Dose-Response: An International Journal: Volume 10, Issue 1
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2012-31-03
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Dose-Response Vol 10, no 1, Cover
(2012-03-01)
Dose-Response, Vol 10, no 1, Table of Contents
(2012-03-01)
ESTIMATION OF LIPID PEROXIDATION INDUCED BY HYDROGEN PEROXIDE IN CULTURED HUMAN LYMPHOCYTES
(2012-03-01) Siddique, Yasir Hasan; Ara, Gulshan; Afzal, Mohammas
Malondialdehyde (MDA) is used for the estimation of damage by reactive oxygen species. MDA is a major reactive aldehyde resulting from the peroxidation of biological membranes. The most common method used to assess MDA production is the thiobarbituric acid (TBARS) assay. However, the value of this method is curbed by low specificity and has been criticized for its use in human studies. In the present study we have used an alternative method for the estimation of MDA production i.e. reaction of MDA with a chromogenic agent 1-methyl-2-phenylindole at 45°C. The paper describes the method of preparing standards for the estimation of MDA (lipid peroxidation) after the treatment with an oxidative stress inducing agent hydrogen peroxide (H2O2). In the present study, the treatments of 1, 5, 10, 20, 50, 100, 150 and 200 μM of H2O2 induced significant increase in lipid peroxidation as compared to the untreated ones. The results suggest that the present method can be used to measure the lipid peroxidation in cultured human peripheral blood lymphocytes and is specific for MDA estimation.
NO EVIDENCE FOR THE IN VIVO INDUCTION OF GENOMIC INSTABILITY BY LOW DOSES OF 137CS GAMMA RAYS IN BONE MARROW CELLS OF BALB/CJ AND C57BL/6J MICE
(2012-01-01) Rithidech, Kanokporn Noy; Udomtanakunchai, Chatchanok; Honikel, Louise M; Whorton, Elbert B
In spite of extensive research, assessment of potential health risks associated with exposure to low-dose (≤ 0.1 Gy) radiation is still challenging. We evaluated the in vivo induction of genomic instability, expressed as late-occurring chromosome aberrations, in bone- marrow cells of two strains of mouse with different genetic background, i.e. the radiosensitive BALB/cJ and the radioresistant C57BL/6J strains following a whole-body exposure to varying doses of 137Cs gamma rays (0, 0.05, 0.1, and 1.0 Gy). A total of five mice per dose per strain were sacrificed at various times post-irradiation up to 6 months for sample collections. Three-color fluorescence in situ hybridization for mouse chromosomes 1, 2, and 3 was used for the analysis of stable-aberrations in metaphase-cells. All other visible gross structural-abnormalities involving non-painted-chromosomes were also evaluated on the same metaphase-cells used for scoring the stable-aberrations of painted-chromosomes. Our new data demonstrated in bone-marrow cells from both strains that low doses of low LET-radiation (as low as 0.05 Gy) are incapable of inducing genomic instability but are capable of reducing specific aberration-types below the spontaneous rate with time post- irradiation. However, the results showed the induction of genomic instability by 1.0 Gy of 137Cs gamma rays in the radiosensitive strain only.
ARE SOME NEURONS HYPERSENSITIVE TO METALLIC NANOPARTICLES?
(2012-01-01) Scott, Bobby R
Engineered metallic nanomaterial particles (MENAP) represent a significant break- through in developing new products for use by consumers and industry. Skin application (e.g., via creams and sprays containing nanoparticles) may provide a key route of potential intake of MENAP and can lead to retrograde transport from nerve endings in the skin to the somatosensory neurons in dorsal root ganglia (DRG). This paper uses a novel theoretical model (stochastic threshold microdose [STM] model) to characterize survival of DRG neurons exposed in cell culture replicates to copper nanoparticles, based on published data. Cell death via autophagy is assumed here to occur as a result of the uptake (called hits) of the nanoparticles by mitochondria. Theoretical results are presented for the existence of a hypersensitive fraction (about 20%) of neurons that are killed in significant numbers when on average > 1 hit to the at-risk mitochondria occurs. Further, most hypersensitive neurons appear to be killed by a cumulative exposure of about 2,000 micro- molar-hours and the remaining resistant cells may have dysfunctional mitochondria. Based on these theoretical findings, it is predicted that repeated exposure (e.g., over years) of the skin of humans to MENAP could lead to significant nervous system damage and related morbidity.