scholarly journals Existence of a Conserved Quantity and Stability of In Vitro Virus Infection Dynamics Models with Absorption Effect

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Celia Martínez-Lázaro ◽  
Marco Antonio Taneco-Hernández ◽  
Ramón Reyes-Carreto ◽  
Cruz Vargas-De-León
Keyword(s):  
Experimental Data ◽  
Equilibrium Points ◽  
First Integral ◽  
Conserved Quantity ◽  
Target Cells ◽  
Estimation Of Parameters ◽  
Infection Dynamics ◽  
A Cell ◽  
Dynamics Models

The estimation of parameters in biomathematical models is useful to characterize quantitatively the dynamics of biological processes. In this paper, we consider some systems of ordinary differential equations (ODEs) modelling the viral dynamics in a cell culture. These models incorporate the loss of viral particles due to the absorption into target cells. We estimated the parameters of models by least-squares minimization between numerical solution of the system and experimental data of cell cultures. We derived a first integral or conserved quantity, and we proved the use of experimental data in order to test the conservation law. The systems have nonhyperbolic equilibrium points, and the conditions for their stability are obtained by using a Lyapunov function. We complemented these theoretical results with some numerical simulations.

scholarly journals Diminished LcrV Secretion Attenuates Yersinia pseudotuberculosis Virulence

2007 ◽  
Vol 189 (23) ◽  
pp. 8417-8429 ◽  
Author(s):  
Jeanette E. Bröms ◽  
Matthew S. Francis ◽  
Åke Forsberg
Keyword(s):  
Type Iii Secretion ◽  
Yersinia Pseudotuberculosis ◽  
Signal Sequence ◽  
Infection Model ◽  
Target Cells ◽  
Cell Infection ◽  
Host Cell Membrane ◽  
Type Iii ◽  
A Cell

ABSTRACT Many gram-negative bacterial pathogenicity factors that function beyond the outer membrane are secreted via a contact-dependent type III secretion system. Two types of substrates are predestined for this mode of secretion, namely, antihost effectors that are translocated directly into target cells and the translocators required for targeting of the effectors across the host cell membrane. N-terminal secretion signals are important for recognition of the protein cargo by the type III secretion machinery. Even though such signals are known for several effectors, a consensus signal sequence is not obvious. One of the translocators, LcrV, has been attributed other functions in addition to its role in translocation. These functions include regulation, presumably via interaction with LcrG inside bacteria, and immunomodulation via interaction with Toll-like receptor 2. Here we wanted to address the significance of the specific targeting of LcrV to the exterior for its function in regulation, effector targeting, and virulence. The results, highlighting key N-terminal amino acids important for LcrV secretion, allowed us to dissect the role of LcrV in regulation from that in effector targeting/virulence. While only low levels of exported LcrV were required for in vitro effector translocation, as deduced by a cell infection assay, fully functional export of LcrV was found to be a prerequisite for its role in virulence in the systemic murine infection model.

scholarly journals CRISPR-mediated isogenic cell-SELEX approach for generating highly specific aptamers against native membrane proteins

2020 ◽  
Author(s):  
Jonah C. Rosch ◽  
Emma H. Neal ◽  
Daniel A. Balikov ◽  
Mohsin Rahim ◽  
Ethan S. Lippmann
Keyword(s):  
Membrane Proteins ◽  
Glucose Transporter ◽  
High Specificity ◽  
Epithelial Cell Line ◽  
Target Cells ◽  
Wild Type ◽  
Simultaneous Exposure ◽  
Affinity Reagents ◽  
A Cell

AbstractIntroductionThe generation of affinity reagents that bind native membrane proteins with high specificity remains challenging. Most in vitro selection paradigms utilize different cell types for positive and negative rounds of selection (where the positive selection is against a cell that expresses the desired membrane protein and the negative selection is against a cell that lacks the protein). However, this strategy can yield affinity reagents that bind unintended membrane proteins on the target cells. To address this issue, we developed a systematic evolution of ligands by exponential enrichment (SELEX) scheme that utilizes isogenic pairs of cells generated via CRISPR techniques.MethodsUsing a Caco-2 epithelial cell line with constitutive Cas9 expression, we knocked out the SLC2A1 gene (encoding the GLUT1 glucose transporter) via lipofection with synthetic gRNAs. Cell-SELEX rounds were carried out against wild-type and GLUT1-null cells using a single-strand DNA (ssDNA) library. Next-generation sequencing (NGS) was used to quantify enrichment of prospective binders to the wild-type cells.Results10 rounds of cell-SELEX were conducted via simultaneous exposure of ssDNA pools to wild-type and GLUT1-null Caco-2 cells under continuous perfusion. The top binders identified from NGS were validated by flow cytometry and immunostaining for their specificity to the GLUT1 receptor.ConclusionsOur data indicate that highly specific aptamers can be isolated with a SELEX strategy that utilizes isogenic cell lines. This approach should be broadly useful for generating affinity reagents that selectively bind to membrane proteins in their native conformations on the cell surface.

scholarly journals Primary generation of cytolytic T lymphocytes in the absence of DNA synthesis.

1979 ◽  
Vol 150 (1) ◽  
pp. 196-201 ◽  
Author(s):  
H R MacDonald ◽  
R K Less
Keyword(s):  
T Lymphocytes ◽  
Dna Synthesis ◽  
Cytolytic Activity ◽  
Target Cells ◽  
Cytolytic T Lymphocytes ◽  
Spleen Cells ◽  
Con A ◽  
A Cell ◽  
Stimulation Of

The requirement for DNA synthesis during the primary differentiation of cytolytic T lymphocytes (CTL) had been investigated. CTL were induced polyclonally in vitro by stimulation of normal C57BL/6 spleen cells with concanavalin A (Con A)and their cytolytic activity was tested against 51Cr-labeled target cells in the presence of Bacto Phytohemagglutinin M. With this system, CTL activity could first be detected 48 h after exposure of spleen cells to Con A. Addition of cytosine arabinoside at concentrations sufficient to reduce DNA synthesis by 95-98% in Con A-stimulated cultures did not significantly inhibit the generation of cytolytic activity on a cell-to-cell basis. These results demonstrate that derepression of the genetic information required for the expression of CTL function can occur in the absence of detectable DNA synthesis.

scholarly journals Cytotoxicity as a Fundamental Response to Xenobiotics

2021 ◽  
Author(s):  
Grethel León-Mejía ◽  
Alvaro Miranda Guevara ◽  
Ornella Fiorillo Moreno ◽  
Carolina Uribe Cruz
Keyword(s):  
Medical Devices ◽  
Normal Cell ◽  
Cellular Damage ◽  
In Vitro Tests ◽  
Target Cells ◽  
Cell Physiology ◽  
A Cell ◽  
Division Cell

Cytotoxicity refers to the ability of a molecule or a compound to cause some type of cellular damage, of which some of the adverse effects that can occur include injuries to some structures or the fundamental processes involved in cell maintenance, such as survival, cell division, cell biochemistry, and the normal cell physiology. The potential for cytotoxicity is one of the first tests that must be performed to determine the effects of drugs, biomolecules, nanomaterials, medical devices, pesticides, heavy metals, and solvents, among others. This potential may be oriented in the mechanism under which it generates cell death, the dose, and the target cells that generate the response. The evaluation of the toxicologic and cytotoxic properties of the chemical substances through in vitro tests has become a competitive alternative to in vivo experimentation as a consequence of ethical considerations. Presently, there are numerous tests conducted to evaluate the cytotoxicity of a certain agent, the selection of which depends on the purpose of the study. In this sense, the present review provides a general overview of the different responses of a cell to xenobiotic agents and the different test that can be useful for evaluation of these responses.

scholarly journals A hybrid PDE–ABM model for viral dynamics with application to SARS–CoV–2 and influenza

2021 ◽  
Author(s):  
Sadegh Marzban ◽  
Renji Han ◽  
Nóra Juhász ◽  
Gergely Röst
Keyword(s):  
Continuous Variable ◽  
Virus Concentration ◽  
Viral Dynamics ◽  
Agent Based ◽  
Ode System ◽  
Infection Dynamics ◽  
A Cell ◽  
Spatio Temporal ◽  
Insight Into

We propose a hybrid partial differential equation - agent-based (PDE-ABM) model to describe the spatio-temporal viral dynamics in a cell population. The virus concentration is considered as a continuous variable and virus movement is modeled by diffusion, while changes in the states of cells (i.e. healthy, infected, dead) are represented by a stochastic agent-based model. The two subsystems are intertwined: the probability of an agent getting infected in the ABM depends on the local viral concentration, and the source term of viral production in the PDE is determined by the cells that are infected. We develop a computational tool that allows us to study the hybrid system and the generated spatial patterns in detail. We systematically compare the outputs with a classical ODE system of viral dynamics and find that the ODE model is a good approximation only if the diffusion coefficient is large. We demonstrate that the model is able to predict SARS-CoV-2 infection dynamics and replicate the output of in vitro experiments. Applying the model to influenza as well, we can gain insight into why the outcomes of these two infections are different.

scholarly journals CELLS MEDIATING SPECIFIC IN VITRO CYTOTOXICITY

1972 ◽  
Vol 135 (4) ◽  
pp. 890-906 ◽  
Author(s):  
Pierre Golstein ◽  
Hans Wigzell ◽  
Henric Blomgren ◽  
Erik A. J. Svedmyr
Keyword(s):  
T Cells ◽  
In Vitro Cytotoxicity ◽  
Cell Populations ◽  
Target Cells ◽  
Present System ◽  
Spleen Cells ◽  
A Cell ◽  
Thymus Cells ◽  
Immune Spleen Cells

In order to investigate whether only T cells are involved in a cell-mediated cytotoxic system in vitro, we tested the cytotoxicity of immune killing cell populations as deprived as possible of B cells. Educated thymus cells, immune spleen cells purified by filtration through a column of beads coated with antimouse Ig antiserum, and finally educated thymus cells further purified by filtration through such a column fully retained their specific cytotoxic activity. This very strongly suggests that only T cells are involved in the killing of target cells by allogeneic immune cells in vitro, in this system. Receptor-bearing cells involved in killing in the present system are thus very probably T cells. This point was further strengthened by the demonstration of specific adsorption, on the relevant monolayers, of each of the three above mentioned killing cell populations.

scholarly journals SUPPRESSION OF GLIOBLASTOMA CELLULAR TRANSPORTERS SENSITIZES TARGET CELLS TO INFECTION WITH ONCOLYTIC VIRUS IN THE PRESENCE OF IONIZING RADIATION

2015 ◽  
Vol 14 (2) ◽  
pp. 65-70
Author(s):  
I. V. Ulasov ◽  
N. V. Kaverina ◽  
Z. G. Kadagidze ◽  
A. Yu. Baryshnikov
Keyword(s):  
Experimental Data ◽  
Ionizing Radiation ◽  
Cancer Cells ◽  
Adenoviral Vector ◽  
Oncolytic Virus ◽  
Target Cells ◽  
Glioblastoma Cell ◽  
The Brain ◽  
Glioblastoma Cell Lines

It is already established that verapamil inhibits Pgp expression in the brain tumor cancer cells such as medulloblastoma. The aim of this study is to investigate the sensitivity of glioblastoma cancer cells to verapamil and its combination with oncolytic adenoviral victor CRAd-S-pK7. In vitro using U87 and U251 human glioblastoma cell lines, we obtained experimental data suggesting a therapeutic effect of verapamil and CRAd-S-pK7. Moreover, we established that verapamil improves anti-glioma effect of oncolytic adenoviral vector in the presence of ionizing radiation, which results into more suppression of U251 cancer cells via inhibition of their proliferation.

scholarly journals In cellulo phosphorylation induces pharmacological reprogramming of maurocalcin, a cell-penetrating venom peptide

2016 ◽  
Vol 113 (17) ◽  
pp. E2460-E2468 ◽  
Author(s):  
Michel Ronjat ◽  
Wei Feng ◽  
Lucie Dardevet ◽  
Yao Dong ◽  
Sawsan Al Khoury ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Phosphorylation Site ◽  
Ex Situ ◽  
Target Cells ◽  
Allosteric Modulator ◽  
Venom Peptide ◽  
First Case ◽  
A Cell ◽  
Negative Allosteric Modulator

The venom peptide maurocalcin (MCa) is atypical among toxins because of its ability to rapidly translocate into cells and potently activate the intracellular calcium channel type 1 ryanodine receptor (RyR1). Therefore, MCa is potentially subjected to posttranslational modifications within recipient cells. Here, we report that MCa Thr26 belongs to a consensus PKA phosphorylation site and can be phosphorylated by PKA both in vitro and after cell penetration in cellulo. Unexpectedly, phosphorylation converts MCa from positive to negative RyR1 allosteric modulator. Thr26 phosphorylation leads to charge neutralization of Arg24, a residue crucial for MCa agonist activity. The functional effect of Thr26 phosphorylation is partially mimicked by aspartyl mutation. This represents the first case, to our knowledge, of both ex situ posttranslational modification and pharmacological reprogramming of a small natural cystine-rich peptide by target cells. So far, phosphorylated MCa is the first specific negative allosteric modulator of RyR1, to our knowledge, and represents a lead compound for further development of phosphatase-resistant analogs.

scholarly journals A hybrid PDE–ABM model for viral dynamics with application to SARS-CoV-2 and influenza

2021 ◽  
Vol 8 (11) ◽  
Author(s):  
Sadegh Marzban ◽  
Renji Han ◽  
Nóra Juhász ◽  
Gergely Röst
Keyword(s):  
Continuous Variable ◽  
Virus Concentration ◽  
Viral Dynamics ◽  
Agent Based ◽  
Ode System ◽  
Infection Dynamics ◽  
A Cell ◽  
Spatio Temporal ◽  
Insight Into

We propose a hybrid partial differential equation–agent-based (PDE–ABM) model to describe the spatio-temporal viral dynamics in a cell population. The virus concentration is considered as a continuous variable and virus movement is modelled by diffusion, while changes in the states of cells (i.e. healthy, infected, dead) are represented by a stochastic ABM. The two subsystems are intertwined: the probability of an agent getting infected in the ABM depends on the local viral concentration, and the source term of viral production in the PDE is determined by the cells that are infected. We develop a computational tool that allows us to study the hybrid system and the generated spatial patterns in detail. We systematically compare the outputs with a classical ODE system of viral dynamics, and find that the ODE model is a good approximation only if the diffusion coefficient is large. We demonstrate that the model is able to predict SARS-CoV-2 infection dynamics, and replicate the output of in vitro experiments. Applying the model to influenza as well, we can gain insight into why the outcomes of these two infections are different.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

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