Synthesis of Polyurethane Hydrogel and Polyurethane Thermoplastic Elastomer Composite Based Separation Membranes.

A series of polyurethane hydrogel and polyurethane thermoplastic elastomer composite based separation membranes were successfully prepared via wet phase inversion method. The morphology, chemical structure, phase transition temperature and crystallinity of the polyurethane (PU) membranes were characterized by SEM, FTIR, DSC, and XRD, respectively. The SEM observation showed that the PU membranes exhibited irregular porous structure on the surface and path of the hole was flexural and asymmetrical in cross-section. The FTIR analysis demonstrated that thermalsensitive groups and pH-sensitive components (-N(CH3)-) were incorporated into the PU network. The DSC experiment and XRD experiment showed that the regular arrangement of PU network was destroyed partly due to the introduction of polyurethane thermoplastic elastomer. The equilibrium swelling ratio (ESR) and water flux (J) for PU membranes clearly decreased and increased with functional groups and sophisticated structure of PU membranes, respectively. In addition, the permeation experiments indicated that the permeation percentage (P) of the glycine was strongly affected by the external temperature and pH value.

Quantitative and morphometric evaluation of the angiogenic effects of leptin.

Angiogenesis is a dynamic process that requires an interaction of pro-and antiangiogenic factors. It is known that the cytokine leptin stimulates endothelial cell growth and angiogenesis, but further quantitative analysis is necessary to understand leptin angiogenic effects. The quail chorioallantoic membrane (CAM) assay has been used to study angiogenesis in vivo by focusing on morphometric parameters that quantify vascular complexity and density. We quantify the angiogenic activity of leptin using the CAM assay by digital morphometry and a computer-assisted image analysis to evaluate more precisely vessel length, diameter, branching, and tortuousity. CAM images are obtained from ex ovo cultures of E8-E9 quail embryos. MATLAB and custom software are used for our analysis. The effects of leptin, vascular endothelial growth factor-165 (VEGF(165)), and their corresponding neutralizing antibodies are compared. Our results show that CAM treated with leptin and VEGF(165) has a significant increase in vascular complexity and density. A corresponding decrease is observed using neutralizing antibodies. Notably, leptin induced more significant changes than VEGF in vessel length and tortuousity. Conversely, VEGF induced a greater increase in vessel branching than leptin. These results underscore the importance of using multiparametric quantitative methods to assess several aspects of angiogenesis and enable us to understand the proangiogenic effects of leptin.

Isolation of cancer stem cells from adult glioblastoma multiforme.

Glioblastoma multiforme (GBM) is the most common adult primary brain tumor and is comprised of a heterogeneous population of cells. It is unclear which cells within the tumor mass are responsible for tumor initiation and maintenance. In this study, we report that brain tumor stem cells can be identified from adult GBMs. These tumor stem cells form neurospheres, possess the capacity for self-renewal, express genes associated with neural stem cells (NSCs), generate daughter cells of different phenotypes from one mother cell, and differentiate into the phenotypically diverse populations of cells similar to those present in the initial GBM. Having a distinguishing feature from normal NSCs, these tumor stem cells can reform spheres even after the induction of differentiation. Furthermore, only these tumor stem cells were able to form tumors and generate both neurons and glial cells after in vivo implantation into nude mice. The identification of tumor stem cells within adult GBM may represent a major step forward in understanding the origin and maintenance of GBM and lead to the identification and testing of new therapeutic targets.