Official multiresidue methods of pesticide analysis in vegetables, fruits and soil.

Many different types of pesticides are used extensively on fruits and vegetables. The present contribution represents an overview of the multiresidue methods of analysis of the most widely used pesticides.

Relationship between tumor (T) antigen expression and substituent effects on benzo [a] phenothiazines.

Human adenovirus, oncogene-type 12 infected HEp-2 cells were exposed to six benzo[a]phenothiazines. 5-Oxo-5H-benzo[a]phenothiazine (4) and 6-hydroxy-5-oxo-5H-benzo[a]phenothiazine (5) were moderately toxic. 9-Methyl-12H-benzo[a]phenothiazine (2), 10-methyl-12H-benzo[a]phenothiazine (3), 6-methyl-5-oxo-5H-benzo[a]phenothiazine (6), and 12H-benzo[a]phenothiazine (1) were not toxic in the system tested. 6-Methyl-5-oxo-5H-benzo[a]phenothiazine (6) enhanced the expression of viral oncogene product (tumor antigen) in the adenovirus infected cells. 5-Oxo-5H-benzo[a]phenothiazine (4) and 6-hydroxy-5-oxo-5H-benzo[a]phenothiazine (5) reduced this effect. 6-Methyl-5-oxo-5H-benzo[a]phenothiazine (6), with hyperconjugation due to the methyl group, increased the T antigen activity at higher dose concentrations, whereas 6-hydroxy-5-oxo-5H-benzo[a]phenothiazine (5) with a hydroxy substituent had the opposite effect on T antigen expression. The methyl substitution at positions C9 or C10 increased the T antigen expression of adenovirus infected cells.

Antimutagenicity of benzo[a]phenothiazines in chemically induced mutagenesis.

The antimutagenicity of seven benzo[a]phenothiazines was screened against Salmonella typhimurium strain TA98 treated with 4-nitro-o-phenylenediamine which is a specific mutagen to the strain, and the results were compared to the antimutagenic activity of chlorpromazine (8), one of the 2-chlorophenothiazine derivatives-which have been shown to be the most effective mutagen inhibitors. Benzo[a]phenothiazines with methyl, oxo or hydroxyl substituent(s) at position 5, 6, 9 or 10 were used in the screening tests. 6-Hydroxy-5-oxo-5H-benzo[a]phenothiazine (6) reduced the induced mutation by 27%, being a more potent antimutagenic agent than chlorpromazine (8). The study of antimutagenicity is of great interest for the development of cancer chemopreventive agents which stop cancer progression in multistage carcinogenesis in which successive mutation sequences are required for a progression into full-fledged metastatic cancer.

Supercritical fluid extraction for the analysis of pesticide residues in miscellaneous samples.

Supercritical fluid extraction (SFE) procedures for pesticide residue analysis are reviewed and discussed. A variety of applications were classified, on matrices such as fruits, vegetables, soils, biological tissues, and other materials. Emphasis is placed on analysis of samples with a high water content containing polar pesticides, with particular attention paid to the multiresidue analyses.

Seventeenth Annual Interdisciplinary Cancer Research Workshop.

The Seventeenth Annual Interdisciplinary Cancer Research Workshop was held at the University of New Orleans on March 4, 1994. It was again sponsored by the Cancer Association of Greater New Orleans, a United Way Agency. As all the previous workshops in this highly successful series, it was organized by Peter Politzer (University of New Orleans), with the assistance of Anita H. Buckel (University of New Orleans) and James R. Jeter (Tulane University School of Medicine, New Orleans). The three invited speakers were Robert J. Coffey (Vanderbilt University, Nashville, TN), Suzanne A. W. Fuqua (University of Texas Health Science Center, San Antonio, TX), and Frank M. Torti (Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC). A one-hour-discussion period in the afternoon presented ample opportunity for an exchange of ideas and research findings among the speakers and the workshop participants. James R. Jeter served as the moderator of this lively discussion session.

Eighteenth Annual Interdisciplinary Cancer Research Workshop.

The Eighteen Annual Interdisciplinary Cancer Research Workshop was another one in a highly successful series of these New Orleans workshops. It was held on March 3, 1995, in a new location-at the J. Bennett Johnston Building of the Tulane University Medical Center. With a single exception, all the previous workshops took place at the University of New Orleans. Similarly, as all the past workshops, it was sponsored by the Cancer Association of Greater New Orleans, a United Way Agency. It was again organized by Peter Politzer (University of New Orleans), with the assistance of Anita H. Buckel (University of New Orleans) and James R. Jeter (Tulane University School of Medicine, New Orleans). The three invited speakers were William N. Hait (The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ), Joachim G. Liehr (Department of Pharmacology & Toxicology, The University of Texas Medical Branch at Galveston, Galveston, TX), and Patrice C. Ferriola (Department of Cell and Molecular Toxicology, Chemical Industry Institute of Toxicology, Research Triangle Park, NC). A one-hour discussion period after the conclusion of the last presentation represented an excellent forum for an exchange of ideas and research results among the speakers and the workshop participants. Lee Roy Morgan (Dekk-Tec, New Orleans) served as the moderator of the discussion session.

Quantitative treatment of the effect of solvent on the electronic absorption and fluorescence spectra of substituted coumarins: Evaluation of the first excited singlet-state dipole moments.

The electronic absorption and fluorescence spectra of coumarin and 11 substituted coumarins were measured in several solvents (dioxane, ethyl ether, ethyl acetate, ethanol, dimethylformamide, acetonitrile, and dimethyl sulfoxide). Ground-state dipole moments were determined in dioxane at 298 K. The results were used to obtain the first excited singlet-state dipole moments of the coumarins under study by the solvatochromic shift method (Bakhshiev, Kawski-Chamma-Viallet, McRae, and Suppan correlations). Also, the ground- and the first excited singlet-state dipole moments were calculated using a combination of the PPP method (π-contribution) and the vector sum of the σ-bond and group moments (σ-contribution). In general, the first excited singlet-state dipole moments of the coumarins are noticeably higher than the corresponding ground-state values, indicating a substantial redistribution of theπ-electron densities resulting in a more polar excited state. There is a reasonably good agreement between the calculated and the experimental dipole moments.