Haojun Zhang

Aneuploidy with chromosome instability is a cancer hallmark. We studied chromosome 7 copy number variation in gliomas and in primary cultures derived from them. We found tumor heterogeneity with cells having Chr7-CNV commonly occurs in gliomas, with a higher percentage of cells in high-grade gliomas carrying more than 2 copies of Chr7, as compared to low-grade gliomas. Interestingly, all Chr7-aneuploid cell types in the parental culture of established glioma cell lines reappeared in single-cell-derived subcultures. We then characterized the biology of three syngeneic glioma cultures dominated by different Chr7-aneuploid cell types. We found phenotypic divergence for cells following Chr7 missegregation, which benefited overall tumor growth in vitro and in vivo. Mathematical modeling suggested the involvement of chromosome instability and interactions among cell subpopulations in restoring the optimal equilibrium of tumor cell types. Both our experimental data and mathematical modeling demonstrated that the complexity of tumor heterogeneity could be enhanced by the existence of chromosomes with structural abnormality, in addition to their mis-segregations. Overall, our findings show, for the first time, the involvement of chromosome instability in maintaining tumor heterogeneity, which underlies the enhanced growth, persistence and treatment resistance of cancers. © 2013 Hu et al.

Neutron and X-ray diffraction have been used to study the magnetic and structural properties of single crystal Nd2CuO4. Long range magnetic order of the Cu moments develops at TN=245 K, with a noncollinear antiferromagnetic arrangement of spins. Additional abrupt transitions are observed at 75 K and 30 K, in which a spin reorientation takes place. Bragg peaks associated with the crystal structure are found at the same positions as the magnetic Bragg peaks, and indicate that a distortion of the basic tetragonal structure has occurred above 300 K. © 1989.

The term “clear and distinct” is used by both Descartes and Husserl when they talk about the truth of an idea and the evidence of judgment. Although the words “clear” and “distinct” are juxtaposed with the conjunction “and,” this does not mean that their status is equal. If the concept of “evidence” can be used to characterize the hierarchical relationship between them, then we can say that, for Descartes, distinct evidence is higher than clear evidence. For Husserl, on the contrary, clear evidence is higher than distinct evidence. Their opposing views concerning the hierarchy between clarity and distinctness is symptomatic of the differences between their two understandings of the epistemological relationship between intellect and sensibility, as well as of their respective ontological reach.