Nuclear recoil measurements in Superheated Superconducting Granule detectors

The response of Superheated Superconducting Granule (SSG) devices to nuclear recoils has been explored by irradiating SSG detectors with a 70Me$\!$V neutron beam. In the past we have tested Al SSG and more recently, measurements have been performed with Sn and Zn detectors. The aim of the experiments was to test the sensitivity of SSG detectors to recoil energies down to a few ke$\!$V. In this paper, the preliminary results of the neutron irradiation of a SSG detector made of Sn granules 15-20$\mu$m in diameter will be discussed. For the first time, recoil energy thresholds of $\sim$1ke$\!$V have been measured.Comment: 7pages in Latex format, Preprint Bu-He 93/6 (University of Berne, Switzerland), four figures available upon request via [email protected] or [email protected]

Gene transfer into stimulated and unstimulated T lymphocytes by HIV-1-derived lentiviral vectors

Genetic modification of T lymphocytes holds great potential for treatments of cancer, T cell disorders and AIDS. While in the past recombinant murine retroviruses were the vectors of choice for gene delivery to T cells, vectors based on lentiviruses can provide additional benefits. Here, we show that VSV-G pseudotyped HIV 1 vector particles delivering the enhanced green fluorescent protein (EGFP) efficiently transduce human T lymphocytes. Transduction efficiency was optimal when infection included centrifugation of cells with concentrated vector supernatant in the presence of Polybrene. In contrast to previous reports describing murine retrovirus-mediated gene transfer to T lymphocytes, fibronectin did not improve the transduction efficiency of the VSVG-pseudotyped HIV-1 particles. Similar gene transfer efficiencies were observed following stimulation of cells with PHA/IL-2 or anti-CD3i/CD28i antibodies, although greater transgene expression was observed in the latter case. Interestingly, production of vectors in the absence of the accessory proteins Vif, Vpr, Vpu and Nef was accompanied by a 50% decrease in transduction efficiency in activated T cells. Transduction of T cells that were not stimulated before infection was achieved. No transduction of non-prestimulated cells was observed with a GAL V-pseudotyped murine retroviral vector. The requirement for accessory proteins in non-prestimulated cells was more pronounced. Our results have implications for lentiviral vector targeting of other cells of the hematopoietic system including stem cells