Evaluation of the toxic effect of the herbicide 2, 4-D on rat hepatocytes: an FT-IR spectroscopic study.

Infrared spectroscopy is a powerful technique used to investigate molecular structures to the level of bond lengths and angles. In this study, the hepatotoxic effect of 2, 4-dichlorophenoxyacetic acid (2, 4-D) was investigated using Fourier transform infrared (FT-IR) spectroscopy. The experiment was performed on 15 male albino Wister rats (250-350 g) divided randomly into a control group (5 rats) and 2, 4-D-treated group (10 rats). The 2, 4-D-treated group received a single oral gavage LD50 dose of 639 mg/kg body weight; the rats were then killed and the livers excised 24 h after 2, 4-D administration. Spectroscopic results revealed that there was a significant reduction in protein content as well as a marked decrease in the secondary structure of protein after 2, 4-D intoxication. Moreover, looseness of membrane lipid chain packing, lipid polarity and/or significant increases in the formation of lipids with hydroperoxyl groups and carbonyl compounds were shown in the 2, 4-D LD50-treated group compared to the control group. Glycogen is dramatically decreased in rat liver after the induction of 2, 4-D. In conclusion, FTIR spectroscopy proved to be a rapid and sensitive approach to cytotoxicity diagnosis and monitoring of toxin-induced damage in biological membranes and proteins. In addition, the FTIR parameters employed in this study can be used as biophysical indicators of toxin-induced cell or membrane damage during apoptosis.

Effect of Very Low Dose Fast Neutrons on the DNA of Rats' Peripheral Blood Mononuclear Cells and Leukocytes.

The effect of very low dose fast neutrons on the chromatin and DNA of rats' peripheral blood mononuclear cells (PBMC) and leukocytes has been studied in the present work using Fourier transform infrared (FTIR) and single-cell gel electrophoresis (comet assay). Fourteen female Wistar rats were used; seven were irradiated with neutrons of 0.9 cGy (Am-Be, 0.02 cGy h(-1)), and seven others were used as control. Second derivative and curve fitting were used to analyze the FTIR spectra. In addition, hierarchical cluster analysis (HCA) was used to classify the group spectra. Meanwhile, the tail moment and percentage of DNA in the tail were used as indicators to sense the breaking and the level of damage in DNA. The analysis of FTIR spectra of the PBMC of the irradiated group revealed a marked increase in the area of phosphodiesters of nucleic acids and the area ratios of RNA/DNA and phosphodiesters/carbohydrates. A sharp significant increase and decrease in the areas of RNA and DNA ribose were recorded, respectively. In the irradiated group, leukocytes with different tail lengths were observed. The distributions of tail moments and the percentage of DNA in the tail of irradiated groups were heterogeneous. The mean value of the percentages of DNA in the tail at 0.5 h post-irradiation represented low-level damage in the DNA. Therefore, one can conclude that very low dose fast neutrons might cause changes in the DNA of PBMC at the submolecular level. It could cause low-level damage, double-strand break, and chromatin fragmentation of DNA of leukocytes.

Effects of Very Low Dose Fast Neutrons on Cell Membrane And Secondary Protein Structure in Rat Erythrocytes.

The effects of ionizing radiation on biological cells have been reported in several literatures. Most of them were mainly concerned with doses greater than 0.01 Gy and were also concerned with gamma rays. On the other hand, the studies on very low dose fast neutrons (VLDFN) are rare. In this study, we have investigated the effects of VLDFN on cell membrane and protein secondary structure of rat erythrocytes. Twelve female Wistar rats were irradiated with neutrons of total dose 0.009 Gy (241Am-Be, 0.2 mGy/h) and twelve others were used as control. Blood samples were taken at the 0, 4th, 8th, and 12th days postirradiation. Fourier transform infrared (FTIR) spectra of rat erythrocytes were recorded. Second derivative and curve fitting were used to analysis FTIR spectra. Hierarchical cluster analysis (HCA) was used to classify group spectra. The second derivative and curve fitting of FTIR spectra revealed that the most significant alterations in the cell membrane and protein secondary structure upon neutron irradiation were detected after 4 days postirradiation. The increase in membrane polarity, phospholipids chain length, packing, and unsaturation were noticed from the corresponding measured FTIR area ratios. This may be due to the membrane lipid peroxidation. The observed band shift in the CH2 stretching bands toward the lower frequencies may be associated with the decrease in membrane fluidity. The curve fitting of the amide I revealed an increase in the percentage area of α-helix opposing a decrease in the ß-structure protein secondary structure, which may be attributed to protein denaturation. The results provide detailed insights into the VLDFN effects on erythrocytes. VLDFN can cause an oxidative stress to the irradiated erythrocytes, which appears clearly after 4 days postirradiation.