927 research outputs found
Cdc7/ASK kinase as a novel target for anti-cancer drug development programmes
Targeting Cdc7, a kinase essential for DNA replication initiation, results in potent
cancer cell killing. Cancer cells in which CDC7 is silenced by RNAi enter an abortive
S phase followed by apoptosis due to loss of a functioning DNA replication origin
activation checkpoint. This checkpoint prevents normal cells from entering S phase
(reversible G1 arrest) if the DNA replication initiation machinery is perturbed. The
pre-clinical anti-cancer effects of CDC7 silencing have highlighted this kinase as an
important target for new drug development. Expanding on published reports, I
performed further target validation using molecular tools generated in the work of this
thesis, including an affinity-purified antibody to the Cdc7 regulator ASK and
functional recombinant Cdc7/ASK kinase complex. Making use of fibroblast and
HL60 tissue culture model systems, I show that Cdc7 and ASK are amongst a group
of essential replication initiation factors that are tightly downregulated to suppress
proliferative capacity during exit from cycle into quiescent and differentiated states.
This finding is further supported by low expression levels in normal liver and oral
squamous epithelium and the lack of Mcm2 phosphorylation at serine 53, a well
known Cdc7 target. In liver carcinoma and oral squamous cell carcinoma, on the
contrary, the majority of cancer cells are expressing Cdc7 and ASK and show Mcm2
phosphorylation at Ser-53. Thus it can be postulated that Cdc7 inhibitors should
selectively kill cancer cells, while normal proliferating cells are reversibly arresting in
G1 and quiescent and differentiated cell populations are not affected due to
downregulation of the target protein. To screen for compounds that selectively inhibit
Cdc7, I developed a sensitive in vitro kinase assay and contributed to the successful
transfer of this assay to a high-throughput screening platform and the generation of a
structural model of the Cdc7 kinase domain allowing in silico predictions of the most
potent inhibitors. On completion of the work for this thesis, the HTS assay and
structural model fromed the core of an ongoing drug discovery programme run by
Cancer Research Technology. Two series of novel, selective small molecule inhibitors
which exhibit low nM activity against Cdc7 and cellular efficacy (apoptosis) have
been developed and are currently being tested in mouse xenograft models. The work
presented in this thesis provides a strong rationale for targeting the DNA replication
initiation pathway, and in particular Cdc7. Future intend to treat clinical trials will
establish the potential of pharmacological Cdc7 inhibitors for selective cancer cell
killing in patients
RELATIONSHIP BETWEEN UREA DECOMPOSITION AND CELL CLASSES OF RESERVOIR PHYTOPLANKTON IN THE NORTH HAN RIVER SYSTEM
The influence of natural phytoplankton cell classes upon the response of urea decomposition was investigated in four reservoirs in the North Han River System. The decomposition rate of urea was 0.3 to 29.4 μ mol urea・m⁻³・hr.⁻¹ in the light and 0.2 to 14.9 μ mol urea・m⁻³・hr.⁻¹ in the dark. Much higher decomposition rates were observed at the eutrophic stations in Lake Euiam. The urea decomposition in the smaller fraction (25 μm). No differences in the ratios of urea decomposition to chlorophyll-a or photosynthesis among three fractions were observed. This might be mainly due to the difference in the standing crop of phytoplankton. These trends were no different between sampling areas and reservoirs. The greater part of urea decomposition was the phase of CO₂ liberation rate into the water. Eight to 50% of the urea decomposition was incorporated into the particulate phase in the light, but this was much lower in the dark. The results of the present study indicate that urea in reservoirs decomposes by phytoplankton rather than bacteria and the phytoplankton would be competitive to bacteria.Article信州大学理学部付属諏訪臨湖実験所報告 7: 31-40(1991)departmental bulletin pape
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Comparison of calculated neutral beam shine through with measured shine-through in DIII-D
A comparison of the calculated shine through of neutral particle beams in the DIII-D plasma to measured values inferred from the target temperature rise is reported. This provides an opportunity to verify the shine through calculations and makes them more reliable in those cases where the shine through can not be measured. The DIII-D centerpost neutral beam target tiles are safe-guarded against excessive beam shine-through by pyrometry and thermocouple (TC) arrays on the tiles. Shine-through beam power is calculated from the measured temperature changes reported by the target tile TC array. These measurements are performed at the beginning of each operational year at DIII-D. Theoretically, the beam energy deposited into the plasma can be expressed as a function of the change in beam density. Neutral beam energy deposition in plasma (of known density) is inferred by comparing the results of a series of shine-through measurements for the 1997 campaign at DIII-D to the expected shine-through given by theory
Approximation of excitonic absorption in disordered systems using a compositional component weighted CPA
Employing a recently developed technique of component weighted two particle
Green's functions in the CPA of a binary substitutional alloy we
extend the existing theory of excitons in such media using a contact potential
model for the interaction between electrons and holes to an approximation which
interpolates correctly between the limits of weak and strong disorder. With our
approach we are also able to treat the case where the contact interaction
between carriers varies between sites of different types, thus introducing
further disorder into the system. Based on this approach we study numerically
how the formation of exciton bound states changes as the strengths of the
contact potentials associated with either of the two site types are varied
through a large range of parameter values.Comment: 27 pages RevTeX (preprint format), 13 Postscript figure file
The effect of school bag design and load on spinal posture during stair use by children
This is an Accepted Manuscript of an article published by Taylor & Francis in Ergonomics on 22/11/2011, available online: http://dx.doi.org/10.1080/00140139.2011.615415.Thirteen male children ascending and descending stairs with loads that equalled 0%, 10%, 15% and 20% of their body weight were the subject of our research: the boys were wearing an asymmetrical single-strap athletic bag or a symmetrical double-strap backpack during our experiments with them. The maximum spinal tilt to the loading side and to the support side, and the range of spinal motions, were obtained by using a motion analysis system. Our results showed that symmetry of spinal posture was observed both when they ascended staircase with all loads and descended in a backpack. When carrying an athletic bag with 15% and 20% of their body weight while ascending the staircase, the lateral spinal tilt to the supporting side was significantly increased. We concluded that a symmetrical backpack with a load not exceeding 20% or an asymmetrical single-strap athletic bag with a load not exceeding 10% should be recommended for school children in order to promote safer staircase use. Statement of Relevance: Children carrying heavy school bags may develop spinal problems. This study suggested that when they are using stairs, a symmetrical backpack with a load within 20% body weight is acceptable for them. When they are carrying an asymmetrical single-strap athletic bag, the bag's weight should not exceed 10% of the body weight in order to avoid excessive spinal tilt
Comparative transcriptome analysis identified candidate genes for late leaf spot resistance and cause of defoliation in groundnut
Late leaf spot (LLS) caused by fungus Nothopassalora personata in groundnut is responsible for up to 50% yield loss. To dissect the complex nature of LLS resistance, comparative transcriptome analysis was performed using resistant (GPBD 4), susceptible (TAG 24) and a resistant introgression line (ICGV 13208) and identified a total of 12,164 and 9954 DEGs (differentially expressed genes) respectively in A- and B-subgenomes of tetraploid groundnut. There were 135 and 136 unique pathways triggered in A- and B-subgenomes, respectively, upon N. personata infection. Highly upregulated putative disease resistance genes, an RPP-13 like (Aradu.P20JR) and a NBS-LRR (Aradu.Z87JB) were identified on chromosome A02 and A03, respectively, for LLS resistance. Mildew resistance Locus (MLOs)-like proteins, heavy metal transport proteins, and ubiquitin protein ligase showed trend of upregulation in susceptible genotypes, while tetratricopeptide repeats (TPR), pentatricopeptide repeat (PPR), chitinases, glutathione S-transferases, purple acid phosphatases showed upregulation in resistant genotypes. However, the highly expressed ethylene responsive factor (ERF) and ethylene responsive nuclear protein (ERF2), and early responsive dehydration gene (ERD) might be related to the possible causes of defoliation in susceptible genotypes. The identified disease resistance genes can be deployed in genomics-assisted breeding for development of LLS resistant cultivars to reduce the yield loss in groundnut
Bubbling AdS Black Holes
We explore the non-BPS analog of `AdS bubbles', which are regular spherically
symmetric 1/2 BPS geometries in type IIB supergravity. They have regular
horizons and can be thought of as bubbling generalizations of non-extremal AdS
black hole solutions in five-dimensional gauged supergravity. Due to the
appearance of the Heun equation even at the linearized level, various
approximation and numerical methods are needed in order to extract information
about this system. We study how the vacuum expectation value and mass of a
particular dimension two chiral primary operator depend on the temperature and
chemical potential of the thermal Yang-Mills theory. In addition, the mass of
the bubbling AdS black holes is computed. As is shown numerically, there are
also non-BPS solitonic bubbles which are completely regular and arise from
continuous deformations of BPS AdS bubbles.Comment: 37 pages, 2 figure
From Fake Supergravity to Superstars
The fake supergravity method is applied to 5-dimensional asymptotically AdS
spacetimes containing gravity coupled to a real scalar and an abelian gauge
field. The motivation is to obtain bulk solutions with R x S^3 symmetry in
order to explore the AdS/CFT correspondence when the boundary gauge theory is
on R x S^3. A fake supergravity action, invariant under local supersymmetry
through linear order in fermion fields, is obtained. The gauge field makes
things more restrictive than in previous applications of fake supergravity
which allowed quite general scalar potentials. Here the superpotential must
take the form W(\phi) ~ exp(-k\phi) + c exp(2\phi/(3k)), and the only freedom
is the choice of the constant k. The fermion transformation rules of fake
supergravity lead to fake Killing spinor equations. From their integrability
conditions, we obtain first order differential equations which we solve
analytically to find singular electrically charged solutions of the Lagrangian
field equations. A Schwarzschild mass term can be added to produce a horizon
which shields the singularity. The solutions, which include "superstars", turn
out to be known in the literature. We compute their holographic parameters.Comment: 42 pages, 3 figure
The Development of a Microwave Radiometer for Use as a Highway Ice Detector
DOT-FH-11-9328The program objective was to develop a system capable of detecting snow, ice, frost, or slush over a highway bridge deck area greater than 4 x 2 feet (1.2 x 0.6 m) and generate a valid alarm signal to warn motorists of a hazard. The detection system selected was a microwave radiometer operating at 10 GHz which continuously samples a reference noise source and internal amplifier noise to provide measurement corrections of radiated power received from the road surface being observed. Principal radiometer components are: rectangular horn antenna; sensitive receiver; and signal processor/alarm unit. The successive program phases were: (1) design optimization and system tradeoffs; (2) breadboard model laboratory and field tests; and (3) prototype model design, fabrication and test. Test results on asphalt and concrete roadway simulators, as well as actual asphalt roads, correlated with previously published radiometric temperatures for similar surfaces. The following road conditions were detectable: dry/warm; dry/cold; wet; slush; ice layer (0.1 cm. minimum); and snow layer (1 cm. minimum). All road hazard detection objectives were met except for frost detection. Descriptions of recommended additional effort are presented, including detailed evaluation of the prototype model; advanced alarm logic; self-test techniques; and a scanning antenna to cover increased road areas
Cornerstones of Sampling of Operator Theory
This paper reviews some results on the identifiability of classes of
operators whose Kohn-Nirenberg symbols are band-limited (called band-limited
operators), which we refer to as sampling of operators. We trace the motivation
and history of the subject back to the original work of the third-named author
in the late 1950s and early 1960s, and to the innovations in spread-spectrum
communications that preceded that work. We give a brief overview of the NOMAC
(Noise Modulation and Correlation) and Rake receivers, which were early
implementations of spread-spectrum multi-path wireless communication systems.
We examine in detail the original proof of the third-named author
characterizing identifiability of channels in terms of the maximum time and
Doppler spread of the channel, and do the same for the subsequent
generalization of that work by Bello.
The mathematical limitations inherent in the proofs of Bello and the third
author are removed by using mathematical tools unavailable at the time. We
survey more recent advances in sampling of operators and discuss the
implications of the use of periodically-weighted delta-trains as identifiers
for operator classes that satisfy Bello's criterion for identifiability,
leading to new insights into the theory of finite-dimensional Gabor systems. We
present novel results on operator sampling in higher dimensions, and review
implications and generalizations of the results to stochastic operators, MIMO
systems, and operators with unknown spreading domains
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