Combined effect of the extracts from Croton tiglium, Euphorbia lathyris or Euphorbia tirucalli and n-butyrate on Epstein-Barr virus expression in human lymphoblastoid P3HR-1 and Raji cells.

The combined usage of n-butyrate and 12-O-tetradecanoylphorbol-13-acetate (TPA) or the oily extracts from Croton tiglium, Euphorbia lathyris or Euphorbia tirucalli exerted a marked effect on induction of Epstein-Barr virus (EBV)-associated early (EA) and viral capsid (VCA) antigens in EBV genome-carrying human lymphoblastoid cell lines. In producer P3HR-1 cells, the enhancing effect of the 2 components was additive both for EA and VCA, while in non-producer Raji cells, a synergistic increase of EA was observed. The possible implication of these findings relating to the cause of EBV-associated diseases is discussed.

A short-term in vitro assay for promoter substances using human lymphoblastoid cells latently infected with Epstein-Barr virus.

We designed a short-term in vitro assay for detecting tumor promoters, utilizing the activation of Epstein-Barr virus (EBV) expression in EBV genome-carrying human lymphoblastoid cells. This system is composed of EBV-non-producer Raji cells as the indicator, n-butyrate as the EBV-inducer, and the test substance. After addition of the latter 2 components to the culture medium, the cells are cultivated for 48 h at 37 degrees C and the ratio of EBV early antigen (EA)-expressing cells was assessed using immunofluorescence. This assay system allows for a rapid detection of the activity of the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and its related compounds and also of the Euphorbiaceae plant extracts containing such active principles. Among several microbial products tested, teleocidin, an indole-alkaloid produced by a Streptomyces species, was also detected and had an activity level comparable to that of TPA. Other promoters, such as anthralin, phenol, Tween 60 and 80 and the carcinogenic ("initiator") substances including benzopyrene, did not react with the system. The test is simple to perform, reproducible and should be applicable for mass-screening of promoter substances in the environment.

Anomalous substituent effects in the bischler-napieralski reaction of 2-aryl aromatic formamides

Treatment of some 1-naphthylformamides (or formanilides) possessing a 2,4,5-trioxygenated phenyl substituent at the 2-position with POCl(3) caused an unprecedented carbon insertion reaction into a benzene ring, producing 7-5 ring (azaazulene) systems as valence isomers of isoquinoline skeletons. Precise examination of this abnormal Bischler-Napieralski reaction (BNR) using various substrates led to the following scope and limitations: (i) the 7-5 ring systems were constructed when either 2-alkoxy-4, 5-methylenedioxyphenyl- or 4,5-dialkoxy-2-hydroxyphenyl-substituted formamides were used as a starting substrate; (ii) in the former case the formyl carbon was inserted into the C(1)-C(6) bond of the 2-phenyl group, and normal isoquinoline cyclization competed with an abnormal carbon insertion reaction; (iii) the presence of a hydroxy group at the 2'-position as in the latter cases caused exclusive carbon insertion, in which alternative C(1)-C(2) insertion products were quantitatively formed; (iv) 3, 6-dimethoxy-2-hydroxyphenyl-substituted formanilide electronically equivalent to 4,5-dialkoxy-2-hydroxy derivatives produced an indole-pyrone as an abnormal BNR product. Theoretical approaches using the PM-3 method indicated that these abnormal BNRs could be triggered by ipso attack at the 1'-position yielding spiro intermediates. Ring cleavege of the six-membered ring in the spiro intermediates to a ketene function followed by recyclization was proposed for the 2'-hydroxy-directed abnormal BNRs leading to the C(1)-C(2) insertion product or the indole-pyrone derivative.

Diffusion of particles bouncing on a one-dimensional periodically corrugated floor.

We report on a class of spatially extended mechanical systems sustaining a transport process of diffusive type. These systems consist of a point particle subject to a constant vertical acceleration and bouncing on a one-dimensional periodically corrugated floor. We show that the deterministic dynamics of these systems is chaotic with small elliptic islands for many parameter values. The motion of particles perturbed by a small noise has a horizontal diffusion that is normal. In such a case, we show that the diffusion coefficient oscillates periodically as the energy of particles increases. In the absence of noise, there still exists an effective numerical value for the diffusion coefficient and this value has an irregular dependence on energy.

Quantum-classical correspondences of the Berry-Robnik parameter through bifurcations in lemon billiard systems.

The quantum level statistics affected by bifurcations in classical dynamics is studied by using a one-parameter family of lemon billiard systems. The classical phase space of our system consists of regular and irregular regions. We determine an analytic solution of the phase volume for these regions as a function of the system parameter and show that the function reveals a cusp singularity at the bifurcation point. The function is compared with its quantum mechanical counterpart, the Berry-Robnik parameter. By estimating the semiclassical regime from the effective Planck constant that validates the quantum-classical correspondence of the Berry-Robnik parameter, we determine a region of the system parameter where the cusp can be reproduced by the statistical properties of the eigenenergy levels.

[Alkylation of gem-dibromocyclopropanes with higher-order organocuprates].

The reaction of gem-dibromocyclopropanes (1) with a higher-order organ-ocuprate prepared from CuCN and commercially available MeLi, followed by the addition of MeI in situ, afforded dimethylcyclopropanes (2) in good yields. The differential substitution reaction of dibromide (1a) in one pot with the higher-order organocuprate and allyl bromide gave a compound (8) in the moderate selectivity as shown in Table 3. Its stereochemistry was deduced by the reaction mechanism.

On the conversion of thymidine phosphate bromohydrins to thymidine phosphates: a model reaction for the repair of oxidized nucleotides.

Bromohydrins (12, 13, and 14), which were oxidatively damaged products of thymidine nucleotides, were repaired by the action of sunlight (2700 lux) or heat via a radical mechanism to regenerate the original nucleotides (8,9, and 10). A significant effect of 3',5'-phosphate linkage on the repair reactions to natural type of thymidine nucleotide was proposed.

[Baeyer-Villiger reaction of benzaldehydes possessing oxygen functions with SeO2-H2O2].

The Baeyer-Villiger (B. V.) reaction using SeO2-H2O2 was examined for various benzaldehydes possessing methoxy groups and/or a furan ring. When benzaldehydes have an electron-donating group (methoxy group) at the ortho or para position to a formyl group, the B. V. reaction proceeded rapidly and in a good yield. Since the reaction using SeO2-H2O2 is carried out under a neutral condition, this reaction are applicable to aldehyde derivatives with a furan ring which is unstable against acid.

Chaos mirror for free-space links.

We propose a novel reflector, called a chaos mirror, designed by use of the principles of chaotic reflection. A feature of the reflector is that it converts a one-dimensional spread of incident rays into a two-dimensional spread of reflected rays. This can be useful for making free-space optical beam links by sweeping a transmission beam in only one dimension.

On the cross-coupling reaction of 1,3-dimethylthymine and thymidine epoxides with nucleophiles.

Solvent effect in reaction of 1,3-dimethylthymine epoxide (1) with amines was investigated. The results are summarized in Table I, indicating that the ratio of formation of the cis product (2) increases as a solvent becomes more polar. Reaction of thymidine epoxide (5) with nucleophiles was also examined.

On the reactions of DL-1,3-dimethylthymine epoxide with amines and L-amino acid derivatives.

Reaction of DL-1,3-dimethylthymine epoxide (1) with aniline gave (2A) and (3A). Isomerization of (2A) provided (3A), (4) and (5). Reaction of (1) with L-amino acid ethyl ester afforded four optically active diastereomers.

Studies on oxidative modifications of nucleic acid pyrimidine bases.

Oxidation of diacetylthymidine (4), triacetyluridine (5), and 5-fluoro-1,3-dimethyluracil (3) with m-chloroperbenzoic acid and cross-linkage of the bromohydrin (6) with the benzylamine and glycine ethyl ester are described. A Plausible mechanism for formation of oxidation products is also presented.

On the repair of thymidine bromohydrins, damaged nucleosides: a possible new model for the damage and repair of nucleic acids.

Bromohydrins, which were damaged products of thymidines (2, 3, and 4), were repaired with sunlight or heat via a radical mechanism to regenerate the thymidines. A hypothesis for the biological significance of thymidine in DNA is presented.

On the repair of thymine and thymidine bromohydrins: a possible new model for the damage and repair of nucleic acids.

Bromohydrins (2, 3, 4, and 5), oxidatively damaged products of thymine bases, were repaired on exposure to sunlight, heat, and/or some reagents to regenerate the thymine bases. A radical mechanism is proposed for the repair reaction with sunlight and heat. A hypothesis concerning the biological significance of thymidine in deoxyribonucleic acid is presented.