Gong, Xun

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly desmoplastic cancer with limited treatment options. There is an urgent need for tools that monitor therapeutic responses in real time. Drugs such as gemcitabine and irinotecan elicit their therapeutic effect in cancer cells by producing hydrogen peroxide (H2O2). In this study, specific DNA-wrapped single-walled carbon nanotubes (SWCNT), which precisely monitor H2O2, were used to determine the therapeutic response of PDAC cells in vitro and tumors in vivo. Drug therapeutic efficacy was evaluated in vitro by monitoring H2O2 differences in situ using reversible alteration of Raman G-bands from the nanotubes. Implantation of the DNA–SWCNT probe inside the PDAC tumor resulted in approximately 50% reduction of Raman G-band intensity when treated with gemcitabine versus the pretreated tumor; the Raman G-band intensity reversed to its pretreatment level upon treatment withdrawal. In summary, using highly specific and sensitive DNA-SWCNT nanosensors, which can determine dynamic alteration of hydrogen peroxide in tumor, can evaluate the effectiveness of chemotherapeutics. Significance: A novel biosensor is used to detect intratumoral hydrogen peroxide, allowing real-time monitoring of responses to chemotherapeutic drugs.

Unrecognized pregnancy in patients presenting for elective surgery is of particular concern due to the potential for significant complications. Accurate and inexpensive urine pregnancy tests are widely available in the developed world. As a result, universal preoperative pregnancy screening is commonly implemented. However, the utility of such routine testing is controversial. We retrospectively studied 8245 immediate presurgery pregnancy tests at Mayo Clinic Hospital, Phoenix, AZ, and found 11 positive tests of which 6 were false positives. We constructed a census-based approximation for unrecognized pregnancies, which shows significantly low pretest probability in this patient population. Taken together, the utility of immediate universal presurgical pregnancy testing is questionable.

Vasculogenesis and angiogenesis are controlled by vascular permeability factor/vascular endothelial growth factor A (VEGF). Dysregulation of these physiological processes contributes to the pathologies of heart disease, cancer and stroke. Rho GTPase proteins play an integral role in VEGF-mediated formation and maintenance of blood vessels. The regulatory functions of RhoA and RhoB in vasculogenesis and angiogenesis are well defined, whereas the purpose of RhoC remains poorly understood. Here, we describe how RhoC promotes vascular homeostasis by modulating endothelial cell migration, proliferation, and permeability. RhoC stimulates proliferation of human umbilical vein endothelial cells (HUVEC) by stabilizing nuclear β-catenin, which promotes transcription of cyclin D1 and subsequently drives cell cycle progression. RhoC negatively regulates endothelial cell migration through MAPK and downstream MLC-2 signaling and decreases vascular permeability through downregulation of the phospholipase Cγ (PLCγ)/Ca2+/eNOS cascade in HUVEC. Using a VEGF-inducible zebrafish (Danio rerio) model, we observed significantly less vascular permeability in RhoC morpholino (MO)-injected zebrafish than control MO-injected zebrafish. Taken together, our findings suggest RhoC is a key regulator of vascular homeostasis in endothelial cells.

Abstract Colloidal dispersion of single-walled carbon nanotubes (SWCNTs) is often the first processing step to many of their unique applications. However, dispersed SWCNTs often exist in kinetically trapped states where aggregation can be of concern. Recent work revealed prominent DNA–SWCNT aggregation following intravascular injection. In this study, we performed detailed analysis of DNA–SWCNT aggregate formation, structure, and composition in the context of endothelial cell condition media. Interestingly, we found that aggregates formed within condition media from cells that have undergone a stress response differ in size and organization from that of the control. We also found that temperature increases also promote DNA–SWCNT associations. A mathematical model was developed to describe the kinetics of SWCNT extraction from solution. Through orthogonal optical analysis and imaging modalities, we verified that proteins form the bulk of the aggregate structure and dictate aggregate assembly at multiple levels of organization. Finally, physiochemical analysis indicated preferential extraction of low-abundance hydrophobic and charged proteins. The formed aggregates also remain relatively stable in solution, making them potential macroscopic indicators of solution content.

AbstractVEGF induces vascular permeability (VP) in ischemic diseases and cancer, leading to many pathophysiological consequences. The molecular mechanisms by which VEGF acts to induce hyperpermeability are poorly understood and in vivo models that easily facilitate real-time, genetic studies of VP do not exist. In the present study, we report a heat-inducible VEGF transgenic zebrafish (Danio rerio) model through which VP can be monitored in real time. Using this approach with morpholino-mediated gene knock-down and knockout mice, we describe a novel role of phospholipase Cβ3 as a negative regulator of VEGF-mediated VP by regulating intracellular Ca2+ release. Our results suggest an important effect of PLCβ3 on VP and provide a new model with which to identify genetic regulators of VP crucial to several disease processes.