168 research outputs found
Uterine Mast Cells and Immunoglobulin-E Antibody Responses During Clearance of \u3ci\u3eTritrichomonas foetus\u3c/i\u3e
We showed earlier that Tritrichomonas foetus–specific bovine immunoglobulin (Ig)G1 and IgA antibodies in uterine and vaginal secretions are correlated with clearance of this sexually transmitted infection. Eosinophils have been noted in previous studies of bovine trichomoniasis but the role of mast cells and IgE responses have not been reported. The hypothesis that IgE and mast cell degranulation play a role in clearance was tested in 25 virgin heifers inseminated experimentally and infected intravaginally with T. foetus strain D1 at estrus and cultured weekly. Groups were euthanatized at 3, 6, 9, or 12 weeks, when tissues were fixed and secretions were collected for culture and antibody analysis. Immunohistochemistry using a monoclonal antibody to a soluble lipophosphoglycan (LPG)–containing surface antigen (TF1.17) demonstrated antigen uptake by uterine epithelial cells. Lymphoid nodules were detected below antigen-positive epithelium. Little IgG2 antibody was detected but IgG1, IgA, IgM, and IgE T. foetus–specific antibodies increased in uterine secretions at weeks 6 and 9 after infection. This was inversely proportional to subepithelial mast cells numbers and most animals cleared the infection by the sampling time after the lowest mast cell count. Furthermore, soluble antigen was found in uterine epithelium above inductive sites (lymphoid nodules). Cross-linking of IgE on mast cells by antigen and perhaps LPG triggering appears to have resulted in degranulation. Released cytokines may account for production of predominantly Th2 (IgG1 and IgE) and IgA antibody responses, which are related to clearance of the infection
A Multiscale Modeling Framework Based on P Systems
Cellular systems present a highly complex organization at
different scales including the molecular, cellular and colony levels. The
complexity at each one of these levels is tightly interrelated. Integrative
systems biology aims to obtain a deeper understanding of cellular systems
by focusing on the systemic and systematic integration of the different
levels of organization in cellular systems.
The different approaches in cellular modeling within systems biology
have been classified into mathematical and computational frameworks.
Specifically, the methodology to develop computational models has been
recently called executable biology since it produces executable algorithms
whose computations resemble the evolution of cellular systems.
In this work we present P systems as a multiscale modeling framework
within executable biology. P system models explicitly specify the
molecular, cellular and colony levels in cellular systems in a relevant and
understandable manner. Molecular species and their structure are represented
by objects or strings, compartmentalization is described using
membrane structures and finally cellular colonies and tissues are modeled
as a collection of interacting individual P systems.
The interactions between the components of cellular systems are described
using rewriting rules. These rules can in turn be grouped together
into modules to characterize specific cellular processes. One of our current
research lines focuses on the design of cell systems biology models
exhibiting a prefixed behavior through the automatic assembly of these
cellular modules. Our approach is equally applicable to synthetic as well
as systems biology.Kingdom's Engineering and Physical Sciences Research Council EP/ E017215/1Biotechnology and Biological Sciences Research Council/United Kingdom BB/F01855X/1Biotechnology and Biological Sciences Research Council/United Kingdom BB/D019613/
Qualitative and quantitative analysis of systems and synthetic biology constructs using P systems
YesComputational models are perceived as an attractive alternative to mathematical models (e.g., ordinary differential equations). These models incorporate a set of methods for specifying, modeling, testing, and simulating biological systems. In addition, they can be analyzed using algorithmic techniques (e.g., formal verification). This paper shows how formal verification is utilized in systems and synthetic biology through qualitative vs quantitative analysis. Here, we choose two well-known case studies: quorum sensing in P. aeruginosas and pulse generator. The paper reports verification analysis of two systems carried out using some model checking tools, integrated to the Infobiotics Workbench platform, where system models are based on stochastic P systems.EPSR
Current density inhomogeneity throughout the thickness of superconducting films and its effect on their irreversible magnetic properties
We calculate the distribution of the current density in superconducting
films along the direction of an external field applied perpendicular to the
film plane. Our analysis reveals that in the presence of bulk pinning is
inhomogeneous on a length scale of order the inter vortex distance. This
inhomogeneity is significantly enhanced in the presence of surface pinning. We
introduce new critical state model, which takes into account the current
density variations throughout the film thickness, and show how these variations
give rise to the experimentally observed thickness dependence of and
magnetic relaxation rate.Comment: RevTex, 9 PS figures. To appear in Phys. Rev.
Evolving cell models for systems and synthetic biology
This paper proposes a new methodology for the automated design of cell models for systems and synthetic biology. Our modelling framework is based on P systems, a discrete, stochastic and modular formal modelling language. The automated design of biological models comprising the optimization of the model structure and its stochastic kinetic constants is performed using an evolutionary algorithm. The evolutionary algorithm evolves model structures by combining different modules taken from a predefined module library and then it fine-tunes the associated stochastic kinetic constants. We investigate four alternative objective functions for the fitness calculation within the evolutionary algorithm: (1) equally weighted sum method, (2) normalization method, (3) randomly weighted sum method, and (4) equally weighted product method. The effectiveness of the methodology is tested on four case studies of increasing complexity including negative and positive autoregulation as well as two gene networks implementing a pulse generator and a bandwidth detector. We provide a systematic analysis of the evolutionary algorithm’s results as well as of the resulting evolved cell models
Studies on Fabrication of Ag/HgBaCaCuO/CdSe Heterostructures by Pulse-Electrodeposition Route
Metal/superconductor/semiconductor (Ag/HgBaCaCuO/CdSe) heterostructures have
been successfully fabricated using pulse-electrodeposition technique. The
electrochemical parameters are optimized and diffusion free growth of CdSe onto
Ag/HgBaCaCuO was obtained by employing under-potential deposition and by
studying nucleation and growth mechanism during deposition. The
heterostructures are characterized by X-ray diffraction (XRD), full-width at
half-maximum (FWHM), scanning electron microscopy (SEM) studies and low
temperature four probe electrical resistivity measurements. After the
deposition of CdSe the critical transition temperature of HgBaCaCuO films was
found be increased from 115 K with Jc = 1.7 x 103 A/cm2 to 117.2 K with Jc =
1.91 x 103 A/cm2. When the heterostructure was irradiated with red He-Ne laser
(2 mW), the Tc was further enhanced to 120.3 K with Jc = 3.7 x 103 A/cm2. This
increase in superconducting parameters of HgBaCaCuO in Ag/ HgBaCaCuO/CdSe
heterostructure has been explained at length in this paper.
Keywords. Electrodeposition; Hg-based cuprate; semiconductor;
heterostructures; electrical properties.
PACS Nos 81.15.Pq; 74.72.Gr; 78.40.Fy; 84.37; 73.40 *E-mail:
[email protected], [email protected]: 22 Pages, 12 Figures. Submitted to Semiconductor Science and
Technology. Submitted to Semiconductor Science and Technolog
A Novel Behavioral Assay for Measuring Cold Sensation in Mice
Behavioral models of cold responses are important tools for exploring the molecular mechanisms of cold sensation. To complement the currently cold behavioral assays and allow further studies of these mechanisms, we have developed a new technique to measure the cold response threshold, the cold plantar assay. In this assay, animals are acclimated on a glass plate and a cold stimulus is applied to the hindpaw through the glass using a pellet of compressed dry ice. The latency to withdrawal from the cooled glass is used as a measure of the cold response threshold of the rodents, and the dry ice pellet provides a ramping cold stimulus on the glass that allows the correlation of withdrawal latency values to rough estimates of the cold response threshold temperature. The assay is highly sensitive to manipulations including morphine-induced analgesia, Complete Freund's Adjuvant-induced inflammatory allodynia, and Spinal Nerve Ligation-induced neuropathic allodynia
Influence of Shear-Thinning Rheology on the Mixing Dynamics in Taylor-Couette Flow
Non‐Newtonian rheology can have a significant effect on mixing efficiency, which remains poorly understood. The effect of shear‐thinning rheology in a Taylor‐Couette reactor is studied using a combination of particle image velocimetry and flow visualization. Shear‐thinning is found to alter the critical Reynolds numbers for the formation of Taylor vortices and the higher‐order wavy instability, and is associated with an increase in the axial wavelength. Strong shear‐thinning and weak viscoelasticity can also lead to sudden transitions in wavelength as the Reynolds number is varied. Finally, it is shown that shear‐thinning causes an increase in the mixing time within vortices, due to a reduction in their circulation, but enhances the axial dispersion of fluid in the reactor
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