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BACKGROUND: The insecticidal activity of essential oil of Mentha piperita L. emend. Huds. against local mosquitoes as disease vectors was recognized and found to be due to the presence of menthol, which is the major aroma compound of the oil. The minor compounds of the oil, i.e. menthone, β-caryophyllene, menthyl acetate, limonene, α-pinene and pulegone, showed either less or no activity against the mosquitoes tested. L-Menthol derivatives were synthesized and their knockdown effect and mortality were evaluated against local mosquitoes of Culex quinquefasciatus Say, Aedes aegypti L. and Anopheles tessellatus Theobald as disease vectors. This is the first report of mosquitocidal activity of menthol and its derivatives against Cx. quinquefasciatus, Ae. aegypti and An. tessellatus. RESULTS: Derivative synthesis followed by structure–activity relationship studies identified several derivatives, i.e. menthyl chloroacetate, menthyl dichloroacetate, menthyl cinnamate, menthone glyceryl acetal, thymol, α-terpineol and mugetanol, with enhanced mosquitocidal activity against Cx. quinquefasciatus, Ae. aegypti and An. tessellatus relative to the parent compound L-menthone. CONCLUSION: In ester derivatives of L-menthol the optimum activity is dependent on the size and shape of the ester group and the presence of chlorine atoms in the ester group. In structurally related derivatives of L-menthol the optimum activity is dependent on the aromaticity, the degree of unsaturation, the position of the hydroxy group and the type of functional group. Copyright © 2007 Society of Chemical Industry

Culex quinquefasciatus Say from Saudi Arabia (Jpal-per) showed high levels of resistance (2,500-fold) to permethrin. A major contribution of cytochrome P450 monooxygenases as a mechanism of resistance was suggested by the large synergistic effects of oxidase inhibitors such as 2-propynyl 2,3,6-trichlorophenyl ether (PTPE) and piperonyl butoxide (PBO) on the toxicity of permethrin in the resistant strain. Contents of cytochrome P450 and b5 were about 2.5 times higher in the Jpal-per strain than those in the susceptible strain. P450 monooxygenase in the microsomes of gut and other parts of the body metabolized permethrin to 4′-HO-permethrin and other metabolites. Degradation of permethrin by microsomal P450 enzymes was much greater in the resistant Jpal-per strain and was inhibited by PBO and PTPE. In addition to a kdr type mechanism which seems to work in the larvae, cytochrome P450 monooxygenase is clearly shown to play an important role as a mechanism of permethrin resistance in Jpal-per strain larvae. Arch. Insect Biochem. Physiol. 37:47–56, 1998. © 1998 Wiley-Liss, Inc.

BACKGROUND. LL2 is a murine immunoglobulin (Ig)G2a-kappa anti-B-cell monoclonal antibody with proven targeting and therapeutic efficacy in the management of non-Hodgkin's lymphoma (NHL). The authors had previously generated a humanized LL2 (hLL2) that demonstrated binding properties identical to those of LL2. Nevertheless, the productivity of the cell line was insufficient for large-scale production of the antibody for clinical studies. Therefore, the authors chose an amplifiable system for the generation of hLL2. METHODS. The hLL2 sequences were ligated into the expression vector pdHL2, which has a dhfr amplifiable gene, and were incorporated into the SP2/0 cells by electroporation. A methotrexate (MTX) resistant clone producing hLL2 was identified. Stepwise increases in MTX concentrations, from 0.1 to 5 μM, and subcloning of the cells by limiting dilution were performed. RESULTS. By amplifying the dhfr and hLL2 genes with stepwise increases in the MTX concentration, the antibody production was enhanced from its original 1.4 to 70 ± 5 mg per liter of culture media. Subsequent subcloning further improved the productivity. Immunoreactivity of the antibody was conserved, as proven by enzyme-linked immunosorbent assay and cell-binding assays. By isoelectrofocusing, the isoelectric point (pI) of the antibody was measured at approximately 9.6. The productivity of the clone was not affected by culture conditions or storage of the cells in liquid nitrogen. CONCLUSIONS. By means of gene amplification, the authors have generated a high-producing hLL2-lgG clone suitable for production of the quantity of antibody necessary for clinical diagnostic and therapeutic trials of NHL patients.

Kinetic modelling is used in conjunction with measurements of product yields to develop a mechanism for the pyrolysis of ethylene at 896K and ethylene pressures ranging from approximately 3 to 78 kPa. An induction period was observed for all products except H2, and was followed by a steady rate, which was of second-order for all products except 1,3-C4H6, the most abundant product. The mechanism quantitatively accounts for the yields of H2, CH4, C2H6, C3H6, 1-C4H8 and 1,3-C4H6. The reaction is initiated by disproportionation of C2H4 and the product 1,3-C4H6 results from decomposition of the C4H7 radical, formed by addition of C2H3 to C2H4. The other organic products that were measured are formed as a result of reactions involving the C2H5 radical. The hydrogen is produced by abstraction from C2H4 by atomic hydrogen and its rate is controlled by the reaction C2H5 C2H4 + H which is nearly equilibrated. The main termination reaction is recombination of C2H5. The auto-acceleration which is evident particularly in the yields of H2, CH4, C2 H6, and C3H6 is accounted for by the decomposition of 1-C4H8. © 1996 John Wiley & Sons Inc.

Site directed mutagenesis/charged-to-alanine scanning mutagenesis of the amino terminal portion of human ERK2 (from amino acids 1 to 150) purified as a glutathione-S-transferase fusion protein (GST-ERK2) from E. coli has been done to determine regions/amino acids important for activation by rabbit skeletal muscle MAP kinase kinase (rMEK) and kinase activity towards myelin basic protein (MBP). Five classes of mutants have been isolated. The first class of mutants comprises of G30A/G32A, A50D and R65A/R68A/E69A, that can be phosphorylated by rMEK and have no kinase activity towards MBP, the second class includes mutants D122A/H123A and N142A which have lower kinase activities but no change in their activation by rMEK; third class being Y34A, E58A/H59A, which have neutral effect towards either activity, the fourth class that includes completely inactive mutants D42A/K46A/R48A, the deletion mutant in the same region (−9aa[40–48]) and D104A/E107A/D109A and finally the fifth class that include K53A, E94A/K97A/D99A, K112A/K115A and R133A/K136A that are phosphorylated 140–240% but with kinase activity toward MBP ranging from 50–100% of the wild type.

As part of a continuing study of factors influencing the development of pesticide resistance in insects, two new cytochrome P450s of the CYP6 family have been identified.

Ethylene at concentrations of 2.7 × 10−3 to 1.0 × 10−2 mol L−1 has been pyrolyzed at 900 K in a flow system. The products ethane and hydrogen have been analyzed by gas chromatography. The results are consistent with a mechanism in which these products are initially formed as follows: Reaction [1] occurs only 1 to 2% as often as the addition reaction, The latter reaction is close to equilibrium. Taking the rate constant, k4, and the equilibrium constant, K2, from the literature and making small adjustments for minor processes, k1 is found to be (9 ± 3) × 107 L mol−1 s−1. Here the uncertainty is intended to encompass errors in the present work and in the literature parameters. A secondary source of hydrogen was also observed. Its dependence on ethylene concentration was consistent with formation from an intermediate with six carbon atoms, such as cyclohexene.