A High-Content Small Molecule Screen Identifies Sensitivity of Glioblastoma Stem Cells to Inhibition of Polo-Like Kinase 1

Glioblastoma multiforme (GBM) is the most common primary brain cancer in adults and there are few effective treatments. GBMs contain cells with molecular and cellular characteristics of neural stem cells that drive tumour growth. Here we compare responses of human glioblastoma-derived neural stem (GNS) cells and genetically normal neural stem (NS) cells to a panel of 160 small molecule kinase inhibitors. We used live-cell imaging and high content image analysis tools and identified JNJ-10198409 (J101) as an agent that induces mitotic arrest at prometaphase in GNS cells but not NS cells. Antibody microarrays and kinase profiling suggested that J101 responses are triggered by suppression of the active phosphorylated form of polo-like kinase 1 (Plk1) (phospho T210), with resultant spindle defects and arrest at prometaphase. We found that potent and specific Plk1 inhibitors already in clinical development (BI 2536, BI 6727 and GSK 461364) phenocopied J101 and were selective against GNS cells. Using a porcine brain endothelial cell blood-brain barrier model we also observed that these compounds exhibited greater blood-brain barrier permeability in vitro than J101. Our analysis of mouse mutant NS cells (INK4a/ARF^−/−, or p53^−/−), as well as the acute genetic deletion of p53 from a conditional p53 floxed NS cell line, suggests that the sensitivity of GNS cells to BI 2536 or J101 may be explained by the lack of a p53-mediated compensatory pathway. Together these data indicate that GBM stem cells are acutely susceptible to proliferative disruption by Plk1 inhibitors and that such agents may have immediate therapeutic value.     

Diversity and distribution of reptiles in Romania

The reptile fauna of Romania comprises 23 species, out of which 12 species reach here the limit of their geographic range. We compiled and updated a national database of the reptile species occurrences from a variety of sources including our own field surveys, personal communication from specialists, museum collections and the scientific literature. The occurrence records were georeferenced and stored in a geodatabase for additional analysis of their spatial patterns. The spatial analysis revealed a biased sampling effort concentrated in various protected areas, and deficient in the vast agricultural areas of the southern part of Romania. The patterns of species richness showed a higher number of species in the warmer and drier regions, and a relatively low number of species in the rest of the country. Our database provides a starting point for further analyses, and represents a reliable tool for drafting conservation plans.     

Multifunctional liposomes for nasal delivery of the anti-Alzheimer drug tacrine hydrochloride

The purpose of this study was the development of multifunctional liposomes for nasal administration of tacrine hydrochloride. Liposomes were prepared using traditional excipients (cholesterol and phosphatidylcholine), partly enriched with α-tocopherol and/or Omega3 fatty acids. This approach was chosen in order to obtain at the same time two positive results: an enhanced drug permeation through nasal mucosa and a concomitant neuroprotective effect. Several liposome formulations were prepared using the Reverse Phase Evaporation technique followed by membrane filter extrusion. In particular, liposome capacity to enhance drug permeation was evaluated by means of membrane permeation and cellular uptake studies. Furthermore, liposome effect on neuronal viability and intracellular ROS production was evaluated as well as their cytoprotective effect against oxidative stress. All liposome formulations showed a mean diameter in the range of 175?nm to 219?nm with polydispersity index lower than 0.22, a lightly negative zeta potential and excellent encapsulation efficiency. Moreover, along with good mucoadhesive properties, multifunctional liposomes showed a markedly increase in tacrine permeability, which can be related to liposome fusion with cellular membrane, a hypothesis, which was also supported by cellular uptake studies. Finally, the addition of α-tocopherol without Omega3 fatty acids, was found to increase the neuroprotective activity and antioxidant properties of liposomes.     

Minimally-invasive Technique for Injection into Rat Optic Nerve

The rat optic nerve is a useful model for stem cell regeneration research. Direct injection into the rat optic nerve allows delivery into the central nervous system in a minimally-invasive surgery without bone removal. This technique describes an approach to visualization and direct injection of the optic nerve following minor fascial dissection from the orbital ridge, using a conjunctival traction suture to gently pull the eye down and out. Representative examples of an injected optic nerve show successful injection of dyed beads.     

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.