Telomerase activity, apoptosis and cell cycle progression in ataxia telangiectasia lymphocytes expressing TCL1

Individuals affected by ataxia telangiectasia (AT) have a marked susceptibility to cancer. Ataxia telangiectasia cells, in addition to defects in cell cycle checkpoints, show dysfunction of apoptosis and of telomeres, which are both thought to have a role in the progression of malignancy. In 1-5% of patients with AT, clonal expansion of T lymphocytes carrying t(14;14) chromosomal translocation, deregulating TCL1 gene(s), has been described. While it is known that these cells can progress with time to a frank leukaemia, the molecular pathway leading to tumorigenesis has not yet been fully investigated. In this study, we compared AT clonal cells, representing 88% of the entire T lymphocytes (AT94-1) and expressing TCL1 oncogene (ATM- TCL1 +), cell cycle progression to T lymphocytes of AT patients without TCL1 expression (ATM- TCL1-) by analysing their spontaneous apoptosis rate, spontaneous telomerase activity and telomere instability. We show that in ATM- TCL1+ lymphocytes, apoptosis rate and cell cycle progression are restored back to a rate comparable with that observed in normal lymphocytes while telomere dysfunction is maintained. © 2003 Cancer Research UK

Temperature and field dependence of the spin magnetization density in SmMn₂Ge₂

The site specific spin moments in the layered intermetallic compound SmMn2Ge2 have been measured directly as a function of field, between 0.02 and 1 T, using the spin-polarized Compton scattering technique at 13, 40, and 230 K. The field dependence of the orbital moment has been determined by comparison at each temperature with magnetometry data. A small finite Sm spin moment is observed at a low applied field of 0.02 T. These data indicate that in the high-temperature ordered phase the rare-earth sites exhibit a small net moment and exhibit paramagnetic behavior with little coupling to the Mn spin sublattice. Our low-temperature, low-field data indicate a change in magnetic order of the Sm site at approximate to35 K that is metamagnetic in nature. However, we find no evidence for a zero-field transition in the Sm sublattice as previously suggested