Lateral Diffusion Length Changes in HgCdTe Detectors in a Proton Environment

This paper presents a study of the performance degradation in a proton environment of very long wavelength infrared (VLWIR) HgCdTe detectors. The energy dependence of the Non-Ionizing Energy Loss (NIEL) in HgCdTe provides a framework for estimating the responsivity degradation in VLWIR HgCdTe due to on orbit exposure from protons. Banded detector arrays that have different detector designs were irradiated at proton energies of 7, 12, and 63 MeV. These banded detector arrays allo~vedin sight into how the fundamental detector parameters degraded in a proton environment at the three different proton energies. Measured data demonstrated that the detector responsivity degradation at 7 MeV is 5 times larger than the degradation at 63 MeV. The comparison of the responsivity degradation at the different proton energies suggests that the atomic Columbic interaction of the protons with the HgCdTe detector is likely the primary mechanism responsible for the degradation in responsivity at proton energies below 30 MeV

The Protein Maker: an automated system for high-throughput parallel purification

The Protein Maker instrument addresses a critical bottleneck in structural genomics by allowing automated purification and buffer testing of multiple protein targets in parallel with a single instrument. Here, the use of this instrument to (i) purify multiple influenza-virus proteins in parallel for crystallization trials and (ii) identify optimal lysis-buffer conditions prior to large-scale protein purification is described

Tumor-specific chromosome mis-segregation controls cancer plasticity by maintaining tumor heterogeneity.

Aneuploidy with chromosome instability is a cancer hallmark. We studied chromosome 7 (Chr7) copy number variation (CNV) 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 mis-segregation, 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

Tumor-Specific Chromosome Mis-Segregation Controls Cancer Plasticity by Maintaining Tumor Heterogeneity

<div><p>Aneuploidy with chromosome instability is a cancer hallmark. We studied chromosome 7 (Chr7) copy number variation (CNV) 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 mis-segregation, which benefited overall tumor growth <i>in vitro</i> and <i>in vivo</i>. 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.</p></div

Distinct “go” and “grow” features of two cell subpopulations in U251 with optimal equilibrium benefiting overall tumor growth.

<p><b>A</b>, H&E images (2X) and FISH images (100X) of i.c. xenografts derived from NS1. <i>Arrowhead</i>, <i>double</i> and <i>single arrow</i> point to cells with 1, 2, and 3 copies of Chr7, respectively. <b>B</b>, comparison of cell population equilibrium in NS1 (<i>in vitro</i> culture) and the derived i.c. tumors. <b>C</b>, fluorescence images of i.c. xenografts derived from co-implantation of RFP-labeled STIC-enriched U251-NS and GFP-labeled U251 in a 9∶1 ratio. <b>D–E</b>, immunofluorescence images of i.c. xenografts from co-implantation of the two lines in a 1∶99 ratio, with purple color marking BMI1 and MELK expression by RFP cells at the tumor boundary and their expression of CD133 and SPARC in vascular mimicry within the bulk tumor mass. <b>F</b>, confocal immunofluorescence images of i.c. xenografts derived from 100% RFP cells, with yellow color marking co-localization of RFP with CD31 or GFAP. <b>G</b>, Kaplan-Meier survival curves of mice after implanting a mixture of U251 parental and STIC-enriched NS subculture. Adjusted Hazard ratios (HRs) from the stratified analysis and p-value are from Cox regression analyses examining the effect of STIC percentage on survival.</p

Proportion of cells with Chr7 number variation in high- and low-grade gliomas and glioma primary cultures.

<p><b>A</b>, ternary plot of population proportions with 1 copy (deletion), 2 copies (normal), and 3 or more (amplification) copies of Chr7, based on CEP7 signals in Ffuorescent <i>in situ</i> hybridization (FISH) of 14 glioblastoma multiformes (GBMs, <i>Red triangle</i>) and 12 oligodendroglial tumor (OGs, <i>black square</i>), <i>P</i> = 0.0012 from MANOVA analysis. <b>B</b>, comparison of tumor heterogeneity with regard to chromosome 7 (Chr7) aneuploidy in the original tumor (T) and corresponding 3–4 week-old primary cultures under serum adherent (SA) or neural sphere (NS) culture conditions. <b>C–D</b>, patterns of cells with Chr7-CNV in sequential and high-EGFR amplified GBMs. Representative FISH pictures of cells carrying 1–4 copies of Chr7 with focal EGFR amplification.</p

Re-examination of U251-NS1 cell s.c. tumorigenicity after overexpression of VEGFA.

<p>U251-NS1 infected with retrovirual vectors of VEGF-165 and LacZ described previously <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0080898#pone.0080898-Hu1" target="_blank">[35]</a> were s.c. implanted in nude mice as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0080898#s2" target="_blank">Materials and Methods</a>.</p

Mathematical modeling of experimental data with changes in population equilibrium from homogeneity to heterogeneity.

<p><b>A</b>, schematic illustration of the working mechanism with Chr7-MS resulting in heterogeneous subpopulations and cellular phenotype inter-conversion, with STIC inhibiting growth of TMC and/or TMC stimulating growth of STIC. The Chr7 composition was shown for representative subpopulation cells in U251, based on metaphase FISH.A higher growth rate for TMC (<i>r</i>₃) was shown compared to that for STIC (<i>r</i>₂). Cells marked by black circles were seen in metaphase FISH analysis, suggesting their ability to grow <i>in vitro</i>. Cells marked by gray boxes were not seen in metaphase FISH analysis, suggesting they are unable, or have very low ability to grow <i>in vitro</i>. <b>B</b>, changes in population equilibrium from homogeneity to heterogeneity in NS1 after serial, three-day passages in SA-culture conditions, using the same cell plating density (5×10⁵/100 mm dish), with cell types determined by FISH (experimental) and then modeled using different parameters as detailed in Methods. <b>C</b>. changes in cell growth speed as measured or predicted by various mathematical models. <b>D</b>, s.c. tumorigenicity assay showing the TMC features of 3Chr7:2n,1d cells converted from STIC by increasing percentage tumor onset (a tumor size of ∼50 mm³). The plot with percent uses percents computed via the Kaplan-Meier method. Log-rank test for trend with 3Chr7:2n,1d cells shows two-sided <i>P</i><0.0001.</p

Distinct karyotypes of three subpopulation cells in U251.

<p><b>A</b>, representative metaphase FISH pictures of PTEN/CEP10 and EGFR/CEP7 dual probes showing all cells carrying one copy of Chr10, an unknown chromosome with a PTEN translocation, and three cell types differing in their composition of normal and derivative Chr7 (dChr7). <i>Arrow</i> points to dChr7; <i>arrowhead</i> to normal Chr7. <b>B</b>, percentage of majority cells in the parental culture, derived or converted SA or NS subcultures, and the parental culture after lentiviral transductions by pTRIPZ-Vec (P-Vec), pTRIPZ-EFEMP1 with (P-E1) or after withdrawal (P-E1wd) of doxycyclin. <b>C–D</b>, comparison of DNA copy number variation in chromosomes 7, 8, 17, and 22 for U251 parental derived or converted NS subcultures of NS1 or SA1-NS, respectively. The Y axis is the log ratio of intensity (the ratio of test sample and normal blood) from comparative genome hybridization. Amplifications or deletions are shown by blue lines above or below the red or green areas, respectively, based on Z-score, and those with marked changes are highlighted in purple.</p