1,719 research outputs found
Weighted Bergman kernels and virtual Bergman kernels
We introduce the notion of "virtual Bergman kernel" and apply it to the
computation of the Bergman kernel of "domains inflated by Hermitian balls", in
particular when the base domain is a bounded symmetric domain.Comment: 12 pages. One-hour lecture for graduate students, SCV 2004, August
2004, Beijing, P.R. China. V2: typo correcte
Self-Assembly of a Virus-Mimicking Nanostructure System for Efficient Tumor-Targeted Gene Delivery
This is the published version, also available here: http://dx.doi.org/10.1089/10430340252792594.Molecular therapy, including gene therapy, is a promising strategy for the treatment of human disease. However, delivery of molecular therapeutics efficiently and specifically to the target tissue remains a significant challenge. A human transferrin (Tf)-targeted cationic liposome-DNA complex, Tf-lipoplex, has shown high gene transfer efficiency and efficacy with human head and neck cancer in vitro and in vivo (Xu, L., Pirollo, K.F., Tang, W.H., Rait, A., and Chang, E.H. Hum. Gene Ther. 1999;10:2941-2952). Here we explore the structure, size, formation process, and structure-function relationships of Tf-lipoplex. We have observed Tf-lipoplex to have a highly compact structure, with a relatively uniform size of 50-90 nm. This nanostructure is novel in that it resembles a virus particle with a dense core enveloped by a membrane coated with Tf molecules spiking the surface. More importantly, compared with unliganded lipoplex, Tf-lipoplex shows enhanced stability, improved in vivo gene transfer efficiency, and long-term efficacy for systemic p53 gene therapy of human prostate cancer when used in combination with conventional radiotherapy. On the basis of our observations, we propose a multistep self-assembly process and Tf-facilitated DNA cocondensation model that may provide an explanation for the resultant small size and effectiveness of our nanostructural Tf-lipoplex system
Personal non-commercial use only
ABSTRACT. Objective. Studying statistical gene-gene interactions (epistasis) has been limited by the difficulties in performance, both statistically and computationally, in large enough sample numbers to gain sufficient power. Three large Immunochip datasets from cohort samples recruited in the United Kingdom, United States, and Sweden with European ancestry were used to examine epistasis in rheumatoid arthritis (RA). Methods. A full pairwise search was conducted in the UK cohort using a high-throughput tool and the resultant significant epistatic signals were tested for replication in the United States and Swedish cohorts. A forward selection approach was applied to remove redundant signals, while conditioning on the preidentified additive effects. Results. We detected abundant genome-wide significant (p < 1.0e-13) epistatic signals, all within the MHC region. These signals were reduced substantially, but a proportion remained significant (p < 1.0e-03) in conditional tests. We identified 11 independent epistatic interactions across the entire MHC, each explaining on average 0.12% of the phenotypic variance, nearly all replicated in both replication cohorts. We also identified non-MHC epistatic interactions between RA susceptible loci LOC100506023 and IRF5 with Immunochip-wide significance (p < 1.1e-08) and between 2 neighboring single-nucleotide polymorphism near PTPN22 that were in low linkage disequilibrium with independent interaction (p < 1.0e-05). Both non-MHC epistatic interactions were statistically replicated with a similar interaction pattern in the US cohort only. Conclusion. There are multiple but relatively weak interactions independent of the additive effects in RA and a larger sample number is required to confidently assign additional non-MHC epistasis
Preparation of intergrown P/O-type biphasic layered oxides as high-performance cathodes for sodium ion batteries
This study reports on the solid-state synthesis and characterization of novel quaternary P/O intergrown biphasic NaMnyNiFeTiO (y = 0.6, 0.55, 0.5, 0.45) cathode materials. Electrochemical tests reveal superior performance of the P/O biphasic materials in a sodium ion battery compared to the single P2 or O3 phases, proving the beneficial effect of the intergrowth of P2 and O3 materials. The nature of the P/O interface was studied by transmission electron microscopy. The analysis shows a semi-coherent interface grown along the a/b and c axes with local differences in the transition metal concentration along the interface between the two phases. EDX and EELS characterization revealed a charge compensation mechanism across the phase boundary based on variation of the transition element distribution, balancing the different sodium contents in the P and O phases. The results reported in this study provide a better understanding of P/O biphasic materials
Nesting-driven antiferromagnetic order in Kondo lattice CePd5Al2
We investigated the electronic structure of the antiferromagnetic Kondo
lattice CePd5Al2 using high-resolution angle-resolved photoemission
spectroscopy. The experimentally determined band structure of the conduction
electrons is predominated by the Pd 4d character. It contains multiple hole and
electron Fermi pockets, in good agreement with density functional theory
calculations. The Fermi surface is folded over Q0 = (0, 0, 1), manifested by
Fermi surface reconstruction and band folding. Our results suggest that Fermi
surface nesting drives the formation of antiferromagnetic order in CePd5Al2.Comment: 6 pages,3 figur
A fast method for large-scale isolation of phages from hospital sewage using clinical drug-resistant Escherichia coli
With the continued emergence of multi-drug resistant genes and drug-resistant bacteria, the functions and applications of traditional antibiotics are challenged. Thus, products that can be combined with existing antibiotics or replace them are of great interest to the research and medical communities. As a natural parasite of bacteria, phages have been reconsidered for use in treating super or drug-resistant bacterial infections. The main aim of this study was to isolate new phages from hospital sewage, especially those with broad-spectrum infectivity for the establishment of an Escherichia phage library. According to differences in their infection spectrum, bacteriophages were identified using a plaque method. In total, 18 E. coli phages were isolated from hospital sewage. The characteristics of the wide host spectrum E. coli bacteriophage E12P1 were further studied. Electronic micrographs indicated that phage E12P1 had a cubic symmetry and a long tail. The growth curve suggested the incubation time was 30 min, the burst phase was 20 min, and the burst size was 43. This plaque-forming method could be adopted to isolate E. coli phage easily, rapidly and in large quantities. Among the 18 isolated E. coli phages, 10 of them had a broad host range in E. coli and warrant further study.Key words: Escherichia coli phages, large-scale isolation, drug resistance, biological properties
Berberine Improves Glucose Metabolism in Diabetic Rats by Inhibition of Hepatic Gluconeogenesis
Berberine (BBR) is a compound originally identified in a Chinese herbal medicine Huanglian (Coptis chinensis French). It improves glucose metabolism in type 2 diabetic patients. The mechanisms involve in activation of adenosine monophosphate activated protein kinase (AMPK) and improvement of insulin sensitivity. However, it is not clear if BBR reduces blood glucose through other mechanism. In this study, we addressed this issue by examining liver response to BBR in diabetic rats, in which hyperglycemia was induced in Sprague-Dawley rats by high fat diet. We observed that BBR decreased fasting glucose significantly. Gluconeogenic genes, Phosphoenolpyruvate carboxykinase (PEPCK) and Glucose-6-phosphatase (G6Pase), were decreased in liver by BBR. Hepatic steatosis was also reduced by BBR and expression of fatty acid synthase (FAS) was inhibited in liver. Activities of transcription factors including Forkhead transcription factor O1 (FoxO1), sterol regulatory element-binding protein 1c (SREBP1) and carbohydrate responsive element-binding protein (ChREBP) were decreased. Insulin signaling pathway was not altered in the liver. In cultured hepatocytes, BBR inhibited oxygen consumption and reduced intracellular adenosine triphosphate (ATP) level. The data suggest that BBR improves fasting blood glucose by direct inhibition of gluconeogenesis in liver. This activity is not dependent on insulin action. The gluconeogenic inhibition is likely a result of mitochondria inhibition by BBR. The observation supports that BBR improves glucose metabolism through an insulin-independent pathway
The Hidden Nematic Fluctuations in the Triclinic (Ca0.85La0.15)10(Pt3As8)(Fe2As2)5 Superconductor Revealed by Ultrafast Optical Spectroscopy
We reported the quasiparticle relaxation dynamics of an optimally doped
triclinic iron-based superconductor
(CaLa)(PtAs)(FeAs) with bulk
= 30 K using polarized ultrafast optical pump-probe spectroscopy. Our results
reveal anisotropic transient reflectivity induced by nematic fluctuations
develops below 120 K and persists in the superconducting
states. Measurements under high pump fluence reveal three distinct, coherent
phonon modes at frequencies of 1.6, 3.5, and 4.7 THz, corresponding to
, , and modes, respectively. The high-frequency
mode corresponds to the -axis polarized vibrations of FeAs
planes with a nominal electron-phonon coupling constant
0.139 0.02. Our findings suggest that the superconductivity and
nematic state are compatible but competitive at low temperatures, and the
phonons play an important role in the formation of Cooper pairs in
(CaLa)(PtAs)(FeAs).Comment: 6 pages, 3 figures and Supplemental Material
Dirac semimetal PdTe2 temperature-dependent quasiparticle dynamics and electron-phonon coupling
Dirac semimetal PdTe2 single-crystal temperature-dependent ultrafast carrier
and phonon dynamics were studied using ultrafast optical pump-probe
spectroscopy. Two distinct carrier and coherent phonons relaxation processes
were identified in the 5 K - 300 K range. Quantitative analysis revealed a fast
relaxation process ({\tau}_f) occurring on a subpicosecond time scale which
originated from electron-phonon thermalization. This was followed by a slower
relaxation process ({\tau}_s) with a time scale of ~ 7-9.5 ps which originated
from phonon-assisted electron-hole recombination. Two significant vibrational
modes resolved at all measured temperatures and corresponded to Te atoms
in-plane (E_g), and out-of-plane (A_1g), motion. As temperature increased both
phonon modes softened markedly. A_1g mode frequency monotonically decreased as
temperature increased. Its damping rate remained virtually unchanged. As
expected, E_g decreased uniformly as temperatures rose. At temperatures above
80 K, there was insignificant change. Test results suggested that pure
dephasing played an important role in the relaxation processes. PdTe2 phonon is
thought responsible for its superconductive properties. Examining phonons
behavior should improve the understanding of its complex superconductivity.Comment: 6 pages, 4 figure
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