Subject(s)
Escherichia coli Proteins/physiology , Escherichia coli/radiation effects , Glutathione Synthase/physiology , Radiation Tolerance/genetics , Thioredoxin-Disulfide Reductase/physiology , Thioredoxins/physiology , Ultraviolet Rays , Escherichia coli/enzymology , Escherichia coli/genetics , Escherichia coli Proteins/genetics , Gene Expression Regulation, Bacterial , Glutathione Synthase/genetics , SOS Response, Genetics/genetics , Thioredoxin-Disulfide Reductase/genetics , Thioredoxins/geneticsABSTRACT
The effect of mutations in the genes encoding glutathione, glutaredoxin, thioredoxin, and thioredoxin reductase on the response of growing Escherichia coli to oxidative stress was studied. The gshA mutants defective in glutathione synthesis had the lowest resistance to high doses of H2O2, whereas the trxB mutants defective in thioredoxin reductase synthesis had the highest resistance to this oxidant, exceeding that of the parent strain. Among the studied mutants, the trxB cells demonstrated the highest basic levels of catalase activity and intracellular glutathione; they were able to rapidly reach the normal GSH level after oxidative stress. At the same time, these bacteria showed high frequency of induced mutations. The expression of the katG and sulA genes suggests that, having different sensitivity to high oxidant concentrations, the studied mutants differ primarily in their ability to induce the antioxidant genes of the OxyR and SOS regulons.
Subject(s)
Escherichia coli/physiology , Oxidative Stress , Peroxides , DNA-Binding Proteins/genetics , Escherichia coli Proteins/genetics , Escherichia coli Proteins/physiology , Gene Expression Regulation, Bacterial , Genes, Bacterial/genetics , Glutaredoxins/physiology , Glutathione/physiology , Mutation , Oxidation-Reduction , Regulon , Repressor Proteins/genetics , SOS Response, Genetics/genetics , Thioredoxin-Disulfide Reductase/physiology , Thioredoxins/physiology , Transcription Factors/geneticsABSTRACT
Major heart tone amplitude-frequency characteristics were studied in relation to central hemodynamics and physical stress tolerance in 147 chronic coronary patients. A method of spectrogram assessment is proposed that includes the measurement of spectrum width, resonance frequency and the Q-factor. Amplitude-frequency studies demonstrated limited left-ventricular vibration capacity with reduced myocardial contractility and increased myocardial weight. The results of bicycle ergometry were correlated with heart tone spectrum data. A relationship was demonstrated between changes in major parameters of tone 1 and the double product, threshold capacity for exercise and the output.
