650 research outputs found
Gene transfer into the central nervous system using Herpes Simplex Virus-1 vectors
Manipulation of gene expression in developing or in mature central nervous systems (CNS) holds a promise for the resolution of many compelling neurobiological questions, including the feasibility of gene therapy to treat diseases of the brain. In this context, a number of viral vectors has been used in recent years to introduce and express genes into the CNS. This article discusses a gene transfer system based on the Herpes Simplex Virus-1 (HSV-1). We describe here the use of non-replicating, non-toxic HSV-1 vector, 8117/43, in a series of studies carried in our joint program. This vector proves further the utility of HSV-1 as a delivery vehicle to a number of distinct sites within the CNS
Assessment of viral and non-viral gene transfer into adult rat brains using HSV-1, calcium phosphate and PEI-based methods
CNS gene transfer could provide new approaches to the modelling of neurodegenerative
diseases and devising potential therapies. One such disorder is Parkinson’s
disease (PD), in which dysfunction of several different metabolic processes
has been implicated. Here we review the literature on gene transfer systems
based on herpes simplex virus type 1 (HSV-1) and non-viral
polyethyleneimine (PEI) and calcium phosphate nanoparticle methods. We also
assess the usefulness of various CNS gene delivery methods and present some
of our own data to exemplify such usefulness. Our data result from vectors
stereotaxically introduced to the substantia nigra (SN) of adult rats and evaluated
1 week and/or 1 month post injection using histochemical methods to assess
recombinant ß-galactosidase enzyme activity. Gene transfer using PEI or calcium
phosphate-mediated transfections was observed for both methods and PEI was
comparable to that of HSV-1 amplicon. Our data show that the amplicon delivery
was markedly increased when packaged with a helper virus and was similar
to the expression profile achieved with a full-size replication-defective HSV-1
recombinant (8117/43). We also examine whether PEI or HSV-1 amplicon-mediated
gene transfer could facilitate assessment of the biological effects induced
by a dominant negative FGF receptor-1 mutant to model the reduced FGF signalling
thought to occur in Parkinson’s disease
Can dark matter be a Bose-Einstein condensate?
We consider the possibility that the dark matter, which is required to
explain the dynamics of the neutral hydrogen clouds at large distances from the
galactic center, could be in the form of a Bose-Einstein condensate. To study
the condensate we use the non-relativistic Gross-Pitaevskii equation. By
introducing the Madelung representation of the wave function, we formulate the
dynamics of the system in terms of the continuity equation and of the
hydrodynamic Euler equations. Hence dark matter can be described as a
non-relativistic, Newtonian Bose-Einstein gravitational condensate gas, whose
density and pressure are related by a barotropic equation of state. In the case
of a condensate with quartic non-linearity, the equation of state is polytropic
with index . To test the validity of the model we fit the Newtonian
tangential velocity equation of the model with a sample of rotation curves of
low surface brightness and dwarf galaxies, respectively. We find a very good
agreement between the theoretical rotation curves and the observational data
for the low surface brightness galaxies. The deflection of photons passing
through the dark matter halos is also analyzed, and the bending angle of light
is computed. The bending angle obtained for the Bose-Einstein condensate is
larger than that predicted by standard general relativistic and dark matter
models. Therefore the study of the light deflection by galaxies and the
gravitational lensing could discriminate between the Bose-Einstein condensate
dark matter model and other dark matter models.Comment: 20 pages, 7 figures, accepted for publication in JCAP, references
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Classical big-bounce cosmology: dynamical analysis of a homogeneous and irrotational Weyssenhoff fluid
A dynamical analysis of an effective homogeneous and irrotational Weyssenhoff
fluid in general relativity is performed using the 1+3 covariant approach that
enables the dynamics of the fluid to be determined without assuming any
particular form for the space-time metric. The spin contributions to the field
equations produce a bounce that averts an initial singularity, provided that
the spin density exceeds the rate of shear. At later times, when the spin
contribution can be neglected, a Weyssenhoff fluid reduces to a standard
cosmological fluid in general relativity. Numerical solutions for the time
evolution of the generalised scale factor in spatially-curved models are
presented, some of which exhibit eternal oscillatory behaviour without any
singularities. In spatially-flat models, analytical solutions for particular
values of the equation-of-state parameter are derived. Although the scale
factor of a Weyssenhoff fluid generically has a positive temporal curvature
near a bounce, it requires unreasonable fine tuning of the equation-of-state
parameter to produce a sufficiently extended period of inflation to fit the
current observational data.Comment: 34 pages, 18 figure
HMG1A and PPARG are differently expressed in the liver of fat and lean broilers
The expression of nine functional candidates for QT abdominal fat weight and relative abdominal fat content was investigated by real-time polymerase chain reaction (PCR) in the liver, adipose tissue, colon, muscle, pituitary gland and brain of broilers. The high mobility group AT-hook 1 (HMG1A) gene was up-regulated in liver with a ratio of means of 2.90 (P ≤ 0.01) in the «fatty» group (relative abdominal fat content 3.5 ± 0.18%, abdominal fat weight 35.4 ± 6.09 g) relative to the «lean» group (relative abdominal fat content 1.9 ± 0.56%, abdominal fat weight 19.2 ± 5.06 g). Expression of this gene was highly correlated with the relative abdominal fat content (0.70, P ≤ 0.01) and abdominal fat weight (0.70, P ≤ 0.01). The peroxisome proliferator-activated receptor gamma (PPARG) gene was also up-regulated in the liver with a ratio of means of 3.34 (P ≤ 0.01) in the «fatty» group relative to the «lean» group. Correlation of its expression was significant with both the relative abdominal fat content (0.55, P ≤ 0.05) and the abdominal fat weight (0.57, P ≤ 0.01). These data suggest that the HMG1A and PPARG genes were candidate genes for abdominal fat deposition in chickens. Searching of rSNPs in regulatory regions of the HMG1A and PPARG genes could provide a tool for gene-assisted selection
Towards understanding of Nipah virus attachment protein assembly and the role of protein affinity and crowding for membrane curvature events.
Pathogenic viruses are a primary threat to our national security and to the health and economy of our world. Effective defense strategies to combat viral infection and spread require the development of understanding of the mechanisms that these pathogens use to invade the host cell. We present in this report results of our research into viral particle recognition and fusion to cell membranes and the role that protein affinity and confinement in lipid domains plays in membrane curvature in cellular fusion and fission events. Herein, we describe 1) the assembly of the G attachment protein of Nipah virus using point mutation studies to define its role in viral particle fusion to the cell membrane, 2) how lateral pressure of membrane bound proteins induce curvature in model membrane systems, and 3) the role of membrane curvature in the selective partitioning of molecular receptors and specific affinity of associated proteins
In-situ measurement of journal bearing lubricant viscosity by means of a novel ultrasonic measurement technique using matching layer
An ultrasonic viscometer was used to measure the circumferential viscosity variation in a journal bearing non-invasively. This sensing technique is based on the reflection of a shear wave at a solid-liquid boundary that depends on the viscosity of the liquid and the acoustic properties of the solid. Very little ultrasonic energy can propagate into the oil at a metal-oil interface because the acoustic mismatch is significant. Interleaving a matching layer between the metal and the lubricant enables accurate ultrasonic viscosity measurements [1] Schirru, M., Mills, R., Dwyer-Joyce, R., Smith, O., and Sutton, M. (2015). Viscosity Measurement in a Lubricant Film Using an Ultrasonically Resonating Matching Layer. Tribology Letters, 60(3) pp. 1–11.
[CrossRef], [Web of Science ®]
. This technique has been used to build a miniaturized ultrasonic viscometer that is accommodated inside a journal to obtain the circumferential viscosity profile. Four viscosity regions are identified due to the variations in the localized temperatures and loads. The results are compared with the isothermal solution of the Reynolds equations for hydrodynamic lubricated bearings. The ultrasonic viscometer locates the angle at which the maximum load occurs and the length of the loaded contact with good accuracy. Finally, the viscosity results are used to estimate the frictional power losses. It is shown that over 70% of the total losses in the journal bearing occur in the region where the load is maximum
Depletion-Driven Morphological Control of Bundled Actin Networks
The actin cytoskeleton is a semiflexible biopolymer network whose morphology
is controlled by a wide range of biochemical and physical factors. Actin is
known to undergo a phase transition from a single-filament state to a bundled
state by the addition of polyethylene glycol (PEG) molecules in sufficient
concentration. While the depletion interaction experienced by these biopolymers
is well-known, the effect of changing the molecular weight of the depletant is
less well understood. Here, we experimentally identify a phase transition in
solutions of actin from networks of filaments to networks of bundles by varying
the molecular weight of PEG polymers, while holding the concentration of these
PEG polymers constant. We examine the states straddling the phase transition in
terms of micro and macroscale properties. We find that the mesh size, bundle
diameter, persistence length, and intra-bundle spacing between filaments across
the line of criticality do not show significant differences, while the
relaxation time, storage modulus, and degree of bundling change between the two
states do show significant differences. Our results demonstrate the ability to
tune actin network morphology and mechanics by controlling depletant size, a
property which could be exploited to develop actin-based materials with
switchable rigidity.Comment: 22 pages, 10 figures. Authors James Clarke and Francis Cavanna
contributed equally; Changes: Added modeling work, extended dynamic light
scattering analysi
HIV, Hepatitis C, and Hepatitis B Infections and Associated Risk Behavior in Injection Drug Users, Kabul, Afghanistan
Behavior of injection drug users increases the risk for an HIV epidemic
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