Tumour biology: senescence in premalignant tumours

Oncogene-induced senescence is a cellular response that may be crucial for protection against cancer development, but its investigation has so far been restricted to cultured cells that have been manipulated to overexpress an oncogene. Here we analyse tumours initiated by an endogenous oncogene, ras, and show that senescent cells exist in premalignant tumours but not in malignant ones. Senescence is therefore a defining feature of premalignant tumours that could prove valuable in the diagnosis and prognosis of cancer.     

Determination of trace elements in peripheral lymphocytes from tumor-bearing rats.

Neutron activation analysis of peripheral lymphocytes from healthy and Walker 256 carcinosarcoma-bearing rats resulted in the quantitative determination of Co, Cu, K, Mn, Rb, Se and Zn, and a qualitative determination of Au and Sb. From corresponding plasma samples, Co, Zn, Rb, Se and Cs were analyzed. Differences in trace element concentrations could only be detected in plasma of tumor-bearing animals which showed a decreased Zn and Co content of 50% and 30%, respectively, and a rise of Rb when compared to plasma of control animals.     

Determination of trace elements in peripheral lymphocytes from tumor-bearing rats

Summary Neutron activation, analysis of peripheral lymphocytes from healthy and Walker 256 carcinosarcoma-bearing rats resulted in the quantitative determination of Co, Cu, K, Mn, Rb, Se and Zn, and a qualitative determination of Au and Sb. From corresponding plasma samples, Co, Zn, Rb, Se and Cs were analyzed. Differences in trace element concentrations could only be detected in plasma of tumor-bearing animals which showed a decreased Zn and Co content of 50% and 30%, respectively, and a rise of Rb when compared to plasma of control animals.     

Electrostatic trapping of ammonia molecules

The ability to cool and slow atoms with light for subsequent trapping allows investigations of the properties and interactions of the trapped atoms in unprecedented detail. By contrast, the complex structure of molecules prohibits this type of manipulation, but magnetic trapping of calcium hydride molecules thermalized in ultra-cold buffer gas and optical trapping of caesium dimers generated from ultra-cold caesium atoms have been reported. However, these methods depend on the target molecules being paramagnetic or able to form through the association of atoms amenable to laser cooling, respectively, thus restricting the range of species that can be studied. Here we describe the slowing of an adiabatically cooled beam of deuterated ammonia molecules by time-varying inhomogeneous electric fields and subsequent loading into an electrostatic trap. We are able to trap state-selected ammonia molecules with a density of 10(6) cm(-3) in a volume of 0.25 cm3 at temperatures below 0.35 K. We observe pronounced density oscillations caused by the rapid switching of the electric fields during loading of the trap. Our findings illustrate that polar molecules can be efficiently cooled and trapped, thus providing an opportunity to study collisions and collective quantum effects in a wide range of ultra-cold molecular systems.