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Sample records for assay single cell

  1. Single-cell nanotoxicity assays of superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Eustaquio, Trisha; Leary, James F

    2012-01-01

    Properly evaluating the nanotoxicity of nanoparticles involves much more than bulk-cell assays of cell death by necrosis. Cells exposed to nanoparticles may undergo repairable oxidative stress and DNA damage or be induced into apoptosis. Exposure to nanoparticles may cause the cells to alter their proliferation or differentiation or their cell-cell signaling with neighboring cells in a tissue. Nanoparticles are usually more toxic to some cell subpopulations than others, and toxicity often varies with cell cycle. All of these facts dictate that any nanotoxicity assay must be at the single-cell level and must try whenever feasible and reasonable to include many of these other factors. Focusing on one type of quantitative measure of nanotoxicity, we describe flow and scanning image cytometry approaches to measuring nanotoxicity at the single-cell level by using a commonly used assay for distinguishing between necrotic and apoptotic causes of cell death by one type of nanoparticle. Flow cytometry is fast and quantitative, provided that the cells can be prepared into a single-cell suspension for analysis. But when cells cannot be put into suspension without altering nanotoxicity results, or if morphology, attachment, and stain location are important, a scanning image cytometry approach must be used. Both methods are described with application to a particular type of nanoparticle, a superparamagnetic iron oxide nanoparticle (SPION), as an example of how these assays may be applied to the more general problem of determining the effects of nanomaterial exposure to living cells.

  2. The single-cell gel electrophoresis assay to determine apoptosis ...

    African Journals Online (AJOL)

    The aim of the present study was to determine if the pattern of DNA fragmentation determined by the single cell gel electrophoresis assay can be used to determine apoptosis induced by siRNA in Colo 320 cells. When the frequency of appearance of apoptotic cells following was observed over a period of time, there was a ...

  3. Single Cell Adhesion Assay Using Computer Controlled Micropipette

    Science.gov (United States)

    Salánki, Rita; Hős, Csaba; Orgovan, Norbert; Péter, Beatrix; Sándor, Noémi; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabó, Bálint

    2014-01-01

    Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today’s techniques typically have an extremely low throughput (5–10 cells per day). Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (∼30 min). We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a sub

  4. Single cell adhesion assay using computer controlled micropipette.

    Directory of Open Access Journals (Sweden)

    Rita Salánki

    Full Text Available Cell adhesion is a fundamental phenomenon vital for all multicellular organisms. Recognition of and adhesion to specific macromolecules is a crucial task of leukocytes to initiate the immune response. To gain statistically reliable information of cell adhesion, large numbers of cells should be measured. However, direct measurement of the adhesion force of single cells is still challenging and today's techniques typically have an extremely low throughput (5-10 cells per day. Here, we introduce a computer controlled micropipette mounted onto a normal inverted microscope for probing single cell interactions with specific macromolecules. We calculated the estimated hydrodynamic lifting force acting on target cells by the numerical simulation of the flow at the micropipette tip. The adhesion force of surface attached cells could be accurately probed by repeating the pick-up process with increasing vacuum applied in the pipette positioned above the cell under investigation. Using the introduced methodology hundreds of cells adhered to specific macromolecules were measured one by one in a relatively short period of time (∼30 min. We blocked nonspecific cell adhesion by the protein non-adhesive PLL-g-PEG polymer. We found that human primary monocytes are less adherent to fibrinogen than their in vitro differentiated descendants: macrophages and dendritic cells, the latter producing the highest average adhesion force. Validation of the here introduced method was achieved by the hydrostatic step-pressure micropipette manipulation technique. Additionally the result was reinforced in standard microfluidic shear stress channels. Nevertheless, automated micropipette gave higher sensitivity and less side-effect than the shear stress channel. Using our technique, the probed single cells can be easily picked up and further investigated by other techniques; a definite advantage of the computer controlled micropipette. Our experiments revealed the existence of a

  5. The Single Prostate Cell Transcriptome as Biological Assay

    National Research Council Canada - National Science Library

    Nelson, Peter

    1999-01-01

    .... The scope to the research involves the construction of cDNA libraries representing the genes expressed in selected populations of normal and neoplastic prostate cancer cells followed by the construction of microarrays suitable for comprehensive gene expression studies. These arrays are then used to evaluate methods for single-cell transcriptome amplification with the aim of identifying a cohort of cellular transcripts which correlate with, or.

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

    Directory of Open Access Journals (Sweden)

    Yomo Tetsuya

    2006-06-01

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

  7. Measurement of separase proteolytic activity in single living cells by a fluorogenic flow cytometry assay.

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    Wiltrud Haaß

    Full Text Available ESPL1/Separase, an endopeptidase, is required for centrosome duplication and separation of sister-chromatides in anaphase of mitosis. Overexpression and deregulated proteolytic activity of Separase as frequently observed in human cancers is associated with the occurrence of supernumerary centrosomes, chromosomal missegregation and aneuploidy. Recently, we have hypothesized that increased Separase proteolytic activity in a small subpopulation of tumor cells may serve as driver of tumor heterogeneity and clonal evolution in chronic myeloid leukemia (CML. Currently, there is no quantitative assay to measure Separase activity levels in single cells. Therefore, we have designed a flow cytometry-based assay that utilizes a Cy5- and rhodamine 110 (Rh110-biconjugated Rad21 cleavage site peptide ([Cy5-D-R-E-I-M-R]2-Rh110 as smart probe and intracellular substrate for detection of Separase enzyme activity in living cells. As measured by Cy5 fluorescence the cellular uptake of the fluorogenic peptide was fast and reached saturation after 210 min of incubation in human histiocytic lymphoma U937 cells. Separase activity was recorded as the intensity of Rh110 fluorescence released after intracellular peptide cleavage providing a linear signal gain within a 90-180 min time slot. Compared to conventional cell extract-based methods the flow cytometric assay delivers equivalent results but is more reliable, bypasses the problem of vague loading controls and unspecific proteolysis associated with whole cell extracts. Especially suited for the investigaton of blood- and bone marrow-derived hematopoietic cells the flow cytometric Separase assay allows generation of Separase activity profiles that tell about the number of Separase positive cells within a sample i.e. cells that currently progress through mitosis and about the range of intercellular variation in Separase activity levels within a cell population. The assay was used to quantify Separase proteolytic

  8. Application of the Single Cell Gel Electrophoresis (SCGE) Assay to Genotoxicity Evaluation in Plants and Animals

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Kyu

    2007-10-15

    Application of the Single Cell Gel Electrophoresis (SCGE) Assay to Genotoxicity Evaluation in Plants and Animals. Recently, the importance of ionizing radiation and chemicals has been recognized since radio- and chemical therapy is directly related to the control of various diseases such as cancer. Radiation and the chemicals can cause biological damages while they have great applicability. It is of necessity to analyze rapidly, easily and accurately the biological effects, especially DNA damage due to those factors. Recently SCGE (single cell gel electrophoresis assay, alias comet assay) has been developed for the efficient evaluation of DNA damage. In this report, the comprehensive review will be given on the rationale, the technical applications and the advantages and shortcomings of SCGE assay. This method can be directly applied to study on toxicity, cancer, and aging in terms of the evaluation of DNA damages due to radiation and chemicals on human cellular level. It is also suggested that comet assay be used for testing genotoxicity of suspected substances, detecting irradiated foods, screening radioprotective candidates, and studying DNA repair process in various biological systems.

  9. Improved single-cell gel electrophoresis assay for detecting DNA damage in Eisenia foetida.

    Science.gov (United States)

    Di Marzio, Walter D; Saenz, María E; Lemière, Sebastien; Vasseur, Paule

    2005-12-01

    The earthworm (Eisenia foetida) is an attractive sentinel species for detecting genotoxicity in soil. In this study, an improved single-cell gel electrophoresis (SCGE) assay was developed for detecting DNA damage in the coelomocytes (lymphocytes) of earthworms. Coelomocytes were obtained from the coelomic fluid using a modified extrusion medium that did not include the mucolytic agent guaiacol. The extruded coelomocytes contained at least three types of cells: eleocytes (75% of the total), amoebocytes, and granulocytes. The DNA migration parameters were determined for untreated cells of each type in order that the assay could be performed with minimum inter- and intra-individual variation. In addition, lysis time was reduced to 10 min, and only one neutralization step was used. DNA damage was detected in isolated eleocytes treated with hydrogen peroxide and cadmium, and in eleocytes from earthworms exposed for up to 21 days to soil containing polycyclic aromatic hydrocarbons. The SCGE assay using earthworm eleocytes appears to be a sensitive biomarker for evaluating exposure to genotoxic compounds.

  10. Evaluation of digital real-time PCR assay as a molecular diagnostic tool for single-cell analysis.

    Science.gov (United States)

    Chang, Chia-Hao; Mau-Hsu, Daxen; Chen, Ke-Cheng; Wei, Cheng-Wey; Chiu, Chiung-Ying; Young, Tai-Horng

    2018-02-21

    In a single-cell study, isolating and identifying single cells are essential, but these processes often require a large investment of time or money. The aim of this study was to isolate and analyse single cells using a novel platform, the PanelChip™ Analysis System, which includes 2500 microwells chip and a digital real-time polymerase chain reaction (dqPCR) assay, in comparison with a standard PCR (qPCR) assay. Through the serial dilution of a known concentration standard, namely pUC19, the accuracy and sensitivity levels of two methodologies were compared. The two systems were tested on the basis of expression levels of the genetic markers vimentin, E-cadherin, N-cadherin and GAPDH in A549 lung carcinoma cells at two known concentrations. Furthermore, the influence of a known PCR inhibitor commonly found in blood samples, heparin, was evaluated in both methodologies. Finally, mathematical models were proposed and separation method of single cells was verified; moreover, gene expression levels during epithelial-mesenchymal transition in single cells under TGFβ1 treatment were measured. The drawn conclusion is that dqPCR performed using PanelChip™ is superior to the standard qPCR in terms of sensitivity, precision, and heparin tolerance. The dqPCR assay is a potential tool for clinical diagnosis and single-cell applications.

  11. High-throughput Characterization of HIV-1 Reservoir Reactivation Using a Single-Cell-in-Droplet PCR Assay

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    Robert W. Yucha

    2017-06-01

    Full Text Available Reactivation of latent viral reservoirs is on the forefront of HIV-1 eradication research. However, it is unknown if latency reversing agents (LRAs increase the level of viral transcription from cells producing HIV RNA or harboring transcriptionally-inactive (latent infection. We therefore developed a microfluidic single-cell-in-droplet (scdPCR assay to directly measure the number of CD4+ T cells that produce unspliced (usRNA and multiply spliced (msRNA following ex vivo latency reversal with either an histone deacetylase inhibitor (romidepsin or T cell receptor (TCR stimulation. Detection of HIV-1 transcriptional activity can also be performed on hundreds of thousands of CD4+ T-cells in a single experiment. The scdPCR method was then applied to CD4+ T cells obtained from HIV-1-infected individuals on antiretroviral therapy. Overall, our results suggest that effects of LRAs on HIV-1 reactivation may be heterogeneous—increasing transcription from active cells in some cases and increasing the number of transcriptionally active cells in others. Genomic DNA and human mRNA isolated from HIV-1 reactivated cells could also be detected and quantified from individual cells. As a result, our assay has the potential to provide needed insight into various reservoir eradication strategies.

  12. High-throughput Characterization of HIV-1 Reservoir Reactivation Using a Single-Cell-in-Droplet PCR Assay.

    Science.gov (United States)

    Yucha, Robert W; Hobbs, Kristen S; Hanhauser, Emily; Hogan, Louise E; Nieves, Wildaliz; Ozen, Mehmet O; Inci, Fatih; York, Vanessa; Gibson, Erica A; Thanh, Cassandra; Shafiee, Hadi; El Assal, Rami; Kiselinova, Maja; Robles, Yvonne P; Bae, Helen; Leadabrand, Kaitlyn S; Wang, ShuQi; Deeks, Steven G; Kuritzkes, Daniel R; Demirci, Utkan; Henrich, Timothy J

    2017-06-01

    Reactivation of latent viral reservoirs is on the forefront of HIV-1 eradication research. However, it is unknown if latency reversing agents (LRAs) increase the level of viral transcription from cells producing HIV RNA or harboring transcriptionally-inactive (latent) infection. We therefore developed a microfluidic single-cell-in-droplet (scd)PCR assay to directly measure the number of CD4 + T cells that produce unspliced (us)RNA and multiply spliced (ms)RNA following ex vivo latency reversal with either an histone deacetylase inhibitor (romidepsin) or T cell receptor (TCR) stimulation. Detection of HIV-1 transcriptional activity can also be performed on hundreds of thousands of CD4+ T-cells in a single experiment. The scdPCR method was then applied to CD4 + T cells obtained from HIV-1-infected individuals on antiretroviral therapy. Overall, our results suggest that effects of LRAs on HIV-1 reactivation may be heterogeneous-increasing transcription from active cells in some cases and increasing the number of transcriptionally active cells in others. Genomic DNA and human mRNA isolated from HIV-1 reactivated cells could also be detected and quantified from individual cells. As a result, our assay has the potential to provide needed insight into various reservoir eradication strategies. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Kinetic Modeling of ABCG2 Transporter Heterogeneity: A Quantitative, Single-Cell Analysis of the Side Population Assay.

    Directory of Open Access Journals (Sweden)

    Adam F Prasanphanich

    2016-11-01

    Full Text Available The side population (SP assay, a technique used in cancer and stem cell research, assesses the activity of ABC transporters on Hoechst staining in the presence and absence of transporter inhibition, identifying SP and non-SP cell (NSP subpopulations by differential staining intensity. The interpretation of the assay is complicated because the transporter-mediated mechanisms fail to account for cell-to-cell variability within a population or adequately control the direct role of transporter activity on staining intensity. We hypothesized that differences in dye kinetics at the single-cell level, such as ABCG2 transporter-mediated efflux and DNA binding, are responsible for the differential cell staining that demarcates SP/NSP identity. We report changes in A549 phenotype during time in culture and with TGFβ treatment that correlate with SP size. Clonal expansion of individually sorted cells re-established both SP and NSPs, indicating that SP membership is dynamic. To assess the validity of a purely kinetics-based interpretation of SP/NSP identity, we developed a computational approach that simulated cell staining within a heterogeneous cell population; this exercise allowed for the direct inference of the role of transporter activity and inhibition on cell staining. Our simulated SP assay yielded appropriate SP responses for kinetic scenarios in which high transporter activity existed in a portion of the cells and little differential staining occurred in the majority of the population. With our approach for single-cell analysis, we observed SP and NSP cells at both ends of a transporter activity continuum, demonstrating that features of transporter activity as well as DNA content are determinants of SP/NSP identity.

  14. Kinetic Modeling of ABCG2 Transporter Heterogeneity: A Quantitative, Single-Cell Analysis of the Side Population Assay

    Science.gov (United States)

    Prasanphanich, Adam F.; White, Douglas E.; Gran, Margaret A.

    2016-01-01

    The side population (SP) assay, a technique used in cancer and stem cell research, assesses the activity of ABC transporters on Hoechst staining in the presence and absence of transporter inhibition, identifying SP and non-SP cell (NSP) subpopulations by differential staining intensity. The interpretation of the assay is complicated because the transporter-mediated mechanisms fail to account for cell-to-cell variability within a population or adequately control the direct role of transporter activity on staining intensity. We hypothesized that differences in dye kinetics at the single-cell level, such as ABCG2 transporter-mediated efflux and DNA binding, are responsible for the differential cell staining that demarcates SP/NSP identity. We report changes in A549 phenotype during time in culture and with TGFβ treatment that correlate with SP size. Clonal expansion of individually sorted cells re-established both SP and NSPs, indicating that SP membership is dynamic. To assess the validity of a purely kinetics-based interpretation of SP/NSP identity, we developed a computational approach that simulated cell staining within a heterogeneous cell population; this exercise allowed for the direct inference of the role of transporter activity and inhibition on cell staining. Our simulated SP assay yielded appropriate SP responses for kinetic scenarios in which high transporter activity existed in a portion of the cells and little differential staining occurred in the majority of the population. With our approach for single-cell analysis, we observed SP and NSP cells at both ends of a transporter activity continuum, demonstrating that features of transporter activity as well as DNA content are determinants of SP/NSP identity. PMID:27851764

  15. Viable human buccal mucosa cells do not yield typical nucleoids: impacts on the single-cell gel electrophoresis/Comet assay.

    Science.gov (United States)

    Pinhal, Danillo; Gontijo, Alisson Marques de Miranda Cabral; Reyes, Victor Alexis Valenzuela; Salvadori, Daisy Maria Favero

    2006-03-01

    Buccal mucosa (BM) cells have been used in human biomonitoring studies for detecting DNA adducts and chromosomal damage in an epithelial cell population. In the present study, we have investigated if human BM cells are suitable for use in the single-cell gel electrophoresis (SCGE)/Comet assay as an approach for estimating the exposure of epithelial cells to DNA-damaging agents. Our results indicate that only a few cells from BM cell samples yield comets that can be analyzed by current methods, and that the yield of cells with comets is independent of the percentage of viable BM cells in the sample. Data generated after enzymatic enrichment of viable cells and immunomagnetic separation of epithelial cells suggest that most of the BM cells that do form comets are probably leukocytes. Moreover, by reevaluating specific cells after running the Comet assay, we found that viable epithelial BM cells give rise to atypical comets that are not included in the analysis. Comparing DNA migration patterns between small groups of smokers and nonsmokers indicated that long-term smoking had no effect on the subpopulation of cells that yield typical comets. Our results indicate that the SCGE assay, as it is commonly performed, may not be useful for genotoxicity monitoring in human epithelial BM cells. (c) 2005 Wiley-Liss, Inc.

  16. Using a medium-throughput comet assay to evaluate the global DNA methylation status of single cells

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    Angelique eLewies

    2014-07-01

    Full Text Available The comet assay is a simple and cost effective technique, commonly used to analyse and quantify DNA damage in individual cells. The versatility of the comet assay allows introduction of various modifications to the basic technique. The difference in the methylation sensitivity of the isoschizomeric restriction enzymes HpaII and MspI are used to demonstrate the ability of the comet assay to measure the global DNA methylation level of individual cells when using cell cultures. In the experiments described here, a medium-throughput comet assay and methylation sensitive comet assay are combined to produce a methylation sensitive medium-throughput comet assay to measure changes in the global DNA methylation pattern in individual cells under various growth conditions.

  17. In vitro genotoxic effects of hard metal particles assessed by alkaline single cell gel and elution assays.

    Science.gov (United States)

    Anard, D; Kirsch-Volders, M; Elhajouji, A; Belpaeme, K; Lison, D

    1997-01-01

    Hard metals (WC-Co) are made of a mixture of cobalt metal (Co, 5-10%) and tungsten carbide particles (WC, >80%). Excessive inhalation of WC-Co is associated with the occurrence of different lung diseases including an excess of lung cancers. The elective toxicity of hard metal is based on a physico-chemical interaction between cobalt metal and tungsten carbide particles to produce activated oxygen species. The aim of the present study was to assess the genotoxic activity of hard metal particles as compared with Co and WC alone. In human peripheral lymphocytes incubated with Co or WC-Co, a dose- and time-dependent increased production of DNA single strand breaks (ssb) was evidenced by alkaline single cell gel electrophoresis (SCGE) and modified alkaline elution (AE) assays. Addition of 1 M formate, a hydroxyl radical scavenger, had a protective effect against the production of ssb by both WC-Co or Co alone. On the basis of an equivalent cobalt-content, WC-Co produced significantly more ssb than Co. WC alone did not produce DNA ssb detectable by the AE assay, but results obtained with the SCGE assay may suggest that it either allows some uncoiling of the chromatin loops or induces the formation of slowly migrating fragments. Overall, this in vitro study is the first demonstration of the clastogenic property of cobalt metal-containing dusts. The results are consistent with the implication of an increased production of hydroxyl radicals when Co is mixed with WC particles. The SCGE results also suggest that WC may modify the structure of the chromatin, leading to an increased DNA sensitivity to clastogenic effects. Both mechanisms are not mutually exclusive and may concurrently contribute to the greater clastogenic activity of WC-Co dust. This property of WC-Co particles may account for the excess of lung cancers observed in hard metal workers.

  18. Quantitative assay of element mass inventories in single cell biological systems with micro-PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Ogrinc, Nina [Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); LOTRIČ Metrology, Selca 163, SI-4227 Selca (Slovenia); Pelicon, Primož, E-mail: primoz.pelicon@ijs.si [Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Vavpetič, Primož; Kelemen, Mitja; Grlj, Nataša; Jeromel, Luka [Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Tomić, Sergej [Medical Faculty of the Military Medical Academy, University of Defense, Crnotravska 17, Belgrade (Serbia); Čolić, Miodrag [Medical Faculty of the Military Medical Academy, University of Defense, Crnotravska 17, Belgrade (Serbia); Medical Faculty, University of Niš, Boulevard of Dr. Zoran Djindjić 81, 18000 Niš (Serbia); Beran, Alfred [Dipartimento di Oceanografia Biologica, Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Via Auguste Piccard 54, 34151 Trieste (Italy)

    2013-07-01

    Elemental concentrations in micro-PIXE (Particle Induced X-ray Emission) maps of elements in biological tissue slices have been determined using auxiliary information on the sample matrix composition from EBS (Elastic Backscattering Spectroscopy) and STIM (Scanning Transmission Ion Microscopy). The thin sample approximation may be used for evaluating micro-PIXE data in cases, where X-ray absorption in the sample can be neglected and the mass of elements in a selected area can be estimated. The resulting sensitivity amounts to an impressive 10{sup −12} g of the selected elements. Two cases are presented as examples. In the first, we determined the total mass of gold nanoparticles internalized by human monocyte-derived dendritic cells (MDDC). In the second, an inventory of the mass of elements in the micro-particulate material adsorbed at the wall of the lorica of the microzooplankton species Tintinnopsis radix has been created.

  19. Quantitative assay of element mass inventories in single cell biological systems with micro-PIXE

    Science.gov (United States)

    Ogrinc, Nina; Pelicon, Primož; Vavpetič, Primož; Kelemen, Mitja; Grlj, Nataša; Jeromel, Luka; Tomić, Sergej; Čolić, Miodrag; Beran, Alfred

    2013-07-01

    Elemental concentrations in micro-PIXE (Particle Induced X-ray Emission) maps of elements in biological tissue slices have been determined using auxiliary information on the sample matrix composition from EBS (Elastic Backscattering Spectroscopy) and STIM (Scanning Transmission Ion Microscopy). The thin sample approximation may be used for evaluating micro-PIXE data in cases, where X-ray absorption in the sample can be neglected and the mass of elements in a selected area can be estimated. The resulting sensitivity amounts to an impressive 10-12 g of the selected elements. Two cases are presented as examples. In the first, we determined the total mass of gold nanoparticles internalized by human monocyte-derived dendritic cells (MDDC). In the second, an inventory of the mass of elements in the micro-particulate material adsorbed at the wall of the lorica of the microzooplankton species Tintinnopsis radix has been created.

  20. Immobilisation of barley aleurone layers enables parallelisation of assays and analysis of transient gene expression in single cells

    DEFF Research Database (Denmark)

    Zor, Kinga; Mark, Christina; Heiskanen, Arto

    2017-01-01

    The barley aleurone layer is an established model system for studying phytohormone signalling, enzyme secretion and programmed cell death during seed germination. Most analyses performed on the aleurone layer are end-point assays based on cell extracts, meaning each sample is only analysed at a s...

  1. Reversible G Protein βγ9 Distribution-Based Assay Reveals Molecular Underpinnings in Subcellular, Single-Cell, and Multicellular GPCR and G Protein Activity.

    Science.gov (United States)

    Senarath, Kanishka; Ratnayake, Kasun; Siripurapu, Praneeth; Payton, John L; Karunarathne, Ajith

    2016-12-06

    Current assays to measure the activation of G protein coupled receptors (GPCRs) and G proteins are time-consuming, indirect, and expensive. Therefore, an efficient method which directly measures the ability of a ligand to govern GPCR-G protein interactions can help to understand the molecular underpinnings of the associated signaling. A live cell imaging-based approach is presented here to directly measure ligand-induced GPCR and G protein activity in real time. The number of active GPCRs governs G protein heterotrimer (αβγ) dissociation, thereby controlling the concentration of free βγ subunits. The described γ9 assay measures the GPCR activation-induced extent of the reversible βγ9 subunit exchange between the plasma membrane (PM) and internal membranes (IMs). Confocal microscopy-based γ9 assay quantitatively determines the concentration dependency of ligands on GPCR activation. Demonstrating the high-throughput screening (HTS) adaptability, the γ9 assay performed using an imaging plate reader measures the ligand-induced GPCR activation. This suggests that the γ9 assay can be employed to screen libraries of compounds for their ability to activate GPCRs. Together with subcellular optogenetics, the spatiotemporal sensitivity of the γ9 assay permits experimental determination of the limits of spatially restricted activation of GPCRs and G proteins in subcellular regions of single cells. This assay works effectively for GPCRs coupled to αi/o and αs heterotrimers, including light-sensitive GPCRs. In addition, computational modeling of experimental data from the assay is used to decipher intricate molecular details of the GPCR-G protein activation process. Overall, the γ9 assay provides a robust strategy for quantitative as well as qualitative determination of GPCR and G protein function on a single-cell, multicell, and subcellular level. This assay not only provides information about the inner workings of the signaling pathway, but it also strengthens

  2. Serial Measurements of Apoptotic Cell Numbers Provide Better Acceptance Criterion for PBMC Quality than a Single Measurement Prior to the T Cell Assay

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    Marie Wunsch

    2015-01-01

    Full Text Available As soon as Peripheral Blood Mononuclear Cells (PBMC are isolated from whole blood, some cells begin dying. The rate of apoptotic cell death is increased when PBMC are shipped, cryopreserved, or stored under suboptimal conditions. Apoptotic cells secrete cytokines that suppress inflammation while promoting phagocytosis. Increased numbers of apoptotic cells in PBMC may modulate T cell functions in antigen-triggered T cell assays. We assessed the effect of apoptotic bystander cells on a T cell ELISPOT assay by selectively inducing B cell apoptosis using α-CD20 mAbs. The presence of large numbers of apoptotic B cells did not affect T cell functionality. In contrast, when PBMC were stored under unfavorable conditions, leading to damage and apoptosis in the T cells as well as bystander cells, T cell functionality was greatly impaired. We observed that measuring the number of apoptotic cells before plating the PBMC into an ELISPOT assay did not reflect the extent of PBMC injury, but measuring apoptotic cell frequencies at the end of the assay did. Our data suggest that measuring the numbers of apoptotic cells prior to and post T cell assays may provide more stringent PBMC quality acceptance criteria than measurements done only prior to the start of the assay.

  3. Real-time PCR with molecular beacons provides a highly accurate assay for detection of Tay-Sachs alleles in single cells.

    Science.gov (United States)

    Rice, John E; Sanchez, J Aquiles; Pierce, Kenneth E; Wangh, Lawrence J

    2002-12-01

    The results presented here provide the first single-cell genetic assay for Tay-Sachs disease based on real-time PCR. Individual lymphoblasts were lysed with an optimized lysis buffer and assayed using one pair of primers that amplifies both the wild type and 1278 + TATC Tay-Sachs alleles. The resulting amplicons were detected in real time with two molecular beacons each with a different colored fluorochrome. The kinetics of amplicon accumulation generate objective criteria by which to evaluate the validity of each reaction. The assay had an overall utility of 95%, based on the detection of at least one signal in 235 of the 248 attempted tests and an efficiency of 97%, as 7 of the 235 samples were excluded from further analysis for objective quantitative reasons. The accuracy of the assay was 99.1%, because 228 of 230 samples gave signals consistent with the genotype of the cells. Only two of the 135 heterozygous samples were allele drop-outs, a rate far lower than previously reported for single-cell Tay-Sachs assays using conventional methods of PCR. Copyright 2002 John Wiley & Sons, Ltd.

  4. The application of single cell gel electrophoresis or comet assay to human monitoring studies Aplicacion de la electroforesis unicelular o ensayo cometa en estudios de monitoreo humano

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    Mahara Valverde

    1999-11-01

    Full Text Available Objective. In the search of new human genotoxic biomarkers, the single cell gel electrophoresis assay has been proposed as a sensible alternative. Material and methods. This technique detects principally single strand breaks as well as alkali-labile and repair-retarded sites. Results. Herein we present our experience using the single cell gel electrophoresis assay in human population studies, both occupationally and environmentally exposed. Conclusions. We discuss the assay feasibility as a genotoxic biomarker.Objetivo. En la búsqueda de nuevos marcadores genotóxicos aplicables a estudios de poblaciones humanas expuestos a xenobióticos, la utilización del ensayo de electroforesis en una sola célula se ha propuesto como un método sensible y una buena alternativa. Material y métodos. Esta técnica detecta rompimientos en el ADN de cadena sencilla, así como sitios álcali lábiles y sitios retardados de reparación. Resultados. En este trabajo, presentamos nuestra experiencia utilizando este ensayo en poblaciones humanas expuestas ocupacionalmente o ambientalmente a diferentes xenobióticos. Conclusiones. Se discute la posible utilidad de este ensayo como un biomarcador de efecto genotóxico.

  5. Evaluation of radio-induced DNA damage and their repair in human lymphocytes by comet assay or single cell gel electrophoresis

    International Nuclear Information System (INIS)

    Nascimento, Patricia A. do; Suzuki, Miriam F.; Okazaki, Kayo

    1997-01-01

    The comet assay, also called single cell gel electrophoresis technique, permits to evaluate quantitatively DNA breakage induced by chemical and physical agents at the level of the single cell. The present paper refers to the construction of dose-response curves to DNA damage and repair studies in human peripheral lymphocytes, utilizing the comet assay for the radiosensitivity analysis. So, the blood samples were obtained from healthy donors (40-50 year old), irradiated in a 60 Co source (GAMMACEL 220) with doses of 0.17, 0.25, 0.57, 1.10, 2.12 and 4.22 Gy (0.59 Gy/min.) and processed 1 and 24 hours after the exposition. Results obtained showed a increase in the total lenght of comet (DNA migration) as a function of radiation dose in samples processed 1 and 24 hours after the treatment. The DNA lesion in irradiated lymphocytes with 4.22 Gy (means value of 101.4 μm) were 3.4 times higher than in the untreated lymphocytes (mean value of 30 μm) instead of 24 hours after the irradiation were 1.5 times higher (mean value of 46.3 μm). This reduction on DNA repair occurred in these cells. It was also possible visualized the presence of subpopulations of the cells with different sensitivity and repair capacity to ionizing radiation in these donors. (author). 8 refs., 3 figs

  6. Evaluation of genotoxicity after application of Listerine(R) on human lymphocytes by micronucleus and single cell gel electrophoresis assays.

    Science.gov (United States)

    Türkez, Hasan; Togar, Basak; Arabaci, Taner

    2012-04-01

    Listerine (LN) is one of the most commonly used mouth rinses worldwide although very limited information is available concerning its genotoxicity. In another view, the biological safety profile of oral care products is frequently assumed on the basis of simplistic test models. Therefore, the present study was undertaken to investigate the in vitro genotoxic potential of LN using micronucleus and single cell gel electrophoresis tests as genetic endpoints. Different concentrations of LN (0-100% of ml/culture, v/v) were applied to whole human blood cultures (n = 5). The result of the present study showed that there were no statistically significant differences (p > 0.05) between the control group and the groups treated with LN alone in both analysed endpoints. In conclusion, our result first demonstrated the absence of genotoxicity of LN on human lymphocytes.

  7. A Novel High-Content Immunofluorescence Assay as a Tool to Identify at the Single Cell Level γ-Globin Inducing Compounds.

    Directory of Open Access Journals (Sweden)

    Marta Durlak

    Full Text Available The identification of drugs capable of reactivating γ-globin to ameliorate β-thalassemia and Sickle Cell anemia is still a challenge, as available γ-globin inducers still have limited clinical indications. High-throughput screenings (HTS aimed to identify new potentially therapeutic drugs require suitable first-step-screening methods combining the possibility to detect variation in the γ/β globin ratio with the robustness of a cell line. We took advantage of a K562 cell line variant expressing β-globin (β-K562 to set up a new multiplexed high-content immunofluorescence assay for the quantification of γ- and β-globin content at single-cell level. The assay was validated by using the known globin inducers hemin, hydroxyurea and butyric acid and further tested in a pilot screening that confirmed HDACs as targets for γ-globin induction (as proved by siRNA-mediated HDAC3 knockdown and by treatment with HDACs inhibitors entinostat and dacinostat and identified Heme-oxygenases as novel candidate targets for γ-globin induction. Indeed, Heme-oxygenase2 siRNA knockdown as well as its inhibition by Tin protoporphyrin-IX (TinPPIX greatly increased γ-globin expression. This result is particularly interesting as several metalloporphyrins have already been developed for clinical uses and could be tested (alone or in combination with other drugs to improve pharmacological γ-globin reactivation for the treatment of β-hemoglobinopathies.

  8. Protective effects of Brussels sprouts towards B[a]P-induced DNA damage: a model study with the single-cell gel electrophpresis (SCGE)/Hep G2 assay

    NARCIS (Netherlands)

    Laky, B.; Knasmuller, S.; Gminski, R.; Mersch-Sundermann, V.; Scharf, G.; Verkerk, R.; Freywald, C.; Uhl, M.; Kassie, F.

    2002-01-01

    The aim of this study was to investigate the chemoprotective effects of Brussels sprouts juice towards benzo[a]pyrene (B(a)P)-induced DNA damage in the single-cell gel electrophoresis (SCGE)/Hep G2 test system. This assay combines the advantages of the SCGE assay with that of the use of

  9. Advantages of a single-cycle production assay to study cell culture-adaptive mutations of hepatitis C virus

    DEFF Research Database (Denmark)

    Russell, Rodney S; Meunier, Jean-Christophe; Takikawa, Shingo

    2008-01-01

    mutations that were selected during serial passage in Huh-7.5 cells were studied. Recombinant genomes containing all five mutations produced 3-4 logs more infectious virions than did wild type. Neither a coding mutation in NS5A nor a silent mutation in E2 was adaptive, whereas coding mutations in E2, p7......The JFH1 strain of hepatitis C virus (HCV) is unique among HCV isolates, in that the wild-type virus can traverse the entire replication cycle in cultured cells. However, without adaptive mutations, only low levels of infectious virus are produced. In the present study, the effects of five...

  10. Effect of Blood Collection Tube Type and Time to Processing on the Enumeration and High-Content Characterization of Circulating Tumor Cells Using the High-Definition Single-Cell Assay.

    Science.gov (United States)

    Rodríguez-Lee, Mariam; Kolatkar, Anand; McCormick, Madelyn; Dago, Angel D; Kendall, Jude; Carlsson, Nils Anders; Bethel, Kelly; Greenspan, Emily J; Hwang, Shelley E; Waitman, Kathryn R; Nieva, Jorge J; Hicks, James; Kuhn, Peter

    2018-02-01

    - As circulating tumor cell (CTC) assays gain clinical relevance, it is essential to address preanalytic variability and to develop standard operating procedures for sample handling in order to successfully implement genomically informed, precision health care. - To evaluate the effects of blood collection tube (BCT) type and time-to-assay (TTA) on the enumeration and high-content characterization of CTCs by using the high-definition single-cell assay (HD-SCA). - Blood samples of patients with early- and advanced-stage breast cancer were collected into cell-free DNA (CfDNA), EDTA, acid-citrate-dextrose solution, and heparin BCTs. Time-to-assay was evaluated at 24 and 72 hours, representing the fastest possible and more routine domestic shipping intervals, respectively. - We detected the highest CTC levels and the lowest levels of negative events in CfDNA BCT at 24 hours. At 72 hours in this BCT, all CTC subpopulations were decreased with the larger effect observed in high-definition CTCs and cytokeratin-positive cells smaller than white blood cells. Overall cell retention was also optimal in CfDNA BCT at 24 hours. Whole-genome copy number variation profiles were generated from single cells isolated from all BCT types and TTAs. Cells from CfDNA BCT at 24-hour TTA exhibited the least noise. - Circulating tumor cells can be identified and characterized under a variety of collection, handling, and processing conditions, but the highest quality can be achieved with optimized conditions. We quantified performance differences of the HD-SCA for specific preanalytic variables that may be used as a guide to develop best practices for implementation into patient care and/or research biorepository processes.

  11. Determination of cell survival after irradiation via clonogenic assay versus multiple MTT Assay - A comparative study

    International Nuclear Information System (INIS)

    Buch, Karl; Peters, Tanja; Nawroth, Thomas; Sänger, Markus; Schmidberger, Heinz; Langguth, Peter

    2012-01-01

    For studying proliferation and determination of survival of cancer cells after irradiation, the multiple MTT assay, based on the reduction of a yellow water soluble tetrazolium salt to a purple water insoluble formazan dye by living cells was modified from a single-point towards a proliferation assay. This assay can be performed with a large number of samples in short time using multi-well-plates, assays can be performed semi-automatically with a microplate reader. Survival, the calculated parameter in this assay, is determined mathematically. Exponential growth in both control and irradiated groups was proven as the underlying basis of the applicability of the multiple MTT assay. The equivalence to a clonogenic survival assay with its disadvantages such as time consumption was proven in two setups including plating of cells before and after irradiation. Three cell lines (A 549, LN 229 and F 98) were included in the experiment to study its principal and general applicability

  12. Kinetics of DNA strand breaks and protection by antioxidants in UVA- or UVB-irradiated HaCaT keratinocytes using the single cell gel electrophoresis assay.

    Science.gov (United States)

    Lehmann, J; Pollet, D; Peker, S; Steinkraus, V; Hoppe, U

    1998-03-01

    The aim of this study was to characterize the genotoxic action of UVA and UVB in human keratinocytes by application of the single cell gel electrophoresis assay (SCGE assay). Dose dependence of DNA damage, the time course of its repair, and the influence of cellular antioxidant status were assessed. Irradiation with UVA or UVB both resulted in a dose-dependent increase in the level of DNA damage. A time course study to evaluate the repair kinetics in keratinocytes irradiated with 5 J/cm2 UVA revealed an immediate occurrence of DNA effects which subsequently disappeared within about 1 h, indicating removal of DNA lesions. This rapid repair of DNA damage is consistent with the observation that 5 J/cm2 UVA did not impair cellular viability. In contrast, exposure to 15 mJ/cm2 UVB resulted in a prolonged repair of DNA damage which lasted about 25 h. Thus, the repair kinetics of UVA- and UVB-induced DNA damage clearly differed from each other, implicating the induction of different types of DNA lesions by UVA and UVB. Neither a pretreatment with Mg-ascorbyl phosphate or D,L-alpha-tocopherol, nor depletion of endogenous glutathione altered cellular sensitivity to UVB. In contrast, the DNA damaging effects of UVA could be counteracted by a pretreatment with these antioxidants. These observations confirm that the UVA-induced effects on DNA are related to radical mediated strand breaks and DNA lesions forming alkali-labile sites. The UVB-induced effects mainly occur as a consequence of excision repair-related strand breaks. The observed repair kinetics of DNA lesions and the influence of cellular antioxidant status may help to elucidate protective mechanisms against the carcinogenic effects of UV radiation present in sunlight.

  13. INVESTIGATION OF DNA REPAIR BY SISTER CHROMATID EXCHANGE (SCE) ANALYSIS AND THE ALKALINE SINGLE CELL GEL ASSAY (SCG) IN MAMMALIAN GO-LYMPHOCYTES AFTER IN VITRO EXPOSURE TO ETHYLENE OXIDE (EO)

    Science.gov (United States)

    Investigation ofDNA Repair by Sister Chromatid Exchange (SCE) Analysis and the Alkaline Single Cell Gel Assay (SCG) in Mammalian Go-Lymphocytes after In Vitro Exposure to Ethylene Oxide (EO). EO is a large volume chemical used primarily as an intermediate in manufacturing...

  14. Single cell enzyme diagnosis on the chip

    DEFF Research Database (Denmark)

    Jensen, Sissel Juul; Harmsen, Charlotte; Nielsen, Mette Juul

    2013-01-01

    Conventional diagnosis based on ensemble measurements often overlooks the variation among cells. Here, we present a droplet-microfluidics based platform to investigate single cell activities. Adopting a previously developed isothermal rolling circle amplification-based assay, we demonstrate detec...

  15. Use of single cell gel electrophoresis assays for the detection of DNA-protective effects of dietary factors in humans: recent results and trends.

    Science.gov (United States)

    Hoelzl, Christine; Knasmüller, Siegfried; Misík, Miroslav; Collins, Andrew; Dusinská, Maria; Nersesyan, Armen

    2009-01-01

    This article summarises the results of human dietary intervention trials employing the comet assay (single cell gel electrophoresis, SCGE), which have been published in the last few years (i.e., between 2005 and 2008) and describes new trends and developments as well as current problems concerning the design of intervention trials and the interpretation of the results. Most new studies were carried out with complex plant derived foods and juices; only a few were conducted with individual food constituents. With specific vegetables, for example with water cress and Brussels sprouts, potent antioxidant effects were observed; also coffee caused a protective effect and it is notable that it was more effective than consumption of a diet containing increased levels of fruits and vegetables. Interesting recent developments include the development of protocols which enable us to monitor protection towards genotoxic chemicals contained in the human diet, and it was shown in preliminary studies that alterations of the activities of drug metabolising enzymes by dietary factors lead to altered sensitivity of lymphocytes against DNA damage caused by certain dietary carcinogens. Another novel approach is the development of methods to monitor the effects of dietary factors on DNA repair. The development of protocols for experiments with exfoliated buccal cells is another potentially valuable innovation. The adequate experimental design of SCGE trials is still a matter of debate and the evaluation of the available data shows that there is an urgent need to develop guidelines concerning the number of participants, sampling periods, duration of trials, use of placebos, and definition of adequate run-in and wash-out phases. Recent studies showed that the results of dietary studies could be biased by factors such as age, sex, body mass index and life style habits and by seasonal effects. Another still unsolved problem is the interpretation of the results of SCGE trials in regard to

  16. Single Cell Isolation and Analysis

    Directory of Open Access Journals (Sweden)

    Ping Hu

    2016-10-01

    Full Text Available Increasing evidence shows that the heterogeneity of individual cells within a genetically identical population can be critical to their peculiar function and fate. Conventional cell based assays mainly analysis the average responses from a population cells, while the difference within individual cells may often be masked. The cell size, RNA transcripts and protein expression level are quite different within individual cells and these variations are key point to answer the problems in cancer, neurobiology, stem cell biology, immunology and developmental biology. To better understand the cell-to-cell variations, the single cell analysis can provide much more detailed information which may be helpful for therapeutic decisions in an increasingly personalized medicine. In this review, we will focus on the recent development in single cell analysis, including methods used in single cell isolation, analysis and some application examples. The review provides the historical background to single cell analysis, discusses limitations, and current and future possibilities in this exciting field of research.

  17. Single-step colony assay for screening antibody libraries.

    Science.gov (United States)

    Kato, Mieko; Hanyu, Yoshiro

    2017-08-10

    We describe a method, single-step colony assay, for simple and rapid screening of single-chain Fv fragment (scFv) libraries. Colonies of Escherichia coli expressing the scFv library are formed on a hydrophilic filter that is positioned in contact with a membrane coated with an antigen. scFv expression is triggered upon treatment of colonies with an induction reagent, following which scFvs are secreted from the cells and diffused to the antigen-coated membrane. scFvs that exhibit binding affinity for the antigen are captured by the membrane-immobilized antigen. Lastly, detection of scFv binding of the antigen on the membrane allows identification of the clones on the filter that express antigen-specific scFvs. We tested this methodology by using an anti-rabbit IgG scFv, scFv(A10B), and a rat immune scFv library. Experiments conducted using scFv(A10B) revealed that this method improves scFv expression during the colony assay. By using our method to screen an immune library of 3×10 3 scFv clones, we established several clones exhibiting affinity for the antigen. Moreover, we tested 7 other antigens, including peptides, and successfully identified positive clones. We believe that this simple procedure and controlled scFv expression of the single-step colony assay could make the antibody screening both rapid and reliable and lead to successful isolation of positive clones from antibody libraries. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Comet assay on mice testicular cells

    DEFF Research Database (Denmark)

    Sharma, Anoop Kumar

    2015-01-01

    of the comet assay in testicular cells. The chemicals included environmentally relevant substances such as Bisphenol A, PFOS and Tetrabrombisphenol A. Statistical power calculations will be presented to aid in the design of future Comet assay studies on testicular cells. Power curves were provided...

  19. Reference cells and ploidy in the comet assay

    Directory of Open Access Journals (Sweden)

    Gunnar eBrunborg

    2015-02-01

    Full Text Available In the comet assay, single cells are analyzed with respect to their level of DNA damage. Discrimination of the individual cell or cell type based on DNA content, with concomitant scoring of the DNA damage, is useful since this may allow analysis of mixtures of cells. Different cells can then be characterized based on their ploidy, cell cycle stage, or genome size. We here describe two applications of such a cell type-specific comet assay: (i Testicular cell suspensions, analyzed on the basis of their ploidy during spermatogenesis; and (ii reference cells in the form of fish erythrocytes which can be included as internal standards to correct for inter-assay variations. With standard fluorochromes used in the comet assay, the total staining signal from each cell – whether damaged or undamaged – was found to be associated with the cell’s DNA content. Analysis of the fluorescence intensity of single cells is straightforward since these data are available in scoring systems based on image analysis. The analysis of testicular cell suspensions provides information on cell type specific composition, susceptibility to genotoxicants, and DNA repair. Internal reference cells, either untreated or carrying defined numbers of lesions induced by ionizing radiation, are useful for investigation of experimental factors that can cause variation in comet assay results, and for routine inclusion in experiments to facilitate standardization of methods and comparison of comet assay data obtained in different experiments or in different laboratories. They can also be used - in combination with a reference curve - to quantify the DNA lesions induced by a certain treatment. Fish cells of a range of genome sizes, both greater and smaller than human, are suitable for this purpose and they are inexpensive.

  20. Comparative evaluation of the in vitro micronucleus test and the alkaline single cell gel electrophoresis assay for the detection of DNA damaging agents: genotoxic effects of cobalt powder, tungsten carbide and cobalt-tungsten carbide.

    Science.gov (United States)

    Van Goethem, F; Lison, D; Kirsch-Volders, M

    1997-08-01

    Although it is well known that micronuclei may arise from either DNA breakage leading to acentric chromosome fragments or from chromosome/chromatid lagging in anaphase, the ratio between the amount of DNA breakage induced and the frequency of micronuclei expressed in the following interphase is unclear. With the development of the alkaline single cell gel electrophoresis assay, which measures single strand and/or double strand breaks in a cell by cell approach, it is new possible to address this question at the cellular level. We therefore compared the genotoxic potential of pure cobalt powder (Co) and a cobalt-containing alloy, cobalt-tungsten carbide (WC-Co), involved in specific lung disorders, in parallel with the alkaline single cell gel electrophoresis (SCGE) assay (comet assay) and the cytokinesis-blocked micronucleus (MN) test, both carried out in vitro on isolated human leukocytes. The comet assay indicated that the WC-Co mixture produced a higher level of DNA damage than Co alone; WC alone was not able to induce a dose-dependent DNA breakage effect as was seen for Co and WC-Co. Results from the MN test confirmed these observations. It was clear that the clastogenic property of Co-containing dust is significantly enhanced when the Co metal is mixed with WC and suggested that their physicochemical characteristics may act as one of the important parameters responsible for the increased incidence of lung cancers observed in the population of hard metal workers. In agreement with data obtained in the same laboratory on liposoluble chemicals (PCBs and chlorinated aliphatic hydrocarbons) and from the literature, the results indicate that both the comet assay and the micronucleus test were able to detect differences in the genotoxic potential of the compounds studied. Although the micronucleus test seemed to be less sensitive to assess a synergistic DNA damaging potential of the mixture involved, it detects chromosomal aberrations (chromosome/genome mutations

  1. Assay of mast cell mediators

    DEFF Research Database (Denmark)

    Rådinger, Madeleine; Jensen, Bettina M; Swindle, Emily

    2015-01-01

    Mediator release from activated mast cells is a major initiator of the symptomology associated with allergic disorders such as anaphylaxis and asthma. Thus, methods to monitor the generation and release of such mediators have widespread applicability in studies designed to understand the processes...... regulating mast cell activation and for the identification of therapeutic approaches to block mast cell-driven disease. In this chapter, we discuss approaches used for the determination of mast cell degranulation, lipid-derived inflammatory mediator production, and cytokine/chemokine gene expression as well...

  2. Detection of gene copy number aberrations in mantle cell lymphoma by a single quantitative multiplex PCR assay: clinicopathological relevance and prognosis value.

    Science.gov (United States)

    Jardin, Fabrice; Picquenot, Jean-Michel; Parmentier, Françoise; Ruminy, Philippe; Cornic, Marie; Penther, Dominique; Bertrand, Philippe; Lanic, Hélène; Cassuto, Ophélie; Humbrecht, Catherine; Lemasle, Emilie; Wautier, Agathe; Bastard, Christian; Tilly, Hervé

    2009-09-01

    The t(11;14)(q13;q32) is the hallmark of mantle cell lymphoma (MCL). Additional genetic alterations occur in the majority of cases. This study aimed to design a polymerase chain reaction (PCR) assay to determine the incidence and relevance of recurrent gene copy number aberrations in this disease. Forty-two MCL cases with frozen- or paraffin-embedded (FFPE) tissues were selected. Three different quantitative Multiplex PCR of Short Fluorescent Fragments (QMPSF) assays were designed to simultaneously analyse eight genes (CDKN2A, RB1, ATM, CDK2, TP53, MYC, CDKN1B, MDM2), to analyse the 9p21 locus (CDKN2A/CDKN2B) and FFPE tissues. Gains of MYC, CDK2, CDKN1B, and MDM2 were observed in 10% of cases. Losses of RB1, CDKN2A, ATM or TP53 were observed in 38%, 31%, 24% and 10% of cases, respectively. Analysis of the 9p21 locus indicated that, in most cases, tumours displayed a complete inactivation of p14(ARF)/p15I(NK4B)/p16I(NK4A). CDKN2A and MYC aberrations were associated with a high MCL international prognostic index (MIPI). CDK2/MDM2 gains and CDKN2A/TP53 losses correlated with an unfavourable outcome. PCR experiments with frozen and FFPE-tissues indicated that our approach is valid in a routine diagnostic setting, providing a powerful tool that could be used for patient stratification in combination with MIPI in future clinical trials.

  3. Comet assay on mice testicular cells

    Directory of Open Access Journals (Sweden)

    Anoop Kumar Sharma

    2015-05-01

    Full Text Available Heritable mutations may result in a variety of adverse outcomes including genetic disease in the offspring. In recent years the focus on germ cell mutagenicity has increased and the “Globally Harmonized System of Classification and Labelling of Chemicals (GHS” has published classification criteria for germ cell mutagens (Speit et al., 2009. The in vivo Comet assay is considered a useful tool for investigating germ cell genotoxicity. In the present study DNA strand breaks in testicular cells of mice were investigated. Different classes of chemicals were tested in order to evaluate the sensitivity of the comet assay in testicular cells. The chemicals included environmentally relevant substances such as Bisphenol A, PFOS and Tetrabrombisphenol A. Statistical power calculations will be presented to aid in the design of future Comet assay studies on testicular cells. Power curves were provided with different fold changes in % tail DNA, different number of cells scored and different number of gels (Hansen et al., 2014. An example is shown in Figure 1. A high throughput version of the Comet assay was used. Samples were scored with a fully automatic comet assay scoring system that provided faster scoring of randomly selected cells.

  4. Single-Cell Western Blotting.

    Science.gov (United States)

    Sinkala, Elly; Herr, Amy E

    2015-01-01

    Little headway has been made in single cell protein analysis, aside from tools that rely solely on antibody-probe based detection (i.e., flow cytometry, immunocytochemistry), which are limited by low specificity and multiplexing capabilities. To address these protein analysis gaps, we have introduced a single-cell western blot (scWestern). The protein assay is capable of highly specific analysis by coupling antibody-based detection with a polyacrylamide gel electrophoresis (PAGE) protein separation. Cells are settled via gravity into polyacrylamide (PA) microwells, chemically lysed in the wells, and then subjected to PAGE through the walls of the microwells and into the surrounding PA gel. Over a thousand single-cell separations are performed simultaneously, and multiple protein targets of interest are investigated. After PAGE separation, photo-immobilization of all proteins to the gel allows for antibody probing and lends to the archival quality of the scWestern assay where new proteins targets can be investigated months after the initial separations are performed.

  5. Cell Culture Assay for Human Noroviruses [response

    Energy Technology Data Exchange (ETDEWEB)

    Straub, Tim M.; Honer Zu Bentrup, Kerstin; Orosz Coghlan, Patricia; Dohnalkova, Alice; Mayer, Brooke K.; Bartholomew, Rachel A.; Valdez, Catherine O.; Bruckner-Lea, Cindy J.; Gerba, Charles P.; Abbaszadegan, Morteza A.; Nickerson, Cheryl A.

    2007-07-01

    We appreciate the comments provided by Leung et al., in response to our recently published article “In Vitro Cell Culture Infectivity Assay for Human Noroviruses” by Straub et al. (1). The specific aim of our project was to develop an in vitro cell culture infectivity assay for human noroviruses (hNoV) to enhance risk assessments when they are detected in water supplies. Reverse transcription (RT) qualitative or quantitative PCR are the primary assays for waterborne NoV monitoring. However, these assays cannot distinguish between infectious vs. non-infectious virions. When hNoV is detected in water supplies, information provided by our infectivity assay will significantly improve risk assessment models and protect human health, regardless of whether we are propagating NoV. Indeed, in vitro cell culture infectivity assays for the waterborne pathogen Cryptosporidium parvum that supplement approved fluorescent microscopy assays, do not result in amplification of the environmentally resistant hard-walled oocysts (2). However, identification of life cycle stages in cell culture provides evidence of infectious oocysts in a water supply. Nonetheless, Leung et al.’s assertion regarding the suitability of our method for the in vitro propagation of high titers of NoV is valid for the medical research community. In this case, well-characterized challenge pools of virus would be useful for developing and testing diagnostics, therapeutics, and vaccines. As further validation of our published findings, we have now optimized RT quantitative PCR to assess the level of viral production in cell culture, where we are indeed finding significant increases in viral titer. The magnitude and time course of these increases is dependent on both virus strain and multiplicity of infection. We are currently preparing a manuscript that will discuss these findings in greater detail, and the implications this may have for creating viral challenge pools

  6. Comet assay on tetraploid yeast cells

    DEFF Research Database (Denmark)

    Rank, Jette; Syberg, Kristian; Jensen, Klara

    2009-01-01

    Tetraploid yeast cells (Saccharomyces cerevisiae) were used in the comet assay with the intention of developing a new, fast and easy assay for detecting environmental genotoxic agents without using higher organisms. Two DNA-damaging chemicals, H2O2 and acrylamide, together with wastewater from....... Analytical problems that arose due to the small amount of DNA in the yeast nuclei in haploid and diploid cells, which contain 13 Mbp and 26 Mbp DNA per cell, respectively, were solved by using tetraploid yeast cells (52 Mbp) instead. DNA damage was shown after exposure to H2O2 and acrylamide. The lowest dose...... causing significant DNA damage was 20 μM for H2O2 and 200 mg/l for acrylamide. Tertiary-treated wastewater from the outlets of three municipal wastewater-treatment plants was tested, but did not cause DNA damage. Even though it is possible to produce comets with tetraploid yeast cells, the amount of DNA...

  7. Detection of single nucleotide polymorphisms in p53 mutation hotspots and expression of mutant p53 in human cell lines using an enzyme-linked electrochemical assay

    Czech Academy of Sciences Publication Activity Database

    Horáková Brázdilová, Petra; Šimková, Eva; Vychodilová, Zdenka; Brázdová, Marie; Fojta, Miroslav

    2009-01-01

    Roč. 21, č. 15 (2009), s. 1723-1729 ISSN 1040-0397 R&D Projects: GA ČR(CZ) GA203/07/1195; GA AV ČR(CZ) IAA400040901; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : enzyme-linked electrochemical assay * SNP typing * p53 mutation Subject RIV: AQ - Safety, Health Protection, Human - Machine Impact factor: 2.630, year: 2009

  8. Defining cell culture conditions to improve human norovirus infectivity assays

    Energy Technology Data Exchange (ETDEWEB)

    Straub, Tim M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hutchison, Janine R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bartholomew, Rachel A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Valdez, Catherine O. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Valentine, Nancy B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dohnalkova, Alice [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ozanich, Richard M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bruckner-Lea, Cindy J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-01-10

    Significant difficulties remain for determining whether human noroviruses (hNoV) recovered from water, food, and environmental samples are infectious. Three-dimensional tissue culture of human intestinal cells has shown promise in developing an infectivity assay, but reproducibility, even within a single laboratory, remains problematic. From the literature and our observations, we hypothesized that the common factors that leads to more reproducible hNoV infectivity in vitro requires that the cell line be 1) of human gastrointestinal origin, 2) expresses apical microvilli, and 3) be a positive secretor cell line. The C2BBe1 cell line, which is a brush-border producing clone of Caco-2, meets these three criteria. When challenged with Genogroup II viruses, we observed a 2 Log10 increase in viral RNA titer. A passage experiment with GII viruses showed evidence of the ability to propagate hNoV by both reverse transcription quantitative PCR (qRT-PCR) and microscopy. Using 3-D C2BBe1 cells improves reproducibility of the infectivity assay for hNoV, but the assay can still be variable. Two sources of variability include the cells themselves (mixed phenotypes of small and large intestine) and initial titer measurements using quantitative reverse transcription PCR (qRT-PCR) that measures all RNA vs. plaque assays that measure infectious virus.

  9. An image-based, dual fluorescence reporter assay to evaluate the efficacy of shRNA for gene silencing at the single-cell level [v1; ref status: indexed, http://f1000r.es/2tt

    Directory of Open Access Journals (Sweden)

    Shin-ichiro Kojima

    2014-02-01

    Full Text Available RNA interference (RNAi is widely used to suppress gene expression in a specific manner. The efficacy of RNAi is mainly dependent on the sequence of small interfering RNA (siRNA in relation to the target mRNA. Although several algorithms have been developed for the design of siRNA, it is still difficult to choose a really effective siRNA from among multiple candidates. In this article, we report the development of an image-based, quantitative, ratiometric fluorescence reporter assay to evaluate the efficacy of RNAi at the single-cell level. Two fluorescence reporter constructs are used. One expresses the candidate small hairpin RNA (shRNA together with an enhanced green fluorescent protein (EGFP; the other expresses a 19-nt target sequence inserted into a cassette expressing a red fluorescent protein (either DsRed or mCherry. Effectiveness of the candidate shRNA is evaluated as the extent to which it knocks down expression of the red fluorescent protein. Thus, the red-to-green fluorescence intensity ratio (appropriately normalized to controls is used as the read-out for quantifying the siRNA efficacy at the individual cell level. We tested this dual fluorescence assay and compared predictions to actual endogenous knockdown levels for three different genes (vimentin, lamin A/C and Arp3 and twenty different shRNAs. For each of the genes, our assay successfully predicted the target sequences for effective RNAi. To further facilitate testing of RNAi efficacy, we developed a negative selection marker (ccdB method for construction of shRNA and red fluorescent reporter plasmids that allowed us to purify these plasmids directly from transformed bacteria without the need for colony selection and DNA sequencing verification.

  10. An image-based, dual fluorescence reporter assay to evaluate the efficacy of shRNA for gene silencing at the single-cell level [v2; ref status: indexed, http://f1000r.es/39j

    Directory of Open Access Journals (Sweden)

    Shin-ichiro Kojima

    2014-05-01

    Full Text Available RNA interference (RNAi is widely used to suppress gene expression in a specific manner. The efficacy of RNAi is mainly dependent on the sequence of small interfering RNA (siRNA in relation to the target mRNA. Although several algorithms have been developed for the design of siRNA, it is still difficult to choose a really effective siRNA from among multiple candidates. In this article, we report the development of an image-based, quantitative, ratiometric fluorescence reporter assay to evaluate the efficacy of RNAi at the single-cell level. Two fluorescence reporter constructs are used. One expresses the candidate small hairpin RNA (shRNA together with an enhanced green fluorescent protein (EGFP; the other expresses a 19-nt target sequence inserted into a cassette expressing a red fluorescent protein (either DsRed or mCherry. Effectiveness of the candidate shRNA is evaluated as the extent to which it knocks down expression of the red fluorescent protein. Thus, the red-to-green fluorescence intensity ratio (appropriately normalized to controls is used as the read-out for quantifying the siRNA efficacy at the individual cell level. We tested this dual fluorescence assay and compared predictions to actual endogenous knockdown levels for three different genes (vimentin, lamin A/C and Arp3 and twenty different shRNAs. For each of the genes, our assay successfully predicted the target sequences for effective RNAi. To further facilitate testing of RNAi efficacy, we developed a negative selection marker (ccdB method for construction of shRNA and red fluorescent reporter plasmids that allowed us to purify these plasmids directly from transformed bacteria without the need for colony selection and DNA sequencing verification.

  11. 21 CFR 864.7100 - Red blood cell enzyme assay.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Red blood cell enzyme assay. 864.7100 Section 864... enzyme assay. (a) Identification. Red blood cell enzyme assay is a device used to measure the activity in... kinase or 2,3-diphosphoglycerate. A red blood cell enzyme assay is used to determine the enzyme defects...

  12. Progress in Cell Based Assays for Botulinum Neurotoxin Detection

    Science.gov (United States)

    2013-01-01

    Botulinum neurotoxins (BoNTs) are the most potent human toxins known and the causative agent of botulism, and are widely used as valuable pharmaceuticals. The BoNTs are modular proteins consisting of a heavy chain and a light chain linked by a disulfide bond. Intoxication of neuronal cells by BoNTs is a multi-step process including specific cell binding, endocytosis, conformational change in the endosome, translocation of the enzymatic light chain into the cells cytosol, and SNARE target cleavage. The quantitative and reliable potency determination of fully functional BoNTs produced as active pharmaceutical ingredient (API) requires an assay that considers all steps in the intoxication pathway. The in vivo mouse bioassay has for years been the ‘gold standard’ assay used for this purpose, but it requires the use of large numbers of mice and thus causes associated costs and ethical concerns. Cell-based assays are currently the only in vitro alternative that detect fully functional BoNTs in a single assay and have been utilized for years for research purposes. Within the last 5 years, several cell-based BoNT detection assays have been developed that are able to quantitatively determine BoNT potency with similar or greater sensitivity than the mouse bioassay. These assays now offer an alternative method for BoNT potency determination. Such quantitative and reliable BoNT potency determination is a crucial step in basic research, in the development of pharmaceutical BoNTs, and in the quantitative detection of neutralizing antibodies. PMID:23239357

  13. Cell titration assay for measuring blastogenesis of bovine lymphocytes.

    Science.gov (United States)

    Baldwin, C L; Antczak, D F; Winter, A J

    1985-08-01

    The blastogenic response of bovine peripheral blood lymphocytes to phytohemagglutinin (PHA) and to microbial antigens was measured using a lymphocyte titration assay. Culture conditions, including lymphocyte concentrations, incubation periods and medium formulation, were established which produced linear or nearly linear responses over a range of cell concentrations. These conditions were established by testing lymphocytes from unimmunized cattle and from heifers infected with Brucella abortus with PHA and a B. abortus extract. Four cell concentrations in 2-fold increments were selected for measuring responses to PHA (3.125 X 10(3) to 2.5 X 10(4) cells/well) and to antigens (5.0 X 10(4) to 4.0 X 10(5) cells/well). The strength of response varied among animals and also over time for individual animals, but the titration assay allowed exponential proliferation to be distinguished from decline, which may have been due to overcrowding of microtiter wells, exhaustion of nutrients or induction of regulatory events. This assay provided a more reliable and discriminating method of evaluating lymphocyte proliferation responses than that achieved by single point assays. The displacement of the titration curves could be used to estimate the relative frequency of lymphocytes responding to antigens or mitogens.

  14. Heated oligonucleotide ligation assay (HOLA): an affordable single nucleotide polymorphism assay.

    Science.gov (United States)

    Black, W C; Gorrochotegui-Escalante, N; Duteau, N M

    2006-03-01

    Most single nucleotide polymorphism (SNP) detection requires expensive equipment and reagents. The oligonucleotide ligation assay (OLA) is an inexpensive SNP assay that detects ligation between a biotinylated "allele-specific detector" and a 3' fluorescein-labeled "reporter" oligonucleotide. No ligation occurs unless the 3' detector nucleotide is complementary to the SNP nucleotide. The original OLA used chemical denaturation and neutralization. Heated OLA (HOLA) instead uses a thermal stable ligase and cycles of denaturing and hybridization for ligation and SNP detection. The cost per genotype is approximately US$1.25 with two-allele SNPs or approximately US$1.75 with three-allele SNPs. We illustrate the development of HOLA for SNP detection in the Early Trypsin and Abundant Trypsin loci in the mosquito Aedes aegypti (L.) and at the a-glycerophosphate dehydrogenase locus in the mosquito Anopheles gambiae s.s.

  15. Genotoxicity of three food processing contaminants in transgenic mice expressing human sulfotransferases 1A1 and 1A2 as assessed by the in vivo alkaline single cell gel electrophoresis assay.

    Science.gov (United States)

    Høie, Anja Hortemo; Svendsen, Camilla; Brunborg, Gunnar; Glatt, Hansruedi; Alexander, Jan; Meinl, Walter; Husøy, Trine

    2015-10-01

    The food processing contaminants 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 5-hydroxymethylfurfural (HMF) and 2,5 dimethylfuran (DMF) are potentially both mutagenic and carcinogenic in vitro and/or in vivo, although data on DMF is lacking. The PHIP metabolite N-hydroxy-PhIP and HMF are bioactivated by sulfotransferases (SULTs). The substrate specificity and tissue distribution of SULTs differs between species. A single oral dose of PhIP, HMF or DMF was administered to wild-type (wt) mice and mice expressing human SULT1A1/1A2 (hSULT mice). DNA damage was studied using the in vivo alkaline single cell gel electrophoresis (SCGE) assay. No effects were detected in wt mice. In the hSULT mice, PhIP and HMF exposure increased the levels of DNA damage in the liver and kidney, respectively. DMF was not found to be genotoxic. The observation of increased DNA damage in hSULT mice compared with wt mice supports the role of human SULTs in the bioactivation of N-hydroxy-PhIP and HMF in vivo. © 2015 The Authors. Environmental and Molecular Mutagenesis Published by Wiley Periodicals, Inc.

  16. Subcellular western blotting of single cells.

    Science.gov (United States)

    Yamauchi, Kevin A; Herr, Amy E

    2017-01-01

    Although immunoassays are the de facto standard for determining subcellular protein localization in individual cells, antibody probe cross-reactivity and fixation artifacts remain confounding factors. To enhance selectivity while providing single-cell resolution, we introduce a subcellular western blotting technique capable of separately assaying proteins in the 14 pL cytoplasm and 2 pL nucleus of individual cells. To confer precision fluidic control, we describe a passive multilayer microdevice that leverages the rapid transport times afforded by miniaturization. After isolating single cells in microwells, we apply single-cell differential detergent fractionation to lyse and western blot the cytoplasmic lysate, whereas the nucleus remains intact in the microwell. Subsequently, we lyse the intact nucleus and western blot the nuclear lysate. To index each protein analysis to the originating subcellular compartment, we utilize bi-directional electrophoresis, a multidimensional separation that assays the lysate from each compartment in a distinct region of the separation axis. Single-cell bi-directional electrophoresis eliminates the need for semi-subjective image segmentation algorithms required in immunocytochemistry. The subcellular, single-cell western blot is demonstrated for six targets per cell, and successfully localizes spliceosome-associated proteins solubilized from large protein and RNA complexes, even for closely sized proteins (a 7 kDa difference). Measurement of NF-κB translocation dynamics in unfixed cells at 15-min intervals demonstrates reduced technical variance compared with immunofluorescence. This chemical cytometry assay directly measures the nucleocytoplasmic protein distribution in individual unfixed cells, thus providing insight into protein signaling in heterogeneous cell populations.

  17. Microfluidics for single cell analysis

    DEFF Research Database (Denmark)

    Jensen, Marie Pødenphant

    Isolation and manipulation of single cells have gained an increasing interest from researchers because of the heterogeneity of cells from the same cell culture. Single cell analysis can ensure a better understanding of differences between individual cells and potentially solve a variety of clinical...... problems. In this thesis lab on a chip systems for rare single cell analysis are investigated. The focus was to develop a commercial, disposable device for circulating tumour cell (CTC) analysis. Such a device must be able to separate rare cells from blood samples and subsequently capture the specific...... cells, and simultaneously be fabricated and operated at low costs and be user-friendly. These challenges were addressed through development of two microfluidic devices, one for rare cell isolation based on pinched flow fractionation (PFF) and one for single cell capture based on hydrodynamic trapping...

  18. A dual immunocytochemical assay for oestrogen and epidermal growth factor receptors in tumour cell lines

    NARCIS (Netherlands)

    A.K. Sharma (Anisha K.); J.H. Horgan; R.L. McClelland (Robyn); A.G. Douglas-Jones (A.); T. van Agthoven (Ton); L.C.J. Dorssers (Lambert); R.I. Nicholson (R.)

    1994-01-01

    textabstractA new dual immunocytochemical assay for oestrogen receptor (ER) and epidermal growth factor receptor (EGFR) has been developed. It has been tested in a variety of conditions using cell culture lines and the results correlate well with those obtained from single immunocytochemical assays.

  19. Automated reagent-dispensing system for microfluidic cell biology assays.

    Science.gov (United States)

    Ly, Jimmy; Masterman-Smith, Michael; Ramakrishnan, Ravichandran; Sun, Jing; Kokubun, Brent; van Dam, R Michael

    2013-12-01

    Microscale systems that enable measurements of oncological phenomena at the single-cell level have a great capacity to improve therapeutic strategies and diagnostics. Such measurements can reveal unprecedented insights into cellular heterogeneity and its implications into the progression and treatment of complicated cellular disease processes such as those found in cancer. We describe a novel fluid-delivery platform to interface with low-cost microfluidic chips containing arrays of microchambers. Using multiple pairs of needles to aspirate and dispense reagents, the platform enables automated coating of chambers, loading of cells, and treatment with growth media or other agents (e.g., drugs, fixatives, membrane permeabilizers, washes, stains, etc.). The chips can be quantitatively assayed using standard fluorescence-based immunocytochemistry, microscopy, and image analysis tools, to determine, for example, drug response based on differences in protein expression and/or activation of cellular targets on an individual-cell level. In general, automation of fluid and cell handling increases repeatability, eliminates human error, and enables increased throughput, especially for sophisticated, multistep assays such as multiparameter quantitative immunocytochemistry. We report the design of the automated platform and compare several aspects of its performance to manually-loaded microfluidic chips.

  20. Analysis of single biological cells

    International Nuclear Information System (INIS)

    Watt, Frank

    2002-01-01

    The extraction of elemental information from single cultured cells using nuclear microscopy is an area of great potential because it can provide both quantitative information on the uptake of elements by the cell, and also its elemental response to a wide variety of external stimuli. A recent technique based on nuclear physics technology enables the analysis of single cells down to the parts per million level to be achieved

  1. The potential of single-cell profiling in plants.

    Science.gov (United States)

    Efroni, Idan; Birnbaum, Kenneth D

    2016-04-05

    Single-cell transcriptomics has been employed in a growing number of animal studies, but the technique has yet to be widely used in plants. Nonetheless, early studies indicate that single-cell RNA-seq protocols developed for animal cells produce informative datasets in plants. We argue that single-cell transcriptomics has the potential to provide a new perspective on plant problems, such as the nature of the stem cells or initials, the plasticity of plant cells, and the extent of localized cellular responses to environmental inputs. Single-cell experimental outputs require different analytical approaches compared with pooled cell profiles and new tools tailored to single-cell assays are being developed. Here, we highlight promising new single-cell profiling approaches, their limitations as applied to plants, and their potential to address fundamental questions in plant biology.

  2. Single cell electroporation on chip

    NARCIS (Netherlands)

    Valero, Ana

    2006-01-01

    In this thesis the results of the development of microfluidic cell trap devices for single cell electroporation are described, which are to be used for gene transfection. The performance of two types of Lab-on-a-Chip trapping devices was tested using beads and cells, whereas the functionality for

  3. A single nucleotide polymorphism (SNP) assay for population ...

    African Journals Online (AJOL)

    Therefore, we developed the first SNP assay to test stratification between Chinese and Japanese populations living in East Asia. The ancestry ... The SNP assay showed excellent promise as a highly potential application to test population stratification in case-control studies of association in Eastern Asians. Key words: ...

  4. Optimization of cell motility evaluation in scratch assay

    Directory of Open Access Journals (Sweden)

    Gotsulyak N. Ya.

    2014-05-01

    Full Text Available A scratch test is one of the most popular methods of classical cell migration assay in a monolayer culture. At the same time, the scratch assay has some disadvantages that can be easily corrected. Aim. Optimization the existent scratch assay on the base of detection of scratch wound surface area and the length of the field of observation which is more objective and less time consuming. Methods. Scratch assay. Results. The modification of scratch assay enables to perform measurement more accurately and rapidly. This approach is more simple and eliminates the main disadvantages of the classical method. Conclusions. The procedure of scratch wound width measurement calculated on the base of detection of cell free area and the length of the field of observation is more effective than the classical wound healing assay. It will be useful for the estimation of cell migration dynamics in monolayer culture for a wide range of live cell based experiments.

  5. Single-cell western blotting.

    Science.gov (United States)

    Quadri, Syed M S

    2015-01-01

    Cell heterogeneity is a variation in cellular processes in functionally similar cells. Cells from the same tissue which are considered genetically identical may have difference in size, structure, and level of protein expression which can lead to major impact on the functions of cell leading to difference in physiological consequences. Single-cell proteome-wide studies are used to detect cell heterogeneity. Flow cytometry and immunocytochemistry do play an important role in evaluating cell heterogeneity. However, these methods are based on separation by antibodies with limited specificity. Cross-reactivity can occur leading to bias in result. Western blot is done to separate the proteins according to molecular weight. Therefore, off-target and on-target signals can be discriminated. Detection of protein expression from a tissue can be done with the help of western blot. However, it is unable to differentiate protein expression of individual cells. For detection of this cell-to-cell variation, a highly advanced technique termed "single-cell western blotting" is carried out. Single-cell western blot has enabled us to detect protein expression at cellular level at a fairly advanced high resolution using a western blot designed to assess cell heterogeneity.

  6. Measuring single-cell density.

    Science.gov (United States)

    Grover, William H; Bryan, Andrea K; Diez-Silva, Monica; Suresh, Subra; Higgins, John M; Manalis, Scott R

    2011-07-05

    We have used a microfluidic mass sensor to measure the density of single living cells. By weighing each cell in two fluids of different densities, our technique measures the single-cell mass, volume, and density of approximately 500 cells per hour with a density precision of 0.001 g mL(-1). We observe that the intrinsic cell-to-cell variation in density is nearly 100-fold smaller than the mass or volume variation. As a result, we can measure changes in cell density indicative of cellular processes that would be otherwise undetectable by mass or volume measurements. Here, we demonstrate this with four examples: identifying Plasmodium falciparum malaria-infected erythrocytes in a culture, distinguishing transfused blood cells from a patient's own blood, identifying irreversibly sickled cells in a sickle cell patient, and identifying leukemia cells in the early stages of responding to a drug treatment. These demonstrations suggest that the ability to measure single-cell density will provide valuable insights into cell state for a wide range of biological processes.

  7. An improved method for staining cell colonies in clonogenic assays

    OpenAIRE

    Guda, Kishore; Natale, Leanna; Markowitz, Sanford D.

    2007-01-01

    Clonogenic assay is a widely used experimental approach to test for the effects of drugs/genes on the growth and proliferative characteristics of cells in vitro. Accurate quantitation of treatment effects in clonogeneic assays depends on the ability to visualize and count cell colonies precisely. We report a novel method (referred as ETeB) for staining cell colonies grown on plastic and specially coated substrates like collagen. Using colon cancer cell lines grown on plastic and collagen, we ...

  8. Single cell-resolution western blotting.

    Science.gov (United States)

    Kang, Chi-Chih; Yamauchi, Kevin A; Vlassakis, Julea; Sinkala, Elly; Duncombe, Todd A; Herr, Amy E

    2016-08-01

    This protocol describes how to perform western blotting on individual cells to measure cell-to-cell variation in protein expression levels and protein state. Like conventional western blotting, single-cell western blotting (scWB) is particularly useful for protein targets that lack selective antibodies (e.g., isoforms) and in cases in which background signal from intact cells is confounding. scWB is performed on a microdevice that comprises an array of microwells molded in a thin layer of a polyacrylamide gel (PAG). The gel layer functions as both a molecular sieving matrix during PAGE and a blotting scaffold during immunoprobing. scWB involves five main stages: (i) gravity settling of cells into microwells; (ii) chemical lysis of cells in each microwell; (iii) PAGE of each single-cell lysate; (iv) exposure of the gel to UV light to blot (immobilize) proteins to the gel matrix; and (v) in-gel immunoprobing of immobilized proteins. Multiplexing can be achieved by probing with antibody cocktails and using antibody stripping/reprobing techniques, enabling detection of 10+ proteins in each cell. We also describe microdevice fabrication for both uniform and pore-gradient microgels. To extend in-gel immunoprobing to gels of small pore size, we describe an optional gel de-cross-linking protocol for more effective introduction of antibodies into the gel layer. Once the microdevice has been fabricated, the assay can be completed in 4-6 h by microfluidic novices and it generates high-selectivity, multiplexed data from single cells. The technique is relevant when direct measurement of proteins in single cells is needed, with applications spanning the fundamental biosciences to applied biomedicine.

  9. Isolation, Culture, Functional Assays, and Immunofluorescence of Myofiber-Associated Satellite Cells.

    Science.gov (United States)

    Vogler, Thomas O; Gadek, Katherine E; Cadwallader, Adam B; Elston, Tiffany L; Olwin, Bradley B

    2016-01-01

    Adult skeletal muscle stem cells, termed satellite cells, regenerate and repair the functional contractile cells in adult skeletal muscle called myofibers. Satellite cells reside in a niche between the basal lamina and sarcolemma of myofibers. Isolating single myofibers and their associated satellite cells provides a culture system that partially mimics the in vivo environment. We describe methods for isolating and culturing intact individual myofibers and their associated satellite cells from the mouse extensor digitorum longus muscle. Following dissection and isolation of individual myofibers we provide protocols for myofiber transplantation, satellite cell transfection, immune detection of satellite cell antigens, and assays to examine satellite cell self-renewal and proliferation.

  10. Single Molecule Spectroscopy: Single Live Cell

    Indian Academy of Sciences (India)

    kbhattacharjee

    Live Cell Imaging: Seeing inside a cell. • Cell: ~20,000 nm ~ 100 times bigger than focus. • Label different parts of a cell with fluorescent dye. • Cancer Cell: How different from a normal cell? cell. Space & time resolution ...

  11. Improving Precision of Proximity Ligation Assay by Amplified Single Molecule Detection

    OpenAIRE

    Ke, Rongqin; Nong, Rachel Yuan; Fredriksson, Simon; Landegren, Ulf; Nilsson, Mats

    2013-01-01

    Proximity ligation assay (PLA) has been proven to be a robust protein detection method. The technique is characterized by high sensitivity and specificity, but the assay precision is probably limited by the PCR readout. To investigate this potential limitation and to improve precision, we developed a digital proximity ligation assay for protein measurement in fluids based on amplified single molecule detection. The assay showed significant improvements in precision, and thereby also detection...

  12. High content cell-based assay for the inflammatory pathway

    Science.gov (United States)

    Mukherjee, Abhishek; Song, Joon Myong

    2015-07-01

    Cellular inflammation is a non-specific immune response to tissue injury that takes place via cytokine network orchestration to maintain normal tissue homeostasis. However chronic inflammation that lasts for a longer period, plays the key role in human diseases like neurodegenerative disorders and cancer development. Understanding the cellular and molecular mechanisms underlying the inflammatory pathways may be effective in targeting and modulating their outcome. Tumor necrosis factor alpha (TNF-α) is a pro-inflammatory cytokine that effectively combines the pro-inflammatory features with the pro-apoptotic potential. Increased levels of TNF-α observed during acute and chronic inflammatory conditions are believed to induce adverse phenotypes like glucose intolerance and abnormal lipid profile. Natural products e. g., amygdalin, cinnamic acid, jasmonic acid and aspirin have proven efficacy in minimizing the TNF-α induced inflammation in vitro and in vivo. Cell lysis-free quantum dot (QDot) imaging is an emerging technique to identify the cellular mediators of a signaling cascade with a single assay in one run. In comparison to organic fluorophores, the inorganic QDots are bright, resistant to photobleaching and possess tunable optical properties that make them suitable for long term and multicolor imaging of various components in a cellular crosstalk. Hence we tested some components of the mitogen activated protein kinase (MAPK) pathway during TNF-α induced inflammation and the effects of aspirin in HepG2 cells by QDot multicolor imaging technique. Results demonstrated that aspirin showed significant protective effects against TNF-α induced cellular inflammation. The developed cell based assay paves the platform for the analysis of cellular components in a smooth and reliable way.

  13. A novel in vitro assay for murine haematopoietic stem cells.

    Science.gov (United States)

    Eckmann, L; Freshney, M; Wright, E G; Sproul, A; Wilkie, N; Pragnell, I B

    1988-12-01

    Study of the biology of haematopoietic stem cells is crucially dependent on the availability of suitable in vitro assays. Existing assays have suffered from the fact that they detect small subcompartments of the total stem cell compartment. This limits experiments where it is required to assay a high proportion of stem cells, e.g. the enumeration of stem cell numbers under varying conditions or the identification and purification of stem cell regulators. We describe an in vitro assay which shows macroscopic colony formation and limited self-renewal capacity in vitro. The detected cell (CFU-A) has a low cycling status in normal bone marrow (NBM) and responds to known stem cell regulators. The incidence (100-200 per 10(5) in NBM), the proliferative characteristics under stress and some of the physical properties are similar to stem cells detected by colony formation after transplantation into lethally irradiated recipients (CFU-S). These data indicate that our assay detects a high proportion of haematopoietic stem cells in vitro. This will facilitate experiments on stem cell behaviour which have previously been difficult to conduct.

  14. Plant single-cell and single-cell-type metabolomics.

    Science.gov (United States)

    Misra, Biswapriya B; Assmann, Sarah M; Chen, Sixue

    2014-10-01

    In conjunction with genomics, transcriptomics, and proteomics, plant metabolomics is providing large data sets that are paving the way towards a comprehensive and holistic understanding of plant growth, development, defense, and productivity. However, dilution effects from organ- and tissue-based sampling of metabolomes have limited our understanding of the intricate regulation of metabolic pathways and networks at the cellular level. Recent advances in metabolomics methodologies, along with the post-genomic expansion of bioinformatics knowledge and functional genomics tools, have allowed the gathering of enriched information on individual cells and single cell types. Here we review progress, current status, opportunities, and challenges presented by single cell-based metabolomics research in plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. A sensitive branched DNA HIV-1 signal amplification viral load assay with single day turnaround.

    Directory of Open Access Journals (Sweden)

    Mark A Baumeister

    Full Text Available Branched DNA (bDNA is a signal amplification technology used in clinical and research laboratories to quantitatively detect nucleic acids. An overnight incubation is a significant drawback of highly sensitive bDNA assays. The VERSANT® HIV-1 RNA 3.0 Assay (bDNA ("Versant Assay" currently used in clinical laboratories was modified to allow shorter target incubation, enabling the viral load assay to be run in a single day. To dramatically reduce the target incubation from 16-18 h to 2.5 h, composition of only the "Lysis Diluent" solution was modified. Nucleic acid probes in the assay were unchanged. Performance of the modified assay (assay in development; not commercially available was evaluated and compared to the Versant Assay. Dilution series replicates (>950 results were used to demonstrate that analytical sensitivity, linearity, accuracy, and precision for the shorter modified assay are comparable to the Versant Assay. HIV RNA-positive clinical specimens (n = 135 showed no significant difference in quantification between the modified assay and the Versant Assay. Equivalent relative quantification of samples of eight genotypes was demonstrated for the two assays. Elevated levels of several potentially interfering endogenous substances had no effect on quantification or specificity of the modified assay. The modified assay with drastically improved turnaround time demonstrates the viability of signal-amplifying technology, such as bDNA, as an alternative to the PCR-based assays dominating viral load monitoring in clinical laboratories. Highly sensitive bDNA assays with a single day turnaround may be ideal for laboratories with especially stringent cost, contamination, or reliability requirements.

  16. Mapping Cellular Hierarchy by Single-Cell Analysis of the Cell Surface Repertoire

    OpenAIRE

    Guo, Guoji; Luc, Sidinh; Marco, Eugenio; Lin, Ta-Wei; Peng, Cong; Kerenyi, Marc A.; Beyaz, Semir; Kim, Woojin; Xu, Jian; Das, Partha Pratim; Neff, Tobias; Zou, Keyong; Yuan, Guo-Cheng; Orkin, Stuart H.

    2013-01-01

    Stem cell differentiation pathways are most often studied at the population level, whereas critical decisions are executed at the level of single cells. We have established a highly multiplexed, quantitative PCR assay to profile in an unbiased manner a panel of all commonly used cell surface markers (280 genes) from individual cells. With this method we analyzed over 1500 single cells throughout the mouse hematopoietic system, and illustrate its utility for revealing important biological insi...

  17. Single-cell photoacoustic thermometry.

    Science.gov (United States)

    Gao, Liang; Wang, Lidai; Li, Chiye; Liu, Yan; Ke, Haixin; Zhang, Chi; Wang, Lihong V

    2013-02-01

    A novel photoacoustic thermometric method is presented for simultaneously imaging cells and sensing their temperature. With three-seconds-per-frame imaging speed, a temperature resolution of 0.2°C was achieved in a photo-thermal cell heating experiment. Compared to other approaches, the photoacoustic thermometric method has the advantage of not requiring custom-developed temperature-sensitive biosensors. This feature should facilitate the conversion of single-cell thermometry into a routine lab tool and make it accessible to a much broader biological research community.

  18. A novel microculture kinetic assay (MiCK assay) for malignant cell growth and chemosensitivity.

    Science.gov (United States)

    Kravtsov, V D

    1994-01-01

    The THERMOmax microplate reader was adapted for monitoring the growth kinetics of human leukaemic OCI/AML-2 and mouse tumour J-774.1 cell lines in continuous culture. Fluid evaporation from wells, CO2 escape and contamination were prevented by hermetic sealing of the microcultures in wells of a 96-well microplate, thus enabling the cells to grow exponentially for 72 h under the conditions of the incubated microplate reader. For both OCI/AML-2 cells, which grow in suspension, and adherent J-774.1 cells, a linear correlation was demonstrated between the number of unstained cells seeded in a given microplate well and the optical density (OD) of that well. Therefore, the OD/time curve of the culture could be deemed to be its growth curve. By the use of the linear fit equation, the actual number of the cells in the wells was computable at any time point of the assay. In the chemosensitivity test, an inhibitory effect of ARA-C on the growth of the cells could be estimated by viewing of the growth curves plotted on the screen. The maximum kinetic rates (Vmax) of the curves in the control and the ARA-C-treated wells were compared, yielding a growth inhibition index (GII). Comparison of results of the kinetic chemosensitivity assay with those of a [3H]thymidine incorporation assay revealed that the novel assay is suitable for precise quantitation of the cell chemosensitivity, is more informative and has the added technical advantage of performance without recourse to radioactive or chemically hazardous substances.

  19. Microfluidics-Enabled Enzyme Activity Measurement in Single Cells.

    Science.gov (United States)

    Tesauro, Cinzia; Frøhlich, Rikke; Stougaard, Magnus; Ho, Yi-Ping; Knudsen, Birgitta R

    2015-01-01

    Cellular heterogeneity has presented a significant challenge in the studies of biology. While most of our understanding is based on the analysis of ensemble average, individual cells may process information and respond to perturbations very differently. Presented here is a highly sensitive platform capable of measuring enzymatic activity at the single-cell level. The strategy innovatively combines a rolling circle-enhanced enzyme activity detection (REEAD) assay with droplet microfluidics. The single-molecule sensitivity of REEAD allows highly sensitive detection of enzymatic activities, i.e. at the single catalytic event level, whereas the microfluidics enables isolation of single cells. Further, confined reactions in picoliter-sized droplets significantly improve enzyme extraction from human cells or microorganisms and result in faster reaction kinetics. Taken together, the described protocol is expected to open up new possibilities in the single-cell research, particularly for the elucidation of heterogeneity in a population of cells.

  20. Mammalian cell HPRT gene mutation assay: test methods.

    Science.gov (United States)

    Johnson, George E

    2012-01-01

    Using the combination of bacterial gene mutation assay and chromosomal aberrations test in mammalian cells may not detect a small proportion of mammalian specific mutagenic agents. Therefore, at the current time a third assay should be used, except for compounds for which there is little or no exposure (DOH (2000) Department of Health Guidance for the testing of chemicals for Mutagenicity. Committee on Mutagenicity of Chemicals in Food, Consumer Products and the Environment). The hypoxanthine phosphorybosyl transferase (HPRT) gene is on the X chromosome of mammalian cells, and it is used as a model gene to investigate gene mutations in mammalian cell lines. The assay can detect a wide range of chemicals capable of causing DNA damage that leads to gene mutation. The test follows a very similar methodology to the thymidine kinase (TK) mouse lymphoma assay (MLA), and both are included in the guidelines for mammalian gene mutation tests (OECD (1997) Organisation for Economic Co-operation and Development. Ninth addendum to the OECD Guidelines for the Testing of Chemicals. In Vitro Mammalian Cell Gene Mutation Test: 476). The HPRT methodology is such that mutations which destroy the functionality of the HPRT gene and or/protein are detected by positive selection using a toxic analogue, and HPRT ( - ) mutants are seen as viable colonies. Unlike bacterial reverse mutation assays, mammalian gene mutation assays respond to a broad spectrum of mutagens, since any mutation resulting in the ablation of gene expression/function produces a HPRT ( - ) mutant. Human cells are readily used, and mechanistic studies using the HPRT test methodology with modifications, such as knock-out cell lines for DNA repair, can provide details of the mode of action (MOA) of the test compound (24).This chapter provides the methodology for carrying out the assay in different cell lines in the presence and absence of metabolism with technical information and general advice on how to carry out the

  1. In vitro mutagenicity and genotoxicity study of 1,2-dichloroethylene, 1,1,2-trichloroethane, 1,3-dichloropropane, 1,2,3-trichloropropane and 1,1,3-trichloropropene, using the micronucleus test and the alkaline single cell gel electrophoresis technique (comet assay) in human lymphocytes.

    Science.gov (United States)

    Tafazoli, M; Kirsch-Volders, M

    1996-12-20

    The main objective of this study was to compare the cytotoxic genotoxic and mutagenic activity of a number of chlorinated aliphatic hydrocarbons, which are widely used as chemical intermediates, solvents, degreasing agents etc. in industry, and to establish the structure-toxicity relationship of the chemicals by using the most adequate determinants in estimating their toxicity. The mutagenicity and cytotoxicity of some of the candidate chemicals, namely 1,2-dichloroethylene, 1,1,2-trichloroethane, 1,3-dichloropropane, 1,2,3-trichloropropane and 1,1,3-trichloropropene were evaluated in an in vitro micronucleus assay. The cytokinesis-block methodology was applied on human lymphocytes in the presence or absence of an external metabolic activation system (S9-mix). In the micronucleus assay, all test substances, except 1,2,3-trichloropropane with and without S9-mix and 1,1,2-trichloroethane without S9-mix in the repeated experiment, exhibited a low but statistically significant mutagenic activity, compared to the concurrent control. However, none of the five chemicals was able to induce a clear and reproducible linear dose-dependent increase in micronucleus frequencies in this assay. Generally, mutagenic activity of the chemicals was found in the absence of severe cytotoxicity and/or cell cycle delay. The DNA breakage capacity and the cytotoxicity of these chemicals were also assessed in the alkaline single cell gel (SCG) electrophoresis test (comet assay) with and without S9-mix in isolated human lymphocytes. All chemical compounds induced DNA breakage, in the presence or absence of the metabolic activation system, at the doses tested. The data showed that the DNA reactivity of the chemicals increased with increasing degree of halogenation. The results of the present work suggested that the comet assay might be a more suitable and sensitive screening method than the micronucleus test for this particular class of compound. However, both assays do detect different

  2. Mathematical models of cytotoxic effects in endpoint tumor cell line assays: critical assessment of the application of a single parametric value as a standard criterion to quantify the dose-response effects and new unexplored proposal formats.

    Science.gov (United States)

    Calhelha, Ricardo C; Martínez, Mireia A; Prieto, M A; Ferreira, Isabel C F R

    2017-10-23

    The development of convenient tools for describing and quantifying the effects of standard and novel therapeutic agents is essential for the research community, to perform more precise evaluations. Although mathematical models and quantification criteria have been exchanged in the last decade between different fields of study, there are relevant methodologies that lack proper mathematical descriptions and standard criteria to quantify their responses. Therefore, part of the relevant information that can be drawn from the experimental results obtained and the quantification of its statistical reliability are lost. Despite its relevance, there is not a standard form for the in vitro endpoint tumor cell lines' assays (TCLA) that enables the evaluation of the cytotoxic dose-response effects of anti-tumor drugs. The analysis of all the specific problems associated with the diverse nature of the available TCLA used is unfeasible. However, since most TCLA share the main objectives and similar operative requirements, we have chosen the sulforhodamine B (SRB) colorimetric assay for cytotoxicity screening of tumor cell lines as an experimental case study. In this work, the common biological and practical non-linear dose-response mathematical models are tested against experimental data and, following several statistical analyses, the model based on the Weibull distribution was confirmed as the convenient approximation to test the cytotoxic effectiveness of anti-tumor compounds. Then, the advantages and disadvantages of all the different parametric criteria derived from the model, which enable the quantification of the dose-response drug-effects, are extensively discussed. Therefore, model and standard criteria for easily performing the comparisons between different compounds are established. The advantages include a simple application, provision of parametric estimations that characterize the response as standard criteria, economization of experimental effort and enabling

  3. A Morphological identification cell cytotoxicity assay using cytoplasm-localized fluorescent probe (CLFP) to distinguish living and dead cells.

    Science.gov (United States)

    Lai, Fangfang; Shen, Zhengwei; Wen, Hui; Chen, Jialing; Zhang, Xiang; Lin, Ping; Yin, Dali; Cui, Huaqing; Chen, Xiaoguang

    2017-01-08

    Cell cytotoxicity assays include cell activity assays and morphological identification assays. Currently, all frequently used cytotoxicity assays belong to cell activity assays but suffer from detection limitations. Morphological identification of cell death remains as the gold standard, although the method is difficult to scale up. At present there is no generally accepted morphological identification based cell cytotoxicity assay. In this study, we applied previous developed cell cytoplasm-localized fluorescent probe (CLFP) to display cell morphologies. Under fluorescence microscopy, the fluorescence morphology and intensity of living cells are distinct from dead cells. Based on these characters we extracted the images of living cells from series of samples via computational analysis. Thus, a novel cell morphological identification cytotoxicity assay (CLFP assay) is developed. The performance of the CLFP assay was similar to cell activity assay (MTT assay), but the accuracy of the CLFP assay was superior when measuring the cytotoxicity of active compounds. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Single-Cell Genomic Analysis in Plants

    Directory of Open Access Journals (Sweden)

    Yuxuan Yuan

    2018-01-01

    Full Text Available Individual cells in an organism are variable, which strongly impacts cellular processes. Advances in sequencing technologies have enabled single-cell genomic analysis to become widespread, addressing shortcomings of analyses conducted on populations of bulk cells. While the field of single-cell plant genomics is in its infancy, there is great potential to gain insights into cell lineage and functional cell types to help understand complex cellular interactions in plants. In this review, we discuss current approaches for single-cell plant genomic analysis, with a focus on single-cell isolation, DNA amplification, next-generation sequencing, and bioinformatics analysis. We outline the technical challenges of analysing material from a single plant cell, and then examine applications of single-cell genomics and the integration of this approach with genome editing. Finally, we indicate future directions we expect in the rapidly developing field of plant single-cell genomic analysis.

  5. Application of the comet assay in studies of programmed cell death (PCD in plants

    Directory of Open Access Journals (Sweden)

    Maria Charzyńska

    2014-01-01

    Full Text Available Programmed cell death (PCD in plants is an intensively investigated process. One of the main characteristics of PCD in both animal and plant organisms is the non-random, internucleosomal fragmentation of nuclear DNA, usually analysed using total DNA gel electrophoresis or TUNEL method. In this paper we present application of the "comet assay" (Single Cell Gel Electrophoresis for detection of nDNA degradation in studies of PCD during plant life cycle. We analyzed three types of tissue: anther tapetum, endosperm and mesophyll which were prepared in different ways to obtain a suspension of viable cells (without cell walls. The comet assay gives a possibility of examination of the nDNA degradation in individual cell. This method is significant for studies of the plant tissue differentiation and senescence especially in the cases when it is not possible to isolate large number of cells at the same developmental stage.

  6. In vitro assays for predicting tumor cell response to radiation by apoptotic pathways

    International Nuclear Information System (INIS)

    Algan, Oe.; Hanks, G.E.; Biade, S.; Chapman, J.D.

    1995-01-01

    Purpose: We had previously shown that the rate of spontaneous and radiation-induced apoptosis was significantly greater in well-differentiated compared to anaplastic Dunning prostate carcinomas. The goal of this study was to define the most useful assay for quantifying radiation-induced apoptotic cell death and to determine if measured rates of radiation-induced apoptosis in tumor cell populations can predict treatment outcome. Materials and Methods: The time course and extent of radiation-induced apoptosis after single doses of Cesium-137 gamma-rays were measured by five different assays. These included gross DNA degradation, nucleosome ladder formation, labeling of 3'-OH ends in DNA with an immunofluorescence probe, immunofluorescence vital stains (LIVE/DEAD[reg] EUKOLIGHT TM ) and trypan blue. The majority of these studies were performed with DU-145 human prostate cells. Data was analyzed to determine the component of cell inactivation resulting from apoptosis with the modified linear quadratic equation, -1n (SF) = (α a + α p ) D + β p D 2 , were α a represents cell inactivation by radiation-induced apoptosis, α p and β p represent cell death by proliferative mechanisms and D represents radiation dose. Results: These studies indicated that DU-145 cell death after radiation occurs over two distinct time periods. The first phase of death begins shortly after irradiation and plateaus within 16-24 hr. This process of cell death has properties consistent with apoptosis as determined by 3'-OH DNA end-labeling and nucleosome ladder assays. The second phase of cell death (determined by viability staining) begins approximately 48 hr after irradiation and continues until the remainder of inactivated cells express their death. This longer phase of cell inactivation probably represents proliferative cell death and other non-apoptotic mechanisms. The five different assays were performed on DU-145 cells 24 hr after irradiation with 10 Gy. Significant nucleosome ladders

  7. A single-loop recombinant pseudotyped-virus-based assay to detect HIV-1 phenotypic resistance.

    Science.gov (United States)

    Wu, Shouli; Yan, Pingping; Yan, Yansheng; Qiu, Lijun; Xie, Meirong

    2015-06-01

    HIV/AIDS is a leading public health concern throughout the world. Currently, treatment of HIV/AIDS still depends on highly active antiretroviral therapy (HAART); however, there is increasing evidence showing the emergence of resistance to antiretroviral drugs in HIV-1 strains, making ART less effective over time. Intensive monitoring of HIV-1 drug resistance is therefore of great importance to evaluate the current sensitivity of antiretroviral agents and is urgently needed. The aim of this study was to develop a single-loop recombinant pseudotyped-virus-based assay to detect phenotypic resistance in clinical HIV-1 strains. HIV-1 RNA was extracted from HIV-1-infected human plasma samples, and an approximately 3-kb fragment containing p7/p1/p6 cleavage sites and full-length protease (PR), reverse transcriptase (RT), thermonuclease (TNase), and integrase (1-280 aa) genes was amplified by nested RT-PCR. A retroviral vector was constructed using the HIV-1 infectious molecular clone pLWJ to test antiretroviral drug susceptibility. pLWJ-SV40-Luc contained a luciferase expression cassette inserted within a deleted region of the envelope (env) gene as an indicator gene. Resistance test vectors (RTVs) were constructed by incorporating amplified target genes into pLWJ-SV40-Luc by using ApaI or AgeI and AarI restriction sites and conventional cloning methods. The virus stocks used for drug susceptibility test were produced by co-transfecting 293T cells with RTVs and a plasmid that provided vesicular stomatitis virus glycoprotein (VSV-G). Viral replication was monitored by measuring luciferase activity in infected target cells at approximately 48 h postinfection. A total of 35 clinical plasma samples from HIV-1-infected humans were tested, and target fragments were successfully amplified from 34 samples (97.1 %) and 33 RTVs were successfully constructed by directional cloning, with an overall success rate of 94.3 %. A clear-cut dose-dependent relationship was detected between

  8. A single quantum dot-based biosensor for DNA point mutation assay.

    Science.gov (United States)

    Tang, Wei; Zhu, Guichi; Liang, Li; Zhang, Chun-Yang

    2015-09-07

    Sensitive and selective detection of point mutation is essential to molecular biology research and early clinical diagnosis. Here, we demonstrate a single quantum dot (QD)-based biosensor for DNA point mutation assay. In this assay, a mutant target (G/C) remains unchanged after the endonuclease treatment, and the polymerase chain reaction (PCR) may be initiated with the assistance of primers and polymerase, generating a large number of mutant targets. The amplified mutant targets can be captured by biotinylated probes during the process of denaturation and annealing, and Cy5-dGTP may be assembled into the biotinylated probe with the catalysis of polymerase, leading to the formation of Cy5-labeled biotinylated probes. The Cy5-labeled biotinylated probes can be further assembled onto the QD surface to obtain a Cy5-DNA-QD complex, resulting in the generation of fluorescence resonance energy transfer (FRET) between the QD donor and the Cy5 receptor. The mutant targets can be quantitatively evaluated by the measurement of Cy5 counts by total internal reflection fluorescence (TIRF) microscopy. While in the presence of wild-type targets (T/A), no Cy5-dGTP can be assembled into the biotinylated probe due to the presence of a mismatch and consequently no FRET is observed. This single QD-based biosensor exhibits high sensitivity with a detection limit of 5.3 aM (or 32 copies) and can even discriminate as low as 0.01% variant frequency from the mixture of mutant targets and wild-type ones. Importantly, this biosensor can be used for genomic analysis in human lung cancer cells, and may be further applied for an early clinical diagnosis and personalized medicine.

  9. Quantitative high-resolution genomic analysis of single cancer cells.

    Directory of Open Access Journals (Sweden)

    Juliane Hannemann

    Full Text Available During cancer progression, specific genomic aberrations arise that can determine the scope of the disease and can be used as predictive or prognostic markers. The detection of specific gene amplifications or deletions in single blood-borne or disseminated tumour cells that may give rise to the development of metastases is of great clinical interest but technically challenging. In this study, we present a method for quantitative high-resolution genomic analysis of single cells. Cells were isolated under permanent microscopic control followed by high-fidelity whole genome amplification and subsequent analyses by fine tiling array-CGH and qPCR. The assay was applied to single breast cancer cells to analyze the chromosomal region centred by the therapeutical relevant EGFR gene. This method allows precise quantitative analysis of copy number variations in single cell diagnostics.

  10. Single-Tube Flow Cytometry Assay for the Detection of Mature Lymphoid Neoplasms in Paucicellular Samples.

    Science.gov (United States)

    Stacchini, Alessandra; Demurtas, Anna; Aliberti, Sabrina; Barreca, Antonella; Novero, Domenico; Pacchioni, Donatella

    2016-01-01

    Flow cytometry (FC) has become a useful support for cytomorphologic evaluation (CM) of fine-needle aspirates (FNA) and serous cavity effusions (SCE) in cases of suspected non-Hodgkin lymphoma (NHL). FC results may be hampered by the scarce viability and low cellularity of the specimens. We developed a single-tube FC assay (STA) that included 10 antibodies cocktailed in 8-color labeling, a cell viability dye, and a logical gating strategy to detect NHL in hypocellular samples. The results were correlated with CM and confirmed by histologic or molecular data when available. Using the STA, we detected B-type NHL in 31 out of 103 hypocellular samples (81 FNA and 22 SCE). Of these, 8 were not confirmed by CM and 2 were considered to be only suspicious. The FC-negative samples had a final diagnosis of benign/reactive process (42/72), carcinoma (27/72), or Hodgkin lymphoma (3/72). The STA approach allowed obtainment of maximum immunophenotyping data in specimens containing a low number of cells and a large amount of debris. The information obtained by STA can help cytomorphologists not only to recognize but also to exclude malignant lymphomas. © 2016 S. Karger AG, Basel.

  11. Single-cell mechanics: the parallel plates technique.

    Science.gov (United States)

    Bufi, Nathalie; Durand-Smet, Pauline; Asnacios, Atef

    2015-01-01

    We describe here the parallel plates technique which enables quantifying single-cell mechanics, either passive (cell deformability) or active (whole-cell traction forces). Based on the bending of glass microplates of calibrated stiffness, it is easy to implement on any microscope, and benefits from protocols and equipment already used in biology labs (coating of glass slides, pipette pullers, micromanipulators, etc.). We first present the principle of the technique, the design and calibration of the microplates, and various surface coatings corresponding to different cell-substrate interactions. Then we detail the specific cell preparation for the assays, and the different mechanical assays that can be carried out. Finally, we discuss the possible technical simplifications and the specificities of each mechanical protocol, as well as the possibility of extending the use of the parallel plates to investigate the mechanics of cell aggregates or tissues. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Single and 30 fraction tumor control doses correlate in xenografted tumor models: implications for predictive assays

    International Nuclear Information System (INIS)

    Gerweck, Leo E.; Dubois, Willum; Baumann, Michael; Suit, Herman D.

    1995-01-01

    Purpose/Objective: In a previous publication we reported that laboratory assays of tumor clonogen number, in combination with intrinsic radiosensitivity measured in-vitro, accurately predicted the rank-order of single fraction 50% tumor control doses, in six rodent and xenografted human tumors. In these studies, tumor hypoxia influenced the absolute value of the tumor control doses across tumor types, but not their rank-order. In the present study we hypothesize that determinants of the single fraction tumor control dose, may also strongly influence the fractionaled tumor control doses, and that knowledge of tumor clonogen number and their sensitivity to fractionated irradiation, may be useful for predicting the relative sensitivity of tumors treated by conventional fractionated irradiation. Methods/Materials: Five tumors of human origin were used for these studies. Special care was taken to ensure that all tumor control dose assays were performed over the same time frame, i.e., in-vitro cells of a similar passage were used to initiate tumor sources which were expanded and used in the 3rd or 4th generation. Thirty fraction tumor control doses were performed in air breathing mice, under normal blood flow conditions (two fractions/day). The results of these studies have been previously published. For studies under uniformly (clamp) hypoxic conditions, tumors arising from the same transplantation were randomized into single or fractionated dose protocols. For estimation of the fractionated TCD50 under hypoxic conditions, tumors were exposed to six 5.4 Gy fractions (∼ 2 Gy equivalent under air), followed by graded 'top-up' dose irradiation for determination of the TCD50; the time interval between doses was 6-9 hours. The single dose equivalent of the six 5.4 Gy doses was used to calculate an extrapolated 30 fraction hypoxic TCD50. Results: Fractionation substantially increased the dose required for tumor control in 4 of the 5 tumors investigated. For these 4 tumors

  13. Radiopeptide internalisation and externalization assays: cell viability and radioligand integrity.

    Science.gov (United States)

    Naqvi, Syed Ali Raza; Sosabowski, Jane K; Nagra, Saeed Ahamad; Ishfaq, Malik M; Mather, Stephen J; Matzow, Torkjel

    2011-01-01

    Various aspects of radiopeptide receptor-mediated cell internalisation and externalization assays were assessed, including the integrity of externalized peptides and the effect of varying the pH and incubation time of the acid wash step (to remove surface receptor-bound ligand) on efficacy and cell viability. The observed intact proportion of externalized peptide was 5-10%, and acid wash buffers with pH 2.8 or below were found to be detrimental to cell viability and integrity, particularly following prolonged incubation times. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Radiopeptide internalisation and externalisation assays: Cell viability and radioligand integrity

    International Nuclear Information System (INIS)

    Raza Naqvi, Syed Ali; Sosabowski, Jane K.; Ahamad Nagra, Saeed; Ishfaq, Malik M.; Mather, Stephen J.; Matzow, Torkjel

    2011-01-01

    Various aspects of radiopeptide receptor-mediated cell internalisation and externalisation assays were assessed, including the integrity of externalised peptides and the effect of varying the pH and incubation time of the acid wash step (to remove surface receptor-bound ligand) on efficacy and cell viability. The observed intact proportion of externalised peptide was 5-10%, and acid wash buffers with pH 2.8 or below were found to be detrimental to cell viability and integrity, particularly following prolonged incubation times.

  15. A data comparison between a traditional and the single-step β-galactosidase assay

    Directory of Open Access Journals (Sweden)

    Jorrit Schaefer

    2016-09-01

    Full Text Available This article describes reproducibility of a single-step automated β-galactosidase, and the equivalence of its data to the traditional assay (“Experiments in Molecular Genetics” [1]. This was done via a pairwise comparison of both methods using strains with Miller Unit [MU] values ranging from 0 to over 2000. The data presented in this article is associated with the research article entitled “A single-step method for mid to high throughput β-galactosidase assays in Escherichia coli using a microplate reader” [2].

  16. Single-cell analysis of growth and cell division of the anaerobe Desulfovibrio vulgaris Hildenborough

    Directory of Open Access Journals (Sweden)

    Anouchka eFievet

    2015-12-01

    Full Text Available Recent years have seen significant progress in understanding basic bacterial cell cycle properties such as cell growth and cell division. While characterization and regulation of bacterial cell cycle is quite well documented in the case of fast growing aerobic model organisms, no data has been so far reported for anaerobic bacteria. This lack of information in anaerobic microorganisms can mainly be explained by the absence of molecular and cellular tools such as single cell microscopy and fluorescent probes usable for anaerobes and essential to study cellular events and/or subcellular localization of the actors involved in cell cycle.In this study, single-cell microscopy has been adapted to study for the first time, in real time, the cell cycle of a bacterial anaerobe, Desulfovibrio vulgaris Hildenborough (DvH. This single-cell analysis provides mechanistic insights into the cell division cycle of DvH, which seems to be governed by the recently discussed so-called incremental model that generates remarkably homogeneous cell sizes. Furthermore, cell division was reversibly blocked during oxygen exposure. This may constitute a strategy for anaerobic cells to cope with transient exposure to oxygen that they may encounter in their natural environment, thereby contributing to their aerotolerance. This study lays the foundation for the first molecular, single-cell assay that will address factors that cannot otherwise be resolved in bulk assays and that will allow visualization of a wide range of molecular mechanisms within living anaerobic cells.

  17. Isolation of Treg cells and Treg cell suppression/death assay

    OpenAIRE

    sprotocols

    2015-01-01

    In vitro Treg suppression assays are performed to determine the functional effect of Treg cells on CD4 T cells. They are performed by co-culturing the responding population (Tresp) with the Treg cells or control CD4 cells (Tcon cells).

  18. Cell assay using a two-photon-excited europium chelate.

    Science.gov (United States)

    Xiao, Xudong; Haushalter, Jeanne P; Kotz, Kenneth T; Faris, Gregory W

    2011-08-01

    We report application of two-photon excitation of europium chelates to immunolabeling of epidermal growth factor receptor (EGFR) cell surface proteins on A431 cancer cells. The europium chelates are excited with two photons of infrared light and emit in the visible. Europium chelates are conjugated to antibodies for EGFR. A431 (human epidermoid carcinoma) cells are labeled with this conjugate and imaged using a multiphoton microscope. To minimize signal loss due to the relatively long-lived Eu(3+) emission, the multiphoton microscope is used with scanning laser two-photon excitation and non-scanning detection with a CCD. The chelate labels show very little photobleaching (less than 1% during continuous illumination in the microscope for 20 minutes) and low levels of autofluorescence (less than 1% of the signal from labeled cells). The detection limit of the europium label in the cell assay is better than 100 zeptomoles.

  19. Expression of assayable residual stem cell damage in erythroid differentiation

    International Nuclear Information System (INIS)

    Huebner, G.E.; Miller, M.E.; Cronkite, E.P.

    1985-01-01

    In rodents, residual damage is inducible in hematopoietic stem cells by exposure to ionizing radiation or alkylating agents. This damage can b e assayed in mice by transferring bone marrow into lethally irradiated syngeneic recipients and subsequently measuring the incremental increase of-( 125 I)iodo-2'-deoxyuridine incorporation in spleens. In this study, bone marrow from mice treated 3 weeks previously with Methylnitrosourea (50 mg/kg) or 450 rad was injected into recipients in order to determine possible residual effects of treatment of erythroid cell differentiation following stem cell seeding. Such effects were detected by a reduced amount of 59 Fe incorporation into spleens, thus indicatin g transfer of residual stem cell damage to differentiating cells. (orig.)

  20. An improved method for staining cell colonies in clonogenic assays.

    Science.gov (United States)

    Guda, Kishore; Natale, Leanna; Markowitz, Sanford D

    2007-06-01

    Clonogenic assay is a widely used experimental approach to test for the effects of drugs/genes on the growth and proliferative characteristics of cells in vitro. Accurate quantitation of treatment effects in clonogeneic assays depends on the ability to visualize and count cell colonies precisely. We report a novel method (referred as ETeB) for staining cell colonies grown on plastic and specially coated substrates like collagen. Using colon cancer cell lines grown on plastic and collagen, we compared the colony staining efficiencies of the widely used methylene blue, and Ethidium bromide (ETeB) stains. Results show that the ETeB protocol works well on plastic and is extremely effective for staining colonies on collagen when compared to methylene blue. The key features and advantages of ETeB technique are; (a) reduction in background for colonies grown on collagen and possibly other substrates, (b) the whole procedure takes less than a minute, (c) no post-stain washing step is required which eliminates colony losses for cell lines that are loosely adherent, (d) colony visualization and counting can be done immediately following the staining procedure using a standard UV illuminator and software, and (e) the method works across a wide variety of cell lines. The simplicity and robustness of this procedure should warrant its usage in both small and large-scale clonogenic experiments.

  1. Use of the mitochondria toxicity assay for quantifying the viable cell density of microencapsulated jurkat cells.

    Science.gov (United States)

    Werner, M; Biss, K; Jérôme, V; Hilbrig, F; Freitag, R; Zambrano, K; Hübner, H; Buchholz, R; Mahou, R; Wandrey, C

    2013-01-01

    The mitochondria toxicity assay (MTT assay) is an established method for monitoring cell viability based on mitochondrial activity. Here the MTT assay is proposed for the in situ quantification of the living cell density of microencapsulated Jurkat cells. Three systems were used to encapsulate the cells, namely a membrane consisting of an interpenetrating polyelectrolyte network of sodium cellulose sulphate/poly(diallyldimethylammonium chloride) (NaCS/PDADMAC), a calcium alginate hydrogel covered with poly(L-lysine) (Ca-alg-PLL), and a novel calcium alginate-poly(ethylene glycol) hybrid material (Ca-alg-PEG). MTT results were correlated to data obtained by the trypan blue exclusion assay after release of the cells from the NaCS/PDADMAC and Ca-alg-PLL capsules, while a resazurin-based assay was used for comparison in case of the Ca-alg-PEG material. Analysis by MTT assay allows quick and reliable determination of viable cell densities of encapsulated cells independent of the capsule material. The assay is highly reproducible with inter-assay relative standard deviations below 10%. © 2013 American Institute of Chemical Engineers.

  2. Cell invasion in the spheroid sprouting assay: a spatial organisation analysis adaptable to cell behaviour.

    Directory of Open Access Journals (Sweden)

    Silvia Blacher

    Full Text Available The endothelial cell spheroid assay provides a suitable in vitro model to study (lymph angiogenesis and test pro- and anti-(lymph angiogenic factors or drugs. Usually, the extent of cell invasion, observed through optical microscopy, is measured. The present study proposes the spatial distribution of migrated cells as a new descriptor of the (lymph angiogenic response. The utility of this novel method rests with its capacity to locally characterise spheroid structure, allowing not only the investigation of single and collective cell invasion but also the evolution of the spheroid core itself. Moreover, the proposed method can be applied to 2D-projected spheroid images obtained by optical microscopy, as well as to 3D images acquired by confocal microscopy. To validate the proposed methodology, endothelial cell invasion was evaluated under different experimental conditions. The results were compared with widely used global parameters. The comparison shows that our method prevents local spheroid modifications from being overlooked and leading to the possible misinterpretation of results.

  3. A Modified NK Cell Degranulation Assay Applicable for Routine Evaluation of NK Cell Function

    Directory of Open Access Journals (Sweden)

    Snehal Shabrish

    2016-01-01

    Full Text Available Natural killer (NK cells play important role in innate immunity against tumors and viral infections. Studies show that lysosome-associated membrane protein-1 (LAMP-1, CD107a is a marker for degranulation of NK and cytotoxic T cells and its expression is a sensitive marker for the cytotoxic activity determination. The conventional methods of determination of CD107a on NK cells involve use of peripheral blood mononuclear cells (PBMC or pure NK cells and K562 cells as stimulants. Thus, it requires large volume of blood sample which is usually difficult to obtain in pediatric patients and patients with cytopenia and also requires specialized laboratory for maintaining cell line. We have designed a flow cytometric assay to determine CD107a on NK cells using whole blood, eliminating the need for isolation of PBMC or isolate NK cells. This assay uses phorbol-12-myristate-13-acetate (PMA and calcium ionophore (Ca2+-ionophore instead of K562 cells for stimulation and thus does not require specialized cell culture laboratory. CD107a expression on NK cells using modified NK cell degranulation assay compared to the conventional assay was significantly elevated (p<0.0001. It was also validated by testing patients diagnosed with familial hemophagocytic lymphohistiocytosis (FHL with defect in exocytosis. This assay is rapid, cost effective, and reproducible and requires significantly less volume of blood which is important for clinical evaluation of NK cells.

  4. A dual-mode single-molecule fluorescence assay for the detection of expanded CGG repeats in Fragile X syndrome.

    Science.gov (United States)

    Cannon, Brian; Pan, Cynthia; Chen, Liangjing; Hadd, Andrew G; Russell, Rick

    2013-01-01

    Fragile X syndrome is the leading cause of inherited mental impairment and is associated with expansions of CGG repeats within the FMR1 gene. To detect expanded CGG repeats, we developed a dual-mode single-molecule fluorescence assay that allows acquisition of two parallel, independent measures of repeat number based on (1) the number of Cy3-labeled probes bound to the repeat region and (2) the physical length of the electric field-linearized repeat region, obtained from the relative position of a single Cy5 dye near the end of the repeat region. Using target strands derived from cell-line DNA with defined numbers of CGG repeats, we show that this assay can rapidly and simultaneously measure the repeats of a collection of individual sample strands within a single field of view. With a low occurrence of false positives, the assay differentiated normal CGG repeat lengths (CGG( N ), N = 23) and expanded CGG repeat lengths (CGG( N ), N = 118), representing a premutation disease state. Further, mixtures of these DNAs gave results that correlated with their relative populations. This strategy may be useful for identifying heterozygosity or for screening collections of individuals, and it is readily adaptable for screening other repeat disorders.

  5. Genotoxicity of complex mixtures: CHO cell mutagenicity assay

    Energy Technology Data Exchange (ETDEWEB)

    Frazier, M.E.; Samuel, J.E.

    1985-02-01

    A Chinese hamster ovary (CHO) mammalian cell assay was used to evaluate the genotoxicity of complex mixtures (synthetic fuels). The genotoxicity (mutagenic potency) of the mixtures increased as the temperature of their boiling range increased. Most of the genotoxicity in the 750/sup 0/F+ boiling-range materials was associated with the neutral polycyclic aromatic hydrocarbon (PAH) fractions. Chemical analysis data indicate that the PAH fractions of high-boiling coal liquids contain a number of known chemical carcinogens, including five- and six-ring polyaromatics (e.g., benzo(a)pyrene) as well as four- and five-ring alkyl-substituted PAH (e.g., methylchrysene and dimethylbenzanthracenes); concentrations are a function of boiling point (bp). In vitro genotoxicity was also detected in fractions of nitrogen-containing polyaromatic compounds, as well as in those with aliphatics of hydroxy-containing PAH. Mutagenic activity of some fractions was detectable in the CHO assay in the absence of an exogenous metabolic activation system; in some instances, addition of exogenous enzymes and cofactors inhibited expression of the direct-acting mutagenic potential of the fraction. These data indicate that the organic matrix of the chemical fraction determines whether, and to what degree, various mutagens are expressed in the CHO assay. Therefore, the results of biological assays of these mixtures must be correlated with chemical analyses for proper interpretation of these data. 29 references, 16 figures, 4 tables.

  6. [Safety Evaluation of Rare Sugar Syrup: Single-dose Oral Toxicity in Rats, Reverse Mutation Assay, Chromosome Aberration Assay, and Acute Non-Effect Level for Diarrhea of a Single Dose in Humans].

    Science.gov (United States)

    Yamada, Takako; Iida, Tetsuo; Takamine, Satoshi; Hayashi, Noriko; Okuma, Kazuhiro

    2015-01-01

    The safety of rare sugar syrup obtained from high-fructose corn syrup under slightly alkaline conditions was studied. Mutagenicity of rare sugar syrup was assessed by a reverse mutation assay using Salmonella typhimurium and Escherichia coli, and an in vitro chromosomal aberration assay using Chinese hamster lung cell line (CHL/IU). No mutagenicity of rare sugar syrup was detected under these experimental conditions. Oral administration of single dose (15,000 mg/kg) of rare sugar syrup to rats caused no abnormalities, suggesting no adverse effect of rare sugar syrup. In humans, the acute non-effect level of rare sugar syrup for causing diarrhea was estimated as 0.9 g/kg body weight as dry solid base in both males and females.

  7. Response of CEDIA amphetamines assay after a single dose of bitter orange.

    Science.gov (United States)

    Nguyen, DiemThuy T; Bui, Linda T; Ambrose, Peter J

    2006-04-01

    Bitter orange has recently been substituted as an ingredient in many "ephedra-free" dietary supplements used for weight loss. The primary active ingredient in bitter orange is synephrine. Previous reports have documented false-positive results from ephedrine with urine amphetamine assays. Because of the similarity in chemical structure of ephedrine and synephrine, it is hypothesized that ingestion of a bitter orange supplement may have the potential to cause false-positive results with urine amphetamine assays. The purpose of this study was to determine the response of the CEDIA Amphetamines Assay after ingestion of bitter orange. Six healthy adult male volunteers were administered a single oral dose of Nature's Way Bitter Orange, a 900-mg dietary supplement extract standardized to 6% synephrine. Urine specimens were collected at baseline and 3 and 6 hours post-administration. Additional urine specimens were collected from 1 subject at 9, 12, and 15 hours after administration. All specimens were analyzed by the CEDIA Amphetamines Assay. Urine specific gravity and pH also were measured. All urine specimens demonstrated a negative response to the CEDIA Amphetamines Assay. Urine specific gravity ranged from 1.007 to 1.028, and pH ranged from 5.0 to 7.0; thus, reducing the possibility that the negative results were caused by diluted specimens or reduced excretion of synephrine into alkaline urine. This information will be of value when health care providers or those who interpret drug screens are asked to provide consultation regarding the interference of bitter orange supplements with the CEDIA Amphetamines Assay. A single-dose of Nature's Way Bitter Orange was not found to cause a false-positive response to the CEDIA Amphetamines Assay in 6 healthy adult male volunteers.

  8. The Single-Molecule Centroid Localization Algorithm Improves the Accuracy of Fluorescence Binding Assays.

    Science.gov (United States)

    Hua, Boyang; Wang, Yanbo; Park, Seongjin; Han, Kyu Young; Singh, Digvijay; Kim, Jin H; Cheng, Wei; Ha, Taekjip

    2018-03-13

    Here, we demonstrate that the use of the single-molecule centroid localization algorithm can improve the accuracy of fluorescence binding assays. Two major artifacts in this type of assay, i.e., nonspecific binding events and optically overlapping receptors, can be detected and corrected during analysis. The effectiveness of our method was confirmed by measuring two weak biomolecular interactions, the interaction between the B1 domain of streptococcal protein G and immunoglobulin G and the interaction between double-stranded DNA and the Cas9-RNA complex with limited sequence matches. This analysis routine requires little modification to common experimental protocols, making it readily applicable to existing data and future experiments.

  9. Discriminating Different Cancer Cells Using a Zebrafish in Vivo Assay

    Directory of Open Access Journals (Sweden)

    Pooja Pardhanani

    2011-10-01

    Full Text Available Despite the expanded understanding of tumor angiogenesis phenomenon and how it impacts cancer treatment outcomes, we have yet to develop a robust assay that can quickly, easily, and quantitatively measure tumor-induced angiogenesis. Since the zebrafish/tumor xenograft represents an emerging tool in this regard, the present study strives to capitalize on the ease, effectiveness, and the adaptability of this model to quantify tumor angiogenesis. In order to test a range of responses, we chose two different tumorigenic cell lines, the human non-small cell lung carcinoma (H1299 and the mouse lung adenocarcinoma (CL13. Non-tumorigenic 3T3-L1 cells served as negative control. The cells were grafted near to the perivitelline space of the zebrafish embryos and the angiogenic response was analyzed using whole-mount alkaline phosphatase (AP vessel staining and fluorescence microscopy. Angiogenic activity was scored based on the length and number of the newly formed ectopic vessels and the percentage of embryos with ectopic vessels. At 2 day-post-implantation, we detected a significant increase in the length and number of ectopic vessels with H1299 cell implantation compared to CL13 cell transplantation, both are higher than 3T3-L1 control. We also observed a significantly higher percentage of embryos with ectopic vessels with H1299 and CL13 transplantation compared to the 3T3-L1 control, but this parameter is not as robust and reliable as measuring the length and number of ectopic vessels. Furthermore, the systemic exposure of zebrafish embryos to an anti-angiogenesis drug (PTK 787, inhibitor of vascular endothelial growth factor receptor tyrosine kinase inhibited tumor-induced angiogenesis, suggesting that the assay can be used to evaluate anti-angiogenic drugs. This study implicates the feasibility of using zebrafish xenotransplantation to perform quantitative measurement of the angiogenic activity of cancer cells which can be further extended to

  10. Discriminating Different Cancer Cells Using a Zebrafish in Vivo Assay

    International Nuclear Information System (INIS)

    Moshal, Karni S.; Ferri-Lagneau, Karine F.; Haider, Jamil; Pardhanani, Pooja; Leung, TinChung

    2011-01-01

    Despite the expanded understanding of tumor angiogenesis phenomenon and how it impacts cancer treatment outcomes, we have yet to develop a robust assay that can quickly, easily, and quantitatively measure tumor-induced angiogenesis. Since the zebrafish/tumor xenograft represents an emerging tool in this regard, the present study strives to capitalize on the ease, effectiveness, and the adaptability of this model to quantify tumor angiogenesis. In order to test a range of responses, we chose two different tumorigenic cell lines, the human non-small cell lung carcinoma (H1299) and the mouse lung adenocarcinoma (CL13). Non-tumorigenic 3T3-L1 cells served as negative control. The cells were grafted near to the perivitelline space of the zebrafish embryos and the angiogenic response was analyzed using whole-mount alkaline phosphatase (AP) vessel staining and fluorescence microscopy. Angiogenic activity was scored based on the length and number of the newly formed ectopic vessels and the percentage of embryos with ectopic vessels. At 2 day-post-implantation, we detected a significant increase in the length and number of ectopic vessels with H1299 cell implantation compared to CL13 cell transplantation, both are higher than 3T3-L1 control. We also observed a significantly higher percentage of embryos with ectopic vessels with H1299 and CL13 transplantation compared to the 3T3-L1 control, but this parameter is not as robust and reliable as measuring the length and number of ectopic vessels. Furthermore, the systemic exposure of zebrafish embryos to an anti-angiogenesis drug (PTK 787, inhibitor of vascular endothelial growth factor receptor tyrosine kinase) inhibited tumor-induced angiogenesis, suggesting that the assay can be used to evaluate anti-angiogenic drugs. This study implicates the feasibility of using zebrafish xenotransplantation to perform quantitative measurement of the angiogenic activity of cancer cells which can be further extended to measure cancer cell

  11. Discriminating Different Cancer Cells Using a Zebrafish in Vivo Assay

    Energy Technology Data Exchange (ETDEWEB)

    Moshal, Karni S.; Ferri-Lagneau, Karine F.; Haider, Jamil; Pardhanani, Pooja; Leung, TinChung, E-mail: tleung@nccu.edu [Biomedical/Biotechnology Research Institute, North Carolina Central University, North Carolina Research Campus, Nutrition Research Center, 500 Laureate Way, Kannapolis, NC 28081 (United States)

    2011-10-31

    Despite the expanded understanding of tumor angiogenesis phenomenon and how it impacts cancer treatment outcomes, we have yet to develop a robust assay that can quickly, easily, and quantitatively measure tumor-induced angiogenesis. Since the zebrafish/tumor xenograft represents an emerging tool in this regard, the present study strives to capitalize on the ease, effectiveness, and the adaptability of this model to quantify tumor angiogenesis. In order to test a range of responses, we chose two different tumorigenic cell lines, the human non-small cell lung carcinoma (H1299) and the mouse lung adenocarcinoma (CL13). Non-tumorigenic 3T3-L1 cells served as negative control. The cells were grafted near to the perivitelline space of the zebrafish embryos and the angiogenic response was analyzed using whole-mount alkaline phosphatase (AP) vessel staining and fluorescence microscopy. Angiogenic activity was scored based on the length and number of the newly formed ectopic vessels and the percentage of embryos with ectopic vessels. At 2 day-post-implantation, we detected a significant increase in the length and number of ectopic vessels with H1299 cell implantation compared to CL13 cell transplantation, both are higher than 3T3-L1 control. We also observed a significantly higher percentage of embryos with ectopic vessels with H1299 and CL13 transplantation compared to the 3T3-L1 control, but this parameter is not as robust and reliable as measuring the length and number of ectopic vessels. Furthermore, the systemic exposure of zebrafish embryos to an anti-angiogenesis drug (PTK 787, inhibitor of vascular endothelial growth factor receptor tyrosine kinase) inhibited tumor-induced angiogenesis, suggesting that the assay can be used to evaluate anti-angiogenic drugs. This study implicates the feasibility of using zebrafish xenotransplantation to perform quantitative measurement of the angiogenic activity of cancer cells which can be further extended to measure cancer cell

  12. Comparison of two rapid assays for Clostridium difficile Common antigen and a C difficile toxin A/B assay with the cell culture neutralization assay.

    Science.gov (United States)

    Reller, Megan E; Alcabasa, Romina C; Lema, Clara A; Carroll, Karen C

    2010-01-01

    We compared 3 rapid assays for Clostridium difficile with a cell culture cytotoxicity neutralization assay (CCNA). Of 600 stool samples, 46 were positive for toxigenic C difficile. Both rapid common antigen assays were highly sensitive (91.3%-100%) and, therefore, were appropriate screening tests. The rapid toxin assay had poor sensitivity (61%) but excellent specificity (99.3%). Testing stools for glutamate dehydrogenase (step 1) and those positive with a rapid toxin assay (step 2) would correctly classify 81% of submitted specimens within 2 hours, including during periods of limited staffing (evenings, nights, and weekends). CCNA could then be used as a third step to test rapid toxin-negative samples, thereby providing a final result for the remaining 19% of samples by 48 to 72 hours. The use of rapid assays as outlined could enhance timely diagnosis of C difficile.

  13. Single-cell Western blotting after whole-cell imaging to assess cancer chemotherapeutic response.

    Science.gov (United States)

    Kang, Chi-Chih; Lin, Jung-Ming G; Xu, Zhuchen; Kumar, Sanjay; Herr, Amy E

    2014-10-21

    Intratumor heterogeneity remains a major obstacle to effective cancer therapy and personalized medicine. Current understanding points to differential therapeutic response among subpopulations of tumor cells as a key challenge to successful treatment. To advance our understanding of how this heterogeneity is reflected in cell-to-cell variations in chemosensitivity and expression of drug-resistance proteins, we optimize and apply a new targeted proteomics modality, single-cell western blotting (scWestern), to a human glioblastoma cell line. To acquire both phenotypic and proteomic data on the same, single glioblastoma cells, we integrate high-content imaging prior to the scWestern assays. The scWestern technique supports thousands of concurrent single-cell western blots, with each assay comprised of chemical lysis of single cells seated in microwells, protein electrophoresis from those microwells into a supporting polyacrylamide (PA) gel layer, and in-gel antibody probing. We systematically optimize chemical lysis and subsequent polyacrylamide gel electrophoresis (PAGE) of the single-cell lysate. The scWestern slides are stored for months then reprobed, thus allowing archiving and later analysis as relevant to sparingly limited, longitudinal cell specimens. Imaging and scWestern analysis of single glioblastoma cells dosed with the chemotherapeutic daunomycin showed both apoptotic (cleaved caspase 8- and annexin V-positive) and living cells. Intriguingly, living glioblastoma subpopulations show up-regulation of a multidrug resistant protein, P-glycoprotein (P-gp), suggesting an active drug efflux pump as a potential mechanism of drug resistance. Accordingly, linking of phenotype with targeted protein analysis with single-cell resolution may advance our understanding of drug response in inherently heterogeneous cell populations, such as those anticipated in tumors.

  14. Site-Specific SERS Assay for Survivin Protein Dimer: From Ensemble Experiments to Correlative Single-Particle Imaging.

    Science.gov (United States)

    Wissler, Jörg; Bäcker, Sandra; Feis, Alessandro; Knauer, Shirley K; Schlücker, Sebastian

    2017-08-01

    An assay for Survivin, a small dimeric protein which functions as modulator of apoptosis and cell division and serves as a promising diagnostic biomarker for different types of cancer, is presented. The assay is based on switching on surface-enhanced Raman scattering (SERS) upon incubation of the Survivin protein dimer with Raman reporter-labeled gold nanoparticles (AuNP). Site-specificity is achieved by complexation of nickel-chelated N-nitrilo-triacetic acid (Ni-NTA) anchors on the particle surface by multiple histidines (His 6 -tag) attached to each C-terminus of the centrosymmetric protein dimer. Correlative single-particle analysis using light sheet laser microscopy enables the simultaneous observation of both elastic and inelastic light scattering from the same sample volume. Thereby, the SERS-inactive AuNP-protein monomers can be directly discriminated from the SERS-active AuNP-protein dimers/oligomers. This information, i.e. the percentage of SERS-active AuNP in colloidal suspension, is not accessible from conventional SERS experiments due to ensemble averaging. The presented correlative single-particle approach paves the way for quantitative site-specific SERS assays in which site-specific protein recognition by small chemical and in particular supramolecular ligands can be tested. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Differentiation of drug and non-drug Cannabis using a single nucleotide polymorphism (SNP) assay.

    Science.gov (United States)

    Rotherham, D; Harbison, S A

    2011-04-15

    Cannabis sativa is both an illegal drug and a legitimate crop. The differentiation of illegal drug Cannabis from non-drug forms of Cannabis is relevant in the context of the growth of fibre and seed oil varieties of Cannabis for commercial purposes. This differentiation is currently determined based on the levels of tetrahydrocannabinol (THC) in adult plants. DNA based methods have the potential to assay Cannabis material unsuitable for analysis using conventional means including seeds, pollen and severely degraded material. The purpose of this research was to develop a single nucleotide polymorphism (SNP) assay for the differentiation of "drug" and "non-drug"Cannabis plants. An assay was developed based on four polymorphisms within a 399 bp fragment of the tetrahydrocannabinolic acid (THCA) synthase gene, utilising the snapshot multiplex kit. This SNP assay was tested on 94 Cannabis plants, which included 10 blind samples, and was able to differentiate between "drug" and "non-drug"Cannabis in all cases, while also differentiating between Cannabis and other species. Non-drug plants were found to be homozygous at the four sites assayed while drug Cannabis plants were either homozygous or heterozygous. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  16. Single Assay Detection of Acute Bee Paralysis Virus, Kashmir Bee Virus and Israeli Acute Paralysis Virus

    DEFF Research Database (Denmark)

    Francis, Roy Mathew; Kryger, Per

    2012-01-01

    A new RT-PCR primer pair designed to identify Acute Bee Paralysis Virus (ABPV), Kashmir Bee Virus (KBV) or Israeli Acute Bee Paralysis Virus (IAPV) of honey bees (Apis mellifera L.) in a single assay is described. These primers are used to screen samples for ABPV, KBV, or IAPV in a single RT-PCR ......-PCR reaction saving time and money. The primers are located in the predicted overlapping gene (pog/ORFX) which is highly conserved across ABPV, KBV, IAPV and other dicistroviruses of social insects. This study has also identified the first case of IAPV in Denmark....

  17. Transfection efficiency of normal and cancer cell lines and monitoring of promoter activity by single-cell bioluminescence imaging.

    Science.gov (United States)

    Horibe, Tomohisa; Torisawa, Aya; Akiyoshi, Ryutaro; Hatta-Ohashi, Yoko; Suzuki, Hirobumi; Kawakami, Koji

    2014-02-01

    The bioluminescence system (luciferase reporter assay system) is widely used to study gene expression, signal transduction and other cellular activities. Although transfection of reporter plasmid DNA to mammalian cell lines is an indispensable experimental step, the transfection efficiency of DNA varies among cell lines, and several cell lines are not suitable for this type of assay because of the low transfection efficiency. In this study, we confirm the transfection efficiency of reporter DNA to several cancer and normal cell lines after transient transfection by single-cell imaging. Luminescence images could be obtained from living single cells after transient transfection, and the calculated transfection efficiency of this method was similar to that of the conventional reporter assay using a luminometer. We attempted to measure the activity of the Bip promoter under endoplasmic reticulum stress conditions using both high and low transfection efficiency cells for plasmid DNA at the single-cell level, and observed activation of this promoter even in cells with the lowest transfection efficiency. These results show that bioluminescence imaging of single cells is a powerful tool for the analysis of gene expression based on a reporter assay using limited samples such as clinical specimens or cells from primary culture, and could provide additional information compared with the conventional assay. Copyright © 2013 John Wiley & Sons, Ltd.

  18. An automated cell-counting algorithm for fluorescently-stained cells in migration assays

    Directory of Open Access Journals (Sweden)

    Novielli Nicole M

    2011-10-01

    Full Text Available Abstract A cell-counting algorithm, developed in Matlab®, was created to efficiently count migrated fluorescently-stained cells on membranes from migration assays. At each concentration of cells used (10,000, and 100,000 cells, images were acquired at 2.5 ×, 5 ×, and 10 × objective magnifications. Automated cell counts strongly correlated to manual counts (r2 = 0.99, P

  19. Epigenetics reloaded: the single-cell revolution.

    Science.gov (United States)

    Bheda, Poonam; Schneider, Robert

    2014-11-01

    Mechanistically, how epigenetic states are inherited through cellular divisions remains an important open question in the chromatin field and beyond. Defining the heritability of epigenetic states and the underlying chromatin-based mechanisms within a population of cells is complicated due to cell heterogeneity combined with varying levels of stability of these states; thus, efforts must be focused toward single-cell analyses. The approaches presented here constitute the forefront of epigenetics research at the single-cell level using classic and innovative methods to dissect epigenetics mechanisms from the limited material available in a single cell. This review further outlines exciting future avenues of research to address the significance of epigenetic heterogeneity and the contributions of microfluidics technologies to single-cell isolation and analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Single-cell sequencing in stem cell biology.

    Science.gov (United States)

    Wen, Lu; Tang, Fuchou

    2016-04-15

    Cell-to-cell variation and heterogeneity are fundamental and intrinsic characteristics of stem cell populations, but these differences are masked when bulk cells are used for omic analysis. Single-cell sequencing technologies serve as powerful tools to dissect cellular heterogeneity comprehensively and to identify distinct phenotypic cell types, even within a 'homogeneous' stem cell population. These technologies, including single-cell genome, epigenome, and transcriptome sequencing technologies, have been developing rapidly in recent years. The application of these methods to different types of stem cells, including pluripotent stem cells and tissue-specific stem cells, has led to exciting new findings in the stem cell field. In this review, we discuss the recent progress as well as future perspectives in the methodologies and applications of single-cell omic sequencing technologies.

  1. Deconstructing stem cell population heterogeneity: Single-cell analysis and modeling approaches

    Science.gov (United States)

    Wu, Jincheng; Tzanakakis, Emmanuel S.

    2014-01-01

    Isogenic stem cell populations display cell-to-cell variations in a multitude of attributes including gene or protein expression, epigenetic state, morphology, proliferation and proclivity for differentiation. The origins of the observed heterogeneity and its roles in the maintenance of pluripotency and the lineage specification of stem cells remain unclear. Addressing pertinent questions will require the employment of single-cell analysis methods as traditional cell biochemical and biomolecular assays yield mostly population-average data. In addition to time-lapse microscopy and flow cytometry, recent advances in single-cell genomic, transcriptomic and proteomic profiling are reviewed. The application of multiple displacement amplification, next generation sequencing, mass cytometry and spectrometry to stem cell systems is expected to provide a wealth of information affording unprecedented levels of multiparametric characterization of cell ensembles under defined conditions promoting pluripotency or commitment. Establishing connections between single-cell analysis information and the observed phenotypes will also require suitable mathematical models. Stem cell self-renewal and differentiation are orchestrated by the coordinated regulation of subcellular, intercellular and niche-wide processes spanning multiple time scales. Here, we discuss different modeling approaches and challenges arising from their application to stem cell populations. Integrating single-cell analysis with computational methods will fill gaps in our knowledge about the functions of heterogeneity in stem cell physiology. This combination will also aid the rational design of efficient differentiation and reprogramming strategies as well as bioprocesses for the production of clinically valuable stem cell derivatives. PMID:24035899

  2. Assaying the binding strength of G-quadruplex ligands using single-molecule TPM experiments.

    Science.gov (United States)

    Liu, Shih-Wei; Chu, Jen-Fei; Tsai, Cheng-Ting; Fang, Hung-Chih; Chang, Ta-Chau; Li, Hung-Wen

    2013-05-15

    G-quadruplexes are stable secondary structures formed by Hoogsteen base pairing of guanine-rich single-stranded DNA sequences in the presence of monovalent cations (Na(+) or K(+)). Folded G-quadruplex (G4) structures in human telomeres have been proposed as a potential target for cancer therapy. In this study, we used single-molecule tethered particle motion (TPM) experiments to assay the binding strength of possible G4 ligands. We found that individual single-stranded DNA molecules containing the human telomeric sequence d[AGGG(TTAGGG)3] fluctuated between the folded and the unfolded states in a 10 mM Na(+) solution at 37 °C. The durations of folded and unfolded states were single-exponentially distributed, and in return the folding and unfolding rate constants were 1.68 ± 0.01 and 1.63 ± 0.03 (s(-1)), respectively. In the presence of G4 ligands, such as TMPyP4, DODCI, BMVC, and BMVPA, the unfolding rate constant decreased appreciably. In addition, combining the Cu(2+)-induced G4 unfolding and TPM assay, we showed that BMVC and TMPyP4 are better G4 stabilizers than DODCI. The capability of monitoring the fluctuation between the folded and the unfolded state of G4 DNA in real time allows the determination of both kinetic and thermodynamic parameters in a single measurement and offers a simple way to assay binding strength under various conditions. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  3. A Cell-Cell Fusion Assay to Assess Arenavirus Envelope Glycoprotein Membrane-Fusion Activity.

    Science.gov (United States)

    York, Joanne; Nunberg, Jack H

    2018-01-01

    For many viruses that enter their target cells through pH-dependent fusion of the viral and endosomal membranes, cell-cell fusion assays can provide an experimental platform for investigating the structure-function relationships that promote envelope glycoprotein membrane-fusion activity. Typically, these assays employ effector cells expressing the recombinant envelope glycoprotein on the cell surface and target cells engineered to quantitatively report fusion with the effector cell. In the protocol described here, Vero cells are transfected with a plasmid encoding the arenavirus envelope glycoprotein complex GPC and infected with the vTF7-3 vaccinia virus expressing the bacteriophage T7 RNA polymerase. These effector cells are mixed with target cells infected with the vCB21R-lacZ vaccinia virus encoding a β-galactosidase reporter under the control of the T7 promoter. Cell-cell fusion is induced upon exposure to low-pH medium (pH 5.0), and the resultant expression of the β-galactosidase reporter is quantitated using a chemiluminescent substrate. We have utilized this robust microplate cell-cell fusion assay extensively to study arenavirus entry and its inhibition by small-molecule fusion inhibitors.

  4. Parallel single-cell analysis microfluidic platform

    NARCIS (Netherlands)

    van den Brink, Floris Teunis Gerardus; Gool, Elmar; Frimat, Jean-Philippe; Bomer, Johan G.; van den Berg, Albert; le Gac, Severine

    2011-01-01

    We report a PDMS microfluidic platform for parallel single-cell analysis (PaSCAl) as a powerful tool to decipher the heterogeneity found in cell populations. Cells are trapped individually in dedicated pockets, and thereafter, a number of invasive or non-invasive analysis schemes are performed.

  5. NanoVelcro rare-cell assays for detection and characterization of circulating tumor cells.

    Science.gov (United States)

    Jan, Yu Jen; Chen, Jie-Fu; Zhu, Yazhen; Lu, Yi-Tsung; Chen, Szu Hao; Chung, Howard; Smalley, Matthew; Huang, Yen-Wen; Dong, Jiantong; Yu, Hsiao-Hua; Tomlinson, James S; Hou, Shuang; Agopian, Vatche G; Posadas, Edwin M; Tseng, Hsian-Rong

    2018-03-15

    Circulating tumor cells (CTCs) are cancer cells shredded from either a primary tumor or a metastatic site and circulate in the blood as the potential cellular origin of metastasis. By detecting and analyzing CTCs, we will be able to noninvasively monitor disease progression in individual cancer patients and obtain insightful information for assessing disease status, thus realizing the concept of "tumor liquid biopsy". However, it is technically challenging to identify CTCs in patient blood samples because of the extremely low abundance of CTCs among a large number of hematologic cells. In order to address this challenge, our research team at UCLA pioneered a unique concept of "NanoVelcro" cell-affinity substrates, in which CTC capture agent-coated nanostructured substrates were utilized to immobilize CTCs with remarkable efficiency. Four generations of NanoVelcro CTC assays have been developed over the past decade for a variety of clinical utilities. The 1st-gen NanoVelcro chips, composed of a silicon nanowire substrate (SiNS) and an overlaid microfluidic chaotic mixer, were created for CTC enumeration. The 2nd-gen NanoVelcro chips (i.e., NanoVelcro-LMD), based on polymer nanosubstrates, were developed for single-CTC isolation in conjunction with the use of the laser microdissection (LMD) technique. By grafting thermoresponsive polymer brushes onto SiNS, the 3rd-gen Thermoresponsive NanoVelcro chips have demonstrated the capture and release of CTCs at 37 and 4 °C respectively, thereby allowing for rapid CTC purification while maintaining cell viability and molecular integrity. Fabricated with boronic acid-grafted conducting polymer-based nanomaterial on chip surface, the 4th-gen NanoVelcro Chips (Sweet chip) were able to purify CTCs with well-preserved RNA transcripts, which could be used for downstream analysis of several cancer specific RNA biomarkers. In this review article, we will summarize the development of the four generations of NanoVelcro CTC Assays

  6. Automated Single Cell Data Decontamination Pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Tennessen, Kristin [Lawrence Berkeley National Lab. (LBNL), Walnut Creek, CA (United States). Dept. of Energy Joint Genome Inst.; Pati, Amrita [Lawrence Berkeley National Lab. (LBNL), Walnut Creek, CA (United States). Dept. of Energy Joint Genome Inst.

    2014-03-21

    Recent technological advancements in single-cell genomics have encouraged the classification and functional assessment of microorganisms from a wide span of the biospheres phylogeny.1,2 Environmental processes of interest to the DOE, such as bioremediation and carbon cycling, can be elucidated through the genomic lens of these unculturable microbes. However, contamination can occur at various stages of the single-cell sequencing process. Contaminated data can lead to wasted time and effort on meaningless analyses, inaccurate or erroneous conclusions, and pollution of public databases. A fully automated decontamination tool is necessary to prevent these instances and increase the throughput of the single-cell sequencing process

  7. Single-cell technologies in environmental omics

    KAUST Repository

    Kodzius, Rimantas

    2015-10-22

    Environmental studies are primarily done by culturing isolated microorganisms or by amplifying and sequencing conserved genes. Difficulties understanding the complexity of large numbers of various microorganisms in an environment led to the development of techniques to enrich specific microorganisms for upstream analysis, ultimately leading to single-cell isolation and analyses. We discuss the significance of single-cell technologies in omics studies with focus on metagenomics and metatranscriptomics. We propose that by reducing sample heterogeneity using single-cell genomics, metaomic studies can be simplified.

  8. Chemosensitivity testing of primary human renal cell carcinoma by a tetrazolium based microculture assay (MTT).

    Science.gov (United States)

    Mickisch, G; Fajta, S; Keilhauer, G; Schlick, E; Tschada, R; Alken, P

    1990-01-01

    MTT staining procedures have been used in chemosensitivity testing of established cell lines of human and other sources as well as of human leukaemias, but only limited information on its application in primary solid human tumors is presently available. We have evaluated MTT staining in primary human Renal Cell Carcinomas (RCCs), studied various factors interfering with the optimal use, and finally applied it in subsequent chemosensitivity testing. The method depends on the conversion of a water-soluble tetrazolium salt (MTT) to a purple colored formazan precipitate, a reaction effected by enzymes active only in living cells. Single cell suspensions of RCCs were obtained either by enzymatic dispersion or by mechanical dissagregation, filtered through gauze, and purified by Ficoll density centrifugation. Tests were carried out in 96-well microculture plates. 10(4) viable tumor cells per well at 4 h incubation time with 20 micrograms MTT/100 microliters total medium volume yielded best results. Formazan crystals were dissolved with DMSO, and the plates were immediately measured on a microculture plate reader at 540 nm. Under these criteria, linearity of the system could be demonstrated. For chemosensitivity testing, cells were continuously exposed to a number of drugs prior to the MTT staining procedure. Reproducibility of results was assessed and confirmed by culturing RCCs in flasks additionally, resubmitting them after 1, 2, and 4 weeks to the MTT assay. We conclude that the semiautomated MTT assay offers a valid, rapid, reliable and simple method to determine the degree of chemoresistance in primary human RCCs.

  9. Technologies for Single-Cell Isolation.

    Science.gov (United States)

    Gross, Andre; Schoendube, Jonas; Zimmermann, Stefan; Steeb, Maximilian; Zengerle, Roland; Koltay, Peter

    2015-07-24

    The handling of single cells is of great importance in applications such as cell line development or single-cell analysis, e.g., for cancer research or for emerging diagnostic methods. This review provides an overview of technologies that are currently used or in development to isolate single cells for subsequent single-cell analysis. Data from a dedicated online market survey conducted to identify the most relevant technologies, presented here for the first time, shows that FACS (fluorescence activated cell sorting) respectively Flow cytometry (33% usage), laser microdissection (17%), manual cell picking (17%), random seeding/dilution (15%), and microfluidics/lab-on-a-chip devices (12%) are currently the most frequently used technologies. These most prominent technologies are described in detail and key performance factors are discussed. The survey data indicates a further increasing interest in single-cell isolation tools for the coming years. Additionally, a worldwide patent search was performed to screen for emerging technologies that might become relevant in the future. In total 179 patents were found, out of which 25 were evaluated by screening the title and abstract to be relevant to the field.

  10. Single-experiment displacement assay for quantifying high-affinity binding by isothermal titration calorimetry.

    Science.gov (United States)

    Krainer, Georg; Keller, Sandro

    2015-04-01

    Isothermal titration calorimetry (ITC) is the gold standard for dissecting the thermodynamics of a biomolecular binding process within a single experiment. However, reliable determination of the dissociation constant (KD) from a single titration is typically limited to the range 100 μM>KD>1 nM. Interactions characterized by a lower KD can be assessed indirectly by so-called competition or displacement assays, provided that a suitable competitive ligand is available whose KD falls within the directly accessible window. However, this protocol is limited by the fact that it necessitates at least two titrations to characterize one high-affinity inhibitor, resulting in considerable consumption of both sample material and time. Here, we introduce a fast and efficient ITC displacement assay that allows for the simultaneous characterization of both a high-affinity ligand and a moderate-affinity ligand competing for the same binding site on a receptor within a single experiment. The protocol is based on a titration of the high-affinity ligand into a solution containing the moderate-affinity ligand bound to the receptor present in excess. The resulting biphasic binding isotherm enables accurate and precise determination of KD values and binding enthalpies (ΔH) of both ligands. We discuss the theoretical background underlying the approach, demonstrate its practical application to metal ion chelation, explore its potential and limitations with the aid of simulations and statistical analyses, and elaborate on potential applications to protein-inhibitor interactions. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. On-slide detection of enzymatic activities in selected single cells

    DEFF Research Database (Denmark)

    Keller, Josephine Geertsen; Tesauro, Cinzia; Coletta, Andrea

    2017-01-01

    With increasing recognition of the importance in addressing cell-to-cell heterogeneity for the understanding of complex biological systems, there is a growing need for assays capable of single cell analyses. In the current study, we describe the measurement of human topoisomerase I activity in si...

  12. Stem cell assays: Something old, something new, something borrowed : Something old, something new, something borrowed

    NARCIS (Netherlands)

    van Os, R.; Kamminga, Leonie; de Haan, G.

    2004-01-01

    Numerous assays exist that measure the function of stem cells. In this article, we review in detail the history and future of existing stem cell assays. Hematopoietic stem cells (HSCs) are historically the most well studied, but new developments in stem cell research, including the claim of stem

  13. A cell impedance measurement device for the cytotoxicity assay dependent on the velocity of supplied toxic fluid

    Science.gov (United States)

    Kang, Yoon-Tae; Kim, Min-Ji; Cho, Young-Ho

    2018-04-01

    We present a cell impedance measurement chip capable of characterizing the toxic response of cells depending on the velocity of the supplied toxic fluid. Previous impedance-based devices using a single open-top chamber have been limited to maintaining a constant supply velocity, and devices with a single closed-top chamber present difficulties in simultaneous cytotoxicity assay for varying levels of supply velocities. The present device, capable of generating constant and multiple levels of toxic fluid velocity simultaneously within a single stepwise microchannel, performs a cytotoxicity assay dependent on toxic fluid velocity, in order to find the effective velocity of toxic fluid to cells for maximizing the cytotoxic effect. We analyze the cellular toxic response of 5% ethanol media supplied to cancer cells within a toxic fluid velocity range of 0-8.3 mm s-1. We observe the velocity-dependent cell detachment rate, impedance, and death rate. We find that the cell detachment rate decreased suddenly to 2.4% at a velocity of 4.4 mm s-1, and that the change rates of cell resistance and cell capacitance showed steep decreases to 8% and 41%, respectively, at a velocity of 5.7 mm s-1. The cell death rate and impedance fell steeply to 32% at a velocity of 5.7 mm s-1. We conclude that: (1) the present device is useful in deciding on the toxic fluid velocity effective to cytotoxicity assay, since the cellular toxic response is dependent on the velocity of toxic fluid, and; (2) the cell impedance analysis facilitates a finer cellular response analysis, showing better correlation with the cell death rate, compared to conventional visual observation. The present device, capable of performing the combinational analysis of toxic fluid velocity and cell impedance, has potential for application to the fine cellular toxicity assay of drugs with proper toxic fluid velocity.

  14. Endometrial carcinoma in vitro chemosensitivity testing of single and combination chemotherapy regimens using the novel microculture kinetic apoptosis assay: implications for endometrial cancer treatment.

    Science.gov (United States)

    Ballard, Karen S; Homesley, Howard D; Hodson, Charles; Presant, Cary A; Rutledge, James; Hallquist, Allan; Perree, Mathieu

    2010-03-01

    The in vitro microculture kinetic (MiCK) apoptosis assay has been used to predict single or combination chemotherapy response in leukemia patients. This feasibility study addressed MiCK in endometrial cancer specimens. Endometrial cancer specimens from total abdominal hysterectomies were processed at a central laboratory. Single cell suspensions of viable endometrial cancer cells were plated in individual wells. Single and combination regimens were tested: combinations of doxorubicin, cisplatin, and paclitaxel and carboplatin and paclitaxel (Gynecologic Oncology Group [GOG] 209 endometrial cancer phase III trial arms) as well as single agent testing with paclitaxel, carboplatin, doxorubicin, cisplatin, ifosfamide, and vincristine (active agents in GOG trials). Apoptosis was measured continuously over 48 hours. Fifteen of nineteen patients had successful assays. The highest mean chemo sensitivity was noted in the combination of cisplatin, doxorubicin, and paclitaxel with lower mean chemosensitivity for carboplatin and paclitaxel. Combination chemotherapy had higher chemosensitivity than single drug chemotherapy. However, in 25% of patients a single drug had higher chemosensitivity than combination chemotherapy. As single agents, ifosfamide, cisplatin, and paclitaxel had the highest kinetic unit values. Using a panel of agents simulating clinical dose regimens, the MiCK assay was feasible in evaluating in vitro chemosensitivity of endometrial cancer. MiCK assay results correlated with GOG clinical trial results. However, 25% of patients might be best treated with single agent chemotherapy selected by MiCK. Ifosfamide, cisplatin, and paclitaxel appear to have high activity as single agents. MiCK may be useful in future new drug testing and individualizing endometrial cancer patient's chemotherapy management.

  15. Limitations and relative utility of screening assays to assess engineered nanoparticle toxicity in a human cell line

    International Nuclear Information System (INIS)

    Monteiro-Riviere, N.A.; Inman, A.O.; Zhang, L.W.

    2009-01-01

    Single-walled carbon nanotubes (SWCNT), fullerenes (C 60 ), carbon black (CB), nC 60 , and quantum dots (QD) have been studied in vitro to determine their toxicity in a number of cell types. Here, we report that classical dye-based assays such as MTT and neutral red (NR) that determine cell viability produce invalid results with some NM (nanomaterials) due to NM/dye interactions and/or NM adsorption of the dye/dye products. In this study, human epidermal keratinocytes (HEK) were exposed in vitro to CB, SWCNT, C 60 , nC 60 , and QD to assess viability with calcein AM (CAM), Live/Dead (LD), NR, MTT, Celltiter 96 AQueous One (96 AQ), alamar Blue (aB), Celltiter-Blue (CTB), CytoTox One TM (CTO), and flow cytometry. In addition, trypan blue (TB) was quantitated by light microscopy. Assay linearity (R 2 value) was determined with HEK plated at concentrations from 0 to 25,000 cells per well in 96-well plates. HEK were treated with serial dilutions of each NM for 24 h and assessed with each of the viability assays. TB, CAM and LD assays, which depend on direct staining of living and/or dead cells, were difficult to interpret due to physical interference of the NM with cells. Results of the dye-based assays varied a great deal, depending on the interactions of the dye/dye product with the carbon nanomaterials (CNM). Results show the optimal high throughput assay for use with carbon and noncarbon NM was 96 AQ. This study shows that, unlike small molecules, CNM interact with assay markers to cause variable results with classical toxicology assays and may not be suitable for assessing nanoparticle cytotoxicity. Therefore, more than one assay may be required when determining nanoparticle toxicity for risk assessment

  16. Evaluation of a Mouse Embryonic Stem Cell Adherent Cell Differentiation and Cytotoxicity (ACDC) assay (SOT)

    Science.gov (United States)

    The Embryonic Stem Cell Test (EST) has been used to evaluate the effects of xenobiotics using three endpoints, stem cell differentiation, stem cell viability and 3T3-cell viability. Our research goal is to establish amodel system that would evaluate chemical effects using a singl...

  17. SNaPaer: a practical single nucleotide polymorphism multiplex assay for genotyping of Pseudomonas aeruginosa.

    Science.gov (United States)

    Eusebio, Nadia; Pinheiro, Tiago; Amorim, Adelina A; Gamboa, Fernanda; Saraiva, Lucília; Gusmão, Leonor; Amorim, António; Araujo, Ricardo

    2013-01-01

    Multilocus sequence typing (MLST) represents the gold standard genotyping method in studies concerning microbial population structure, being particularly helpful in the detection of clonal relatedness. However, its applicability on large-scale genotyping is limited due to the high cost and time spent on the task. The selection of the most informative nucleotide positions simplifies genomic characterization of bacteria. A simple and informative multiplex, SNaPaer assay, was developed and genotyping of Pseudomonas aeruginosa was obtained after a single reaction of multiplex PCR amplification and mini-sequencing. This cost-effective technique allowed the analysis of a Portuguese set of isolates (n = 111) collected from three distinct hospitals and the genotyping data could be obtained in less than six hours. Point mutations were shown to be the most frequent event responsible for diversification of the Portuguese population sample. The Portuguese isolates corroborated the epidemic hypothesis for P. aeruginosa population. SNaPaer genotyping assay provided a discriminatory power of 0.9993 for P. aeruginosa, by testing in silico several hundreds of MLST profiles available online. The newly proposed assay targets less than 0.01% of the total MLST length and guarantees reproducibility, unambiguous analysis and the possibility of comparing and transferring data between different laboratories. The plasticity of the method still supports the addition of extra molecular markers targeting specific purposes/populations. SNaPaer can be of great value to clinical laboratories by facilitating routine genotyping of P. aeruginosa.

  18. Clinical relevance of HLA donor-specific antibodies detected by single antigen assay in kidney transplantation.

    Science.gov (United States)

    Caro-Oleas, José Luis; González-Escribano, María Francisca; González-Roncero, Francisco Manuel; Acevedo-Calado, María José; Cabello-Chaves, Virginia; Gentil-Govantes, Miguel Ángel; Núñez-Roldán, Antonio

    2012-03-01

    Clinical relevance of donor-specific antibodies (DSAs) detected by a single antigen Luminex virtual crossmatch in pre-transplant serum samples from patients with a negative cytotoxicity-dependent complement crossmatch is controversial. The aim of this study was to analyse the influence of a pre-transplant positive virtual crossmatch in the outcome of kidney transplantation. A total of 892 patients who received a graft from deceased donors after a negative cytotoxicity crossmatch were included. Presence of anti-human leucocyte antigen (HLA) antibodies was investigated using a Luminex screening assay and anti-HLA specificities were assigned performing a Luminex single antigen assay. Graft survival was significantly worse among patients with anti-HLA DSA compared to both patients with anti-HLA with no DSA (P = 0.001) and patients without HLA antibodies (P HLA with no DSA and no HLA antibodies patient groups were observed (P = 0.595). Influence of both anti-Class I and anti-Class II DSA was detected (P 1500 (global P > 0.05). The presence of preformed HLA DSA in transplanted patients with a negative cytotoxicity crossmatch is associated with a lower allograft survival. The detection of anti-HLA with no DSA has no influence in the graft outcome. Finally, there were no demonstrable effects of mean fluorescence intensity (MFI) values >1500 on graft survival.

  19. Screening of a Brassica napus bacterial artificial chromosome library using highly parallel single nucleotide polymorphism assays

    Science.gov (United States)

    2013-01-01

    Background Efficient screening of bacterial artificial chromosome (BAC) libraries with polymerase chain reaction (PCR)-based markers is feasible provided that a multidimensional pooling strategy is implemented. Single nucleotide polymorphisms (SNPs) can be screened in multiplexed format, therefore this marker type lends itself particularly well for medium- to high-throughput applications. Combining the power of multiplex-PCR assays with a multidimensional pooling system may prove to be especially challenging in a polyploid genome. In polyploid genomes two classes of SNPs need to be distinguished, polymorphisms between accessions (intragenomic SNPs) and those differentiating between homoeologous genomes (intergenomic SNPs). We have assessed whether the highly parallel Illumina GoldenGate® Genotyping Assay is suitable for the screening of a BAC library of the polyploid Brassica napus genome. Results A multidimensional screening platform was developed for a Brassica napus BAC library which is composed of almost 83,000 clones. Intragenomic and intergenomic SNPs were included in Illumina’s GoldenGate® Genotyping Assay and both SNP classes were used successfully for screening of the multidimensional BAC pools of the Brassica napus library. An optimized scoring method is proposed which is especially valuable for SNP calling of intergenomic SNPs. Validation of the genotyping results by independent methods revealed a success of approximately 80% for the multiplex PCR-based screening regardless of whether intra- or intergenomic SNPs were evaluated. Conclusions Illumina’s GoldenGate® Genotyping Assay can be efficiently used for screening of multidimensional Brassica napus BAC pools. SNP calling was specifically tailored for the evaluation of BAC pool screening data. The developed scoring method can be implemented independently of plant reference samples. It is demonstrated that intergenomic SNPs represent a powerful tool for BAC library screening of a polyploid genome

  20. Multiplex single nucleotide polymorphism (SNP) assay for detection of soybean mosaic virus resistance genes in soybean.

    Science.gov (United States)

    Shi, Ainong; Chen, Pengyin; Vierling, Richard; Zheng, Cuming; Li, Dexiao; Dong, Dekun; Shakiba, Ehsan; Cervantez, Innan

    2011-02-01

    Soybean mosaic virus (SMV) is one of the most destructive viral diseases in soybean (Glycine max). Three independent loci for SMV resistance have been identified in soybean germplasm. The use of genetic resistance is the most effective method of controlling this disease. Marker assisted selection (MAS) has become very important and useful in the effort of selecting genes for SMV resistance. Single nucleotide polymorphism (SNP), because of its abundance and high-throughput potential, is a powerful tool in genome mapping, association studies, diversity analysis, and tagging of important genes in plant genomics. In this study, a 10 SNPs plus one insert/deletion (InDel) multiplex assay was developed for SMV resistance: two SNPs were developed from the candidate gene 3gG2 at Rsv1 locus, two SNPs selected from the clone N11PF linked to Rsv1, one 'BARC' SNP screened from soybean chromosome 13 [linkage group (LG) F] near Rsv1, two 'BARC' SNPs from probe A519 linked to Rsv3, one 'BARC' SNP from chromosome 14 (LG B2) near Rsv3, and two 'BARC' SNPs from chromosome 2 (LG D1b) near Rsv4, plus one InDel marker from expressed sequence tag (EST) AW307114 linked to Rsv4. This 11 SNP/InDel multiplex assay showed polymorphism among 47 diverse soybean germplasm, indicating this assay can be used to investigate the mode of inheritance in a SMV resistant soybean line carrying Rsv1, Rsv3, and/or Rsv4 through a segregating population with phenotypic data, and to select a specific gene or pyramid two or three genes for SMV resistance through MAS in soybean breeding program. The presence of two SMV resistance genes (Rsv1 and Rsv3) in J05 soybean was confirmed by the SNP assay.

  1. Evaluation and validation of a single-dilution potency assay based upon serology of vaccines containing diphtheria toxoid: statistical analysis

    NARCIS (Netherlands)

    Marsman FR; Akkermans AM; Hendriksen CFM; de Jong WH

    1993-01-01

    This document presents the results of a validation study to the use of a single dilution assay in potency testing of the diphtheria component of DPT-polio vaccines. Based on historical data of multi-dilution assays on 27 consecutive batches a simulation study was performed to test the actual

  2. A versatile assay for RNA-binding proteins in living cells.

    Science.gov (United States)

    Strein, Claudia; Alleaume, Anne-Marie; Rothbauer, Ulrich; Hentze, Matthias W; Castello, Alfredo

    2014-05-01

    RNA-binding proteins (RBPs) control RNA fate from synthesis to decay. Since their cellular expression levels frequently do not reflect their in vivo activity, methods are needed to assess the steady state RNA-binding activity of RBPs as well as their responses to stimuli. While electrophoresis mobility shift assays (EMSA) have been used for such determinations, their results serve at best as proxies for the RBP activities in living cells. Here, we describe a quantitative dual fluorescence method to analyze protein-mRNA interactions in vivo. Known or candidate RBPs are fused to fluorescent proteins (eGFP, YFP), expressed in cells, cross-linked in vivo to RNA by ultraviolet light irradiation, and immunoprecipitated, after lysis, with a single chain antibody fragment directed against eGFP (GFP-binding protein, GBP). Polyadenylated RNA-binding activity of fusion proteins is assessed by hybridization with an oligo(DT) probe coupled with a red fluorophore. Since UV light is directly applied to living cells, the assay can be used to monitor dynamic changes in RNA-binding activities in response to biological or pharmacological stimuli. Notably, immunoprecipitation and hybridization can also be performed with commercially available GBP-coupled 96-well plates (GFP-multiTrap), allowing highly parallel RNA-binding measurements in a single experiment. Therefore, this method creates the possibility to conduct in vivo high-throughput RNA-binding assays. We believe that this fast and simple radioactivity-free method will find many useful applications in RNA biology.

  3. Isolation and functional interrogation of adult human prostate epithelial stem cells at single cell resolution

    Directory of Open Access Journals (Sweden)

    Wen-Yang Hu

    2017-08-01

    Full Text Available Using primary cultures of normal human prostate epithelial cells, we developed a novel prostasphere-based, label-retention assay that permits identification and isolation of stem cells at a single cell level. Their bona fide stem cell nature was corroborated using in vitro and in vivo regenerative assays and documentation of symmetric/asymmetric division. Robust WNT10B and KRT13 levels without E-cadherin or KRT14 staining distinguished individual stem cells from daughter progenitors in spheroids. Following FACS to isolate label-retaining stem cells from label-free progenitors, RNA-seq identified unique gene signatures for the separate populations which may serve as useful biomarkers. Knockdown of KRT13 or PRAC1 reduced sphere formation and symmetric self-renewal highlighting their role in stem cell maintenance. Pathways analysis identified ribosome biogenesis and membrane estrogen-receptor signaling enriched in stem cells with NF-ĸB signaling enriched in progenitors; activities that were biologically confirmed. Further, bioassays identified heightened autophagy flux and reduced metabolism in stem cells relative to progenitors. These approaches similarly identified stem-like cells from prostate cancer specimens and prostate, breast and colon cancer cell lines suggesting wide applicability. Together, the present studies isolate and identify unique characteristics of normal human prostate stem cells and uncover processes that maintain stem cell homeostasis in the prostate gland.

  4. Feasibility of drug screening with panels of human tumor cell lines using a microculture tetrazolium assay.

    Science.gov (United States)

    Alley, M C; Scudiero, D A; Monks, A; Hursey, M L; Czerwinski, M J; Fine, D L; Abbott, B J; Mayo, J G; Shoemaker, R H; Boyd, M R

    1988-02-01

    For the past 30 years strategies for the preclinical discovery and development of potential anticancer agents have been based largely upon the testing of agents in mice bearing transplantable leukemias and solid tumors derived from a limited number of murine as well as human sources. The feasibility of implementing an alternate approach, namely combined in vitro/in vivo screening for selective cytotoxicity among panels of human tumor cell lines derived from a broad spectrum of human solid tumors is under investigation. A group of 30 cell lines acquired from a variety of sources and representing 8 lung cancer pathologies as well as 76 cell lines representing 10 other categories of human cancer (carcinomas of colon, breast, kidney, prostate, ovary, head and neck; glioma; leukemia; melanoma; and sarcoma) have exhibited acceptable growth characteristics and suitable colorimetric profiles in a single, standard culture medium. Measurements of in vitro growth in microculture wells by cell-mediated reduction of tetrazolium showed excellent correlation (0.89 less than r2 less than 0.98) with measurements of cellular protein in adherent cell line cultures as well as viable cell count in suspension cell line cultures (0.94 less than r2 less than 0.99). Since the microculture tetrazolium assay provides sensitive and reproducible indices of growth as well as drug sensitivity in individual cell lines over the course of multiple passages and several months' cultivation, it appears suitable for initial-stage in vitro drug screening.

  5. Single lipid vesicle assay for characterizing single-enzyme kinetics of phospholipid hydrolysis in a complex biological fluid.

    Science.gov (United States)

    Tabaei, Seyed R; Rabe, Michael; Zetterberg, Henrik; Zhdanov, Vladimir P; Höök, Fredrik

    2013-09-25

    Imaging of individual lipid vesicles is used to track single-enzyme kinetics of phospholipid hydrolysis. The method is employed to quantify the catalytic activity of phospholipase A2 (PLA2) in both pure and complex biological fluids. The measurements are demonstrated to offer a subpicomolar limit of detection (LOD) of human secretory PLA2 (sPLA2) in up to 1000-fold-diluted cerebrospinal fluid (CSF). An additional new feature provided by the single-enzyme sensitivity is that information about both relative concentration variations of active sPLA2 in CSF and the specific enzymatic activity can be simultaneously obtained. When CSF samples from healthy controls and individuals diagnosed with Alzheimer's disease (AD) are analyzed, the specific enzymatic activity is found to be preserved within 7% in the different CSF samples whereas the enzyme concentration differs by up to 56%. This suggests that the previously reported difference in PLA2 activity in CSF samples from healthy and AD individuals originates from differences in the PLA2 expression level rather than from the enzyme activity. Conventional ensemble averaging methods used to probe sPLA2 activity do not allow one to obtain such information. Together with an improvement in the LOD of at least 1 order of magnitude compared to that of conventional assays, this suggests that the method will become useful in furthering our understanding of the role of PLA2 in health and disease and in detecting the pharmacodynamic effects of PLA2-targeting drug candidates.

  6. Direct microculture enzyme-linked immunosorbent assay for studying neural cells: oligodendrocytes.

    Science.gov (United States)

    Gard, A L; Warrington, A E; Pfeiffer, S E

    1988-05-01

    Oligodendrocyte development has been studied in a standardized primary microculture system initiated from day 20-21 fetal rat brain using a solid-phase enzyme-linked immunosorbent assay (ELISA) carried out directly on fixed cells (direct microculture ELISA). A highly reproducible dissociation procedure is described that allows careful control of the number of cells seeded per culture. At a seeding density of 1 x 10(5) cells/culture, up to 250 oligodendrocyte-generating microcultures consisting of 10-12% oligodendrocytes can be prepared from a single fetal rat brain, thereby permitting the simultaneous assay of multiple developmental parameters in sibling cultures. The validity of this method for quantifying myelinogenesis was established by comparing the results obtained by direct microculture ELISA with immunocytochemical counting of cells in parallel cultures. As few as 200 oligodendrocytes could be detected using a biotinylated anti-Ig and an avidin-urease conjugate detection system; CNP immunoreactivity measured by ELISA was linearly proportional to the number of immunolabeled cells between 6 and 34 days in culture; the developmental time courses of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) and myelin basic protein (MBP) expression determined by the two methods were very similar. Finally, cell suspensions were seeded at increasing dilution to determine the number of cells required to generate cultures that tested positive for oligodendrocytes by ELISA. As few as 9,000 cells were sufficient, predicting a minimum of 8,000 oligoprogenitors per 20-21 day fetal rat brain. The application of direct microculture ELISA for studying oligodendrocyte population size and myelinogenesis is discussed.

  7. The effect of stem cell proliferation regulators demonstrated with an in vitro assay.

    Science.gov (United States)

    Pragnell, I B; Wright, E G; Lorimore, S A; Adam, J; Rosendaal, M; DeLamarter, J F; Freshney, M; Eckmann, L; Sproul, A; Wilkie, N

    1988-07-01

    Spleen colony formation after transplantation of bone marrow cells into irradiated mice has been used as an assay for hematopoietic stem cells (CFU-S), but has serious limitations intrinsic to an in vivo assay. In this report we describe experiments using an in vitro clonogenic assay that is especially suitable for studies of stem cell regulation as defined growth factors and normal untreated bone marrow can be used. We have demonstrated that the colony-forming cells have proliferative properties in common with CFU-S and respond to specific proliferation regulators previously detected using the spleen colony assay.

  8. Experimental techniques for single cell and single molecule biomechanics

    International Nuclear Information System (INIS)

    Lim, C.T.; Zhou, E.H.; Li, A.; Vedula, S.R.K.; Fu, H.X.

    2006-01-01

    Stresses and strains that act on the human body can arise either from external physical forces or internal physiological environmental conditions. These biophysical interactions can occur not only at the musculoskeletal but also cellular and molecular levels and can determine the health and function of the human body. Here, we seek to investigate the structure-property-function relationship of cells and biomolecules so as to understand their important physiological functions as well as establish possible connections to human diseases. With the recent advancements in cell and molecular biology, biophysics and nanotechnology, several innovative and state-of-the-art experimental techniques and equipment have been developed to probe the structural and mechanical properties of biostructures from the micro- down to picoscale. Some of these experimental techniques include the optical or laser trap method, micropipette aspiration, step-pressure technique, atomic force microscopy and molecular force spectroscopy. In this article, we will review the basic principles and usage of these techniques to conduct single cell and single molecule biomechanics research

  9. SPONTANEOUS AND MNNG-INDUCED REVERSION OF AN EGFP CONSTRUCT IN HELA CELLS: AN ASSAY FOR OBSERVING MUTATIONS IN LIVING CELLS BY FLUORESCENT MICROSCOPY

    Science.gov (United States)

    A HeLa cell line stably expressing the Enhanced Green Fluorescence Protein (EGFP) gene, interrupted by the IVS2-654 intron, was studied without treatment and after treatment with a single standard dose of 15 ?M of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). This assay was done ...

  10. Evaluation of a Mouse Embryonic Stem Cell Adherent Cell Differentiation and Cytotoxicity (ACDC) assay (Keystone Sym)

    Science.gov (United States)

    Our goal is to establish an in vitro model system to evaluate chemical effects using a single stem cell culture technique that would improve throughput and provide quantitative markers of differentiation and cell number. To this end, we have used an adherent cell differentiation ...

  11. A new cell-based assay to evaluate myogenesis in mouse myoblast C2C12 cells

    Energy Technology Data Exchange (ETDEWEB)

    Kodaka, Manami [Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo (Japan); Yang, Zeyu [Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo (Japan); Department of Ultrasound, Shengjing Hospital of China Medical University, Shenyang (China); Nakagawa, Kentaro; Maruyama, Junichi [Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo (Japan); Xu, Xiaoyin [Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo (Japan); Department of Breast Surgery, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou (China); Sarkar, Aradhan; Ichimura, Ayana [Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo (Japan); Nasu, Yusuke [Department of Breast Surgery, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou (China); Ozawa, Takeaki [Department of Chemistry, School of Science, The University of Tokyo, Tokyo (Japan); Iwasa, Hiroaki [Department of Medical Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo (Japan); Ishigami-Yuasa, Mari [Chemical Biology Screening Center, Tokyo Medical and Dental University, Tokyo (Japan); Ito, Shigeru [Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo (Japan); Kagechika, Hiroyuki [Chemical Biology Screening Center, Tokyo Medical and Dental University, Tokyo (Japan); Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo (Japan); and others

    2015-08-15

    The development of the efficient screening system of detecting compounds that promote myogenesis and prevent muscle atrophy is important. Mouse C2C12 cells are widely used to evaluate myogenesis but the procedures of the assay are not simple and the quantification is not easy. We established C2C12 cells expressing the N-terminal green fluorescence protein (GFP) and the C-terminal GFP (GFP1–10 and GFP11 cells). GFP1–10 and GFP11 cells do not exhibit GFP signals until they are fused. The signal intensity correlates with the expression of myogenic markers and myofusion. Myogenesis-promoting reagents, such as insulin-like growth factor-1 (IGF1) and β-guanidinopropionic acid (GPA), enhance the signals, whereas the poly-caspase inhibitor, z-VAD-FMK, suppresses it. GFP signals are observed when myotubes formed by GFP1–10 cells are fused with single nuclear GFP11 cells, and enhanced by IGF1, GPA, and IBS008738, a recently-reported myogenesis-promoting reagent. Fusion between myotubes formed by GFP1–10 and GFP11 cells is associated with the appearance of GFP signals. IGF1 and GPA augment these signals, whereas NSC23766, Rac inhibitor, decreases them. The conditioned medium of cancer cells suppresses GFP signals during myogenesis and reduces the width of GFP-positive myotubes after differentiation. Thus the novel split GFP-based assay will provide the useful method for the study of myogenesis, myofusion, and atrophy. - Highlights: • C2C12 cells expressing split GFP proteins show GFP signals when mix-cultured. • The GFP signals correlate with myogenesis and myofusion. • The GFP signals attenuate under the condition that muscle atrophy is induced.

  12. A high throughput single nucleotide polymorphism multiplex assay for parentage assignment in New Zealand sheep.

    Directory of Open Access Journals (Sweden)

    Shannon M Clarke

    Full Text Available Accurate pedigree information is critical to animal breeding systems to ensure the highest rate of genetic gain and management of inbreeding. The abundance of available genomic data, together with development of high throughput genotyping platforms, means that single nucleotide polymorphisms (SNPs are now the DNA marker of choice for genomic selection studies. Furthermore the superior qualities of SNPs compared to microsatellite markers allows for standardization between laboratories; a property that is crucial for developing an international set of markers for traceability studies. The objective of this study was to develop a high throughput SNP assay for use in the New Zealand sheep industry that gives accurate pedigree assignment and will allow a reduction in breeder input over lambing. This required two phases of development--firstly, a method of extracting quality DNA from ear-punch tissue performed in a high throughput cost efficient manner and secondly a SNP assay that has the ability to assign paternity to progeny resulting from mob mating. A likelihood based approach to infer paternity was used where sires with the highest LOD score (log of the ratio of the likelihood given parentage to likelihood given non-parentage are assigned. An 84 "parentage SNP panel" was developed that assigned, on average, 99% of progeny to a sire in a problem where there were 3,000 progeny from 120 mob mated sires that included numerous half sib sires. In only 6% of those cases was there another sire with at least a 0.02 probability of paternity. Furthermore dam information (either recorded, or by genotyping possible dams was absent, highlighting the SNP test's suitability for paternity testing. Utilization of this parentage SNP assay will allow implementation of progeny testing into large commercial farms where the improved accuracy of sire assignment and genetic evaluations will increase genetic gain in the sheep industry.

  13. Cytotoxicity and genotoxicity assessment of Euphorbia hirta in MCF-7 cell line model using comet assay

    OpenAIRE

    Kwan Yuet Ping; Ibrahim Darah; Yeng Chen; Sreenivasan Sasidharan

    2013-01-01

    Objective: To evaluate the cytotoxicity and genotoxicity activity of Euphorbia hirta (E. hirta) in MCF-7 cell line model using comet assay. Methods: The cytotoxicity of E. hirta extract was investigated by employing brine shrimp lethality assay and the genotoxicity of E. hirta was assessed by using Comet assay. Results: Both toxicity tests exhibited significant toxicity result. In the comet assay, the E. hirta extract exhibited genotoxicity effects against MCF-7 DNA in a time-dependent m...

  14. Optimization of genetic analysis for single cell

    Directory of Open Access Journals (Sweden)

    hussein mouawia

    2012-03-01

    Full Text Available The molecular genetic analysis of microdissected cells by laser, a method for selecting a starting material of pure DNA or RNA uncontaminated. Our study focuses on technical pre-PCR (polymerase chain reaction for the amplification of DNA from a single cell (leukocyte isolated from human blood after laser microdissection and aims to optimize the yield of DNA extracted of this cell to be amplified without errors and provide reliable genetic analyzes. This study has allowed us to reduce the duration of cell lysis in order to perform the step of expanding genomic PEP (primer extension preamplification directly after lysis the same day and the quality of genomic amplification and eliminate purification step of the product PEP, step with a risk of contamination and risk of loss of genetic material related to manipulation. This approach has shown that the combination of at least 3 STR (short tandem repeat markers for genetic analysis of single cell improves the efficiency and accuracy of PCR and minimizes the loss of allele (allele drop out; ADO. This protocol can be applied to large scale and an effective means suitable for genetic testing for molecular diagnostic from isolated single cell (cancerous - fetal.

  15. Bioconductor workflow for single-cell RNA sequencing: Normalization, dimensionality reduction, clustering, and lineage inference.

    Science.gov (United States)

    Perraudeau, Fanny; Risso, Davide; Street, Kelly; Purdom, Elizabeth; Dudoit, Sandrine

    2017-01-01

    Novel single-cell transcriptome sequencing assays allow researchers to measure gene expression levels at the resolution of single cells and offer the unprecendented opportunity to investigate at the molecular level fundamental biological questions, such as stem cell differentiation or the discovery and characterization of rare cell types. However, such assays raise challenging statistical and computational questions and require the development of novel methodology and software. Using stem cell differentiation in the mouse olfactory epithelium as a case study, this integrated workflow provides a step-by-step tutorial to the methodology and associated software for the following four main tasks: (1) dimensionality reduction accounting for zero inflation and over dispersion and adjusting for gene and cell-level covariates; (2) cell clustering using resampling-based sequential ensemble clustering; (3) inference of cell lineages and pseudotimes; and (4) differential expression analysis along lineages.

  16. Sickle cell disease biochip: a functional red blood cell adhesion assay for monitoring sickle cell disease

    Science.gov (United States)

    ALAPAN, YUNUS; KIM, CEONNE; ADHIKARI, ANIMA; GRAY, KAYLA E.; GURKAN-CAVUSOGLU, EVREN; LITTLE, JANE A.; GURKAN, UMUT A.

    2016-01-01

    Sickle cell disease (SCD) afflicts millions of people worldwide and is associated with considerable morbidity and mortality. Chronic and acute vaso-occlusion are the clinical hallmarks of SCD and can result in pain crisis, widespread organ damage, and early movtality. Even though the molecular underpinnings of SCD were identified more than 60 years ago, there are no molecular or biophysical markers of disease severity that are feasibly measured in the clinic. Abnormal cellular adhesion to vascular endothelium is at the root of vaso-occlusion. However, cellular adhesion is not currently evaluated clinically. Here, we present a clinically applicable microfluidic device (SCD biochip) that allows serial quantitative evaluation of red blood cell (RBC) adhesion to endothelium-associated protein-immobilized microchannels, in a closed and preprocessing-free system. With the SCD biochip, we have analyzed blood samples from more than 100 subjects and have shown associations between the measured RBC adhesion to endothelium-associated proteins (fibronectin and laminin) and individual RBC characteristics, including hemoglobin content, fetal hemoglobin concentration, plasma lactate dehydrogenase level, and reticulocyte count. The SCD biochip is a functional adhesion assay, reflecting quantitative evaluation of RBC adhesion, which could be used at baseline, during crises, relative to various long-term complications, and before and after therapeutic interventions. PMID:27063958

  17. Thermoresponsive micropatterned substrates for single cell studies.

    Directory of Open Access Journals (Sweden)

    Kalpana Mandal

    Full Text Available We describe the design of micropatterned surfaces for single cell studies, based on thermoresponsive polymer brushes. We show that brushes made of poly(N-isopropylacrylamide grafted at high surface density display excellent protein and cell anti-adhesive properties. Such brushes are readily patterned at the micron scale via deep UV photolithography. A proper choice of the adhesive pattern shapes, combined with the temperature-dependent swelling properties of PNIPAM, allow us to use the polymer brush as a microactuator which induces cell detachment when the temperature is reduced below [Formula: see text]C.

  18. Phenotype classification of single cells using SRS microscopy, RNA sequencing, and microfluidics (Conference Presentation)

    Science.gov (United States)

    Streets, Aaron M.; Cao, Chen; Zhang, Xiannian; Huang, Yanyi

    2016-03-01

    Phenotype classification of single cells reveals biological variation that is masked in ensemble measurement. This heterogeneity is found in gene and protein expression as well as in cell morphology. Many techniques are available to probe phenotypic heterogeneity at the single cell level, for example quantitative imaging and single-cell RNA sequencing, but it is difficult to perform multiple assays on the same single cell. In order to directly track correlation between morphology and gene expression at the single cell level, we developed a microfluidic platform for quantitative coherent Raman imaging and immediate RNA sequencing (RNA-Seq) of single cells. With this device we actively sort and trap cells for analysis with stimulated Raman scattering microscopy (SRS). The cells are then processed in parallel pipelines for lysis, and preparation of cDNA for high-throughput transcriptome sequencing. SRS microscopy offers three-dimensional imaging with chemical specificity for quantitative analysis of protein and lipid distribution in single cells. Meanwhile, the microfluidic platform facilitates single-cell manipulation, minimizes contamination, and furthermore, provides improved RNA-Seq detection sensitivity and measurement precision, which is necessary for differentiating biological variability from technical noise. By combining coherent Raman microscopy with RNA sequencing, we can better understand the relationship between cellular morphology and gene expression at the single-cell level.

  19. Optimization of the T-cell proliferation assay in fascioliasis using a ...

    African Journals Online (AJOL)

    T-cell proliferation studies are traditionally carried out with radioactive reagents or fluorescent reagents that require measurement with advanced technology instrumentation. We attempted to calibrate the optimal conditions suitable for the use of a non-radioactive assay for the measurement of a T-cell proliferation assay in ...

  20. Detection of mandarin in orange juice by single-nucleotide polymorphism qPCR assay.

    Science.gov (United States)

    Aldeguer, Miriam; López-Andreo, María; Gabaldón, José A; Puyet, Antonio

    2014-02-15

    A dual-probe real time PCR (qPCR) DNA-based analysis was devised for the identification of mandarin in orange juice. A single nucleotide polymorphism at the trnL-trnF intergenic region of the chloroplast chromosome was confirmed in nine orange (Citrus sinensis) and thirteen commercial varieties of mandarin, including Citrus reticulata and Citrus unshiu species and a mandarin × tangelo hybrid. Two short minor-groove binding fluorescent probes targeting the polymorphic sequence were used in the dual-probe qPCR, which allowed the detection of both species in single-tube reactions. The similarity of PCR efficiencies allowed a simple estimation of the ratio mandarin/orange in the juice samples, which correlated to the measured difference of threshold cycle values for both probes. The limit of detection of the assay was 5% of mandarin in orange juice, both when the juice was freshly prepared (not from concentrate) or reconstituted from concentrate, which would allow the detection of fraudulently added mandarin juice. The possible use of the dual-probe system for quantitative measurements was also tested on fruit juice mixtures. qPCR data obtained from samples containing equal amounts of mandarin and orange juice revealed that the mandarin target copy number was approximately 2.6-fold higher than in orange juice. The use of a matrix-adapted control as calibrator to compensate the resulting C(T) bias allowed accurate quantitative measurements to be obtained. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Single cell transcriptional analysis reveals novel innate immune cell types

    Directory of Open Access Journals (Sweden)

    Linda E. Kippner

    2014-06-01

    Full Text Available Single-cell analysis has the potential to provide us with a host of new knowledge about biological systems, but it comes with the challenge of correctly interpreting the biological information. While emerging techniques have made it possible to measure inter-cellular variability at the transcriptome level, no consensus yet exists on the most appropriate method of data analysis of such single cell data. Methods for analysis of transcriptional data at the population level are well established but are not well suited to single cell analysis due to their dependence on population averages. In order to address this question, we have systematically tested combinations of methods for primary data analysis on single cell transcription data generated from two types of primary immune cells, neutrophils and T lymphocytes. Cells were obtained from healthy individuals, and single cell transcript expression data was obtained by a combination of single cell sorting and nanoscale quantitative real time PCR (qRT-PCR for markers of cell type, intracellular signaling, and immune functionality. Gene expression analysis was focused on hierarchical clustering to determine the existence of cellular subgroups within the populations. Nine combinations of criteria for data exclusion and normalization were tested and evaluated. Bimodality in gene expression indicated the presence of cellular subgroups which were also revealed by data clustering. We observed evidence for two clearly defined cellular subtypes in the neutrophil populations and at least two in the T lymphocyte populations. When normalizing the data by different methods, we observed varying outcomes with corresponding interpretations of the biological characteristics of the cell populations. Normalization of the data by linear standardization taking into account technical effects such as plate effects, resulted in interpretations that most closely matched biological expectations. Single cell transcription

  2. A miniaturized cell-based fluorescence resonance energy transfer assay for insulin-receptor activation.

    Science.gov (United States)

    Marine, Shane; Zamiara, Elize; Smith, S Todd; Stec, Erica M; McGarvey, Jeremy; Kornienko, Oleg; Jiang, Guoqiang; Wong, Kenny K; Stack, Jeffrey H; Zhang, Bei B; Ferrer, Marc; Strulovici, Berta

    2006-08-15

    This report describes the development, optimization, and implementation of a miniaturized cell-based assay for the identification of small-molecule insulin mimetics and potentiators. Cell-based assays are attractive formats for compound screening because they present the molecular targets in their cellular environment. A fluorescence resonance energy transfer (FRET) cell-based assay that measures the insulin-dependent colocalization of Akt2 fused with either cyan fluorescent protein or yellow fluorescent protein to the cellular membrane was developed. This ratiometric FRET assay was miniaturized into a robust, yet sensitive 3456-well nanoplate assay with Z' factors of approximately 0.6 despite a very small assay window (less than twofold full activation with insulin). The FRET assay was used for primary screening of a large compound collection for insulin-receptor agonists and potentiators. To prioritize compounds for further development, primary hits were tested in two additional assays, a biochemical time-resolved fluorescence resonance energy transfer assay to measure insulin-receptor phosphorylation and a translocation-based imaging assay. Results from the three assays were combined to yield 11 compounds as potential leads for the development of insulin mimetics or potentiators.

  3. A simple and novel modification of comet assay for determination of bacteriophage mediated bacterial cell lysis.

    Science.gov (United States)

    Khairnar, Krishna; Sanmukh, Swapnil; Chandekar, Rajshree; Paunikar, Waman

    2014-07-01

    The comet assay is the widely used method for in vitro toxicity testing which is also an alternative to the use of animal models for in vivo testing. Since, its inception in 1984 by Ostling and Johansson, it is being modified frequently for a wide range of application. In spite of its wide applicability, unfortunately there is no report of its application in bacteriophages research. In this study, a novel application of comet assay for the detection of bacteriophage mediated bacterial cell lysis was described. The conventional methods in bacteriophage research for studying bacterial lysis by bacteriophages are plaque assay method. It is time consuming, laborious and costly. The lytic activity of bacteriophage devours the bacterial cell which results in the release of bacterial genomic material that gets detected by ethidium bromide staining method by the comet assay protocol. The objective of this study was to compare efficacy of comet assay with different assay used to study phage mediated bacterial lysis. The assay was performed on culture isolates (N=80 studies), modified comet assay appear to have relatively higher sensitivity and specificity than other assay. The results of the study showed that the application of comet assay can be an economical, time saving and less laborious alternative to conventional plaque assay for the detection of bacteriophage mediated bacterial cell lysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Determination of radiosensitivity in established and primary squamous cell carcinoma cultures using the micronucleus assay

    Energy Technology Data Exchange (ETDEWEB)

    Champion, A.R.; Hanson, J.A.; Venables, S.E.; Gaffney, C.C. [Velindre Hospital NHS Trust, Whitchurch, Cardiff (United Kingdom). Cellular and Molecular Radiation Research Unit; McGregor, A.D. [Morriston Hospital NHS Trust, Swansea (United Kingdom). Welsh Regional Burns and Plastic Surgery Unit

    1997-03-01

    In this study, the cytokinesis-block micronucleus assay (CBMN) was used to measure radiosensitivity in three established cell lines (SCC-61, V175 and V134) and 10 primary cell cultures of squamous cell carcinoma (SCC) of the head and neck. Assessment involved optimisation of the assay to determine cytochalasin-B (CB) concentration and sampling time postirradiation. A much closer correlation between dose-response data measured in the clonogenic and micronucleus assays was found when the micronucleus assay was performed under standardised conditions for each cell line (2 {mu}g/ml CB: 48 h postirradiation) instead of predetermined optimised assay conditions. This indicates that, for these SCC cell lines, the CBMN assay may be able to predict in vitro radiosensitivity. To be of clinical use in predicting radiosensitivity, the CBMN assay also needs to be evaluated with primary cell cultures. In this study, no relationship between micronucleus frequency at 2 or 6 Gy and patient clinical outcome 12 months following surgery and radiotherapy was seen. Similarly, no association between patient outcome and tumour stage, nodal stage and histology was observed. These CBMN assay data from the primary cell cultures are presently inconclusive as a measure of patient tumour radiosensitivity. (Author).

  5. Microscopy-based Assays for High-throughput Screening of Host Factors Involved in Brucella Infection of Hela Cells.

    Science.gov (United States)

    Casanova, Alain; Low, Shyan H; Emmenlauer, Mario; Conde-Alvarez, Raquel; Salcedo, Suzana P; Gorvel, Jean-Pierre; Dehio, Christoph

    2016-08-05

    Brucella species are facultative intracellular pathogens that infect animals as their natural hosts. Transmission to humans is most commonly caused by direct contact with infected animals or by ingestion of contaminated food and can lead to severe chronic infections. Brucella can invade professional and non-professional phagocytic cells and replicates within endoplasmic reticulum (ER)-derived vacuoles. The host factors required for Brucella entry into host cells, avoidance of lysosomal degradation, and replication in the ER-like compartment remain largely unknown. Here we describe two assays to identify host factors involved in Brucella entry and replication in HeLa cells. The protocols describe the use of RNA interference, while alternative screening methods could be applied. The assays are based on the detection of fluorescently labeled bacteria in fluorescently labeled host cells using automated wide-field microscopy. The fluorescent images are analyzed using a standardized image analysis pipeline in CellProfiler which allows single cell-based infection scoring. In the endpoint assay, intracellular replication is measured two days after infection. This allows bacteria to traffic to their replicative niche where proliferation is initiated around 12 hr after bacterial entry. Brucella which have successfully established an intracellular niche will thus have strongly proliferated inside host cells. Since intracellular bacteria will greatly outnumber individual extracellular or intracellular non-replicative bacteria, a strain constitutively expressing GFP can be used. The strong GFP signal is then used to identify infected cells. In contrast, for the entry assay it is essential to differentiate between intracellular and extracellular bacteria. Here, a strain encoding for a tetracycline-inducible GFP is used. Induction of GFP with simultaneous inactivation of extracellular bacteria by gentamicin enables the differentiation between intracellular and extracellular

  6. Sulforaphane induces DNA single strand breaks in cultured human cells

    Energy Technology Data Exchange (ETDEWEB)

    Sestili, Piero, E-mail: piero.sestili@uniurb.it [Dipartimento di Scienze Biomolecolari, Via Maggetti, 21, Universita degli Studi di Urbino ' Carlo Bo' , 61029 Urbino, PU (Italy); Paolillo, Marco [Dipartimento di Scienze Biomolecolari, Via Maggetti, 21, Universita degli Studi di Urbino ' Carlo Bo' , 61029 Urbino, PU (Italy); Lenzi, Monia [Dipartimento di Farmacologia, Universita degli Studi di Bologna, Via Irnerio 48, 40126 Bologna (Italy); Colombo, Evelin; Vallorani, Luciana; Casadei, Lucia; Martinelli, Chiara [Dipartimento di Scienze Biomolecolari, Via Maggetti, 21, Universita degli Studi di Urbino ' Carlo Bo' , 61029 Urbino, PU (Italy); Fimognari, Carmela [Dipartimento di Farmacologia, Universita degli Studi di Bologna, Via Irnerio 48, 40126 Bologna (Italy)

    2010-07-07

    Sulforaphane (SFR), an isothiocyanate from cruciferous vegetables, possesses growth-inhibiting and apoptosis-inducing activities in cancer cell lines. Recently, SFR has been shown to promote the mitochondrial formation of reactive oxygen species (ROS) in human cancer cell lines. The present study was undertaken to see whether SFR-derived ROS might cause DNA damage in cultured human cells, namely T limphoblastoid Jurkat and human umbilical vein endothelial cells (HUVEC). 1-3 h treatments with 10-30 {mu}M SFR elicited intracellular ROS formation (as assayed with dihydrorhodamine, DHR, oxidation) as well as DNA breakage (as assessed with fast halo assay, FHA). These effects lacked cell-type specificity, since could be observed in both Jurkat and HUVEC. Differential-pH FHA analysis of damaged DNA showed that SFR causes frank DNA single strand breaks (SSBs); no DNA double strand breaks (DSBs) were found within the considered treatment times (up to 3 h). SFR-derived ROS were formed at the mitochondrial respiratory chain (MRC) level: indeed rotenone or myxothiazol (MRC Complex I and III inhibitors, respectively) abrogated ROS formation. Furthermore ROS were not formed in Jurkat cells pharmacologically depleted of respiring mitochondria (MRC-/Jurkat). Formation of ROS was causally linked to the induction of SSBs: indeed all the experimental conditions capable of preventing ROS formation also prevented the damage of nuclear DNA from SFR-intoxicated cells. As to the toxicological relevance of SSBs, we found that their prevention slightly but significantly attenuated SFR cytotoxicity, suggesting that high-dose SFR toxicity is the result of a complex series of events among which GSH depletion seems to play a pivotal role. In conclusion, the present study identifies a novel mechanism contributing to SFR toxicity which - since DNA damage is a prominent mechanism underlying the cytotoxic activity of established antineoplastic agents - might help to exploit the therapeutic value

  7. Sulforaphane induces DNA single strand breaks in cultured human cells

    International Nuclear Information System (INIS)

    Sestili, Piero; Paolillo, Marco; Lenzi, Monia; Colombo, Evelin; Vallorani, Luciana; Casadei, Lucia; Martinelli, Chiara; Fimognari, Carmela

    2010-01-01

    Sulforaphane (SFR), an isothiocyanate from cruciferous vegetables, possesses growth-inhibiting and apoptosis-inducing activities in cancer cell lines. Recently, SFR has been shown to promote the mitochondrial formation of reactive oxygen species (ROS) in human cancer cell lines. The present study was undertaken to see whether SFR-derived ROS might cause DNA damage in cultured human cells, namely T limphoblastoid Jurkat and human umbilical vein endothelial cells (HUVEC). 1-3 h treatments with 10-30 μM SFR elicited intracellular ROS formation (as assayed with dihydrorhodamine, DHR, oxidation) as well as DNA breakage (as assessed with fast halo assay, FHA). These effects lacked cell-type specificity, since could be observed in both Jurkat and HUVEC. Differential-pH FHA analysis of damaged DNA showed that SFR causes frank DNA single strand breaks (SSBs); no DNA double strand breaks (DSBs) were found within the considered treatment times (up to 3 h). SFR-derived ROS were formed at the mitochondrial respiratory chain (MRC) level: indeed rotenone or myxothiazol (MRC Complex I and III inhibitors, respectively) abrogated ROS formation. Furthermore ROS were not formed in Jurkat cells pharmacologically depleted of respiring mitochondria (MRC-/Jurkat). Formation of ROS was causally linked to the induction of SSBs: indeed all the experimental conditions capable of preventing ROS formation also prevented the damage of nuclear DNA from SFR-intoxicated cells. As to the toxicological relevance of SSBs, we found that their prevention slightly but significantly attenuated SFR cytotoxicity, suggesting that high-dose SFR toxicity is the result of a complex series of events among which GSH depletion seems to play a pivotal role. In conclusion, the present study identifies a novel mechanism contributing to SFR toxicity which - since DNA damage is a prominent mechanism underlying the cytotoxic activity of established antineoplastic agents - might help to exploit the therapeutic value of

  8. Polydimethylsiloxane (PDMS Sub-Micron Traps for Single-Cell Analysis of Bacteria

    Directory of Open Access Journals (Sweden)

    Dietrich Kohlheyer

    2013-10-01

    Full Text Available Microfluidics has become an essential tool in single-cell analysis assays for gaining more accurate insights into cell behavior. Various microfluidics methods have been introduced facilitating single-cell analysis of a broad range of cell types. However, the study of prokaryotic cells such as Escherichia coli and others still faces the challenge of achieving proper single-cell immobilization simply due to their small size and often fast growth rates. Recently, new approaches were presented to investigate bacteria growing in monolayers and single-cell tracks under environmental control. This allows for high-resolution time-lapse observation of cell proliferation, cell morphology and fluorescence-coupled bioreporters. Inside microcolonies, interactions between nearby cells are likely and may cause interference during perturbation studies. In this paper, we present a microfluidic device containing hundred sub-micron sized trapping barrier structures for single E. coli cells. Descendant cells are rapidly washed away as well as components secreted by growing cells. Experiments show excellent growth rates, indicating high cell viability. Analyses of elongation and growth rates as well as morphology were successfully performed. This device will find application in prokaryotic single-cell studies under constant environment where by-product interference is undesired.

  9. Single-cell Raman spectroscopy of irradiated tumour cells

    Science.gov (United States)

    Matthews, Quinn

    This work describes the development and application of a novel combination of single-cell Raman spectroscopy (RS), automated data processing, and principal component analysis (PCA) for investigating radiation induced biochemical responses in human tumour cells. The developed techniques are first validated for the analysis of large data sets (˜200 spectra) obtained from single cells. The effectiveness and robustness of the automated data processing methods is demonstrated, and potential pitfalls that may arise during the implementation of such methods are identified. The techniques are first applied to investigate the inherent sources of spectral variability between single cells of a human prostate tumour cell line (DU145) cultured in vitro. PCA is used to identify spectral differences that correlate with cell cycle progression and the changing confluency of a cell culture during the first 3-4 days after sub-culturing. Spectral variability arising from cell cycle progression is (i) expressed as varying intensities of protein and nucleic acid features relative to lipid features, (ii) well correlated with known biochemical changes in cells as they progress through the cell cycle, and (iii) shown to be the most significant source of inherent spectral variability between cells. This characterization provides a foundation for interpreting spectral variability in subsequent studies. The techniques are then applied to study the effects of ionizing radiation on human tumour cells. DU145 cells are cultured in vitro and irradiated to doses between 15 and 50 Gy with single fractions of 6 MV photons from a medical linear accelerator. Raman spectra are acquired from irradiated and unirradiated cells, up to 5 days post-irradiation. PCA is used to distinguish radiation induced spectral changes from inherent sources of spectral variability, such as those arising from cell cycle. Radiation induced spectral changes are found to correlate with both the irradiated dose and the

  10. Probing bacterial adhesion at the single-cell level

    DEFF Research Database (Denmark)

    Zeng, Guanghong; Müller, Torsten; Meyer, Rikke Louise

    Bacteria initiate attachment to surfaces with the aid of different extracellular proteins and polymeric adhesins. To quantitatively analyse the cell-cell and cell-surface interactions provided by bacterial adhesins, it is essential to go down to single cell level where cell-to-cell variation can...... be considered. We have developed a simple and versatile method to make single-cell bacterial probes for measuring single cell adhesion by force spectroscopy using atomic force microscopy (AFM). A single-cell probe was readily made by picking up a bacterial cell from a glass surface by approaching a tipless AFM...... cantilever coated with the commercial cell adhesive CellTakTM. We applied the method to study adhesion of living cells to abiotic surfaces at the single-cell level. Immobilisation of single bacterial cells to the cantilever was stable for several hours, and viability was confirmed by Live/Dead staining...

  11. Use of cryopreserved transiently transfected cells in high-throughput pregnane X receptor transactivation assay.

    Science.gov (United States)

    Zhu, Zhengrong; Puglisi, Jaime; Connors, David; Stewart, Jeremy; Herbst, John; Marino, Anthony; Sinz, Michael; O'Connell, Jonathan; Banks, Martyn; Dickinson, Kenneth; Cacace, Angela

    2007-03-01

    Cryopreserved, transiently transfected HepG2 cells were compared to freshly transfected HepG2 cells for use in a pregnane X receptor (PXR) transactivation assay. Assay performance was similar for both cell preparations; however, cryopreserved cells demonstrated less interassay variation. Validation with drugs of different PXR activation potencies and efficacies demonstrated an excellent correlation (r(2) > 0.95) between cryopreserved and fresh cells. Cryopreservation did not change the effect of known CYP3A4 inducers that have poor cell permeability, indicating that cryopreservation had little effect on membrane permeability. In addition, cryopreserved HepG2 cells did not exhibit enhanced susceptibility to cytotoxic compounds compared to transiently transfected control cells. The use of cryopreserved cells enables this assay to run with enhanced efficiency.

  12. Chip based single cell analysis for nanotoxicity assessment.

    Science.gov (United States)

    Shah, Pratikkumar; Kaushik, Ajeet; Zhu, Xuena; Zhang, Chengxiao; Li, Chen-Zhong

    2014-05-07

    Nanomaterials, because of their tunable properties and performances, have been utilized extensively in everyday life related consumable products and technology. On exposure, beyond the physiological range, nanomaterials cause health risks via affecting the function of organisms, genomic systems, and even the central nervous system. Thus, new analytical approaches for nanotoxicity assessment to verify the feasibility of nanomaterials for future use are in demand. The conventional analytical techniques, such as spectrophotometric assay-based techniques, usually require a lengthy and time-consuming process and often produce false positives, and often cannot be implemented at a single cell level measurement for studying cell behavior without interference from its surrounding environment. Hence, there is a demand for a precise, accurate, sensitive assessment for toxicity using single cells. Recently, due to the advantages of automation of fluids and minimization of human errors, the integration of a cell-on-a-chip (CoC) with a microfluidic system is in practice for nanotoxicity assessments. This review explains nanotoxicity and its assessment approaches with advantages/limitations and new approaches to overcome the confines of traditional techniques. Recent advances in nanotoxicity assessment using a CoC integrated with a microfluidic system are also discussed in this review, which may be of use for nanotoxicity assessment and diagnostics.

  13. Radiosensitivity evaluation of Human tumor cell lines by single cell gel electrophoresis

    International Nuclear Information System (INIS)

    Zhang Yipei; Cao Jia; Wang Yan; Du Liqing; Li Jin; Wang Qin; Fan Feiyue; Liu Qiang

    2011-01-01

    Objective: To explore the feasibility of determining radiosensitivity of human tumor cell lines in vitro using single cell gel electrophoresis (SCGE). Methods: Three human tumor cell lines were selected in this study, HepG 2 , EC-9706 and MCF-7. The surviving fraction (SF) and DNA damage were detected by MTT assay, nested PCR technique and comet assay respectively. Results: MTT assay: The SF of HepG 2 and EC-9706 after irradiated by 2, 4 and 8 Gy was lower significantly than that of MCF-7, which showed that the radiosensitivity of HepG 2 and EC-9706 was higher than that of MCF-7. But there was no statistical difference of SF between HepG 2 and EC-9706. SCGE: The difference of radiosensitivity among these three tumor cell lines was significant after 8 Gy γ-ray irradiation. Conclusion: The multi-utilization of many biological parameter is hopeful to evaluate the radiosensitivity of tumor cells more objectively and exactly. (authors)

  14. Cell-based lipid flippase assay employing fluorescent lipid derivatives

    DEFF Research Database (Denmark)

    Jensen, Maria Stumph; Costa, Sara; Günther-Pomorski, Thomas

    2016-01-01

    , studies of individual P4-ATPase family members from fungi, plants, and animals show that P4-ATPases differ in their substrate specificities and mediate transport of a broader range of lipid substrates. Here, we describe an assay based on fluorescent lipid derivatives to monitor and characterize lipid...

  15. Quality Assurance in the Polio Laboratory. Cell Sensitivity and Cell Authentication Assays.

    Science.gov (United States)

    Dunn, Glynis

    2016-01-01

    The accuracy of poliovirus surveillance is largely dependent on the quality of the cell lines used for virus isolation, which is the foundation of poliovirus diagnostic work. Many cell lines are available for the isolation of enteroviruses, whilst genetically modified L20B cells can be used as a diagnostic tool for the identification of polioviruses. To be confident that cells can consistently isolate the virus of interest, it is necessary to have a quality assurance system in place, which will ensure that the cells in use are not contaminated with other cell lines or microorganisms and that they remain sensitive to the viruses being studied.The sensitivity of cell lines can be assessed by the regular testing of a virus standard of known titer in the cell lines used for virus isolation. The titers obtained are compared to previously obtained titers in the same assay, so that any loss of sensitivity can be detected.However, the detection of cell line cross contamination is more difficult. DNA bar coding is a technique that uses a short DNA sequence from a standardized position in the genome as a molecular diagnostic assay for species-level identification. For almost all groups of higher animals, the cytochrome c oxidase subunit 1 of mitochondrial DNA (CO1) is emerging as the standard barcode region. This region is 648 nucleotide base pairs long in most phylogenetic groups and is flanked by regions of conserved sequences, making it relatively easy to isolate and analyze. DNA barcodes vary among individuals of the same species to a very minor degree (generally less than 1-2 %), and a growing number of studies have shown that the COI sequences of even closely related species differ by several per cent, making it possible to identify different species with high confidence.

  16. Alternative Methods for the Detection of Emerging Marine Toxins: Biosensors, Biochemical Assays and Cell-Based Assays

    Directory of Open Access Journals (Sweden)

    Laia Reverté

    2014-11-01

    Full Text Available The emergence of marine toxins in water and seafood may have a considerable impact on public health. Although the tendency in Europe is to consolidate, when possible, official reference methods based on instrumental analysis, the development of alternative or complementary methods providing functional or toxicological information may provide advantages in terms of risk identification, but also low cost, simplicity, ease of use and high-throughput analysis. This article gives an overview of the immunoassays, cell-based assays, receptor-binding assays and biosensors that have been developed for the screening and quantification of emerging marine toxins: palytoxins, ciguatoxins, cyclic imines and tetrodotoxins. Their advantages and limitations are discussed, as well as their possible integration in research and monitoring programs.

  17. Alternative Methods for the Detection of Emerging Marine Toxins: Biosensors, Biochemical Assays and Cell-Based Assays

    Science.gov (United States)

    Reverté, Laia; Soliño, Lucía; Carnicer, Olga; Diogène, Jorge; Campàs, Mònica

    2014-01-01

    The emergence of marine toxins in water and seafood may have a considerable impact on public health. Although the tendency in Europe is to consolidate, when possible, official reference methods based on instrumental analysis, the development of alternative or complementary methods providing functional or toxicological information may provide advantages in terms of risk identification, but also low cost, simplicity, ease of use and high-throughput analysis. This article gives an overview of the immunoassays, cell-based assays, receptor-binding assays and biosensors that have been developed for the screening and quantification of emerging marine toxins: palytoxins, ciguatoxins, cyclic imines and tetrodotoxins. Their advantages and limitations are discussed, as well as their possible integration in research and monitoring programs. PMID:25431968

  18. Simultaneous determination of gene expression and bacterial identity in single cells in defined mixtures of pure cultures

    DEFF Research Database (Denmark)

    Poulsen, Lars K.; Dalton, Helen M.; Angels, Mark

    1997-01-01

    A protocol was developed to achieve the simultaneous determination of gene expression and bacterial identity at the level of single cells: a chromogenic beta-galactosidase activity assay was combined with in situ hybridization of Fluorescently labelled oligonucleotide probes to rRNA. The method...... allows monitoring of gene expression and quantification of beta-galactosidase activity in single cells....

  19. Geometry-induced injection dispersion in single-cell protein electrophoresis.

    Science.gov (United States)

    Pan, Qiong; Herr, Amy E

    2018-02-13

    Arrays of microwells are widely used to isolate individual cells, facilitate high throughput cytometry assays, and ensure compatibility of those assays with whole-cell imaging. Microwell geometries have recently been utilized for handling and preparation of single-cell lysate, prior to single-cell protein electrophoresis. It is in the context of single-cell electrophoresis that we investigate the interplay of microwell geometry (circular, rectangular, triangular) and transport (diffusion, electromigration) on the subsequent performance of single-cell polyacrylamide gel electrophoresis (PAGE) for protein targets. We define and measure injector-induced dispersion during PAGE, and develop a numerical model of band broadening sources, experimentally validate the numerical model, and then identify operating conditions (characterized through the Peclet number, Pe) that lead to microwell-geometry induced losses in separation performance. With analysis of mammalian cells as a case study, we sought to understand at what Pe is the PAGE separation performance adversely sensitized to the microwell geometry. In developing design rules, we find that for the microwell geometries that are the most suitable for isolation of mammalian cells and moderate mass protein targets, the Pe is usually small enough (Pe geometry on protein PAGE of single-cell lysate. In extreme cases where the largest mammalian cells are analyzed (Pe > ∼20), consideration of Pe suggests using a rectangular - and not the widely used circular - microwell geometry to maximize protein PAGE separation performance. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2018-04-30

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

  1. Mapping cellular hierarchy by single-cell analysis of the cell surface repertoire.

    Science.gov (United States)

    Guo, Guoji; Luc, Sidinh; Marco, Eugenio; Lin, Ta-Wei; Peng, Cong; Kerenyi, Marc A; Beyaz, Semir; Kim, Woojin; Xu, Jian; Das, Partha Pratim; Neff, Tobias; Zou, Keyong; Yuan, Guo-Cheng; Orkin, Stuart H

    2013-10-03

    Stem cell differentiation pathways are most often studied at the population level, whereas critical decisions are executed at the level of single cells. We have established a highly multiplexed, quantitative PCR assay to profile in an unbiased manner a panel of all commonly used cell surface markers (280 genes) from individual cells. With this method, we analyzed over 1,500 single cells throughout the mouse hematopoietic system and illustrate its utility for revealing important biological insights. The comprehensive single cell data set permits mapping of the mouse hematopoietic stem cell differentiation hierarchy by computational lineage progression analysis. Further profiling of 180 intracellular regulators enabled construction of a genetic network to assign the earliest differentiation event during hematopoietic lineage specification. Analysis of acute myeloid leukemia elicited by MLL-AF9 uncovered a distinct cellular hierarchy containing two independent self-renewing lineages with different clonal activities. The strategy has broad applicability in other cellular systems. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Quality Control Assays for Clinical-Grade Human Mesenchymal Stromal Cells: Validation Strategy.

    Science.gov (United States)

    Radrizzani, Marina; Soncin, Sabrina; Bolis, Sara; Lo Cicero, Viviana; Andriolo, Gabriella; Turchetto, Lucia

    2016-01-01

    The present chapter focuses on the validation of the following analytical methods for the control of mesenchymal stromal cells (MSC) for cell therapy clinical trials: Microbiological control for cellular product Endotoxin assay Mycoplasma assay Cell count and viability Immunophenotype Clonogenic potential (CFU-F assay) In our lab, these methods are in use for product release, process control or control of the biological starting materials. They are described in detail in the accompanying Chapter 19.For each method, validation goals and strategy are presented, and a detailed experimental scheme is proposed.

  3. IL-2 absorption affects IFN-gamma and IL-5, but not IL-4 producing memory T cells in double color cytokine ELISPOT assays.

    Science.gov (United States)

    Quast, Stefan; Zhang, Wenji; Shive, Carey; Kovalovski, Damian; Ott, Patrick A; Herzog, Bernhard A; Boehm, Bernhard O; Tary-Lehmann, Magdalena; Karulin, Alexey Y; Lehmann, Paul V

    2005-09-01

    Cytokine assays are gaining increasing importance for human immune monitoring because they reliably detect antigen-specific T cells in primary PBMC, even at low clonal sizes. Double color ELISPOT assays permit the simultaneous visualization of cells producing two different cytokines. Permitting the simultaneous assessment of type 1 and 2 immunity and due to the limited numbers of PBMC available from human study subjects, double color assays should be particularly attractive for clinical trials. Since the performance of double color assays has not yet been validated, we set out to compare them to single color measurements. Testing the recall antigen-induced cytokine response of PBMC, we found that double color assays regularly provided lower numbers of IFN-gamma and IL-5 spots than single color measurements when IL-2 detection was part of the double color assay. We showed that the inhibitory effect resulted from IL-2 absorption and could be overcome by either antibody free preactivation cultures or by inclusion of anti-CD28 antibody. In contrast, the simultaneous detection of IL-2 did not affect the numbers of IL-4 spots. Therefore, unlike IL-2/IL-4 and IFN-gamma/IL-5 assays, IL-2/IFN-gamma, and IL-2/IL-5 assays require compensation for the IL-2 capture to provide accurate numbers for the frequencies of cytokine producing memory T cells.

  4. Distinct gene expression signatures in human embryonic stem cells differentiated towards definitive endoderm at single-cell level

    DEFF Research Database (Denmark)

    Norrman, Karin; Strömbeck, Anna; Semb, Henrik

    2013-01-01

    Characterization of directed differentiation of pluripotent stem cells towards therapeutically relevant cell types, including pancreatic beta-cells and hepatocytes, depends on molecular markers and assays that resolve the signature of individual cells. Pancreas and liver both have a common origin...... for the three activin A based protocols applied. Our data provide novel insights in DE gene expression at the cellular level of in vitro differentiated human embryonic stem cells, and illustrate the power of using single-cell gene expression profiling to study differentiation heterogeneity and to characterize...

  5. Toxcast Profiling in a Human Stem Cell Assay for Developmental Toxicity (SOT)

    Science.gov (United States)

    We correlated the ToxCast library in a metabolic biomarker-based in vitro assay (Stemina devTOXqP) utilizing human embryonic stem (hES) cells (H9 line). This assay identifies the concentration of a chemical that disrupts cellular metabolism in a manner indicative of teratogenic...

  6. Functional cell mediated lympholysis I. Description of the assay

    International Nuclear Information System (INIS)

    Goeken, N.E.; Thompson, J.S.

    1981-01-01

    The anamnestic response by human bi-directional (BD) mixed lymphocyte cultures (MLC) to restimulation by cells of the original stimulating type is generally strikingly reduced as compared to that of standard one-way cultures. This difference was shown not to be related to a change in kinetics nor was it due to exhaustion of the media or soluble factors since fresh media did not ameliorate the effect nor were supernatants from BD cultures found to be suppressive. The relative inhibition was also not reversed by removal of the allogeneic cells by phenotype specific antiserum. Cytotoxic tests with donor and responder specific antisera revealed that the cells bearing that phenotype were dramatically reduced in BD as compared to one-way cultures. Thus, the diminished secondary response appears to be due to cytotoxic elimination of the responder cells. This allogeneic cytotoxicity is dependent on non-T, phagocytic, adherent cells. The phenomenon is called Functional Cell Mediated Lympholysis (F-CML). (author)

  7. Detection of circulating immune complexes by Raji cell assay: comparison of flow cytometric and radiometric methods

    International Nuclear Information System (INIS)

    Kingsmore, S.F.; Crockard, A.D.; Fay, A.C.; McNeill, T.A.; Roberts, S.D.; Thompson, J.M.

    1988-01-01

    Several flow cytometric methods for the measurement of circulating immune complexes (CIC) have recently become available. We report a Raji cell flow cytometric assay (FCMA) that uses aggregated human globulin (AHG) as primary calibrator. Technical advantages of the Raji cell flow cytometric assay are discussed, and its clinical usefulness is evaluated in a method comparison study with the widely used Raji cell immunoradiometric assay. FCMA is more precise and has greater analytic sensitivity for AHG. Diagnostic sensitivity by the flow cytometric method is superior in systemic lupus erythematosus (SLE), rheumatoid arthritis, and vasculitis patients: however, diagnostic specificity is similar for both assays, but the reference interval of FCMA is narrower. Significant correlations were found between CIC levels obtained with both methods in SLE, rheumatoid arthritis, and vasculitis patients and in longitudinal studies of two patients with cerebral SLE. The Raji cell FCMA is recommended for measurement of CIC levels to clinical laboratories with access to a flow cytometer

  8. Detection of circulating immune complexes by Raji cell assay: comparison of flow cytometric and radiometric methods

    Energy Technology Data Exchange (ETDEWEB)

    Kingsmore, S.F.; Crockard, A.D.; Fay, A.C.; McNeill, T.A.; Roberts, S.D.; Thompson, J.M.

    1988-01-01

    Several flow cytometric methods for the measurement of circulating immune complexes (CIC) have recently become available. We report a Raji cell flow cytometric assay (FCMA) that uses aggregated human globulin (AHG) as primary calibrator. Technical advantages of the Raji cell flow cytometric assay are discussed, and its clinical usefulness is evaluated in a method comparison study with the widely used Raji cell immunoradiometric assay. FCMA is more precise and has greater analytic sensitivity for AHG. Diagnostic sensitivity by the flow cytometric method is superior in systemic lupus erythematosus (SLE), rheumatoid arthritis, and vasculitis patients: however, diagnostic specificity is similar for both assays, but the reference interval of FCMA is narrower. Significant correlations were found between CIC levels obtained with both methods in SLE, rheumatoid arthritis, and vasculitis patients and in longitudinal studies of two patients with cerebral SLE. The Raji cell FCMA is recommended for measurement of CIC levels to clinical laboratories with access to a flow cytometer.

  9. Whole cell based electrical impedance sensing approach for a rapid nanotoxicity assay

    Energy Technology Data Exchange (ETDEWEB)

    Hondroulis, Evangelia; Liu Chang; Li Chenzhong, E-mail: licz@fiu.edu [Nanobioengineering/Bioelectronics Laboratory, Department of Biomedical Engineering, Florida International University, 10555 West Flagler Street, Miami, FL 33174 (United States)

    2010-08-06

    A whole cell based biosensor for rapid real-time testing of human and environmental toxicity of nanoscale materials is reported. Recent studies measuring nanoparticle cytotoxicity in vitro provide a final measurement of toxicity to a cell culture overlooking the ongoing cytotoxic effects of the nanoparticles over the desired timeframe. An array biosensor capable of performing multiple cytotoxicity assays simultaneously was designed to address the need for a consistent method to measure real-time assessments of toxicity. The impedimetric response of human lung fibroblasts (CCL-153) and rainbow trout gill epithelial cells (RTgill-W1) when exposed to gold and silver nanoparticles (AuNPs, AgNPs), single walled carbon nanotubes (SWCNTs) and cadmium oxide (CdO) was tested. Exposure to CdO particles exhibited the fastest rate of cytotoxicity and demonstrated the biosensor's ability to monitor toxicity instantaneously in real time. Advantages of the present method include shorter run times, easier usage, and multi-sample analysis leading to a method that can monitor the kinetic effects of nanoparticle toxicity continuously over a desired timeframe.

  10. Whole cell based electrical impedance sensing approach for a rapid nanotoxicity assay

    Science.gov (United States)

    Hondroulis, Evangelia; Liu, Chang; Li, Chen-Zhong

    2010-08-01

    A whole cell based biosensor for rapid real-time testing of human and environmental toxicity of nanoscale materials is reported. Recent studies measuring nanoparticle cytotoxicity in vitro provide a final measurement of toxicity to a cell culture overlooking the ongoing cytotoxic effects of the nanoparticles over the desired timeframe. An array biosensor capable of performing multiple cytotoxicity assays simultaneously was designed to address the need for a consistent method to measure real-time assessments of toxicity. The impedimetric response of human lung fibroblasts (CCL-153) and rainbow trout gill epithelial cells (RTgill-W1) when exposed to gold and silver nanoparticles (AuNPs, AgNPs), single walled carbon nanotubes (SWCNTs) and cadmium oxide (CdO) was tested. Exposure to CdO particles exhibited the fastest rate of cytotoxicity and demonstrated the biosensor's ability to monitor toxicity instantaneously in real time. Advantages of the present method include shorter run times, easier usage, and multi-sample analysis leading to a method that can monitor the kinetic effects of nanoparticle toxicity continuously over a desired timeframe.

  11. Whole cell based electrical impedance sensing approach for a rapid nanotoxicity assay

    International Nuclear Information System (INIS)

    Hondroulis, Evangelia; Liu Chang; Li Chenzhong

    2010-01-01

    A whole cell based biosensor for rapid real-time testing of human and environmental toxicity of nanoscale materials is reported. Recent studies measuring nanoparticle cytotoxicity in vitro provide a final measurement of toxicity to a cell culture overlooking the ongoing cytotoxic effects of the nanoparticles over the desired timeframe. An array biosensor capable of performing multiple cytotoxicity assays simultaneously was designed to address the need for a consistent method to measure real-time assessments of toxicity. The impedimetric response of human lung fibroblasts (CCL-153) and rainbow trout gill epithelial cells (RTgill-W1) when exposed to gold and silver nanoparticles (AuNPs, AgNPs), single walled carbon nanotubes (SWCNTs) and cadmium oxide (CdO) was tested. Exposure to CdO particles exhibited the fastest rate of cytotoxicity and demonstrated the biosensor's ability to monitor toxicity instantaneously in real time. Advantages of the present method include shorter run times, easier usage, and multi-sample analysis leading to a method that can monitor the kinetic effects of nanoparticle toxicity continuously over a desired timeframe.

  12. Single-molecule supercoil-relaxation assay as a screening tool to determine the mechanism and efficacy of human topoisomerase IB inhibitors

    Science.gov (United States)

    Seol, Yeonee; Zhang, Hongliang; Agama, Keli; Lorence, Nicholas; Pommier, Yves; Neuman, Keir C.

    2015-01-01

    Human nuclear type IB topoisomerase (Top1) inhibitors are widely used and powerful anti-cancer agents. In this study, we introduce and validate a single-molecule supercoil relaxation assay as a molecular pharmacology tool for characterizing therapeutically relevant Top1 inhibitors. Using this assay, we determined the effects on Top1 supercoil relaxation activity of four Top1 inhibitors; three clinically relevant: camptothecin, LMP-400, LMP-776 (both indenoisoquinoline derivatives), and one natural product in preclinical development, lamellarin-D. Our results demonstrate that Top1 inhibitors have two distinct effects on Top1 activity: a decrease in supercoil relaxation rate and an increase in religation inhibition. The type and magnitude of the inhibition mode depend both on the specific inhibitor and on the topology of the DNA substrate. In general, the efficacy of inhibition is significantly higher with supercoiled than with relaxed DNA substrates. Comparing single-molecule inhibition with cell growth inhibition (IC50) measurements showed a correlation between the binding time of the Top1 inhibitors and their cytotoxic efficacy, independent of the mode of inhibition. This study demonstrates that the single-molecule supercoil relaxation assay is a sensitive method to elucidate the detailed mechanisms of Top1 inhibitors and is relevant for the cellular efficacy of Top1 inhibitors. PMID:26351326

  13. A NOVel ELISPOT assay to quantify HLA-specific B cells in HLA-immunized individuals

    NARCIS (Netherlands)

    Heidt, S.; Roelen, D.L.; de Vaal, Y.J.; Kester, M.G.; Eijsink, C.; Thomas, S.; van Besouw, N.M.; Volk, H.D.; Weimar, W.; Claas, F.H.; Mulder, A.

    2012-01-01

    Quantification of the humoral alloimmune response is generally achieved by measuring serum HLA antibodies, which provides no information about the cells involved in the humoral immune response. Therefore, we have developed an HLA-specific B-cell ELISPOT assay allowing for quantification of B cells

  14. Demonstration of a visual cell-based assay for screening glucose ...

    Indian Academy of Sciences (India)

    Keywords. CHO cells; eGFP; GLUT4; live cell imaging; natural product; qualitative assay; translocation. Abstract. Insulin-stimulated translocation of glucose transporter 4 (GLUT4) to cell membrane leading to glucose uptake is the rate-limiting step in diabetes. It is also a defined target of antidiabetic drug research. Existing ...

  15. Anucleate Cell Blue Assay: a Useful Tool for Identifying Novel Type II Topoisomerase Inhibitors

    OpenAIRE

    Oyamada, Yoshihiro; Ito, Hideaki; Fujimoto-Nakamura, Mika; Tanitame, Akihiko; Iwai, Noritaka; Nagai, Kazuo; Yamagishi, Jun-ichi; Wachi, Masaaki

    2006-01-01

    About 95,000 compounds were screened by the anucleate cell blue assay. Fifty-one of the hit compounds had various structures and showed inhibitory activity against DNA gyrase and/or topoisomerase IV. Moreover, the compounds exhibited antibacterial activity against a fluoroquinolone- and novobiocin-resistant strain of Staphylococcus aureus. The anucleate cell blue assay is therefore a useful tool for finding novel type II topoisomerase inhibitors.

  16. Determination of immune complexes in sera from dogs with various diseases by mastocytoma cell assay.

    OpenAIRE

    Targowski, S

    1982-01-01

    Canine immunoglobulin G complexed with particulate or soluble antigen can bind to the Fc receptors on the mastocytoma cells. Attachment of immune complexes composed of immunoglobulin G and soluble antigen (ovalbumin) to mastocytoma cells was detected by an inhibition of rosette formation with indicator cells (sensitized sheep erythrocytes). Therefore, canine circulating immune complexes may also attach to mastocytoma cells and inhibit rosette formation (mastocytoma cell assay). Sera from 326 ...

  17. Effect of CD4+ T cell count and antiretroviral treatment on two serological HIV incidence assays.

    Science.gov (United States)

    Hladik, Wolfgang; Olara, Dennis; Mermin, Jonathan; Moore, David; Were, Willy; Alexander, Lorraine; Downing, Robert

    2012-01-01

    Serological assays are increasingly being used to measure HIV incidence in cross-sectional studies, but their specificity to determine incident infections remains problematic. We estimated the specificity of the BED assay in a cohort of long-term HIV-infected adults before and during antiretroviral treatment (ART) and evaluated an HIV avidity assay to detect BED-based false-recent results. We used the BED assay to test stored specimens from known long-term HIV-1-infected adult Ugandans before and at 3, 12, and 24 months after ART initiation. We evaluated the frequency of false-recent classifications by ART status and CD4(+) T(+) cell count. Specimens classified as BED false-recent were further tested with an avidity assay. In all, 950 blood specimens from 253 adults were tested with the BED assay. Of these, 149 (15.7%) specimens tested false-recent and 64 (24.9%) individuals tested false-recent at least once. Among all specimens tested, the proportion of false-recent rose with increasing CD4(+) cell count (<250 cells/μl: 11.3%, 250-499: 17.8%, ≥500: 21.4%; p for trend=0.002). Of 197 persons with all four BED results available, 75.6% were classified as long-term infected throughout and 8.1% as false-recent throughout; the remainder changed classification once (12.2%) or twice (4.1%). Of 105 false-recent specimens retested with the avidity assay, 101 (96.2%) were correctly classified as "long-term." The BED assay's specificity varied with CD4(+) cell count and use of ART. Knowledge of these parameters for blood samples could improve incidence estimates using the BED assay. The additional use of an avidity assay may help to minimize the proportion of BED false-recent specimens.

  18. Renal response assayed by survival of tubule epithelial cells

    International Nuclear Information System (INIS)

    Withers, H.R.; Mason, K.A.

    1985-01-01

    The epithelium of the renal tubules is essentially non-proliferative and hence is slow to be depleted after irradiation. Ultimately, however, depletion occurs. If cells survive within a tubule they regenerate the epithelial lining. After higher doses, e.g. greater than 12 Gy, some tubules are completely depopulated of epithelium giving rise to a histological picture of empty tubules interspersed with regenerated tubules. It is assumed that nephrons are all essentially the same size, that cell survival is a random probability and that, therefore, when a proportion of tubules are completely devoid of epithelium, those that aren't have regenerated from one or a few cells, the distribution of numbers of survivors per tubule following Poisson statistics. Based on these assumptions it is possible to determine a dose-survival relationship for renal tubule cells

  19. Gravisensing in single-celled systems

    Science.gov (United States)

    Braun, M.; Limbach, C.

    Single-celled systems are favourable cell types for studying several aspects of gravisensing and gravitropic responses. Whether and how actin is involved in both processes in higher plant statocytes is still a matter of intensive debate. In single-celled and tip-growing characean rhizoids and protonemata, however, there is clear evidence that actin is a central keyplayer controlling polarized growth and the mechanisms of gravity sensing and growth reorientation. Both cell types exhibit a unique actin polymerization in the extending tip, strictly colocalized with the prominent ER-aggregate in the center of the Spitzenkoerper. The local accumulation of ADF and profilin in this central array suggest that actin polymerization is controlled by these actin-binding proteins, which can be regulated by calcium, pH and a variety of other parameters. Distinct actin filaments extend even into the outermost tip and form a dense meshwork in the apical and subapical region, before they become bundled by villin to form two populations of thick actin cables that generate rotational cytoplasmic streaming in the basal region. Actomyosin not only mediates the delivery of secretory vesicles to the growing tip and controls the incorporation pattern of cell wall material, but also coordinates the tip-focused distribution pattern of calcium channels in the apical membrane. They establish the tip-high calcium gradient, a prerequisite for exocytosis. Microgravity experiments have added much to our understanding that both cell types use an efficient actomyosin-based system to control and correct the position of their statoliths and to direct sedimenting statoliths to confined graviperception sites at the plasma membrane. Actin's involvement in the graviresponses is more indirect. The upward growth of negatively gravitropic protonemata was shown to be preceded by a statolith-induced relocalization the Ca2+-calcium gradient to the upper flank that does not occur in positively gravitropic

  20. High-content imaging assays on a miniaturized 3D cell culture platform.

    Science.gov (United States)

    Joshi, Pranav; Datar, Akshata; Yu, Kyeong-Nam; Kang, Soo-Yeon; Lee, Moo-Yeal

    2018-03-06

    The majority of high-content imaging (HCI) assays have been performed on two-dimensional (2D) cell monolayers for its convenience and throughput. However, 2D-cultured cell models often do not represent the in vivo characteristics accurately and therefore reduce the predictability of drug toxicity/efficacy in vivo. Recently, three-dimensional (3D) cell-based HCI assays have been demonstrated to improve predictability, but its use is limited due to difficulty in maneuverability and low throughput in cell imaging. To alleviate these issues, we have developed miniaturized 3D cell culture on a micropillar/microwell chip and demonstrated high-throughput HCI assays for mechanistic toxicity. Briefly, Hep3B human hepatoma cell line was encapsulated in a mixture of alginate and fibrin gel on the micropillar chip, cultured in 3D, and exposed to six model compounds in the microwell chip for rapidly assessing mechanistic hepatotoxicity. Several toxicity parameters, including DNA damage, mitochondrial impairment, intracellular glutathione level, and cell membrane integrity were measured on the chip, and the IC 50 values of the compounds at different readouts were determined to investigate the mechanism of toxicity. Overall, the Z' factors were between 0.6 and 0.8 for the HCI assays, and the coefficient of variation (CV) were below 20%. These results indicate high robustness and reproducibility of the HCI assays established on the miniaturized 3D cell culture chip. In addition, it was possible to determine the predominant mechanism of toxicity using the 3D HCI assays. Therefore, our miniaturized 3D cell culture coupled with HCI assays has great potential for high-throughput screening (HTS) of compounds and mechanistic toxicity profiling. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. A new single nucleotide polymorphisms typing method and device by bioluminometric assay coupled with a photodiode array

    Science.gov (United States)

    Kamahori, Masao; Harada, Kunio; Kambara, Hideki

    2002-11-01

    Easy and inexpensive single nucleotide polymorphisms (SNPs) typing systems are required for the practice of genetic testing as well as genetic medicine. Most of the SNPs typing systems use laser-induced fluorescence detection coupled with fluorophore tagging on DNA, which are expensive. A new simple and inexpensive SNPs typing system is presented. It uses a bioluminometric assay coupled with modified primer extension reactions and an inexpensive photodiode array for the luminometric detection. The reagents consumed in the assay are also inexpensive. Although the system is very small, simple and inexpensive, it gives enough sensitivity for detecting target DNAs as small as 10 fmol, which is good enough for SNPs typing.

  2. Single-Step Multiplex PCR Assay for Characterization of New World Leishmania Complexes

    Science.gov (United States)

    Harris, Eva; Kropp, Gerald; Belli, Alejandro; Rodriguez, Betzabé; Agabian, Nina

    1998-01-01

    We have developed a PCR assay for one-step differentiation of the three complexes of New World Leishmania (Leishmania braziliensis, Leishmania mexicana, and Leishmania donovani). This multiplex assay is targeted to the spliced leader RNA (mini-exon) gene repeats of these organisms and can detect all three complexes simultaneously, generating differently sized products for each complex. The assay is specific to the Leishmania genus and does not recognize related kinetoplastid protozoa, such as Trypanosoma cruzi, Trypanosoma brucei, and Crithidia fasciculata. It correctly identified Leishmania species with a broad geographic distribution in Central and South America. The sensitivity of the PCR amplification ranged from 1 fg to 10 pg of DNA (0.01 to 100 parasites), depending on the complex detected. Crude extracts of cultured parasites, prepared simply by boiling diluted cultures, served as excellent templates for amplification. Crude preparations of clinical material were also tested. The assay detected L. braziliensis in dermal scrapings from cutaneous leishmanial lesions, Leishmania chagasi in dermal scrapings of atypical cutaneous leishmaniasis, and L. mexicana from lesion aspirates from infected hamsters. We have minimized the material requirements and maximized the simplicity, rapidity, and informative content of this assay to render it suitable for use in laboratories in countries where leishmaniasis is endemic. This assay should be useful for rapid in-country identification of Leishmania parasites, particularly where different Leishmania complexes are found in the same geographical area. PMID:9650950

  3. Quantum Dot Nanotoxicity Investigations Using Human Lung Cells and TOXOR Electrochemical Enzyme Assay Methodology.

    Science.gov (United States)

    O'Hara, Tony; Seddon, Brian; O'Connor, Andrew; McClean, Siobhán; Singh, Baljit; Iwuoha, Emmanuel; Fuku, Xolile; Dempsey, Eithne

    2017-01-27

    Recent studies have suggested that certain nanomaterials can interfere with optically based cytotoxicity assays resulting in underestimations of nanomaterial toxicity. As a result there has been growing interest in the use of whole cell electrochemical biosensors for nanotoxicity applications. Herein we report application of an electrochemical cytotoxicity assay developed in house (TOXOR) in the evaluation of toxic effects of mercaptosuccinic acid capped cadmium telluride quantum dots (MSA capped CdTe QDs), toward mammalian cells. MSA capped CdTe QDs were synthesized, characterized, and their cytotoxicity toward A549 human lung epithelial cells investigated. The internalization of QDs within cells was scrutinized via confocal microscopy. The cytotoxicity assay is based on the measurement of changes in cellular enzyme acid phosphatase upon 24 h exposure to QDs. Acid phosphatase catalyzes dephosphorylation of 2-naphthyl phosphate to 2-naphthol (determined by chronocoulometry) and is indicative of metabolic activity in cells. The 24 h IC50 (concentration resulting in 50% reduction in acid phosphatase activity) value for MSA capped CdTe QDs was found to be 118 ± 49 μg/mL using the TOXOR assay and was in agreement with the MTT assay (157 ± 31 μg/mL). Potential uses of this electrochemical assay include the screening of nanomaterials, environmental toxins, in addition to applications in the pharmaceutical, food, and health sectors.

  4. Single-cell analysis of the fate of c-kit-positive bone marrow cells

    Science.gov (United States)

    Czarna, Anna; Sanada, Fumihiro; Matsuda, Alex; Kim, Junghyun; Signore, Sergio; Pereira, João D.; Sorrentino, Andrea; Kannappan, Ramaswamy; Cannatà, Antonio; Hosoda, Toru; Rota, Marcello; Crea, Filippo; Anversa, Piero; Leri, Annarosa

    2017-10-01

    The plasticity of c-kit-positive bone marrow cells (c-kit-BMCs) in tissues different from their organ of origin remains unclear. We tested the hypothesis that c-kit-BMCs are functionally heterogeneous and only a subgroup of these cells possesses cardiomyogenic potential. Population-based assays fall short of identifying the properties of individual stem cells, imposing on us the introduction of single cell-based approaches to track the fate of c-kit-BMCs in the injured heart; they included viral gene-tagging, multicolor clonal-marking and transcriptional profiling. Based on these strategies, we report that single mouse c-kit-BMCs expand clonally within the infarcted myocardium and differentiate into specialized cardiac cells. Newly-formed cardiomyocytes, endothelial cells, fibroblasts and c-kit-BMCs showed in their genome common sites of viral integration, providing strong evidence in favor of the plasticity of a subset of BMCs expressing the c-kit receptor. Similarly, individual c-kit-BMCs, which were infected with multicolor reporters and injected in infarcted hearts, formed cardiomyocytes and vascular cells organized in clusters of similarly colored cells. The uniform distribution of fluorescent proteins in groups of specialized cells documented the polyclonal nature of myocardial regeneration. The transcriptional profile of myogenic c-kit-BMCs and whole c-kit-BMCs was defined by RNA sequencing. Genes relevant for engraftment, survival, migration, and differentiation were enriched in myogenic c-kit-BMCs, a cell subtype which could not be assigned to a specific hematopoietic lineage. Collectively, our findings demonstrate that the bone marrow comprises a category of cardiomyogenic, vasculogenic and/or fibrogenic c-kit-positive cells and a category of c-kit-positive cells that retains an undifferentiated state within the damaged heart.

  5. Analysis of Chemopredictive Assay for Targeting Cancer Stem Cells in Glioblastoma Patients

    Directory of Open Access Journals (Sweden)

    Candace M. Howard

    2017-04-01

    were estimated for CSC, bulk tumor, and combined assay responses for the standard-of-care TMZ treatment; sensitivities/specificities, areas under the curve (AUCs, and risk reclassification components were examined. Results: Median follow-up was 8 months (range 3-49 months. For every 5% increase in in vitro CSC cell kill by TMZ, 12-month patient response (nonrecurrence of cancer increased two-fold, OR = 2.2 (P = .016. Similar but somewhat less supported associations with the bulk tumor test were seen, OR = 2.75 (P = .07 for each 5% bulk tumor cell kill by TMZ. Combining CSC and bulk tumor assay results in a single model yielded a statistically supported CSC association, OR = 2.36 (P = .036, but a much attenuated remaining bulk tumor association, OR = 1.46 (P = .472. AUCs and [sensitivity/specificity] at optimal outpoints (>40% CSC cell kill and >55% bulk tumor cell kill were AUC = 0.989 [sensitivity = 100/specificity = 97], 0.972 [100/89], and 0.989 [100/97] for the CSC only, bulk tumor only, and combined models, respectively. Risk categorization of patients was improved by 11% when using the CSC test in conjunction with the bulk test (risk reclassification nonevent net reclassification improvement [NRI] and overall NRI = 0.111, P = .030. Median recurrence time was 20 months for patients with a positive (>40% cell kill CSC test versus only 3 months for those with a negative CSC test, whereas median recurrence time was 13 months versus 4 months for patients with a positive (>55% cell kill bulk test versus negative. Similar favorable results for the CSC test were observed for PFS and OS outcomes. Panel results across 14 potential other treatments indicated that 34/41 (83% potentially more optimal alternative therapies may have been chosen using CSC results, whereas 27/41 (66% alternative therapies may have been chosen using bulk tumor results. Conclusions: The ChemoID CSC drug response assay has the potential to increase the accuracy of bulk

  6. Osteoconductivity of Complex Biomaterials Assayed by Fluorescent-Engineered Osteoblast-like Cells.

    Science.gov (United States)

    Manfrini, Marco; Mazzoni, Elisa; Barbanti-Brodano, Giovanni; Nocini, Pierfrancesco; D'agostino, Antonio; Trombelli, Leonardo; Tognon, Mauro

    2015-04-01

    Biomaterials employed for the bone regeneration can be assayed for specific features such as osteoconductivity and gene expression. In this study, the composite HA/collagen/chondroitin-sulfate biomaterial was investigated using an engineered human cell line, named Saos-eGFP. This cell line, a green fluorescent engineered human osteoblast-like cell, was employed as a cellular model for the in vitro study of biomaterial characteristics. The cytotoxicity was indirectly evaluated by fluorescence detection, osteoconductivity was assayed both by fluorescence and electron microscope analysis as well as cell morphology, whereas the RT-PCR technique was employed to assay gene expression. Saos-eGFP cells viability detection after 24 and 96 h of incubation showed that biomaterial enables the adhesion and proliferation of seeded cells as well as that of the plastic surface, the control. Fluorescence and scanning electron microscopy (SEM) analyses indicated that Saos-eGFP cells were homogeneously distributed on the HA granule surfaces, exhibiting cytoplasmic bridges, and were localized on the collagen-chondroitin sulfate extra-cellular matrix. An expression analysis of specific genes encoding for differentiation markers, showed that biomaterial assayed did not alter the osteogenic pathway of the Saos-eGFP cell line. Our assays confirm the cytocompatibility of this biomaterial, suggesting an osteoconductive capacity mediated by its chemical contents. We showed that the Saos-eGFP cellular model is suitable for in vitro biomaterial assays, and more specifically for assessing osteoconductivity. This result suggests that the cytocompatibility and osteoconductive features of the biomaterial assayed as bone substitute, could have a positive downstream effect on implant osteo-integration.

  7. Ovine carotid artery-derived cells as an optimized supportive cell layer in 2-D capillary network assays.

    Directory of Open Access Journals (Sweden)

    Stefan Weinandy

    Full Text Available BACKGROUND: Endothelial cell co-culture assays are differentiation assays which simulate the formation of capillary-like tubules with the aid of a supportive cell layer. Different cell types have been employed as a supportive cell layer, including human pulmonary artery smooth muscle cells (PASMCs and human mammary fibroblasts. However, these sources of human tissue-derived cells are limited, and more readily accessible human or animal tissue-derived cell sources would simplify the endothelial cell co-culture assay. In the present study, we investigated the potential use of alternative, accessible supportive cells for endothelial cell co-culture assay, including human umbilical cord and ovine carotid artery. METHODS AND RESULTS: Human umbilical artery SMCs (HUASMCs and ovine carotid artery-derived cells were seeded into 96-well plates, followed by addition of human umbilical vein endothelial cells (HUVECs. Nine days after co-culture, cells were fixed, immunostained and analysed using an in vitro angiogenesis quantification tool. Capillary-like structures were detected on ovine carotid artery-derived supportive cell layers. The initial cell number, as well as pro- and anti-angiogenic factors (VEGF, PDGF-BB and Bevacizumab, had a positive or negative influence on the number of capillary-like structures. Furthermore, HUVECs from different donors showed distinct levels of VEGF receptor-2, which correlated with the amount of capillary-like structures. In the case of HUASMC supportive cell layers, HUVECs detached almost completely from the surface. CONCLUSIONS: Cells of different origin have a varying applicability regarding the endothelial cell co-culture assay: under the conditions described here, ovine carotid artery-derived cells seem to be more suitable than HUASMCs for an endothelial co-culture assay. Furthermore, the ovine carotid artery-derived cells are easier to obtain and are in more abundant supply than the currently used dermal or breast

  8. Cell-free antigens of Sporothrix brasiliensis: antigenic diversity and application in an immunoblot assay.

    Science.gov (United States)

    Almeida-Paes, Rodrigo; Bailão, Alexandre Melo; Pizzini, Cláudia Vera; Reis, Rosani Santos; Soares, Célia Maria de Almeida; Peralta, José Mauro; Gutierrez-Galhardo, Maria Clara; Zancopé-Oliveira, Rosely Maria

    2012-11-01

    Sporotrichosis is a subcutaneous mycosis diagnosed by isolation of the fungus in culture. Serological tests for help in diagnosis in general do not use purified or recombinant antigens, because there is a paucity of described immunoreactive proteins, especially for the new described Sporothrix species, such as Sporothrix brasiliensis. This study aims to characterise antigens from S. brasiliensis and verify their application in serodiagnosis of sporotrichosis. An immunoblot assay allied with computer-based analysis was used to identify putative antigenic molecules in a cell-free extracts of both morphological phases of this fungus, and to delineate antigenic polymorphism among seven S. brasiliensis isolates and one S. schenckii Brazilian strain. The mycelial and yeast phase of the fungus originated 14 and 23 reactive bands, respectively, which were variable in intensity. An 85 kDa antigen, verified in the yeast phase of the fungus, was observed in all strains used and the immunodominant protein was identified. This protein, however, cross-react with serum samples from patients infected with other pathogens. The results show that the S. brasiliensis cell-free antigen extract is a single and inexpensive source of antigens, and can be applied on the sporotrichosis serodiagnosis. © 2012 Blackwell Verlag GmbH.

  9. Screening ToxCast™ Phase I Chemicals in a Mouse Embryonic Stem Cell Adherent Cell Differentiation and Cytotoxicity (ACDC) Assay

    Science.gov (United States)

    An Adherent Cell Differentiation and Cytotoxicity (ACDC) in vitro assay with mouse embryonic stem cells was used to screen the ToxCast Phase I chemical library for effects on cellular differentiation and cell number. The U.S. Environmental Protection Agency (EPA) established the ...

  10. Hemocytes of zebra mussels (Dreissena polymorpha are relevant cells for the monitoring of environmental genotoxicity by the comet assay.

    Directory of Open Access Journals (Sweden)

    Marc Bonnard

    2015-06-01

    Full Text Available The measure of DNA integrity by the single cell gel electrophoresis (SCGE or comet assay is especially recommended for its sensitivity and its capacity for detecting different types of damages. Therefore, it has been applied in environmental genotoxicity in a variety of organisms. It appears today necessary to define both reference and threshold levels of DNA damage, for their application in in situ biomonitoring. However, little is known about the influence of both biological (sex, reproduction status or external (temperature… confounding factors on the measure of DNA damage by the comet assay. These variables need to be taken into account if the robustness of the assay is to be established (Jha, 2008. In the zebra mussel Dreissena polymorpha (recommended as a sentinel species in the evaluation of freshwater quality the measure of DNA damage by the comet assay is mainly performed on hemocytes, which are circulating cells involved in key physiological functions such as immunity, homeostasis, detoxication…. This communication will present and discuss results from an innovative study about the variability of the baseline level of DNA damage in hemocytes of mussels encaged for one year in the canal de l’Aisne à la Marne (Reims, according to their sex and their reproductive status. The sensitivity and the suitability of hemocytes in the evaluation of environmental genotoxicity will also be discussed, referring to observations during a 6 month-exposure of mussels in mesocosms to environmentally realistic concentrations of carbamazepine.

  11. Comparison between fibroblast wound healing and cell random migration assays in vitro.

    Science.gov (United States)

    Ascione, Flora; Vasaturo, Angela; Caserta, Sergio; D'Esposito, Vittoria; Formisano, Pietro; Guido, Stefano

    2016-09-10

    Cell migration plays a key role in many biological processes, including cancer growth and invasion, embryogenesis, angiogenesis, inflammatory response, and tissue repair. In this work, we compare two well-established experimental approaches for the investigation of cell motility in vitro: the cell random migration (CRM) and the wound healing (WH) assay. In the former, extensive tracking of individual live cells trajectories by time-lapse microscopy and elaborate data processing are used to calculate two intrinsic motility parameters of the cell population under investigation, i.e. the diffusion coefficient and the persistence time. In the WH assay, a scratch is made in a confluent cell monolayer and the closure time of the exposed area is taken as an easy-to-measure, empirical estimate of cell migration. To compare WH and CRM we applied the two assays to investigate the motility of skin fibroblasts isolated from wild type and transgenic mice (TgPED) overexpressing the protein PED/PEA-15, which is highly expressed in patients with type 2 diabetes. Our main result is that the cell motility parameters derived from CRM can be also estimated from a time-resolved analysis of the WH assay, thus showing that the latter is also amenable to a quantitative analysis for the characterization of cell migration. To our knowledge this is the first quantitative comparison of these two widely used techniques. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Patterning cell using Si-stencil for high-throughput assay

    KAUST Repository

    Wu, Jinbo

    2011-01-01

    In this communication, we report a newly developed cell pattering methodology by a silicon-based stencil, which exhibited advantages such as easy handling, reusability, hydrophilic surface and mature fabrication technologies. Cell arrays obtained by this method were used to investigate cell growth under a temperature gradient, which demonstrated the possibility of studying cell behavior in a high-throughput assay. This journal is © The Royal Society of Chemistry 2011.

  13. Labeling of mesenchymal stem cells for MRI with single-cell sensitivity

    Directory of Open Access Journals (Sweden)

    Ariza de Schellenberger A

    2016-04-01

    Full Text Available Angela Ariza de Schellenberger,1 Harald Kratz,1 Tracy D Farr,2,3 Norbert Löwa,4 Ralf Hauptmann,1 Susanne Wagner,1 Matthias Taupitz,1 Jörg Schnorr,1 Eyk A Schellenberger1 1Department of Radiology, 2Department of Experimental Neurology, Center for Stroke Research Berlin, Charité – Universitätsmedizin Berlin, Berlin, Germany; 3School of Life Sciences, University of Nottingham, Medical School, Nottingham, UK; 4Department of Biomagnetic Signals, Physikalisch-Technische Bundesanstalt Berlin, Berlin, Germany Abstract: Sensitive cell detection by magnetic resonance imaging (MRI is an important tool for the development of cell therapies. However, clinically approved contrast agents that allow single-cell detection are currently not available. Therefore, we compared very small iron oxide nanoparticles (VSOP and new multicore carboxymethyl dextran-coated iron oxide nanoparticles (multicore particles, MCP designed by our department for magnetic particle imaging (MPI with discontinued Resovist® regarding their suitability for detection of single mesenchymal stem cells (MSC by MRI. We achieved an average intracellular nanoparticle (NP load of >10 pg Fe per cell without the use of transfection agents. NP loading did not lead to significantly different results in proliferation, colony formation, and multilineage in vitro differentiation assays in comparison to controls. MRI allowed single-cell detection using VSOP, MCP, and Resovist® in conjunction with high-resolution T2*-weighted imaging at 7 T with postprocessing of phase images in agarose cell phantoms and in vivo after delivery of 2,000 NP-labeled MSC into mouse brains via the left carotid artery. With optimized labeling conditions, a detection rate of ~45% was achieved; however, the experiments were limited by nonhomogeneous NP loading of the MSC population. Attempts should be made to achieve better cell separation for homogeneous NP loading and to thus improve NP

  14. Recommended protocol for the Syrian hamster embryo (SHE) cell transformation assay.

    Science.gov (United States)

    Maire, Marie-Aline; Pant, Kamala; Phrakonkham, Pascal; Poth, Albrecht; Schwind, Karl-Rainer; Rast, Claudine; Bruce, Shannon Wilson; Sly, Jamie E; Bohnenberger, Susanne; Kunkelmann, Thorsten; Schulz, Markus; Vasseur, Paule

    2012-04-11

    The Syrian hamster embryo (SHE) cell transformation assay (CTA) is a short-term in vitro assay recommended as an alternative method for testing the carcinogenic potential of chemicals. SHE cells are "normal" cells since they are diploid, genetically stable, non-tumourigenic, and have metabolic capabilities for the activation of some classes of carcinogens. The CTA, first developed in the 1960s by Berwald and Sachs (1963,1964) [3,4], is based on the change of the phenotypic feature of cell colonies expressing the first steps of the conversion of normal to neoplastic-like cells with oncogenic properties. Pienta et al. (1977) [22] developed a protocol using cryopreserved cells to enhance practicality of the assay and limit sources of variability. Several variants of the assay are currently in use, which mainly differ by the pH at which the assay is performed. We present here the common version of the SHE pH 6.7 CTA and SHE pH 7.0 CTA protocols used in the ECVAM (European Centre for the Validation of Alternative Methods) prevalidation study on CTA reported in this issue. It is recommended that this protocol, in combination with the photo catalogues presented in this issue, should be used in the future and serve as a basis for the development of the OECD test guideline. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Evaluation of a recombinant yeast cell estrogen screening assay.

    OpenAIRE

    Coldham, N G; Dave, M; Sivapathasundaram, S; McDonnell, D P; Connor, C; Sauer, M J

    1997-01-01

    A wide range of chemicals with diverse structures derived from plant and environmental origins are reported to have hormonal activity. The potential for appreciable exposure of humans to such substances prompts the need to develop sensitive screening methods to quantitate and evaluate the risk to the public. Yeast cells transformed with plasmids encoding the human estrogen receptor and an estrogen responsive promoter linked to a reporter gene were evaluated for screening compounds for estroge...

  16. Quantifying rates of cell migration and cell proliferation in co-culture barrier assays reveals how skin and melanoma cells interact during melanoma spreading and invasion.

    Science.gov (United States)

    Haridas, Parvathi; Penington, Catherine J; McGovern, Jacqui A; McElwain, D L Sean; Simpson, Matthew J

    2017-06-21

    Malignant spreading involves the migration of cancer cells amongst other native cell types. For example, in vivo melanoma invasion involves individual melanoma cells migrating through native skin, which is composed of several distinct subpopulations of cells. Here, we aim to quantify how interactions between melanoma and fibroblast cells affect the collective spreading of a heterogeneous population of these cells in vitro. We perform a suite of circular barrier assays that includes: (i) monoculture assays with fibroblast cells; (ii) monoculture assays with SK-MEL-28 melanoma cells; and (iii) a series of co-culture assays initiated with three different ratios of SK-MEL-28 melanoma cells and fibroblast cells. Using immunostaining, detailed cell density histograms are constructed to illustrate how the two subpopulations of cells are spatially arranged within the spreading heterogeneous population. Calibrating the solution of a continuum partial differential equation to the experimental results from the monoculture assays allows us to estimate the cell diffusivity and the cell proliferation rate for the melanoma and the fibroblast cells, separately. Using the parameter estimates from the monoculture assays, we then make a prediction of the spatial spreading in the co-culture assays. Results show that the parameter estimates obtained from the monoculture assays lead to a reasonably accurate prediction of the spatial arrangement of the two subpopulations in the co-culture assays. Overall, the spatial pattern of spreading of the melanoma cells and the fibroblast cells is very similar in monoculture and co-culture conditions. Therefore, we find no clear evidence of any interactions other than cell-to-cell contact and crowding effects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Development of a replication-competent lentivirus assay for dendritic cell-targeting lentiviral vectors

    Directory of Open Access Journals (Sweden)

    Daniel C Farley

    Full Text Available It is a current regulatory requirement to demonstrate absence of detectable replication-competent lentivirus (RCL in lentiviral vector products prior to use in clinical trials. Immune Design previously described an HIV-1-based integration-deficient lentiviral vector for use in cancer immunotherapy (VP02. VP02 is enveloped with E1001, a modified Sindbis virus glycoprotein which targets dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN expressed on dendritic cells in vivo. Vector enveloped with E1001 does not transduce T-cell lines used in standard HIV-1-based RCL assays, making current RCL testing formats unsuitable for testing VP02. We therefore developed a novel assay to test for RCL in clinical lots of VP02. This assay, which utilizes a murine leukemia positive control virus and a 293F cell line expressing the E1001 receptor DC-SIGN, meets a series of evaluation criteria defined in collaboration with US regulatory authorities and demonstrates the ability of the assay format to amplify and detect a hypothetical RCL derived from VP02 vector components. This assay was qualified and used to test six independent GMP production lots of VP02, in which no RCL was detected. We propose that the evaluation criteria used to rationally design this novel method should be considered when developing an RCL assay for any lentiviral vector.

  18. In Vitro Cell Culture Infectivity Assay for Human Noroviruses

    Energy Technology Data Exchange (ETDEWEB)

    Straub, Tim M.; Honer Zu Bentrup, Kerstin A.; Orosz Coghlan, Patricia A.; Dohnalkova, Alice; Mayer, Brooke K.; Bartholomew, Rachel A.; Valdez, Catherine O.; Bruckner-Lea, Cindy J.; Gerba, Charles P.; Abbaszadegan, Morteza; Nickerson, Cheryl A.

    2007-01-30

    Human noroviruses (NoV) cause severe, self-limiting gastroenteritis that typically lasts 24 - 48 hours. The true nature of NoV pathogenesis remains unknown due to the lack of suitable tissue culture or animal models. Here we show, for the first time, that NoV can infect and replicate in an organoid, three-dimensional (3-D) model of human small intestinal epithelium (INT-407). Cellular differentiation for this model was achieved by growing the cells in 3-D on porous collagen I-coated microcarrier beads under conditions of physiological fluid shear in rotating wall vessel bioreactors. Microscopy, PCR, and fluorescent in-situ hybridization were employed to provide evidence of NoV infection. CPE and norovirus RNA was detected at each of the five cell passages for both genogroup I and II viruses. Our results demonstrate that the highly differentiated 3-D cell culture model can support the natural growth of human noroviruses, whereas previous attempts using differentiated monolayer cultures failed.

  19. An Immunofluorescence-Assisted Microfluidic Single Cell Quantitative Reverse Transcription Polymerase Chain Reaction Analysis of Tumour Cells Separated from Blood

    Directory of Open Access Journals (Sweden)

    Kazunori Hoshino

    2015-11-01

    Full Text Available Circulating tumour cells (CTCs are important indicators of metastatic cancer and may provide critical information for individualized treatment. As CTCs are usually very rare, the techniques to obtain information from very small numbers of cells are crucial. Here, we propose a method to perform a single cell quantitative reverse transcription polymerase chain reaction (qPCR analysis of rare tumour cells. We utilized a microfluidic immunomagnetic assay to separate cancer cells from blood. A combination of detailed immunofluorescence and laser microdissection enabled the precise selection of individual cells. Cancer cells that were spiked into blood were successfully separated and picked up for a single cell PCR analysis. The breast cancer cell lines MCF7, SKBR3 and MDAMB231 were tested with 10 different genes. The result of the single cell analysis matched the results from a few thousand cells. Some markers (e.g., ER, HER2 that are commonly used for cancer identification showed relatively large deviations in expression levels. However, others (e.g., GRB7 showed deviations that are small enough to supplement single cell disease profiling.

  20. In vitro red blood cell assay for oxidant toxicity of petroleum oil

    Energy Technology Data Exchange (ETDEWEB)

    Couillard, C.M.; Leighton, F.A. (Univ. of Saskatchewan, Saskatoon (Canada))

    1993-05-01

    Petroleum oil has caused hemolytic anemia in birds and mammals. In birds, an oxidant damage on circulating red cells has been identified as the primary toxic effect of ingested petroleum oils. An in vitro red blood cell assay was developed to discriminate among the oxidant activities of different petroleum oils. The assay used rabbit red blood cells with a rat liver enzyme system and formation of methemoglobin was measured as an indicator of oxidant damage to the red cells. The assay was applied to five different petroleum oils and to naphthalene, a petroleum hydrocarbon known to cause hemolytic anemia. Different petroleum oils differed in their capacity to induce methemoglobin formation. Methemoglobin levels varied from 2.9% with Arabian light crude oil to 6.2% with South Louisiana crude oil. Naphthalene induced formation of up to 37% methemoglobin. Naphthalene and the five petroleum oils generated methemoglobin only in the presence of liver enzymes.

  1. Transport of chlorpromazine in the Caco-2 cell permeability assay: a kinetic study

    NARCIS (Netherlands)

    Broeders, J.J.W.; Eijkeren, J.C.H.; Blaauboer, B.J.; Hermens, J.L.M.

    2012-01-01

    The intestinal transport of compounds can be measured in vitro with Caco-2 cell monolayers. We took a closer look at the exposure and fate of a chemical in the Caco-2 cell assay, including the effect of protein binding. Transport of chlorpromazine (CPZ) was measured in the absorptive and secretory

  2. In vivo assay for the developmental competence of embryo-derived zebrafish cell lines

    NARCIS (Netherlands)

    Speksnijder, JE; Hage, WJ; Lanser, PH; Collodi, P; Zivkovic, D

    We have produced chimeric zebrafish embryos by transplanting permanent embryo-derived cell lines into blastula-stage embryos. Furthermore, we have established a fluorescent in vivo assay to monitor the developmental effects and fate of such transplanted cells using confocal laser scanning

  3. Detection of alloreactive T cells by flow cytometry : A new test compared with limiting dilution assay

    NARCIS (Netherlands)

    de Haan, A; van der Gun, [No Value; van der Bij, W; de Leij, LFMH; Prop, J

    2002-01-01

    Background. Frequencies of alloreactive T cells determined by limiting dilution assays (LDA) may not adequately reflect the donor-reactive immune status in transplant recipients. To reevaluate LDA frequencies, we developed a flow cytometry test for direct determination of alloreactive T-cell

  4. Inhibition of neuronal cell–cell adhesion measured by the microscopic aggregation assay and impedance sensing

    NARCIS (Netherlands)

    Wiertz, Remy; Marani, Enrico; Rutten, Wim

    2010-01-01

    Microscopic aggregation assay and impedance sensing (IS) were used to monitor a change in in vitro neuron–neuron adhesion in response to blocking of cell adhesion molecules. By blocking neuron–neuron adhesion, migration and aggregation of neuronal cells can be inhibited. This leads to better control

  5. Development of a partition-controlled dosing system for cell assays.

    NARCIS (Netherlands)

    Kramer, N.I.; Busser, F.J.M.; Oosterwijk, M.T.; Schirmer, K.; Escher, B.I.; Hermens, J.L.M.

    2010-01-01

    Hydrophobic and volatile chemicals have proven to be difficult to dose in cell assays. Cosolvents are often needed to dissolve these chemicals in cell culture medium. Moreover, the free concentration of these chemicals in culture medium may diminish over time due to metabolism, evaporation, and

  6. Micro-PIXE for single cell analysis

    International Nuclear Information System (INIS)

    Ortega, Richard

    2012-01-01

    The knowledge of the intracellular distribution of biological relevant metals is important to understand their mechanisms of action in cells, either for physiological, toxicological or pathological processes. However, the direct detection of trace metals in single cells is a challenging task that requires sophisticated analytical developments. The combination of micro-PIXE with RBS and STIM (Scanning Transmission Ion Microscopy) allows the quantitative determination of trace metal content within sub-cellular compartments. The application of STIM analysis provides high spatial resolution imaging (< 200 nm) and excellent mass sensitivity (< 0.1 ng). Application of the STIM-PIXE-RBS methodology is absolutely needed when organic mass loss appears during PIXE-RBS irradiation. This combination of STIM-PIXE-RBS provides fully quantitative determination of trace element content, expressed in μg/g, which is a quite unique capability for micro-PIXE compared to other micro-analytical methods such as the electron and synchrotron x-ray fluorescence. Examples of micro-PIXE studies for sub-cellular imaging of trace elements in various fields of interest will be presented: in patho-physiology of trace elements involved in neurodegenerative diseases such as Parkinson's disease, and in toxicology of metals such as cobalt. (author)

  7. Cell-mediated immune response in rotavirus-infected calves: leucocyte migration inhibition assay.

    Science.gov (United States)

    Chauhan, R S; Singh, N P

    1992-07-01

    The cell-mediated immune (CMI) response was determined in rotavirus-infected calves by leucocyte migration inhibition assay with blood, spleen, mesenteric lymph node and intestinal lymphocytes. The inhibition of migration was more prominent in intestinal and mesenteric lymph node lymphocytes than in spleen and blood. In rotavirus-infected calves, the assay indicated the presence of CMI response which was more prominent at the local site of infection.

  8. Recent Trends on Micro/Nanofluidic Single Cell Electroporation

    Directory of Open Access Journals (Sweden)

    Tuhin Subhra Santra

    2013-09-01

    Full Text Available The behaviors of cell to cell or cell to environment with their organelles and their intracellular physical or biochemical effects are still not fully understood. Analyzing millions of cells together cannot provide detailed information, such as cell proliferation, differentiation or different responses to external stimuli and intracellular reaction. Thus, single cell level research is becoming a pioneering research area that unveils the interaction details in high temporal and spatial resolution among cells. To analyze the cellular function, single cell electroporation can be conducted by employing a miniaturized device, whose dimension should be similar to that of a single cell. Micro/nanofluidic devices can fulfill this requirement for single cell electroporation. This device is not only useful for cell lysis, cell to cell fusion or separation, insertion of drug, DNA and antibodies inside single cell, but also it can control biochemical, electrical and mechanical parameters using electroporation technique. This device provides better performance such as high transfection efficiency, high cell viability, lower Joule heating effect, less sample contamination, lower toxicity during electroporation experiment when compared to bulk electroporation process. In addition, single organelles within a cell can be analyzed selectively by reducing the electrode size and gap at nanoscale level. This advanced technique can deliver (in/out biomolecules precisely through a small membrane area (micro to nanoscale area of the single cell, known as localized single cell membrane electroporation (LSCMEP. These articles emphasize the recent progress in micro/nanofluidic single cell electroporation, which is potentially beneficial for high-efficient therapeutic and delivery applications or understanding cell to cell interaction.

  9. Studies on a radioreceptor assay of prolactin using cell membrane fractions isolated from the rat liver

    International Nuclear Information System (INIS)

    Kato, Yuzuru; Oogo, Shozo

    1975-01-01

    Biologically active prolactin was determined by radioreceptor assay using the cell membrane fractions isolated from the rat liver. The quality and quantity of the receptor varied according to physiological conditions. Administration of estrogen was known to increase the amount of active prolactin, and pituitary hormones was presumed to have conributed to these processes. Prolactin binding to receptors in the receptor assay showed no dependency on the species specificity, but showed the cross-reaction with the prolactin of same biological activity. Prolactin receptor assay was expected to be an useful method to clarify the mechanism of prolactin function and its abnormality. (Mukohata, S.)

  10. Progress on the development of human in vitro dendritic cell based assays for assessment of the sensitizing potential of a compound

    International Nuclear Information System (INIS)

    Galvao dos Santos, G.; Reinders, J.; Ouwehand, K.; Rustemeyer, T.; Scheper, R.J.; Gibbs, S.

    2009-01-01

    Allergic contact dermatitis is the result of an adaptive immune response of the skin to direct exposure to an allergen. Since many chemicals are also allergens, European regulations require strict screening of all ingredients in consumer products. Until recently, identifying a potential allergen has completely relied on animal testing (e.g.: Local Lymph Node Assay). In addition to the ethical problems, both the 7th Amendment to the Cosmetics Directive and REACH have stimulated the development of alternative tests for the assessment of potential sensitizers. This review is aimed at summarising the progress on cell based assays, in particular dendritic cell based assays, being developed as animal alternatives. Primary cells (CD34 + derived dendritic cells, monocyte derived dendritic cells) as well as dendritic cell-like cell lines (THP-1, U-937, MUTZ-3, KG-1, HL-60, and K562) are extensively described along with biomarkers such as cell surface markers, cytokines, chemokines and kinases. From this review, it can be concluded that no single cell based assay nor single marker is yet able to distinguish all sensitizers from non-sensitizers in a test panel of chemicals, nor is it possible to rank the sensitizing potential of the test chemicals. This suggests that sensitivity and specificity may be increased by a tiered assay approach. Only a limited number of genomic and proteomic studies have been completed until now. Such studies have the potential to identify novel biomarkers for inclusion in future assay development. Although progress is promising, this review suggests that it may be difficult to meet the up and coming European regulatory deadlines.

  11. A molecular assay for sensitive detection of pathogen-specific T-cells.

    Directory of Open Access Journals (Sweden)

    Victoria O Kasprowicz

    Full Text Available Here we describe the development and validation of a highly sensitive assay of antigen-specific IFN-γ production using real time quantitative PCR (qPCR for two reporters--monokine-induced by IFN-γ (MIG and the IFN-γ inducible protein-10 (IP10. We developed and validated the assay and applied it to the detection of CMV, HIV and Mycobacterium tuberculosis (MTB specific responses, in a cohort of HIV co-infected patients. We compared the sensitivity of this assay to that of the ex vivo RD1 (ESAT-6 and CFP-10-specific IFN-γ Elispot assay. We observed a clear quantitative correlation between the two assays (P<0.001. Our assay proved to be a sensitive assay for the detection of MTB-specific T cells, could be performed on whole blood samples of fingerprick (50 uL volumes, and was not affected by HIV-mediated immunosuppression. This assay platform is potentially of utility in diagnosis of infection in this and other clinical settings.

  12. A novel cell exclusion zone assay with a barrier made from room temperature vulcanizing silicone rubber.

    Directory of Open Access Journals (Sweden)

    Yusuke Shiode

    Full Text Available To examine the usefulness of room temperature vulcanizing (RTV silicone rubber as a barrier material for cell exclusion zone assays.We created barriers using three types of RTV silicone rubber with differing viscosities. We then assessed the adherence of these barriers to culture dishes and their ease of removal from the dishes. We tested the effect of the newly created barriers on the extracellular matrix (ECM protein fibronectin by attaching and then removing them from fibronectin-coated culture dishes. We also conducted cell exclusion zone assays with MIO-M1 cells using this new barrier in order to measure cell migration. We used real time reverse transcription polymerase chain reaction (RT-PCR and immunohistochemical staining to measure the effect of fibronectin on MIO-M1 cell migration and the effect of migration (with fibronectin coating on basic fibroblast growth factor (bFGF expression in MIO-M1 cells.Of the three types of RTV silicon rubber tested, KE-3495-T was the best in terms of adherence to the dish and ease of removal from the dish. When barrier attachment and removal tests were performed, this rubber type did not have an effect on the fibronectin that coated the dish. In the cell exclusion assay, removal of the barrier revealed that a cell-free area with a distinct margin had been created, which allowed us to conduct a quantitative assessment of migration. Fibronectin significantly promoted the migration of MIO-M1 cells (P = 0.02. In addition, both real time RT-PCR and immunohistological staining indicated that bFGF expression in migrating MIO-M1 cells was significantly higher than that in non-migrating cells (P = 0.03.RTV silicone rubber can be used to create an effective barrier in cell exclusion zone assays and allows simple and low-cost multi-parametric analysis of cell migration.

  13. The Single Cell Proteome Project - Cell-Cycle Dependent Protein Expression in Breast Cancer Cell Lines

    National Research Council Canada - National Science Library

    Dovichi, Norman J

    2005-01-01

    .... Capillary sieving electrophoresis and capillary micellar electrophoresis were used to characterize proteins in single cells in one-dimensional separations, while the two techniques were combined...

  14. Improved detection of bovine viral diarrhea virus in bovine lymphoid cell lines using PrimeFlow RNA assay.

    Science.gov (United States)

    Falkenberg, Shollie M; Dassanayake, Rohana P; Neill, John D; Ridpath, Julia F

    2017-09-01

    Bovine viral diarrhea virus (BVDV) infections, whether as acute, persistent or contributing to co-infections, result in significant losses for cattle producers. Although, BVDV can be identified readily by real-time PCR and ELISA, detection and quantification of viral infection at the single cell level is extremely difficult. Detection at the single lymphoid cell level is important due to the immunomodulation that accompanies BVDV infection. A novel PrimeFlow RNA assay using in-situ detection of BVDV was evaluated. The model used to develop this technique included three BL-3 cell lines with different infection statuses, one not infected with BVDV, one infected with BVDV and one dual infected with BVDV and bovine leukosis virus. Using RNA probes specific for the BVDV-2a N pro -E rns coding region, BVDV RNA was detected from both contaminated BL-3 cell lines by flow cytometry and fluorescent microscopy. This is the first report on in-situ detection of BVDV at the single-cell level. Published by Elsevier Inc.

  15. High content screening for G protein-coupled receptors using cell-based protein translocation assays

    DEFF Research Database (Denmark)

    Grånäs, Charlotta; Lundholt, Betina Kerstin; Heydorn, Arne

    2005-01-01

    G protein-coupled receptors (GPCRs) have been one of the most productive classes of drug targets for several decades, and new technologies for GPCR-based discovery promise to keep this field active for years to come. While molecular screens for GPCR receptor agonist- and antagonist-based drugs...... will continue to be valuable discovery tools, the most exciting developments in the field involve cell-based assays for GPCR function. Some cell-based discovery strategies, such as the use of beta-arrestin as a surrogate marker for GPCR function, have already been reduced to practice, and have been used...... as valuable discovery tools for several years. The application of high content cell-based screening to GPCR discovery has opened up additional possibilities, such as direct tracking of GPCRs, G proteins and other signaling pathway components using intracellular translocation assays. These assays provide...

  16. Cytotoxicity screening of 23 engineered nanomaterials using a test matrix of ten cell lines and three different assays

    Directory of Open Access Journals (Sweden)

    Göbbert Christian

    2011-02-01

    Full Text Available Abstract Background Engineered nanomaterials display unique properties that may have impact on human health, and thus require a reliable evaluation of their potential toxicity. Here, we performed a standardized in vitro screening of 23 engineered nanomaterials. We thoroughly characterized the physicochemical properties of the nanomaterials and adapted three classical in vitro toxicity assays to eliminate nanomaterial interference. Nanomaterial toxicity was assessed in ten representative cell lines. Results Six nanomaterials induced oxidative cell stress while only a single nanomaterial reduced cellular metabolic activity and none of the particles affected cell viability. Results from heterogeneous and chemically identical particles suggested that surface chemistry, surface coating and chemical composition are likely determinants of nanomaterial toxicity. Individual cell lines differed significantly in their response, dependent on the particle type and the toxicity endpoint measured. Conclusion In vitro toxicity of the analyzed engineered nanomaterials cannot be attributed to a defined physicochemical property. Therefore, the accurate identification of nanomaterial cytotoxicity requires a matrix based on a set of sensitive cell lines and in vitro assays measuring different cytotoxicity endpoints.

  17. Cell-based potassium ion channel screening using the FluxOR assay.

    Science.gov (United States)

    Beacham, Daniel W; Blackmer, Trillium; O' Grady, Michael; Hanson, George T

    2010-04-01

    FluxOR technology is a cell-based assay used for high-throughput screening measurements of potassium channel activity. Using thallium influx as a surrogate indicator of potassium ion channel activity, the FluxOR Potassium Ion Channel Assay is based on the activation of a novel fluorescent dye. This indicator reports channel activity with a large fluorogenic response and is proportional to the number of open potassium channels on the cell, making it extremely useful for studying K(+) channel targets. In contrast to BTC-AM ester, FluxOR dye is roughly 10-fold more thallium sensitive, requiring much lower thallium for a larger signal window. This also means that the assay is carried out in a physiological, normal-chloride saline. In this article, the authors describe how they used BacMam gene delivery to express Kv7.2 and 7.3 (KCNQ), Kir2.1, or Kv11.1 (hERG) potassium ion channels in U2-OS cells. Using these cells, they ran the FluxOR assay to identify and characterize channel-specific inhibitory compounds discovered within the library (Tocriscreen Mini 1200 and Sigma Sodium/Potassium Modulators Ligand set). The FluxOR assay was able to identify several known specific inhibitors of Kv7.2/7.3 or hERG, highlighting its potential to identify novel and more efficacious small-molecule modulators.

  18. Digitizing Gold Nanoparticle-Based Colorimetric Assay by Imaging and Counting Single Nanoparticles.

    Science.gov (United States)

    Yuan, Liang; Wang, Xian; Fang, Yimin; Liu, Chenbin; Jiang, Dan; Wo, Xiang; Wang, Wei; Chen, Hong-Yuan

    2016-02-16

    Gold colloid changes its color when the internanoparticle distance changes. On the basis of analyte-induced aggregation or disaggregation behavior of gold nanoparticles (AuNPs), versatile colorimetric assays have been developed for measuring various kinds of analytes including proteins, DNA, small molecules, and ions. Traditional read-out signals, which are usually measured by a spectrometer or naked eyes, are based on the averaged extinction properties of a bulk solution containing billions of nanoparticles. Averaged extinction property of a large amount of nanoparticles diminished the contribution from rare events when the analyte concentration was low, thus resulting in limited detection sensitivity. Instead of measuring the averaged optical property from bulk colloid, in the present work, we proposed a digital counterpart of the colorimetric assay by imaging and counting individual AuNPs. This method quantified the analyte concentration with the number percentage of large-sized AuNPs aggregates, which were digitally counted with surface plasmon resonance microscopy (SPRM), a plasmonic imaging technique recently developed by us and other groups. SPRM was able to identify rare AuNPs aggregates despite their small population and greatly improved the detection sensitivity as demonstrated by two model systems based on analyte-induced aggregation and disaggregation, respectively. Furthermore, besides plasmonic AuNPs, SPRM is also suitable for imaging and counting nonplasmonic nanomaterials such as silica and metal oxide with poor extinction properties. It is thus anticipated that the present digitized assay holds a great potential for expanding the colorimetric assay to broad categories of nonplasmonic nanoparticles.

  19. Design and Analysis of Single-Cell Sequencing Experiments

    NARCIS (Netherlands)

    Grün, Dominic; van Oudenaarden, Alexander

    2015-01-01

    Recent advances in single-cell sequencing hold great potential for exploring biological systems with unprecedented resolution. Sequencing the genome of individual cells can reveal somatic mutations and allows the investigation of clonal dynamics. Single-cell transcriptome sequencing can elucidate

  20. Flow cytometric assay detecting cytotoxicity against human endogenous retrovirus antigens expressed on cultured multiple sclerosis cells

    DEFF Research Database (Denmark)

    Møller-Larsen, A; Brudek, T; Petersen, T

    2013-01-01

    expressing increased amounts of human endogenous retrovirus antigens. MS patients also have increased antibody levels to these antigens. The target cells are spontaneously growing peripheral blood mononuclear cells (PBMCs) of B cell lineage, expressing human endogenous retrovirus HERV epitopes...... on their surface. Polyclonal antibodies against defined peptides in the Env- and Gag-regions of the HERVs were raised in rabbits and used in antibody-dependent cell-mediated cytotoxicity (ADCC) -assays. Rituximab® (Roche), a chimeric monoclonal antibody against CD20 expressed primarily on B cells, was used...

  1. Sensing and Sensibility: Single-Islet-based Quality Control Assay of Cryopreserved Pancreatic Islets with Functionalized Hydrogel Microcapsules.

    Science.gov (United States)

    Chen, Wanyu; Shu, Zhiquan; Gao, Dayong; Shen, Amy Q

    2016-01-21

    Despite decades of research and clinical studies of islet transplantations, finding simple yet reliable islet quality assays that correlate accurately with in vivo potency is still a major challenge, especially for real-time and single-islet-based quality assessment. Herein, proof-of-concept studies of a cryopreserved microcapsule-based quality control assays are presented for single islets. Individual rat pancreatic islets and fluorescent oxygen-sensitive dye (FOSD) are encapsulated in alginate hydrogel microcapsules via a microfluidic device. To test the susceptibility of the microcapsules and the FOSD to cryopreservation, the islet microcapsules containing FOSD are cryopreserved and the islet functionalities (adenosine triphosphate, static insulin release measurement, and oxygen consumption rate) are assessed after freezing and thawing steps. The cryopreserved islet capsules with FOSD remain functional after encapsulation and freezing/thawing procedures, validating a simple yet reliable individual-islet-based quality control method for the entire islet processing procedure prior to transplantation. This work also demonstrates that the functionality of cryopreserved islets can be improved by introducing trehalose into the routinely used cryoprotectant dimethyl sulfoxide. The functionalized alginate hydrogel microcapsules with embedded FOSD and optimized cryopreservation protocol presented in this work serve as a versatile islet quality assay and offer tremendous promise for tackling existing challenges in islet transplantation procedures. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A cell-based, high content screening assay reveals activators and inhibitors of cancer cell invasion

    Science.gov (United States)

    Quintavalle, Manuela; Elia, Leonardo; Price, Jeffrey H.; Heynen-Genel, Susanne; Courtneidge, Sara A.

    2012-01-01

    Acquisition of invasive cell behavior underlies tumor progression and metastasis. To define in more molecular detail the mechanisms underlying invasive behavior, we developed a high throughput screening strategy to quantitate invadopodia; actin-rich membrane protrusions of cancer cells which contribute to tissue invasion and matrix remodeling. We developed a high content, imaged-based assay, and tested the LOPAC 1280 collection of pharmacologically active agents. We found compounds that potently inhibited invadopodia formation without overt toxicity, as well as compounds that increased invadopodia number. One of the two compounds that increased both invadopodia number and invasive behavior was the chemotherapeutic agent paclitaxel, which has potential clinical implications for its use in the neoadjuvant and resistance settings. Several of the invasion inhibitors were annotated as cyclin-dependent kinase (cdk) inhibitors. Loss-of-function experiments determined that Cdk5 was the relevant target. We further determined that the mechanism by which Cdk5 promotes both invadopodia formation and cancer invasion is by phosphorylation and down regulation of the actin regulatory protein caldesmon. PMID:21791703

  3. Single cell array impedance analysis in a microfluidic device

    Science.gov (United States)

    Altinagac, Emre; Taskin, Selen; Kizil, Huseyin

    2016-10-01

    Impedance analysis of single cells is presented in this paper. Following the separation of a target cell type by dielectrophoresis in our previous work, this paper focuses on capturing the cells as a single array and performing impedance analysis to point out the signature difference between each cell type. Lab-on-a-chip devices having a titanium interdigitated electrode layer on a glass substrate and a PDMS microchannel are fabricated to capture each cell in a single form and perform impedance analysis. HCT116 (homosapiens colon colorectal carcin) and HEK293 (human embryonic kidney) cells are used in our experiments.

  4. Development of a single-antigen magnetic bead assay (SAMBA) for the sensitive detection of HPA-1a alloantibodies using tag-engineered recombinant soluble β3 integrin.

    Science.gov (United States)

    Skaik, Younis; Battermann, Anja; Hiller, Oliver; Meyer, Oliver; Figueiredo, Constanca; Salama, Abdulgabar; Blasczyk, Rainer

    2013-05-31

    Timely and accurate testing for human platelet antigen 1a (HPA-1a) alloantibodies is vital for clinical diagnosis of neonatal alloimmune thrombocytopenia (NAIT). Current antigen-specific assays used for the detection of HPA-1 alloantibodies are technically very complex and cumbersome for most diagnostic laboratories. Hence, we designed and applied recombinant soluble (rs) β3 integrins displaying HPA-1a or HPA-1b epitopes for the development of a single-antigen magnetic bead assay (SAMBA). Soluble HPA-1a and HPA-1b were produced recombinantly in human embryonic kidney 293 (HEK293) cells and differentially tagged. The recombinant soluble proteins were then immobilized onto paramagnetic beads and used for analysis of HPA-1 alloantibodies by enzyme-linked immunosorbent assay (ELISA). HPA-1a serum samples (n=7) from NAIT patients, inert sera and sera containing non-HPA-1a antibodies were used to evaluate the sensitivity and specificity of the SAMBA. Fusion of V5-His or GS-SBP-His tags to the rsβ3 integrins resulted in high-yield expression. SAMBA was able to detect all HPA-1a and -1b alloantibodies recognized by monoclonal antibody-specific immobilization of platelet antigens assay (MAIPA). No cross-reactions between the sera were observed. Two out of seven of the HPA-1a alloantibody-containing sera demonstrated weak to moderate reactivity in MAIPA but strong signals in SAMBA. SAMBA provides a very reliable method for the detection of HPA-1 antibodies with high specificity and sensitivity. This simple and rapid assay can be adapted for use in any routine laboratory and can be potentially adapted for use on automated systems. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Micro-fluidic module for blood cell separation for gene expression radiobiological assays

    International Nuclear Information System (INIS)

    Brengues, Muriel; Gu, Jian; Zenhausern, Frederic

    2015-01-01

    Advances in molecular techniques have improved discovery of biomarkers associated with radiation exposure. Gene expression techniques have been demonstrated as effective tools for biodosimetry, and different assay platforms with different chemistries are now available. One of the main challenges is to integrate the sample preparation processing of these assays into micro-fluidic platforms to be fully automated for point-of-care medical countermeasures in the case of a radiological event. Most of these assays follow the same workflow processing that comprises first the collection of blood samples followed by cellular and molecular sample preparation. The sample preparation is based on the specific reagents of the assay system and depends also on the different subsets of cells population and the type of biomarkers of interest. In this article, the authors present a module for isolation of white blood cells from peripheral blood as a prerequisite for automation of gene expression assays on a micro-fluidic cartridge. For each sample condition, the gene expression platform can be adapted to suit the requirements of the selected assay chemistry (authors)

  6. A simple, versatile and sensitive cell-based assay for prions from various species.

    Directory of Open Access Journals (Sweden)

    Zaira E Arellano-Anaya

    Full Text Available Detection and quantification of prion infectivity is a crucial step for various fundamental and applied aspects of prion research. Identification of cell lines highly sensitive to prion infection led to the development of cell-based titration procedures aiming at replacing animal bioassays, usually performed in mice or hamsters. However, most of these cell lines are only permissive to mouse-adapted prions strains and do not allow titration of prions from other species. In this study, we show that epithelial RK13, a cell line permissive to mouse and bank vole prion strains and to natural prion agents from sheep and cervids, enables a robust and sensitive detection of mouse and ovine-derived prions. Importantly, the cell culture work is strongly reduced as the RK13 cell assay procedure designed here does not require subcultivation of the inoculated cultures. We also show that prions effectively bind to culture plastic vessel and are quantitatively detected by the cell assay. The possibility to easily quantify a wider range of prions, including rodent experimental strains but also natural agents from sheep and cervids, should prompt the spread of cell assays for routine prion titration and lead to valuable information in fundamental and applied studies.

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

    Science.gov (United States)

    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.

  8. Atomic force microscopy for the examination of single cell rheology.

    Science.gov (United States)

    Okajima, Takaharu

    2012-11-01

    Rheological properties of living cells play important roles in regulating their various biological functions. Therefore, measuring cell rheology is crucial for not only elucidating the relationship between the cell mechanics and functions, but also mechanical diagnosis of single cells. Atomic force microscopy (AFM) is becoming a useful technique for single cell diagnosis because it allows us to measure the rheological properties of adherent cells at any region on the surface without any modifications. In this review, we summarize AFM techniques for examining single cell rheology in frequency and time domains. Recent applications of AFM for investigating the statistical analysis of single cell rheology in comparison to other micro-rheological techniques are reviewed, and we discuss what specificity and universality of cell rheology are extracted using AFM.

  9. DeepCpG: accurate prediction of single-cell DNA methylation states using deep learning.

    Science.gov (United States)

    Angermueller, Christof; Lee, Heather J; Reik, Wolf; Stegle, Oliver

    2017-04-11

    Recent technological advances have enabled DNA methylation to be assayed at single-cell resolution. However, current protocols are limited by incomplete CpG coverage and hence methods to predict missing methylation states are critical to enable genome-wide analyses. We report DeepCpG, a computational approach based on deep neural networks to predict methylation states in single cells. We evaluate DeepCpG on single-cell methylation data from five cell types generated using alternative sequencing protocols. DeepCpG yields substantially more accurate predictions than previous methods. Additionally, we show that the model parameters can be interpreted, thereby providing insights into how sequence composition affects methylation variability.

  10. Cytotoxicity and genotoxicity assessment of Euphorbia hirta in MCF-7 cell line model using comet assay.

    Science.gov (United States)

    Ping, Kwan Yuet; Darah, Ibrahim; Chen, Yeng; Sasidharan, Sreenivasan

    2013-09-01

    To evaluate the cytotoxicity and genotoxicity activity of Euphorbia hirta (E. hirta) in MCF-7 cell line model using comet assay. The cytotoxicity of E. hirta extract was investigated by employing brine shrimp lethality assay and the genotoxicity of E. hirta was assessed by using Comet assay. Both toxicity tests exhibited significant toxicity result. In the comet assay, the E. hirta extract exhibited genotoxicity effects against MCF-7 DNA in a time-dependent manner by increasing mean percentage of DNA damage. The extract of E. hirta showed significant toxicity against brine shrimp with an LC₅₀ value of 620.382 µg/mL (24 h). Comparison with positive control potassium dichromate signifies that cytotoxicity exhibited by the methanol extract might have moderate activity. The present work confirmed the cytotoxicity and genotoxicity of E. hirta. However, the observed toxicity of E. hirta extracts needs to be confirmed in additional studies.

  11. Silicon Dioxide Thin Film Mediated Single Cell Nucleic Acid Isolation

    Science.gov (United States)

    Bogdanov, Evgeny; Dominova, Irina; Shusharina, Natalia; Botman, Stepan; Kasymov, Vitaliy; Patrushev, Maksim

    2013-01-01

    A limited amount of DNA extracted from single cells, and the development of single cell diagnostics make it necessary to create a new highly effective method for the single cells nucleic acids isolation. In this paper, we propose the DNA isolation method from biomaterials with limited DNA quantity in sample, and from samples with degradable DNA based on the use of solid-phase adsorbent silicon dioxide nanofilm deposited on the inner surface of PCR tube. PMID:23874571

  12. Plaque assay for human coronavirus NL63 using human colon carcinoma cells

    Directory of Open Access Journals (Sweden)

    Drosten Christian

    2008-11-01

    Full Text Available Abstract Background Coronaviruses cause a broad range of diseases in animals and humans. Human coronavirus (hCoV NL63 is associated with up to 10% of common colds. Viral plaque assays enable the characterization of virus infectivity and allow for purifying virus stock solutions. They are essential for drug screening. Hitherto used cell cultures for hCoV-NL63 show low levels of virus replication and weak and diffuse cytopathogenic effects. It has not yet been possible to establish practicable plaque assays for this important human pathogen. Results 12 different cell cultures were tested for susceptibility to hCoV-NL63 infection. Human colon carcinoma cells (CaCo-2 replicated virus more than 100 fold more efficiently than commonly used African green monkey kidney cells (LLC-MK2. CaCo-2 cells showed cytopathogenic effects 4 days post infection. Avicel, agarose and carboxymethyl-cellulose overlays proved suitable for plaque assays. Best results were achieved with Avicel, which produced large and clear plaques from the 4th day of infection. The utility of plaque assays with agrose overlay was demonstrated for purifying virus, thereby increasing viral infectivity by 1 log 10 PFU/mL. Conclusion CaCo-2 cells support hCoV-NL63 better than LLC-MK2 cells and enable cytopathogenic plaque assays. Avicel overlay is favourable for plaque quantification, and agarose overlay is preferred for plaque purification. HCoV-NL63 virus stock of increased infectivity will be beneficial in antiviral screening, animal modelling of disease, and other experimental tasks.

  13. Generation of TCR-engineered T cells and their use to control the performance of T cell assays.

    Science.gov (United States)

    Bidmon, Nicole; Attig, Sebastian; Rae, Richard; Schröder, Helene; Omokoko, Tana A; Simon, Petra; Kuhn, Andreas N; Kreiter, Sebastian; Sahin, Ugur; Gouttefangeas, Cécile; van der Burg, Sjoerd H; Britten, Cedrik M

    2015-06-15

    The systematic assessment of the human immune system bears huge potential to guide rational development of novel immunotherapies and clinical decision making. Multiple assays to monitor the quantity, phenotype, and function of Ag-specific T cells are commonly used to unravel patients' immune signatures in various disease settings and during therapeutic interventions. When compared with tests measuring soluble analytes, cellular immune assays have a higher variation, which is a major technical factor limiting their broad adoption in clinical immunology. The key solution may arise from continuous control of assay performance using TCR-engineered reference samples. We developed a simple, stable, robust, and scalable technology to generate reference samples that contain defined numbers of functional Ag-specific T cells. First, we show that RNA-engineered lymphocytes, equipped with selected TCRs, can repetitively deliver functional readouts of a controlled size across multiple assay platforms. We further describe a concept for the application of TCR-engineered reference samples to keep assay performance within or across institutions under tight control. Finally, we provide evidence that these novel control reagents can sensitively detect assay variation resulting from typical sources of error, such as low cell quality, loss of reagent stability, suboptimal hardware settings, or inaccurate gating. Copyright © 2015 by The American Association of Immunologists, Inc.

  14. Cell-based cytotoxicity assays for engineered nanomaterials safety screening: exposure of adipose derived stromal cells to titanium dioxide nanoparticles.

    Science.gov (United States)

    Xu, Yan; Hadjiargyrou, M; Rafailovich, Miriam; Mironava, Tatsiana

    2017-07-11

    Increasing production of nanomaterials requires fast and proper assessment of its potential toxicity. Therefore, there is a need to develop new assays that can be performed in vitro, be cost effective, and allow faster screening of engineered nanomaterials (ENMs). Herein, we report that titanium dioxide (TiO 2 ) nanoparticles (NPs) can induce damage to adipose derived stromal cells (ADSCs) at concentrations which are rated as safe by standard assays such as measuring proliferation, reactive oxygen species (ROS), and lactate dehydrogenase (LDH) levels. Specifically, we demonstrated that low concentrations of TiO 2 NPs, at which cellular LDH, ROS, or proliferation profiles were not affected, induced changes in the ADSCs secretory function and differentiation capability. These two functions are essential for ADSCs in wound healing, energy expenditure, and metabolism with serious health implications in vivo. We demonstrated that cytotoxicity assays based on specialized cell functions exhibit greater sensitivity and reveal damage induced by ENMs that was not otherwise detected by traditional ROS, LDH, and proliferation assays. For proper toxicological assessment of ENMs standard ROS, LDH, and proliferation assays should be combined with assays that investigate cellular functions relevant to the specific cell type.

  15. Evaluation of IRES-mediated, cell-type-specific cytotoxicity of poliovirus using a colorimetric cell proliferation assay.

    Science.gov (United States)

    Yang, Xiaoyi; Chen, Eying; Jiang, Hengguang; Muszynski, Karen; Harris, Raymond D; Giardina, Steven L; Gromeier, Matthias; Mitra, Gautam; Soman, Gopalan

    2009-01-01

    PVS-RIPO is a recombinant oncolytic poliovirus designed for clinical application to target CD155 expressing malignant gliomas and other malignant diseases. PVS-RIPO does not replicate in healthy neurons and is therefore non-pathogenic in rodent and non-human primate models of poliomyelitis. A tetrazolium salt dye-based cellular assay was developed and qualified to define the cytotoxicity of virus preparations on susceptible cells and to explore the target cell specificity of PVS-RIPO. In this assay, PVS-RIPO inhibited proliferation of U87-MG astrocytoma cells in a dose-dependent manner. However, HEK293 cells were much less susceptible to cell killing by PVS-RIPO. In contrast, the Sabin type 1 live attenuated poliovirus vaccine strain (PV(1)S) was cytotoxic to both HEK293 and U87-MG cells. The correlation between expression of CD155 and cytotoxicity was also explored using six different cell lines. There was little or no expression of CD155 and PVS-RIPO-induced cytotoxicity in Jurkat and Daudi cells. HEK293 was the only cell line tested that showed CD155 expression and resistance to PVS-RIPO cytotoxicity. The results indicate that differential cytotoxicity measured by the colorimetric assay can be used to evaluate the cytotoxicity and cell-type specificity of recombinant strains of poliovirus and to demonstrate lot to lot consistency during the manufacture of viruses intended for clinical use.

  16. High-dimensional single-cell cancer biology.

    Science.gov (United States)

    Irish, Jonathan M; Doxie, Deon B

    2014-01-01

    Cancer cells are distinguished from each other and from healthy cells by features that drive clonal evolution and therapy resistance. New advances in high-dimensional flow cytometry make it possible to systematically measure mechanisms of tumor initiation, progression, and therapy resistance on millions of cells from human tumors. Here we describe flow cytometry techniques that enable a "single-cell " view of cancer. High-dimensional techniques like mass cytometry enable multiplexed single-cell analysis of cell identity, clinical biomarkers, signaling network phospho-proteins, transcription factors, and functional readouts of proliferation, cell cycle status, and apoptosis. This capability pairs well with a signaling profiles approach that dissects mechanism by systematically perturbing and measuring many nodes in a signaling network. Single-cell approaches enable study of cellular heterogeneity of primary tissues and turn cell subsets into experimental controls or opportunities for new discovery. Rare populations of stem cells or therapy-resistant cancer cells can be identified and compared to other types of cells within the same sample. In the long term, these techniques will enable tracking of minimal residual disease (MRD) and disease progression. By better understanding biological systems that control development and cell-cell interactions in healthy and diseased contexts, we can learn to program cells to become therapeutic agents or target malignant signaling events to specifically kill cancer cells. Single-cell approaches that provide deep insight into cell signaling and fate decisions will be critical to optimizing the next generation of cancer treatments combining targeted approaches and immunotherapy.

  17. Autoradiographic assay of mutants resistant to diphtheria toxin in mammalian cells in vitro

    International Nuclear Information System (INIS)

    Ronen, A.; Gingerich, J.D.; Duncan, A.M.V.; Heddle, J.A.

    1984-01-01

    Diptheria toxin kills mammalian cells by ribosylating elongation factor 2, a protein factor necessary for protein synthesis. The frequency of cells able to form colonies in the presence of the toxin can be used as an assay for mutation to diphtheria toxin resistance. Resistance to diphtheria toxin can also be detected autoradiographically in cells exposed to [ 3 H]leucine after treatment with the toxin. In cultures of Chinese hamster ovary cells, the frequency of such resistant cells is increased by exposure of the cells to γ-rays, ultraviolet light, ethylnitrosourea, mitomycin c, ethidium bromide, and 5-bromo-2'-deoxyuridine in a dose- and time-dependent manner. The resistant cells form discrete microcolonies if they are allowed to divide several times before intoxication which indicates that they are genuine mutants. The assay is potentially adaptable to any cell population that can be intoxicated with diphtheria toxin and labeled with [ 3 H]leucine, whether or not the cells can form colonies. It may be useful, therefore, for measuring mutation rates in slowly growing or nondividing cell populations such as breast, brain, and liver, as well as in cells that do divide but cannot be readily cloned, such as the colonic epithelium. 23 references, 6 figures

  18. Aequorin as a bioluminescent indicator for use in the determination of biomolecules in single cells. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Sylvia Daunert

    2000-02-17

    During this funding period, the laboratories of Drs. Anderson and Daunert have performed a considerable amount of work toward addressing the issues associated with small volume analysis necessary for single cell studies. In that respect, their research has been focused on (1) developing new assays that can be miniaturized and are suitable for small volume and single cell analysis; (2) fabricating pL-vials that simulate the volume of single cells and setting up instrumentation capable of low-volume detection; (3) developing reproducible and reliable microinjection techniques; (4) developing methods of analysis for biomolecules in the pL-vials and employing these assays in the detection of biomolecules in single cells. The accomplishments attained in all these areas are described below. A total of 24 publications and 35 presentations have resulted from this work.

  19. A dual-docking microfluidic cell migration assay (D2-Chip) for testing neutrophil chemotaxis and the memory effect.

    Science.gov (United States)

    Yang, Ke; Wu, Jiandong; Xu, Guoqing; Xie, Dongxue; Peretz-Soroka, Hagit; Santos, Susy; Alexander, Murray; Zhu, Ling; Zhang, Michael; Liu, Yong; Lin, Francis

    2017-04-18

    Chemotaxis is a classic mechanism for guiding cell migration and an important topic in both fundamental cell biology and health sciences. Neutrophils are a widely used model to study eukaryotic cell migration and neutrophil chemotaxis itself can lead to protective or harmful immune actions to the body. While much has been learnt from past research about how neutrophils effectively navigate through a chemoattractant gradient, many interesting questions remain unclear. For example, while it is tempting to model neutrophil chemotaxis using the well-established biased random walk theory, the experimental proof was challenged by the cell's highly persistent migrating nature. A special experimental design is required to test the key predictions from the random walk model. Another question that has interested the cell migration community for decades concerns the existence of chemotactic memory and its underlying mechanism. Although chemotactic memory has been suggested in various studies, a clear quantitative experimental demonstration will improve our understanding of the migratory memory effect. Motivated by these questions, we developed a microfluidic cell migration assay (so-called dual-docking chip or D 2 -Chip) that can test both the biased random walk model and the memory effect for neutrophil chemotaxis on a single chip enabled by multi-region gradient generation and dual-region cell alignment. Our results provide experimental support for the biased random walk model and chemotactic memory for neutrophil chemotaxis. Quantitative data analyses provide new insights into neutrophil chemotaxis and memory by making connections to entropic disorder, cell morphology and oscillating migratory response.

  20. Mkit: A cell migration assay based on microfluidic device and smartphone.

    Science.gov (United States)

    Yang, Ke; Wu, Jiandong; Peretz-Soroka, Hagit; Zhu, Ling; Li, Zhigang; Sang, Yaoshuo; Hipolito, Jolly; Zhang, Michael; Santos, Susy; Hillier, Craig; de Faria, Ricardo Lobato; Liu, Yong; Lin, Francis

    2018-01-15

    Mobile sensing based on the integration of microfluidic device and smartphone, so-called MS 2 technology, has enabled many applications over recent years, and continues to stimulate growing interest in both research communities and industries. In particular, it has been envisioned that MS 2 technology can be developed for various cell functional assays to enable basic research and clinical applications. Toward this direction, in this paper, we describe the development of a MS 2 -based cell functional assay for testing cell migration (the M kit ). The system is constructed as an integrated test kit, which includes microfluidic chips, a smartphone-based imaging platform, the phone apps for image capturing and data analysis, and a set of reagent and accessories for performing the cell migration assay. We demonstrated that the M kit can effectively measure purified neutrophil and cancer cell chemotaxis. Furthermore, neutrophil chemotaxis can be tested from a drop of whole blood using the M kit with red blood cell (RBC) lysis. The effects of chemoattractant dose and gradient profile on neutrophil chemotaxis were also tested using the M kit . In addition to research applications, we demonstrated the effective use of the M kit for on-site test at the hospital and for testing clinical samples from chronic obstructive pulmonary disease patient. Thus, this developed M kit provides an easy and integrated experimental platform for cell migration related research and potential medical diagnostic applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. A Luminex-based single DNA fragment amplification assay as a practical tool for detecting and serotyping dengue virus.

    Science.gov (United States)

    Cabral-Castro, Mauro Jorge; Peralta, Regina Helena Saramago; Cavalcanti, Marta Guimarães; Puccioni-Sohler, Marzia; Carvalho, Valéria Lima; da Costa Vasconcelos, Pedro Fernando; Peralta, José Mauro

    2016-10-01

    Dengue is a mosquito-borne viral infection that can evolve from subclinical to severe forms of disease. Early recognition during initial primary and secondary infections correlates with a reduced case-fatality rate in susceptible groups. The aim of this study was to standardize a DNA hybridization assay based on the Luminex technology for detecting and serotyping dengue virus (DENV). Reference DENVs representing the four different serotypes were used as controls to standardize the test. For validation, 16 DENV isolates obtained from a reference laboratory were analyzed in a double-blind manner to validate the test. Sixty blood samples from patients suspected of having dengue fever were used to evaluate the methodology after the validation step, and the results were compared with the reference semi-nested RT-PCR. Additionally, five human samples of each Zika and Chikungunya confirmed patients were used for specificity analysis. The Luminex-based assay correctly identified all 16 DENV isolates. In the evaluation step, the results of the RT-PCR/Luminex assay showed a concordance of 86.7% with those of the semi-nested RT-PCR. None of other virus infection samples was amplified. This is the first description of a hybridization assay that can discriminate the four DENV serotypes using probes against a single DENV sequence. The results indicated that the RT-PCR/Luminex DENV assay designed and evaluated in this study is a valuable additional tool for the early and rapid detection and serotyping of DENV, which could, in the future, be applied to new targets such as the Zika and Chikungunya viruses. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Aquaporin-4 autoantibodies in neuromyelitis optica spectrum disorders: comparison between tissue-based and cell-based indirect immunofluorescence assays

    Directory of Open Access Journals (Sweden)

    Chan Koon H

    2010-09-01

    Full Text Available Abstract Background Neuromyelitis optica spectrum disorders (NMOSD are severe central nervous system inflammatory demyelinating disorders (CNS IDD characterized by monophasic or relapsing, longitudinally extensive transverse myelitis (LETM and/or optic neuritis (ON. A significant proportion of NMOSD patients are seropositive for aquaporin-4 (AQP4 autoantibodies. We compared the AQP4 autoantibody detection rates of tissue-based indirect immunofluorescence assay (IIFA and cell-based IIFA. Methods Serum of Chinese CNS IDD patients were assayed for AQP4 autoantibodies by tissue-based IIFA using monkey cerebellum and cell-based IIFA using transfected HEK293 cells which express human AQP4 on their cell membranes. Results In total, 128 CNS IDD patients were studied. We found that 78% of NMO patients were seropositive for AQP4 autoantibodies by cell-based IIFA versus 61% by tissue-based IFA (p = 0.250, 75% of patients having relapsing myelitis (RM with LETM were seropositive by cell-based IIFA versus 50% by tissue-based IIFA (p = 0.250, and 33% of relapsing ON patients were seropositive by cell-based IIFA versus 22% by tissue-based IIFA (p = 1.000; however the differences were not statistically significant. All patients seropositive by tissue-based IIFA were also seropositive for AQP4 autoantibodies by cell-based IIFA. Among 29 NMOSD patients seropositive for AQP4 autoantibodies by cell-based IIFA, 20 (69% were seropositive by tissue-based IIFA. The 9 patients seropositive by cell-based IIFA while seronegative by tissue-based IIFA had NMO (3, RM with LETM (3, a single attack of LETM (1, relapsing ON (1 and a single ON attack (1. Among 23 NMO or RM patients seropositive for AQP4 autoantibodies by cell-based IIFA, comparison between those seropositive (n = 17 and seronegative (n = 6 by tissue-based IIFA revealed no differences in clinical and neuroradiological characteristics between the two groups. Conclusion Cell-based IIFA is slightly more sensitive

  3. In vitro effect of X radiation on respiration and glycolysis of Ehrlich ascites carcinoma cells of the mouse - an experimental comparison with the mouse tumortetanus assay

    International Nuclear Information System (INIS)

    Negelein, E.; Schneeweiss, U.; Fabricius, E.M.; Akademie der Wissenschaften der DDR, Berlin. Zentralinstitut fuer Krebsforschung)

    1979-01-01

    Depending on the dose of X-rays, in vitro irradiation of Ehrlich ascites carcinoma cells of the mouse affected both respiration and glycolysis. 38.7 C/kg irradiation suppressed the aerobic and anaerobic energy metabolism rather strongly followed by a reduction of the 'take' and growth of the subcutaneously injected tumour cells, as opposed to the growth behavior of non-irradiated cells. In analogy, tetanus mortality rates were reduced in the mouse tumor-tetanus assay with 38.7 C/kg irradiated cells. On the other hand, irradiation with 5.16 C/kg of Ehrlich carcinoma cells resulted in unchanged rates of respiration and glycolysis, in spite of the strongly limited growth capacity of the tumor cells. The tumor-tetanus assay of the mouse showed good correlation with subcutaneous tumor growth; no such correlation was found in the tetanus assay and the manometric values of respiration and glycolysis with 5.16 C/kg irradiated tumor cells. After subcutaneous injection of mixed cell suspensions consisting of 1 x 10 5 viable and 1 x 10 6 38.7 C/kg irradiated Ehrlich ascites carcinoma cells as well as of 3 x 10 2 tetanus spores per single dose, we observed similar rates of tumor growth and tetanus mortality, respectively, if 1 x 10 5 viable tumor cells alone were administered together with 3 x 10 2 tetanus spores, without addition of irradiated tumor cells. (author)

  4. Implementation and Use of State-of-the-Art, Cell-Based In Vitro Assays.

    Science.gov (United States)

    Langer, Gernot

    2016-01-01

    The impressive advances in the generation and interpretation of functional omics data have greatly contributed to a better understanding of the (patho-)physiology of many biological systems and led to a massive increase in the number of specific targets and phenotypes to investigate in both basic and applied research. The obvious complexity revealed by these studies represents a major challenge to the research community and asks for improved target characterisation strategies with the help of reliable, high-quality assays. Thus, the use of living cells has become an integral part of many research activities because the cellular context more closely represents target-specific interrelations and activity patterns. Although still predominant, the use of traditional two-dimensional (2D) monolayer cell culture models has been gradually complemented by studies based on three-dimensional (3D) spheroid (Sutherland 1988) and other 3D tissue culture systems (Santos et al. 2012; Matsusaki et al. 2014) in an attempt to employ model systems more closely representing the microenvironment of cells in the body. Hence, quite a variety of state-of-the-art cell culture models are available for the generation of novel chemical probes or the identification of starting points for drug development in translational research and pharma drug discovery. In order to cope with these information-rich formats and their increasing technical complexity, cell-based assay development has become a scientific research topic in its own right and is used to ensure the provision of significant, reliable and high-quality data outlasting any discussions related to the current "irreproducibility epidemic" (Dolgin 2014; Prinz et al. 2011; Schatz 2014). At the same time the use of cells in microplate assay formats has become state of the art and greatly facilitates rigorous cell-based assay development by providing the researcher with the opportunity to address the multitude of factors affecting the actual

  5. A comparative study of Mono Mac 6 cells, isolated mononuclear cells and Limulus amoebocyte lysate assay in pyrogen testing

    DEFF Research Database (Denmark)

    Moesby, Lise; Jensen, S; Hansen, E W

    1999-01-01

    ) and Staphylococcus aureus was comparable to that of MNC. Aspergillus niger and Candida albicans induced IL-6 in isolated MNC, but not in MM6. The detection limit for Salmonella typhimurium in the MM6 assay was comparable to that of the LAL assay. As expected, S. aureus and C. albicans did not show any LAL activity......Pyrogen induced secretion of interleukin 6 (IL-6) in Mono Mac 6 (MM6) cells was measured. The ability of the MM6 cell culture to detect pyrogens was compared to the Limulus amoebocyte lysate (LAL) test and isolated mononuclear cells (MNC). The detection limit of MM6 for lipopolysaccharide (LPS....... A. niger and Influenza virus showed some activity in the LAL test, but could not be detected by MM6 cells. In conclusion, the MM6 assay is a good supplement to the current pyrogen assays for detection of LPS, S. aureus and S. typhimurium, but the MM6 assay could not detect A. niger, C. albicans...

  6. INFLUENCE OF TEMPERATURE ON AN ESTROGEN-RESPONSIVE RAINBOW TROUT CELL TRANSFECTION ASSAY

    Science.gov (United States)

    One uncertainty in extrapolating estrogenic effects in mammalian systems to those in fish and wildlife is the influence that temperature has on these effects. A reporter gene assay in cultured rainbow trout cell lines was used to determine the influence of temperature on the exp...

  7. Dendritic cell migration assay: a potential prediction model for identification of contact allergens.

    Science.gov (United States)

    Gibbs, Susan; Spiekstra, Sander; Corsini, Emanuela; McLeod, Julie; Reinders, Judith

    2013-04-01

    This manuscript describes methodology and a prediction model for the MUTZ-LC migration assay. The assay represents the physiological change in Langerhans cell (LC) behavior after exposure to a sensitizing chemical, resulting in LC migration from the epidermis to the dermis. MUTZ-LC are derived from the commercially available MUTZ-3 cell line. Upon exposure to a sensitizer MUTZ-LC migrate preferentially towards CXCL12 whereas upon exposure to a non-sensitizer MUTZ-LC migrate towards CCL5. A CXCL12/CCL5 ratio >1.10 in 2/3 independent experiments is indicative of a sensitizer, whereas a CXCL12/CCL5 ratio ≤1.10 is indicative of a non-sensitizer. At non cytotoxic chemical concentrations 9 sensitizers (2,4-dinitrochlorobenzene, paraphenylendiamine, cinnamaldehyde, isoeugenol, nickel-sulfate, tetramethylthiuram disulfide, eugenol, cinnamic-alcohol, ammonium-hexachloroplatinate) were distinguished from 4 non sensitizers (sodium lauryl sulfate, salicylic acid, phenol, octanoic acid). Critical points in assay performance are (i) MUTZ-3 passage number after thawing (p6-p40); (ii) cell viability (>80%); (iii) standard curve to optimize correlation of fluorescence with cell number; and (iv) optimization of the concentration of rhCXCL12 and rhCCL5 in transwell. The protocol has been tested in three European laboratories and results suggest that it may provide working conditions for performing the DC migration assay which is aimed at distinguishing sensitizers from non sensitizers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. A microfluidic wound-healing assay for quantifying endothelial cell migration

    NARCIS (Netherlands)

    van der Meer, Andries Dirk; Vermeul, Kim; Poot, Andreas A.; Feijen, Jan; Vermes, I.

    A microfluidic wound-healing assay for quantifying endothelial cell migration. Am J Physiol Heart Circ Physiol 298: H719–H725, 2010. First published November 20, 2009; doi:10.1152/ajpheart.00933.2009.—Endothelial migration is an important process in the formation of blood vessels and the repair of

  9. Optimization of Assays to Assess Dendritic Cell Activation and/or Energy in Ebola Infection

    Science.gov (United States)

    2011-10-01

    vaccines and therapeutics.  We developed and successfully employed assays to monitor attachment and entry of EBOV virus-like particles tagged with beta ... lactamase .  We demonstrated a strong preference for EBOV to enter macrophages and dendritic cells versus monocytes.  We provided evidence

  10. In vivo Comet assay – statistical analysis and power calculations of mice testicular cells

    DEFF Research Database (Denmark)

    Hansen, Merete Kjær; Sharma, Anoop Kumar; Dybdahl, Marianne

    2014-01-01

    -97-5, CAS no. 85-28-9, CAS no. 13674-87-8, CAS no. 43100-38-5 and CAS no. 60965-26-6. Testicular cells were examined using the alkaline version of the Comet assay and the DNA damage was quantified as % tail DNA using a fully automatic scoring system. From the raw data 23 summary statistics were examined...

  11. Phenotypic assay of adherent E. coli strains using hep-2 cells on ...

    African Journals Online (AJOL)

    In this paired case-control study of children with diarrhea in Rivers state, the association between HEp-2–adherent Escherichia coli strains and diarrhea was examined. Escherichia coli isolates from stool specimens of children with diarrhea were matched with controls and tested in HEp-2 cell adherence assay. A total of 266 ...

  12. Herpes simplex virus produces larger plaques when assayed on ultraviolet irradiated CV1 cells

    International Nuclear Information System (INIS)

    Coohill, T.P.; Babich, M.A.; Taylor, W.D.; Snipes, W.

    1980-01-01

    Plaque development for either untreated or UV treated irradiated Herpes simplex virus Type 1 was faster when assayed on UV irradiated CV1 cells. This Large Plaque Effect only occurred if a minimum delay of 12h between cell irradiation and viral inoculation was allowed. Shorter delays gave plaques that were smaller than controls (unirradiated virus-unirradiated cells). The effect was maximal for a 48-h delay and remained unchanged for delays as long as 84h. The effect was greatest for cell exposures of 10Jm -2 . (author)

  13. Acute shear stress direction dictates adherent cell remodeling and verifies shear profile of spinning disk assays

    International Nuclear Information System (INIS)

    Fuhrmann, Alexander; Engler, Adam J

    2015-01-01

    Several methods have been developed to quantify population level changes in cell attachment strength given its large heterogeneity. One such method is the rotating disk chamber or ‘spinning disk’ in which a range of shear forces are applied to attached cells to quantify detachment force, i.e. attachment strength, which can be heterogeneous within cell populations. However, computing the exact force vectors that act upon cells is complicated by complex flow fields and variable cell morphologies. Recent observations suggest that cells may remodel their morphology and align during acute shear exposure, but contrary to intuition, shear is not orthogonal to the radial direction. Here we theoretically derive the magnitude and direction of applied shear and demonstrate that cells, under certain physiological conditions, align in this direction within minutes. Shear force magnitude is also experimentally verified which validates that for spread cells shear forces and not torque or drag dominate in this assay, and demonstrates that the applied force per cell area is largely independent of initial morphology. These findings suggest that direct quantified comparison of the effects of shear on a wide array of cell types and conditions can be made with confidence using this assay without the need for computational or numerical modeling. (paper)

  14. High-efficiency single cell encapsulation and size selective capture of cells in picoliter droplets based on hydrodynamic micro-vortices.

    Science.gov (United States)

    Kamalakshakurup, Gopakumar; Lee, Abraham P

    2017-12-05

    Single cell analysis has emerged as a paradigm shift in cell biology to understand the heterogeneity of individual cells in a clone for pathological interrogation. Microfluidic droplet technology is a compelling platform to perform single cell analysis by encapsulating single cells inside picoliter-nanoliter (pL-nL) volume droplets. However, one of the primary challenges for droplet based single cell assays is single cell encapsulation in droplets, currently achieved either randomly, dictated by Poisson statistics, or by hydrodynamic techniques. In this paper, we present an interfacial hydrodynamic technique which initially traps the cells in micro-vortices, and later releases them one-to-one into the droplets, controlled by the width of the outer streamline that separates the vortex from the flow through the streaming passage adjacent to the aqueous-oil interface (d gap ). One-to-one encapsulation is achieved at a d gap equal to the radius of the cell, whereas complete trapping of the cells is realized at a d gap smaller than the radius of the cell. The unique feature of this technique is that it can perform 1. high efficiency single cell encapsulations and 2. size-selective capturing of cells, at low cell loading densities. Here we demonstrate these two capabilities with a 50% single cell encapsulation efficiency and size selective separation of platelets, RBCs and WBCs from a 10× diluted blood sample (WBC capture efficiency at 70%). The results suggest a passive, hydrodynamic micro-vortex based technique capable of performing high-efficiency single cell encapsulation for cell based assays.

  15. Mkit: A Cell Migration Assay Based on Microfluidic Device and Smartphone

    OpenAIRE

    Yang, Ke; Wu, Jiandong; Peretz-Soroka, Hagit; Zhu, Ling; Li, Zhigang; Sang, Yaoshuo; Hipolito, Jolly; Zhang, Michael; Santos, Susy; Hillier, Craig; de Faria, Ricardo Lobato; Liu, Yong; Lin, Francis

    2017-01-01

    Mobile sensing based on the integration of microfluidic device and smartphone, so-called MS2 technology, has enabled many applications over recent years, and continues to stimulate growing interest in both research communities and industries. In particular, it has been envisioned that MS2 technology can be developed for various cell functional assays to enable basic research and clinical applications. Toward this direction, in this paper, we describe the development of a MS2-based cell functi...

  16. Clinical Outcome Prediction Using Single-Cell Data.

    Science.gov (United States)

    Pouyan, Maziyar Baran; Jindal, Vasu; Nourani, Mehrdad

    2016-10-01

    Single-cell technologies like flow cytometry (FCM) provide valuable biological data for knowledge discovery in complex cellular systems like tissues and organs. FCM data contains multi-dimensional information about the cellular heterogeneity of intricate cellular systems. It is possible to correlate single-cell markers with phenotypic properties of those systems. Cell population identification and clinical outcome prediction from single-cell measurements are challenging problems in the field of single cell analysis. In this paper, we propose a hybrid learning approach to predict clinical outcome using samples' single-cell FCM data. The proposed method is efficient in both i) identification of cellular clusters in each sample's FCM data and ii) predict clinical outcome (healthy versus unhealthy) for each subject. Our method is robust and the experimental results indicate promising performance.

  17. Single-Cell Chemical Lysis on Microfluidic Chips with Arrays of Microwells

    Directory of Open Access Journals (Sweden)

    Nikolay A. Maslov

    2011-12-01

    Full Text Available Many conventional biochemical assays are performed using populations of cells to determine their quantitative biomolecular profiles. However, population averages do not reflect actual physiological processes in individual cells, which occur either on short time scales or nonsynchronously. Therefore, accurate analysis at the single-cell level has become a highly attractive tool for investigating cellular content. Microfluidic chips with arrays of microwells were developed for single-cell chemical lysis in the present study. The cellular occupancy in 30-mm-diameter microwells (91.45% was higher than that in 20-mm-diameter microwells (83.19% at an injection flow rate of 2.8 mL/min. However, most of the occupied 20-mm-diameter microwells contained individual cells. The results of chemical lysis experiments at the single-cell level indicate that cell membranes were gradually lysed as the lysis buffer was injected; they were fully lysed after 12 s. Single-cell chemical lysis was demonstrated in the proposed microfluidic chip, which is suitable for high-throughput cell lysis.

  18. Single molecule Raman spectroscopic assay to detect transgene from GM plants.

    Science.gov (United States)

    Kadam, Ulhas S; Chavhan, Rahul L; Schulz, Burkhard; Irudayaraj, Joseph

    2017-09-01

    Substantial concerns have been raised for the safety of transgenics on human health and environment. Many organizations, consumer groups, and environmental agencies advocate for stringent regulations to avoid transgene products' contamination in food cycle or in nature. Here we demonstrate a novel approach using surface enhanced Raman spectroscopy (SERS) to detect and quantify transgene from GM plants. We show a highly sensitive and accurate quantification of transgene DNA from multiple transgenic lines of Arabidopsis. The assay allows us to detect and quantify the transgenes as low as 0.10 pg without need for PCR-amplification. This technology is relatively cheap, quick, simple, and suitable for detection at low target concentration. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Research highlights: microfluidic-enabled single-cell epigenetics.

    Science.gov (United States)

    Dhar, Manjima; Khojah, Reem; Tay, Andy; Di Carlo, Dino

    2015-11-07

    Individual cells are the fundamental unit of life with diverse functions from metabolism to motility. In multicellular organisms, a single genome can give rise to tremendous variability across tissues at the single-cell level due to epigenetic differences in the genes that are expressed. Signals from the local environment or a history of signals can drive these variations, and tissues have many cell types that play separate roles. This epigenetic heterogeneity is of biological importance in normal functions such as tissue morphogenesis and can contribute to development or resistance of cancer, or other disease states. Therefore, an improved understanding of variations at the single cell level are fundamental to understanding biology and developing new approaches to combating disease. Traditional approaches to characterize epigenetic modifications of chromatin or the transcriptome of cells have often focused on blended responses of many cells in a tissue; however, such bulk measures lose spatial and temporal differences that occur from cell to cell, and cannot uncover novel or rare populations of cells. Here we highlight a flurry of recent activity to identify the mRNA profiles from thousands of single-cells as well as chromatin accessibility and histone marks on single to few hundreds of cells. Microfluidics and microfabrication have played a central role in the range of new techniques, and will likely continue to impact their further development towards routine single-cell epigenetic analysis.

  20. How Single-Cell Genomics Is Changing Evolutionary and Developmental Biology.

    Science.gov (United States)

    Marioni, John C; Arendt, Detlev

    2017-10-06

    The recent flood of single-cell data not only boosts our knowledge of cells and cell types, but also provides new insight into development and evolution from a cellular perspective. For example, assaying the genomes of multiple cells during development reveals developmental lineage trees-the kinship lineage-whereas cellular transcriptomes inform us about the regulatory state of cells and their gradual restriction in potency-the Waddington lineage. Beyond that, the comparison of single-cell data across species allows evolutionary changes to be tracked at all stages of development from the zygote, via different kinds of stem cells, to the differentiating cells. We discuss recent insights into the evolution of stem cells and initial attempts to reconstruct the evolutionary cell type tree of the mammalian forebrain, for example, by the comparative analysis of neuron types in the mesencephalic floor. These studies illustrate the immense potential of single-cell genomics to open up a new era in developmental and evolutionary research.

  1. Compare analysis for the nanotoxicity effects of different amounts of endocytic iron oxide nanoparticles at single cell level.

    Science.gov (United States)

    Huang, Chen-Yu; Ger, Tzong-Rong; Wei, Zung-Hang; Lai, Mei-Feng

    2014-01-01

    Developing methods that evaluate the cellular uptake of magnetic nanoparticles (MNPs) and nanotoxicity effects at single-cellular level are needed. In this study, magnetophoresis combining fluorescence based cytotoxicity assay was proposed to assess the viability and the single-cellular MNPs uptake simultaneously. Malignant cells (SKHep-1, HepG2, HeLa) were incubated with 10 nm anionic iron oxide nanoparticles. Prussian blue stain was performed to visualize the distribution of magnetic nanoparticles. MTT and fluorescence based assay analyzed the cytotoxicity effects of the bulk cell population and single cell, respectively. DAPI/PI stained was applied to evaluate death mechanism. The number of intracellular MNPs was found to be strongly correlated with the cell death. Significant differences between cellular MNP uptake in living and dead cells were observed. The method could be useful for future study of the nanotoxicity induced by MNPs.

  2. The quantitation of human growth hormone by a radioreceptor assay using an established human cell line

    International Nuclear Information System (INIS)

    Nederman, Thore; Sjoedin, Lars

    1987-01-01

    Membrane receptors on cultured human lymphocytes (IM-9) have been shown to bind human growth hormone (hGH) in a specific manner. The aim of the present study was to develop an in vitro assay of hGH based on this binding. The binding of [ 125 I]hGH was studied as a function of time, temperature, cell density, tracer concentration and the concentration of unlabelled hGH and other related hormones. Also, the dissociation of bound hGH and the chemical stability of hGH in the incubation medium were studied. From these studies, the conditions for an appropriate radioreceptor assay were determined. Briefly, 1.5-3.0 x 10 7 cells ml -1 were incubated with 5-20 x 10 -12 M [ 125 I]hGH and three different concentrations of unlabelled hGH chosen from the linear part of the [ 125 I]hGH displacement curve. The results were analyzed according to general pharmacopoeial principles. The mean values for growth hormone activity tested by radioreceptor assay were within the fiducial limits (P = 0.05) of the corresponding activity determined by the hypophysectomized rat body-weight gain assay. The in vitro assay was found to be more precise and less resource demanding than the in vivo bioassay of hGH. It is concluded that the in vitro bioassay described here is well suited as a screening method for potency determination of hGH preparations. (author)

  3. Quality Control Assays for Clinical-Grade Human Mesenchymal Stromal Cells: Methods for ATMP Release.

    Science.gov (United States)

    Radrizzani, Marina; Soncin, Sabrina; Lo Cicero, Viviana; Andriolo, Gabriella; Bolis, Sara; Turchetto, Lucia

    2016-01-01

    Mesenchymal stromal/stem cells (MSC) are promising candidates for the development of cell-based therapies for various diseases and are currently being evaluated in a number of clinical trials (Sharma et al., Transfusion 54:1418-1437, 2014; Ikebe and Suzuki, Biomed Res Int 2014:951512, 2014). MSC for therapeutic applications are classified as advanced therapy medicinal products (ATMP) (Regulation (EC) No 1394/2007 of the European Parliament and of the Council of 13 November 2007 on advanced therapy medicinal products and amending Directive 2001/83/EC and Regulation (EC) No 726/2004) and must be prepared according to good manufacturing practices ( http://ec.europa.eu/health/documents/eudralex/vol-4 ). They may be derived from different starting materials (mainly bone marrow (BM), adipose tissue, or cord blood) and applied as fresh or cryopreserved products, in the autologous as well as an allogeneic context (Sharma et al., Transfusion 54:1418-1437, 2014; Ikebe and Suzuki, Biomed Res Int 2014:951512, 2014; Sensebé and Bourin, Transplantation 87(9 Suppl):S49-S53, 2009). In any case, they require an approved and well-defined panel of assays in order to be released for clinical use.This chapter describes analytical methods implemented and performed in our cell factory as part of the release strategy for an ATMP consisting of frozen autologous BM-derived MSC. Such methods are designed to assess the safety (sterility, endotoxin, and mycoplasma assays) and identity/potency (cell count and viability, immunophenotype and clonogenic assay) of the final product. Some assays are also applied to the biological starting material (sterility) or carried out as in-process controls (sterility, cell count and viability, immunophenotype, clonogenic assay).The validation strategy for each analytical method is described in the accompanying Chapter 20 .

  4. Biology at a single cell level

    CSIR Research Space (South Africa)

    Mthunzi, P

    2012-10-01

    Full Text Available ://www.regenexx.com/wp-content/uploads/2011/05/IPS-cell-problems.jpg Induced pluripotent stem cells differentiated in culture http://www.youtube.com/watch?v=ECllrIzTKbA&feature=related Transfecting neuroblastomas Neuroblastoma ? Brain cells ? 80 ? 120 billion neurons in human... brain ? Non- renewing cell type ? Neurons difficult to transfect with established protocols ? Susceptible to degenerative disorders: - Parkinson?s disease - Multiple sclerosis - Alzheimer's disease http...

  5. Single cell electroporation using microfluidic devices

    NARCIS (Netherlands)

    le Gac, Severine; van den Berg, Albert; Lindstrom, S.; Andersson, Helene

    2012-01-01

    Electroporation is a powerful technique to increase the permeability of cell membranes and subsequently introduce foreign materials into cells. Pores are created in the cell membrane upon application of an electric fi eld (kV/cm). Most applications employ bulk electroporation, at the scale of 1 mL

  6. PRODt;CTION OF SINGLE CELL PROTEIN FROM BREWERY ...

    African Journals Online (AJOL)

    BSN

    The production of single cell protein (SCP) by the propagation of the yeast, Saccharomyces cerevisae ... animal feed but little or no information has been documented as per its explication for the production of single cell .... use of yeasts produced from vatious carbohydrate sources, molasses, sulphite liquors and vegetable.

  7. High content screening for G protein-coupled receptors using cell-based protein translocation assays

    DEFF Research Database (Denmark)

    Grånäs, Charlotta; Lundholt, Betina Kerstin; Heydorn, Arne

    2005-01-01

    G protein-coupled receptors (GPCRs) have been one of the most productive classes of drug targets for several decades, and new technologies for GPCR-based discovery promise to keep this field active for years to come. While molecular screens for GPCR receptor agonist- and antagonist-based drugs...... as valuable discovery tools for several years. The application of high content cell-based screening to GPCR discovery has opened up additional possibilities, such as direct tracking of GPCRs, G proteins and other signaling pathway components using intracellular translocation assays. These assays provide...

  8. A radiolabel-release microwell assay for proteolytic enzymes present in cell culture media

    International Nuclear Information System (INIS)

    Rucklidge, G.J.; Milne, G.

    1990-01-01

    A modified method for the measurement of proteolytic enzyme activity in cell culture-conditioned media has been developed. Using the release of 3H-labeled peptides from 3H-labeled gelatin the method is performed in microwell plates. The substrate is insolubilized and attached to the wells by glutaraldehyde treatment, thus eliminating the need for a precipitation step at the end of the assay. The assay is sensitive, reproducible, and convenient for small sample volumes. The effect of different protease inhibitors on activity can be assessed rapidly allowing an early characterization of the enzyme. It can also be adapted to microplate spectrophotometric analysis by staining residual substrate with Coomassie blue

  9. A single-centre evaluation of two new anti-Mullerian hormone assays and comparison with the current clinical standard assay.

    Science.gov (United States)

    Welsh, Paul; Smith, Karen; Nelson, Scott M

    2014-05-01

    Are the new Ansh Labs Ultra-Sensitive anti-Müllerian hormone (AMH) and picoAMH ELISA assays suitable for clinical use and is the Ultra-Sensitive assay comparable to the Beckman Coulter AMH Gen II assay? The Ultra-Sensitive assay appears to have different calibration to the Gen II assay, but has performance characteristics generally suitable for clinical use. The Gen II assay is the most commonly used AMH assay in routine biochemistry at present, but persistent calibration/interference problems have been reported. Serum from patients referred for AMH measurement was assayed (in duplicate) using the Gen II assay in Glasgow Royal Infirmary between January and February 2013. We randomly selected 193 stored serum samples to re-run (in duplicate) using the Ultra-Sensitive AMH Ansh Labs assay, blinded to the original result. Samples that returned low results were run on the picoAMH Ansh Labs assay. Performance characteristics and linearity of the new assays were also assessed. All serum samples from patients referred for AMH at Glasgow Royal Infirmary between January and February 2013 were eligible for inclusion. Investigators were blinded to any identifiable information regarding the patients, including sex, age and reason for AMH measurement. Intra-assay and inter-assay coefficients of variation of the Ultra-Sensitive and picoAMH assays were ≤6.0 and ≤10.7%, respectively, over a range of concentrations. The assays had mean linearity of 98 and 97% over the dilution range of 1:2-1:16 and 1:2-1:8, respectively. The limit of detection of the ultrasensitive assay was calculated to be 0.34 pmol/l. For 166 samples which provided a quantitative result on the Gen II and Ultra-Sensitive Ansh Labs assays, the median (interquartile range) was 12.2 (3.4-29.3) pmol/l and 20.0 (6.6-36.8) pmol/l, respectively (Py (Ultra-Sensitive) = 1.7 + 1.4 × Gen II. More samples were below the clinical cut-off of 5.4 pmol/l using the Gen II assay (a difference between paired proportions of 15

  10. Stem cell-like differentiation potentials of endometrial side population cells as revealed by a newly developed in vivo endometrial stem cell assay.

    Directory of Open Access Journals (Sweden)

    Kaoru Miyazaki

    Full Text Available Endometrial stem/progenitor cells contribute to the cyclical regeneration of human endometrium throughout a woman's reproductive life. Although the candidate cell populations have been extensively studied, no consensus exists regarding which endometrial population represents the stem/progenitor cell fraction in terms of in vivo stem cell activity. We have previously reported that human endometrial side population cells (ESP, but not endometrial main population cells (EMP, exhibit stem cell-like properties, including in vivo reconstitution of endometrium-like tissues when xenotransplanted into immunodeficient mice. The reconstitution efficiency, however, was low presumably because ESP cells alone could not provide a sufficient microenvironment (niche to support their stem cell activity. The objective of this study was to establish a novel in vivo endometrial stem cell assay employing cell tracking and tissue reconstitution systems and to examine the stem cell properties of ESP through use of this assay.ESP and EMP cells isolated from whole endometrial cells were infected with lentivirus to express tandem Tomato (TdTom, a red fluorescent protein. They were mixed with unlabeled whole endometrial cells and then transplanted under the kidney capsule of ovariectomized immunodeficient mice. These mice were treated with estradiol and progesterone for eight weeks and nephrectomized. All of the grafts reconstituted endometrium-like tissues under the kidney capsules. Immunofluorescence revealed that TdTom-positive cells were significantly more abundant in the glandular, stromal, and endothelial cells of the reconstituted endometrium in mice transplanted with TdTom-labeled ESP cells than those with TdTom-labeled EMP cells.We have established a novel in vivo endometrial stem cell assay in which multi-potential differentiation can be identified through cell tracking during in vivo endometrial tissue reconstitution. Using this assay, we demonstrated that ESP

  11. Biocompatibility of various ferrite nanoparticles evaluated by in vitro cytotoxicity assays using HeLa cells

    Science.gov (United States)

    Tomitaka, Asahi; Hirukawa, Atsuo; Yamada, Tsutomu; Morishita, Shin; Takemura, Yasushi

    2009-05-01

    Magnetic nanoparticles for thermotherapy must be biocompatible and possess high thermal efficiency as heating elements. The biocompatibility of Fe 3O 4 (20-30 nm), ZnFe 2O 4 (15-30 nm) and NiFe 2O 4 (20-30 nm) nanoparticles was studied using a cytotoxicity colony formation assay and a cell viability assay. The Fe 3O 4 sample was found to be biocompatible on HeLa cells. While ZnFe 2O 4 and NiFe 2O 4 were non-toxic at low concentrations, HeLa cells exhibited cytotoxic effects when exposed to concentrations of 100 μg/ml nanoparticles.

  12. Biocompatibility of various ferrite nanoparticles evaluated by in vitro cytotoxicity assays using HeLa cells

    Energy Technology Data Exchange (ETDEWEB)

    Tomitaka, Asahi [Department of Electrical and Computer Engineering, Yokohama National University, Tokiwadai 79-5, Yokohama, Kanagawa 240-8501 (Japan)], E-mail: d07gd158@ynu.ac.jp; Hirukawa, Atsuo; Yamada, Tsutomu [Department of Electrical and Computer Engineering, Yokohama National University, Tokiwadai 79-5, Yokohama, Kanagawa 240-8501 (Japan); Morishita, Shin [Department of Mechanical Engineering and Materials Science, Yokohama National University, Tokiwadai 79-5, Yokohama, Kanagawa 240-8501 (Japan); Takemura, Yasushi [Department of Electrical and Computer Engineering, Yokohama National University, Tokiwadai 79-5, Yokohama, Kanagawa 240-8501 (Japan)

    2009-05-15

    Magnetic nanoparticles for thermotherapy must be biocompatible and possess high thermal efficiency as heating elements. The biocompatibility of Fe{sub 3}O{sub 4} (20-30 nm), ZnFe{sub 2}O{sub 4} (15-30 nm) and NiFe{sub 2}O{sub 4} (20-30 nm) nanoparticles was studied using a cytotoxicity colony formation assay and a cell viability assay. The Fe{sub 3}O{sub 4} sample was found to be biocompatible on HeLa cells. While ZnFe{sub 2}O{sub 4} and NiFe{sub 2}O{sub 4} were non-toxic at low concentrations, HeLa cells exhibited cytotoxic effects when exposed to concentrations of 100 {mu}g/ml nanoparticles.

  13. Lack of genotoxicity of formocresol, paramonochlorophenol, and calcium hydroxide on mammalian cells by comet assay.

    Science.gov (United States)

    Ribeiro, Daniel Araki; Marques, Mariângela Esther Alencar; Salvadori, Daisy Maria Fávero

    2004-08-01

    Formocresol, paramonochlorophenol, and calcium hydroxide are widely used in dentistry because of their antibacterial activities in root canal disinfection. However, the results of genotoxicity studies using these materials are inconsistent in literature. The goal of this study was to examine the genotoxic potential of formocresol, paramonochlorophenol, and calcium hydroxide using mouse lymphoma cells and human fibroblasts cells in vitro by the comet assay. Data were assessed by Kruskal-Wallis nonparametric test. The results showed that all compounds tested did not cause DNA damage for the tail moment or tail intensity parameters. These findings suggest that formocresol, paramonochlorophenol, and calcium hydroxide do not promote DNA damage in mammalian cells and that the comet assay is a suitable tool to investigate genotoxicity.

  14. A Caco-2 cell-based quantitative antioxidant activity assay for antioxidants.

    Science.gov (United States)

    Wan, Hongxia; Liu, Dong; Yu, Xiangying; Sun, Haiyan; Li, Yan

    2015-05-15

    A Caco-2 cell-based antioxidant activity (CAA) assay for quantitative evaluation of antioxidants was developed by optimizing seeding density and culture time of Caco-2 cells, incubation time and concentration of fluorescent probe (2',7'-dichlorofluorescin diacetate, DCFH-DA), incubation way and incubation time of antioxidants (pure phytochemicals) and DCFH-DA with cells, and detection time of fluorescence. Results showed that the CAA assay was of good reproducibility and could be used to evaluate the antioxidant activity of antioxidants at the following conditions: seeding density of 5 × 10(4)/well, cell culture time of 24h, co-incubation of 60 μM DCFH-DA and pure phytochemicals with Caco-2 cells for 20 min and fluorescence recorded for 90 min. Additionally, a significant correlation was observed between CAA values and rat plasma ORAC values following the intake of antioxidants for selected pure phytochemicals (R(2) = 0.815, p < 0.01), demonstrating the good biological relevance of CAA assay. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Interference of single walled carbon nanotubes (SWCNT) in the measurement of lipid peroxidation in aquatic organisms through TBARS assay.

    Science.gov (United States)

    Monserrat, J M; Seixas, A L R; Ferreira-Cravo, M; Bürguer-Mendonça, M; Garcia, S C; Kaufmann, C G; Ventura-Lima, J

    2017-06-01

    Nanomaterials (NM) exhibit unique properties due their size and relative area, but the mechanisms and effects in the living organisms are yet to be unfold in their totality. Potential toxicity mechanisms concerning NM as carbon nanotubes include oxidative stress generation. Several fluorimetric and colorimetric methods have been systematically used to measure NM toxicity, and controversial results have been reported. One of the problems can be related to the interference effects induced by NM, leading to artifacts that can lead to misleading conclusions. In present study, it was performed in vitro assays with two aquatic species: the zebrafish Danio rerio and the polychaete Laeonereis acuta to evaluate the potential interference capacity of single-wall carbon nanotubes (SWCNT) in a fluorometric method (TBARS assay) to measure lipid peroxidation. Obtained results indicated that gills and brain of zebrafish presented a lowered fluorescence only at extremely high concentrations (50 and 500mg/L). Determinations in anterior, middle, and posterior body regions of L. acuta showed a quite different pattern: high fluorescence at low SWCNT concentrations (0.5mg/L) and lowering at the highest (500mg/L). To eliminate matrix effect of biological samples, tests employing the standard for TBARS assay, 1,3,3-tetramethoxipropane, were run and the results showed again higher fluorescence values at low concentrations (0.5-5mg SWCNT/L), a technique artifact that could lead to misleading conclusions since higher fluorescence values implicate higher TBARS concentration, implying oxidative stress. Using the colorimetric FOX assay with cumene hydroperoxide as standard presented remarkable better results since no artifacts were observed in the same SWCNT concentration range that employed with the TBARS technique. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Single-molecule tracking in living cells using single quantum dot applications.

    Science.gov (United States)

    Baba, Koichi; Nishida, Kohji

    2012-01-01

    Revealing the behavior of single molecules in living cells is very useful for understanding cellular events. Quantum dot probes are particularly promising tools for revealing how biological events occur at the single molecule level both in vitro and in vivo. In this review, we will introduce how single quantum dot applications are used for single molecule tracking. We will discuss how single quantum dot tracking has been used in several examples of complex biological processes, including membrane dynamics, neuronal function, selective transport mechanisms of the nuclear pore complex, and in vivo real-time observation. We also briefly discuss the prospects for single molecule tracking using advanced probes.

  17. A single-tube 27-plex SNP assay for estimating individual ancestry and admixture from three continents.

    Science.gov (United States)

    Wei, Yi-Liang; Wei, Li; Zhao, Lei; Sun, Qi-Fan; Jiang, Li; Zhang, Tao; Liu, Hai-Bo; Chen, Jian-Gang; Ye, Jian; Hu, Lan; Li, Cai-Xia

    2016-01-01

    A single-tube multiplex assay of a small set of ancestry-informative markers (AIMs) for effectively estimating individual ancestry and admixture is an ideal forensic tool to trace the population origin of an unknown DNA sample. We present a newly developed 27-plex single nucleotide polymorphism (SNP) panel with highly robust and balanced differential power to perfectly assign individuals to African, European, and East Asian ancestries. Evaluating 968 previously described intercontinental AIMs from three HapMap population genotyping datasets (Yoruban in Ibadan, Nigeria (YRI); Utah residents with Northern and Western European ancestry from the Centre de'Etude du Polymorphism Humain (CEPH) collection (CEU); and Han Chinese in Beijing, China (CHB)), the best set of markers was selected on the basis of Hardy-Weinberg equilibrium (p > 0.00001), population-specific allele frequency (two of three δ values >0.5), according to linkage disequilibrium (r (2) ancestry of the 11 populations in the HapMap project. Then, we tested the 27-plex SNP assay with 1164 individuals from 17 additional populations. The results demonstrated that the SNP panel was successful for ancestry inference of individuals with African, European, and East Asian ancestry. Furthermore, the system performed well when inferring the admixture of Eurasians (EUR/EAS) after analyzing admixed populations from Xinjiang (Central Asian) as follows: Tajik (68:27), Uyghur (49:46), Kirgiz (40:57), and Kazak (36:60). For individual analyses, we interpreted each sample with a three-ancestry component percentage and a population match probability sequence. This multiplex assay is a convenient and cost-effective tool to assist in criminal investigations, as well as to correct for the effects of population stratification for case-control studies.

  18. Single assay for simultaneous detection and differential identification of human and avian influenza virus types, subtypes, and emergent variants.

    Directory of Open Access Journals (Sweden)

    David Metzgar

    Full Text Available For more than four decades the cause of most type A influenza virus infections of humans has been attributed to only two viral subtypes, A/H1N1 or A/H3N2. In contrast, avian and other vertebrate species are a reservoir of type A influenza virus genome diversity, hosting strains representing at least 120 of 144 combinations of 16 viral hemagglutinin and 9 viral neuraminidase subtypes. Viral genome segment reassortments and mutations emerging within this reservoir may spawn new influenza virus strains as imminent epidemic or pandemic threats to human health and poultry production. Traditional methods to detect and differentiate influenza virus subtypes are either time-consuming and labor-intensive (culture-based or remarkably insensitive (antibody-based. Molecular diagnostic assays based upon reverse transcriptase-polymerase chain reaction (RT-PCR have short assay cycle time, and high analytical sensitivity and specificity. However, none of these diagnostic tests determine viral gene nucleotide sequences to distinguish strains and variants of a detected pathogen from one specimen to the next. Decision-quality, strain- and variant-specific pathogen gene sequence information may be critical for public health, infection control, surveillance, epidemiology, or medical/veterinary treatment planning. The Resequencing Pathogen Microarray (RPM-Flu is a robust, highly multiplexed and target gene sequencing-based alternative to both traditional culture- or biomarker-based diagnostic tests. RPM-Flu is a single, simultaneous differential diagnostic assay for all subtype combinations of type A influenza viruses and for 30 other viral and bacterial pathogens that may cause influenza-like illness. These other pathogen targets of RPM-Flu may co-infect and compound the morbidity and/or mortality of patients with influenza. The informative specificity of a single RPM-Flu test represents specimen-specific viral gene sequences as determinants of virus type, A

  19. A critical assessment of the use of microculture tetrazolium assays to measure cell growth and function.

    Science.gov (United States)

    Marshall, N J; Goodwin, C J; Holt, S J

    1995-06-01

    Microculture tetrazolium assays (MTAs) are being widely applied to probe the relationships between cell survival, growth, and differentiation and also to investigate associations between compromised cell metabolism, oxidative stress, and programmed cell death as occurs in apoptosis. MTAs rely upon the cellular reduction of tetrazolium salts to their intensely coloured formazans. The resulting colorimetric assays form the basis of exceptionally precise systems which are technically amenable and capable of a high throughput of samples. As a consequence, MTAs are being used to monitor responses to both extracellular activators and toxic agents in disciplines as diverse as radiobiology and endocrinology. We review the chemistry and histochemical applications of tetrazolium salts and subsequently discuss the criteria for their use in MTAs. These assays are one of the latest examples of the application of the tetrazolium/formazan system to cell biology. We outline current views on the mechanisms of the bioreduction of tetrazolium salts. These probably combine to reflect the integrated pyridine nucleotide dependent redox state of the cell. We try to illustrate how an understanding of these mechanisms helps to avoid some of the pitfalls of the MTA systems. There is now for example, extensive evidence that changes in cell culture environments, such as glucose supply or pH of the medium, influence the reduction of tetrazolium salts and thereby introduce artefacts into MTAs. Finally, we provide examples of situations in which MTAs can be used to complement other more established experimental systems. They then act as unique probes with which to investigate changes in the redox state of the cell. These changes are associated with regulation of cell growth, proliferation and differentiation and conversely, the different pathways leading to cell death.

  20. Single cell dual adherent-suspension co-culture micro-environment for studying tumor-stromal interactions with functionally selected cancer stem-like cells.

    Science.gov (United States)

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

    2016-08-07

    Considerable evidence suggests that cancer stem-like cells (CSCs) are critical in tumor pathogenesis, but their rarity and transience has led to much controversy about their exact nature. Although CSCs can be functionally identified using dish-based tumorsphere assays, it is difficult to handle and monitor single cells in dish-based approaches; single cell-based microfluidic approaches offer better control and reliable single cell derived sphere formation. However, like normal stem cells, CSCs are heavily regulated by their microenvironment, requiring tumor-stromal interactions for tumorigenic and proliferative behaviors. To enable single cell derived tumorsphere formation within a stromal microenvironment, we present a dual adherent/suspension co-culture device, which combines a suspension environment for single-cell tumorsphere assays and an adherent environment for co-culturing stromal cells in close proximity by selectively patterning polyHEMA in indented microwells. By minimizing dead volume and improving cell capture efficiency, the presented platform allows for the use of small numbers of cells (<100 cells). As a proof of concept, we co-cultured single T47D (breast cancer) cells and primary cancer associated fibroblasts (CAF) on-chip for 14 days to monitor sphere formation and growth. Compared to mono-culture, co-cultured T47D have higher tumorigenic potential (sphere formation rate) and proliferation rates (larger sphere size). Furthermore, 96-multiplexed single-cell transcriptome analyses were performed to compare the gene expression of co-cultured and mono-cultured T47D cells. Phenotypic changes observed in co-culture correlated with expression changes in genes associated with proliferation, apoptotic suppression, tumorigenicity and even epithelial-to-mesechymal transition. Combining the presented platform with single cell transcriptome analysis, we successfully identified functional CSCs and investigated the phenotypic and transcriptome effects induced

  1. X-ray microanalysis of single and cultured cells

    International Nuclear Information System (INIS)

    Wroblewski, J.; Roomans, G.M.

    1984-01-01

    X-ray microanalysis of single or cultured cells is often a useful alternative or complement to the analysis of the corresponding tissue. It also allows the analysis of individual cells in a cell population. Preparation for X-ray microanalysis poses a number of typical problems. Suspensions of single cells can be prepared by either of two pathways: (1) washing - mounting - drying, or (2) centrifugation - freezing or fixation - sectioning. The washing step in the preparation of single or cultured cells presents the most severe problems. Cultured cells are generally grown on a substrate that is compatible with both the analysis and the culture, washed and dried. In some cases, sectioning of cultured cell monolayers has been performed. Special problems in quantitative analysis occur in those cases where the cells are analyzed on a thick substrate, since the substrate contributes to the spectral background

  2. Simultaneous Multiplexed Measurement of RNA and Proteins in Single Cells

    Directory of Open Access Journals (Sweden)

    Spyros Darmanis

    2016-01-01

    Full Text Available Significant advances have been made in methods to analyze genomes and transcriptomes of single cells, but to fully define cell states, proteins must also be accessed as central actors defining a cell’s phenotype. Methods currently used to analyze endogenous protein expression in single cells are limited in specificity, throughput, or multiplex capability. Here, we present an approach to simultaneously and specifically interrogate large sets of protein and RNA targets in lysates from individual cells, enabling investigations of cell functions and responses. We applied our method to investigate the effects of BMP4, an experimental therapeutic agent, on early-passage glioblastoma cell cultures. We uncovered significant heterogeneity in responses to treatment at levels of RNA and protein, with a subset of cells reacting in a distinct manner to BMP4. Moreover, we found overall poor correlation between protein and RNA at the level of single cells, with proteins more accurately defining responses to treatment.

  3. Single-cell technologies to study the immune system.

    Science.gov (United States)

    Proserpio, Valentina; Mahata, Bidesh

    2016-02-01

    The immune system is composed of a variety of cells that act in a coordinated fashion to protect the organism against a multitude of different pathogens. The great variability of existing pathogens corresponds to a similar high heterogeneity of the immune cells. The study of individual immune cells, the fundamental unit of immunity, has recently transformed from a qualitative microscopic imaging to a nearly complete quantitative transcriptomic analysis. This shift has been driven by the rapid development of multiple single-cell technologies. These new advances are expected to boost the detection of less frequent cell types and transient or intermediate cell states. They will highlight the individuality of each single cell and greatly expand the resolution of current available classifications and differentiation trajectories. In this review we discuss the recent advancement and application of single-cell technologies, their limitations and future applications to study the immune system. © 2015 The Authors. Immunology Published by John Wiley & Sons Ltd.

  4. High-throughput single-cell manipulation in brain tissue.

    Directory of Open Access Journals (Sweden)

    Joseph D Steinmeyer

    Full Text Available The complexity of neurons and neuronal circuits in brain tissue requires the genetic manipulation, labeling, and tracking of single cells. However, current methods for manipulating cells in brain tissue are limited to either bulk techniques, lacking single-cell accuracy, or manual methods that provide single-cell accuracy but at significantly lower throughputs and repeatability. Here, we demonstrate high-throughput, efficient, reliable, and combinatorial delivery of multiple genetic vectors and reagents into targeted cells within the same tissue sample with single-cell accuracy. Our system automatically loads nanoliter-scale volumes of reagents into a micropipette from multiwell plates, targets and transfects single cells in brain tissues using a robust electroporation technique, and finally preps the micropipette by automated cleaning for repeating the transfection cycle. We demonstrate multi-colored labeling of adjacent cells, both in organotypic and acute slices, and transfection of plasmids encoding different protein isoforms into neurons within the same brain tissue for analysis of their effects on linear dendritic spine density. Our platform could also be used to rapidly deliver, both ex vivo and in vivo, a variety of genetic vectors, including optogenetic and cell-type specific agents, as well as fast-acting reagents such as labeling dyes, calcium sensors, and voltage sensors to manipulate and track neuronal circuit activity at single-cell resolution.

  5. High-content image analysis (HCIA) assay has the highest correlation with direct counting cell suspension compared to the ATP, WST-8 and Alamar blue assays for measurement of cytotoxicity.

    Science.gov (United States)

    Tahara, Haruna; Matsuda, Shun; Yamamoto, Yusuke; Yoshizawa, Hiroe; Fujita, Masaharu; Katsuoka, Yasuhiro; Kasahara, Toshihiko

    2017-11-01

    Various cytotoxicity assays measuring indicators such as enzyme activity, dye uptake, or cellular ATP content are often performed using 96-well microplates. However, recent reports show that cytotoxicity assays such as the ATP assay and MTS assay underestimate cytotoxicity when compounds such as anti-cancer drugs or mutagens induce cell hypertrophy whilst increasing intracellular ATP content. Therefore, we attempted to evaluate the reliability of a high-content image analysis (HCIA) assay to count cell number in a 96-well microplate automatically without using a cell-number indicator. We compared cytotoxicity results of 25 compounds obtained from ATP, WST-8, Alamar blue, and HCIA assays with those directly measured using an automatic cell counter, and repeating individual experiments thrice. The number of compounds showing low correlation in cell viability measured using cytotoxicity assays compared to automatic cell counting (r 2 cytotoxicity assay, 0. Compounds for which correlation was poor in 3 assays, except the HCIA assay, induced an increase in nuclear and cell size. However, correlation between cell viability measured by automatic cell counter and the HCIA assay was strong regardless of nuclear and cell size. Additionally, correlation coefficients between IC 50 values obtained from automatic cell counter and from cytotoxicity assays were as follows: ATP assay, 0.80; WST-8 assay, 0.84; Alamar blue assay, 0.84; and HCIA assay, 0.98. From the above, we showed that the HCIA cytotoxicity assay produces similar data to the automatic cell counter and is highly accurate in measuring cytotoxicity. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Development of a multiplex PCR assay for characterization of embryonic stem cells.

    Science.gov (United States)

    Pal, Rajarshi; Mamidi, Murali Krishna; Das, Anjan Kumar; Rao, Mahendra; Bhonde, Ramesh

    2013-01-01

    Several molecular methods like real-time PCR (Q-PCR), expression sequence tag (EST) scan, microarray and microRNA analysis, and massively parallel signature sequencing (MPSS) have proved to be increasingly sensitive and efficient for monitoring human embryonic stem cell (hESC) differentiation. However, most of these high-throughput tests have a limited use due to high cost, extended turnaround time, and the involvement of highly specialized technical expertise. Hence, there is a need of rapid, cost-effective, robust, yet sensitive method for routine screening of hESCs. A critical requirement in hESC cultures is to maintain a uniform undifferentiated state and to determine their differentiation capacity by showing the expression of germ-layer-specific gene markers. To determine the modulation of gene expression in hESCs during propagation, expansion, and differentiation via embryoid body (EB) formation, we developed a simple, rapid, inexpensive, and definitive multimarker, semiquantitative multiplex RT-PCR (mxPCR) platform technology. Among the 15 gene primers tested, 4 were pluripotent markers comprising of set 1; and 3 lineage-specific markers from each ecto-, meso-, and endoderm layers were combined as sets 2, 3, and 4, respectively. In summary, this study was performed to characterize hESCs on a molecular level and to determine the quality and degree of variability among hESC and their early progenies (EB). This single-reaction mxPCR assay was flexible and, by selecting appropriate reporter genes, can be designed for characterization of different hESC lines during routine maintenance and directed differentiation.

  7. Measurement of circulating cell-derived microparticles by flow cytometry: sources of variability within the assay.

    Science.gov (United States)

    Ayers, Lisa; Kohler, Malcolm; Harrison, Paul; Sargent, Ian; Dragovic, Rebecca; Schaap, Marianne; Nieuwland, Rienk; Brooks, Susan A; Ferry, Berne

    2011-04-01

    Circulating cell-derived microparticles (MPs) have been implicated in several disease processes and elevated levels are found in many pathological conditions. The detection and accurate measurement of MPs, although attracting widespread interest, is hampered by a lack of standardisation. The aim of this study was to establish a reliable flow cytometric assay to measure distinct subtypes of MPs in disease and to identify any significant causes of variability in MP quantification. Circulating MPs within plasma were identified by their phenotype (platelet, endothelial, leukocyte and annexin-V positivity (AnnV+). The influence of key variables (i.e. time between venepuncture and centrifugation, washing steps, the number of centrifugation steps, freezing/long-term storage and temperature of thawing) on MP measurement were investigated. Increasing time between venepuncture and centrifugation leads to increased MP levels. Washing samples results in decreased AnnV+MPs (P=0.002) and platelet-derived MPs (PMPs) (P=0.002). Double centrifugation of MPs prior to freezing decreases numbers of AnnV+MPs (P=0.0004) and PMPs (P=0.0004). A single freeze thaw cycle of samples led to an increase in AnnV+MPs (P=0.0020) and PMPs (P=0.0039). Long-term storage of MP samples at -80° resulted in decreased MP levels. This study found that minor protocol changes significantly affected MP levels. This is one of the first studies attempting to standardise a method for obtaining and measuring circulating MPs. Standardisation will be essential for successful development of MP technologies, allowing direct comparison of results between studies and leading to a greater understanding of MPs in disease. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

  8. Image analysis driven single-cell analytics for systems microbiology.

    Science.gov (United States)

    Balomenos, Athanasios D; Tsakanikas, Panagiotis; Aspridou, Zafiro; Tampakaki, Anastasia P; Koutsoumanis, Konstantinos P; Manolakos, Elias S

    2017-04-04

    Time-lapse microscopy is an essential tool for capturing and correlating bacterial morphology and gene expression dynamics at single-cell resolution. However state-of-the-art computational methods are limited in terms of the complexity of cell movies that they can analyze and lack of automation. The proposed Bacterial image analysis driven Single Cell Analytics (BaSCA) computational pipeline addresses these limitations thus enabling high throughput systems microbiology. BaSCA can segment and track multiple bacterial colonies and single-cells, as they grow and divide over time (cell segmentation and lineage tree construction) to give rise to dense communities with thousands of interacting cells in the field of view. It combines advanced image processing and machine learning methods to deliver very accurate bacterial cell segmentation and tracking (F-measure over 95%) even when processing images of imperfect quality with several overcrowded colonies in the field of view. In addition, BaSCA extracts on the fly a plethora of single-cell properties, which get organized into a database summarizing the analysis of the cell movie. We present alternative ways to analyze and visually explore the spatiotemporal evolution of single-cell properties in order to understand trends and epigenetic effects across cell generations. The robustness of BaSCA is demonstrated across different imaging modalities and microscopy types. BaSCA can be used to analyze accurately and efficiently cell movies both at a high resolution (single-cell level) and at a large scale (communities with many dense colonies) as needed to shed light on e.g. how bacterial community effects and epigenetic information transfer play a role on important phenomena for human health, such as biofilm formation, persisters' emergence etc. Moreover, it enables studying the role of single-cell stochasticity without losing sight of community effects that may drive it.

  9. New Array Approaches to Explore Single Cells Genomes

    Science.gov (United States)

    Vanneste, Evelyne; Bittman, Lilach; Van der Aa, Niels; Voet, Thierry; Vermeesch, Joris Robert

    2011-01-01

    Microarray analysis enables the genome-wide detection of copy number variations and the investigation of chromosomal instability. Whereas array techniques have been well established for the analysis of unamplified DNA derived from many cells, it has been more challenging to enable the accurate analysis of single cell genomes. In this review, we provide an overview of single cell DNA amplification techniques, the different array approaches, and discuss their potential applications to study human embryos. PMID:22509179

  10. Advanced Ring-Shaped Microelectrode Assay Combined with Small Rectangular Electrode for Quasi-In vivo Measurement of Cell-to-Cell Conductance in Cardiomyocyte Network

    Science.gov (United States)

    Nomura, Fumimasa; Kaneko, Tomoyuki; Hamada, Tomoyo; Hattori, Akihiro; Yasuda, Kenji

    2013-06-01

    To predict the risk of fatal arrhythmia induced by cardiotoxicity in the highly complex human heart system, we have developed a novel quasi-in vivo electrophysiological measurement assay, which combines a ring-shaped human cardiomyocyte network and a set of two electrodes that form a large single ring-shaped electrode for the direct measurement of irregular cell-to-cell conductance occurrence in a cardiomyocyte network, and a small rectangular microelectrode for forced pacing of cardiomyocyte beating and for acquiring the field potential waveforms of cardiomyocytes. The advantages of this assay are as follows. The electrophysiological signals of cardiomyocytes in the ring-shaped network are superimposed directly on a single loop-shaped electrode, in which the information of asynchronous behavior of cell-to-cell conductance are included, without requiring a set of huge numbers of microelectrode arrays, a set of fast data conversion circuits, or a complex analysis in a computer. Another advantage is that the small rectangular electrode can control the position and timing of forced beating in a ring-shaped human induced pluripotent stem cell (hiPS)-derived cardiomyocyte network and can also acquire the field potentials of cardiomyocytes. First, we constructed the human iPS-derived cardiomyocyte ring-shaped network on the set of two electrodes, and acquired the field potential signals of particular cardiomyocytes in the ring-shaped cardiomyocyte network during simultaneous acquisition of the superimposed signals of whole-cardiomyocyte networks representing cell-to-cell conduction. Using the small rectangular electrode, we have also evaluated the response of the cell network to electrical stimulation. The mean and SD of the minimum stimulation voltage required for pacing (VMin) at the small rectangular electrode was 166+/-74 mV, which is the same as the magnitude of amplitude for the pacing using the ring-shaped electrode (179+/-33 mV). The results showed that the

  11. The Organoid Reconstitution Assay (ORA) for the Functional Analysis of Intestinal Stem and Niche Cells.

    Science.gov (United States)

    Schewe, Matthias; Sacchetti, Andrea; Schmitt, Mark; Fodde, Riccardo

    2017-11-20

    The intestinal epithelium is characterized by an extremely rapid turnover rate. In mammals, the entire epithelial lining is renewed within 4 - 5 days. Adult intestinal stem cells reside at the bottom of the crypts of Lieberkühn, are earmarked by expression of the Lgr5 gene, and preserve homeostasis through their characteristic high proliferative rate 1 . Throughout the small intestine, Lgr5 + stem cells are intermingled with specialized secretory cells called Paneth cells. Paneth cells secrete antibacterial compounds (i.e., lysozyme and cryptdins/defensins) and exert a controlling role on the intestinal flora. More recently, a novel function has been discovered for Paneth cells, namely their capacity to provide niche support to Lgr5 + stem cells through several key ligands as Wnt3, EGF, and Dll1 2 . When isolated ex vivo and cultured in the presence of specific growth factors and extracellular matrix components, whole intestinal crypts give rise to long-lived and self-renewing 3D structures called organoids that highly resemble the crypt-villus epithelial architecture of the adult small intestine 3 . Organoid cultures, when established from whole crypts, allow the study of self-renewal and differentiation of the intestinal stem cell niche, though without addressing the contribution of its individual components, namely the Lgr5 + and Paneth cells. Here, we describe a novel approach to the organoid assay that takes advantage of the ability of Paneth and Lgr5 + cells to associate and form organoids when co-cultured. This approach, here referred to as "organoid reconstitution assay" (ORA), allows the genetic and biochemical modification of Paneth or Lgr5 + stem cells, followed by reconstitution into organoids. As such, it allows the functional analysis of the two main components of the intestinal stem cell niche.

  12. Late radiation response of kidney assayed by tubule-cell survival

    International Nuclear Information System (INIS)

    Withers, H.R.; Mason, K.A.

    1986-01-01

    An assay for the survival of renal tubule cells was developed using mice, analogous to other in-situ clonogenic cell survival assays. One kidney was irradiated using a 137 Cs irradiator and removed 60-68 weeks later for histological examination. In unirradiated animals there were about 370 tubules in contact with the capsule in a coronal cross section at the middle of the kidney. After irradiation, extensive tubular damage was the dominant lesion. The number of epithelialised tubules in contact with the capsule showed a dose-dependent logarithmic decline. The dose-survival relationship for the clonogenic cells responsible for the regeneration of tubule epithelium was described by a D 0 value of 1.5 Gy over the dose range 11-16 Gy. This radiosensitivity resembles that of stem cells in acutely responding tissues. The lack of histological evidence of damage to the arterial vasculature at the time the tubules are initially denuded of epithelium, and the similarity of renal tubule cell radiosensitivity to that of other mammalian cells, support the hypothesis that ''late'' radiation injury results primarily from depletion of parenchymal cells, not indirectly from injury to blood vessels, as has been the prevailing belief. (author)

  13. Fundamentals of rapid injection molding for microfluidic cell-based assays.

    Science.gov (United States)

    Lee, Ulri N; Su, Xiaojing; Guckenberger, David J; Dostie, Ashley M; Zhang, Tianzi; Berthier, Erwin; Theberge, Ashleigh B

    2018-01-30

    Microscale cell-based assays have demonstrated unique capabilities in reproducing important cellular behaviors for diagnostics and basic biological research. As these assays move beyond the prototyping stage and into biological and clinical research environments, there is a need to produce microscale culture platforms more rapidly, cost-effectively, and reproducibly. 'Rapid' injection molding is poised to meet this need as it enables some of the benefits of traditional high volume injection molding at a fraction of the cost. However, rapid injection molding has limitations due to the material and methods used for mold fabrication. Here, we characterize advantages and limitations of rapid injection molding for microfluidic device fabrication through measurement of key features for cell culture applications including channel geometry, feature consistency, floor thickness, and surface polishing. We demonstrate phase contrast and fluorescence imaging of cells grown in rapid injection molded devices and provide design recommendations to successfully utilize rapid injection molding methods for microscale cell-based assay development in academic laboratory settings.

  14. Correlation between luminescence intensity and cytotoxicity in cell-based cytotoxicity assay using luciferase.

    Science.gov (United States)

    Wakuri, S; Yamakage, K; Kazuki, Y; Kazuki, K; Oshimura, M; Aburatani, S; Yasunaga, M; Nakajima, Y

    2017-04-01

    The luciferase reporter assay has become one of the conventional methods for cytotoxicity evaluation. Typically, the decrease of luminescence expressed by a constitutive promoter is used as an index of cytotoxicity. However, to our knowledge, there have been no reports of the correlation between cytotoxicity and luminescence intensity. In this study, to accurately verify the correlation between them, beetle luciferase was stably expressed in human hepatoma HepG2 cells harboring the multi-integrase mouse artificial chromosome vector. We showed that the cytotoxicity assay using luciferase does not depend on the stability of luciferase protein and the kind of constitutive promoter. Next, HepG2 cells in which green-emitting beetle luciferase was expressed under the control of CAG promoter were exposed to 58 compounds. The luminescence intensity and cytotoxicity curves of cells exposed to 48 compounds showed similar tendencies, whereas those of cells exposed to 10 compounds did not do so, although the curves gradually approached each other with increasing exposure time. Finally, we demonstrated that luciferase expressed under the control of a constitutive promoter can be utilized both as an internal control reporter for normalizing a test reporter and for monitoring cytotoxicity when two kinds of luciferases are simultaneously used in the cytotoxicity assay. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. On-slide detection of enzymatic activities in selected single cells.

    Science.gov (United States)

    Keller, Josephine Geertsen; Tesauro, Cinzia; Coletta, Andrea; Graversen, Astrid Damgaard; Ho, Yi-Ping; Kristensen, Peter; Stougaard, Magnus; Knudsen, Birgitta Ruth

    2017-09-21

    With increasing recognition of the importance in addressing cell-to-cell heterogeneity for the understanding of complex biological systems, there is a growing need for assays capable of single cell analyses. In the current study, we describe the measurement of human topoisomerase I activity in single CD44 positive Caco2 cells specifically captured from a mixed population on glass slides, which were dual functionalized with anti-CD44-antibodies and specific DNA primers. On-slide lysis of captured CD44 positive cells, resulted in the release of human topoisomerase I, allowing the enzyme to circularize a specific linear DNA substrate added to the slides. The generated circles hybridized to the anchored DNA primers and acted as templates for a solid support rolling circle amplification reaction leading to the generation of long tandem repeat products that were detected at the single molecule level in a fluorescent microscope upon hybridization of fluorescent labelled probes. The on-slide detection system was demonstrated to be directly quantitative and specific towards CD44 positive cells. Moreover, it allowed reproducible detection of human topoisomerase I activity in single cells.

  16. Combining intracellular and secreted bioluminescent reporter proteins for multicolor cell-based assays.

    Science.gov (United States)

    Michelini, Elisa; Cevenini, Luca; Mezzanotte, Laura; Ablamsky, Danielle; Southworth, Tara; Branchini, Bruce R; Roda, Aldo

    2008-02-01

    Bioluminescent (BL) proteins are a promising tool for diverse applications based on reporter gene technology thanks to their high sensitivity and range of linear response. Due to their widespread use in the environmental, medical and agro-food fields, there is a great need for new BL reporter proteins with improved characteristics to provide researches a wide range of suitable reporters. Few efforts have been made in this direction and further improvement of BL reporter features (e.g., thermostability, narrower emission bandwidth, emission at different wavelengths) tailored for specific applications would be a remarkable progress toward the development of ultrasensitive multiplexed assays either in vitro or in vivo. The suitability of using red- and green-emitting thermostable mutants of Photinus pyralis firefly luciferase and two click beetle luciferases in combination with a secreted luciferase from Gaussia princeps was evaluated to develop a triple-color mammalian assay. Two triple-reporter model mammalian systems were developed in a human hepatoblastoma cell line to monitor the transcriptional regulation of cholesterol 7-alpha hydroxylase (cyp7a1), the enzyme that catalyzes the first and rate-limiting step of the main pathway responsible for cholesterol degradation in humans. These model systems allowed us to evaluate the feasibility of using two intracellular BL reporters and a secreted one in the same cell-based assay. The selection of reporter proteins characterized by similar expression levels was identified as a critical point for the development of a multicolor assay.

  17. Analysis of close associations of uropod-associated proteins in human T-cells using the proximity ligation assay

    Directory of Open Access Journals (Sweden)

    Tommy Baumann

    2013-10-01

    Full Text Available We have shown previously that the raft-associated proteins flotillin-1 and -2 are rapidly recruited to the uropods of chemoattractant-stimulated human neutrophils and T-cells and are involved in cell polarization. Other proteins such as the adhesion receptor PSGL-1, the actin-membrane linker proteins ezrin/radixin/moesin (ERM and the signaling enzyme phosphatidylinositol-4-phosphate 5-kinase type Iγ90 (PIPKIγ90 also accumulate in the T-cell uropod. Using the in situ proximity ligation assay (PLA we now have investigated putative close associations of these proteins in human freshly isolated T-cells before and after chemokine addition. The PLA allows in situ subcellular localization of close proximity of endogenous proteins at single-molecule resolution in fixed cells. It allows detection also of weaker and transient complexes that would not be revealed with co-immunoprecipitation approaches. We previously provided evidence for heterodimer formation of tagged flotillin-1 and -2 in T-cells before and after chemokine addition using fluorescence resonance energy transfer (FRET. We now confirm these findings using PLA for the endogenous flotillins in fixed human T-cells. Moreover, in agreement with the literature, our PLA findings confirm a close association of endogenous PSGL-1 and ERM proteins both in resting and chemokine-activated human T-cells. In addition, we provide novel evidence using the PLA for close associations of endogenous activated ERM proteins with PIPKIγ90 and of endogenous flotillins with PSGL-1 in human T-cells, before and after chemokine addition. Our findings suggest that preformed clusters of these proteins coalesce in the uropod upon cell stimulation.

  18. Gene-targeted embryonic stem cells: real-time PCR assay for estimation of the number of neomycin selection cassettes

    Directory of Open Access Journals (Sweden)

    Mancini Cecilia

    2011-10-01

    Full Text Available Abstract In the preparation of transgenic murine ES cells it is important to verify the construct has a single insertion, because an ectopic neomycin phosphortransferase positive selection cassette (NEO may cause a position effect. During a recent work, where a knockin SCA28 mouse was prepared, we developed two assays based on Real-Time PCR using both SYBR Green and specific minor groove binder (MGB probes to evaluate the copies of NEO using the comparative delta-delta Ct method versus the Rpp30 reference gene. We compared the results from Southern blot, routinely used to quantify NEO copies, with the two Real-Time PCR assays. Twenty-two clones containing the single NEO copy showed values of 0.98 ± 0.24 (mean ± 2 S.D., and were clearly distinguishable from clones with two or more NEO copies. This method was found to be useful, easy, sensitive and fast and could substitute for the widely used, but laborious Southern blot method.

  19. Multimodal sensory integration in single cerebellar granule cells in vivo.

    Science.gov (United States)

    Ishikawa, Taro; Shimuta, Misa; Häusser, Michael

    2015-12-29

    The mammalian cerebellum is a highly multimodal structure, receiving inputs from multiple sensory modalities and integrating them during complex sensorimotor coordination tasks. Previously, using cell-type-specific anatomical projection mapping, it was shown that multimodal pathways converge onto individual cerebellar granule cells (Huang et al., 2013). Here we directly measure synaptic currents using in vivo patch-clamp recordings and confirm that a subset of single granule cells receive convergent functional multimodal (somatosensory, auditory, and visual) inputs via separate mossy fibers. Furthermore, we show that the integration of multimodal signals by granule cells can enhance action potential output. These recordings directly demonstrate functional convergence of multimodal signals onto single granule cells.

  20. Mass spectrometry-based metabolomics of single yeast cells.

    Science.gov (United States)

    Ibáñez, Alfredo J; Fagerer, Stephan R; Schmidt, Anna Mareike; Urban, Pawel L; Jefimovs, Konstantins; Geiger, Philipp; Dechant, Reinhard; Heinemann, Matthias; Zenobi, Renato

    2013-05-28

    Single-cell level measurements are necessary to characterize the intrinsic biological variability in a population of cells. In this study, we demonstrate that, with the microarrays for mass spectrometry platform, we are able to observe this variability. We monitor environmentally (2-deoxy-D-glucose) and genetically (ΔPFK2) perturbed Saccharomyces cerevisiae cells at the single-cell, few-cell, and population levels. Correlation plots between metabolites from the glycolytic pathway, as well as with the observed ATP/ADP ratio as a measure of cellular energy charge, give biological insight that is not accessible from population-level metabolomic data.

  1. Bioinformatics approaches to single-cell analysis in developmental biology.

    Science.gov (United States)

    Yalcin, Dicle; Hakguder, Zeynep M; Otu, Hasan H

    2016-03-01

    Individual cells within the same population show various degrees of heterogeneity, which may be better handled with single-cell analysis to address biological and clinical questions. Single-cell analysis is especially important in developmental biology as subtle spatial and temporal differences in cells have significant associations with cell fate decisions during differentiation and with the description of a particular state of a cell exhibiting an aberrant phenotype. Biotechnological advances, especially in the area of microfluidics, have led to a robust, massively parallel and multi-dimensional capturing, sorting, and lysis of single-cells and amplification of related macromolecules, which have enabled the use of imaging and omics techniques on single cells. There have been improvements in computational single-cell image analysis in developmental biology regarding feature extraction, segmentation, image enhancement and machine learning, handling limitations of optical resolution to gain new perspectives from the raw microscopy images. Omics approaches, such as transcriptomics, genomics and epigenomics, targeting gene and small RNA expression, single nucleotide and structural variations and methylation and histone modifications, rely heavily on high-throughput sequencing technologies. Although there are well-established bioinformatics methods for analysis of sequence data, there are limited bioinformatics approaches which address experimental design, sample size considerations, amplification bias, normalization, differential expression, coverage, clustering and classification issues, specifically applied at the single-cell level. In this review, we summarize biological and technological advancements, discuss challenges faced in the aforementioned data acquisition and analysis issues and present future prospects for application of single-cell analyses to developmental biology. © The Author 2015. Published by Oxford University Press on behalf of the European

  2. Serum-free freezing media support high cell quality and excellent ELISPOT assay performance across a wide variety of different assay protocols.

    Science.gov (United States)

    Filbert, Helene; Attig, Sebastian; Bidmon, Nicole; Renard, Bernhard Y; Janetzki, Sylvia; Sahin, Ugur; Welters, Marij J P; Ottensmeier, Christian; van der Burg, Sjoerd H; Gouttefangeas, Cécile; Britten, Cedrik M

    2013-04-01

    Robust and sensitive ELISPOT protocols are commonly applied concomitant with the development of new immunotherapeutics. Despite the knowledge that individual serum batches differ in their composition and may change properties over time, serum is still commonly used in immunologic assays. Commercially available serum batches are expensive, limited in quantity and need to be pretested for suitability in immunologic assays, which is a laborious process. The aim of this study was to test whether serum-free freezing media can lead to high cell viability and favorable performance across multiple ELISPOT assay protocols. Thirty-one laboratories from ten countries participated in a proficiency panel organized by the Cancer Immunotherapy Immunoguiding Program to test the influence of different freezing media on cell quality and immunologic function. Each center received peripheral blood mononuclear cells which were frozen in three different media. The participants were asked to quantify antigen-specific CD8+ T-cell responses against model antigens using their locally established IFN-gamma ELISPOT protocols. Self-made and commercially available serum-free freezing media led to higher cell viability and similar cell recovery after thawing and resting compared to freezing media supplemented with human serum. Furthermore, the test performance as determined by (1) background spot production, (2) replicate variation, (3) frequency of detected antigen-specific spots and (4) response detection rate was similar for serum and serum-free conditions. We conclude that defined and accessible serum-free freezing media should be recommended for freezing cells stored for subsequent ELISPOT analysis.

  3. Single-cell Analysis of Lambda Immunity Regulation

    DEFF Research Database (Denmark)

    Bæk, Kristoffer Torbjørn; Svenningsen, Sine Lo; Eisen, Harvey

    2003-01-01

    We have examined expression of the ¿cI operon in single cells via a rexgfp substitution. Although average fluorescence agreed with expectations for expression of ¿-repressor, fluorescence fluctuated greatly from cell-to-cell. Fluctuations in repressor concentration are not predicted by previous m...

  4. Dielectrophoretic capture and genetic analysis of single neuroblastoma tumor cells

    Directory of Open Access Journals (Sweden)

    Erica L Carpenter

    2014-07-01

    Full Text Available Our understanding of the diversity of cells that escape the primary tumor and seed micrometastases remains rudimentary, and approaches for studying circulating and disseminated tumor cells have been limited by low throughput and sensitivity, reliance on single parameter sorting, and a focus on enumeration rather than phenotypic and genetic characterization. Here we utilize a highly sensitive microfluidic and dielectrophoretic approach for the isolation and genetic analysis of individual tumor cells. We employed fluorescence labeling to isolate 208 single cells from spiking experiments conducted with 11 cell lines, including 8 neuroblastoma cell lines, and achieved a capture sensitivity of 1 tumor cell per 106 white blood cells. Sample fixation or freezing had no detectable effect on cell capture. Point mutations were accurately detected in the whole genome amplification product of captured single tumor cells but not in negative control white blood cells. We applied this approach to capture 144 single tumor cells from 10 bone marrow samples from patients suffering from neuroblastoma. In this pediatric malignancy, high-risk patients often exhibit wide-spread hematogenous metastasis, but access to primary tumor can be difficult or impossible. Here we used flow-based sorting to pre-enrich samples with tumor involvement below 0.02%. For all patients for whom a mutation in the Anaplastic Lymphoma Kinase gene had already been detected in their primary tumor, the same mutation was detected in single cells from their marrow. These findings demonstrate a novel, non-invasive, and adaptable method for the capture and genetic analysis of single tumor cells from cancer patients.

  5. Reconstructing Cell Lineages from Single-Cell Gene Expression Data: A Pilot Study

    Science.gov (United States)

    2016-08-30

    Reconstructing cell lineages from single -cell gene expression data: a pilot study The goal of this pilot study is to develop novel mathematical...methods, by leveraging tools developed in the bifurcation theory, to infer the underlying cell-state dynamics from single -cell gene expression data. Our...from single -cell gene expression data. The views, opinions and/or findings contained in this report are those of the author(s) and should not contrued

  6. Single-Cell Expression Profiling and Proteomics of Primordial Germ Cells, Spermatogonial Stem Cells, Adult Germ Stem Cells, and Oocytes.

    Science.gov (United States)

    Conrad, Sabine; Azizi, Hossein; Skutella, Thomas

    2018-01-04

    The mammalian germ cells, cell assemblies, tissues, and organs during development and maturation have been extensively studied at the tissue level. However, to investigate and understand the fundamental insights at the molecular basis of germ and stem cells, their cell fate plasticity, and determination, it is of most importance to analyze at the large scale on the single-cell level through different biological windows. Here, modern molecular techniques optimized for single-cell analysis, including single fluorescence-activated cell sorting (FACS) and single-cell RNA sequencing (scRNA-seq) or microfluidic high-throughput quantitative real-time polymerase chain reaction (qRT-PCR) for single-cell gene expression and liquid chromatography coupled to tandem mass spectrometry (LC-MSMS) for protein profiling, have been established and are still getting optimized.This review aims on describing and discussing recent single-cell expression profiling and proteomics of different types of human germ cells, including primordial germ cells (PGCs), spermatogonial stem cells (SSCs), human adult germ stem cells (haGSCs), and oocytes.

  7. Genomic Sequencing of Single Microbial Cells from Environmental Samples

    Energy Technology Data Exchange (ETDEWEB)

    Ishoey, Thomas; Woyke, Tanja; Stepanauskas, Ramunas; Novotny, Mark; Lasken, Roger S.

    2008-02-01

    Recently developed techniques allow genomic DNA sequencing from single microbial cells [Lasken RS: Single-cell genomic sequencing using multiple displacement amplification, Curr Opin Microbiol 2007, 10:510-516]. Here, we focus on research strategies for putting these methods into practice in the laboratory setting. An immediate consequence of single-cell sequencing is that it provides an alternative to culturing organisms as a prerequisite for genomic sequencing. The microgram amounts of DNA required as template are amplified from a single bacterium by a method called multiple displacement amplification (MDA) avoiding the need to grow cells. The ability to sequence DNA from individual cells will likely have an immense impact on microbiology considering the vast numbers of novel organisms, which have been inaccessible unless culture-independent methods could be used. However, special approaches have been necessary to work with amplified DNA. MDA may not recover the entire genome from the single copy present in most bacteria. Also, some sequence rearrangements can occur during the DNA amplification reaction. Over the past two years many research groups have begun to use MDA, and some practical approaches to single-cell sequencing have been developed. We review the consensus that is emerging on optimum methods, reliability of amplified template, and the proper interpretation of 'composite' genomes which result from the necessity of combining data from several single-cell MDA reactions in order to complete the assembly. Preferred laboratory methods are considered on the basis of experience at several large sequencing centers where >70% of genomes are now often recovered from single cells. Methods are reviewed for preparation of bacterial fractions from environmental samples, single-cell isolation, DNA amplification by MDA, and DNA sequencing.

  8. Aloe vera is non-toxic to cells: A microculture tetrazolium technique colorimetric assay study

    Directory of Open Access Journals (Sweden)

    Devi Gopakumar

    2014-01-01

    Full Text Available Introduction: Aloe vera (Av, a succulent of Liliaceae family is now a widely used medicinal plant. Its′ application covers a wide spectrum of human diseases, including oral mucosa, gastric mucosa and skin. Aloe vera preparations in the form of gel, mouth washes and cream are applied topically for many oral diseases. The applications include oral lichen planus, candidiasis, oral submucous fibrosis, geographic tongue, etc. Aims and Objectives: To evaluate the cytotoxicity of Av on human fibroblasts. Materials and Methods: Aloe vera preparation (70% was applied on the fibroblast cell lineage and the cell viability was evaluated by microculture tetrazolium technique (MTT colorimetric assay. Results: The cell viability at different concentrations was measured. The cells have maintained their viability at different concentrations used in the study. Conclusion: Our study shows the cell viability at different sample concentrations of Av. This could open up wide clinical applications of Av for reactive, inflammatory and potentially malignant oral and other mucocutaneous diseases.

  9. Effects of several salt marsh plants on mouse spleen and thymus cell proliferation using mtt assay

    Science.gov (United States)

    Seo, Youngwan; Lee, Hee-Jung; Kim, You Ah; Youn, Hyun Joo; Lee, Burm-Jong

    2005-12-01

    In the present study, we have tested the effects of 21 salt marsh plants on cell proliferation of mouse immune cells (spleen and thymus) using MTT assay in culture. The methanolic extracts of six salt marsh plants ( Rosa rugosa, Ixeris tamagawaensis, Artemisia capillaris, Tetragonia tetragonoides, Erigeron annus, and Glehnia littoralis) showed very powerful suppressive effects of mouse immune cell death and significant activities of cell proliferation in vitro. Especially, the methanolic extract of Rosa rugosa was found to have fifteen times compared to the control treatment, demonstrating that Rosa rugosa may have a potent stimulation effect on immune cell proliferation. These results suggest that several salt marsh plants including Rosa rugosa could be useful for further study as an immunomodulating agent.

  10. Development and characterization of a Rift Valley fever virus cell-cell fusion assay using alphavirus replicon vectors

    International Nuclear Information System (INIS)

    Filone, Claire Marie; Heise, Mark; Doms, Robert W.; Bertolotti-Ciarlet, Andrea

    2006-01-01

    Rift Valley fever virus (RVFV), a member of the Phlebovirus genus in the Bunyaviridae family, is transmitted by mosquitoes and infects both humans and domestic animals, particularly cattle and sheep. Since primary RVFV strains must be handled in BSL-3+ or BSL-4 facilities, a RVFV cell-cell fusion assay will facilitate the investigation of RVFV glycoprotein function under BSL-2 conditions. As for other members of the Bunyaviridae family, RVFV glycoproteins are targeted to the Golgi, where the virus buds, and are not efficiently delivered to the cell surface. However, overexpression of RVFV glycoproteins using an alphavirus replicon vector resulted in the expression of the glycoproteins on the surface of multiple cell types. Brief treatment of RVFV glycoprotein expressing cells with mildly acidic media (pH 6.2 and below) resulted in rapid and efficient syncytia formation, which we quantified by β-galactosidase α-complementation. Fusion was observed with several cell types, suggesting that the receptor(s) for RVFV is widely expressed or that this acid-dependent virus does not require a specific receptor to mediate cell-cell fusion. Fusion occurred over a broad temperature range, as expected for a virus with both mosquito and mammalian hosts. In contrast to cell fusion mediated by the VSV-G glycoprotein, RVFV glycoprotein-dependent cell fusion could be prevented by treating target cells with trypsin, indicating that one or more proteins (or protein-associated carbohydrate) on the host cell surface are needed to support membrane fusion. The cell-cell fusion assay reported here will make it possible to study the membrane fusion activity of RVFV glycoproteins in a high-throughput format and to screen small molecule inhibitors for the ability to block virus-specific membrane fusion

  11. Single-cell phospho-protein analysis by flow cytometry.

    Science.gov (United States)

    Schulz, Kenneth R; Danna, Erika A; Krutzik, Peter O; Nolan, Garry P

    2012-02-01

    This protocol describes methods for monitoring intracellular phosphorylation-dependent signaling events on a single-cell basis. This approach measures cell signaling by treating cells with exogenous stimuli, fixing cells with formaldehyde, permeabilizing with methanol, and then staining with phospho-specific antibodies. Thus, cell signaling states can be determined as a measure of how cells interact with their environment. This method has applications in clinical research as well as mechanistic studies of basic biology. In clinical research, diagnostic or drug efficacy information can be retrieved by discovering how a disease affects the ability of cells to respond to growth factors. Basic scientists can use this technique to analyze signaling events in cell lines and human or murine primary cells, including rare populations, like B1 cells or stem cells. This technique has broad applications bringing standard biochemical analysis into primary cells in order to garner valuable information about signaling events in physiologic settings. © 2012 by John Wiley & Sons, Inc.

  12. Absorption characteristics of the total alkaloids from Mahonia bealei in an in situ single-pass intestinal perfusion assay.

    Science.gov (United States)

    Sun, Yu-He; He, Xin; Yang, Xiao-Lin; Dong, Cui-Lan; Zhang, Chun-Feng; Song, Zi-Jing; Lu, Ming-Xing; Yang, Zhong-Lin; Li, Ping

    2014-07-01

    To investigate the absorption characteristics of the total alkaloids from Mahoniae Caulis (TAMC) through the administration of monterpene absorption enhancers or protein inhibitors. The absorption behavior was investigated in an in situ single-pass intestinal perfusion (SPIP) assay in rats. The intestinal absorption of TAMC was much more than that of a single compound or a mixture of compounds (jatrorrhizine, palmatine, and berberine). Promotion of absorption by the bicyclic monoterpenoids (borneol or camphor) was higher than by the monocyclic monoterpenes (menthol or menthone), and promotion by compounds with a hydroxyl group (borneol or menthol) was higher than those with a carbonyl group (camphor or menthone). The apparent permeability coefficient (Papp) of TAMC was increased to 1.8-fold by verapamil, while it was reduced to one half by thiamine. The absorption rate constant (Ka) and Papp of TAMC were unchanged by probenecid and pantoprazole. The intestinal absorption characteristics of TAMC might be passive transport, and the intestinum tenue was the best absorptive site. In addition, TAMC might be likely a substrate of P-glycoprotein (P-gp) and organic cation transporters (OCT), rather than multidrug resistance protein (MRP) and breast cancer resistance protein (BCRP). Compared with a single compound and a mixture of compounds, TAMC was able to be absorbed in the blood circulation effectively. Copyright © 2014 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

  13. Novel Real-Time Proximity Assay for Characterizing Multiple Receptor Interactions on Living Cells.

    Science.gov (United States)

    Bondza, Sina; Björkelund, Hanna; Nestor, Marika; Andersson, Karl; Buijs, Jos

    2017-12-19

    Cellular receptor activity is often controlled through complex mechanisms involving interactions with multiple molecules, which can be soluble ligands and/or other cell surface molecules. In this study, we combine a fluorescence-based technology for real-time interaction analysis with fluorescence quenching to create a novel time-resolved proximity assay to study protein-receptor interactions on living cells. This assay extracts the binding kinetics and affinity for two proteins if they bind in proximity on the cell surface. One application of real-time proximity interaction analysis is to study relative levels of receptor dimerization. The method was primarily evaluated using the HER2 binding antibodies Trastuzumab and Pertuzumab and two EGFR binding antibodies including Cetuximab. Using Cetuximab and Trastuzumab, proximity of EGFR and HER2 was investigated before and after treatment of cells with the tyrosine-kinase inhibitor Gefitinib. Treated cells displayed 50% increased proximity signal, whereas the binding characteristics of the two antibodies were not significantly affected, implying an increase in the EGFR-HER2 dimer level. These results demonstrate that real-time proximity interaction analysis enables determination of the interaction rate constants and affinity of two ligands while simultaneously quantifying their relative colocalization on living cells.

  14. Identifying tumor cell growth inhibitors by combinatorial chemistry and zebrafish assays.

    Directory of Open Access Journals (Sweden)

    Jing Xiang

    Full Text Available Cyclin-dependent kinases (CDKs play important roles in regulating cell cycle progression, and altered cell cycles resulting from over-expression or abnormal activation of CDKs observed in many human cancers. As a result, CDKs have become extensive studied targets for developing chemical inhibitors for cancer therapies; however, protein kinases share a highly conserved ATP binding pocket at which most chemical inhibitors bind, therefore, a major challenge in developing kinase inhibitors is achieving target selectivity. To identify cell growth inhibitors with potential applications in cancer therapy, we used an integrated approach that combines one-pot chemical synthesis in a combinatorial manner to generate diversified small molecules with new chemical scaffolds coupled with growth inhibition assay using developing zebrafish embryos. We report the successful identification of a novel lead compound that displays selective inhibitory effects on CDK2 activity, cancer cell proliferation, and tumor progression in vivo. Our approaches should have general applications in developing cell proliferation inhibitors using an efficient combinatorial chemical genetic method and integrated biological assays. The novel cell growth inhibitor we identified should have potential as a cancer therapeutic agent.

  15. Cytotoxic Effect of Iron Oxide Nanoparticles on Mouse Embryonic Stem Cells by MTT Assay

    Directory of Open Access Journals (Sweden)

    Homa Mohseni Kouchesfehani

    2016-07-01

    Full Text Available Background: Despite the wide range of applications, there is a serious lack of information on the impact of the nanoparticles on human health and the environment. The present study was done to determine the range of dangerous concentrations of iron oxide nanoparticle and their effects on mouse embryonic stem cells. Methods: Iron oxide nanoparticles with less than 20 nanometers diameter were encapsulated by a PEG-phospholipid. The suspension of iron oxide nanoparticles was prepared using the culture media and cell viability was determined by MTT assay. Results: MTT assay was used to examine the cytotoxicity of iron oxide nanoparticle s. Royan B1 cells were treated with medium containing different concentrations (10, 20, 30, 40, 50, and 60µg/ml of the iron oxide nanoparticle. Cell viability was determined at 12 and 24 hours after treatment which showed significant decreases when concentration and time period increased. Conclusion: The main mechanism of nanoparticles action is still unknown, but in vivo and in vitro studies in different environments suggest that they are capable of producing reactive oxygen species (ROS. Therefore, they may have an effect on the concentration of intracellular calcium, activation of transcription factors, and changes in cytokine. The results of this study show that the higher concentration and duration of treatment of cells with iron oxide nanoparticles increase the rate of cell death.

  16. CYTOKINESIS-BLOCK MICRONUCLEUS ASSAY IN HUMAN GLIOMA CELLS EXPOSED TO RADIATION

    Directory of Open Access Journals (Sweden)

    Jerzy Slowinski

    2011-05-01

    Full Text Available Biological tests are efficient in reflecting the biological influences of several types of generally harmful exposures. The micronucleus assay is widely used in genotoxicity studies or studies on genomic damage in general. We present methodological aspects of cytokinesis-block micronucleus assay performed in human gliomas irradiated in vitro. Eight human glioblastoma cell lines obtained from DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Germany were gamma-irradiated (60Co over a dose range of 0-10 Gy. Cytokinesis-block micronucleus assay was performed to quantitate cytogenetic damage. The cells were fixed directly on dishes, stained with fluorochrome DAPI and evaluated under fluorescent and phase contrast microscope. The micronucleus frequency was expressed as a micronuclei (MN per binucleated cell (BNC ratio, calculated after scoring at least 100 BNC per dish. The frequency of spontaneous MN ranged from 0.17 to 0.613 (mean: 0.29 ± 0.14. After irradiation increase of MN frequency in the range of 0.312 - 2.241 (mean: 0.98 ± 0.68 was found at 10 Gy. Gliomas are extremely heterogenous in regard to cytogenetic effects of irradiation, as shown in this study by cytokinesis-block micronucleus assay. This test is easily performed on irradiated glioma cell lines and can assist in determining their radiosensitivity. However, in order to obtain reliable and reproducible results, precise criteria for MN scoring must be strictly followed. Simultaneous use of fluorescent and phase contrast equipment improves imaging of morphological details and can further optimize MN scoring.

  17. Gamma-ray imaging and holdup assays of 235-F PuFF cells 1 & 2

    Energy Technology Data Exchange (ETDEWEB)

    Aucott, T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-12-20

    Savannah River National Laboratory (SRNL) Nuclear Measurements (L4120) was tasked with performing enhanced characterization of the holdup in the PuFF shielded cells. Assays were performed in accordance with L16.1-ADS-2460 using two high-resolution gamma-ray detectors. The first detector, an In Situ Object Counting System (ISOCS)-characterized detector, was used in conjunction with the ISOCS Geometry Composer software to quantify grams of holdup. The second detector, a Germanium Gamma-ray Imager (GeGI), was used to visualize the location and relative intensity of the holdup in the cells. Carts and collimators were specially designed to perform optimum assays of the cells. Thick, pencil-beam tungsten collimators were fabricated to allow for extremely precise targeting of items of interest inside the cells. Carts were designed with a wide range of motion to position and align the detectors. A total of 24 measurements were made, each typically 24 hours or longer to provide sufficient statistical precision. This report presents the results of the enhanced characterization for cells 1 and 2. The measured gram values agree very well with results from the 2014 study. In addition, images were created using both the 2014 data and the new GeGI data. The GeGI images of the cells walls reveal significant Pu-238 holdup on the surface of the walls in cells 1 and 2. Additionally, holdup is visible in the two pass-throughs from cell 1 to the wing cabinets. This report documents the final element (exterior measurements coupled with gamma-ray imaging and modeling) of the enhanced characterization of cells 1-5 (East Cell Line).

  18. UPregulated single-stranded DNA-binding protein 1 induces cell chemoresistance to cisplatin in lung cancer cell lines.

    Science.gov (United States)

    Zhao, Xiang; He, Rong; Liu, Yu; Wu, Yongkai; Kang, Leitao

    2017-07-01

    Cisplatin and its analogues are widely used as anti-tumor drugs in lung cancer but many cisplatin-resistant lung cancer cases have been identified in recent years. Single-stranded DNA-binding protein 1 (SSDBP1) can effectively induce H69 cell resistance to cisplatin in our previous identification; thus, it is necessary to explore the mechanism underlying the effects of SSDBP1-induced resistance to cisplatin. First, SSDBP1-overexpressed or silent cell line was constructed and used to analyze the effects of SSDBP1 on chemoresistance of lung cancer cells to cisplatin. SSDBP1 expression was assayed by real-time PCR and Western blot. Next, the effects of SSDBP1 on cisplatin sensitivity, proliferation, and apoptosis of lung cancer cell lines were assayed by MTT and flow cytometry, respectively; ABC transporters, apoptosis-related genes, and cell cycle-related genes by real-time PCR, and DNA wound repair by comet assay. Low expression of SSDBP1 was observed in H69 cells, while increased expression in cisplatin-resistant H69 cells. Upregulated expression of SSDBP1 in H69AR cells was identified to promote proliferation and cisplatin resistance and inhibit apoptosis, while downregulation of SSDBP1 to inhibit cisplatin resistance and proliferation and promoted apoptosis. Moreover, SSDBP1 promoted the expression of P2gp, MRP1, Cyclin D1, and CDK4 and inhibited the expression of caspase 3 and caspase 9. Furthermore, SSDBP1 promoted the DNA wound repair. These results indicated that SSDBP1 may induce cell chemoresistance of cisplatin through promoting DNA repair, resistance-related gene expression, cell proliferation, and inhibiting apoptosis.

  19. A quantitative evaluation of cell migration by the phagokinetic track motility assay.

    Science.gov (United States)

    Nogalski, Maciej T; Chan, Gary C T; Stevenson, Emily V; Collins-McMillen, Donna K; Yurochko, Andrew D

    2012-12-04

    Cellular motility is an important biological process for both unicellular and multicellular organisms. It is essential for movement of unicellular organisms towards a source of nutrients or away from unsuitable conditions, as well as in multicellular organisms for tissue development, immune surveillance and wound healing, just to mention a few roles(1,2,3). Deregulation of this process can lead to serious neurological, cardiovascular and immunological diseases, as well as exacerbated tumor formation and spread(4,5). Molecularly, actin polymerization and receptor recycling have been shown to play important roles in creating cellular extensions (lamellipodia), that drive the forward movement of the cell(6,7,8). However, many biological questions about cell migration remain unanswered. The central role for cellular motility in human health and disease underlines the importance of understanding the specific mechanisms involved in this process and makes accurate methods for evaluating cell motility particularly important. Microscopes are usually used to visualize the movement of cells. However, cells move rather slowly, making the quantitative measurement of cell migration a resource-consuming process requiring expensive cameras and software to create quantitative time-lapsed movies of motile cells. Therefore, the ability to perform a quantitative measurement of cell migration that is cost-effective, non-laborious, and that utilizes common laboratory equipment is a great need for many researchers. The phagokinetic track motility assay utilizes the ability of a moving cell to clear gold particles from its path to create a measurable track on a colloidal gold-coated glass coverslip(9,10). With the use of freely available software, multiple tracks can be evaluated for each treatment to accomplish statistical requirements. The assay can be utilized to assess motility of many cell types, such as cancer cells(11,12), fibroblasts(9), neutrophils(13), skeletal muscle cells(14

  20. Platforms for Single-Cell Collection and Analysis

    Directory of Open Access Journals (Sweden)

    Lukas Valihrach

    2018-03-01

    Full Text Available Single-cell analysis has become an established method to study cell heterogeneity and for rare cell characterization. Despite the high cost and technical constraints, applications are increasing every year in all fields of biology. Following the trend, there is a tremendous development of tools for single-cell analysis, especially in the RNA sequencing field. Every improvement increases sensitivity and throughput. Collecting a large amount of data also stimulates the development of new approaches for bioinformatic analysis and interpretation. However, the essential requirement for any analysis is the collection of single cells of high quality. The single-cell isolation must be fast, effective, and gentle to maintain the native expression profiles. Classical methods for single-cell isolation are micromanipulation, microdissection, and fluorescence-activated cell sorting (FACS. In the last decade several new and highly efficient approaches have been developed, which not just supplement but may fully replace the traditional ones. These new techniques are based on microfluidic chips, droplets, micro-well plates, and automatic collection of cells using capillaries, magnets, an electric field, or a punching probe. In this review we summarize the current methods and developments in this field. We discuss the advantages of the different commercially available platforms and their applicability, and also provide remarks on future developments.

  1. Development of a recombinant DNA assay system for the detection of genetic change in astronauts' cells

    International Nuclear Information System (INIS)

    Atchley, S.V.; Chen, D.J.C.; Strniste, G.F.; Walters, R.A.; Moyzis, R.K.

    1984-01-01

    We are developing a new recombinant DNA system for the detection and measurement of genetic change in humans caused by exposure to low level ionizing radiation. A unique feature of the method is the use of cloned repetitive DNA probes to assay human DNA for structural changes during or after irradiation. Repetitive sequences exist in different families. Collectively they constitute over 25% of the DNA in a human cell. Repeat families have between 10 and 500,000 members. We have constructed repetitive DNA sequence libraries using recombinant DNA techniques. From these libraries we have isolated and characterized individual repeats comprising 75 to 90% of the mass of human repetitive DNA. Repeats used in our assay system exist in tandem arrays in the genome. Perturbation of these sequences in a cell, followed by detection with a repeat probe, produces a new, multimeric ''ladder'' pattern on an autoradiogram. The repeat probe used in our initial study is complementary to 1% of human DNA. Therefore, the sensitivity of this method is several orders of magnitude better than existing assays. Preliminary evidence from human skin cells exposed to acute, low-dose x-ray treatments indicates that DNA is affected at a dose as low as 5R. The radiation doses used in this system are well within the range of doses received by astronauts during spaceflight missions. Due to its small material requirements, this technique could easily be adapted for use in space. 16 refs., 1 fig

  2. A high performance liquid chromatographic assay of mefloquine in saliva after a single oral dose in healthy adult Africans.

    Science.gov (United States)

    Gbotosho, Grace O; Happi, Christian T; Lawal, Omowunmi; Sijuade, Abayomi; Sowunmi, Akin; Oduola, Ayoade

    2012-02-27

    Mefloquine-artesunate is a formulation of artemisinin based combination therapy (ACT) recommended by the World Health Organization and historically the first ACT used clinically. The use of ACT demands constant monitoring of therapeutic efficacies and drug levels, in order to ensure that optimum drug exposure is achieved and detect reduced susceptibility to these drugs. Quantification of anti-malarial drugs in biological fluids other than blood would provide a more readily applicable method of therapeutic drug monitoring in developing endemic countries. Efforts in this study were devoted to the development of a simple, field applicable, non-invasive method for assay of mefloquine in saliva. A high performance liquid chromatographic method with UV detection at 220 nm for assaying mefloquine in saliva was developed and validated by comparing mefloquine concentrations in saliva and plasma samples from four healthy volunteers who received single oral dose of mefloquine. Verapamil was used as internal standard. Chromatographic separation was achieved using a Hypersil ODS column. Extraction recoveries of mefloquine in plasma or saliva were 76-86% or 83-93% respectively. Limit of quantification of mefloquine was 20 ng/ml. Agreement between salivary and plasma mefloquine concentrations was satisfactory (r = 0.88, p mefloquine in saliva paralleled that in plasma, making salivary quantification of mefloquine potentially useful in therapeutic drug monitoring. © 2012 Gbotosho et al; licensee BioMed Central Ltd.

  3. Single mutation in the matrix gene of seasonal influenza A viruses critically affects the performance of diagnostic molecular assay.

    Science.gov (United States)

    Duh, Darja; Blažič, Barbara

    2018-01-01

    Reduced intensity of the fluorescence signal in the amplification curve was observed when using a WHO recommended real time RT-PCR for influenza virus detection. A single mutation, G189T, in the conserved region of influenza virus matrix gene was detected by Sanger sequencing. The mutation is located in the probe binding region, hence we speculated it could be the reason for the atypical shape of amplification curve. The mutation was first noted in Slovenia in 2011 and 2013 for seasonal influenza A virus types A(H1N1)pdm09 and A(H3N2), respectively. In the following years, 2014 and 2015, the majority of influenza A(H3N2) viruses alone carried the mutation. The amplification of matrix gene for these influenza A(H3N2) viruses continuously resulted in the atypically shaped amplification curves. The performance of the particular assay was critically affected; therefore, the assay was no longer usable as diagnostic tool for influenza virus detection. Mutations in the conserved region of influenza virus genome are more common than expected and this would need to be considered when targeting matrix gene. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. A high performance liquid chromatographic assay of Mefloquine in saliva after a single oral dose in healthy adult Africans

    Directory of Open Access Journals (Sweden)

    Gbotosho Grace O

    2012-02-01

    Full Text Available Abstract Background Mefloquine-artesunate is a formulation of artemisinin based combination therapy (ACT recommended by the World Health Organization and historically the first ACT used clinically. The use of ACT demands constant monitoring of therapeutic efficacies and drug levels, in order to ensure that optimum drug exposure is achieved and detect reduced susceptibility to these drugs. Quantification of anti-malarial drugs in biological fluids other than blood would provide a more readily applicable method of therapeutic drug monitoring in developing endemic countries. Efforts in this study were devoted to the development of a simple, field applicable, non-invasive method for assay of mefloquine in saliva. Methods A high performance liquid chromatographic method with UV detection at 220 nm for assaying mefloquine in saliva was developed and validated by comparing mefloquine concentrations in saliva and plasma samples from four healthy volunteers who received single oral dose of mefloquine. Verapamil was used as internal standard. Chromatographic separation was achieved using a Hypersil ODS column. Results Extraction recoveries of mefloquine in plasma or saliva were 76-86% or 83-93% respectively. Limit of quantification of mefloquine was 20 ng/ml. Agreement between salivary and plasma mefloquine concentrations was satisfactory (r = 0.88, p Conclusion Disposition of mefloquine in saliva paralleled that in plasma, making salivary quantification of mefloquine potentially useful in therapeutic drug monitoring.

  5. Single Laboratory Validation of A Ready-to-Use Phosphatase Inhibition Assay for Detection of Okadaic Acid Toxins

    Directory of Open Access Journals (Sweden)

    Luis Mata

    2012-04-01

    Full Text Available A phosphatase inhibition assay for detection of okadaic acid (OA toxins in shellfish, OkaTest, was single laboratory validated according to international recognized guidelines (AOAC, EURACHEM. Special emphasis was placed on the ruggedness of the method and stability of the components. All reagents were stable for more than 6 months and the method was highly robust under normal laboratory conditions. The limit of detection and quantification were 44 and 56 µg/kg, respectively; both below the European legal limit of 160 µg/kg. The repeatability was evaluated with 2 naturally contaminated samples. The relative standard deviation (RSD calculated was 1.4% at a level of 276 µg/kg and 3.9% at 124 µg/kg. Intermediate precision was estimated by testing 10 different samples (mussel and scallop on three different days and ranged between 2.4 and 9.5%. The IC50 values of the phosphatase used in this assay were determined for OA (1.2 nM, DTX-1 (1.6 nM and DTX-2 (1.2 nM. The accuracy of the method was estimated by recovery testing for OA (mussel, 78–101%; king scallop, 98–114%, DTX-1 (king scallop, 79–102% and DTX-2 (king scallop, 93%. Finally, the method was qualitatively compared to the mouse bioassay and LC-MS/MS.

  6. Micropillar arrays enabling single microbial cell encapsulation in hydrogels.

    Science.gov (United States)

    Park, Kyun Joo; Lee, Kyoung G; Seok, Seunghwan; Choi, Bong Gill; Lee, Moon-Keun; Park, Tae Jung; Park, Jung Youn; Kim, Do Hyun; Lee, Seok Jae

    2014-06-07

    Single microbial cell encapsulation in hydrogels is an important task to find valuable biological resources for human welfare. The conventional microfluidic designs are mainly targeted only for highly dispersed spherical bioparticles. Advanced structures should be taken into consideration for handling such aggregated and non-spherical microorganisms. Here, to address the challenge, we propose a new type of cylindrical-shaped micropillar array in a microfluidic device for enhancing the dispersion of cell clusters and the isolation of individual cells into individual micro-hydrogels for potential practical applications. The incorporated micropillars act as a sieve for the breaking of Escherichia coli (E. coli) clusters into single cells in a polymer mixture. Furthermore, the combination of hydrodynamic forces and a flow-focusing technique will improve the probability of encapsulation of a single cell into each hydrogel with a broad range of cell concentrations. This proposed strategy and device would be a useful platform for genetically modified microorganisms for practical applications.

  7. Rapid automation of a cell-based assay using a modular approach: case study of a flow-based Varicella Zoster Virus infectivity assay.

    Science.gov (United States)

    Joelsson, Daniel; Gates, Irina V; Pacchione, Diana; Wang, Christopher J; Bennett, Philip S; Zhang, Yuhua; McMackin, Jennifer; Frey, Tina; Brodbeck, Kristin C; Baxter, Heather; Barmat, Scott L; Benetti, Luca; Bodmer, Jean-Luc

    2010-06-01

    Vaccine manufacturing requires constant analytical monitoring to ensure reliable quality and a consistent safety profile of the final product. Concentration and bioactivity of active components of the vaccine are key attributes routinely evaluated throughout the manufacturing cycle and for product release and dosage. In the case of live attenuated virus vaccines, bioactivity is traditionally measured in vitro by infection of susceptible cells with the vaccine followed by quantification of virus replication, cytopathology or expression of viral markers. These assays are typically multi-day procedures that require trained technicians and constant attention. Considering the need for high volumes of testing, automation and streamlining of these assays is highly desirable. In this study, the automation and streamlining of a complex infectivity assay for Varicella Zoster Virus (VZV) containing test articles is presented. The automation procedure was completed using existing liquid handling infrastructure in a modular fashion, limiting custom-designed elements to a minimum to facilitate transposition. In addition, cellular senescence data provided an optimal population doubling range for long term, reliable assay operation at high throughput. The results presented in this study demonstrate a successful automation paradigm resulting in an eightfold increase in throughput while maintaining assay performance characteristics comparable to the original assay. Copyright 2010 Elsevier B.V. All rights reserved.

  8. A multiplex bead-based suspension array assay for interrogation of phylogenetically informative single nucleotide polymorphisms for Bacillus anthracis

    DEFF Research Database (Denmark)

    Thierry, Simon; Hamidjaja, Raditijo A.; Girault, Guillaume

    2013-01-01

    Single nucleotide polymorphisms (SNPs) are abundant in genomes of all species and represent informative DNA markers extensively used to analyze phylogenetic relationships between strains. Medium to high throughput, open methodologies able to test many SNPs in a minimum time are therefore in great...... been modified and adapted for simultaneous interrogation of 13 biallelic canonical SNPs in a 13-plex assay. Changes made to the originally published method include the design of allele-specific dual-priming-oligonucleotides (DPOs) as competing detection probes (MOLigo probes) and use of asymmetric PCR...... laboratories. While cost-effective compared to other singleplex methods, the present MOL-PCR method offers a high degree of flexibility and scalability. It can easily accommodate newly identified SNPs to increase resolving power to the canSNP typing of B. anthracis....

  9. Guidelines for the use and interpretation of assays for monitoring cell death in higher eukaryotes.

    Science.gov (United States)

    Galluzzi, L; Aaronson, S A; Abrams, J; Alnemri, E S; Andrews, D W; Baehrecke, E H; Bazan, N G; Blagosklonny, M V; Blomgren, K; Borner, C; Bredesen, D E; Brenner, C; Castedo, M; Cidlowski, J A; Ciechanover, A; Cohen, G M; De Laurenzi, V; De Maria, R; Deshmukh, M; Dynlacht, B D; El-Deiry, W S; Flavell, R A; Fulda, S; Garrido, C; Golstein, P; Gougeon, M-L; Green, D R; Gronemeyer, H; Hajnóczky, G; Hardwick, J M; Hengartner, M O; Ichijo, H; Jäättelä, M; Kepp, O; Kimchi, A; Klionsky, D J; Knight, R A; Kornbluth, S; Kumar, S; Levine, B; Lipton, S A; Lugli, E; Madeo, F; Malomi, W; Marine, J-C W; Martin, S J; Medema, J P; Mehlen, P; Melino, G; Moll, U M; Morselli, E; Nagata, S; Nicholson, D W; Nicotera, P; Nuñez, G; Oren, M; Penninger, J; Pervaiz, S; Peter, M E; Piacentini, M; Prehn, J H M; Puthalakath, H; Rabinovich, G A; Rizzuto, R; Rodrigues, C M P; Rubinsztein, D C; Rudel, T; Scorrano, L; Simon, H-U; Steller, H; Tschopp, J; Tsujimoto, Y; Vandenabeele, P; Vitale, I; Vousden, K H; Youle, R J; Yuan, J; Zhivotovsky, B; Kroemer, G

    2009-08-01

    Cell death is essential for a plethora of physiological processes, and its deregulation characterizes numerous human diseases. Thus, the in-depth investigation of cell death and its mechanisms constitutes a formidable challenge for fundamental and applied biomedical research, and has tremendous implications for the development of novel therapeutic strategies. It is, therefore, of utmost importance to standardize the experimental procedures that identify dying and dead cells in cell cultures and/or in tissues, from model organisms and/or humans, in healthy and/or pathological scenarios. Thus far, dozens of methods have been proposed to quantify cell death-related parameters. However, no guidelines exist regarding their use and interpretation, and nobody has thoroughly annotated the experimental settings for which each of these techniques is most appropriate. Here, we provide a nonexhaustive comparison of methods to detect cell death with apoptotic or nonapoptotic morphologies, their advantages and pitfalls. These guidelines are intended for investigators who study cell death, as well as for reviewers who need to constructively critique scientific reports that deal with cellular demise. Given the difficulties in determining the exact number of cells that have passed the point-of-no-return of the signaling cascades leading to cell death, we emphasize the importance of performing multiple, methodologically unrelated assays to quantify dying and dead cells.

  10. New insights into human primordial germ cells and early embryonic development from single-cell analysis.

    Science.gov (United States)

    Otte, Jörg; Wruck, Wasco; Adjaye, James

    2017-08-01

    Human preimplantation developmental studies are difficult to accomplish due to associated ethical and moral issues. Preimplantation cells are rare and exist only in transient cell states. From a single cell, it is very challenging to analyse the origination of the heterogeneity and complexity inherent to the human body. However, recent advances in single-cell technology and data analysis have provided new insights into the process of early human development and germ cell specification. In this Review, we examine the latest single-cell datasets of human preimplantation embryos and germ cell development, compare them to bulk cell analyses, and interpret their biological implications. © 2017 Federation of European Biochemical Societies.

  11. Solar cell structure incorporating a novel single crystal silicon material

    Science.gov (United States)

    Pankove, Jacques I.; Wu, Chung P.

    1983-01-01

    A novel hydrogen rich single crystal silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystal silicon without out-gassing the hydrogen. The new material can be used to fabricate semiconductor devices such as single crystal silicon solar cells with surface window regions having a greater band gap energy than that of single crystal silicon without hydrogen.

  12. Single-cell magnetic imaging using a quantum diamond microscope.

    Science.gov (United States)

    Glenn, D R; Lee, K; Park, H; Weissleder, R; Yacoby, A; Lukin, M D; Lee, H; Walsworth, R L; Connolly, C B

    2015-08-01

    We apply a quantum diamond microscope for detection and imaging of immunomagnetically labeled cells. This instrument uses nitrogen-vacancy (NV) centers in diamond for correlated magnetic and fluorescence imaging. Our device provides single-cell resolution and a field of view (∼1 mm(2)) two orders of magnitude larger than that of previous NV imaging technologies, enabling practical applications. To illustrate, we quantified cancer biomarkers expressed by rare tumor cells in a large population of healthy cells.

  13. Single cell magnetic imaging using a quantum diamond microscope

    Science.gov (United States)

    Park, H.; Weissleder, R.; Yacoby, A.; Lukin, M. D.; Lee, H.; Walsworth, R. L.; Connolly, C. B.

    2015-01-01

    We apply a quantum diamond microscope to detection and imaging of immunomagnetically labeled cells. This instrument uses nitrogen-vacancy (NV) centers in diamond for correlated magnetic and fluorescence imaging. Our device provides single-cell resolution and two orders of magnitude larger field of view (~1 mm2) than previous NV imaging technologies, enabling practical applications. To illustrate, we quantify cancer biomarkers expressed by rare tumor cells in a large population of healthy cells. PMID:26098019

  14. A Fluid Membrane-Based Soluble Ligand Display System for Live CellAssays

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Jwa-Min; Nair, Pradeep N.; Neve, Richard M.; Gray, Joe W.; Groves, Jay T.

    2005-10-14

    Cell communication modulates numerous biological processes including proliferation, apoptosis, motility, invasion and differentiation. Correspondingly, there has been significant interest in the development of surface display strategies for the presentation of signaling molecules to living cells. This effort has primarily focused on naturally surface-bound ligands, such as extracellular matrix components and cell membranes. Soluble ligands (e.g. growth factors and cytokines) play an important role in intercellular communications, and their display in a surface-bound format would be of great utility in the design of array-based live cell assays. Recently, several cell microarray systems that display cDNA, RNAi, or small molecules in a surface array format were proven to be useful in accelerating high-throughput functional genetic studies and screening therapeutic agents. These surface display methods provide a flexible platform for the systematic, combinatorial investigation of genes and small molecules affecting cellular processes and phenotypes of interest. In an analogous sense, it would be an important advance if one could display soluble signaling ligands in a surface assay format that allows for systematic, patterned presentation of soluble ligands to live cells. Such a technique would make it possible to examine cellular phenotypes of interest in a parallel format with soluble signaling ligands as one of the display parameters. Herein we report a ligand-modified fluid supported lipid bilayer (SLB) assay system that can be used to functionally display soluble ligands to cells in situ (Figure 1A). By displaying soluble ligands on a SLB surface, both solution behavior (the ability to become locally enriched by reaction-diffusion processes) and solid behavior (the ability to control the spatial location of the ligands in an open system) could be combined. The method reported herein benefits from the naturally fluid state of the supported membrane, which allows

  15. Single cell Hi-C reveals cell-to-cell variability in chromosome structure

    Science.gov (United States)

    Schoenfelder, Stefan; Yaffe, Eitan; Dean, Wendy; Laue, Ernest D.; Tanay, Amos; Fraser, Peter

    2013-01-01

    Large-scale chromosome structure and spatial nuclear arrangement have been linked to control of gene expression and DNA replication and repair. Genomic techniques based on chromosome conformation capture assess contacts for millions of loci simultaneously, but do so by averaging chromosome conformations from millions of nuclei. Here we introduce single cell Hi-C, combined with genome-wide statistical analysis and structural modeling of single copy X chromosomes, to show that individual chromosomes maintain domain organisation at the megabase scale, but show variable cell-to-cell chromosome territory structures at larger scales. Despite this structural stochasticity, localisation of active gene domains to boundaries of territories is a hallmark of chromosomal conformation. Single cell Hi-C data bridge current gaps between genomics and microscopy studies of chromosomes, demonstrating how modular organisation underlies dynamic chromosome structure, and how this structure is probabilistically linked with genome activity patterns. PMID:24067610

  16. Value of a gene signature assay in patients with early breast cancer and intermediate risk: a single institution retrospective study.

    Science.gov (United States)

    Bonneterre, Jacques; Prat, Aleix; Galván, Patricia; Morel, Pascale; Giard, Sylvia

    2016-05-01

    Purpose In daily clinical practice, the indication for adjuvant chemotherapy (CT) is relatively easy to make in patients with early hormone-receptor-positive (HR+) breast cancer with either very poor or very good clinicopathological prognostic variables. However, this decision is much more difficult in patients with intermediate clinicopathological prognostic variables. Here, we evaluate the value of a gene-expression profile identified by the Prosigna gene signature assay in guiding treatment decision-making in patients with these intermediate features. Methods A consecutive cohort of 577 HR + breast cancer patients surgically treated in a single institution between January 2012 and December 2012 was evaluated. From this population, pre- and post-menopausal patients with intermediate prognosis clinicopathological variables were identified and indication of adjuvant CT in these patients was recorded. The gene signature assay was performed retrospectively in this intermediate risk group. Descriptive statistics are presented. Results Among 96 intermediate-risk patients, 64 postmenopausal patients underwent gene signature testing. Subtype distribution was as follows: Luminal A (N = 33; 51.6%), Luminal B (N = 31; 48.4%). Risk of recurrence (ROR) distribution was as follows: ROR-low (n = 16; 25%); ROR-intermediate (N = 26; 40.6%); and ROR-high (N = 22; 34.4%). CT was subsequently administered in 18.7%, 53.8% and 59.0% of the ROR-low, ROR-intermediate and ROR-high groups, respectively. With the use of the gene signature assay, 59.4% of the intermediate cases were re-classified to either ROR-low or ROR-high risk categories. In the ROR-intermediate group, 11/26 patients (42.3%) had Luminal A and 15/26 (57.7%) had Luminal B. Due to follow-up time constraints, no patient outcome results were evaluated. Conclusion The gene signature assay provides clinically useful information and improved treatment decision-making in patients with intermediate risk based on

  17. Functional Insights into Sponge Microbiology by Single Cell Genomics

    KAUST Repository

    Hentschel, Ute

    2011-04-09

    Marine Sponges (Porifera) are known to harbor enormous amounts of microorganisms with members belonging to at least 30 different bacterial phyla including several candidate phyla and both archaeal lineages. Here, we applied single cell genomics to the mic

  18. Evaluation of royal jelly as an alternative to fetal bovine serum in cell culture using cell proliferation assays and live cell imaging.

    Science.gov (United States)

    Musa, Marahaini; Nasir, Nurul Fatihah Mohamad; Thirumulu, Kannan Ponnuraj

    2014-01-01

    Royal jelly is a nutritious substance produced by the young nurse bees and contains significant amounts of proteins which are important for cell growth and proliferation. The aim of this study was to evaluate the effect of royal jelly as an alternative to fetal bovine serum (FBS) in cell culture using cell proliferation assays and live cell imaging. MRC-5 cells were treated with various concentrations of royal jelly extract in MTT assay. The control groups were comprised of Alpha-Minimal Essential Medium (α-MEM) alone and α-MEM with 10% FBS. Subsequently, the cell proliferation was studied for 10 days using Alamar Blue assay and live cell imaging from 48 to 72 h. The population doubling time (PDT) was determined using trypan blue assay after live cell imaging. In MTT assay, 0.156 and 0.078 mg/ml of royal jelly produced higher cell viability compared to positive control group but were not significantly different (P > 0.05). In the Alamar Blue assay, 0.156 and 0.078 mg/ml of royal jelly produced greater percentage of reduction at day 3 even though no significant difference was found (P > 0.05). Based on live cell imaging, the PDT for positive, negative, 0.156 and 0.078 mg/ml of royal jelly groups were 29.09, 62.50, 41.67 and 41.67 h respectively. No significant difference was found in the PDT between all the groups (P > 0.05). Royal jelly does not exhibit similar ability like FBS to facilitate cell growth under the present test conditions.

  19. Tumor Heterogeneity, Single-Cell Sequencing, and Drug Resistance

    Directory of Open Access Journals (Sweden)

    Felix Schmidt

    2016-06-01

    Full Text Available Tumor heterogeneity has been compared with Darwinian evolution and survival of the fittest. The evolutionary ecosystem of tumors consisting of heterogeneous tumor cell populations represents a considerable challenge to tumor therapy, since all genetically and phenotypically different subpopulations have to be efficiently killed by therapy. Otherwise, even small surviving subpopulations may cause repopulation and refractory tumors. Single-cell sequencing allows for a better understanding of the genomic principles of tumor heterogeneity and represents the basis for more successful tumor treatments. The isolation and sequencing of single tumor cells still represents a considerable technical challenge and consists of three major steps: (1 single cell isolation (e.g., by laser-capture microdissection, fluorescence-activated cell sorting, micromanipulation, whole genome amplification (e.g., with the help of Phi29 DNA polymerase, and transcriptome-wide next generation sequencing technologies (e.g., 454 pyrosequencing, Illumina sequencing, and other systems. Data demonstrating the feasibility of single-cell sequencing for monitoring the emergence of drug-resistant cell clones in patient samples are discussed herein. It is envisioned that single-cell sequencing will be a valuable asset to assist the design of regimens for personalized tumor therapies based on tumor subpopulation-specific genetic alterations in individual patients.

  20. Comparison of cell-based assays for the identification and evaluation of competitive CXCR4 inhibitors.

    Directory of Open Access Journals (Sweden)

    Anneleen Van Hout

    Full Text Available The chemokine receptor CXCR4 is activated by its unique chemokine ligand CXCL12 and regulates many physiological and developmental processes such as hematopoietic cell trafficking. CXCR4 is also one of the main co-receptors for human immunodeficiency virus (HIV entry. Dysfunction of the CXCL12/CXCR4 axis contributes to several human pathologies, including cancer and inflammatory diseases. Consequently, inhibition of CXCR4 activation is recognized as an attractive target for therapeutic intervention. In this regard, numerous agents modifying CXCR4 activity have been evaluated in in vitro experimental studies and pre-clinical models. Here, we evaluated a CXCL12 competition binding assay for its potential as a valuable initial screen for functional and competitive CXCR4 inhibitors. In total, 11 structurally diverse compounds were included in a side-by-side comparison of in vitro CXCR4 cell-based assays, such as CXCL12 competition binding, CXCL12-induced calcium signaling, CXCR4 internalization, CXCL12-guided cell migration and CXCR4-specific HIV-1 replication experiments. Our data indicated that agents that inhibit CXCL12 binding, i.e. the anti-CXCR4 peptide analogs T22, T140 and TC14012 and the small molecule antagonists AMD3100, AMD3465, AMD11070 and IT1t showed inhibitory activity with consistent relative potencies in all further applied CXCR4-related assays. Accordingly, agents exerting no or very weak receptor binding (i.e., CTCE-9908, WZ811, Me6TREN and gambogic acid showed no or very poor anti-CXCR4 inhibitory activity. Thus, CXCL12 competition binding studies were proven to be highly valuable as an initial screening assay and indicative for the pharmacological and functional profile of competitive CXCR4 antagonists, which will help the design of new potent CXCR4 inhibitors.

  1. Assay based on electrical impedance spectroscopy to discriminate between normal and cancerous mammalian cells

    Science.gov (United States)

    Giana, Fabián Eduardo; Bonetto, Fabián José; Bellotti, Mariela Inés

    2018-03-01

    In this work we present an assay to discriminate between normal and cancerous cells. The method is based on the measurement of electrical impedance spectra of in vitro cell cultures. We developed a protocol consisting on four consecutive measurement phases, each of them designed to obtain different information about the cell cultures. Through the analysis of the measured data, 26 characteristic features were obtained for both cell types. From the complete set of features, we selected the most relevant in terms of their discriminant capacity by means of conventional statistical tests. A linear discriminant analysis was then carried out on the selected features, allowing the classification of the samples in normal or cancerous with 4.5% of false positives and no false negatives.

  2. Limit-dilution assay and clonal expansion of all T cells capable of proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.F.; Wilson, A.; Scollay, R.; Shortman, K. (Walter and Eliza Hall Inst. of Medical Research, Parkville (Australia))

    1982-08-13

    A limit-dilution microculture system is presented in which almost all mature T cells, cultured at a level of about 1 cell/well, grow and expand to clones averaging 60,000 cells over an 8-9 day period. Cloning efficiency is 70-100%, so the set of expanded clones is representative of the starting T-cell population. T cells of all Lyt phenotypes form clones of progeny cells. The system involves culture in flat-bottom microtitre trays, in the presence of concanavalin A as the initiating stimulus, together with appropriately irradiated spleen filler cells and a supplementary source of soluble T cell growth factors. The resultant clones may be screened for cytolytic function, as described in the accompanying paper. The system may be used to assay the level of T cells capable of expansion or precursor function (PTL-p) by using (/sup 3/H)TdR uptake as a readout for the presence or absence of proliferating clones. Analysis of the frequency of positive cultures shows a good fit to the expected Poisson distribution, with no evidence of complicating suppressor or helper effects.

  3. Limit-dilution assay and clonal expansion of all T cells capable of proliferation

    International Nuclear Information System (INIS)

    Chen, W.-F.; Wilson, A.; Scollay, R.; Shortman, K.

    1982-01-01

    A limit-dilution microculture system is presented in which almost all mature T cells, cultured at a level of about 1 cell/well, grow and expand to clones averaging 60,000 cells over an 8-9 day period. Cloning efficiency is 70-100%, so the set of expanded clones is representative of the starting T-cell population. T cells of all Lyt phenotypes form clones of progeny cells. The system involves culture in flat-bottom microtitre trays, in the presence of concanavalin A as the initiating stimulus, together with appropriately irradiated spleen filler cells and a supplementary source of soluble T cell growth factors. The resultant clones may be screened for cytolytic function, as described in the accompanying paper. The system may be used to assay the level of T cells capable of expansion or precursor function (PTL-p) by using [ 3 H]TdR uptake as a readout for the presence or absence of proliferating clones. Analysis of the frequency of positive cultures shows a good fit to the expected Poisson distribution, with no evidence of complicating suppressor or helper effects. (Auth.)

  4. CellAnimation: an open source MATLAB framework for microscopy assays.

    Science.gov (United States)

    Georgescu, Walter; Wikswo, John P; Quaranta, Vito

    2012-01-01

    Advances in microscopy technology have led to the creation of high-throughput microscopes that are capable of generating several hundred gigabytes of images in a few days. Analyzing such wealth of data manually is nearly impossible and requires an automated approach. There are at present a number of open-source and commercial software packages that allow the user to apply algorithms of different degrees of sophistication to the images and extract desired metrics. However, the types of metrics that can be extracted are severely limited by the specific image processing algorithms that the application implements, and by the expertise of the user. In most commercial software, code unavailability prevents implementation by the end user of newly developed algorithms better suited for a particular type of imaging assay. While it is possible to implement new algorithms in open-source software, rewiring an image processing application requires a high degree of expertise. To obviate these limitations, we have developed an open-source high-throughput application that allows implementation of different biological assays such as cell tracking or ancestry recording, through the use of small, relatively simple image processing modules connected into sophisticated imaging pipelines. By connecting modules, non-expert users can apply the particular combination of well-established and novel algorithms developed by us and others that are best suited for each individual assay type. In addition, our data exploration and visualization modules make it easy to discover or select specific cell phenotypes from a heterogeneous population. CellAnimation is distributed under the Creative Commons Attribution-NonCommercial 3.0 Unported license (http://creativecommons.org/licenses/by-nc/3.0/). CellAnimationsource code and documentation may be downloaded from www.vanderbilt.edu/viibre/software/documents/CellAnimation.zip. Sample data are available at www

  5. New and cost effective cell-based assay for Dialyzed Leukocyte Extract (DLE)-induced Jurkat cells proliferation under azathioprine treatment.

    Science.gov (United States)

    Cardoso, F M; Tomkova, M; Petrovajova, D; Bubanova, M; Ragac, O; Hornakova, T

    2017-05-10

    The human Dialyzed Leukocyte Extract (DLE) is a heterogeneous mix of oligopeptides of cell-based assay. The A20 and Jurkat cell lines were treated with (+Aza) or without (-Aza) azathioprine, DLE (+DLE) or both (+Aza/+DLE). After 72h, the cell proliferation was analyzed by the MTT or BrdU incorporation assays. In +Aza/+DLE treated cells, we observed a significant higher proliferation, when compared with +Aza/-DLE. In the absence of Aza, cells did not present any proliferation difference between -DLE or +DLE treatments. Both assays, MTT and BrdU showed similar results, being the MTT test more cost effective and we select it for validation as DLE biological assay using Jurkat cells only. We tested three different lyophilized DLE batches and we found consistent results with acceptable assay reproducibility and linearity. The DLE capacity for rescuing Jurkat cell proliferation during +Aza treatment was consistent using different liquid and lyophilized DLE batches, presenting also consistent chromatographic profiles. Finally, DLE treatment in Jurkat cells did not result into significant IL-2 of IFN-γ secretion, and known lymphocyte proliferative drugs failed to rescue Jurkat cells viability in presence of +Aza, as +DLE treatment did in our MTT assay. In conclusion, our new cell-based MTT assay has excellent DLE biological activity consistency, robustness and is cost effective, presenting important advantages over previous DLE activity in vitro and in vivo assays. Copyright © 2017. Published by Elsevier B.V.

  6. Single-cell analysis of targeted transcriptome predicts drug sensitivity of single cells within human myeloma tumors.

    Science.gov (United States)

    Mitra, A K; Mukherjee, U K; Harding, T; Jang, J S; Stessman, H; Li, Y; Abyzov, A; Jen, J; Kumar, S; Rajkumar, V; Van Ness, B

    2016-05-01

    Multiple myeloma (MM) is characterized by significant genetic diversity at subclonal levels that have a defining role in the heterogeneity of tumor progression, clinical aggressiveness and drug sensitivity. Although genome profiling studies have demonstrated heterogeneity in subclonal architecture that may ultimately lead to relapse, a gene expression-based prediction program that can identify, distinguish and quantify drug response in sub-populations within a bulk population of myeloma cells is lacking. In this study, we performed targeted transcriptome analysis on 528 pre-treatment single cells from 11 myeloma cell lines and 418 single cells from 8 drug-naïve MM patients, followed by intensive bioinformatics and statistical analysis for prediction of proteasome inhibitor sensitivity in individual cells. Using our previously reported drug response gene expression profile signature at the single-cell level, we developed an R Statistical analysis package available at https://github.com/bvnlabSCATTome, SCATTome (single-cell analysis of targeted transcriptome), that restructures the data obtained from Fluidigm single-cell quantitative real-time-PCR analysis run, filters missing data, performs scaling of filtered data, builds classification models and predicts drug response of individual cells based on targeted transcriptome using an assortment of machine learning methods. Application of SCATT should contribute to clinically relevant analysis of intratumor heterogeneity, and better inform drug choices based on subclonal cellular responses.

  7. TaqMan real-time PCR assays for single-nucleotide polymorphisms which identify Francisella tularensis and its subspecies and subpopulations.

    Directory of Open Access Journals (Sweden)

    Dawn N Birdsell

    Full Text Available Francisella tularensis, the etiologic agent of tularemia and a Class A Select Agent, is divided into three subspecies and multiple subpopulations that differ in virulence and geographic distribution. Given these differences, there is a need to rapidly and accurately determine if a strain is F. tularensis and, if it is, assign it to subspecies and subpopulation. We designed TaqMan real-time PCR genotyping assays using eleven single nucleotide polymorphisms (SNPs that were potentially specific to closely related groups within the genus Francisella, including numerous subpopulations within F. tularensis species. We performed extensive validation studies to test the specificity of these SNPs to particular populations by screening the assays across a set of 565 genetically and geographically diverse F. tularensis isolates and an additional 21 genetic near-neighbor (outgroup isolates. All eleven assays correctly determined the genetic groups of all 565 F. tularensis isolates. One assay differentiates F. tularensis, F. novicida, and F. hispaniensis from the more genetically distant F. philomiragia and Francisella-like endosymbionts. Another assay differentiates F. tularensis isolates from near neighbors. The remaining nine assays classify F. tularensis-confirmed isolates into F. tularensis subspecies and subpopulations. The genotyping accuracy of these nine assays diminished when tested on outgroup isolates (i.e. non F. tularensis, therefore a hierarchical approach of assay usage is recommended wherein the F. tularensis-specific assay is used before the nine downstream assays. Among F. tularensis isolates, all eleven assays were highly sensitive, consistently amplifying very low concentrations of DNA. Altogether, these eleven TaqMan real-time PCR assays represent a highly accurate, rapid, and sensitive means of identifying the species, subspecies, and subpopulation of any F. tularensis isolate if used in a step-wise hierarchical scheme. These assays

  8. Clustering Single-Cell Expression Data Using Random Forest Graphs.

    Science.gov (United States)

    Pouyan, Maziyar Baran; Nourani, Mehrdad

    2017-07-01

    Complex tissues such as brain and bone marrow are made up of multiple cell types. As the study of biological tissue structure progresses, the role of cell-type-specific research becomes increasingly important. Novel sequencing technology such as single-cell cytometry provides researchers access to valuable biological data. Applying machine-learning techniques to these high-throughput datasets provides deep insights into the cellular landscape of the tissue where those cells are a part of. In this paper, we propose the use of random-forest-based single-cell profiling, a new machine-learning-based technique, to profile different cell types of intricate tissues using single-cell cytometry data. Our technique utilizes random forests to capture cell marker dependences and model the cellular populations using the cell network concept. This cellular network helps us discover what cell types are in the tissue. Our experimental results on public-domain datasets indicate promising performance and accuracy of our technique in extracting cell populations of complex tissues.

  9. Protein-carbohydrate complex reveals circulating metastatic cells in a microfluidic assay

    KAUST Repository

    Simone, Giuseppina

    2013-02-11

    Advances in carbohydrate sequencing technologies reveal the tremendous complexity of the glycome and the role that glycomics might have to bring insight into the biological functions. Carbohydrate-protein interactions, in particular, are known to be crucial to most mammalian physiological processes as mediators of cell adhesion and metastasis, signal transducers, and organizers of protein interactions. An assay is developed here to mimic the multivalency of biological complexes that selectively and sensitively detect carbohydrate-protein interactions. The binding of β-galactosides and galectin-3 - a protein that is correlated to the progress of tumor and metastasis - is examined. The efficiency of the assay is related to the expression of the receptor while anchoring to the interaction\\'s strength. Comparative binding experiments reveal molecular binding preferences. This study establishes that the assay is robust to isolate metastatic cells from colon affected patients and paves the way to personalized medicine. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Repopulation in the SCCVII squamous cell carcinoma assessed by an in vivo-in vitro excision assay

    International Nuclear Information System (INIS)

    Hansen, Olfred; Grau, Cai; Bentzen, Soeren M.; Overgaard, Jens

    1996-01-01

    An in vivo-in vitro excision assay was used to study repopulation after a single dose of clamped irradiation (40 Gy) in the SCCVII tumour implanted in the foot of C3H/Km mice. The growth pattern of clonogenic cells was analysed by two different mathematical models: the logistic model and the Gompertz model. The logistic model described the data better than the Gompertz model. Accelerated repopulation was found when the regrowth rate after irradiation was compared to the growth rate at the time of treatment, and when it was compared to the growth rate in untreated tumours with a number of cells equivalent to the number that was found after irradiation. The clonogenic doubling time (cDT) was estimated at 15.1 h (95% c.i.: 14.2; 16.0) after irradiation, and 27.8 h (95% c.i.: 16.7; 43.5) in untreated controls of matching size. However, the estimate relies on the mathematical model chosen and on extrapolation below actually measured data. A small cDT points to shortening of the cell cycle time and recruitment of non-cycling clonogenic tumour cells to be the main mechanism behind the accelerated repopulation

  11. Sensitive Cell-Based Assay for Determination of Human Immunodeficiency Virus Type 1 Coreceptor Tropism

    Science.gov (United States)

    Weber, Jan; Vazquez, Ana C.; Winner, Dane; Gibson, Richard M.; Rhea, Ariel M.; Rose, Justine D.; Wylie, Doug; Henry, Kenneth; Wright, Alison; King, Kevin; Archer, John; Poveda, Eva; Soriano, Vicente; Robertson, David L.; Olivo, Paul D.; Arts, Eric J.

    2013-01-01

    CCR5 antagonists are a powerful new class of antiretroviral drugs that require a companion assay to evaluate the presence of CXCR4-tropic (non-R5) viruses prior to use in human immunodeficiency virus (HIV)-infected individuals. In this study, we have developed, characterized, verified, and prevalidated a novel phenotypic test to determine HIV-1 coreceptor tropism (VERITROP) based on a sensitive cell-to-cell fusion assay. A proprietary vector was constructed containing a near-full-length HIV-1 genome with the yeast uracil biosynthesis (URA3) gene replacing the HIV-1 env coding sequence. Patient-derived HIV-1 PCR products were introduced by homologous recombination using an innovative yeast-based cloning strategy. The env-expressing vectors were then used in a cell-to-cell fusion assay to determine the presence of R5 and/or non-R5 HIV-1 variants within the viral population. Results were compared with (i) the original version of Trofile (Monogram Biosciences, San Francisco, CA), (ii) population sequencing, and (iii) 454 pyrosequencing, with the genotypic data analyzed using several bioinformatics tools, i.e., the 11/24/25 rule, Geno2Pheno (2% to 5.75%, 3.5%, or 10% false-positive rate [FPR]), and webPSSM. VERITROP consistently detected minority non-R5 variants from clinical specimens, with an analytical sensitivity of 0.3%, with viral loads of ≥1,000 copies/ml, and from B and non-B subtypes. In a pilot study, a 73.7% (56/76) concordance was observed with the original Trofile assay, with 19 of the 20 discordant results corresponding to non-R5 variants detected using VERITROP and not by the original Trofile assay. The degree of concordance of VERITROP and Trofile with population and deep sequencing results depended on the algorithm used to determine HIV-1 coreceptor tropism. Overall, VERITROP showed better concordance with deep sequencing/Geno2Pheno at a 0.3% detection threshold (67%), whereas Trofile matched better with population sequencing (79%). However, 454

  12. A buccal cell model comet assay: Development and evaluation for human biomonitoring and nutritional studies

    Energy Technology Data Exchange (ETDEWEB)

    Szeto, Y.T. [Department of Health Technology and Informatics, Hong Kong Polytechnic University, Kowloon, Hong Kong (China); School of Health Sciences, Macao Polytechnic Institute, Macao (China); Benzie, I.F.F. [Department of Health Technology and Informatics, Hong Kong Polytechnic University, Kowloon, Hong Kong (China)]. E-mail: iris.benzie@inet.polyu.edu.hk; Collins, A.R. [Department of Nutrition, University of Oslo, Oslo (Norway); Choi, S.W. [Department of Health Technology and Informatics, Hong Kong Polytechnic University, Kowloon, Hong Kong (China); Cheng, C.Y. [Department of Health Technology and Informatics, Hong Kong Polytechnic University, Kowloon, Hong Kong (China); Yow, C.M.N. [Department of Health Technology and Informatics, Hong Kong Polytechnic University, Kowloon, Hong Kong (China); Tse, M.M.Y. [School of Nursing, Hong Kong Polytechnic University, Kowloon, Hong Kong (China)

    2005-10-15

    The comet assay is a widely used biomonitoring tool for DNA damage. The most commonly used cells in human studies are lymphocytes. There is an urgent need to find an alternative target human cell that can be collected from normal subjects with minimal invasion. There are some reports of buccal cells, collected easily from the inside of the mouth, being used in studies of DNA damage and repair, and these were of interest. However, our preliminary studies following the published protocol showed that buccal cells sustained massive damage and disintegrated at the high pH [O. Ostling, K.J. Johanson. Microelectrophoretic study of radiation-induced DNA damages in individual mammalian cells. Biochem. Biophys. Res. Commun. 123 (1984) 291-298] used, but that at lower pH were extremely resistant to lysis, an essential step in the comet assay. Therefore, the aims of this study were to develop a protocol than enabled buccal cell lysis and DNA damage testing in the comet assay, and to use the model to evaluate the potential use of the buccal cell model in human biomonitoring and nutritional study. Specifically, we aimed to investigate intra- and inter-individual differences in buccal cell DNA damage (as strand breaks), the effect of in vitro exposure to both a standard oxidant challenge and antioxidant treatment, as well as in situ exposure to an antioxidant-rich beverage and supplementation-related effects using a carotenoid-rich food. Successful lysis was achieved using 0.25% trypsin for 30 min followed by proteinase K (1 mg/ml) treatment for 60 min. When this procedure was performed on cells pre-embedded in agarose on a microscope slide, followed by electrophoresis (in 0.01 M NaOH, 1 mM EDTA, pH 9.1, 18 min at 12 V), a satisfactory comet image was obtained, though inter-individual variation was quite wide. Pre-lysis exposure of cells to a standard oxidant challenge (induced by H{sub 2}O{sub 2}) increased DNA strand breaks in a dose related manner, and incubation of cells in

  13. A buccal cell model comet assay: Development and evaluation for human biomonitoring and nutritional studies

    International Nuclear Information System (INIS)

    Szeto, Y.T.; Benzie, I.F.F.; Collins, A.R.; Choi, S.W.; Cheng, C.Y.; Yow, C.M.N.; Tse, M.M.Y.

    2005-01-01

    The comet assay is a widely used biomonitoring tool for DNA damage. The most commonly used cells in human studies are lymphocytes. There is an urgent need to find an alternative target human cell that can be collected from normal subjects with minimal invasion. There are some reports of buccal cells, collected easily from the inside of the mouth, being used in studies of DNA damage and repair, and these were of interest. However, our preliminary studies following the published protocol showed that buccal cells sustained massive damage and disintegrated at the high pH [O. Ostling, K.J. Johanson. Microelectrophoretic study of radiation-induced DNA damages in individual mammalian cells. Biochem. Biophys. Res. Commun. 123 (1984) 291-298] used, but that at lower pH were extremely resistant to lysis, an essential step in the comet assay. Therefore, the aims of this study were to develop a protocol than enabled buccal cell lysis and DNA damage testing in the comet assay, and to use the model to evaluate the potential use of the buccal cell model in human biomonitoring and nutritional study. Specifically, we aimed to investigate intra- and inter-individual differences in buccal cell DNA damage (as strand breaks), the effect of in vitro exposure to both a standard oxidant challenge and antioxidant treatment, as well as in situ exposure to an antioxidant-rich beverage and supplementation-related effects using a carotenoid-rich food. Successful lysis was achieved using 0.25% trypsin for 30 min followed by proteinase K (1 mg/ml) treatment for 60 min. When this procedure was performed on cells pre-embedded in agarose on a microscope slide, followed by electrophoresis (in 0.01 M NaOH, 1 mM EDTA, pH 9.1, 18 min at 12 V), a satisfactory comet image was obtained, though inter-individual variation was quite wide. Pre-lysis exposure of cells to a standard oxidant challenge (induced by H 2 O 2 ) increased DNA strand breaks in a dose related manner, and incubation of cells in Trolox

  14. White blood cell-based detection of asymptomatic scrapie infection by ex vivo assays.

    Directory of Open Access Journals (Sweden)

    Sophie Halliez

    Full Text Available Prion transmission can occur by blood transfusion in human variant Creutzfeldt-Jakob disease and in experimental animal models, including sheep. Screening of blood and its derivatives for the presence of prions became therefore a major public health issue. As infectious titer in blood is reportedly low, highly sensitive and robust methods are required to detect prions in blood and blood derived products. The objectives of this study were to compare different methods--in vitro, ex vivo and in vivo assays--to detect prion infectivity in cells prepared from blood samples obtained from scrapie infected sheep at different time points of the disease. Protein misfolding cyclic amplification (PMCA and bioassays in transgenic mice expressing the ovine prion protein were the most efficient methods to identify infected animals at any time of the disease (asymptomatic to terminally-ill stages. However scrapie cell and cerebellar organotypic slice culture assays designed to replicate ovine prions in culture also allowed detection of prion infectivity in blood cells from asymptomatic sheep. These findings confirm that white blood cells are appropriate targets for preclinical detection and introduce ex vivo tools to detect blood infectivity during the asymptomatic stage of the disease.

  15. Development of a whole-cell-based screening method for a carotenoid assay using aerial microalgae.

    Science.gov (United States)

    Aburai, Nobuhiro; Kazama, Hiroaki; Tsuruoka, Atsushi; Goto, Mizuki; Abe, Katsuya

    2018-02-20

    Non-destructive approaches based on the application of optical spectroscopy are important for monitoring carotenoid accumulation in a whole cell cultured under various conditions. A simple and rapid assay utilizing aerial microalgae helps to identify stress conditions that can efficiently enhance the carotenogenesis in photosynthetic organisms. The spectra of cell suspensions were characterized in the aerial microalga Coelastrella sp. KGU-Y002, which are unicellular and undifferentiated. Total carotenoid contents could be successfully estimated on the basis of the absorbance values of the cell suspensions and calibration data analyzed by HPLC (high-performance liquid chromatography). A novel screening method, the so-called "whole-cell-based screening method" for carotenoid assays (WCA), was developed based on this procedure. It was possible to investigate the effects of various stresses on carotenoid accumulation in the aerial microalga by adapting this bioassay to a 96-well microtiter plate. When bioactive compounds were screened from our library of plant extracts using this method, an active compound was identified from the plant extract. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Effects of Plantago major L. leaf extracts on oral epithelial cells in a scratch assay.

    Science.gov (United States)

    Zubair, Muhammad; Ekholm, Anders; Nybom, Hilde; Renvert, Stefan; Widen, Cecilia; Rumpunen, Kimmo

    2012-06-14

    The present study was undertaken to evaluate the effects from different leaf extracts of the traditional medicinal herb Plantago major L. (plantain) on cell proliferation and migration in vitro, as a test for potential wound healing properties. Water and ethanol-based extracts were prepared from Plantago major fresh and dried leaves, and tested in vitro in a scratch assay with oral epithelial cells. The scratch assay produced reliable results after 18 h. Most of the tested extracts increased the proliferation/migration of the oral epithelial cells compared to the negative control. A concentration of 1.0 mg/mL (on dry weight basis) appears to be optimal regardless of type of extract, and among the alternatives, 0.1 mg/mL was always better than 10 mg/mL. Ethanol-based extracts with a concentration of 10 mg/mL had very detrimental effects on cell proliferation/migration. At the other two concentrations, ethanol-based extracts had the most beneficial effect, followed by water extracts of fresh leaves, ethanol plus water extracts of dried leaves and, finally, water extracts of dried leaves. This study suggests that both the water extracts and the more polyphenol-rich ethanol-based extracts of Plantago major leaves have medicinal properties. Further research is, however, needed to determine what compounds are responsible for the wound healing effects. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  17. Statistical techniques to construct assays for identifying likely responders to a treatment under evaluation from cell line genomic data

    International Nuclear Information System (INIS)

    Huang, Erich P; Fridlyand, Jane; Lewin-Koh, Nicholas; Yue, Peng; Shi, Xiaoyan; Dornan, David; Burington, Bart

    2010-01-01

    Developing the right drugs for the right patients has become a mantra of drug development. In practice, it is very difficult to identify subsets of patients who will respond to a drug under evaluation. Most of the time, no single diagnostic will be available, and more complex decision rules will be required to define a sensitive population, using, for instance, mRNA expression, protein expression or DNA copy number. Moreover, diagnostic development will often begin with in-vitro cell-line data and a high-dimensional exploratory platform, only later to be transferred to a diagnostic assay for use with patient samples. In this manuscript, we present a novel approach to developing robust genomic predictors that are not only capable of generalizing from in-vitro to patient, but are also amenable to clinically validated assays such as qRT-PCR. Using our approach, we constructed a predictor of sensitivity to dacetuzumab, an investigational drug for CD40-expressing malignancies such as lymphoma using genomic measurements of cell lines treated with dacetuzumab. Additionally, we evaluated several state-of-the-art prediction methods by independently pairing the feature selection and classification components of the predictor. In this way, we constructed several predictors that we validated on an independent DLBCL patient dataset. Similar analyses were performed on genomic measurements of breast cancer cell lines and patients to construct a predictor of estrogen receptor (ER) status. The best dacetuzumab sensitivity predictors involved ten or fewer genes and accurately classified lymphoma patients by their survival and known prognostic subtypes. The best ER status classifiers involved one or two genes and led to accurate ER status predictions more than 85% of the time. The novel method we proposed performed as well or better than other methods evaluated. We demonstrated the feasibility of combining feature selection techniques with classification methods to develop assays

  18. Label-free profiling of cell dynamics: A sequence of impedance-based assays to estimate tumor cell invasiveness in vitro.

    Science.gov (United States)

    Láng, Orsolya; Kőhidai, László; Wegener, Joachim

    2017-10-01

    Dynamic properties of cancer cells, most notably their ability to migrate, have been correlated successfully with their invasive nature in vivo. To establish a stronger experimental basis for such a correlation we subjected five different cancer cell lines of well-defined metastatic potential to a sequence of three independent assays reporting on three different aspects of cell dynamics, namely (1) the kinetics of cell spreading, (2) cell shape fluctuations, and (3) cell migration. The sequentially applied assays correspond to different measuring modes of the well-established ECIS technique that is based on non-invasive and label-free impedance readings of planar gold-film electrodes that serve as the growth substrate for the cells under study. Every individual assay returned a characteristic parameter describing the behavior of the cell lines in that particular assay quantitatively. The parameters of all three assays were ranked to establish individual profiles of cell dynamics for every cell line that correlate favorably with the cells' invasive properties. The sequence of impedance-based assays described here requires only small cell populations (< 10.000 cells), it is highly automated and easily adapted to 96-well formats. It provides an in-depth dynamic profile of adherent cells that might be useful in other areas besides cancer research as well. Copyright © 2017. Published by Elsevier Inc.

  19. Polymerase chain reaction assay for the detection of Bacillus cereus group cells

    DEFF Research Database (Denmark)

    Hansen, Bjarne Munk; Leser, Thomas D.; Hendriksen, Niels Bohse

    2001-01-01

    of the B. cereus group in food and in the environment. Using 16S rDNA as target, a PCR assay for the detection of B. cereus group cells has been developed. Primers specific for the 16S rDNA of the B. cereus group bacteria were selected and used in combination with consensus primers for 165 rDNA as internal...... PCR procedure control. The PCR procedure was optimized with respect to annealing temperature. When DNA from the B. cereus group bacteria was present, the PCR assay yielded a B. cereus specific fragment, while when non-B. cereus prokaryotic DNA was present, the consensus 165 rDNA primers directed...

  20. Identification of novel bacterial histidine biosynthesis inhibitors using docking, ensemble rescoring, and whole-cell assays

    DEFF Research Database (Denmark)

    Henriksen, Signe Teuber; Liu, J.; Estiu, G.

    2010-01-01

    The rapid spread on multidrug-resistant strains of Staphylococcus aureus requires not just novel treatment options, but the development of faster methods for the identification of new hits for drug development. The exponentially increasing speed of computational methods makes a more extensive use...... in the early stages of drug discovery attractive if sufficient accuracy can be achieved. Computational target identification using systems-level methods suggested the histidine biosynthesis pathway as an attractive target against S. aureus. Potential inhibitors for the pathway were identified through docking......, followed by ensemble rescoring, that is sufficiently accurate to justify immediate testing of the identified compounds by whole-cell assays, avoiding the need for time-consuming and often difficult intermediary enzyme assays. This novel strategy is demonstrated for three key enzymes of the S. aureus...

  1. Single Cell Characterization of Prostate Cancer-Circulating Tumor Cells

    Science.gov (United States)

    2013-09-01

    contaminating WBC. Scale bar = 20 microns. (E) MagSweeper versus CellSearch comparison. Samples with 0 CTC were assigned a value of 1. 10...cancer patient blood sample, and contaminating WBC found after MagSweeper isolation. Scale bar = 20 microns. (E) MagSweeper versus CellSearch...Weinberg RA (2011) Hallmarks of cancer: the next generation. Cell 144: 646–674. 4. Ashworth TR (1869) A case of cancer in which cells similar to those in

  2. Single cell transcriptome profiling of developing chick retinal cells.

    Science.gov (United States)

    Laboissonniere, Lauren A; Martin, Gregory M; Goetz, Jillian J; Bi, Ran; Pope, Brock; Weinand, Kallie; Ellson, Laura; Fru, Diane; Lee, Miranda; Wester, Andrea K; Liu, Peng; Trimarchi, Jeffrey M

    2017-08-15

    The vertebrate retina is a specialized photosensitive tissue comprised of six neuronal and one glial cell types, each of which develops in prescribed proportions at overlapping timepoints from a common progenitor pool. While each of these cells has a specific function contributing to proper vision in the mature animal, their differential representation in the retina as well as the presence of distinctive cellular subtypes makes identifying the transcriptomic signatures that lead to each retinal cell's fate determination and development challenging. We have analyzed transcriptomes from individual cells isolated from the chick retina throughout retinogenesis. While we focused our efforts on the retinal ganglion cells, our transcriptomes of developing chick cells also contained representation from multiple retinal cell types, including photoreceptors and interneurons at different stages of development. Most interesting was the identification of transcriptomes from individual mixed lineage progenitor cells in the chick as these cells offer a window into the cell fate decision-making process. Taken together, these data sets will enable us to uncover the most critical genes acting in the steps of cell fate determination and early differentiation of various retinal cell types. © 2017 Wiley Periodicals, Inc.

  3. Visualization of multivalent histone modification in a single cell reveals highly concerted epigenetic changes on differentiation of embryonic stem cells

    DEFF Research Database (Denmark)

    Hattori, Naoko; Niwa, Tohru; Kimura, Kana

    2013-01-01

    . Bivalent modification was clearly visualized by iChmo in wild-type embryonic stem cells (ESCs) known to have it, whereas rarely in Suz12 knockout ESCs and mouse embryonic fibroblasts known to have little of it. iChmo was applied to analysis of epigenetic and phenotypic changes of heterogeneous cell......Combinations of histone modifications have significant biological roles, such as maintenance of pluripotency and cancer development, but cannot be analyzed at the single cell level. Here, we visualized a combination of histone modifications by applying the in situ proximity ligation assay, which...... population, namely, ESCs at an early stage of differentiation, and this revealed that the bivalent modification disappeared in a highly concerted manner, whereas phenotypic differentiation proceeded with large variations among cells. Also, using this method, we were able to visualize a combination...

  4. Magnetic domain wall conduits for single cell applications

    DEFF Research Database (Denmark)

    Donolato, Marco; Torti, A.; Kostesha, Natalie

    2011-01-01

    The ability to trap, manipulate and release single cells on a surface is important both for fundamental studies of cellular processes and for the development of novel lab-on-chip miniaturized tools for biological and medical applications. In this paper we demonstrate how magnetic domain walls...... walls technology in lab-on-chip systems devoted to accurate individual cell trapping and manipulation....

  5. Electrochemical Quantification of Extracellular Local H2O2 Kinetics Originating from Single Cells.

    Science.gov (United States)

    Bozem, Monika; Knapp, Phillip; Mirčeski, Valentin; Slowik, Ewa J; Bogeski, Ivan; Kappl, Reinhard; Heinemann, Christian; Hoth, Markus

    2017-05-15

    H 2 O 2 is produced by all eukaryotic cells under physiological and pathological conditions. Due to its enormous relevance for cell signaling at low concentrations and antipathogenic function at high concentrations, precise quantification of extracellular local H 2 O 2 concentrations ([H 2 O 2 ]) originating from single cells is required. Using a scanning electrochemical microscope and bare platinum disk ultramicroelectrodes, we established sensitive long-term measurements of extracellular [H 2 O 2 ] kinetics originating from single primary human monocytes (MCs) ex vivo. For the electrochemical techniques square wave voltammetry, cyclic and linear scan voltammetry, and chronoamperometry, detection limits for [H 2 O 2 ] were determined to be 5, 50, and 500 nM, respectively. Following phorbol ester stimulation, local [H 2 O 2 ] 5-8 μm above a single MC increased by 3.4 nM/s within the first 10 min before reaching a plateau. After extracellular addition of H 2 O 2 to an unstimulated MC, the local [H 2 O 2 ] decreased on average by 4.2 nM/s due to degradation processes of the cell. Using the scanning mode of the setup, we found that H 2 O 2 is evenly distributed around the producing cell and can still be detected up to 30 μm away from the cell. The electrochemical single-cell measurements were validated in MC populations using electron spin resonance spectroscopy and the Amplex ® UltraRed assay. Innovation and Conclusion: We demonstrate a highly sensitive, spatially, and temporally resolved electrochemical approach to monitor dynamics of production and degradation processes for H 2 O 2 separately. Local extracellular [H 2 O 2 ] kinetics originating from single cells is quantified in real time. Antioxid. Redox Signal. 00, 000-000.

  6. Rapid alternative to the clonogenic assay for measuring antibody and complement-mediated killing of tumor cells

    International Nuclear Information System (INIS)

    Gee, A.P.; Rolfe, A.E.; Worthington-White, D.; Graham-Pole, J.; Boyle, M.D.

    1985-01-01

    A study of the methods used to quantitate killing of tumor cells by antibody and complement has highlighted a number of problems. Using leukemia as a model, the authors have found that the release of 51 Cr from labeled tumor cells treated with antibody and complement can be an equivocal measure of cell viability. Combined with its restricted sensitivity (less than a 2 log range of cell killing) this makes this widely used assay of questionable value for detecting small numbers of viable cells, or for identifying subpopulations of complement-resistant cells. As an alternative a [ 125 I]iododeoxyuridine uptake assay has been developed, that combines the simplicity and rapidity of the 51 Cr release technique with the sensitivity of a clonogenic assay. This method eliminates the problem of spontaneous isotope release, inherent in prelabeling assays, and variability from experiment to experiment can be avoided by including a viable cell standard curve within each assay. The sensitivity of the 125 IUdR uptake method, which can be completed within a day, is similar to that of a 10 day methylcellulose cloning assay and was capable of detecting the presence of a minor subpopulation of complement-resistant tumor cells

  7. DNA-based mutation assay GPMA (genome profiling-based mutation assay): reproducibility, parts-per-billion scale sensitivity, and introduction of a mammalian-cell-based approach.

    Science.gov (United States)

    Kumari, Parmila; Gautam, Sunita Ghimire; Baba, Misato; Tsukiashi, Motoki; Matsuoka, Koji; Yasukawa, Kiyoshi; Nishigaki, Koichi

    2017-12-01

    Genome profiling-based mutation assay (GPMA) is, to date, the only DNA sequence-based mutation assay that directly measures DNA alterations induced by mutagens. Here, the all-important congruence of mutagen assignment between DNA-based GPMA and the phenotype-based Ames test (the gold standard of mutagen assays) was confirmed qualitatively and semi-quantitatively by means of 94 chemical species (including previously examined 64). The high sensitivity (on the order of 10 ppb) and reproducibility of GPMA were also corroborated by the match between virtually independent experiments conducted in the distant past (10 years ago) and recently. Meanwhile, a standard experimental framework was established: the conditions of 100 parts per billion (ppb) concentration of a chemical and 15-generation culture of Escherichia coli. Moreover, a mammalian cell line (NIH 3T3) was shown to be suitable as a tester organism for the GPMA approach. Preliminary experimental results suggested that this approach can provide a qualitatively equivalent and quantitatively different mutagen assay results relative to the bacteria-based GPMA (renamed as bGPMA). This finding confirmed the effectiveness of the GPMA approach and indicates that mGPMA is a promising way to detect mammalian-cell mutagens. © The Authors 2017. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

  8. Optimizing and accelerating the assignation of lineages in Mycobacterium tuberculosis using novel alternative single-tube assays.

    Directory of Open Access Journals (Sweden)

    María Carcelén

    Full Text Available The assignation of lineages in Mycobacterium tuberculosis (MTB provides valuable information for evolutionary and phylogeographic studies and makes for more accurate knowledge of the distribution of this pathogen worldwide. Differences in virulence have also been found for certain lineages. MTB isolates were initially assigned to lineages based on data obtained from genotyping techniques, such as spoligotyping or MIRU-VNTR analysis, some of which are more suitable for molecular epidemiology studies. However, since these methods are subject to a certain degree of homoplasy, other criteria have been chosen to assign lineages. These are based on targeting robust and specific SNPs for each lineage. Here, we propose two newly designed multiplex targeting methods-both of which are single-tube tests-to optimize the assignation of the six main lineages in MTB. The first method is based on ASO-PCR and offers an inexpensive and easy-to-implement assay for laboratories with limited resources. The other, which is based on SNaPshot, enables more refined standardized assignation of lineages for laboratories with better resources. Both methods performed well when assigning lineages from cultured isolates from a control panel, a test panel, and a problem panel from an unrelated population, Mexico, which included isolates in which standard genotyping was not able to classify lineages. Both tests were also able to assign lineages from stored isolates, without the need for subculture or purification of DNA, and even directly from clinical specimens with a medium-high bacilli burden. Our assays could broaden the contexts where information on lineages can be acquired, thus enabling us to quickly update data from retrospective collections and to merge data with those obtained at the time of diagnosis of a new TB case.

  9. Fluorine nuclear magnetic resonance-based assay in living mammalian cells.

    Science.gov (United States)

    Veronesi, Marina; Giacomina, Francesca; Romeo, Elisa; Castellani, Beatrice; Ottonello, Giuliana; Lambruschini, Chiara; Garau, Gianpiero; Scarpelli, Rita; Bandiera, Tiziano; Piomelli, Daniele; Dalvit, Claudio

    2016-02-15

    Nuclear magnetic resonance (NMR)-based screening has been recognized as a powerful approach for the identification and characterization of molecules interacting with pharmaceutical targets. Indeed, several NMR methods have been developed and successfully applied to many drug discovery projects. Whereas most of these approaches have targeted isolated biomolecular receptors, very few cases are reported with the screening performed in intact cells and cell extracts. Here we report the first successful application of the fluorine NMR-based assay n-FABS (n-fluorine atoms for biochemical screening) in living mammalian cells expressing the membrane protein fatty acid amide hydrolase (FAAH). This method allows the identification of both weak and potent inhibitors and the measurement of their potency in a physiological environment. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Large-scale prospective T cell function assays in shipped, unfrozen blood samples

    DEFF Research Database (Denmark)

    Hadley, David; Cheung, Roy K; Becker, Dorothy J

    2014-01-01

    , for measuring core T cell functions. The Trial to Reduce Insulin-dependent diabetes mellitus in the Genetically at Risk (TRIGR) type 1 diabetes prevention trial used consecutive measurements of T cell proliferative responses in prospectively collected fresh heparinized blood samples shipped by courier within...... cell immunocompetence. We have found that the vast majority of the samples were viable up to 3 days from the blood draw, yet meaningful responses were found in a proportion of those with longer travel times. Furthermore, the shipping time of uncooled samples significantly decreased both the viabilities...... North America. In this article, we report on the quality control implications of this simple and pragmatic shipping practice and the interpretation of positive- and negative-control analytes in our assay. We used polyclonal and postvaccination responses in 4,919 samples to analyze the development of T...

  11. Radionuclide assay of membrane Na+, K+-ATPase activity of peserved red blood cells

    International Nuclear Information System (INIS)

    Trusov, V.V.; Zelenin, A.A.; Marizin, S.A.

    1986-01-01

    The radionuclide tests were used to investigate the influence of varying blood preservatives on erythrocylic membrane Na + , K + -ATPase activity in samples of whole blood and packed red blood cells from normal donors prepared by standard methods. The tests were performed before and after seven days of preservation under standard conditions. It was found that blood preservations lowered membrane Na + , K + -ATPase activity: its minimum reduction was recorded with citroglucopnosphate, while glugicir induced a significant drop in Na + , K + -ATPase activity of preserved red blood cells regardless of the type of the blood transfusion solution. The assay of membrane Na + , K + -ATPase activity of preserved red blood cells with the use of 86 Rb could be recommended as an evaluation test for preserved blood and its components

  12. Novel approaches in function-driven single-cell genomics.

    Science.gov (United States)

    Doud, Devin F R; Woyke, Tanja

    2017-07-01

    Deeper sequencing and improved bioinformatics in conjunction with single-cell and metagenomic approaches continue to illuminate undercharacterized environmental microbial communities. This has propelled the 'who is there, and what might they be doing' paradigm to the uncultivated and has already radically changed the topology of the tree of life and provided key insights into the microbial contribution to biogeochemistry. While characterization of 'who' based on marker genes can describe a large fraction of the community, answering 'what are they doing' remains the elusive pinnacle for microbiology. Function-driven single-cell genomics provides a solution by using a function-based screen to subsample complex microbial communities in a targeted manner for the isolation and genome sequencing of single cells. This enables single-cell sequencing to be focused on cells with specific phenotypic or metabolic characteristics of interest. Recovered genomes are conclusively implicated for both encoding and exhibiting the feature of interest, improving downstream annotation and revealing activity levels within that environment. This emerging approach has already improved our understanding of microbial community functioning and facilitated the experimental analysis of uncharacterized gene product space. Here we provide a comprehensive review of strategies that have been applied for function-driven single-cell genomics and the future directions we envision. © FEMS 2017.

  13. A phosphorescent iridium(III) solvent complex for multiplex assays of cell death.

    Science.gov (United States)

    Chen, Min; Wu, Yongquan; Liu, Yi; Yang, Huiran; Zhao, Qiang; Li, Fuyou

    2014-10-01

    Cell death involves loss of transport function and physical integrity of the plasma membrane, and plays a critical role in many human diseases. At present, the development of an effective visualization tool to monitor cell death remains a significant challenge. Here, a cyclometalated iridium(III) solvent complex [Ir(pdz)2(H2O)2](+)[OTf](-) (IrC1) was designed and synthesized as a phosphorescent indicator of cell death. IrC1 specifically stained the nuclei of dead cells over living cells rapidly (<10 min) and at low concentrations (10 μM), as observed using confocal luminescence microscopy. Moreover, the IrC1 uptake behavior leads to its further application in quantifying the population of early apoptotic cells using flow cytometry. In particular, successful application in time-gated fluorescence microscopy by virtue of its microsecond lifetime rendered IrC1 attractive as a luminescent probe. IrC1 additionally exhibited excellent long-term photostability, in contrast to traditional dyes. We conclude that in combination with luminescent microscopy and flow cytometry, IrC1 provides an effective, straightforward alternative to cell death assays. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Validation of T47D-KBluc cell assay for detection of estrogen receptor agonists and antagonists

    Science.gov (United States)

    There is growing concern of exposure to fish, wildlife, and humans to environmental estrogens and their potential impact on reproductive health. Cell-based assays are useful tools to determine the estrogenic activity of chemicals. Confidence in in vitro assay results is strengthe...

  15. Validation of T47D-KBluc cell assay for detection of estrogen receptor agonists and antagonists###

    Science.gov (United States)

    There is growing concern of exposure to fish, wildlife, and humans to environmental estrogens and their potential impact on reproductive health. Cell-based assays are useful tools to determine the estrogenic activity of chemicals. Confidence in in vitro assay results is strengthe...

  16. Novel migrating mouse neural crest cell assay system utilizing P0-Cre/EGFP fluorescent time-lapse imaging

    Directory of Open Access Journals (Sweden)

    Kawakami Minoru

    2011-11-01

    Full Text Available Abstract Background Neural crest cells (NCCs are embryonic, multipotent stem cells. Their long-range and precision-guided migration is one of their most striking characteristics. We previously reported that P0-Cre/CAG-CAT-lacZ double-transgenic mice showed significant lacZ expression in tissues derived from NCCs. Results In this study, by embedding a P0-Cre/CAG-CAT-EGFP embryo at E9.5 in collagen gel inside a culture glass slide, we were able to keep the embryo developing ex vivo for more than 24 hours; this development was with enough NCC fluorescent signal intensity to enable single-cell resolution analysis, with the accompanying NCC migration potential intact and with the appropriate NCC response to the extracellular signal maintained. By implantation of beads with absorbed platelet-derived growth factor-AA (PDGF-AA, we demonstrated that PDGF-AA acts as an NCC-attractant in embryos. We also performed assays with NCCs isolated from P0-Cre/CAG-CAT-EGFP embryos on culture plates. The neuromediator 5-hydroxytryptamine (5-HT has been known to regulate NCC migration. We newly demonstrated that dopamine, in addition to 5-HT, stimulated NCC migration in vitro. Two NCC populations, with different axial levels of origins, showed unique distribution patterns regarding migration velocity and different dose-response patterns to both 5-HT and dopamine. Conclusions Although avian species predominated over the other species in the NCC study, our novel system should enable us to use mice to assay many different aspects of NCCs in embryos or on culture plates, such as migration, division, differentiation, and apoptosis.

  17. Single-cell sequencing of the small-RNA transcriptome.

    Science.gov (United States)

    Faridani, Omid R; Abdullayev, Ilgar; Hagemann-Jensen, Michael; Schell, John P; Lanner, Fredrik; Sandberg, Rickard

    2016-12-01

    Little is known about the heterogeneity of small-RNA expression as small-RNA profiling has so far required large numbers of cells. Here we present a single-cell method for small-RNA sequencing and apply it to naive and primed human embryonic stem cells and cancer cells. Analysis of microRNAs and fragments of tRNAs and small nucleolar RNAs (snoRNAs) reveals the potential of microRNAs as markers for different cell types and states.

  18. Review of methods to probe single cell metabolism and bioenergetics.

    Science.gov (United States)

    Vasdekis, Andreas E; Stephanopoulos, Gregory

    2015-01-01

    Single cell investigations have enabled unexpected discoveries, such as the existence of biological noise and phenotypic switching in infection, metabolism and treatment. Herein, we review methods that enable such single cell investigations specific to metabolism and bioenergetics. Firstly, we discuss how to isolate and immobilize individuals from a cell suspension, including both permanent and reversible approaches. We also highlight specific advances in microbiology for its implications in metabolic engineering. Methods for probing single cell physiology and metabolism are subsequently reviewed. The primary focus therein is on dynamic and high-content profiling strategies based on label-free and fluorescence microspectroscopy and microscopy. Non-dynamic approaches, such as mass spectrometry and nuclear magnetic resonance, are also briefly discussed. Published by Elsevier Inc.

  19. Comparison of the colony formation and crystal violet cell proliferation assays to determine cellular radiosensitivity in a repair-deficient MCF10A cell line

    Energy Technology Data Exchange (ETDEWEB)

    Vandersickel, Veerle [Department of Basic Medical Sciences, Ghent University, Campus Heymans, De Pintelaan 185 (6B3), 9000 Gent (Belgium); Slabbert, Jacobus [NRF iThemba LABS (Laboratory for Accelerated Based Sciences), PO box 722, 7129 Somerset West (South Africa); Thierens, Hubert [Department of Basic Medical Sciences, Ghent University, Campus Heymans, De Pintelaan 185 (6B3), 9000 Gent (Belgium); Vral, Anne, E-mail: anne.Vral@UGent.b [Department of Basic Medical Sciences, Ghent University, Campus Heymans, De Pintelaan 185 (6B3), 9000 Gent (Belgium)

    2011-01-15

    Colony formation as measured by the in vitro clonogenic assay is a very important endpoint to determine cellular radiosensitivity and tumor response to radiotherapy. In the framework of assessing in vitro cellular radiosensitivity, proliferation assays could represent an attractive alternative to the clonogenic assay for cell lines that do not form proper colonies. In the present study, we compared cellular radiosensitivity measurements obtained by the crystal violet (CV) cell proliferation assay and the standard colony formation assay in repair-deficient and-proficient human MCF10A cell lines. Compared to the clonogenic assay, the CV cell proliferation assay yielded higher surviving fractions for the same radiation dose. This is reflected in larger mean inactivation dose values - a parameter that reflects the area under the survival curve. However, as the dose modifying factors obtained by both assays are comparable, the CV cell proliferation assay can be used to compare the in vitro cellular radiosensitivity of cell lines that lack the ability to form well-defined colonies.

  20. Assay for identification of heterozygous single-nucleotide polymorphism (Ala67Thr in human poliovirus receptor gene

    Directory of Open Access Journals (Sweden)

    Shyam Sundar Nandi

    2016-01-01

    Results: A new SNP assay for detection of heterozygous Ala67Thr genotype was developed and validated by testing 150 DNA samples. Heterozygous CD155 was detected in 27.33 per cent (41/150 of DNA samples tested by both SNP detection assay and sequencing. Interpretation & conclusions: The SNP detection assay was successfully developed for identification of Ala67Thr polymorphism in human PVR/CD155 gene. The SNP assay will be useful for large scale screening of DNA samples.

  1. Distribution of inorganic elements in single cells of Chara corallina

    International Nuclear Information System (INIS)

    Li Zijie; Zhang Zhiyong; Chai Zhifang; Yu Ming; Zhou Yunlong

    2005-01-01

    There are actually 20 chemical elements necessary or beneficial for plant growth. Carbon, hydrogen, and oxygen are supplied by air and water. The six macronutrients, nitrogen, phosphorus, potassium., calcium, magnesium, and sulfur are required by plants in large amounts. The rest of the elements are required in trace amounts (micronutrients). Essential trace elements include boron, chlorine, copper, iron, manganese, sodium, zinc, molybdenum, and nickel. Beneficial mineral elements include silicon and cobalt. The functions of the inorganic elements closely related to their destinations in plant cells. Plant cells have unique structures, including a central vacuole, plastids, and a thick cell wall that surrounds the cell membrane. Generally, it is very difficult to determine concentrations of inorganic elements in a single plant cell. Chara corallina is a freshwater plant that inhabits temperate zone ponds and lakes. It consists of alternating nodes and internodes. Each internodal segment is a single large cell, up to 10 cm in length, and 1 mm in diameter. With this species it was possible to isolate subcellular fractions with surgical methods with minimal risk of cross contamination. In this study, concentrations of magnesium, calcium, manganese, iron, copper, zinc, and molybdenum in the cell wall, cytoplasm, and vacuole of single cells of Chara corallina were determined by inductively coupled plasma mass spectrometry (ICP-MS). The distribution characteristics of these elements in the cell components were discussed.

  2. Protein Signaling Networks from Single Cell Fluctuations and Information Theory Profiling

    Science.gov (United States)

    Shin, Young Shik; Remacle, F.; Fan, Rong; Hwang, Kiwook; Wei, Wei; Ahmad, Habib; Levine, R.D.; Heath, James R.

    2011-01-01

    Protein signaling networks among cells play critical roles in a host of pathophysiological processes, from inflammation to tumorigenesis. We report on an approach that integrates microfluidic cell handling, in situ protein secretion profiling, and information theory to determine an extracellular protein-signaling network and the role of perturbations. We assayed 12 proteins secreted from human macrophages that were subjected to lipopolysaccharide challenge, which emulates the macrophage-based innate immune responses against Gram-negative bacteria. We characterize the fluctuations in protein secretion of single cells, and of small cell colonies (n = 2, 3,···), as a function of colony size. Measuring the fluctuations permits a validation of the conditions required for the application of a quantitative version of the Le Chatelier's principle, as derived using information theory. This principle provides a quantitative prediction of the role of perturbations and allows a characterization of a protein-protein interaction network. PMID:21575571

  3. Optical scatter imaging: a microscopic modality for the rapid morphological assay of living cells

    Science.gov (United States)

    Boustany, Nada N.

    2007-02-01

    Tumors derived from epithelial cells comprise the majority of human tumors and their growth results from the accumulation of multiple mutations affecting cellular processes critical for tissue homeostasis, including cell proliferation and cell death. To understand these processes and address the complexity of cancer cell function, multiple cellular responses to different experimental conditions and specific genetic mutations must be analyzed. Fundamental to this endeavor is the development of rapid cellular assays in genetically defined cells, and in particular, the development of optical imaging methods that allow dynamic observation and real-time monitoring of cellular processes. In this context, we are developing an optical scatter imaging technology that is intended to bridge the gap between light and electron microscopy by rapidly providing morphometric information about the relative size and shape of non-spherical organelles, with sub-wavelength resolution. Our goal is to complement current microscopy techniques used to study cells in-vitro, especially in long-term time-lapse studies of living cells, where exogenous labels can be toxic, and electron microscopy will destroy the sample. The optical measurements are based on Fourier spatial filtering in a standard microscope, and could ultimately be incorporated into existing high-throughput diagnostic platforms for cancer cell research and histopathology of neoplastic tissue arrays. Using an engineered epithelial cell model of tumor formation, we are currently studying how organelle structure and function are altered by defined genetic mutations affecting the propensity for cell death and oncogenic potential, and by environmental conditions promoting tumor growth. This talk will describe our optical scatter imaging technology and present results from our studies on apoptosis, and the function of BCL-2 family proteins.

  4. Development of a Cell-Based Functional Assay for the Detection of Clostridium botulinum Neurotoxin Types A and E

    Directory of Open Access Journals (Sweden)

    Uma Basavanna

    2013-01-01

    Full Text Available The standard procedure for definitive detection of BoNT-producing Clostridia is a culture method combined with neurotoxin detection using a standard mouse bioassay (MBA. The mouse bioassay is highly sensitive and specific, but it is expensive and time-consuming, and there are ethical concerns due to use of laboratory animals. Cell-based assays provide an alternative to the MBA in screening for BoNT-producing Clostridia. Here, we describe a cell-based assay utilizing a fluorescence reporter construct expressed in a neuronal cell model to study toxin activity in situ. Our data indicates that the assay can detect as little as 100 pM BoNT/A activity within living cells, and the assay is currently being evaluated for the analysis of BoNT in food matrices. Among available in vitro assays, we believe that cell-based assays are widely applicable in high-throughput screenings and have the potential to at least reduce and refine animal assays if not replace it.

  5. Reliable single cell array CGH for clinical samples.

    Directory of Open Access Journals (Sweden)

    Zbigniew T Czyż

    Full Text Available BACKGROUND: Disseminated cancer cells (DCCs and circulating tumor cells (CTCs are extremely rare, but comprise the precursors cells of distant metastases or therapy resistant cells. The detailed molecular analysis of these cells may help to identify key events of cancer cell dissemination, metastatic colony formation and systemic therapy escape. METHODOLOGY/PRINCIPAL FINDINGS: Using the Ampli1™ whole genome amplification (WGA technology and high-resolution oligonucleotide aCGH microarrays we optimized conditions for the analysis of structural copy number changes. The protocol presented here enables reliable detection of numerical genomic alterations as small as 0.1 Mb in a single cell. Analysis of single cells from well-characterized cell lines and single normal cells confirmed the stringent quantitative nature of the amplification and hybridization protocol. Importantly, fixation and staining procedures used to detect DCCs showed no significant impact on the outcome of the analysis, proving the clinical usability of our method. In a proof-of-principle study we tracked the chromosomal changes of single DCCs over a full course of high-dose chemotherapy treatment by isolating and analyzing DCCs of an individual breast cancer patient at four different time points. CONCLUSIONS/SIGNIFICANCE: The protocol enables detailed genome analysis of DCCs and thereby assessment of the clonal evolution during the natural course of the disease and under selection pressures. The results from an exemplary patient provide evidence that DCCs surviving selective therapeutic conditions may be recruited from a pool of genomically less advanced cells, which display a stable subset of specific genomic alterations.

  6. Centrifugal multiplexing fixed-volume dispenser on a plastic lab-on-a-disk for parallel biochemical single-end-point assays.

    Science.gov (United States)

    La, Moonwoo; Park, Sang Min; Kim, Dong Sung

    2015-01-01

    In this study, a multiple sample dispenser for precisely metered fixed volumes was successfully designed, fabricated, and fully characterized on a plastic centrifugal lab-on-a-disk (LOD) for parallel biochemical single-end-point assays. The dispenser, namely, a centrifugal multiplexing fixed-volume dispenser (C-MUFID) was designed with microfluidic structures based on the theoretical modeling about a centrifugal circumferential filling flow. The designed LODs were fabricated with a polystyrene substrate through micromachining and they were thermally bonded with a flat substrate. Furthermore, six parallel metering and dispensing assays were conducted at the same fixed-volume (1.27 μl) with a relative variation of ±0.02 μl. Moreover, the samples were metered and dispensed at different sub-volumes. To visualize the metering and dispensing performances, the C-MUFID was integrated with a serpentine micromixer during parallel centrifugal mixing tests. Parallel biochemical single-end-point assays were successfully conducted on the developed LOD using a standard serum with albumin, glucose, and total protein reagents. The developed LOD could be widely applied to various biochemical single-end-point assays which require different volume ratios of the sample and reagent by controlling the design of the C-MUFID. The proposed LOD is feasible for point-of-care diagnostics because of its mass-producible structures, reliable metering/dispensing performance, and parallel biochemical single-end-point assays, which can identify numerous biochemical.

  7. The production of lymphokines by primary alloreactive T-cell clones: a co-ordinate analysis of 233 clones in seven lymphokine assays.

    Science.gov (United States)

    Sanderson, C J; Strath, M; Warren, D J; O'Garra, A; Kirkwood, T B

    1985-01-01

    A total of 233 primary alloreactive T-cell clones have been tested for the production of interleukin-2 (IL-2), interleukin-3 (IL-3), immune(gamma) interferon (IFN) and granulocyte-macrophage colony-stimulating factor (CSF-2), B-cell growth factor I and II (BCGFI, BCGFII), and eosinophil differentiation factor (EDF). EDF was assayed by means of the eosinophil differentiation assay (EDA). Two principal correlations were observed: IL-3 was shown to be the major lymphokine detected in the bone marrow proliferation assay (BMPA) used to detect CSF-2, and there was a high correlation between the EDA and BCGFII. Subsequent work has suggested that this latter correlation is because a single factor is responsible for both activities. Apart from these two exceptions, and low level correlations probably due to the fact that different assays detect more than one lymphokine, there was no evidence for co-ordinate expression of lymphokines. There was a large variation in amounts of individual lymphokines produced. More clones produced multiple lymphokines than would be expected from independent control. Taken together, this pattern of regulation is consistent with the hypothesis that antigen stimulation of T cells results in the activation of all the lymphokine genes, but the amount of each produced is determined by secondary controlling mechanisms. PMID:3935571

  8. Plate reader-based cell viability assays for glioprotection using primary rat optic nerve head astrocytes.

    Science.gov (United States)

    Kaja, Simon; Payne, Andrew J; Naumchuk, Yuliya; Levy, Deborah; Zaidi, Danish H; Altman, Alexa M; Nawazish, Saba; Ghuman, Jasleen K; Gerdes, Bryan C; Moore, Mark A; Koulen, Peter

    2015-09-01

    Optic nerve head astrocytes (ONHAs) are the major glia cell type in the non-myelinated optic nerve head where they contribute critically to extracellular matrix synthesis during development and throughout life. In glaucoma, and in related disorders affecting the optic nerve and the optic nerve head, pathological changes include altered astrocyte gene and protein expression resulting in their activation and extracellular matrix remodeling. ONHAs are highly sensitive to mechanical and oxidative stress resulting in the initiation of axon damage early during pathogenesis. Furthermore, ONHAs are crucial for the maintenance of retinal ganglion cell physiology and function. Therefore, glioprotective strategies with the goal to preserve and/or restore the structural and functional viability of ONHA in order to slow glaucoma and related pathologies are of high clinical relevance. Herein, we describe the development of standardized methods that will allow for the systematic advancement of such glioprotective strategies. These include isolation, purification and culture of primary adult rat ONHAs, optimized immunocytochemical protocols for cell type validation, as well as plate reader-based assays determining cellular viability, proliferation and the intracellular redox state. We validated and standardized our protocols by performing a glioprotection study using primary ONHAs. Specifically, we measured protection against exogenously-applied oxidative stress using tert-butylhydroperoxide (tBHP) as a model of disease-mediated oxidative stress in the retina and optic nerve head by the prototypic antioxidant, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). Levels of oxidative stress were increased in the response to exogenously applied tBHP and were assessed by 6-carboxy-2', 7' dichlorodihydrofluorescein diacetate (DCFDA) fluorescence. Normalized DCFDA fluorescence showed a maximal 5.1-fold increase; the half-maximal effect (EC50) for tBHP was 212 ± 25

  9. Counting Legionella cells within single amoeba host cells

    Science.gov (United States)

    Here we present the first attempt to quantify L. pneumophila cell numbers within individual amoebae hosts that may be released into engineered water systems. The maximum numbers of culturable L. pneumophila cells grown within Acanthamoeba polyphaga and Naegleria fowleri were 134...

  10. Toxicity evaluation of ZnO nanostructures on L929 fibroblast cell line using MTS assay

    Energy Technology Data Exchange (ETDEWEB)

    Bakhori, Siti Khadijah Mohd; Mahmud, Shahrom; Ann, Ling Chuo [Nano-optoelectronics Research and Technology Laboratory (NOR.), School of Physics, Universiti Sains Malaysia, 11800, USM, Pulau Pinang (Malaysia); Mohamed, Azman Seeni; Saifuddin, Siti Nazmin [Integrative Medicine Cluster, Advanced Medical and Dental Institute, Universiti Sains Malaysia, Bandar Putra Bertam, 13200 Kepala Batas, Pulau Pinang (Malaysia); Masudi, Sam’an Malik; Mohamad, Dasmawati [Craniofacial Science Laboratory, School of Dentistry, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

    2015-04-24

    ZnO has wide applications in medical and dentistry apart from being used as optoelectronic devices such as solar cells, photodetectors, sensors and light emitting diodes (LEDs). Therefore, the toxicity evaluation is important to know the toxicity level on normal cell line. The toxicity of two grades ZnO nanostructures, ZnO-4 and ZnO-8 have been carried out using cytotoxicity test of MTS assay on L929 rat fibroblast cell line. Prior to that, ZnO-4 and ZnO-8 were characterized for its morphology, structure and optical properties using FESEM, X-ray diffraction, and Photoluminescence respectively. The two groups revealed difference in morphology and exhibit slightly shifted of near band edge emission of Photoluminescence other than having a similar calculated crystallite size of nanostructures. The viability of cells after 72h were obtained and the statistical significance value was calculated using SPSS v20. The p value is more than 0.05 between untreated and treated cell with ZnO. This insignificant value of p>0.05 can be summarized as a non-toxic level of ZnO-4 and ZnO-8 on the L929 cell line.

  11. Cloning of Plasmodium falciparum by single-cell sorting

    Science.gov (United States)

    Miao, Jun; Li, Xiaolian; Cui, Liwang

    2010-01-01

    Malaria parasite cloning is traditionally carried out mainly by using the limiting dilution method, which is laborious, imprecise, and unable to distinguish multiply-infected RBCs. In this study, we used a parasite engineered to express green fluorescent protein (GFP) to evaluate a single-cell sorting method for rapidly cloning Plasmodium falciparum. By dividing a two dimensional scattergram from a cell sorter into 17 gates, we determined the parameters for isolating singly-infected erythrocytes and sorted them into individual cultures. Pre-gating of the engineered parasites for GFP allowed the isolation of almost 100% GFP-positive clones. Compared with the limiting dilution method, the number of parasite clones obtained by single-cell sorting was much higher. Molecular analyses showed that parasite isolates obtained by single-cell sorting were highly homogenous. This highly efficient single-cell sorting method should prove very useful for cloning both P. falciparum laboratory populations from genetic manipulation experiments and clinical samples. PMID:20435038

  12. T cell fate and clonality inference from single-cell transcriptomes.

    Science.gov (United States)

    Stubbington, Michael J T; Lönnberg, Tapio; Proserpio, Valentina; Clare, Simon; Speak, Anneliese O; Dougan, Gordon; Teichmann, Sarah A

    2016-04-01

    We developed TraCeR, a computational method to reconstruct full-length, paired T cell receptor (TCR) sequences from T lymphocyte single-cell RNA sequence data. TraCeR links T cell specificity with functional response by revealing clonal relationships between cells alongside their transcriptional profiles. We found that T cell clonotypes in a mouse Salmonella infection model span early activated CD4(+) T cells as well as mature effector and memory cells.

  13. DNA alkylation lesions and their repair in human cells: modification of the comet assay with 3-methyladenine DNA glycosylase (AlkD).

    Science.gov (United States)

    Hašplová, Katarína; Hudecová, Alexandra; Magdolénová, Zuzana; Bjøras, Magnar; Gálová, Eliška; Miadoková, Eva; Dušinská, Mária

    2012-01-05

    3-methyladenine DNA glycosylase (AlkD) belongs to a new family of DNA glycosylases; it initiates repair of cytotoxic and promutagenic alkylated bases (its main substrates being 3-methyladenine and 7-methylguanine). The modification of the comet assay (single cell gel electrophoresis) using AlkD enzyme thus allows assessment of specific DNA alkylation lesions. The resulting baseless sugars are alkali-labile, and under the conditions of the alkaline comet assay they appear as DNA strand breaks. The alkylating agent methyl methanesulfonate (MMS) was used to induce alkylation lesions and to optimize conditions for the modified comet assay method with AlkD on human lymphoblastoid (TK6) cells. We also studied cellular and in vitro DNA repair of alkylated bases in DNA in TK6 cells after treatment with MMS. Results from cellular repair indicate that 50% of DNA alkylation is repaired in the first 60 min. The in vitro repair assay shows that while AlkD recognises most alkylation lesions after 60 min, a cell extract from TK6 cells recognises most of the MMS-induced DNA adducts already in the first 15 min of incubation, with maximum detection of lesions after 60 min' incubation. Additionally, we tested the in vitro repair capacity of human lymphocyte extracts from 5 individuals and found them to be able to incise DNA alkylations in the same range as AlkD. The modification of the comet assay with AlkD can be useful for in vitro and in vivo genotoxicity studies to detect alkylation damage and repair and also for human biomonitoring and molecular epidemiology studies. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  14. Optimization of cytotoxicity assay by real-time, impedance-based cell analysis.

    Science.gov (United States)

    Ramis, G; Martínez-Alarcón, L; Quereda, J J; Mendonça, L; Majado, M J; Gomez-Coelho, K; Mrowiec, A; Herrero-Medrano, J M; Abellaneda, J M; Pallares, F J; Ríos, A; Ramírez, P; Muñoz, A

    2013-12-01

    This paper presents an optimized procedure for assessing an immune-mediated cytotoxicity, produced after the addition of human and baboon serum to transgenic porcine fibroblasts. This procedure is performed with the xCELLigence Real-Time Cell Analyzer (RTCA). The xCELLigence system measures the impedance variations in the culture media of a 96-well microelectronic plate, and shows the changes in cell number and morphology in a real-time plot. However, different factors need to be optimized before developing an RTCA assay. Thus, we studied the influence of several variables, such as the number of cells seeded, the time the cells were allowed to grow before the tests, the serum concentration and the addition of rabbit complement. The findings were confirmed by the WST-1 classical cytotoxicity test. The results showed that 7.5 × 10(3) cells seeded per well produced the adequate CI in 10 h. The area under the curve and the CImin versus concentration values showed a very high correlation index (r(2) = 0.966 and r(2) = 0.92 for the first 50 h after challenge, respectively), proving that CI variations are directly proportional to the quantity of serum added. The addition of complement resulted in lower CImin values. Therefore, both the cytolysis level with and without exogenous complement addition had to be assessed. There was a high correlation between the relative cytotoxicity assessed by WST-1 and the CI obtained by RTCA when exogenous complement was not added (r(2) = 0.827; p < 0.001). The correlation was average when rabbit complement was added (r(2) = 0.523; p = 0.046). In conclusion, culture conditions have an important influence on RTCA cytotoxicity assays.

  15. Single-cell screening of photosynthetic growth and lactate production by cyanobacteria

    DEFF Research Database (Denmark)

    Hammar, Petter; Angermayr, S. Andreas; Sjostrom, Staffan L.

    2015-01-01

    Background: Photosynthetic cyanobacteria are attractive for a range of biotechnological applications including biofuel production. However, due to slow growth, screening of mutant libraries using microtiter plates is not feasible.Results: We present a method for high-throughput, single......-cell analysis and sorting of genetically engineered l-lactate-producing strains of Synechocystis sp. PCC6803. A microfluidic device is used to encapsulate single cells in picoliter droplets, assay the droplets for L-lactate production, and sort strains with high productivity. We demonstrate the separation...... of low- and high-producing reference strains, as well as enrichment of a more productive L-lactate-synthesizing population after UV-induced mutagenesis. The droplet platform also revealed population heterogeneity in photosynthetic growth and lactate production, as well as the presence of metabolically...

  16. Clinical Applications of NanoVelcro Rare-Cell Assays for Detection and Characterization of Circulating Tumor Cells.

    Science.gov (United States)

    Chen, Jie-Fu; Zhu, Yazhen; Lu, Yi-Tsung; Hodara, Elisabeth; Hou, Shuang; Agopian, Vatche G; Tomlinson, James S; Posadas, Edwin M; Tseng, Hsian-Rong

    2016-01-01

    Liquid biopsy of tumor through isolation of circulating tumor cells (CTCs) allows non-invasive, repetitive, and systemic sampling of disease. Although detecting and enumerating CTCs is of prognostic significance in metastatic cancer, it is conceivable that performing molecular and functional characterization on CTCs will reveal unprecedented insight into the pathogenic mechanisms driving lethal disease. Nanomaterial-embedded cancer diagnostic platforms, i.e., NanoVelcro CTC Assays represent a unique rare-cell sorting method that enables detection isolation, and characterization of CTCs in peripheral blood, providing an opportunity to noninvasively monitor disease progression in individual cancer patients. Over the past decade, a series of NanoVelcro CTC Assays has been demonstrated for exploring the full potential of CTCs as a clinical biomarker, including CTC enumeration, phenotyping, genotyping and expression profiling. In this review article, the authors will briefly introduce the development of three generations of NanoVelcro CTC Assays, and highlight the clinical applications of each generation for various types of solid cancers, including prostate cancer, pancreatic cancer, lung cancer, and melanoma.

  17. Dosimetry of irradiation models. The 96-well clonogenic assay for testing radiosensitivity of cell lines

    International Nuclear Information System (INIS)

    Kulmala, J.; Rantanen, V.; Turku Univ.; Pekkola-Heino, K.; Turku Univ.; Tuominen, J.; Grenman, R.; Turku Univ.

    1995-01-01

    Radiation experiments with cells in single cell suspension in test tubes and on 96-well plates were carried out and compared. The cells originated from cell lines established from carcinomas of the floor of the mouth and from endometrical carcinoma. Two irradiation models were constructed. Both models allowed the absorbed doses to the cells to be administered with a high accuracy in both experimental settings (better than 5.0%). These irradiation models were compared on cancer cell lines with dissimilar inherent radiation sensitivity and histologic type (UM-SCC-1 resistant, UM-SCC-14A sensitive, and UT-EC-2B highly sensitive); various radiation doses were used. The fractions of surviving cells as a function of radiation dose were compared: there was no significant difference between cells irradiated in test tubes and cells irradiated in 96-well plates. Thus, if the absorbed doses in cells suspended in a tube and in a plate were the same, the survival was similar regardless of the type of irradiation model. (orig.)

  18. Honey is cytotoxic towards prostate cancer cells but interacts with the MTT reagent: Considerations for the choice of cell viability assay.

    Science.gov (United States)

    Abel, Sean D A; Baird, Sarah K

    2018-02-15

    Honey is a complex biological substance, consisting mainly of sugars, phenolic compounds and enzymes. Using five quick and accessible assays for measuring honey's cytotoxicity in vitro, we found honey is cytotoxic towards prostate cancer cells PC3 and DU145. However, the level of cell death varied with assay. The MTT assay was confounded by the reduction of the MTT reagent by honey's reducing sugars and phenolic compounds, and the lactate dehydrogenase assay was invalidated by honey oxidising the enzyme cofactor NADH. The sulforhodamine B assay gave valid results, but measures only protein content, providing no information about cell death in the remaining cells. The trypan blue assay and a microscope-based propidium iodide/Hoechst staining assay assess only late stage membrane permeability. However, the propidium iodide/Hoechst assay gives morphological information about cell death mechanism. A combination of the sulforhodamine B and propidium iodide/Hoechst assays would provide the most accurate quantification of honey cytotoxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Optimization and validation of a neutralizing antibody assay for HIV-1 in A3R5 cells.

    Science.gov (United States)

    Sarzotti-Kelsoe, Marcella; Daniell, Xiaoju; Todd, Christopher A; Bilska, Miroslawa; Martelli, Amanda; LaBranche, Celia; Perez, Lautaro G; Ochsenbauer, Christina; Kappes, John C; Rountree, Wes; Denny, Thomas N; Montefiori, David C

    2014-07-01

    A3R5 is a human CD4(+) lymphoblastoid cell line that was engineered to express CCR5 and is useful for the detection of weak neutralizing antibody responses against tier 2 strains of HIV-1. Here we describe the optimization and validation of the HIV-1 neutralizing antibody assay that utilizes A3R5 cells, performed in compliance with Good Clinical Laboratory Practice (GCLP) guidelines. The assay utilizes Renilla luciferase-expressing replication competent infectious molecular clones (IMC) encoding heterologous env genes from different HIV-1 clades. Key assay validation parameters tested included specificity, accuracy, precision, limit of detection and quantitation, specificity, linearity and range, and robustness. Plasma samples demonstrated higher non-specific activity than serum samples in the A3R5 assay. This assay can tolerate a wide range of virus input but is more sensitive to cell concentration. The higher sensitivity of the A3R5 assay in neutralization responses to tier 2 strains of HIV-1 makes it complementary to, but not a substitute for the TZM-bl assay. The validated A3R5 assay is employed as an endpoint immunogenicity test for vaccine-elicited neutralizing antibodies against tier 2 strains of HIV-1, and to identify correlates of protection in HIV-1 vaccine trials conducted globally. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Interdependence of initial cell density, drug concentration and exposure time revealed by real-time impedance spectroscopic cytotoxicity assay

    DEFF Research Database (Denmark)

    Caviglia, Claudia; Zor, Kinga; Canepa, Silvia

    2015-01-01

    We investigated the combined effect of the initial cell density (12 500, 35 000, 75 000, and 100 000 cells cm−2) and concentration of the anti-cancer drug doxorubicin on HeLa cells by performing timedependent cytotoxicity assays using real-time electrochemical impedance spectroscopy. A correlation...... between the rate of cell death and the initial cell seeding density was found at 2.5 μM doxorubicin concentration, whereas this was not observed at 5 or 100 μM. By sensing the changes in the cell–substrate interaction using impedance spectroscopy under static conditions, the onset of cytotoxicity...... was observed 5 h earlier than when using a standard colorimetric end-point assay (MTS) which measures changes in the mitochondrial metabolism. Furthermore, with the MTS assay no cytotoxicity was observed after 15 h of incubation with 2.5 μM doxorubicin, whereas the impedance showed at this time point cell...

  1. Single molecule microscopy in 3D cell cultures and tissues.

    Science.gov (United States)

    Lauer, Florian M; Kaemmerer, Elke; Meckel, Tobias

    2014-12-15

    From the onset of the first microscopic visualization of single fluorescent molecules in living cells at the beginning of this century, to the present, almost routine application of single molecule microscopy, the method has well-proven its ability to contribute unmatched detailed insight into the heterogeneous and dynamic molecular world life is composed of. Except for investigations on bacteria and yeast, almost the entire story of success is based on studies on adherent mammalian 2D cell cultures. However, despite this continuous progress, the technique was not able to keep pace with the move of the cell biology community to adapt 3D cell culture models for basic research, regenerative medicine, or drug development and screening. In this review, we will summarize the progress, which only recently allowed for the application of single molecule microscopy to 3D cell systems and give an overview of the technical advances that led to it. While initially posing a challenge, we finally conclude that relevant 3D cell models will become an integral part of the on-going success of single molecule microscopy. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. High affinity γPNA sandwich hybridization assay for rapid detection of short nucleic acid targets with single mismatch discrimination.

    Science.gov (United States)

    Goldman, Johnathan M; Zhang, Li Ang; Manna, Arunava; Armitage, Bruce A; Ly, Danith H; Schneider, James W

    2013-07-08

    Hybridization analysis of short DNA and RNA targets presents many challenges for detection. The commonly employed sandwich hybridization approach cannot be implemented for these short targets due to insufficient probe-target binding strengths for unmodified DNA probes. Here, we present a method capable of rapid and stable sandwich hybridization detection for 22 nucleotide DNA and RNA targets. Stable hybridization is achieved using an n-alkylated, polyethylene glycol γ-carbon modified peptide nucleic acid (γPNA) amphiphile. The γPNA's exceptionally high affinity enables stable hybridization of a second DNA-based probe to the remaining bases of the short target. Upon hybridization of both probes, an electrophoretic mobility shift is measured via interaction of the n-alkane modification on the γPNA with capillary electrophoresis running buffer containing nonionic surfactant micelles. We find that sandwich hybridization of both probes is stable under multiple binding configurations and demonstrate single base mismatch discrimination. The binding strength of both probes is also stabilized via coaxial stacking on adjacent hybridization to targets. We conclude with a discussion on the implementation of the proposed sandwich hybridization assay as a high-throughput microRNA detection method.

  3. An improved enzyme-linked immunosorbent assay for whole-cell determination of methanogens in samples from anaerobic reactors

    DEFF Research Database (Denmark)

    Sørensen, A.H.; Ahring, B.K.

    1997-01-01

    An enzyme-linked immunosorbent assay was developed for the detection of whole cells of methanogens in samples from anaerobic continuously stirred tank digesters treating slurries of solid waste. The assay was found to allow for quantitative analysis of the most important groups of methanogens...... in samples from anaerobic digesters in a reproducible manner. Polyclonal antisera against eight strains of methanogens were employed in the test, The specificities of the antisera were increased by adsorption with cross-reacting cells. The reproducibility of the assay depended on the use of high......-quality microtiter plates and the addition of dilute hydrochloric acid to the samples. In an experiment on different digester samples, the test demonstrated a unique pattern of different methanogenic strains present in each sample. The limited preparatory work required for the assay and the simple assay design make...

  4. A photoacoustic technique to measure the properties of single cells

    Science.gov (United States)

    Strohm, Eric M.; Berndl, Elizabeth S. L.; Kolios, Michael C.

    2013-03-01

    We demonstrate a new technique to non-invasively determine the diameter and sound speed of single cells using a combined ultrasonic and photoacoustic technique. Two cell lines, B16-F1 melanoma cells and MCF7 breast cancer cells were examined using this technique. Using a 200 MHz transducer, the ultrasound backscatter from a single cell in suspension was recorded. Immediately following, the cell was irradiated with a 532 nm laser and the resulting photoacoustic wave recorded by the same transducer. The melanoma cells contain optically absorbing melanin particles, which facilitated photoacoustic wave generation. MCF7 cells have negligible optical absorption at 532 nm; the cells were permeabilized and stained with trypan blue prior to measurements. The measured ultrasound and photoacoustic power spectra were compared to theoretical equations with the cell diameter and sound speed as variables (Anderson scattering model for ultrasound, and a thermoelastic expansion model for photoacoustics). The diameter and sound speed were extracted from the models where the spectral shape matched the measured signals. However the photoacoustic spectrum for the melanoma cell did not match theory, which is likely because melanin particles are located around the cytoplasm, and not within the nucleus. Therefore a photoacoustic finite element model of a cell was developed where the central region was not used to generate a photoacoustic wave. The resulting power spectrum was in better agreement with the measured signal than the thermoelastic expansion model. The MCF7 cell diameter obtained using the spectral matching method was 17.5 μm, similar to the optical measurement of 16 μm, while the melanoma cell diameter obtained was 22 μm, similar to the optical measurement of 21 μm. The sound speed measured from the MCF7 and melanoma cell was 1573 and 1560 m/s, respectively, which is within acceptable values that have been published in literature.

  5. VNAR single-domain antibodies specific for BAFF inhibit B cell development by molecular mimicry.

    Science.gov (United States)

    Häsler, Julien; Flajnik, Martin F; Williams, Gareth; Walsh, Frank S; Rutkowski, J Lynn

    2016-07-01

    B cell-activating factor (BAFF) plays a dominant role in the B cell homeostasis. However, excessive BAFF promotes the development of autoreactive B-cells and several antibodies have been developed to block its activity. Bispecific antibodies with added functionality represent the next wave of biologics that may be more effective in the treatment of complex autoimmune disease. The single variable domain from the immunoglobulin new antigen receptor (VNAR) is one of the smallest antibody recognition units that could be combined with monospecific antibodies to develop bispecific agents. We isolated a panel of BAFF-binding VNARs with low nM potency from a semi-synthetic phage display library and examined their functional activity. The anti-BAFF VNARs blocked the binding of BAFF to all three of its receptors (BR3, TACI and BCMA) and the presence of the conserved DXL receptor motif found in the CDR3 regions suggests molecular mimicry as the mechanism of antagonism. One clone was formatted as an Fc fusion for functional testing and it was found to inhibit both mouse and human BAFF with equal potency ex vivo in a splenocyte proliferation assay. In mice, subchronic administration reduced the number of immature and transitional intermediates B cells and mature B cell subsets. These results indicate that VNAR single domain antibodies function as selective B-cell inhibitors and offer an alternative molecular format for targeting B-cell disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Exploring single electrode reactions in polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, H.; Wokaun, A.; Scherer, G.G. [Paul Scherrer Institute, Electrochemistry Laboratory, 5232 Villigen (Switzerland)

    2007-01-20

    Utilising a pseudo-reference electrode in polymer electrolyte fuel cells allows for the separation of anodic and cathodic contributions to the entire cell impedance. Modelling the impedance responses by using equivalent circuits inhibits the investigation of kinetic parameters of the basic electrochemical reactions, which take place at single electrode-electrolyte interfaces. Therefore, we evaluate single electrode impedance measurements by a kinetic model, which is based on specific reaction pathways, either for the oxygen reduction reaction (ORR) or the hydrogen oxidation reaction (HOR). As a consequence, it is possible to obtain kinetic parameters for the specific reaction of interest. Furthermore, the information gained from the single electrode impedance measurements and the kinetic model can give insight into single reactions steps. In particular, the ORR has to include a chemical step in the reaction pathway. (author)

  7. Micro-arrayed human embryonic stem cells-derived cardiomyocytes for in vitro functional assay.

    Directory of Open Access Journals (Sweden)

    Elena Serena

    Full Text Available INTRODUCTION: The heart is one of the least regenerative organs in the body and any major insult can result in a significant loss of heart cells. The development of an in vitro-based cardiac tissue could be of paramount importance for many aspects of the cardiology research. In this context, we developed an in vitro assay based on human cardiomyocytes (hCMs and ad hoc micro-technologies, suitable for several applications: from pharmacological analysis to physio-phatological studies on transplantable hCMs. We focused on the development of an assay able to analyze not only hCMs viability, but also their functionality. METHODS: hCMs were cultured onto a poly-acrylamide hydrogel with tunable tissue-like mechanical properties and organized through micropatterning in a 20×20 array. Arrayed hCMs were characterized by immunofluorescence, GAP-FRAP analyses and live and dead assay. Their functionality was evaluated monitoring the excitation-contraction coupling. RESULTS: Micropatterned hCMs maintained the expression of the major cardiac markers (cTnT, cTnI, Cx43, Nkx2.5, α-actinin and functional properties. The spontaneous contraction frequency was (0.83±0.2 Hz, while exogenous electrical stimulation lead to an increase up to 2 Hz. As proof of concept that our device can be used for screening the effects of pathological conditions, hCMs were exposed to increasing levels of H(2O(2. Remarkably, hCMs viability was not compromised with exposure to 0.1 mM H(2O(2, but hCMs contractility was dramatically suppressed. As proof of concept, we also developed a microfluidic platform to selectively treat areas of the cell array, in the perspective of performing multi-parametric assay. CONCLUSIONS: Such system could be a useful tool for testing the effects of multiple conditions on an in vitro cell model representative of human heart physiology, thus potentially helping the processes of therapy and drug development.

  8. Magnetophoretic circuits for digital control of single particles and cells

    Science.gov (United States)

    Lim, Byeonghwa; Reddy, Venu; Hu, Xinghao; Kim, Kunwoo; Jadhav, Mital; Abedini-Nassab, Roozbeh; Noh, Young-Woock; Lim, Yong Taik; Yellen, Benjamin B.; Kim, Cheolgi

    2014-05-01

    The ability to manipulate small fluid droplets, colloidal particles and single cells with the precision and parallelization of modern-day computer hardware has profound applications for biochemical detection, gene sequencing, chemical synthesis and highly parallel analysis of single cells. Drawing inspiration from general circuit theory and magnetic bubble technology, here we demonstrate a class of integrated circuits for executing sequential and parallel, timed operations on an ensemble of single particles and cells. The integrated circuits are constructed from lithographically defined, overlaid patterns of magnetic film and current lines. The magnetic patterns passively control particles similar to electrical conductors, diodes and capacitors. The current lines actively switch particles between different tracks similar to gated electrical transistors. When combined into arrays and driven by a rotating magnetic field clock, these integrated circuits have general multiplexing properties and enable the precise control of magnetizable objects.

  9. The Use of Evolutionary Approaches to Understand Single Cell Genomes

    Directory of Open Access Journals (Sweden)

    Haiwei eLuo

    2015-03-01

    Full Text Available The vast majority of environmental bacteria and archaea remain uncultivated, yet their genome sequences are rapidly becoming available through single cell sequencing technologies. Reconstructing metabolism is one common way to make use of genome sequences of ecologically important bacteria, but molecular evolutionary analysis is another approach that, while currently underused, can reveal important insights into the function of these uncultivated microbes in nature. Because genome sequences from single cells are often incomplete, metabolic reconstruction based on genome content can be compromised. However, this problem does not necessarily impede the use of phylogenomic and population genomic approaches that are based on patterns of polymorphisms and substitutions at nucleotide and amino acid sites. These approaches explore how various evolutionary forces act to assemble genetic diversity within and between lineages. In this mini-review, I present examples illustrating the benefits of analyzing single cell genomes using evolutionary approaches.

  10. Antiproliferative and Apoptotic Effects of a Specific Antiprostate Stem Cell Single Chain Antibody on Human Prostate Cancer Cells

    Directory of Open Access Journals (Sweden)

    Foroogh Nejatollahi

    2013-01-01

    Full Text Available Prostate stem cell antigen (PSCA is a highly glycosylated cell surface protein which is overexpressed in several malignancies including prostate, pancreas, and urinary bladder cancers. Tumor suppression has been reported by anti-PSCA antibody. Small and high affinity single chain antibodies (scFv have been introduced as effective agents for cancer immunotargeting approaches. In the present study, we used a phage antibody display library of scFv and selected two antibodies against two immunodominant epitopes of PSCA by panning process. The reactivity of the scFvs for the corresponding epitopes was determined by phage ELISA. The binding specificity of antibodies to PSCA-expressing prostate cancer cell line, DU-145, was analyzed by flow cytometry. The antiproliferative and apoptotic induction effects were evaluated by MTT and Annexin-V assays, respectively. Results represented functional scFv C5-II which could bind specifically to DU-145 cells and significantly inhibited the proliferation of these cells (61% with no effect on PSCA-negative cells. The antibody also induced apoptosis in the PSCA expressing cells. The percentage of the apoptotic cells after 24 hrs of exposure to 500 scFv/cell was 33.80%. These results demonstrate that the functional anti-PSCA scFv C5-II has the potential to be considered as a new agent for targeted therapy of prostate cancer.

  11. Assay of anticancer drugs in tissue culture: cell cultures of biopsies from human astrocytoma.

    Science.gov (United States)

    Morgan, D; Freshney, R I; Darling, J L; Thomas, D G; Celik, F

    1983-02-01

    A method has been developed for measuring the drug sensitivity of human gliomas in short-term culture, using scintillation counting or autofluorography. Cell cultures prepared from malignant astrocytomas were treated with anticancer drugs whilst in exponential growth in microtitration plates. After drug treatment and a recovery period, residual viability was measured by [3H] leucine incorporation followed by scintillation counting or by [35S] methionine incorporation and autofluorography in situ. In 5 glioma cell lines tested against 6 drugs, the microtitration method correlated well with monolayer cloning. Although replicate samples of the same tumour showed little variation in chemosensitivity, there was marked variation between the chemosensitivities of cultures derived from the tumours of different patients. However, as variability between replicates was apparent during drug exposure or shortly after, it is important to allow the assay to run as long as possible after drug removal. It is hoped that this assay may provide the basis of a method for the prediction of in vivo chemosensitivity or the screening of potential chemotherapeutic drugs.

  12. A Kinetic Aggregation Assay Enabling Selective and Sensitive Aβ Amyloid Quantification in Cells and Tissues

    Science.gov (United States)

    Du, Deguo; Murray, Amber N.; Cohen, Ehud; Kim, Hyun-Eui; Simkovsky, Ryan; Dillin, Andrew; Kelly, Jeffery W.

    2011-01-01

    The process of amyloid-β (Aβ) fibril formation is genetically and pathologically linked to Alzheimer's disease (AD). Thus, a selective and sensitive method for the quantification of Aβ amyloid fibrils in complex biological samples enables a variety of hypotheses to be tested. Herein we report the basis for a quantitative in vitro kinetic aggregation assay that detects seeding-competent Aβ aggregates in mammalian cell culture media, in Caenorhabditis elegans lysate and in mouse brain homogenate. Sonicated, proteinase K treated Aβ-fibril-containing tissue homogenates or cell culture media were added to an initially monomeric Aβ1–40 reporter peptide to seed an in vitro nucleated aggregation reaction. The reduction in the half time (t50) of the amyloid growth phase is proportional to the quantity of seeding-competent Aβ aggregates present in the biological sample. An ion exchange resin amyloid isolation strategy from complex biological samples is demonstrated as an alternative to improve the sensitivity and linearity of the kinetic aggregation assay. PMID:21268584

  13. Radiomodifying effect of resveratrol in human rhabdomyosarcoma (RD) cell culture applying the comet assay

    International Nuclear Information System (INIS)

    Magalhaes, Vanessa D.; Rogero, Sizue O.; Vieira, Daniel P.; Okazaki, Kayo; Rogero, Jose R.; Cruz, Aurea S.

    2013-01-01

    Cancer is considered a worldwide public health problem. Resveratrol is a defense polyphenol, synthesized naturally by a wide variety of plants according to response of ultraviolet radiation (UV) exposition or according to mechanical stress resulting of pathogens or chemical and physical agents. In vines this substance is found in elevated concentration. Thus, resveratrol is present in grape juice and wines, especially red wine. Red wines are the best dietary source of resveratrol.The protective effects performed by resveratrol during the process of cell damage, produced by oxidative effects of free radicals, are anti-inflammatory, anti-platelet and anti-carcinogenic activity, prevent or inhibit degenerative diseases, decrease incidence of cardiovascular diseases. Moreover, resveratrol is considered as a cell radioprotector. On the other hand, in some elevated concentrations resveratrol is considered as a radiosensitizing compound. The aim of this work was study in vitro the radiomodifying effect of resveratrol in human rhabdomyosarcoma (RD) cells applying the comet assay to evaluate the cellular damage and its repair capacity. In this study RD cells culture was irradiated by gamma radiation at 50 Gy and 100 Gy doses and the used resveratrol concentrations was from 15 μM to 60 μM. The protective and radioprotective effects were observed at 15 μM and 30 μM resveratrol concentrations. The resveratrol concentration of 60 μM showed cytotoxic effect to RD tumor cells and with gamma radiation presence this concentration showed no statistically significant radiosensitizing effects. (author)

  14. Radiomodifying effect of resveratrol in human rhabdomyosarcoma (RD) cell culture applying the comet assay

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes, Vanessa D.; Rogero, Sizue O.; Vieira, Daniel P.; Okazaki, Kayo; Rogero, Jose R., E-mail: van.biologa@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Cruz, Aurea S., E-mail: aurcruz@ial.sp.gov.br [Instituto Adolfo Lutz (IAL-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Cancer is considered a worldwide public health problem. Resveratrol is a defense polyphenol, synthesized naturally by a wide variety of plants according to response of ultraviolet radiation (UV) exposition or according to mechanical stress resulting of pathogens or chemical and physical agents. In vines this substance is found in elevated concentration. Thus, resveratrol is present in grape juice and wines, especially red wine. Red wines are the best dietary source of resveratrol.The protective effects performed by resveratrol during the process of cell damage, produced by oxidative effects of free radicals, are anti-inflammatory, anti-platelet and anti-carcinogenic activity, prevent or inhibit degenerative diseases, decrease incidence of cardiovascular diseases. Moreover, resveratrol is considered as a cell radioprotector. On the other hand, in some elevated concentrations resveratrol is considered as a radiosensitizing compound. The aim of this work was study in vitro the radiomodifying effect of resveratrol in human rhabdomyosarcoma (RD) cells applying the comet assay to evaluate the cellular damage and its repair capacity. In this study RD cells culture was irradiated by gamma radiation at 50 Gy and 100 Gy doses and the used resveratrol concentrations was from 15 μM to 60 μM. The protective and radioprotective effects were observed at 15 μM and 30 μM resveratrol concentrations. The resveratrol concentration of 60 μM showed cytotoxic effect to RD tumor cells and with gamma radiation presence this concentration showed no statistically significant radiosensitizing effects. (author)

  15. Selection of internal references for qRT-PCR assays of human hepatocellular carcinoma cell lines.

    Science.gov (United States)

    Liu, Yang; Qin, Zhaoyu; Cai, Lili; Zou, Lili; Zhao, Jing; Zhong, Fan

    2017-12-22

    Selecting internal references is important for normalizing the loading quantity of samples in quantitative reverse-transcription PCR (qRT-PCR). In the present study, a systematic evaluation of reference genes among nine hepatocellular carcinoma (HCC) cell lines was conducted. After screening the microarray assay data of ten HCC cell lines, 19 candidate reference genes were preselected and then evaluated by qRT-PCR, together with ACTB, GAPDH, HPRT1 and TUBB The expression evenness of these candidate genes was evaluated using RefFinder. The stabilities of the reference genes were further evaluated under different experimental perturbations in Huh-7 and MHCC-97L, and the applicability of the reference genes was assessed by measuring the mRNA expression of CCND1, CCND3, CDK4 and CDK6 under sorafenib treatment in Huh-7. Results showed that TFG and SFRS4 are among the most reliable reference genes, and ACTB ranks third and acts quite well as a classical choice, whereas GAPDH, HPRT1 and TUBB are not proper reference genes in qRT-PCR assays among the HCC cell lines. SFRS4, YWHAB, SFRS4 and CNPY3 are the most stable reference genes of the MHCC-97L under the perturbations of chemotherapy, oxidative stress, starvation and hypoxia respectively, whereas YWHAB is the most stable one of Huh-7 under all perturbations. GAPDH is recommended as a reference gene under chemotherapy perturbations. YWHAB and UBE2B, TMED2 and TSFM , and GAPDH and TSFM are the two best reference genes under oxidative stress, starvation and hypoxia perturbations respectively. TSFM is stable in both cell lines across all the perturbations. © 2017 The Author(s).

  16. Effects of Metalloporphyrins on Heme Oxygenase-1 Transcription: Correlative Cell Culture Assays Guide in Vivo Imaging

    Directory of Open Access Journals (Sweden)

    Monica Hajdena-Dawson

    2003-07-01

    Full Text Available Heme oxygenase (HO is the rate-limiting step in the heme degradation pathway and is a potential target for the control, or prevention, of pathologic jaundice in neonates. Metalloporphyrins (Mps, a diverse set of synthetic derivatives of heme, can competitively inhibit the HO enzymes. However, certain Mps are phototoxic and some increase transcription of HO-1, the inducible HO isozyme. Therefore, effective development of this class of compounds as therapeutics for treating pathologic jaundice will require rapid and integrated biological screens to identify the most efficacious and safe Mps. To study the safety of these compounds, we assessed their cytotoxic effects and measured luciferase activity by bioluminescent imaging (BLI as an index of HO-1 transcription, first in live cell cultures and then in living transgenic reporter mice. A total of 12 Mps were first evaluated in the correlative cell culture assay. Based on results from this study, 2 Mps, zinc protoporphyrin (ZnPP and zinc bis glycol porphyrin (ZnBG, were selected for further studies in the live animal model. In vitro BLI showed ZnPP to be a strong inducer of HO-1 transcription in comparison to ZnBG, which showed minimal induction. Cytotoxicity studies revealed that ZnPP was phototoxic, whereas ZnBG had no effect on cell viability. In vivo BLI showed that both ZnPP and ZnBG had minimal effects on the levels of HO-1 transcription in the animals. Furthermore, serum enzyme assays indicated that neither caused detectable liver toxicity. These findings, and especially those with ZnBG, support the use of selected Mps as therapies for pathologic jaundice. Coupling the high throughput advantage of cell culture with the capability of imaging for whole-body temporal analyses could accelerate and refine the preclinical phases of drug development. Thus, this study serves as a model for understanding the effects of specific compounds in relation to defined targets using an integrated approach.

  17. Microfluidic cell culture chip with multiplexed medium delivery and efficient cell/scaffold loading mechanisms for high-throughput perfusion 3-dimensional cell culture-based assays.

    Science.gov (United States)

    Huang, Song-Bin; Wu, Min-Hsien; Wang, Shih-Siou; Lee, Gwo-Bin

    2011-06-01

    This study reports a microfluidic cell culture chip consisting of 48 microbioreactors for high-throughput perfusion 3-dimensional (3-D) cell culture-based assays. Its advantages include the capability for multiplexed and backflow-free medium delivery, and both efficient and high-throughput micro-scale, 3-D cell culture construct loading. In this work, the microfluidic cell culture chip is fabricated using two major processes, specifically, a computer-numerical-controlled (CNC) mold machining process and a polydimethylsiloxane (PDMS) replication process. The chip is composed of micropumps, microbioreactors, connecting microchannels and a cell/agarose scaffold loading mechanism. The performance of the new pneumatic micropumps and the cell/agarose scaffold loading mechanism has been experimentally evaluated. The experimental results show that this proposed multiplexed medium-pumping design is able to provide a uniform pumping rate ranging from 1.5 to 298.3 μl hr(-1) without any fluid backflow and the resultant medium contamination. In addition, the simple cell/agarose loading method has been proven to be able to load the 3-D cell culture construct uniformly and efficiently in all 48 microbioreactors investigated. Furthermore, a micro-scale, perfusion, 3-D cell culture-based assay has been successfully demonstrated using this proposed cell culture chip. The experimental results are also compared to a similar evaluation using a conventional static 3-D cell culture with a larger scale culture. It is concluded that the choice of a cell culture format can influence assay results. As a whole, because of the inherent advantages of a miniaturized perfusion 3-D cell culture assay, the cell culture chip not only can provide a stable, well-defined and more biologically-meaningful culture environment, but it also features a low consumption of research resources. Moreover, due to the integrated medium pumping mechanism and the simple cell/agarose loading method, this chip is

  18. A rapid and robust assay for detection of S-phase cell cycle progression in plant cells and tissues by using ethynyl deoxyuridine

    Directory of Open Access Journals (Sweden)

    Horváth Gábor V

    2010-01-01

    Full Text Available Abstract Background Progress in plant cell cycle research is highly dependent on reliable methods for detection of cells replicating DNA. Frequency of S-phase cells (cells in DNA synthesis phase is a basic parameter in studies on the control of cell division cycle and the developmental events of plant cells. Here we extend the microscopy and flow cytometry applications of the recently developed EdU (5-ethynyl-2'-deoxyuridine-based S-phase assay to various plant species and tissues. We demonstrate that the presented protocols insure the improved preservation of cell and tissue structure and allow significant reduction in assay duration. In comparison with the frequently used detection of bromodeoxyuridine (BrdU and tritiated-thymidine incorporation, this new methodology offers several advantages as we discuss here. Results Applications of EdU-based S-phase assay in microscopy and flow cytometry are presented by using cultured cells of alfalfa, Arabidopsis, grape, maize, rice and tobacco. We present the advantages of EdU assay as compared to BrdU-based replication assay and demonstrate that EdU assay -which does not require plant cell wall digestion or DNA denaturation steps, offers reduced assay duration and better preservation of cellular, nuclear and chromosomal morphologies. We have also shown that fast and efficient EdU assay can also be an efficient tool for dual parameter flow cytometry analysis and for quantitative assessment of replication in thick root samples of rice. Conclusions In plant cell cycle studies, EdU-based S-phase detection offers a superior alternative to the existing S-phase assays. EdU method is reliable, versatile, fast, simple and non-radioactive and it can be readily applied to many different plant systems.

  19. Femtosecond laser fabricated microfluorescence-activated cell sorter for single cell recovery

    Science.gov (United States)

    Bragheri, F.; Paiè, P.; Nava, G.; Yang, T.; Minzioni, P.; Martinez Vazquez, R.; Bellini, N.; Ramponi, R.; Cristiani, I.; Osellame, R.

    2014-03-01

    Manipulation, sorting and recovering of specific live cells from samples containing less than a few thousand cells is becoming a major hurdle in rare cell exploration such as stem cell research or cell based diagnostics. Moreover the possibility of recovering single specific cells for culturing and further analysis would be of great impact in many biological fields ranging from regenerative medicine to cancer therapy. In recent years considerable effort has been devoted to the development of integrated and low-cost optofluidic devices able to handle single cells, which usually rely on microfluidic circuits that guarantee a controlled flow of the cells. Among the different microfabrication technologies, femtosecond laser micromachining (FLM) is ideally suited for this purpose as it provides the integration of both microfluidic and optical functions on the same glass chip leading to monolithic, robust and portable devices. Here a new optofluidic device is presented, which is capable of sorting and recovering of single cells, through optical forces, on the basis of their fluorescence and. Both fluorescence detection and single cell sorting functions are integrated in the microfluidic chip by FLM. The device, which is specifically designed to operate with a limited amount of cells but with a very high selectivity, is fabricated by a two-step process that includes femtosecond laser irradiation followed by chemical etching. The capability of the device to act as a micro fluorescence-activated cell sorter has been tested on polystyrene beads and on tumor cells and the results on the single live cell recovery are reported.

  20. Paired single cell co-culture microenvironments isolated by two-phase flow with continuous nutrient renewal.

    Science.gov (United States)

    Chen, Yu-Chih; Cheng, Yu-Heng; Kim, Hong Sun; Ingram, Patrick N; Nor, Jacques E; Yoon, Euisik

    2014-08-21

    Cancer-stromal cell interactions are a critical process in tumorigenesis. Conventional dish-based assays, which simply mix two cell types, have limitations in three aspects: 1) limited control of the cell microenvironment; 2) inability to study cell behavior in a single-cell manner; and 3) have difficulties in characterizing single cell behavior within a highly heterogeneous cell population (e.g. tumor). An innovative use of microfluidic technology is for improving the spatial resolution for single cell assays. However, it is challenging to isolate the paired interacting cells while maintaining nutrient renewal. In this work, two-phase flow was used as a simple isolation method, separating the microenvironment of each individual chamber. As nutrients in an isolated chamber are consumed by cells, media exchange is required. To connect the cell culture chamber to the media exchange layer, we demonstrated a 3D microsystem integration technique using vertical connections fabricated by deep reactive-ion etching (DRIE). Compared to previous approaches, the presented process allows area reduction of vertical connections by an order of magnitude, enabling compact 3D integration. A semi-permeable membrane was sandwiched between the cell culture layer and the media exchange layer. The selectivity of the semi-permeable membrane results in the retention of the signaling proteins within the chamber while allowing free diffusion of nutrients (e.g., glucose and amino acids). Thus, paracrine signals are accumulated inside the chamber without cross-talk between cells in other chambers. Utilizing these innovations, we co-cultured UM-SCC-1 (head and neck squamous cell carcinoma) cells and endothelial cells to simulate tumor proliferation enhancement in the vascular endothelial niche.

  1. Development and assessment of multiplex high resolution melting assay as a tool for rapid single-tube identification of five Brucella species.

    Science.gov (United States)

    Gopaul, Krishna K; Sells, Jessica; Lee, Robin; Beckstrom-Sternberg, Stephen M; Foster, Jeffrey T; Whatmore, Adrian M

    2014-12-11

    The zoonosis brucellosis causes economically significant reproductive problems in livestock and potentially debilitating disease of humans. Although the causative agent, organisms from the genus Brucella, can be differentiated into a number of species based on phenotypic characteristics, there are also significant differences in genotype that are concordant with individual species. This paper describes the development of a five target multiplex assay to identify five terrestrial Brucella species using real-time polymerase chain reaction (PCR) and subsequent high resolution melt curve analysis. This technology offers a robust and cost effective alternative to previously described hydrolysis-probe Single Nucleotide Polymorphism (SNP)-based species defining assays. Through the use of Brucella whole genome sequencing five species defining SNPs were identified. Individual HRM assays were developed to these target these changes and, following optimisation of primer concentrations, it was possible to multiplex all five assays in a single tube. In a validation exercise using a panel of 135 Brucella strains of terrestrial and marine origin, it was possible to distinguish the five target species from the other species within this panel. The HRM multiplex offers a number of diagnostic advantages over previously described SNP-based typing approaches. Further, and uniquely for HRM, the successful multiplexing of five assays in a single tube allowing differentiation of five Brucella species in the diagnostic laboratory in a cost-effective and timely manner is described. However there are possible limitations to using this platform on DNA extractions direct from clinical material.

  2. Single-cell duplex RT-LATE-PCR reveals Oct4 and Xist RNA gradients in 8-cell embryos

    Directory of Open Access Journals (Sweden)

    Hartung Odelya

    2007-12-01

    Full Text Available Abstract Background The formation of two distinctive cell lineages in preimplantation mouse embryos is characterized by differential gene expression. The cells of the inner cell mass are pluripotent and express high levels of Oct4 mRNA, which is down-regulated in the surrounding trophectoderm. In contrast, the trophectoderm of female embryos contains Xist mRNA, which is absent from cells of the inner mass. Prior to blastocyst formation, all blastomeres of female embryos still express both of these RNAs. We, thus, postulated that simultaneous quantification of Oct4 and Xist transcripts in individual blastomeres at the 8-cell stage could be informative as to their subsequent fate. Testing this hypothesis, however, presented numerous technical challenges. We overcame these difficulties by combining PurAmp, a single-tube method for RNA preparation and quantification, with LATE-PCR, an advanced form of asymmetric PCR. Results We constructed a duplex RT-LATE-PCR assay for real-time measurement of Oct4 and Xist templates and confirmed its specificity and quantitative accuracy with different methods. We then undertook analysis of sets of blastomeres isolated from embryos at the 8-cell stage. At this stage, all cells in the embryo are still pluripotent and morphologically equivalent. Our results demonstrate, however, that both Oct4 and Xist RNA levels vary in individual blastomeres comprising the same embryo, with some cells having particularly elevated levels of either transcript. Analysis of multiple embryos also shows that Xist and Oct4 expression levels are not correlated at the 8-cell stage, although transcription of both genes is up-regulated at this time in development. In addition, comparison of data from males and females allowed us to determine that the efficiency of the Oct4/Xist assay is unaffected by sex-related differences in gene expression. Conclusion This paper describes the first example of multiplex RT-LATE-PCR and its utility, when

  3. Development of a flow cytometric assay to quantify lymphocyte adhesion to cytokine-stimulated human endothelial and biliary epithelial cells.

    Science.gov (United States)

    Korlipara, L V; Leon, M P; Rix, D A; Douglas, M S; Gibbs, P; Bassendine, M F; Kirby, J A

    1996-05-27

    The adhesive interaction between T lymphocytes and parenchymal cells is of importance for many processes of the cellular immune response. This adhesion is regulated by the activation status of the T cell and by cytokines in the microenvironment which can alter adhesion molecule expression by endothelial and epithelial cells. In this study results from an isotopic adhesion assay were compared with those from a flow cytometric assay in order to determine which was most appropriate for the investigation of lymphocyte adhesion to human umbilical vein endothelial cells (HUVEC) and intrahepatic biliary epithelial cells (HIBEC). Treatment of both these cell types with the proinflammatory cytokines interferon-gamma (IFN-gamma) or tumour necrosis factor-alpha (TNF-alpha) significantly upregulated expression of intercellular adhesion molecule-1 (ICAM-1). Treatment with TNF-alpha also induced endothelial cells to express vascular cell adhesion molecule-1 (VCAM-1). The isotopic assay demonstrated increased adhesion of lymphoblasts to HUVEC which had been stimulated with cytokines for 15 h but failed to detect major changes in adhesion following 72 h of cytokine treatment of HUVEC or HIBEC. However, the flow cytometric assay reproducibly demonstrated increased adhesion following cytokine treatment for both these time periods; these increases corresponded with the changes in adhesion molecule expression by cytokine-stimulated HUVEC and HIBEC targets. The differences in apparent adhesion measured by the two assays after cytokine stimulation for 72 h may be explained by cytokine-induced changes in the morphology and confluency of cultured cells. Results of the isotopic assay are proportional to the total number of lymphoid cells bound by the cultured target cells and will be distorted by changes in effective target cell area. The flow cytometric assay measures the mean number of lymphoid cells bound by each target cell and is independent of the total binding area. It is concluded

  4. Single-cell tracking reveals antibiotic-induced changes in mycobacterial energy metabolism.

    Science.gov (United States)

    Maglica, Željka; Özdemir, Emre; McKinney, John D

    2015-02-17

    method described here for single-cell tracking of intracellular ATP in live bacteria has many advantages compared to conventional ensemble-averaged assays. It provides a continuous real-time readout of bacterial ATP content, cell vitality, and antimicrobial mechanism of action with high temporal resolution at the single-cell level. In combination with high-throughput microfluidic devices and automated microscopy, this method also has the potential to serve as a novel screening tool in antimicrobial drug discovery. Copyright © 2015 Maglica et al.

  5. In vitro effects of piracetam on the radiosensitivity of hypoxic cells (adaptation of MTT assay to hypoxic conditions)

    International Nuclear Information System (INIS)

    Gheuens, E.E.O.; Bruijn, E.A. de; Van der Heyden, S.; Van Oosterom, A.T.; Lagarde, P.; Pooter, C.M.J. de; Chomy, F.

    1995-01-01

    This paper describes the adaptation of the MTT assay to hypoxic conditions in order to test the in vitro effect of piracetam on hypoxic cells and particularly on the radiosensitivity of hypoxic cells since this drug has shown clinical effect on acute and chronic hypoxia. The V79 cell line was selected by reference to preliminary hypoxic experiments using clonogenic assay and euoxic experiments using clonogenic and MTT assays. Cell growth and survival in our hypoxic conditions were assessed using MTT assay with an enclosure and special 48-well plates both made of glass. Growth curves on glass plates after 1-hour exposure to nitrogen versus air were comparable, so there is no bias effect due to gas composition. Survival curves using MTT versus reference clonogenic assay were comparable after radiation exposure in eu- and hypoxic conditions, and confirm the validity of our original technique for creating hypoxia. The Oxygen Enhancement Ratio was of about 3 for 1-hour hypoxic exposure. Piracetam gave no cytotoxic effect up to 10 mM of piracetam. Growth curves after continuous drug exposure and 1-hour euoxic versus hypoxic exposure gave no cytotoxic effect up to 10 mM of piracetam. Survival curves after continuous drug exposure to 10 mM of piracetam gave no significant effect on the radiosensitivity of hypoxic V79 cells using MTT or clonogenic assay. (author). 32 refs., 6 figs

  6. Toward single cell traction microscopy within 3D collagen matrices

    International Nuclear Information System (INIS)

    Hall, Matthew S.; Long, Rong; Feng, Xinzeng; Huang, YuLing; Hui, Chung-Yuen; Wu, Mingming

    2013-01-01

    Mechanical interaction between the cell and its extracellular matrix (ECM) regulates cellular behaviors, including proliferation, differentiation, adhesion, and migration. Cells require the three-dimensional (3D) architectural support of the ECM to perform physiologically realistic functions. However, current understanding of cell–ECM and cell–cell mechanical interactions is largely derived from 2D cell traction force microscopy, in which cells are cultured on a flat substrate. 3D cell traction microscopy is emerging for mapping traction fields of single animal cells embedded in either synthetic or natively derived fibrous gels. We discuss here the development of 3D cell traction microscopy, its current limitations, and perspectives on the future of this technology. Emphasis is placed on strategies for applying 3D cell traction microscopy to individual tumor cell migration within collagen gels. - Highlights: • Review of the current state of the art in 3D cell traction force microscopy. • Bulk and micro-characterization of remodelable fibrous collagen gels. • Strategies for performing 3D cell traction microscopy within collagen gels

  7. V79 cell survival after a single lithium ion nuclear traversal

    International Nuclear Information System (INIS)

    Pinto, M.; Buonanno, M.; Campajola, L.; Durante, M.; Grossi, G.; Publiese, G.; Scampoli, P.; Gialanella, G.; Manti, L.

    2003-01-01

    Full text: Biological studies on the effects of low doses of densely ionising radiation are highly influenced by the stochastic character of the energy deposition events. For several end-points, including clonogenic survival, to follow-up individual cells that have undergone an exactly determined number of charged particle traversals is highly desirable. While RBE-LET curves have been measured after conventional 'broad beam' irradiation with several ions of varying energies, the probability of cell survival after a single charged particle traversal has only been determined for accelerated protons and alpha particles, whereas the ability of single particle traversals at higher LET to cause clonogenic death is yet unknown. Recently, low dose studies have also shown phenomena of high interest, such as the hypersensitivity/induced radioresistance(HS/IRR) adaptive responses. However, for particles of high LET, even a single nuclear traversal may deliver an average dose to a single cell that may be beyond the dose region of the HS/IRR response. We ave set up an experimental apparatus for the determination of the inactivation cross section after an exactly known number of accelerated Lithium ions traversals (210 keV/micron when hitting the cell surface). Using a bio-stack approach (Pugliese et al, IJRB Oct;72(4):397-407 1997) LR115 thin nuclear track detectors have been employed for the direct visualisation of Lithium ion traversals in V79 cells nuclei that are labeled with Hoechst 33258. A computer software has been designed and implemented to control micro-meter movements of a motorised Marzhauser stage, mounted on a fluorescent microscope, for the acquisition of individual attached cell coordinates, type of traversal, as well as for re-visiting the registered coordinates for analysis of survivors. The V79 cell survival experiment after exactly known numbers of Lithium ions traversals is in progress, along with a classical 'broad beam' survival assay

  8. Micromechanical and surface adhesive properties of single saccharomyces cerevisiae cells

    Science.gov (United States)

    Farzi, Bahman; Cetinkaya, Cetin

    2017-09-01

    The adhesion and mechanical properties of a biological cell (e.g. cell membrane elasticity and adhesiveness) are often strong indicators for the state of its health. Many existing techniques for determining mechanical properties of cells require direct physical contact with a single cell or a group of cells. Physical contact with the cell can trigger complex mechanotransduction mechanisms, leading to cellular responses, and consequently interfering with measurement accuracy. In the current work, based on ultrasonic excitation and interferometric (optical) motion detection, a non-contact method for characterizing the adhesion and mechanical properties of single cells is presented. It is experimentally demonstrated that the rocking (rigid body) motion and internal vibrational resonance frequencies of a single saccharomyces cerevisiae (SC) (baker’s yeast) cell can be acquired with the current approach, and the Young’s modulus and surface tension of the cell membrane as well as surface adhesion energy can be extracted from the values of these acquired resonance frequencies. The detected resonance frequency ranges for single SC cells include a rocking (rigid body) frequency of 330  ±  70 kHz and two breathing resonance frequencies of 1.53  ±  0.12 and 2.02  ±  0.31 MHz. Based on these values, the average work-of-adhesion of SC cells on a silicon substrate in aqueous medium is extracted, for the first time, as WASC-Si=16.2+/- 3.8 mJ {{m}-2} . Similarly, the surface tension and the Young’s modulus of the SC cell wall are predicted as {{σ }SC}=0.16+/- 0.02 N {{m}-1} and {{E}SC}= 9.20  ±  2.80 MPa, respectively. These results are compared to those reported in the literature by utilizing various methods, and good agreements are found. The current approach eliminates the measurement inaccuracies associated with the physical contact. Exciting and detecting cell dynamics at micro-second time-scales is significantly faster than the

  9. Rugged single domain antibody detection elements for Bacillus anthracis spores and vegetative cells.

    Directory of Open Access Journals (Sweden)

    Scott A Walper

    Full Text Available Significant efforts to develop both laboratory and field-based detection assays for an array of potential biological threats started well before the anthrax attacks of 2001 and have continued with renewed urgency following. While numerous assays and methods have been explored that are suitable for laboratory utilization, detection in the field is often complicated by requirements for functionality in austere environments, where limited cold-chain facilities exist. In an effort to overcome these assay limitations for Bacillus anthracis, one of the most recognizable threats, a series of single domain antibodies (sdAbs were isolated from a phage display library prepared from immunized llamas. Characterization of target specificity, affinity, and thermal stability was conducted for six sdAb families isolated from rounds of selection against the bacterial spore. The protein target for all six sdAb families was determined to be the S-layer protein EA1, which is present in both vegetative cells and bacterial spores. All of the sdAbs examined exhibited a high degree of specificity for the target bacterium and its spore, with affinities in the nanomolar range, and the ability to refold into functional antigen-binding molecules following several rounds of thermal denaturation and refolding. This research demonstrates the capabilities of these sdAbs and their potential for integration into current and developing assays and biosensors.

  10. Parallel single-cell sequencing links transcriptional and epigenetic heterogeneity.

    Science.gov (United States)

    Angermueller, Christof; Clark, Stephen J; Lee, Heather J; Macaulay, Iain C; Teng, Mabel J; Hu, Tim Xiaoming; Krueger, Felix; Smallwood, Sebastien; Ponting, Chris P; Voet, Thierry; Kelsey, Gavin; Stegle, Oliver; Reik, Wolf

    2016-03-01

    We report scM&T-seq, a method for parallel single-cell genome-wide methylome and transcriptome sequencing that allows for the discovery of associations between transcriptional and epigenetic variation. Profiling of 61 mouse embryonic stem cells confirmed known links between DNA methylation and transcription. Notably, the method revealed previously unrecognized associations between heterogeneously methylated distal regulatory elements and transcription of key pluripotency genes.

  11. Femtosecond laser fabrication of optofluidic devices for single cell manipulation

    Directory of Open Access Journals (Sweden)

    Bragheri Francesca

    2015-01-01

    Full Text Available In this work we fabricate and validate two optofludic devices for the manipulation and analysis of single cells. The chips are fabricated by femtosecond laser micromachining exploiting the 3D capabilities of the technique and the inherent perfect alignment between microfluidic channels and optical networks. Both devices have been validated by probing the mechanical properties of different cancer cell lines, which are expected to show different elasticity because of their different metastatic potential.

  12. Bioanalytical tools for single-cell study of exocytosis.

    Science.gov (United States)

    Ge, Shencheng; Koseoglu, Secil; Haynes, Christy L

    2010-08-01

    Regulated exocytosis is a fundamental biological process used to deliver chemical messengers for cell-cell communication via membrane fusion and content secretion. A plethora of cell types employ this chemical-based communication to achieve crucial functions in many biological systems. Neurons in the brain and platelets in the circulatory system are representative examples utilizing exocytosis for neurotransmission and blood clotting. Single-cell studies of regulated exocytosis in the past several decades have greatly expanded our knowledge of this critical process, from vesicle/granule transport and docking at the early stages of exocytosis to membrane fusion and to eventual chemical messenger secretion. Herein, four main approaches that have been widely used to study single-cell exocytosis will be highlighted, including total internal reflection fluorescence microscopy, capillary electrophoresis, single-cell mass spectrometry, and microelectrochemistry. These techniques are arranged in the order following the route of a vesicle/granule destined for secretion. Within each section, the basic principles and experimental strategies are reviewed and representative examples are given revealing critical spatial, temporal, and chemical information of a secretory vesicle/granule at different stages of its lifetime. Lastly, an analytical chemist's perspective on potential future developments in this exciting field is discussed.

  13. Intra-laboratory validation of a human cell based in vitro angiogenesis assay for testing angiogenesis modulators

    Directory of Open Access Journals (Sweden)

    Jertta-Riina Sarkanen

    2011-01-01

    Full Text Available The developed standardized human cell based in vitro angiogenesis assay was intra-laboratory validated to verify that the method is reliable and relevant for routine testing of modulators of angiogenesis e.g. pharmaceuticals and industrial chemicals. This assay is based on the earlier published method but it was improved and shown to be more sensitive and rapid than the previous assay. The performance of the assay was assessed by using 6 reference chemicals, which are widely used pharmaceuticals that inhibit angiogenesis: acetyl salicylic acid, erlotinib, 2-methoxyestradiol, levamisole, thalidomide, and anti-vascular endothelial growth factor. In the intra-laboratory validation, the sensitivity of the assay (upper and lower limits of detection and linearity of response in tubule formation, batch to batch variation in tubule formation between different Master cell bank batches, and precision as well as the reliability of the assay (reproducibility and repeatability were tested. The pre-set acceptance criteria for the intra-laboratory validation study were met. The relevance of the assay in man was investigated by comparing the effects of reference chemicals and their concentrations to the published human data. The comparison showed a good concordance, which indicates that this human cell based angiogenesis model predicts well the effects in man and has the potential to be used to supplement and/or replace of animal tests.

  14. Single-cell epigenomics: powerful new methods for understanding gene regulation and cell identity.

    Science.gov (United States)

    Clark, Stephen J; Lee, Heather J; Smallwood, Sébastien A; Kelsey, Gavin; Reik, Wolf

    2016-04-18

    Emerging single-cell epigenomic methods are being developed with the exciting potential to transform our knowledge of gene regulation. Here we review available techniques and future possibilities, arguing that the full potential of single-cell epigenetic studies will be realized through parallel profiling of genomic, transcriptional, and epigenetic information.

  15. Radiosensitivity of kidney colony-forming cells: a short-term assay in situ in the mouse

    International Nuclear Information System (INIS)

    Ewen, C.; Hendry, J.H.

    1989-01-01

    A short-term colony assay for renal tubule epithelium has been developed. Uranyl nitrate (UN) is a heavy metal nephrotoxin that induces acute tubule necrosis followed by a large compensatory increase in the rate of cell proliferation in the nephron. UN was used to precipitate latent damage following renal irradiation. Using a subcapsular colony count at 14 days after unilateral irradiation, a single-dose cell survival curve was obtained with a D0 of 4.2 +/- 0.3 Gy. High-dose irradiation of an exteriorized kidney resulted in a survival curve which was biphasic, with a plateau in survival between 18 and 40 Gy. Subtraction of this plateau level from all the survival data gave D0 values of 2.5 +/- 0.2 Gy (data analyzed between 7.5 and 16 Gy) or 2.0 +/- 0.2 Gy (over range 12-16 Gy). The D0 value obtained at 20 months after bilateral (or unilateral) kidney irradiation, without the use of UN, was 2.9 +/- 1.1 Gy (over range 10-14 Gy)

  16. Assay for Listeria monocytogenes cells in whole blood using isotachophoresis and recombinase polymerase amplification.

    Science.gov (United States)

    Eid, Charbel; Santiago, Juan G

    2016-12-19

    We present a new approach which enables lysis, extraction, and detection of inactivated Listeria monocytogenes cells from blood using isotachophoresis (ITP) and recombinase polymerase amplification (RPA). We use an ITP-compatible alkaline and proteinase K approach for rapid and effective lysis. We then perform ITP purification to separate bacterial DNA from whole blood contaminants using a microfluidic device that processes 25 μL sample volume. Lysis, mixing, dispensing, and on-chip ITP purification are completed in a total of less than 50 min. We transfer extracted DNA directly into RPA master mix for isothermal incubation and detection, an additional 25 min. We first validate our assay in the detection of purified genomic DNA spiked into whole blood, and demonstrate a limit of detection of 16.7 fg μL -1 genomic DNA, the equivalent of 5 × 10 3 cells per mL. We then show detection of chemically-inactivated L. monocytogenes cells spiked into whole blood, and demonstrate a limit of detection of 2 × 10 4 cells per mL. Lastly, we show preliminary experimental data demonstrating the feasibility of the integration of ITP purification with RPA detection on a microfluidic chip. Our results suggest that ITP purification is compatible with RPA detection, and has potential to extend the applicability of RPA to whole blood.

  17. Experience with local lymph node assay performance standards using standard radioactivity and nonradioactive cell count measurements.

    Science.gov (United States)

    Basketter, David; Kolle, Susanne N; Schrage, Arnhild; Honarvar, Naveed; Gamer, Armin O; van Ravenzwaay, Bennard; Landsiedel, Robert

    2012-08-01

    The local lymph node assay (LLNA) is the preferred test for identification of skin-sensitizing substances by measuring radioactive thymidine incorporation into the lymph node. To facilitate acceptance of nonradioactive variants, validation authorities have published harmonized minimum performance standards (PS) that the alternative endpoint assay must meet. In the present work, these standards were applied to a variant of the LLNA based on lymph node cell counts (LNCC) run in parallel as a control with the standard LLNA with radioactivity measurements, with threshold concentrations (EC3) being determined for the sensitizers. Of the 22 PS chemicals tested in this study, 21 yielded the same results from standard radioactivity and cell count measurements; only 2-mercaptobenzothiazole was positive by LLNA but negative by LNCC. Of the 16 PS positives, 15 were positive by LLNA and 14 by LNCC; methylmethacrylate was not identified as sensitizer by either of the measurements. Two of the six PS negatives tested negative in our study by both LLNA and LNCC. Of the four PS negatives which were positive in our study, chlorobenzene and methyl salicylate were tested at higher concentrations than the published PS, whereas the corresponding concentrations resulted in consistent negative results. Methylmethacrylate and nickel chloride tested positive within the concentration range used for the published PS. The results indicate cell counts and radioactive measurements are in good accordance within the same LLNA using the 22 PS test substances. Comparisons with the published PS results may, however, require balanced analysis rather than a simple checklist approach. Copyright © 2011 John Wiley & Sons, Ltd.

  18. Determining antioxidant activities of lactobacilli cell-free supernatants by cellular antioxidant assay: a comparison with traditional methods.

    Directory of Open Access Journals (Sweden)

    Jiali Xing

    Full Text Available Antioxidant activity of lactic acid bacteria is associated with multiple health-protective effects. Traditional indexes of chemical antioxidant activities poorly reflect the antioxidant effects of these bacteria in vivo. Cellular antioxidant activity (CAA assay was used in this study to determine the antioxidant activity of cell-free supernatants (CFSs of 10 Lactobacillus strains. The performance of the CAA assay was compared with that of four chemical antioxidant activity assays, namely, DPPH radical scavenging, hydroxyl radical scavenging (HRS, reducing power (RP, and inhibition of linoleic acid peroxidation (ILAP. Results of the CAA assay were associated with those of DPPH and ILAP assays, but not with those of RP and HRS