Metal-induced cell transformation

The assay system described in the present study should be useful in screening potential metal carcinogens for their ability to induce transformation. However, further work is required to demonstrate and validate that each of the various metals induce neoplastic transformation in tissue culture. A statistically significant number of transformed colonies induced by exposure of cells to each of the metal compounds must be cloned and derived into cell lines. The tumorigenic potency of these various cell lines must be tested in nude mice. 

A useful in vitro transformation assay which may be particularly applicable for metals, is the the enhancement of hamster embryo cell transformation by simian adenovirus. Casto, et al (46) and DiPaolo et al ( ) reported that all metal salts (of a series of 38 tested) with known carcinogenic activity, increased the frequency of simian adenovirus SA-7 induced transformations. 

Recent work in our laboratory has shown that Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRRAS) can be used routinely to measure vibrational spectra of a monolayer on a low area metal surface. To achieve sensitivity and resolution, a pseudo-double beam, polarization modulation technique was integrated into the FT-IR experiment. We have shown applicability of FT-IRRAS to spectral measurements of surface adsorbates in the presence of a surrounding infrared absorbing gas or liquid as well as measurements in the UHV. We now show progress toward situ measurement of thermal and hydration induced conformational changes of adsorbate structure. The design of the cell and some preliminary measurements will be discussed. 

Various in situ methods require post-treatments to induce crystallization or phase transformation. In some cases, however, the required temperatures for these treatments may be close to or even higher than those for the thermal oxidation of the nanocarbons themselves. Furthermore, it has been shown that the oxidation temperature of CNTs can be drastically reduced to as low as 330 °C, when coated with reducible metal oxides such as Bi203 [180], This process is thought to occur via a Mars van Krev-elen mechanism and may severely reduce the potential operating temperatures for various applications such as fuel cells. 

Transformation of Syrian Hamster Cells by Metals. When cultures of cells were exposed to two nickel compounds with different carcinogenic potencies, there were differences in the incidence of transformed colonies that formed (Table II). Treatment with amorphous NiS resulted in a low incidence of transformation while treatment with crystalline NiaS2 induced the appearance of numerous transformed colonies (Table II). In this series of experiments, control cultures had no transformed colonies however, in some experiments there was an occasional incidence of spontaneous transformation. The induction of transformation by... 

Carcinogenic metal compoimds such as crystalline Ni3S2 induced a dose-dependent statistically significant incidence of transformation in secondary cultures of Syrian hamster cells. A chemically related compound, amorphous NiS, which is not carcinogenic, resulted in no statistically significant incidences of transformed colonies. Untreated control cultures also had no statistically significant incidence of transformation. We have... 

Based on the above-discussed experimental results, it can be concluded that alloying additives influence the rate of the reaction of lead oxidation at the interface grid metal I corrosion layer. Probably, they induce changes in the structure of the interface as well and thus create conditions for the reaction of lead oxidation to proceed faster or slower. Since, this is a solid-phase reaction, the changes in volume of the newly formed phase will also play their role. Considering the unit cell structures presented in Fig. 2.43 and the presumed incorporation of oxygen in the crystal lattice of lead and formation of tet-PbO, it can be expected that alloying additives wiU affect this elementary process of transformation... 

Abstract. We have reviewed work conducted in our laboratory and other laboratories investigating the carcinogenic and mutagenic effects of metals and their compounds upon in vitro systems. Preliminary data is also presented which shows the following 1) Pretreatment of Syrian hamster embryo cells with benzopyrene, an inducer of aryl hydrocarbon hydroxylase, potentiates the morphological transformation of Syrian hamster embryo cells induced by... 

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