Critical Analysis of 40 Years of Education Reform in Educational Leadership Preparation in China

The success of a principal often depends on the preparation quality. The United States attaches great importance to the cultivation of educational leadership, and has established various professional organizations to study and manage the cultivation of educational leadership, which has promoted the continuous improvement of the cultivation plan of American educational leadership. In the past 40 years of China’s reform and opening up, the preparation level of principals in primary and secondary schools has risen from undergraduate to postgraduate. However, at present, it still shows the importance of on-the-job training of principals in primary and secondary schools, while neglecting the research and reform of pre service education activities of educational leaders, which leads to the standardization and professionalism of preparation methods of educational leaders to be improved. Therefore, we can learn from the preparation experience of American, combine with the actual situation of China, attach great importance to the professional training of education leaders, carry out extensive relevant academic research, enhance the direction leading role of education value and social responsibility, systematically design the preparation program of education leaders, and truly build a diversified social support and promotion network, improve the preparation effect of educational leadership in an all-round way

Immobilization of EreB on Acid-Modified Palygorskite for Highly Efficient Degradation of Erythromycin

Erythromycin is one of the most commonly used macrolide antibiotics. However, its pollution of the ecosystem is a significant risk to human health worldwide. Currently, there are no effective and environmentally friendly methods to resolve this issue. Although erythromycin esterase B (EreB) specifically degrades erythromycin, its non-recyclability and fragility limit the large-scale application of this enzyme. In this work, palygorskite was selected as a carrier for enzyme immobilization. The enzyme was attached to palygorskite via a crosslinking reaction to construct an effective erythromycin-degradation material (i.e., EreB@modified palygorskite), which was characterized using FT-IR, SEM, XRD, and Brunauer–Emmett–Teller techniques. The results suggested the successful modification of the material and the loading of the enzyme. The immobilized enzyme had a higher stability over varying temperatures (25–65 °C) and pH values (6.5–10.0) than the free enzyme, and the maximum rate of reaction (Vmax) and the turnover number (kcat) of the enzyme increased to 0.01 mM min−1 and 169 min−1, respectively, according to the enzyme-kinetics measurements. The EreB@modified palygorskite maintained about 45% of its activity after 10 cycles, and degraded erythromycin in polluted water to 20 mg L−1 within 300 min. These results indicate that EreB could serve as an effective immobilizing carrier for erythromycin degradation at the industrial scale

Disturbance of the let-7/LIN28 double-negative feedback loop is associated with radio- and chemo-resistance in non-small cell lung cancer

<div><p>Radio- and chemo-resistance represent major obstacles in the therapy of non-small-cell lung cancer (NSCLC) and the underlying molecular mechanisms are not known. In the present study, during induction of radio- or chemo-resistance in NSCLC cells, dynamic analyses revealed that decreased expression of let-7 induced by irradiation or cisplatin resulted in increased expression of its target gene <i>LIN28</i>, and increased expression of LIN28 then contributed to further decreased expression of let-7 by inhibiting its maturation and biogenesis. Moreover, we showed that down-regulation of let-7 and up-regulation of LIN28 expression promoted resistance to irradiation or cisplatin by regulating the single-cell proliferative capability of NSCLC cells. Consequently, in NSCLC cells, let-7 and LIN28 can form a double-negative feedback loop through mutual inhibition, and disturbance of the let-7/LIN28 double-negative feedback loop induced by irradiation or chemotherapeutic drugs can result in radio- and chemo-resistance. In addition, low expression of let-7 and high expression of LIN28 in NSCLC patients was associated significantly with resistance to radiotherapy or chemotherapy. Therefore, our study demonstrated that disturbance of the let-7/LIN28 double-negative feedback loop is involved in the regulation of radio- and chemo-resistance, and that let-7 and LIN28 could be employed as predictive biomarkers of response to radiotherapy or chemotherapy in NSCLC patients.</p></div

Let-7 family miRNAs regulated radio- and chemo-resistance by targeting <i>LIN28</i>.

<p><b>(A)</b> Luciferase assays of let-7 targeting effects on <i>LIN28</i>. Mutations were generated in the <i>LIN28A</i> 3′-UTR and <i>LIN28B</i> 3′-UTR sequence in the complementary site for the seed region of let-7 as indicated. <b>(B)</b> mRNA and protein levels of LIN28 were decreased in A549/IR and A549/DDP cells after transfection of let-7 mimics and increased in A549 cells after transfection of let-7 inhibitors, as detected by RT-PCR and western blotting. <b>(C)</b> Overexpression of let-7 decreased resistance to irradiation in A549/IR cells or to cisplatin in A549/DDP cells significantly. <b>(D)</b> Inhibition of let-7 increased resistance to irradiation or cisplatin in A549 cells significantly (n = 3, *<i>P</i> < 0.05).</p

Expression of let-7 family miRNAs was down-regulated in radio- or chemo-resistant cells.

<p><b>(A)</b> Members of the let-7 family (schematic). <b>(B)</b> Down-regulation of expression of let-7 family miRNAs in microarray experiments was validated by RT-PCR (n = 3, *<i>P</i> < 0.05).</p

Let-7 and LIN28 were putative regulators of single-cell proliferative capability.

<p><b>(A)</b> Colony-formation assay of A549/IR and A549/DDP cells transfected with let-7 mimics or si-LIN28A. <b>(B)</b> Colony-formation assay of A549 cells transfected with let-7 inhibitors or LIN28A plasmids (n = 3, *<i>P</i> < 0.05).</p

LIN28 blocked let-7 maturation specifically.

<p><b>(A)</b> si-LIN28 increased the maturation of let-7 in A549/IR and A549/DDP cells and LIN28 plasmid decreased the maturation of let-7 in A549 cells, respectively. <b>(B)</b> Inhibition of LIN28 decreased resistance to irradiation in A549/IR cells or to cisplatin in A549/DDP cells significantly. <b>(C)</b> Overexpression of LIN28 increased resistance to irradiation or cisplatin in A549 cells significantly (n = 3, *<i>P</i> < 0.05).</p

Dynamic analyses of expression of let-7 and LIN28 during induction of radio- or chemo-resistance in A549 cells.

<p><b>(A)</b> To varying degrees, expression of let-7 miRNAs was down-regulated during induction of radio- or chemo-resistance. <b>(B)</b> To varying degrees, expression of LIN28A and LIN28B was up-regulated during induction of radio- or chemo-resistance.</p