165 research outputs found
Radiolabelling of antigen and liposomes for vaccine biodistribution studies
A relatively simple and effective method to follow the movement of pharmaceutical preparations such as vaccines in biodistribution studies is to radiolabel the components. Whilst single radiolabelling is common practice, in vaccine systems containing adjuvants the ability to follow both the adjuvant and the antigen is favourable. To this end, we have devised a dual-radiolabelling method whereby the adjuvant (liposomes) is labelled with 3H and the antigen (a subunit protein) with 125I. This model is stable and reproducible; we have shown release of the radiolabels to be negligible over periods of up to 1 week in foetal calf serum at 37° C. In this paper we describe the techniques which enable the radiolabelling of various components, assessing stability and processing of samples which all for their application in biodistribution studies. Furthermore we provide examples derived from our studies using this model in tuberculosis vaccine biodistribution studies
Nature and Nurture in Dark Matter Halos
Cosmological simulations consistently predict specific properties of dark
matter halos, but these have not yet led to a physical understanding that is
generally accepted. This is especially true for the central regions of these
structures. Recently two major themes have emerged. In one, the dark matter
halo is primarily a result of the sequential accretion of primordial structure
(ie `Nature'); while in the other, dynamical relaxation (ie `Nurture')
dominates at least in the central regions. Some relaxation is however required
in either mechanism. In this paper we accept the recently established
scale-free sub-structure of halos as an essential part of both mechanisms.
Consequently; a simple model for the central relaxation based on a self-similar
cascade of tidal interactions, is contrasted with a model based on the
accretion of adiabatically self-similar, primordial structure. We conclude that
a weak form of this relaxation is present in the simulations, but that is
normally described as the radial orbit instability.Comment: 25 pages, 3 figures, fig with parts 1 to d, fig 3 with parts a to
Reducing protein corona formation and enhancing colloidal stability of gold nanoparticles by capping with silica monolayers
A study demonstrated the reducing of protein corona (PC) formation and enhancing colloidal stability of gold nanoparticles (Au NP) by capping with silica monolayers. Au NP surface was needed to achieve silica monolayer formation. In a first attempt to have a high density ligand coverage around NS-1, an excess of 3-mercaptopropyltrimethoxysilane (MPTMS) was directly added to a Au NP hydrosol, but this resulted in immediate aggregation. The resulting trimethoxysilane moiety covering the surface of NS-3 was subsequently hydrolyzed by addition of 5 mM NaOH in a 2:1 methanol/water mixture, yielding a polymeric monolayer
Reversible control of protein corona formation on gold nanoparticles using host-guest interactions
When nanoparticles (NPs) are exposed to biological media, proteins are adsorbed, forming a so-called protein corona (PC). This cloud of protein aggregates hampers the targeting and transport capabilities of the NPs, thereby compromising their biomedical applications. Therefore, there is a high interest in the development of technologies that allow control over PC formation, as this would provide a handle to manipulate NPs in biological fluids. We present a strategy that enables the reversible disruption of the PC using external stimuli, thereby allowing a precise regulation of NP cellular uptake. The approach, demonstrated for gold nanoparticles (AuNPs), is based on a biorthogonal, supramolecular host-guest interactions between an anionic dye bound to the AuNP surface and a positively charged macromolecular cage. This supramolecular complex effectively behaves as a zwitterionic NP ligand, which is able not only to prevent PC formation but also to disrupt a previously formed hard corona. With this supramolecular stimulus, the cellular internalization of AuNPs can be enhanced by up to 30-fold in some cases, and even NP cellular uptake in phagocytic cells can be regulated. Additionally, we demonstrate that the conditional cell uptake of purposely designed gold nanorods can be used to selectively enhance photothermal cell death
Extended Press-Schechter theory and the density profiles of dark matter haloes
An inside-out model for the formation of haloes in a hierarchical clustering
scenario is studied. The method combines the picture of the spherical infall
model and a modification of the extended Press-Schechter theory. The mass
accretion rate of a halo is defined to be the rate of its mass increase due to
minor mergers. The accreted mass is deposited at the outer shells without
changing the density profile of the halo inside its current virial radius. We
applied the method to a flat Universe. The resulting density
profiles are compared to analytical models proposed in the literature, and a
very good agreement is found. A trend is found of the inner density profile
becoming steeper for larger halo mass, that also results from recent N-body
simulations. Additionally, present-day concentrations as well as their time
evolution are derived and it is shown that they reproduce the results of large
cosmological N-body simulations.Comment: 9 pages, 7 figures, accepted for publication in MNRA
Biocompatible, Multiresponsive Nanogel Composites for Codelivery of Antiangiogenic and Chemotherapeutic Agents
Single therapy approaches are usually insufficient to treat certain diseases, due to genetic differences between patients or disease resistance. Therefore, such approaches are gradually replaced by combination therapies comprising two or more drugs. In oncology, these include BRAF inhibitors and cytotoxic, antiangiogenic, or immunomodulatory agents, among others. We propose herein the use of multiresponsive nanogel composites for the codelivery of a DNA intercalator (doxorubicin) and an antiangiogenic and immunomodulatory agent (pomalidomide). We introduce a surfactant-free synthetic protocol to decorate biocompatible poly(ethylene glycol)methacrylate nanogels (PEGMA) with evenly distributed gold nanoparticles and explore their ability to deliver drugs upon stimulation by various triggers such as heat, light, and reducing agents present in the intracellular environment. We further demonstrate that an additional polymer coating on the nanogel surface can decrease uncontrolled drug leakage and modulate cellular uptake and the drug release profile
Remodeling arteries: studying the mechanical properties of 3D-bioprinted hybrid photoresponsive materials.
3D-printed cell models are currently in the spotlight of medical research. Whilst significant advances have been made, there are still aspects that require attention to achieve more realistic models which faithfully represent the in vivo environment. In this work we describe the production of an artery model with cyclic expansive properties, capable of mimicking the different physical forces and stress factors that cells experience in physiological conditions. The artery wall components are reproduced using 3D printing of thermoresponsive polymers with inorganic nanoparticles (NPs) representing the outer tunica adventitia, smooth muscle cells embedded in extracellular matrix representing the tunica media, and finally a monolayer of endothelial cells as the tunica intima. Cyclic expansion can be induced thanks to the inclusion of photo-responsive plasmonic NPs embedded within the thermoresponsive ink composition, resulting in changes in the thermoresponsive polymer hydration state and hence volume, in a stimulated on-off manner. By changing the thermoresponsive polymer composition, the transition temperature and pulsatility can be efficiently tuned. We show the direct effect of cyclic expansion and contraction on the overlying cell layers by analyzing transcriptional changes in mechanoresponsive mesenchymal genes associated with such microenvironmental physical cues. The technique described herein involving stimuli-responsive 3D printed tissue constructs, also described as four- dimensional (4D) printing, offers a novel approach for the production of dynamic biomodels.Financial support is acknowledged from the MCIN/AEI/
10.13039/501100011033 through grant # PID2019-108854RAI00. C. G. A. thanks to the Ministerio de Ciencia e InnovacioÂŽn
(MCIN) for a Juan de la Cierva IncorporacioÂŽn Fellowship
(IJC2019-040827-I). M. S.-A. is recipient of a RamoÂŽn y Cajal
contract and a ââGeneracioÂŽn de Conocimientoââ grant from the
Ministerio de Ciencia e InnovacioÂŽn (RYC2020-029690-I and
PID2021-128106NA-I00). MAdP is coordinator and PL of ââAtheroConvergenceââ La Caixa Foundation Health Research consortium (HR20-00075). The CNIC is supported by the Instituto de
Salud Carlos III (ISCIII), the MCIN and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (grant
CEX2020-001041-S). We acknowledge ALBA for provision of
synchrotron radiation facilities. We would like to thank Dr
Marc Malfois for assistance in using BL11-NCD beamline, and
Unai CossıŽo and Daniel Padro for help with image analysis.S
RANKL acts directly on RANK-expressing prostate tumor cells and mediates migration and expression of tumor metastasis genes
BACKGROUND Metastases to bone are a frequent complication of human prostate cancer and result in the development of osteoblastic lesions that include an underlying osteoclastic component. Previous studies in rodent models of breast and prostate cancer have established that receptor activator of NF-ÎB ligand (RANKL) inhibition decreases bone lesion development and tumor growth in bone. RANK is essential for osteoclast differentiation, activation, and survival via its expression on osteoclasts and their precursors. RANK expression has also been observed in some tumor cell types such as breast and colon, suggesting that RANKL may play a direct role on tumor cells. METHODS Male CB17 severe combined immunodeficient (SCID) mice were injected with PC3 cells intratibially and treated with either PBS or human osteprotegerin (OPG)-Fc, a RANKL antagonist. The formation of osteolytic lesions was analyzed by X-ray, and local and systemic levels of RANKL and OPG were analyzed. RANK mRNA and protein expression were assessed on multiple prostate cancer cell lines, and events downstream of RANK activation were studied in PC3 cells in vitro. RESULTS OPG-Fc treatment of PC3 tumor-bearing mice decreased lesion formation and tumor burden. Systemic and local levels of RANKL expression were increased in PC3 tumor bearing mice. PC3 cells responded to RANKL by activating multiple signaling pathways which resulted in significant changes in expression of genes involved in osteolysis and migration. RANK activation via RANKL resulted in increased invasion of PC3 cells through a collagen matrix. CONCLUSION These data demonstrate that host stromal RANKL is induced systemically and locally as a result of PC3 prostate tumor growth within the skeleton. RANK is expressed on prostate cancer cells and promotes invasion in a RANKL-dependent manner. Prostate 68: 92â104, 2008. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57344/1/20678_ftp.pd
Properties of Cosmic Shock Waves in Large Scale Structure Formation
We have examined the properties of shock waves in simulations of large scale
structure formation for two cosmological scenarios (a SCDM and a LCDM with
Omega =1). Large-scale shocks result from accretion onto sheets, filaments and
Galaxy Clusters (GCs) on a scale of circa 5 Mpc/h in both cases. Energetic
motions, both residual of past accretion history and due to current asymmetric
inflow along filaments, generate additional, common shocks on a scale of about
1 Mpc/h, which penetrate deep inside GCs. Also collisions between substructures
inside GCs form merger shocks. Consequently, the topology of the shocks is very
complex and highly connected. During cosmic evolution the comoving shock
surface density decreases, reflecting the ongoing structure merger process in
both scenarios. Accretion shocks have very high Mach numbers (10-10^3), when
photo-heating of the pre-shock gas is not included. The typical shock speed is
of order v_{sh}(z) =H(z)lambda_{NL}(z), with lambda_{NL}(z) the wavelength
scale of the nonlinear perturbation at the given epoch. However, the Mach
number for shocks occuring within clusters is usually smaller (3-10), due to
the fact that the intracluster gas is already hot. Statistical fits of shock
speed around GCs as a function of GCs temperature give power-law's in accord
with 1-D predictions. However, a very different result is obtained for fits of
the shock radius, reflecting the very complex shock structures forming in 3-D
simulations. The in-flowing kinetic energy across such shocks, giving the power
available for cosmic-ray acceleration, is comparable to the cluster X-ray
luminosity emitted from a central region of radius 0.5 Mpc/h. Considering their
large size and long lifetimes, those shocks are potentially interesting sites
for cosmic-ray acceleration, if modest magnetic fields exist within them.Comment: 20 Pages, 11 figures, ApJ in press. Complete set of full resolution
figures available at http://www.msi.umn.edu:80/Projects/twj/figures.tar.g
Density profiles of dark matter haloes: diversity and dependence on environment
(Abridged) We study the outer density profiles of dark matter haloes
predicted by a generalized secondary infall model and observed in a N-body
cosmological simulation of a \Lambda CDM model. We find substantial systematic
variations in shapes and concentrations of the halo profiles as well as a
strong correlation of the profiles with the environment. In the N-body
simulation, the average outer slope of the density profiles, \beta (\rho\propto
r^{-\beta}), of isolated haloes is \approx 2.9; 68% of these haloes have values
of \beta between 2.5 and 3.8. Haloes in dense environments of clusters are more
concentrated and exhibit a broad distribution of \beta with values larger than
for isolated haloes . Contrary to what one may expect, the haloes contained
within groups and galaxy systems are less concentrated and have flatter outer
density profiles than the isolated haloes. The concentration decreases with
M_h, but its scatter for a given mass is substantial. The mass and circular
velocity of the haloes are strongly correlated: M_h \propto V_m^{\alpha} with
\alpha ~ 3.3 (isolated) and ~3.5 (haloes in clusters). For M_h=10^12M_sun the
rms deviations from these relations are \Delta logM_h=0.12 and 0.18,
respectively. Approximately 30% of the haloes are contained within larger
haloes or have massive companions (larger than ~0.3 the mass of the current
halo) within 3 virial radii. The remaining 70% of the haloes are isolated
objects. The distribution of \beta as well as the concentration-mass and
M_h-V_m relations for the isolated haloes agree very well with the predictions
of our seminumerical approach which is based on a generalization of the
secondary infall model and on the extended Press-Schechter formalism.Comment: 14 pages, 11 figures included, uses mn.sty, accepted by MNRAS. Minor
modifications, new and updated reference
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