High level of 3^3He polarization of 81\% Maintained in an on-beam 3^3He spin filter using SEOP

Maintaining high levels of 3He polarization over long periods of time is important to many areas of fundamental and particle beam physics. Long measurement times are often required in such experiments and the data quality is a function of the 3He polarization. This is the case for neutron scattering where the 3He can be used to analyze the spin of a scattered neutron beam and relatively small fluxes of polarized neutrons leads to experiment times longer than several days. Consequently the J\"ulich Centre for Neutron Science (JCNS) is developing spin-exchange optical pumping (SEOP) systems capable of polarizing the 3He gas in place on a typical neutron instrument. Using a polarizer device we constructed a high level of 3He polarization of 81 % \pm2% was maintained with good time stability. Such levels of polarization maintained over time will be able to reduce the measurement times for such experiments and eliminate time dependent data corrections.Comment: 4 pages 2 figure

Spin Relaxation Resonances Due to the Spin-Axis Interaction in Dense Rubidium and Cesium Vapor

Resonances in the magnetic decoupling curves for the spin relaxation of dense alkali-metal vapors prove that much of the relaxation is due to the spin-axis interaction in triplet dimers. Initial estimates of the spin-axis coupling coefficients for the dimers are 290 MHz for Rb; 2500 MHz for Cs.Comment: submitted to Physical Review Letters, text + 3 figure

Oxygen Levels Do Not Determine Radiation Survival of Breast Cancer Stem Cells

For more than a century oxygen has been known to be one of the most powerful radiosensitizers. However, despite decades of preclinical and clinical research aimed at overcoming tumor hypoxia, little clinical progress has been made so far. Ionizing radiation damages DNA through generation of free radicals. In the presence of oxygen these lesions are chemically modified, and thus harder to repair while hypoxia protects cells from radiation (Oxygen enhancement ratio (OER)). Breast cancer stem cells (BSCSs) are protected from radiation by high levels of free radical scavengers even in the presence of oxygen. This led us to hypothesize that BCSCs exhibit an OER of 1. Using four established breast cancer cell lines (MCF-7, T47D, MDA-MB-231, SUM159PT) and primary breast cancer samples, we determined the number of BCSCs using cancer stem cell markers (ALDH1, low proteasome activity), compared radiation clonogenic survival and mammosphere formation under normoxic and hypoxic conditions, and correlated these results to the expression levels of key members of the free radical scavenging systems. The number of BCSCs increased with increased aggressiveness of the cancer. This correlated with increased radioresistance (SF8Gy), and decreasing OERs. When cultured as mammospheres, breast cancer cell lines and primary samples were highly radioresistant and not further protected by hypoxia (OER∼1)

Strange bedfellows: bridging the worlds of academia, public health and the sex industry to improve sexual health outcomes

The public health response to sexually transmitted infections, particularly HIV, has been and continues to be overwhelmingly focused on risk, disease and negative outcomes of sex, while avoiding discussion of positive motivations for sex (e.g. pleasure, desire, love). Recent advocacy efforts have challenged this approach and organisations have promoted the eroticisation of safer sex, especially in the context of HIV prevention

P1-04-06: Ionizing Radiation Reprograms Non-Tumorigenic Cancer Cells into Cancer Stem Cells.

Abstract Breast cancers are thought to be organized hierarchically with a small number of breast cancer stem cells (BCSCs) able to re-grow a tumor while their progeny lack this feature. BCSCs in breast cancer have been found to be relatively resistant to radiation and several groups reported enrichment for BCSCs when breast cancers are subjected to classical anticancer treatment. Differentiation of BCSCs is thought to be unidirectional but an alternative model assumes that stemness can be obtained by clonal evolution. In this study, we quantified the number of BCSCs surviving after radiation treatment. We compared the number of surviving BCSCs to the expected number and found an increase in BCSCs after irradiation that could not be explained by current models. We propose that radiation induces a BCSC phenotype in previously non-BCSCs and show that this transition is Notch-dependent and coincided with up-regulation of the transcription factors Oct4, Sox-2, Nanog, and Klf4. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-04-06.</jats:p