441 research outputs found
Case report: Single-session double-Ilizarov lengthening technique in the treatment of a child with congenital fibular deficiency
BackgroundCongenital fibular deficiency is a rare disease with a broad spectrum of deformities. Associated anomalies complicate the symptoms of patients and, consequently, individualized treatments that aim at normal function and acceptable appearance.Case presentationWe present a case of congenital femoral and fibular shortening in the right lower limb with foot anomaly at school age. The patient underwent limb lengthening procedure in a single session on the right femur and tibia at the same time using a double-Ilizarov frame. The functional and cosmetic of his right lower extremity achieved a good outcome. Complications were minimal except for the superficial infection. Treatment lasted for 9.2 months, allowing for returning the patient to functional activity as soon as possible.ConclusionA satisfactory result was obtained with limb lengthening in a single session using double Ilizarov external fixators in a school-aged patient with congenital fibular deficiency
Diverse histone modifications on histone 3 lysine 9 and their relation to DNA methylation in specifying gene silencing
<p>Abstract</p> <p>Background</p> <p>Previous studies of individual genes have shown that in a self-enforcing way, dimethylation at histone 3 lysine 9 (dimethyl-H3K9) and DNA methylation cooperate to maintain a repressive mode of inactive genes. Less clear is whether this cooperation is generalized in mammalian genomes, such as mouse genome. Here we use epigenomic tools to simultaneously interrogate chromatin modifications and DNA methylation in a mouse leukemia cell line, L1210.</p> <p>Results</p> <p>Histone modifications on H3K9 and DNA methylation in L1210 were profiled by both global CpG island array and custom mouse promoter array analysis. We used chromatin immunoprecipitation microarray (ChIP-chip) to examine acetyl-H3K9 and dimethyl-H3K9. We found that the relative level of acetyl-H3K9 at different chromatin positions has a wider range of distribution than that of dimethyl-H3K9. We then used differential methylation hybridization (DMH) and the restriction landmark genome scanning (RLGS) to analyze the DNA methylation status of the same targets investigated by ChIP-chip. The results of epigenomic profiling, which have been independently confirmed for individual loci, show an inverse relationship between DNA methylation and histone acetylation in regulating gene silencing. In contrast to the previous notion, dimethyl-H3K9 seems to be less distinct in specifying silencing for the genes tested.</p> <p>Conclusion</p> <p>This study demonstrates in L1210 leukemia cells a diverse relationship between histone modifications and DNA methylation in the maintenance of gene silencing. Acetyl-H3K9 shows an inverse relationship between DNA methylation and histone acetylation in regulating gene silencing as expected. However, dimethyl-H3K9 seems to be less distinct in relation to promoter methylation. Meanwhile, a combination of epigenomic tools is of help in understanding the heterogeneity of epigenetic regulation, which may further our vision accumulated from single-gene studies.</p
Hilbert-Huang Transform analysis of quasi-periodic oscillations in MAXI J1820+070
We present time-frequency analysis, based on the Hilbert-Huang transform
(HHT), of the evolution on the low-frequency quasi-periodic oscillations
(LFQPOs) observed in the black hole X-ray binary MAXI J1820+070. Through the
empirical mode decomposition (EMD) method, we decompose the light curve of the
QPO component and measure its intrinsic phase lag between photons from
different energy bands. We find that the QPO phase lag is negative (low energy
photons lag behind high energy photons), meanwhile the absolute value of the
lag increases with energy. By applying the Hilbert transform to the light curve
of the QPO, we further extract the instantaneous frequency and amplitude of the
QPO. Compared these results with those from the Fourier analysis, we find that
the broadening of the QPO peak is mainly caused by the frequency modulation.
Through further analysis, we find that these modulations could share a common
physical origin with the broad-band noise, and can be well explained by the
internal shock model of the jet
Restriction landmark genomic scanning (RLGS) spot identification by second generation virtual RLGS in multiple genomes with multiple enzyme combinations.
BackgroundRestriction landmark genomic scanning (RLGS) is one of the most successfully applied methods for the identification of aberrant CpG island hypermethylation in cancer, as well as the identification of tissue specific methylation of CpG islands. However, a limitation to the utility of this method has been the ability to assign specific genomic sequences to RLGS spots, a process commonly referred to as "RLGS spot cloning."ResultsWe report the development of a virtual RLGS method (vRLGS) that allows for RLGS spot identification in any sequenced genome and with any enzyme combination. We report significant improvements in predicting DNA fragment migration patterns by incorporating sequence information into the migration models, and demonstrate a median Euclidian distance between actual and predicted spot migration of 0.18 centimeters for the most complex human RLGS pattern. We report the confirmed identification of 795 human and 530 mouse RLGS spots for the most commonly used enzyme combinations. We also developed a method to filter the virtual spots to reduce the number of extra spots seen on a virtual profile for both the mouse and human genomes. We demonstrate use of this filter to simplify spot cloning and to assist in the identification of spots exhibiting tissue-specific methylation.ConclusionThe new vRLGS system reported here is highly robust for the identification of novel RLGS spots. The migration models developed are not specific to the genome being studied or the enzyme combination being used, making this tool broadly applicable. The identification of hundreds of mouse and human RLGS spot loci confirms the strong bias of RLGS studies to focus on CpG islands and provides a valuable resource to rapidly study their methylation
Design & Optimization of the HV divider for JUNO 20-inch PMT
The Jiangmen Underground Observatory (JUNO) is a 20-kton liquid scintillator
detector that employs 20,000 20-inch photomultiplier tubes (PMTs) as photon
sensors, with 5,000 dynode-PMTs from HAMAMATSU Photonics K.K. (HPK), and 15,000
MCP-PMTs from North Night Vision Technology (NNVT) installed in pure water.
JUNO aims to provide long-lasting and the best performance operation by
utilizing a high-transparency liquid scintillator, high detection efficiency
PMTs, and specially designed electronics including water-proof potting for the
high voltage (HV) dividers of PMTs. In this paper, we present a summary of the
design and optimization of HV dividers for both types of 20-inch PMTs, which
includes collection efficiency, charge resolution, HV divider current, pulse
shape, and maximum amplitude restriction. We have developed and finalized four
schemes of the HV divider for different scenarios, including the final version
selected by JUNO. All 20,000 20-inch PMTs have successfully undergone
production and burning tests.Comment: 14pages,28figure
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