Ultrastructural apoptotic lesions induced in bone marrow after neptunium-237 contamination.

This study describes the ultrastructure of lesions induced by neptunium-237 (237Np), a by-product of uranium in nuclear reactors, in the bone marrow. A group of rats were given a single injection of 237Np-nitrate solution in order to observe the acute toxicity effects of this actinide. Electron microscopy was used to describe the different lesions. Observations included the swelling of the cell membrane, nuclear membrane lyses, abnormal chromatin condensation or nucleus convolution. These ultrastructural alterations of the nucleus and the cellular membrane appeared shortly after treatment. This study demonstrates the toxic effects of neptunium and its implication in the induction of apoptosis in bone marrow.

Ultrastructural lesions induced by neptunium-237: apoptosis or necrosis?

In this study, we are concerned with the 237 isotope of neptunium (237Np), which is a by-product of uranium in nuclear reactors. To study ultrastructural lesions induced by this element, a group of rats were injected with a solution of 237Np-nitrate once a day for 14 weeks. Lesions observed in liver and kidney are described using electron microscopy. Ultrastructural alterations of cellular membranes and intracellular organelles demonstrated the existence of neptunium toxicity. This toxicity was characterized by various lesions, such as cytoplasmic clarification, disappearance of mitochondrial cristae, swollen mitochondria, abnormal condensation of nuclear chromatin, and nuclear fragmentations. This study demonstrated the probable induction of apoptosis by neptunium both in liver and kidneys.

3-D confocal microscopy of etched nuclear tracks in CR-39.

Solid State Nuclear Track Detectors (SSNTD's) are used in a wide range of applications such as Geological Dating, Environmental Sciences (radon), life Sciences (Radiobiology, Dosimetry...), as well as Nuclear and Astro-Physics. In order to be observable under a microscope, the nanometric latent damaged trails due to the slowing down of charged particles into the SSNTD have to be specifically etched. In our laboratory, we are studying this chemical action and propose models that enable simulations to be performed. In the literature, the basic model uses two distinct etch-rates that are considered constant, VB; the Bulk and VT the Track etch-rate. A little bit more sophisticated and realistic, a model with a variable track etch-rate was established, taking into account the variation of energy deposition along the particle's trajectory. Up to now, the known methods used for determining the response function of CR-39 are very time consuming and strenuous. The method we present here is based on the use of the confocal microscope, which provides three-dimensional track images. The obtained set of 3-D co-ordinates can be treated mathematically, giving, in the framework of the two etch-velocity model, the response function. With this new approach, tracks are analysed one by one; response functions are obtained for each track and can be compared to fundamental characteristics of the charged Particle-Matter interactions. Moreover, the method we propose is applied semi-automatically and could easily be automated in the near future.