Human interleukin-24 (IL-24) has been found recently to play a tumor-suppressor role in a variety of tumors, including gliomas. However, the exact mechanism of glioma tumor suppression by IL-24 remains unclear. We collected by surgery 30 gliomas at different grades and evaluated IL-24 and double-stranded RNA-activated protein kinase (PKR) expression using fluorescence quantitative real-time PCR and immunohistochemical techniques. Two human glioma cell lines, U87 and U251, were transfected with Ad5F35-IL24 via recombinant adenovirus-mediated gene transfer and apoptosis, as well as PKR and eIF-2α expression analyzed. The results showed that IL-24 and PKR expression decreased with increasing tumor grade. Compared with cells of the control groups, Ad5F35-IL24-infected U87 and U251 cells exhibited a significantly increased apoptosis and elevated PKR, eIF-2α, p-PKR, and p-eIF-2α levels, while the expression of Bcl-2 was decreased. Finally, IL-24 also sensitized apoptosis of glioma cells to temozolomide (TMZ). This study indicates that IL-24 upregulates expression and activation of PKR, further increasing expression and activation of eIF-2α, and decreasing Bcl-2 to promote apoptosis. IL-24 also increases chemosensitivity of glioma cells to TMZ.
It is of great significance for urban planning and management to identify the influencing factors on population size. We collect the data of resident population and its influencing factors in China four municipalities from 1997 to 2016 to establish a fixed effect model. The urban population size and its influencing factors are analyzed from the angle of cost and income. The results suggest that the wage level, the development of the second and third industries, and the medical level are the main income factors to promote population growth. In addition, the intensity of environmental pollution is the main cost factor to restrain population growth. However, there is a significant positive relationship between the real estate price and the urban population size, perhaps the population size growth causes the real estate prices rise.
The spatial distribution of the urban agglomeration population has changed increasingly in rapid urbanization. It affects the urban economy, environment, transportation, and so on. Therefore, it is of great significance to understand the changes in the spatial distribution of population in urban agglomerations. This study uses methods such as population center of gravity migration and Gini coefficient to explore changes in the spatial distribution of urban populations. The study found that the population center of the Beijing-Tianjin-Hebei urban agglomeration first migrated toward Beijing and then away from Beijing. During this process, the Gini coefficient increased from 0.62 to 0.64 and then decreased to 0.58, indicating that the population balance of the urban agglomeration first increased and then decreased. This result is consistent with the conclusion that we have established a simulated urban agglomeration for theoretical derivation. That is: in the early stage of urban agglomeration development, the population migrated to the central city; as the population of the central city became saturated, the urban agglomeration developed to a mature stage, and the population began to migrate to the peripheral cities. In this process, the population distribution center of urban agglomeration gradually shifted from central towns to peripheral towns. The degree of equilibrium in the spatial distribution of population has undergone an inverted u-shaped transition from non-equilibrium to equilibrium.
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