Reaction of isopropenylcyclopropane with arylsulfenyl chlorides and the isomerization of the adducts

Conclusions The addition of arylsulfenyl chlorides to isopropenylcyclopropane may, according to the polarity of the medium, proceed by normal addition at the double bond to give the 1,2-adducts, or by homoallyl rearrangement to give the corresponding homoprenyl chlorosulfides. Some bifunctional isoprenoid C₆-synthones have been obtained.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2314–2319, October, 1984.     

Automation of the optical alignment of a diode-laser spectrometer by means of simplex optimization

Optimization of the optical alignment of a tunable diode-laser spectrometer can be automated by using a commercially available Simplex optimization program. This alignment is achieved by displacing a collimation lens placed in front of the laser in three mutually perpendicular directions by motorized positioning equipment. The detector signal, after lock-in amplification, is taken as the optimization criterion. Best parameter settings of the program are discussed on the basis of experimental results. It is demonstrated that the program gives very reliable results in terms of reproducibility of the optimal alignment.     

[3,3]-Sigmatropic rearrangements of the acetoacetates of allyl alcohols (Carroll reaction) and allylphenyl ethers (Claisen reaction) on the surface of adsorbents

A method has been developed for effecting rearrangements of allylacetoacetates to ,-unsaturated ketones (Carroll rearrangement) and allylaryl ethers to the corresponding allylphenols (Claisen rearrangement) under conditions of adsorption on aluminum oxide and silica gel. The method provides a sharp reduction of the temperature of these reactions and improvement of their efficiency.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 835–842, April, 1991.     

Melanin content of cultured human melanocytes and UV-induced cytotoxicity

Cultured melanocytes originating from persons with different skin phototypes were utilized for measurement of endonuclease sensitive sites induced by UVB and the determination of cell survival after UVA or UVB irradiation. During culture, the melanocytes largely maintained their phenotypic characteristics according to their original skin phototype. Total melanin concentrations were 4.9 times higher in the darker skin phototype (IV-VI) melanocytes when compared to the cells from lighter skin phototypes (I-III). Also phaeomelanin contents were higher (2.5 times) in the skin phototype (IV-VI) melanocytes which implies that the cells from light skin types contain less melanin, but a relatively high proportion of phaeomelanin. After UVB irradiation a stronger induction of endonuclease sensitive sites was found for melanocytes with a lower level of total melanin and a high content of pheomelanin. By measuring the clone forming ability in different melanocyte cultures after UVB irradiation, significant better survival was found in case of the cells with the higher melanin content. Despite the large variations in melanin content, no significant difference in survival after UVA irradiation could be demonstrated in this way. Our results suggest a protective effect of melanin for UVB and indicate the importance of the measurements of melanin content and composition when different parameters of UV-induced damage are studied in melanin producing cells.