Plasma homocysteine is associated with increased oxidative stress and antioxidant enzyme activity in welders.

The purpose of this study was to examine the association of vitamin B6 status and plasma homocysteine with oxidative stress and antioxidant capacities in welders. Workers were divided into either the welding exposure group (n = 57) or the nonexposure controls (n = 42) based on whether they were employed as welders. There were no significant differences in vitamin B6 status and plasma homocysteine concentration between the welding exposure group and the nonexposure controls. The welding exposure group had significantly higher levels of oxidized low-density lipoprotein cholesterol and lower erythrocyte glutathione concentration and superoxide dismutase (SOD) activities when compared to nonexposure controls. Plasma pyridoxal 5'-phosphate concentration did not correlate with oxidative stress indicators or antioxidant capacities in either group. However, plasma homocysteine significantly correlated with total antioxidant capacity (TAC) (partial r(s) = -0.34, P < 0.05) and erythrocyte SOD activities (partial r(s) = 0.29, P < 0.05) after adjusting for potential confounders in the welding exposure group. In the welding exposure group, adequate vitamin B6 status was not associated with oxidative stress or antioxidant capacities. However, elevated plasma homocysteine seemed to be a major contributing factor to antioxidant capacities (TAC and erythrocyte SOD activities) in welders.

Nanoscopic analysis on pH induced morphological changes of flagella in Escherichia coli.

BACKGROUND AND PURPOSE: Flagella contribute to the virulence of pathogenic bacteria through chemotaxis, motility, and adhesion. Understanding the various functions of flagella may provide insight into mechanisms of bacterial infection and transmission. The objectives of our study were to apply biophysical and biochemical methods to investigate the mechanisms of pH-dependent changes in flagella functions. METHODS: Atomic force microscopy (AFM) was used to analyze the flagellum morphology of Escherichia coli cultured in various pH conditions. The swarming plate method was used to identify pH-dependent changes in bacterial motility. Western blot analysis and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) were also carried out to study pH-dependent expression and structural changes of flagellin C. RESULTS: E coli cultured at pH 7 produced the flagella with the greatest average length and diameter. When the bacteria were grown at pH 6 or pH 8, shorter and thinner forms of flagella were produced. The morphology of the flagella was correlated to the bacterial motility. While western blot analysis showed only a slight change in the expression of the flagellin C protein in response to changes in the pH of the culture medium, ATR-FTIR showed significant pH-dependent changes in the secondary structure of the flagellin C assembled in sheared flagella. CONCLUSION: Our results show that both acidification and alkalization of the culture medium restricted bacterial motility, and indicate that the reduced motility may be caused by incorrect assembly of the flagellum proteins.