Targeting oncogenic pathways holds promise for brain tumor treatment, but inhibition of Sonic Hedgehog (SHH) signaling has failed in SHH-driven medulloblastoma. Cellular diversity within tumors and reduced lineage commitment can undermine targeted therapy by increasing the probability of treatment-resistant populations. Using single-cell RNA-seq and lineage tracing, we analyzed cellular diversity in medulloblastomas in transgenic, medulloblastoma-prone mice, and responses to the SHH-pathway inhibitor vismodegib. In untreated tumors, we find expected stromal cells and tumor-derived cells showing either a spectrum of neural progenitor-differentiation states or glial and stem cell markers. Vismodegib reduces the proliferative population and increases differentiation. However, specific cell types in vismodegib-treated tumors remain proliferative, showing either persistent SHH-pathway activation or stem cell characteristics. Our data show that even in tumors with a single pathway-activating mutation, diverse mechanisms drive tumor growth. This diversity confers early resistance to targeted inhibitor therapy, demonstrating the need to target multiple pathways simultaneously.

No abstract

No abstract

A quantitative mass spectrometry imaging (QMSI) technique using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is demonstrated for the antiretroviral (ARV) drug emtricitabine in incubated human cervical tissue. Method development of the QMSI technique leads to a gain in sensitivity and removal of interferences for several ARV drugs. Analyte response was significantly improved by a detailed evaluation of several cationization agents. Increased sensitivity and removal of an isobaric interference was demonstrated with sodium chloride in the electrospray solvent. Voxel-to-voxel variability was improved for the MSI experiments by normalizing analyte abundance to a uniformly applied compound with similar characteristics to the drug of interest. Finally, emtricitabine was quantified in tissue with a calibration curve generated from the stable isotope-labeled analog of emtricitabine followed by cross-validation using liquid chromatography tandem mass spectrometry (LC-MS/MS). The quantitative IR-MALDESI analysis proved to be reproducible with an emtricitabine concentration of 17.2±1.8 μg/gtissue. This amount corresponds to the detection of 7 fmol/voxel in the IR-MALDESI QMSI experiment. Adjacent tissue slices were analyzed using LC-MS/MS which resulted in an emtricitabine concentration of 28.4±2.8 μg/gtissue.

Chemical reaction between DTT and oxygen with PM as a catalyst…………. 2. UNC Aerosol Smog Chamber…………………………………………………. 3. An example of UV-VIS absorption spectrum. Spectra were recorded using a Hitachi U-3300 spectrophotometer…………………………………………... 4. Diesel exhaust particles (DEP) experiments conducted in the UNC outdoor chamber facility. (a) "North : Diesel only" means DEP was aging and reacting without UNC mix under natural sunlight. (b) "South: Diesel and UNC mix" means UNC mix was injected into the system and DEP was aging and reacting with UNC mix under natural sunlight. The experiment was conducted on Apr 28, 2010. The initial UNC mix in the system was 8 ppmC……………….. 5. Diesel exhaust particles (DEP) experiments conducted in the UNC outdoor chamber facility. (a) "North : Diesel only" means DEP was aging and reacting without UNC mix under natural sunlight. (b) "South : Diesel and UNC mix" means UNC mix was injected into the system and DEP was aging and reacting with UNC mix under natural sunlight. The experiment was conducted on Apr 16, 2010. The initial UNC mix in the system was 1 ppmC…………...…... 6. The comparison of oxidant generation and toxicity index (NIOG) between without the UNC mix in the system (North) and with the UNC mix in the system (South) The experiment was performed on Apr 28, 2010. The error bars show a 95% confidence interval……………………………………………………………. 7. The comparison of oxidant generation and toxicity index (NIOG) between without the UNC mix in the system (North) and with the UNC mix in the system (South) The experiment was performed on Apr 16, 2010. The error bars show a 95% confidence interval……………………………………………………………. 8. The comparison of DTT activity (nmole DTT per minute per microgram PM) between without the UNC mix in the system (North) and with the UNC mix in the system (South). The experiment was performed on Apr 28, 2010. The error bars show a 95% confidence interval……………………………… viii 9. The correlation between samples in each period and the selected PAH concentration……………………………………………………. 10. The linear regression analysis of Phenanthrene and DTT activity…………….. 11. The comparison of oxidant generation and toxicity index (NIOG) between nighttime and daytime systems: nighttime without and with ozone by Li et al. (2009); daytime without and with UNCmix from this paper. The error bars show a 95% confidence interval…………........ 12. The Box and Whisker Plot of grouped SOA redox activity: "No additional VOCs" refers to the system of NOx and UNC mix only. Additional α-pinene means the system of NOx+ UNC mix+α-pinene. "Xylene without toluene" refers to the system of xylene and UNC mix without toluene.…………………………….... 33