70 research outputs found
Development of a “Universal” Phantom for Standardization of Chemical Exchange Saturation Transfer (CEST) MRI
https://openworks.mdanderson.org/sumexp22/1039/thumbnail.jp
From carbon nanotubes and silicate layers to graphene platelets for polymer nanocomposites
In spite of extensive studies conducted on carbon nanotubes and silicate layers for their polymer-based nanocomposites, the rise of graphene now provides a more promising candidate due to its exceptionally high mechanical performance and electrical and thermal conductivities. The present study developed a facile approach to fabricate epoxy–graphene nanocomposites by thermally expanding a commercial product followed by ultrasonication and solution-compounding with epoxy, and investigated their morphologies, mechanical properties, electrical conductivity and thermal mechanical behaviour. Graphene platelets (GnPs) of 3.5
Deep Learning for Automatic Detection and Segmentation from CT Angiography of Deep Inferior Epigastric Vascular Structures for Preoperative Planning of TRAM Flap Surgeries
https://openworks.mdanderson.org/sumexp23/1131/thumbnail.jp
Towards High-quality prostate MRI: Frequency and reasons for repeated and extra sequences in prostate MRI examinations
https://openworks.mdanderson.org/sumexp21/1152/thumbnail.jp
Structure-Based Peptide Inhibitor Design of Amyloid-β Aggregation
Many human neurodegenerative diseases are associated with amyloid fibril formation. Inhibition of amyloid formation is of importance for therapeutics of the related diseases. However, the development of selective potent amyloid inhibitors remains challenging. Here based on the structures of amyloid β (Aβ) fibrils and their amyloid-forming segments, we designed a series of peptide inhibitors using RosettaDesign. We further utilized a chemical scaffold to constrain the designed peptides into β-strand conformation, which significantly improves the potency of the inhibitors against Aβ aggregation and toxicity. Furthermore, we show that by targeting different Aβ segments, the designed peptide inhibitors can selectively recognize different species of Aβ. Our study developed an approach that combines the structure-based rational design with chemical modification for the development of amyloid inhibitors, which could be applied to the development of therapeutics for different amyloid-related diseases
Sandage-Loeb test for the new agegraphic and Ricci dark energy models
The Sandage-Loeb (SL) test is a unique method to explore dark energy at the
``redshift desert'' (), an era not covered by any other
dark energy probes, by directly measuring the temporal variation of the
redshift of quasar (QSO) Lyman- absorption lines. In this paper, we
study the prospects for constraining the new agegraphic dark energy (NADE)
model and the Ricci dark energy (RDE) model with the SL test. We show that,
assuming only a ten-year survey, the SL test can constrain these two models
with high significance.Comment: 14 pages, 5 figures; version for publication in Phys.Lett.
Theoretical Limits on Agegraphic Quintessence from Weak Gravity Conjecture
In this paper, we investigate the possible theoretical constraint on the
parameter of the agegraphic quintessence model by considering the
requirement of the weak gravity conjecture that the variation of the
quintessence scalar field should be less than the Planck mass
. We obtain the theoretical upper bound that is
inconsistent with the current observational constraint result
(95.4% CL). The possible implications of the tension between observational and
theoretical constraint results are discussed.Comment: 14 pages, 3 figure
A more general interacting model of holographic dark energy
So far, there have been no theories or observational data that deny the
presence of interaction between dark energy and dark matter. We extend
naturally the holographic dark energy (HDE) model, proposed by Granda and
Oliveros, in which the dark energy density includes not only the square of the
Hubble scale, but also the time derivative of the Hubble scale to the case with
interaction and the analytic forms for the cosmic parameters are obtained under
the specific boundary conditions. The various behaviors concerning the cosmic
expansion depend on the introduced numerical parameters which are also
constrained. The more general interacting model inherits the features of the
previous ones of HDE, keeping the consistency of the theory.Comment: 7 pages, 8 figures, references adde
Photochemical origin of SiC in the circumstellar envelope of carbon-rich AGB stars revealed by ALMA
Whether SiC is a parent species, that is formed in the photosphere or as
a by-product of high-temperature dust formation, or a daughter species, formed
in a chemistry driven by the photodestruction of parent species in the outer
envelope, has been debated for a long time. Here, we analyze the ALMA
observations of four SiC transitions in the CSEs of three C-rich AGB stars
(AI Vol, II Lup, and RAFGL 4211), and found that SiC exhibits an annular,
shell-like distribution in these targets, suggesting that SiC can be a
daughter species in the CSEs of carbon-rich AGB stars. The results can provide
important references for future chemical models.Comment: Accepted in Frontiers in Astronomy and Space Science
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Nicotinamide mononucleotide adenylyltransferase uses its NAD+ substrate-binding site to chaperone phosphorylated Tau.
Funder: Science and Technology Commission of Shanghai Municipality; FundRef: http://dx.doi.org/10.13039/501100003399Funder: Dr. John T. MacDonald Foundation; FundRef: http://dx.doi.org/10.13039/100010239Tau hyper-phosphorylation and deposition into neurofibrillary tangles have been found in brains of patients with Alzheimer's disease (AD) and other tauopathies. Molecular chaperones are involved in regulating the pathological aggregation of phosphorylated Tau (pTau) and modulating disease progression. Here, we report that nicotinamide mononucleotide adenylyltransferase (NMNAT), a well-known NAD+ synthase, serves as a chaperone of pTau to prevent its amyloid aggregation in vitro as well as mitigate its pathology in a fly tauopathy model. By combining NMR spectroscopy, crystallography, single-molecule and computational approaches, we revealed that NMNAT adopts its enzymatic pocket to specifically bind the phosphorylated sites of pTau, which can be competitively disrupted by the enzymatic substrates of NMNAT. Moreover, we found that NMNAT serves as a co-chaperone of Hsp90 for the specific recognition of pTau over Tau. Our work uncovers a dedicated chaperone of pTau and suggests NMNAT as a key node between NAD+ metabolism and Tau homeostasis in aging and neurodegeneration
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