The development and characterization of a human mesothelioma in vitro 3D model to investigate immunotoxin therapy.

BackgroundTumor microenvironments present significant barriers to penetration by antibodies and immunoconjugates. Tumor microenvironments, however, are difficult to study in vitro. Cells cultured as monolayers exhibit less resistance to therapy than those grown in vivo and an alternative research model more representative of the in vivo tumor is more desirable. SS1P is an immunotoxin composed of the Fv portion of a mesothelin-specific antibody fused to a bacterial toxin that is presently undergoing clinical trials in mesothelioma.Methodology/principal findingsHere, we examined how the tumor microenvironment affects the penetration and killing activity of SS1P in a new three-dimensional (3D) spheroid model cultured in vitro using the human mesothelioma cell line (NCI-H226) and two primary cell lines isolated from the ascites of malignant mesothelioma patients. Mesothelioma cells grown as monolayers or as spheroids expressed comparable levels of mesothelin; however, spheroids were at least 100 times less affected by SS1P. To understand this disparity in cytotoxicity, we made fluorescence-labeled SS1P molecules and used confocal microscopy to examine the time course of SS1P penetration within spheroids. The penetration was limited after 4 hours. Interestingly, we found a significant increase in the number of tight junctions in the core area of spheroids by electron microscopy. Expression of E-Cadherin, a protein involved in the assembly and sealing of tight junctions and highly expressed in malignant mesothelioma, was found significantly increased in spheroids as compared to monolayers. Moreover, we found that siRNA silencing and antibody inhibition targeting E-Cadherin could enhance SS1P immunotoxin therapy in vitro.Conclusion/significanceThis work is one of the first to investigate immunotoxins in 3D tumor spheroids in vitro. This initial description of an in vitro tumor model may offer a simple and more representative model of in vivo tumors and will allow for further investigations of the microenvironmental effects on drug penetration and tumor cell killing. We believe that the methods developed here may apply to the studies of other tumor-targeting antibodies and immunoconjugates in vitro

Extending Feynman's Formalisms for Modelling Human Joint Action Coordination

The recently developed Life-Space-Foam approach to goal-directed human action deals with individual actor dynamics. This paper applies the model to characterize the dynamics of co-action by two or more actors. This dynamics is modelled by: (i) a two-term joint action (including cognitive/motivatonal potential and kinetic energy), and (ii) its associated adaptive path integral, representing an infinite--dimensional neural network. Its feedback adaptation loop has been derived from Bernstein's concepts of sensory corrections loop in human motor control and Brooks' subsumption architectures in robotics. Potential applications of the proposed model in human--robot interaction research are discussed. Keywords: Psycho--physics, human joint action, path integralsComment: 6 pages, Late

WMAP constraints on the Intra-Cluster Medium

We devise a Monte-Carlo based, optimized filter match method to extract the thermal Sunyaev-Zel'dovich (SZ) signature of a catalog of 116 low-redshift X-ray clusters from the first year data release of the Wilkinson Microwave Anisotropy Probe (WMAP). We detect an over-all amplitude for the SZ signal at the ~ 8-sigma level, yielding a combined constraint of f_{gas}h = 0.08 +/- 0.01 (ran) +/- 0.01 (sys) on the gas mass fraction of the Intra-Cluster Medium. We also compile X-ray estimated gas fractions from the literature for our sample, and find that they are consistent with the SZ estimates at the 2-sigma level, while both show an increasing trend with X-ray temperature. Nevertheless, our SZ estimated gas fraction is 30-40% smaller than the concordance LCDM cosmic average. We also express our observations in terms of the SZ flux-temperature relation, and compare it with other observations, as well as numerical studies. Based on its spectral and spatial signature, we can also extract the microwave point source signal of the clusters at the 3-sigma level, which puts the average microwave luminosity (at ~ 41 GHz) of bright cluster members (M_K < -21) at (2.4 +/- 0.8) x 10^{27} h^{-2} erg/s/Hz. Furthermore, we can constrain the average dark matter halo concentration parameter to c_{vir}=3.4+0.6-0.9, for clusters with T_x > 5 kev. Our work serves as an example for how correlation of SZ surveys with cluster surveys in other frequencies can significantly increase our physical understanding of the intra-cluster medium.Comment: 34 pages, 6 ps figures, Extended discussion of theoretical uncertainties, radio sources, and future prospects, Accepted for Publication in Ap

Open star clusters in the Milky Way - Comparison of photometric and trigonometric distance scales based on Gaia TGAS data

The global survey of star clusters in the Milky Way (MWSC) is a comprehensive list of 3061 objects that provides, among other parameters, distances to clusters based on isochrone fitting. The Tycho-Gaia Astrometric Solution (TGAS) catalogue, which is a part of Gaia data release 1 (Gaia DR1), delivers accurate trigonometric parallax measurements for more than 2 million stars, including those in star clusters. We compare the open cluster photometric distance scale with the measurements given by the trigonometric parallaxes from TGAS to evaluate the consistency between these values. The average parallaxes of probable cluster members available in TGAS provide the trigonometric distance scale of open clusters, while the photometric scale is given by the distances published in the MWSC. Sixty-four clusters are suited for comparison as they have more than 16 probable members with parallax measurements in TGAS. We computed the average parallaxes of the probable members and compared these to the photometric parallaxes derived within the MWSC. We find a good agreement between the trigonometric TGAS-based and the photometric MWSC-based distance scales of open clusters, which for distances less than 2.3 kpc coincide at a level of about 0.1 mas with no dependence on the distance. If at all, there is a slight systematic offset along the Galactic equator between $30^\circ$ and $160^\circ$ galactic longitude.Comment: Accepted for publication as a Letter in Astronomy and Astrophysics, 4 pages, 4 figure

Deconstructing Cation-pi Interactions: Understanding the Binding Energies Involved with Metal and Aromatic Amino Acid Residues

The Effective Fragment Potential (EFP) method is a computationally efficient technique for describing non-covalent interactions, such as hydrogen bonding and van der Waals forces. Cation-pi interactions are a type of non-covalent interactions and are thought to be important in biological processes, such as permittivity of ion channels. The goal of our work is to establish that the EFP method reliably describes the strength, directionality, and composition of cation-pi interactions. Optimal geometries were found for a series of biologically relevant cations (K+, Li+, Na+, Ca2+, and Mg2+) and aryl moieties appearing as residue groups in natural amino acids (3-methyl-1h-indole, p-cresol, phenylalanine, toluene, and tyrosine) using the MP2 level of theory and the cc-pVTZ basis set. The cation was then displaced along a line normal to the aromatic compound with EFP calculations performed for every 0.2 angstroms between 1 and 7 angstroms along the trajectory. The obtained binding energies and relative energy components were compared against Symmetry-Adapted Pertubation Theory (SAPT) calculations at 0.4 angstrom increments along the same trajectory. SAPT has been previously used to test the accuracy of EFP for a variety of systems. Preliminary results indicate that the EFP method accurately predicts equilibrium geometries in cation-pi complexes. The low computational cost of EFP against SAPT provides promise in expansion on the research of cation-pi interactions to larger systems using EFP