1,425 research outputs found
Targetable Multi-Drug Nanoparticles for Treatment of Glioblastoma with Neuroimaging Assessment
Indiana University-Purdue University Indianapolis (IUPUI)Glioblastoma (GBM) is a deadly, malignant brain tumor with a poor long-term
prognosis. The current median survival is approximately fifteen to seventeen months
with the standard of care therapy which includes surgery, radiation, and chemotherapy.
An important factor contributing to recurrence of GBM is high resistance of
GBM cancer stem cells (CSCs), for which a systemically delivered single drug approach
will be unlikely to produce a viable cure. Therefore, multi-drug therapies
are needed. Currently, only temozolomide (TMZ), which is a DNA alkylator, affects
overall survival in GBM patients. CSCs regenerate rapidly and over-express a methyl
transferase which overrides the DNA-alkylating mechanism of TMZ, leading to drug
resistance. Idasanutlin (RG7388, R05503781) is a potent, selective MDM2 antagonist
that additively kills GBM CSCs when combined with TMZ. By harnessing the
strengths of nanotechnology, therapy can be combined with diagnostics in a truly theranostic manner for enhancing personalized medicine against GBM. The goal of this
thesis was to develop a multi-drug therapy using multi-functional nanoparticles (NPs)
that preferentially target the GBM CSC subpopulation and provide in vivo preclinical
imaging capability. Polymer-micellar NPs composed of poly(styrene-b-ethylene
oxide) (PS-b-PEO) and poly(lactic-co-glycolic) acid (PLGA) were developed investigating
both single and double emulsion fabrication techniques as well as combinations
of TMZ and RG7388. The NPs were covalently bound to a 15 base-pair CD133 aptamer
in order to target a specific epitope on the CD133 antigen expressed on the
surface of GBM CSC subpopulation. For theranostic functionality, the NPs were also labelled with a positron emission tomography (PET) radiotracer, zirconium-89
(89Zr). The NPs maintained a small size of less than 100 nm, a relatively neutral
charge and exhibited the ability to produce a cytotoxic effect on CSCs. There was a
slight increase in killing with the aptamer-bound NPs compared to those without a
targeting agent. This work has provided a potentially therapeutic option for GBM
specific for CSC targeting and future in vivo biodistribution studies
A Large-Diameter Hollow-Shaft Cryogenic Motor Based on a Superconducting Magnetic Bearing for Millimeter-Wave Polarimetry
In this paper we present the design and measured performance of a novel
cryogenic motor based on a superconducting magnetic bearing (SMB). The motor is
tailored for use in millimeter-wave half-wave plate (HWP) polarimeters, where a
HWP is rapidly rotated in front of a polarization analyzer or
polarization-sensitive detector. This polarimetry technique is commonly used in
cosmic microwave background (CMB) polarization studies. The SMB we use is
composed of fourteen yttrium barium copper oxide (YBCO) disks and a contiguous
neodymium iron boron (NdFeB) ring magnet. The motor is a hollow-shaft motor
because the HWP is ultimately installed in the rotor. The motor presented here
has a 100 mm diameter rotor aperture. However, the design can be scaled up to
rotor aperture diameters of approximately 500 mm. Our motor system is composed
of four primary subsystems: (i) the rotor assembly, which includes the NdFeB
ring magnet, (ii) the stator assembly, which includes the YBCO disks, (iii) an
incremental encoder, and (iv) the drive electronics. While the YBCO is cooling
through its superconducting transition, the rotor is held above the stator by a
novel hold and release mechanism (HRM). The encoder subsystem consists of a
custom-built encoder disk read out by two fiber optic readout sensors. For the
demonstration described in this paper, we ran the motor at 50 K and tested
rotation frequencies up to approximately 10 Hz. The feedback system was able to
stabilize the the rotation speed to approximately 0.4%, and the measured rotor
orientation angle uncertainty is less than 0.15 deg. Lower temperature
operation will require additional development activities, which we will
discuss
Vertical Force-deflection Characteristics of a Pair of 56-inch-diameter Aircraft Tires from Static and Drop Tests with and Without Prerotation
The vertical force-deflection characteristics were experimentally determined for a pair of 56-inch-diameter tires under static and drop-test conditions with and without prerotation. For increasing force, the tires were found to be least stiff for static tests, almost the same as for the static case for prerotation drop tests as long as the tires remain rotating, and appreciably stiffer for drop tests without prerotation
- …