DETECTION OF DNA-PSORALEN PHOTOADDUCTS in situ

Abstract— An immunological method, with the use of specific immune serum, has been developed for detection of 8-methoxypsoralen (8-MOP) photoadducts to DNA, formed in situ in cell nuclei, after combined treatment with 8MOP and UV-A irradiation (Zarçbska et al. , 1978). Lymphocytes fixed on slides or in suspension, and cryostat sections of different mammalian tissues, served as antigenic substrate, after treatment with 8-MOP and UV-A in vitro. Specific fluorescence in these substrates was detected in the nuclei after treatment with 30 ˜ 140 kJ/m² UV-A in the presence of 0.1-0.3 μg/cm² 8-MOP. PHA-stimulated-lymphocytes appeared to be the most sensitive substrate.
However, hairless mice treated with high doses of UV-A in vivo , 70 ˜ 360 kJ/m² did not reveal a specific fluorescence of epidermal nuclei, unless a high local concentration of 8-MOP was attained.
The apparent discrepancy in the level of photoadduct detection between the in vitro and in vivo treated specimens was explained by the low number of DNA-8-MOP-photoadducts formed in vivo under these experimental conditions. The relevance of these findings to the role of DNA-8-MOP-photoadducts formed during PUVA photochemotherapy is discussed.     

Synthesis of Unsymmetrically Substituted Hexahydroimidazo [4,5-d] Imidazole-2,5-diones and Elucidation of Reaction Pathways

We have reported the synthesis and structural elucidation of a series of hexahydroimidazo [4,5-d] imidazole-2,5-diones and hydantoins from glyoxal and substituted ureas.^1,2 The general equation of this condensation reaction and a few representative compounds: those reported, current and hypothetical, are depicted in Scheme 1.     

Catalytic Enantioselective CH Functionalization of Alcohols by Redox‐Triggered Carbonyl Addition: Borrowing Hydrogen,Returning Carbon

The use of alcohols and unsaturated reactants for the redox‐triggered generation of nucleophile–electrophile pairs represents a broad, new approach to carbonyl addition chemistry. Discrete redox manipulations that are often required for the generation of carbonyl electrophiles and premetalated carbon‐centered nucleophiles are thus avoided. Based on this concept, a broad, new family of enantioselective C? C coupling reactions that are catalyzed by iridium or ruthenium complexes have been developed, which are summarized in this Minireview.     

The role of crystallographic angle in characterizing and modeling apatite fission-track length data

Recent experimental work on apatite fission-track length measurement has documented a number of factors that can exert a considerable influence on determinations of mean length. The principal source of length variation is anisotropy of annealing and etching behavior with respect to crystallographic angle. Procedural and environmental factors that influence which angular populations are preferentially sampled during measurement lead to variations in mean length that exceed standard statistical predictions. This paper evaluates the possibility of using c-axis projection to remove angular effects, and thus make length data more reproducible and informative.     

ON QUOTIENTS OF BRAID GROUPS

ABSTRACT.

Let G be the group ?[t, t ^?1] x ?. By studying the action of the braid group B_n on the set Gⁿ , we obtain representations of B_n into a wreath product of the symmetric group and the general linear group over ?[t, t ^?1]. This in particular recovers the Burau representation of the braid group. Furthermore, some quotients of the braid group are obtained by using the representations found.     

[2 + 2]-Cycloreversions

Four-membered rings can be cleaved thermally, Photochemically, or catalytically into two π bonded fragments. Theoretical calculations, kinetic studies, and investigations of stereo- and regioselectivity have been undertaken to clarify the question of whether the reaction involves one or two steps and to permit predictions on its course. [2 + 2]-Cycloreversions have been used to clarify the structure of four-membered rings, to prepare highly reactive π electron-systems and–in combination with a [2 + 2]-cycloaddition–to protect double bonds. The combination of a cycloaddition and-reversion can be used to convert a carbonyl group into an olefin. Starting with compounds containing annelated four-membered rings, compounds with two functional groups or large ring systems can be prepared. [2 + 2]-Cycloreversions have also been discussed in connection with storage of solar energy.