[The effect of peroxiredoxin 2 on transforming growth factor-β1-induced fibroblast proliferation and collagen synthesis]

Objective: To investigate the effect of peroxiredoxin 2 (Prx2) overexpression on fibroblast proliferation and collagen synthesis induced by transforming growth factor-β1 (TGF-β1) . Methods: Fibroblasts were randomly divided into control group (DMEM medium) , TGF-β1 group (5 μg/L TGF-β1) , negative control group (treated with 5 μg/L TGF-β1 and transfected with empty lentiviral vector) , and Prx2 group (treated with 5 μg/L TGF-β1 and transfected with Prx2 overexpression lentiviral vector) . MTT assay was used to measure cell proliferation, immunofluorescence assay was used to measure the expression of 8-OHdG, and Western blot was used to measure the expression of p-JNK, p-P38, collagen type I, collagen type III, and Prx2. SPSS 18.0 was used for statistical analysis. The continuous data were expressed as mean±standard deviation; an analysis of variance was used for comparison between groups, and the least significant difference t-test was used for further comparison between two groups. Results: Lentiviral transfection was performed successfully, and the Prx2 group had a significant increase in the protein expression of Prx2 (P<0.05) . Compared with the control group, the TGF-β1 group had a significant increase in the proliferation ability (P<0.05) , and compared with the TGF-β1 group, the Prx2 group had a significant reduction in the proliferation ability (P<0.05) . Compared with the control group, the TGF-β1 group had significant increases in the expression of 8-OHdG, p-JNK, p-P38, collagen type I, and collagen type III (P<0.05) ; compared with the TGF-β1 group, the negative control group had no significant changes in the expression of 8-OHdG, p-JNK, p-P38, collagen type I, and collagen type III (P>0.05) , while the Prx2 group had significant reductions in the above parameters (P<0.05) . Conclusion: Prx2 overexpression inhibits fibroblast proliferation and collagen synthesis induced by TGF-β1 through inhibiting reactive oxygen species and activating the JNK and P38 pathways.

Synergism of insecticides by herbicides: effect of environmental factors

The synergism of parathion and p,p'-DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane] by atrazine was investigated as a function of soil type, age of pesticide soil residues, and the presence of soils in quiet or turbulent water. Compared to previous tests in which the pesticides were applied on glass surfaces, a significant reduction of the toxicity of the insecticides to fruit flies and of the synergistic effects of atrazine was observed with soils, particularly a silt loam. The effects of atrazine as a synergist in soil declined rapidly within 4 days. The toxicity of parathion in water and its synergism by atrazine were significantly reduced by soil sediments, depending on the type and amount of soil present. Soils were highly effective in turbulent water: in water containing the relatively high parathion concentration of 0.3 part per million, 93 percent of the mosquito larvae present died within 24 hours, yet this solution was rendered nontoxic by being mixed with 5 grams of a loam soil. With atrazine present in the latter system, however, 38 percent of the mosquito larvae died. Thus, insecticides can be more or less toxic, depending on their concentrations, the presence of synergists, and the environmenetal conditions.

Synergism of insecticides by herbicides

The herbicides atrazine, simazine, monuron, and 2,4-D (2,4-dichlorophenoxyacetic acid) enhanced the toxicity of selected insecticides to Drosophila melanogaster Meigen, Musca domestica L., and larvae of Aedes aegypti L. The insecticides-nine organophosphorus compounds, two chlorinated hydrocarbons, and one carbamate-were used at dosages that resulted in low insect mortalities, while the herbicides by themselves were nontoxic. Atrazine was most effective. With increasing amounts of this herbicide and constant amounts of some insecticides, increasing mortalities of fruit flies were observed. Exposure of the insects for 24 hours to carbofuran (0.5 microgram), p,p'-DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] (4 micrograms), parathion (0.35 microgram), and diazinon (0.2 microgram) alone resulted in mortalities of 7.5, 9.5, 8, and 10.5 percent, respectively. Based on dosage mortality curves obtained with increasing amounts of atrazine, mortalities of 50 percent of the insect populations would have been achieved with 23, 40, 6, and 10 micrograms of atrazine added to the abovementioned dosages of carbofuran, DDT, parathion, and diazinon, respectively.