Arsenic exposure in the wine growing industry in ten French departments.

OBJECTIVES: This study investigated exposure to arsenic, a carcinogenic fungicide used in wine growing. METHODS: The first phase compared urinary arsenic excretion of controls and workers exposed at the end of application. The second phase measured the increase in urinary arsenic excretion during the first day of use. RESULTS: A significant increase in urinary arsenic excretion was observed in arsenic applicators during the first phase. Urinary arsenic concentrations exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) exposure index in one-third of the workers. The second phase showed a significant increase in urinary arsenic excretion by the first day of application. A closed tractor cabin provided a protective effect, but the efficacy of individual protection equipment was not demonstrated. CONCLUSION: This study showed the difficulties of achieving the effective protection of arsenic applicators and has led to the banning of the use of arsenic in French vineyards.

Experimental study of stochastic noise propagation in SPECT images reconstructed using the conjugate gradient algorithm.

Thanks to an experimental study based on simulated and physical phantoms, the propagation of the stochastic noise in slices reconstructed using the conjugate gradient algorithm has been analysed versus iterations. After a first increase corresponding to the reconstruction of the signal, the noise stabilises before increasing linearly with iterations. The level of the plateau as well as the slope of the subsequent linear increase depends on the noise in the projection data.

A comparative study of Powell's and Downhill Simplex algorithms for a fast multimodal surface matching in brain imaging.

Multimodal images registration can be very helpful for diagnostic applications. However, even if a lot of registration algorithms exist, only a few really work in clinical routines. We developed a method based on surface matching and compared two minimization algorithms: Powell's and Downhill Simplex. We studied the influence of some factors (chamfer map computation, number and order of parameters to determine, minimization criteria) on the final accuracy of the algorithm. Using this comparison, we improved some processing steps to allow a clinical use, and selected the simplex algorithm which presented the best results.

Acquisition of CD80 (B7-1) by T cells.

Activation of T cells usually requires two signals. Signal 1 is mediated via a peptide-MHC on the APC; signal 2 is mediated via a costimulatory molecule on the APC surface. We demonstrate here that naive CD4(+) T cells actually acquire the costimulatory molecule CD80 (B7-1) from syngeneic APCs after activation. This phenomenon was demonstrated showing acquisition of CD80 by T cells from CD80/CD86 (B7-2) knockout mice, and by treating T cells with cyclohexamide to further rule out endogenous expression of CD80 by T cells. Moreover, no CD80 mRNA could be detected in T cells that had acquired CD80. The amount of acquisition of CD80 by T cells was shown to be directly related to both the strength of signal 1 and the amount of CD80 on the APC. Specificity of this acquisition was also shown by the lack of acquisition by T cells from CD28 knockout mice (implicating CD28 in this process), the lack of acquisition of CD40 (another molecule on the APC surface) by T cells, and confocal microscopy studies. We demonstrate for the first time that 1) naive T cells, following acquisition of CD80 from APCs, were themselves shown to be capable of acting as APCs; and 2) memory T cells that have acquired CD80 from APCs undergo apoptosis in the presence of increased levels of signal 1. Thus we demonstrate both immunostimulatory and immunoregulatory functions as a result of CD80 acquisition by different T cell populations.

A vine-growing exposure matrix in the Hérault area of France.

In the Hérault region of France, vineyards cover an area of 128,000 hectares (60% of agricultural land) and involve more than 93% of farms. A vine-growing exposure matrix was built for assessing pesticide exposure. It is based on information obtained from a survey among 85 vine-growers who lived in Hérault and who had detailed account books. This paper explains how this matrix was built and how to use it. It takes into consideration the calendar time (1950-1988), the type of products (powder, liquid) and the chemical classes. It can estimate the likelihood of exposure and the quantity of pesticide used. Such a matrix could be useful in epidemiological surveys in order to measure vine-growers' exposure to pesticides. Formulae are given to evaluate their mean exposure to these chemicals. Limitations of the matrix are discussed; it does not take into account several factors which might change exposure: temperature, wind speed, methods of application, use of protection, etc.