucose, apoptosis and necrosis were quantified. No differences were observed regarding the apoptotic index between low and high glucose cultures, but lactate dehydrogenase activity was increased in high glucose cultures. In conclusion, high glucose promotes necrotic cell death through H2O2 formation, which may participate in the development of diabetic vasculopathy. PMID:11487505

  20. Cell-directed-assembly: Directing the formation of nano/bio interfaces and architectures with living cells

    PubMed Central

    Baca, Helen K.; Carnes, Eric C.; Ashley, Carlee E.; Lopez, DeAnna M.; Douthit, Cynthia; Karlin, Shelly; Brinker, C. Jeffrey

    2011-01-01

    Background The desire to immobilize, encapsulate, or entrap viable cells for use in a variety of applications has been explored for decades. Traditionally, the approach is to immobilize cells to utilize a specific functionality of the cell in the system. Scope of Review This review describes our recent discovery that living cells can organize extended nanostructures and nano-objects to create a highly biocompatible nano//bio interface [1]. Major Conclusions We find that short chain phospholipids direct the formation of thin film silica mesophases during evaporation-induced self-assembly (EISA) [2], and that the introduction of cells alter the self-assembly pathway. Cells organize an ordered lipid-membrane that forms a coherent interface with the silica mesophase that is unique in that it withstands drying - yet it maintains accessibility to molecules introduced into the 3D silica host. Cell viability is preserved in the absence of buffer, making these constructs useful as standalone cell-based sensors. In response to hyperosmotic stress, the cells release water, creating a pH gradient which is maintained within the nanostructured host and serves to localize lipids, proteins, plasmids, lipidized nanocrystals, and other components at the cellular surface. This active organization of the bio/nano interface can be accomplished during ink-jet printing or selective wetting - processes allowing patterning of cellular arrays - and even spatially-defined genetic modification. General Significance Recent advances in the understanding of nanotechnology and cell biology encourage the pursuit of more complex endeavors where the dynamic interactions of the cell and host material act symbiotically to obtain new, useful functions. PMID:20933574

  1. Regenerative amacrine cell depolarization and formation of on-off ganglion cell response.

    PubMed Central

    Werblin, F S

    1977-01-01

    1. Recordings from amacrine and ganglion cells in the mudpuppy retina suggest mechanisms whereby the relatively slow, sustained light responses measured in bipolar cells are converted to rapid, brief, transient activity in the on-off ganglion cells. 2. Double-barrel electrodes were used to control the membrane potential under voltage clamp. The clamp revealed synaptic currents, but eliminated the otherwise obvious spike activity elicited by steps of illumination in both amacrine and ganglion cells, suggesting that the spikes are initiated near the somata. 3. The synaptic current in the on-off ganglion cells was biphasic: a brief inward (depolarizing) membrane current preceded a transient outward (hyperpolarizing) membrane current by about 20 msec. Each component could be isolated by polarizing the membrane to a level near the reversal potential for the other. Each was apparently due to a transient conductance increase of sawtooth shape with a 40 msec time to peak and a decay longer than 400 msec. 4. Synaptic membrane current in amacrine cells was monophasic and inward (depolarizing) of similar sawtooth shape at all potential levels. It was apparently mediated by a conductance increase to ions with a reversal potential more positive than the dark level. 5. When amacrine cells were depolarized in the dark under voltage clamp, a large transient inward membrane current with threshold within 4 mV of the dark level was generated. This regenerative event is capable of boosting a small, 4 mV e.p.s.p. to more than 30 mV in a few milliseconds, thereby generating the leading edge of a rapid sawtooth response. 6. The results suggest that the rapid transient on-off activity in ganglion cells is mediated by opposing sawtooth shaped synaptic currents with different latencies. It is inferred that each of these antagonistic imputs is generated by a regenerative depolarization in amacrine cells which then form synaptic inputs to the ganglion cells. PMID:845823

  2. Anthrax edema toxin inhibits Nox1-mediated formation of reactive oxygen species by colon epithelial cells.

    PubMed

    Kim, Jun-Sub; Bokoch, Gary M

    2009-01-01

    One major route of intoxication by Bacillus anthracis (anthrax) spores is via their ingestion and subsequent uptake by the intestinal epithelium. Anthrax edema toxin (ETx) is an adenylate cyclase that causes persistent elevation of cAMP in intoxicated cells. NADPH oxidase enzymes (Nox1-Nox5, Duox1 and 2) generate reactive oxygen species (ROS) as components of the host innate immune response to bacteria, including Nox1 in gastrointestinal epithelial tissues. We show that ETx effectively inhibits ROS formation by Nox1 in HT-29 colon epithelial cells. This inhibition requires the PKA-mediated phosphorylation of the Nox1-regulatory component, NoxA1, and the subsequent binding of 14-3-3zeta. Inhibition of Nox1-mediated ROS formation in the gut epithelium may be a mechanism used by B. anthracis to circumvent the innate immune response.

  3. ATP-Dependent Formation of Phosphatidylserine-Rich Vesicles from the Endoplasmic Reticulum of Leek Cells

    PubMed Central

    Sturbois-Balcerzak, Bénédicte; Vincent, Patrick; Maneta-Peyret, Lilly; Duvert, Michel; Satiat-Jeunemaitre, Béatrice; Cassagne, Claude; Moreau, Patrick

    1999-01-01

    Leek (Allium porrum) plasma membrane is enriched in phosphatidylserine (PS) by the vesicular pathway, in a way similar to that already observed in animal cells (B. Sturbois-Balcerzak, D.J. Morré, O. Loreau, J.P. Noel, P. Moreau, C. Cassagne [1995] Plant Physiol Biochem 33: 625–637). In this paper we document the formation of PS-rich small vesicles from leek endoplasmic reticulum (ER) membranes upon addition of ATP and other factors. The omission of ATP or its replacement by ATPγ-S prevents vesicle formation. These vesicles correspond to small structures (70–80 nm) and their phospholipid composition, characterized by a PS enrichment, is compatible with a role in PS transport. Moreover, the PS enrichment over phosphatidylinositol in the ER-derived vesicles is the first example, to our knowledge, of phospholipid sorting from the ER to ER-derived vesicles in plant cells. PMID:10318702

  4. Flow-induced channel formation in the cytoplasm of motile cells

    NASA Astrophysics Data System (ADS)

    Guy, Robert D.; Nakagaki, Toshiyuki; Wright, Grady B.

    2011-07-01

    A model is presented to explain the development of flow channels within the cytoplasm of the plasmodium of the giant amoeba Physarum polycephalum. The formation of channels is related to the development of a self-organizing tubular network in large cells. Experiments indicate that the flow of cytoplasm is involved in the development and organization of these networks, and the mathematical model proposed here is motivated by recent experiments involving the observation of development of flow channel in small cells. A model of pressure-driven flow through a polymer network is presented in which the rate of flow increases the rate of depolymerization. Numerical solutions and asymptotic analysis of the model in one spatial dimension show that under very general assumptions this model predicts the formation of channels in response to flow.

  5. Cranial Neural Crest Cell Contribution to Craniofacial Formation, Pathology, and Future Directions in Tissue Engineering

    PubMed Central

    Snider, Taylor Nicholas; Mishina, Yuji

    2015-01-01

    This review provides an overview of the state and future directions of development and pathology in the craniofacial complex in the context of Cranial Neural Crest Cells (CNCC). CNCC are a multipotent cell population that is largely responsible for forming the vertebrate head. We focus on findings that have increased the knowledge of gene regulatory networks and molecular mechanisms governing CNCC migration and the participation of these cells in tissue formation. Pathology due to aberrant migration or cell death of CNCC, termed neurocristopathies, is discussed in addition to craniosynostoses. Finally, we discuss tissue engineering applications that take advantage of recent advancements in genome editing and the multipotent nature of CNCC. These applications have relevance to treating diseases due directly to the failure of CNCC, and also in restoring tissues lost due to a variety of reasons. PMID:25227212

  6. A sample cell to study hydrate formation with x-ray scattering.

    PubMed

    Conrad, Heiko; Lehmkühler, Felix; Sternemann, Christian; Feroughi, Omid; Simonelli, Laura; Huotari, Simo; Tolan, Metin

    2009-02-01

    We present a new sample cell for measuring nonresonant inelastic x-ray scattering spectra of a tetrahydrofuran (THF)-water liquid mixture and THF hydrate. The hydrate is formed inside the cell after nucleation seeds have been offered by a special magnetic stirring mechanism. Hydrate formation was verified by wide angle x-ray scattering and nonresonant x-ray Raman scattering spectra at the oxygen K-edge. A broad range of scattering angles can be studied with this cell which is necessary for momentum transfer dependent inelastic x-ray scattering. This cell is ideal to examine other liquid hydrate formers or other liquid samples, which have to be mixed in situ during the measurements.

  7. A sample cell to study hydrate formation with x-ray scattering

    SciTech Connect

    Conrad, Heiko; Lehmkuehler, Felix; Sternemann, Christian; Feroughi, Omid; Tolan, Metin

    2009-02-15

    We present a new sample cell for measuring nonresonant inelastic x-ray scattering spectra of a tetrahydrofuran (THF)-water liquid mixture and THF hydrate. The hydrate is formed inside the cell after nucleation seeds have been offered by a special magnetic stirring mechanism. Hydrate formation was verified by wide angle x-ray scattering and nonresonant x-ray Raman scattering spectra at the oxygen K-edge. A broad range of scattering angles can be studied with this cell which is necessary for momentum transfer dependent inelastic x-ray scattering. This cell is ideal to examine other liquid hydrate formers or other liquid samples, which have to be mixed in situ during the measurements.

  8. Cytoprotective effect of imatinib mesylate in non-BCR-ABL-expressing cells along with autophagosome formation

    SciTech Connect

    Ohtomo, Tadashi; Miyazawa, Keisuke; Naito, Munekazu; Moriya, Shota; Kuroda, Masahiko; Itoh, Masahiro; Tomoda, Akio

    2010-01-01

    Treatment with imatinib mesylate (IM) results in an increased viable cell number of non-BCR-ABL-expressing cell lines by inhibiting spontaneous apoptosis. Electron microscopy revealed an increase of autophagosomes in response to IM. IM attenuated the cytotoxic effect of cytosine arabinoside, as well as inhibiting cell death with serum-deprived culture. Cytoprotection with autophagosome formation by IM was observed in various leukemia and cancer cell lines as well as normal murine embryonic fibroblasts (MEFs). Complete inhibition of autophagy by knockdown of atg5 in the Tet-off atg5{sup -/-} MEF system attenuated the cytoprotective effect of IM, indicating that the effect is partially dependent on autophagy. However, cytoprotection by IM was not mediated through suppression of ROS production via mitophagy, ER stress via ribophagy, or proapoptotic function of ABL kinase. Although the target tyrosine kinase(s) of IM remains unclear, our data provide novel therapeutic possibilities of using IM for cytoprotection.

  9. Viral contamination of a mosquito cell line, Aedes albopictus, associated with syncytium formation.

    PubMed

    Hirumi, H; Hirumi, K; Speyer, G; Yunker, C E; Thomas, L A; Cory, J; Sweet, B H

    1976-02-01

    Viral contamination associated with syncytium formation in two sbulines of Singh's Aedes albopictus cell cultures was investigated. Electron microscopy of the syncytia revealed the presence of five different types of virus-like particles, which morphologically resembled the parvo-, picorna-, toga-, and orbi-, and bacterial viruses. When a virus-free subline of the A. albopictus cells (SL3) was inoculated with extracts of the syncytium-forming A. albopictus cells, the parvo-, toga-, and orbi-type viral agents were consistently observed. Among these three agents, the togavirus-type agent is most likely responsible for the syncytium induction. Serological examination of the infected cell extract indicated that at least one of three virus-like agents, presumably the togavirus-type agent, was related to Chikungunya. O'nyong-nyong, and Western equine encephalomyelitis viruses (alphaviruses of the Togaviridae), but separable from these.

  10. 78 FR 17232 - Meeting of the SANE/SART AI/AN Initiative Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... Indian/ Alaska Native (AI/AN) Sexual Assault Nurse Examiner (SANE)--Sexual Assault Response Team (SART.../Alaskan Native (AI/AN) Sexual Assault Nurse Examiner (SANE)--Sexual Assault Response Team...

  11. CD8 T Cells Are Required for the Formation of Ectopic Germinal Centers in Rheumatoid Synovitis

    PubMed Central

    Kang, Young Mo; Zhang, Xiaoyu; Wagner, Ulf G.; Yang, Hongyu; Beckenbaugh, Robert D.; Kurtin, Paul J.; Goronzy, Jörg J.; Weyand, Cornelia M.

    2002-01-01

    The assembly of inflammatory lesions in rheumatoid arthritis is highly regulated and typically leads to the formation of lymphoid follicles with germinal center (GC) reactions. We used microdissection of such extranodal follicles to analyze the colonizing T cells. Although the repertoire of follicular T cells was diverse, a subset of T cell receptor (TCR) sequences was detected in multiple independent follicles and not in interfollicular zones, suggesting recognition of a common antigen. Unexpectedly, the majority of shared TCR sequences were from CD8 T cells that were highly enriched in the synovium and present in low numbers in the periphery. To examine their role in extranodal GC reactions, CD8 T cells were depleted in human synovium-SCID mouse chimeras. Depletion of synovial CD8 T cells caused disintegration of the GC-containing follicles. In the absence of CD8 T cells, follicular dendritic cells disappeared, production of lymphotoxin-α1β2 markedly decreased, and immunoglobulin (Ig) secretion ceased. Immunohistochemical studies demonstrated that these CD8 T cells accumulated at the edge of the mantle zone. Besides their unique localization, they were characterized by the production of interferon (IFN)-γ, lack of the pore-forming enzyme perforin, and expression of CD40 ligand. Perifollicular IFN-γ+ CD8 T cells were rare in secondary lymphoid tissues but accounted for the majority of IFN-γ+ cells in synovial infiltrates. We propose that CD8+ T cells regulate the structural integrity and functional activity of GCs in ectopic lymphoid follicles. PMID:12021312

  12. Spatio-temporal analysis of cellulose synthesis during cell plate formation in Arabidopsis.

    PubMed

    Miart, Fabien; Desprez, Thierry; Biot, Eric; Morin, Halima; Belcram, Katia; Höfte, Herman; Gonneau, Martine; Vernhettes, Samantha

    2014-01-01

    During cytokinesis a new crosswall is rapidly laid down. This process involves the formation at the cell equator of a tubulo-vesicular membrane network (TVN). This TVN evolves into a tubular network (TN) and a planar fenestrated sheet, which extends at its periphery before fusing to the mother cell wall. The role of cell wall polymers in cell plate assembly is poorly understood. We used specific stains and GFP-labelled cellulose synthases (CESAs) to show that cellulose, as well as three distinct CESAs, accumulated in the cell plate already at the TVN stage. This early presence suggests that cellulose is extruded into the tubular membrane structures of the TVN. Co-localisation studies using GFP-CESAs suggest the delivery of cellulose synthase complexes (CSCs) to the cell plate via phragmoplast-associated vesicles. In the more mature TN part of the cell plate, we observed delivery of GFP-CESA from doughnut-shaped organelles, presumably Golgi bodies. During the conversion of the TN into a planar fenestrated sheet, the GFP-CESA density diminished, whereas GFP-CESA levels remained high in the TVN zone at the periphery of the expanding cell plate. We observed retrieval of GFP-CESA in clathrin-containing structures from the central zone of the cell plate and from the plasma membrane of the mother cell, which may contribute to the recycling of CESAs to the peripheral growth zone of the cell plate. These observations, together with mutant phenotypes of cellulose-deficient mutants and pharmacological experiments, suggest a key role for cellulose synthesis already at early stages of cell plate assembly.

  13. A Distinct Pathway for Polar Exocytosis in Plant Cell Wall Formation1[OPEN

    PubMed Central

    Wang, Hao; Zhuang, Xiaohong; Wang, Xiangfeng; Law, Angus Ho Yin; Zhao, Teng; Du, Shengwang; Loy, Michael M.T.; Jiang, Liwen

    2016-01-01

    Post-Golgi protein sorting and trafficking to the plasma membrane (PM) is generally believed to occur via the trans-Golgi network (TGN). In this study using Nicotiana tabacum pectin methylesterase (NtPPME1) as a marker, we have identified a TGN-independent polar exocytosis pathway that mediates cell wall formation during cell expansion and cytokinesis. Confocal immunofluorescence and immunogold electron microscopy studies demonstrated that Golgi-derived secretory vesicles (GDSVs) labeled by NtPPME1-GFP are distinct from those organelles belonging to the conventional post-Golgi exocytosis pathway. In addition, pharmaceutical treatments, superresolution imaging, and dynamic studies suggest that NtPPME1 follows a polar exocytic process from Golgi-GDSV-PM/cell plate (CP), which is distinct from the conventional Golgi-TGN-PM/CP secretion pathway. Further studies show that ROP1 regulates this specific polar exocytic pathway. Taken together, we have demonstrated an alternative TGN-independent Golgi-to-PM polar exocytic route, which mediates secretion of NtPPME1 for cell wall formation during cell expansion and cytokinesis and is ROP1-dependent. PMID:27531442

  14. Ultrastructure and behavior of actin cytoskeleton during cell wall formation in the fission yeast Schizosaccharomyces pombe.

    PubMed

    Takagi, Tomoko; Ishijima, Sanae A; Ochi, Hisako; Osumi, Masako

    2003-01-01

    Fluorescence microscopy has shown that F-actin of the fission yeast Schizosaccharomyces pombe forms patch, cable and ring structures. To study the relationship between cell wall formation and the actin cytoskeleton, the process of cell wall regeneration from the protoplast was investigated by transmission electron microscopy (TEM), immunoelectron microscopy (IEM) and three-dimensional reconstruction analysis. During cell wall regeneration from the protoplast, localization of F-actin patches was similar to that of the newly synthesized cell wall materials, as shown by confocal laser scanning microscopy (CLSM). In serial sectioned TEM images, filasomes were spherical, 100-300 nm in diameter and consisted of a single microvesicle (35-70 nm diameter) surrounded by fine filaments. Filasomes were adjacent to the newly formed glucan fibrils in single, cluster or rosary forms. By IEM analysis, we found that colloidal gold particles indicating actin molecules were present in the filamentous area of filasomes. Three-dimensional reconstruction images of serial sections clarified that the distribution of filasomes corresponded to the distribution of F-actin patches revealed by CLSM. Thus, a filasome is one of the F-actin patch structures appearing in the cytoplasm at the site of the initial formation of the cell wall and it may play an important role in this action.

  15. Reduced expression of citrate synthase leads to excessive superoxide formation and cell apoptosis.

    PubMed

    Cai, Quanxiang; Zhao, Mengmeng; Liu, Xiang; Wang, Xiaochun; Nie, Yao; Li, Ping; Liu, Tingyan; Ge, Ruli; Han, Fengchan

    2017-02-16

    A/J mice are a mouse model of age-related hearing loss. It has been demonstrated that a mutation in gene of citrate synthase (CS) contributes to the early onset of hearing loss occurring at about one month of age. To understand the effects of a decreased CS activity that results from the mutation in Cs gene on hearing loss in A/J mice, human kidney cell line (293T) was transiently transfected with short hairpin RNA for Cs (shRNA-Cs) to reduce expression of CS. In comparison with those of cells transfected with a scrambled sequence (shRNA-NC), the oxygen consumption rate and adenosine trisphosphate (ATP) production level were decreased in 293T cells transfected with shRNA-Cs. Meanwhile, excessive superoxide production was induced as determined by mitochondrial superoxide formation assay (MitoSOX) and superoxide dismutase 2 (SOD2) detection. Moreover, the expression levels of BIP (binding immunoglobulin protein) and CHOP (CCAAT/enhancer-binding protein-homologous protein), markers of endoplasmic reticulum stress, were upregulated. Furthermore, apoptosis related molecule caspase-3 and the mitochondrial membrane potential were reduced. It is therefore concluded that downregulation of Cs expression in 293T cells leads to low level of ATP production, excessive superoxide formation and cell apoptosis, which implies a possible mechanism for hearing loss in A/J mice.

  16. The plant cell cycle: Pre-Replication complex formation and controls.

    PubMed

    Brasil, Juliana Nogueira; Costa, Carinne N Monteiro; Cabral, Luiz Mors; Ferreira, Paulo C G; Hemerly, Adriana S

    2017-03-16

    The multiplication of cells in all living organisms requires a tight regulation of DNA replication. Several mechanisms take place to ensure that the DNA is replicated faithfully and just once per cell cycle in order to originate through mitoses two new daughter cells that contain exactly the same information from the previous one. A key control mechanism that occurs before cells enter S phase is the formation of a pre-replication complex (pre-RC) that is assembled at replication origins by the sequential association of the origin recognition complex, followed by Cdt1, Cdc6 and finally MCMs, licensing DNA to start replication. The identification of pre-RC members in all animal and plant species shows that this complex is conserved in eukaryotes and, more importantly, the differences between kingdoms might reflect their divergence in strategies on cell cycle regulation, as it must be integrated and adapted to the niche, ecosystem, and the organism peculiarities. Here, we provide an overview of the knowledge generated so far on the formation and the developmental controls of the pre-RC mechanism in plants, analyzing some particular aspects in comparison to other eukaryotes.

  17. INF2 promotes the formation of detyrosinated microtubules necessary for centrosome reorientation in T cells

    PubMed Central

    Andrés-Delgado, Laura; Antón, Olga M.; Bartolini, Francesca; Ruiz-Sáenz, Ana; Correas, Isabel; Gundersen, Gregg G.

    2012-01-01

    T cell antigen receptor–proximal signaling components, Rho-family GTPases, and formin proteins DIA1 and FMNL1 have been implicated in centrosome reorientation to the immunological synapse of T lymphocytes. However, the role of these molecules in the reorientation process is not yet defined. Here we find that a subset of microtubules became rapidly stabilized and that their α-tubulin subunit posttranslationally detyrosinated after engagement of the T cell receptor. Formation of stabilized, detyrosinated microtubules required the formin INF2, which was also found to be essential for centrosome reorientation, but it occurred independently of T cell receptor–induced massive tyrosine phosphorylation. The FH2 domain, which was mapped as the INF2 region involved in centrosome repositioning, was able to mediate the formation of stable, detyrosinated microtubules and to restore centrosome translocation in DIA1-, FMNL1-, Rac1-, and Cdc42-deficient cells. Further experiments indicated that microtubule stabilization was required for centrosome polarization. Our work identifies INF2 and stable, detyrosinated microtubules as central players in centrosome reorientation in T cells. PMID:22986496

  18. Zinc as a Signal to Stimulate Red Blood Cell Formation in Fish

    PubMed Central

    Chen, Yen-Hua; Shiu, Jhe-Ruei; Ho, Chia-Ling; Jeng, Sen-Shyong

    2017-01-01

    The common carp can tolerate extremely low oxygen levels. These fish store zinc in a specific zinc-binding protein presented in digestive tract tissues, and under low oxygen, the stored zinc is released and used as a signal to stimulate erythropoiesis (red blood cell formation). To determine whether the environmental supply of zinc to other fish species can serve as a signal to induce erythropoiesis as in the common carp, head kidney cells of four different fish species were cultured with supplemental ZnCl2. Zinc stimulated approximately a three-fold increase in immature red blood cells (RBCs) in one day. The stimulation of erythropoiesis by zinc was dose-dependent. ZnSO4 solution was injected into an experimental blood loss tilapia model. Blood analysis and microscopic observation of the blood cells indicated that, in vivo, the presence of additional zinc induced erythropoiesis in the bled tilapia. In the fish species studied, zinc could be used as a signal to stimulate erythropoiesis both in vitro and in vivo. The present report suggests a possible approach for the induction of red blood cell formation in animals through the supply of a certain level of zinc through either diet or injection. PMID:28085070

  19. Brassinosteroid signaling directs formative cell divisions and protophloem differentiation in Arabidopsis root meristems.

    PubMed

    Kang, Yeon Hee; Breda, Alice; Hardtke, Christian S

    2017-01-15

    Brassinosteroids (BRs) trigger an intracellular signaling cascade through its receptors BR INSENSITIVE 1 (BRI1), BRI1-LIKE 1 (BRL1) and BRL3. Recent studies suggest that BR-independent inputs related to vascular differentiation, for instance root protophloem development, modulate downstream BR signaling components. Here, we report that protophloem sieve element differentiation is indeed impaired in bri1 brl1 brl3 mutants, although this effect might not be mediated by canonical downstream BR signaling components. We also found that their small meristem size is entirely explained by reduced cell elongation, which is, however, accompanied by supernumerary formative cell divisions in the radial dimension. Thus, reduced cell expansion in conjunction with growth retardation, because of the need to accommodate supernumerary formative divisions, can account for the overall short root phenotype of BR signaling mutants. Tissue-specific re-addition of BRI1 activity partially rescued subsets of these defects through partly cell-autonomous, partly non-cell-autonomous effects. However, protophloem-specific BRI1 expression essentially rescued all major bri1 brl1 brl3 root meristem phenotypes. Our data suggest that BR perception in the protophloem is sufficient to systemically convey BR action in the root meristem context.

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

    PubMed

    Walcott, Sam; Sun, Sean X

    2010-04-27

    Tissue cells sense and respond to t