姬松茸多糖对糖尿病大鼠脑组织保护作用及其机制

目的:探讨姬松茸多糖对糖尿病大鼠脑组织保护作用及其作用机制。方法:将Wistar大鼠随机分为5组,A:正常对照组;B:模型组;C:2%姬松茸多糖组;D:4%姬松茸多糖组;E:8%姬松茸多糖组。8周后,HE染色观察脑组织病理变化,琼脂糖凝胶电泳检测细胞凋亡,RT-PCR观察p53基因的表达。结果:与模型组相比,姬松茸多糖治疗组脑组织形态明显改善,脑组织细胞凋亡量明显减少,p53基因的表达明显减少。结论:姬松茸多糖对糖尿病大鼠脑组织有明显保护作用,其机制可能与抑制细胞凋亡及p53基因的表达有关。     

Improvement and induction property of radiation-responsive promoter through DNA shuffling of 5′-flanking regions of the human p21 gene

A promoter that augments gene expression in response to stimulation of ionizing radiation would be a desired tool for radiogenetic therapy, a combination of radiotherapy and gene therapy. Although various promoters occurring naturally or artificially have been used for researches, one showing higher reactivity to ionizing radiation is desirable. In the present study, we attempted to improve a radiation-responsive promoter of the p21 through a technique called DNA shuffling. A library of DNA fragments was constructed by re-ligation of randomly digested promoter fragments and improved promoters were chosen out of the library. We repeated this process twice to obtain a promoter showing 2.6-fold better reactivity to ionizing radiation compared with its parent, p21 promoter after 10 Gy γ-ray irradiation. Nucleotide sequence analyses revealed that the obtained promoter was densely packed with some of the cis-acting elements including binding sites for p53, NF-κB, NRF-2, AP-1 and NF-Y more than p21 promoter. In addition, it was shown that its induction by ionizing radiation was dependent upon p53 status of a cell line, suggesting that the promoter retained properties of the p21 promoter. This technique is simple and efficient to improve a promoter responsive to other stimulus of interest besides IR.     

基于深度学习的布匹疵点检测方法

为快速、准确检测布匹疵点,提出以深度学习目标检测框架YOLOv4为基础的布匹疵点检测方式,首先将5种常见疵点图像(吊经、百脚、结点、破洞、污渍)进行预处理,然后将图像输入到YOLOv4算法中进行分类。YOLOv4采用CSPDarknet53作为主干网络提取疵点特征,SPP模块、FPN+PAN的方式作为Neck层进行深层疵点特征提取,预测层采用3种尺度预测方式,对不同大小的疵点进行检测。研究结果表明:经600个测试集样本的验证,该方法对疵点图像的检测准确率达95%,检测单张疵点图像的速率为33 ms。与SSD、Faster R-CNN、YOLOv3方法进行比较,采用YOLOv4方法准确率更高,速度更快。     

A survey of singular curves in sub-Riemannian geometry

Sub-Riemannian geometry is the geometry of a distribution ofk-planes on an-dimensional manifold with a smoothly varying inner product on thek-planes. Singular curves are singularities of the space of paths tangent to the distribution and joining two fixed points. This survey is devoted to the singular curves, which can be length minimizing geodesics, independent of the choice of inner product.     

anti-Benzo[a]pyrene-7,8-diol-9,10-epoxide Treatment Increases Levels of the Proteins p53 and p21WAF1 in the Human Mammary Carcinoma Cell Line MCF-7

The tumor suppressor p53 is involved in the recognition of DNA damage induced by radiation and chemicals. The effect of polycyclic hydrocarbons on p53 was investigated by treating MCF-7 cells with anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (B[a]PDE), an ultimate carcinogenic metabolite of benzo[a]pyrene. Western blotting of lysates with antibody mAb1801 showed that B[a]PDE doses of 0.1 to 0.5 μM caused detectable increases in p53 protein. In cells treated with 0.3 μM B[a]PDE, p53 protein levels increased by 2 hours after treatment, reached a maximum between 8 and 24 hours and returned to control value by 120 hours after treatment. Levels of p21^WAF1 protein increased by 8 hours after treatment, reached a maximum by 48 hours and returned to control value by 168 hours after treatment. B[a]PDE-DNA adducts were quantitated by [γ-³³P]ATP postlabeling and separation on reverse-phase HPLC. Adduct levels dropped rapidly between 2 and 24 hrs after treatment (48 to 15 pmol/mg DNA), and subsequently decreased more slowly (12 pmol/mg DNA at 48 hrs to 3 at 168 hrs). By 96 hours after treatment, p53 protein levels were comparable to those from untreated controls, although a low level of B[a]PDE-DNA adducts remained. Cells treated with B[a]PDE also incorporated significantly less [³H]thymidine into DNA than did untreated cells for at least 24 hours after treatment. These results provide preliminary evidence that B[a]PDE-induced DNA damage is recognized by a p53-dependent signal transduction pathway and suggest that cell cycle arrest occurs during the repair of the majority of the B[a]PDE-DNA adducts.     

Vitamin D and Death by Sunshine

Exposure to sunlight is the major cause of skin cancer. Ultraviolet radiation (UV) from the sun causes damage to DNA by direct absorption and can cause skin cell death. UV also causes production of reactive oxygen species that may interact with DNA to indirectly cause oxidative DNA damage. UV increases accumulation of p53 in skin cells, which upregulates repair genes but promotes death of irreparably damaged cells. A benefit of sunlight is vitamin D, which is formed following exposure of 7-dehydrocholesterol in skin cells to UV. The relatively inert vitamin D is metabolized to various biologically active compounds, including 1,25-dihydroxyvitamin D3. Therapeutic use of vitamin D compounds has proven beneficial in several cancer types, but more recently these compounds have been shown to prevent UV-induced cell death and DNA damage in human skin cells. Here, we discuss the effects of vitamin D compounds in skin cells that have been exposed to UV. Specifically, we examine the various signaling pathways involved in the vitamin D-induced protection of skin cells from UV.     

An Estimate for the Entropy of Hamiltonian Flows

In this paper, we present a generalization to Hamiltonian flows on symplectic manifolds of the estimate proved by Ballmann and Wojtkovski in [4] for the dynamical entropy of the geodesic flow on a compact Riemannian manifold of nonpositive sectional curvature. Given such a Riemannian manifold M, Ballmann and Wojtkovski proved that the dynamical entropy h _μ of the geodesic flow on M satisfies the inequalitywhere v is a unit vector in T _p M if p is a point in M, SM is the unit tangent bundle on M, K(v) is defined as , where is the Riemannian curvature of M, and μ is the normalized Liouville measure on SM. We consider a symplectic manifold M of dimension 2n, and a compact submanifold N of M, given by the regular level set of a Hamiltonian function on M; moreover, we consider a smooth Lagrangian distribution on N, and we assume that the reduced curvature of the Hamiltonian vector field with respect to the distribution is non-positive. Then we prove that under these assumptions, the dynamical entropy h _μ of the Hamiltonian flow with respect to the normalized Liouville measure on N satisfies      

Synthesis of thin amine-functionalized MIL-53 membrane with high hydrogen permeability

A thin amine-functionalized MIL-53 membrane with high permeability of hydrogen was successfully prepared on a porous α-Al₂O₃ support by using the secondary growth method. Seeded α-Al₂O₃ supports were prepared by a dip-coating technique. In contrast, a discontinuous membrane was obtained by using unseeded support under the same synthesis conditions, implying that the seeds play the key role in the formation of compact membranes. The resulting compact membranes were measured by X-ray diffraction (XRD), scanning electron microscopy (SEM) and single gas permeation testing. Results showed that the thickness of the as-prepared membrane was around 2 ∼ 4 μm. Hydrogen permeance of the as-prepared membrane reached a remarkable value of 1.5 × 10⁻⁵ mol m⁻² s⁻¹·Pa⁻¹ at room temperature under a 0.1 MPa pressure drop. The ideal H₂/CO₂ selectivity was found to be 4.4. In addition, the influence of seeding solution on the membrane performance was investigated. We found that the membrane permeance decreased and the ideal selectivity increased when the seeding solution content was increased.