MUTAGENIC EFFECTS PHOTOINDUCED IN MAMMALIAN CELLS IN VITRO BY TWO MONOFUNCTIONAL PYRIDOPSORALENS

Abstract— The photobiological activity of the two monofunctional pyridopsoralens pyrido (3,4-c) psoralen (PyPs) and 7-methyl pyrido (3,4-c) psoralen (MePyPs) was studied in mammalian cells in vitro taking 8-methoxypsoralen (8-MOP) as a reference compound.
In the presence of 365-nm irradiation (UVA) MePyPs was found to be more effective than 8-MOP in terms of DNA photobinding capacity and inhibition of cell cloning ability in Chinese hamsterV–79 cells. As a function of UVA dose and of the number of total photoadducts induced MePyPs produced a higher frequency of 6-thioguanine resistant mutants than 8-MOP. PyPs showed an intermediate response for cell killing and mutation induction. At equal cytotoxic levels both monofunctional pyridopsoralens exhibited the same mutagenic activity as the Afunctional furocoumarin 8-MOP.
The antiproliferative effect being taken as indicative for an efficient photochemotherapeutic activity against psoriasis, the inhibition of cloning capacity induced by MePyPs plus UVA was studied in parallel on human skin fibroblasts. Such cells were more sensitive to 8-MOP photoadditions thanV–79 cells and even more so to MePyPs photoadditions. Data obtained on the rate of DNA semi conservative synthesis on both cell lines following treatments with the two compounds are in line with these observations.     

Homologies associées aux variétés de Poisson

In this article, we obtain results on the cyclic homology of Poisson manifolds as defined by Kassel. In particular, we compute the cyclic homology of any symplectic variety. We also show that there exists a family of new operators of the type of the S operator of Connes, defined on the cyclic homology of a Poisson manifold, and describe the associated exact triangles associated to these new operators.

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Received February 23, 1998 / Published online July 20, 2000     

HIGH LEVELS OF 4,5'',8-TRIMETHYLPSORALEN PHOTOINDUCED FURAN-SIDE MONOADDUCTS CAN BLOCK CROSS-LINK REMOVAL IN NORMAL HUMAN CELLS

Abstract— The induction and removal of DNA interstrand cross-links (CL) was studied in normal human fibroblasts (1BR/3) using the highly photoreactive furocoumarin 4,5',8-trimethylpsoralen (TMP) in combination with monochromatic 365 nm and/or 405 nm radiation. We report that the presence of large amount of furan-side monoadducts (MA_f) induced by TMP plus 365 nm radiation blocks CL incision. When the amount of MA_f is reduced by their conversion into even more CL, incision of the cross-links is more efficient.     

A Combinatorial Character Formula for Some Highest Weight Modules

We give a combinatorial formula for the weight multiplicities of some infinite-dimensional highest weight (n)-modules. Our proof, which does not rely on Kazhdan–Lusztig combinatorics, uses a reduction to finite characteristics. The character formula for the corresponding modular representations, which has been computed in a 1997 preprint by the authors, is based on a dual pair which has no obvious counterpart in characteristic zero.     

On the Leibniz Homology of Poisson Algebras

We study the Leibniz homology of the Poisson algebra of polynomial functions over (²ⁿ ,) where is the standard symplectic structure. We identify it with certain highest-weight vectors of some _2n ( )-modules and obtain some explicit result in low degree.     

A character formula for a family of simple modular representations of $ GL_n $

Let K be an algebraically closed field of finite characteristic p, and let be an integer. In the paper, we give a character formula for all simple rational representations of with highest weight any multiple of any fundamental weight. Our formula is slightly more general: say that a dominant weight λ is special if there are integers such that and . Indeed, we compute the character of any simple module whose highest weight λ can be written as with all are special. By stabilization, we get a character formula for a family of irreducible rational -modules. Received: June 30, 1997.     

Correlated use of characterization techniques to optimize the Mg implantation annealing for self-aligned HBT''s

The annealing process of Mg-implanted GaAs/GaAlAs HBT's has been optimized using different analysis techniques. The Mg activation was deduced from a comparison between the atomic profile determined by SIMS and the electrical profile determined by electrochemical C-V profiling. Under the optimum annealing conditions, a record activation value of 87% was reached. Cathodoluminescence analysis has also been used to assess the quality of the implanted materials.