40 research outputs found
Study of Promoter Methylation Patterns of HOXA2, HOXA5, and HOXA6 and Its Clinicopathological Characteristics in Colorectal Cancer
Research on DNA methylation offers great potential for the identification of biomarkers that can be applied for accurately assessing an individual's risk for cancer. In this article, we try to find the ideal epigenetic genes involved in colorectal cancer (CRC) based on a CRC database and our CRC cohort. The top 20 genes with an extremely high frequency of hypermethylation in CRC were identified in the latest database. Remarkably, 3 HOXA genes were included in this list and ranked at the top. The percentage of methylation in the HOXA5, HOXA2, and HOXA6 genes in CRC were up to 67.62, 58.36, and 31.32%, respectively, and ranked first in CRC among all human tumor tissues. Paired colorectal tumor samples and adjacent non-tumor colorectal tissue samples and four CRC cell lines were selected for MethylTarget™ assays. The results demonstrated that CRC tissues and cells had a stronger methylation status around the 3 HOXA gene promoter regions compared with adjacent non-tumor colonic tissue samples. The Receiver operator characteristic curve (ROC) curves for HOXA genes show excellent diagnostic ability in distinguishing tissue from healthy individuals and CRC patients, especially for Stage I patients (AUC = 0.9979 in HOXA2, 0.9309 in HOXA5, and 0.8025 in HOXA6). An association analysis between the methylation pattern of HOXA genes and clinical indicators was performed and found that HOXA2 methylation was significantly associated with age, N, stage, M, lymphovascular invasion, perineural invasion, lymph node number. HOXA5 methylation was associated with age, T, M, stage, and tumor status, and HOXA6 methylation was associated with age and KRAS mutation. Notably, we found that the highest methylation of HOXA5 and HOXA2 occurs in the early stages of colorectal cancer tissues such as stage I, N0, MO, and non-invasive tissues. The methylation levels declined as tumors progressed. However, methylation level at any stage of the tumor was still significantly higher than in normal tissues (p < 0.0001). The mRNA of the 3 HOXA genes was downregulated in early tumor stages due to hypermethylation of CpG islands adjacent to the promoters of the genes. In addition, hypermethylation of HOXA5 and HOXA6 mainly occurred in patients < 60 years old and with MSI-L, MSS, CIMP.L and non-CIMP tumors. Together, this suggests that epigenetic silencing of 3 adjacent HOXA genes may be an important event in the progression of colorectal cancer
Parameter Estimation for Interrupted Sampling Repeater Jamming Based on ADMM
By repeatedly sampling, storing, and retransmitting parts of the radar signal, interrupted sampling repeater jamming (ISRJ) based on digital radio frequency memory (DRFM) can produce a train of secondary false targets symmetrical to the main false target, threatening to mislead or deceive the victim radar system. This paper proposes a computationally-effective method to estimating the parameters for ISRJ by resorting to the framework of alternating direction method of multipliers (ADMM). Firstly, the analytical form of pulse compression is derived. Then, for the purpose of estimating the parameters of ISRJ, the original problem is transformed into a nonlinear integer optimization model with respect to a window vector. On this basis, the ADMM is introduced to decompose the nonlinear integer optimization model into a series of sub-problems to estimate the width and number of ISRJ’s sample slices. Finally, the numerical simulation results show that, compared with the traditional time-frequency (TF) method, the proposed method exhibits much better performance in accuracy and stability
Large-scale synthesis and growth mechanism of single-crystal Se nanobelts
Single-crystal trigonal (t) Se nanobelts have been synthesized on a large scale by reducing SeO2 with glucose at 160 °C. Electron microscopy images show that the nanobelts are 80 nm in diameter, 25 nm in thickness, and up to several hundreds of micrometers in length. HRTEM images prove that the nanobelts are single crystals and preferentially grow along the [001] direction. The time-dependent TEM images revealed that the formation and growth of t-Se nanobelts were governed by a solid−solution−solid growth mechanism. The redox reaction directly produced amorphous (α) Se nanoparticles under hydrothermal conditions. t-Se nanobelts were formed by dissolution and recrystallization of the initial α-Se nanoparticles under the functional capping of poly(vinylpyrrolidone) (PVP). The nanobelts obtained exhibit a quantum size effect in optical properties, showing a blue shift of the band gap and direct transitions relative to the values of bulk t-Se
Upregulation of UCP2 Expression Protects against LPS-Induced Oxidative Stress and Apoptosis in Cardiomyocytes
Uncoupling protein 2 (UCP2) has a cardioprotective role under septic conditions, but the underlying mechanism remains unclear. This study aimed at investigating the effects of UCP2 on the oxidative stress and apoptosis of cardiomyocytes induced by lipopolysaccharide (LPS). First, LPS increased UCP2 expression in cardiomyocytes in a time-dependent manner. LPS increased the production of lactate dehydrogenase (LDH), reactive oxygen species (ROS), and malondialdehyde (MDA) and decreased the level of superoxide dismutase (SOD). However, UCP2 knockdown increased the LPS-induced cardiac injury and oxidative stress. In addition, LPS damaged the mitochondrial ultrastructure and led to the disruption of mitochondrial membrane potential (MMP), as well as the release of mitochondrial cytochrome c. UCP2 knockdown aggravated mitochondrial injury and the release of mitochondrial cytochrome c. LPS increased the protein levels of Bax and cleaved-caspase-3, decreased the protein level of Bcl-2, and upregulated the protein level of mitogen-activated protein kinase. However, upon UCP2 knockdown, the protein levels of Bax and cleaved-caspase-3 increased even further, and the protein level of Bcl-2 was further decreased. The protein level of phosphorylated p38 was also further enhanced. Thus, UCP2 protects against LPS-induced oxidative stress and apoptosis in cardiomyocytes
Structural evolution of the eastern segment of the Irtysh Shear Zone: implications for the collision between the East Junggar Terrane and the Chinese Altai Orogen (northwestern China)
The tectonic evolution of the Central Asian Orogenic Belt (CAOB) involved multiple episodes of arc accretions/collisions, but the reconstruction of these tectonic processes remains relatively poorly constrained. Evidence for a collision between the intra-oceanic island arc system of the East Junggar Terrane and the active margin of the Siberian Craton (Chinese Altai Orogen) is recorded in the eastern segment of the Irtysh Shear Zone (northwestern China). Field observations from the Qinghe area show that this segment of the Irtysh Shear Zone consists of four NW–SE sinistral mylonitic zones, and domains bounded by these mylonitic zones show variable fold patterns. In the northern part of the Irtysh Shear Zone (southern Chinese Altai Orogen), three generations of structures (D–D) are recognized. The earliest generation of foliation (S) is only recognized locally and is transposed to the orientation of the dominant D foliation (S). The latter is associated with a shallowly plunging stretching lineation, which is sub-parallel to the NW–SE hinge of D folds. These third-generation folds (D) show a steeply-dipping axial plane trending NW–SE. In the southern part of the Irtysh Shear Zone (northern East Junggar Terrane), the structural pattern is simpler and only involves a single generation of penetrative foliation (S). New U–Pb detrital zircon and Ar/Ar data provide constraints on the timing of collision and deformation. These results suggest that the collision occurred after the Early Carboniferous, with the timing of sinistral shearing constrained to the Early–Middle Permian. The combination of sinistral shearing and NW–SE D folds likely represents an episode of transpressional deformation, which was driven by oblique collision between the East Junggar Terrane and the Chinese Altai Orogen during the Early–Middle Permian. The occurrence of original sub-horizontal S foliation and associated orogen-parallel stretching lineation might indicate that following the initial collision (after the Early Carboniferous), the southern Chinese Altai Orogen was subjected to orogen-parallel extension. In a larger-scale context, sinistral kinematics along the Irtysh Shear Zone in northwestern China and northeastern Kazakhstan, together with coeval dextral strike-slip deformation farther south, might reflect an eastward escape of orogenic materials, possibly in response to the Permian convergence of the Siberian, Baltic, and Tarim cratons
Benzoic Acid Catalyzed Annulations of α‑Amino Acids and Aromatic Aldehydes Containing an <i>ortho</i>-Michael Acceptor: Access to 2,5-Dihydro‑1<i>H</i>‑benzo[<i>c</i>]Âazepines and 10,11-Dihydro‑5<i>H</i>‑benzo[<i>e</i>]ÂpyrroloÂ[1,2‑<i>a</i>]azepines
A novel
one-pot efficient synthesis of 2,5-dihydro-1<i>H</i>-benzoÂ[<i>c</i>]Âazepines and 10,11-dihydro-5<i>H</i>-benzoÂ[<i>e</i>]ÂpyrroloÂ[1,2-<i>a</i>]Âazepines from
α-amino acids and aromatic aldehydes containing
an <i>ortho</i>-Michael acceptor is reported via decarboxylative
annulations without metal catalysts in yields of 52–91%. Under
microwave irradiation, this protocol provides rapid access to polycyclic
ring systems (only 5 min in most cases)