scholarly journals Three step flow focusing enables image-based discrimination and sorting of late stage 1 Haematococcus pluvialis cells

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0249192
Author(s):  
Daniel Kraus ◽  
Andreas Kleiber ◽  
Enrico Ehrhardt ◽  
Matthias Leifheit ◽  
Peter Horbert ◽  
...  
Keyword(s):  
Late Stage ◽  
Haematococcus Pluvialis ◽  
Lateral Displacement ◽  
Microfluidic Channel ◽  
Image Features ◽  
Target Cells ◽  
Flow Focusing ◽  
Step Flow ◽  
Stage 1 ◽  
Mixed Stage

Label-free and gentle separation of cell stages with desired target properties from mixed stage populations are a major research task in modern biotechnological cultivation process and optimization of micro algae. The reported microfluidic sorter system (MSS) allows the subsequent investigation of separated subpopulations. The implementation of a viability preserving MSS is shown for separation of late stage 1 Haematococcus pluvialis (HP) cells form a mixed stage population. The MSS combines a three-step flow focusing unit for aligning the cells in single file transportation mode at the center of the microfluidic channel with a pure hydrodynamic sorter structure for cell sorting. Lateral displacement of the cells into one of the two outlet channels is generated by piezo-actuated pump chambers. In-line decision making for sorting is based on a user-definable set of image features and properties. The reported MSS significantly increased the purity of target cells in the sorted population (94%) in comparison to the initial mixed stage population (19%).

scholarly journals Shrinking microbubbles with microfluidics: mathematical modelling to control microbubble sizes

2021 ◽  
Author(s):  
A. Salari ◽  
V. Gnyawali ◽  
I. M. Griffiths ◽  
R. Karshafian ◽  
Michael C. Kolios ◽  
...  
Keyword(s):  
Life Sciences ◽  
Microfluidic Channel ◽  
Flow Focusing ◽  
Bubble Generation ◽  
Microfluidic Platform ◽  
Interfacial Tensions ◽  
Precise Control ◽  
Ultrasound Diagnostics ◽  
Bubble Sizes ◽  
Good Agreement

Microbubbles have applications in industry and life-sciences. In medicine, small encapsulated bubbles (< 10 μm) are desirable because of their utility in drug/oxygen delivery, sonoporation, and ultrasound diagnostics. While there are various techniques for generating microbubbles, microfluidic methods are distinguished due to their precise control and ease-offabrication. Nevertheless, sub-10 μm diameter bubble generation using microfluidics remains challenging, and typically requires expensive equipment and cumbersome setups. Recently, our group reported a microfluidic platform that shrinks microbubbles to sub-10 μm diameters. The microfluidic platform utilizes a simple microbubble-generating flow-focusing geometry, integrated with a vacuum shrinkage system, to achieve microbubble sizes that are desirable in medicine, and pave the way to eventual clinical uptake of microfluidically generated microbubbles. A theoretical framework is now needed to relate the size of the microbubbles produced and the system’s input parameters. In this manuscript, we characterize microbubbles made with various lipid concentrations flowing in solutions that have different interfacial tensions, and monitor the changes in bubble size along the microfluidic channel under various vacuum pressures. We use the physics governing the shrinkage mechanism to develop a mathematical model that predicts the resulting bubble sizes and elucidates the dominant parameters controlling bubble sizes. The model shows a good agreement with the experimental data, predicting the resulting microbubble sizes under different experimental input conditions. We anticipate that the model will find utility in enabling users of the microfluidic platform to engineer bubbles of specific sizes.

scholarly journals CD4- and Time-Dependent Susceptibility of HIV-1-Infected Cells to Antibody-Dependent Cellular Cytotoxicity

2019 ◽  
Vol 93 (10) ◽  
Author(s):  
Wen Shi Lee ◽  
Jérémie Prévost ◽  
Jonathan Richard ◽  
Reneé M. van der Sluis ◽  
Sharon R. Lewin ◽  
...  
Keyword(s):  
Late Stage ◽  
De Novo ◽  
Nk Cell ◽  
Early Stage ◽  
Time Dependent ◽  
Target Cells ◽  
Cellular Cytotoxicity ◽  
Antibody Dependent Cellular Cytotoxicity ◽  
Infected Cells ◽  
Hiv 1

ABSTRACTHIV-1-specific antibody-dependent cellular cytotoxicity (ADCC) antibodies within HIV-1-positive (HIV-1+) individuals predominantly target CD4-induced (CD4i) epitopes on HIV-1 envelope glycoprotein (Env). These CD4i epitopes are usually concealed on the surface of infected cells due to CD4 downregulation by the HIV-1 accessory proteins Nef and Vpu. We hypothesized that early-stage infected cells in the process of downregulating CD4 could be more susceptible to ADCC than late-stage infected cells that have fully downregulated CD4. There was significantly higher binding of antibodies within plasma from HIV-1-infected individuals to early-stage infected cells expressing intermediate levels of CD4 (CD4-intermediate cells) than in late-stage infected cells expressing low levels of CD4 (CD4-low cells). However, we noted that HIV-1-uninfected bystander cells and HIV-1-infected cells, at various stages of downregulating CD4, were all susceptible to NK cell-mediated ADCC. Importantly, we observed that the cytolysis of bystander cells and early infected cells in this culture system was driven by sensitization of target cells by inoculum-derived HIV-1 Env or virions. This phenomenon provided Env to target cells prior tode novoEnv expression, resulting in artifactual ADCC measurements. Future studies should take into consideration the inherent caveats ofin vitroinfection systems and develop improved models to address the potential role for ADCC against cells with nascent HIV-1 infection.IMPORTANCEAn increasing body of evidence suggests that ADCC contributes to protection against HIV-1 acquisition and slower HIV-1 disease progression. Targeting cells early during the infection cycle would be most effective in limiting virus production and spread. We hypothesized that there could be a time-dependent susceptibility of HIV-1-infected cells to ADCC in regard to CD4 expression. We observed NK cell-mediated ADCC of HIV-1-infected cells at multiple stages of CD4 downregulation. Importantly, ADCC of early infected cells appeared to be driven by a previously unappreciated problem of soluble Env and virions from the viral inoculum sensitizing uninfected cells to ADCC prior tode novoEnv expression. These results have implications for studies examining ADCC against cells with nascent HIV-1 infection.

Role of Mothers' Expansions in Stimulating Children's Language Production

1984 ◽  
Vol 27 (3) ◽  
pp. 387-396 ◽  
Author(s):  
Nancy J. Scherer ◽  
Lesley B. Olswang
Keyword(s):  
Late Stage ◽  
Language Production ◽  
Descriptive Analysis ◽  
Semantic Relations ◽  
Multiple Baseline ◽  
Linguistic Development ◽  
Experimental Procedure ◽  
Stage 1 ◽  
Treatment Design

Mothers' expansions were examined for their role in structuring conversational contributions and facilitating spontaneous imitations and productions of two-term semantic relations not previously used by their children. The subjects were four 2-year-old boys in late Stage 1 of linguistic development and their mothers. The investigation consisted of two studies. Study 1, a descriptive analysis of mother-child conversation, showed a contingent relationship between mothers' expansions and their children's use of spontaneous imitations. Study 2, an experimental procedure using a multiple baseline treatment design, showed that an increase in the mothers' expansions was systematically related to an increase in the children's initial spontaneous imitations of two-term semantic relations. Results also indicated that following the increase in spontaneous imitations, spontaneous productions of the two-term relations increased and were maintained, whereas spontaneous imitations subsequently decreased.

Staging Transitions In Li-Graphite : Phonon Spectra Of Dilute Stage 1

1982 ◽  
Vol 20 ◽  
Author(s):  
K.C. Woo ◽  
H. Mertwoy ◽  
J.E. Fischer ◽  
W.A. Kamitakahara ◽  
D.S. Robinson
Keyword(s):  
Phase Boundary ◽  
First Order ◽  
Phonon Spectra ◽  
Stage 1 ◽  
Mixed Stage

ABSTRACTFirst-order transitions to dilute stage one from stages 2,3 and 4 and from mixed stage 1+2 are observed in Li-graphite as predicted by Safran. The upper phase boundary is asymmetric in concentration and is sharply peaked about x ∼ 0.4. The phonons in the dilute stage 1 have energies between those of LiC6 and graphite. Unlike the stage 2 compounds, the compressibility does not scale in a simple way with intercalant density.

scholarly journals Human herpesvirus 7 infection increases the expression levels of CD46 and CD59 in target cells

2007 ◽  
Vol 88 (5) ◽  
pp. 1415-1422 ◽  
Author(s):  
Masaya Takemoto ◽  
Koichi Yamanishi ◽  
Yasuko Mori
Keyword(s):  
T Cells ◽  
Late Stage ◽  
Regulatory Protein ◽  
Flow Cytometric Analysis ◽  
Human Herpesvirus ◽  
Target Cells ◽  
Human Herpesvirus 6 ◽  
Flow Cytometric ◽  
Complement Dependent Cytotoxicity ◽  
Infected Cells

CD46 (membrane cofactor protein; MCP) is a molecule that functions as either a complement-regulatory protein (CRP) or a receptor for some pathogens, including human herpesvirus 6. DNA microarray analysis suggested that the expression of CD46 was upregulated in T cells infected with human herpesvirus 7 (HHV-7). Northen and Western blot analyses supported this result at both the transcriptional and translational levels. Flow-cytometric analysis revealed that upregulation of CD46 occurred at a late stage of infection in both SupT1 cells and primary CD4+ T cells, and also that expression of another CRP, CD59, was increased at a late stage of infection. Whether these CRPs actually function in HHV-7-infected cells was addressed and it was found that HHV-7-infected cells were more resistant to complement-dependent cytotoxicity than were uninfected cells. This study is the first report demonstrating that HHV-7 infection causes elevation of the CRPs CD46 and CD59, which may be a possible mechanism for HHV-7 to evade humoral immunity via complement.

Spherical Phospholipid Polymer Hydrogels for Cell Encapsulation Prepared with a Flow-Focusing Microfluidic Channel Device

Langmuir ◽  
2011 ◽  
Vol 28 (4) ◽  
pp. 2145-2150 ◽  
Author(s):  
Tatsuo Aikawa ◽  
Tomohiro Konno ◽  
Madoka Takai ◽  
Kazuhiko Ishihara
Keyword(s):  
Microfluidic Channel ◽  
Cell Encapsulation ◽  
Flow Focusing ◽  
Polymer Hydrogels ◽  
Phospholipid Polymer

Hydrodynamic nonadhesive cell retention in a microfluidic circuit for stressless suspension culture

2015 ◽  
Vol 7 (17) ◽  
pp. 7264-7269 ◽  
Author(s):  
Toyohito Naito ◽  
Noritada Kaji ◽  
Manabu Tokeshi ◽  
Takuya Kubo ◽  
Yoshinobu Baba ◽  
...  
Keyword(s):  
Suspension Culture ◽  
Lateral Displacement ◽  
Microfluidic Channel ◽  
Cell Retention ◽  
Deterministic Lateral Displacement ◽  
Loop Channel ◽  
Two Component

Cell collection based on deterministic lateral displacement (DLD) and cell circulation with a loop channel are two component technologies for stressless cell retention which have been developed with a view to working toward suspension culture in a microfluidic channel.

Capture of Very Rare Circulating Tumor Cells for Human Breast Cancer Diagnosis

2007 ◽  
Author(s):  
Taehyun Park ◽  
Timothy Jensen ◽  
Daniel Park ◽  
Jason Guy ◽  
Proyag Datta ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Tumor Cells ◽  
Circulating Tumor Cells ◽  
Cancer Diagnosis ◽  
Human Breast Cancer ◽  
Microfluidic Channel ◽  
Breast Cancer Diagnosis ◽  
Breast Cancer Cell Lines ◽  
Target Cells ◽  
Human Breast

A method of collecting and delivering single or precise numbers of cells to assess the feasibility of capturing very rare circulating tumor cells for human breast cancer diagnosis and monitoring was developed. A PMMA device was assembled with minimal assembly variation using passive alignment. Thermoplastic fusion bonding was optimized to yield minimal deformation of the microfluidic channel. UV modification and an anti-epithelial cell adhesion molecule (anti-EpCAM) functionalization process were used to generate capture surfaces and maximized by control experiment. Single or precise numbers of target cells were collected using a cell collecting capillary tube and a hemacytometer and delivered into the microchannel without any loss. Cells from one of the human breast cancer cell lines, the MCF-7 cell line (ATCC, Manassas, VA) which strongly overexpresses EpCAM, were successfully captured on the anti-EpCAM coated microchannel surfaces. Successful capture of early stage breast cancer cells in whole blood may be feasible with further optimization of the microchannel geometry and flow velocity through the microfluidic device.

scholarly journals 3-Step flow focusing enables multidirectional imaging of bioparticles for imaging flow cytometry

Lab on a Chip ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 1676-1686
Author(s):  
Andreas Kleiber ◽  
Anuradha Ramoji ◽  
Günter Mayer ◽  
Ute Neugebauer ◽  
Jürgen Popp ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Flow Focusing ◽  
Step Flow ◽  
Imaging Flow Cytometry ◽  
Focus Plane

The control of the focus plane allows multi-directional imaging flow cytometry.

Responses to Requests in the Dialogues of Mothers and Their Stage 1 Children

1982 ◽  
Vol 25 (1) ◽  
pp. 58-64 ◽  
Author(s):  
Nancy J. Scherer ◽  
Truman E. Coggins
Keyword(s):  
Late Stage ◽  
Binomial Distribution ◽  
Sequential Analysis ◽  
Semantic Information ◽  
Semantic Relationships ◽  
Lag Sequential Analysis ◽  
Significant Difference ◽  
Stage 1

The development of conversation requires children to learn to relate their utterances to utterances from other speakers. This investigation examined one method in which children relate their utterances to preceding utterances in conversation, namely, response utterances to request utterances. Late Stage 1 children's responses were examined for their pragmatic and semantic relationships to five types of requests used by mothers. Conditional (child responses to mother's requests) and unconditional (child responses following mother's utterances) probabilities were generated using the lag sequential analysis. The level of significant difference between the conditional and unconditional probabilities was determined with the binomial distribution. The results indicate that the children produced contingent linguistic responses to the mothers' requests based on the pragmatic intent of the requests—specifically, those requesting semantic information, clarifying a misunderstood remark, and requesting agreement or disagreement with a proposition. Further, the children's responses to the mothers" requests for semantic information provided the appropriate semantic information requested by the mothers. The children produced contingent nonlinguistic responses to the mothers' requests for an action to be performed, whereas contingent nonlinguistic or linguistic responses following the mothers' requests for attention failed to achieve significance. These findings indicate that responses to requests are important in the development of early contingent speech and provide one means for structuring conversation with Late Stage 1 children.

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