The effect of aging on micronuclei frequency and proliferation in human peripheral blood lymphocytes.

INTRODUCTION: Increase in the instability of cellular genome with an increasing age is the result of an accumulation of cellular damage and mutations. This instability which might be observed as chromosome damage or chromosome losses can be measured by the micronucleus technique. AIM: The aim of this study was to investigate the effect of aging and oxidative stress induced by non-toxic levels of H(2)O(2) on micronuclei induction and their relationship to cell proliferation in human peripheral blood lymphocytes. MATERIALS AND METHODS: Healthy volunteers with different ages were choosen. Spontaneous and H(2)O(2) induced micronuclei frequencies were measured in peripheral blood lymphocytes of 30 volunteers by the micronucleus method. RESULTS: Spontaneous micronuclei frequencies increased first then started to decrease after 50 years of age. This biphasic response was significantly higher than micronucleus (MN) frequencies induced by H(2)O(2) (P < 0.05), which followed the similar shape of response to increasing ages with lower frequencies. Proliferative capacity of cells either treated with H(2)O(2) or not did not differ with an increasing age giving similar responses. CONCLUSION: These results indicate biphasic character of chromosome damage; first increase and decrease after 50 years with an increasing age. But this change pattern was not correlated with the steady state of proliferation capacity of cells through an increasing age. Decreases in H(2)O(2)-induced MN frequencies compared to spontaneous MN frequencies may be inducing an apoptosis by H(2)O(2) treatment leading to underscoring damaged cells.

Ecophysiological and seasonal variations in Cd, Pb, Zn, and Ni concentrations in the leaves of urban deciduous trees in Istanbul.

The concentrations of Cd, Pb, Zn and Ni were measured in the leaves of 7 species of deciduous trees, from the urban sites of Istanbul, in both the Spring and Autumn seasons. We detected some differences in the heavy metal concentrations of the control and urban site samples of identical species. Highest concentrations of Cd were detected in Populus, Pb in Aesculus and Robinia, Zn in Populus, and Ni in Robinia and Fraxinus. Lowest chlorophyll content and highest peroxidase (POD) activity was found in the urban site samples of Acer. We have found a positive correlation between the increase in the POD activity and the Pb concentration in Populus. Generally, the tree species investigated in this study, are considered to have different tolerance levels to heavy metal pollution. The data obtained show that the chlorophyll content and the POD activity may be used as heavy metal stress biomarkers in the urban trees.

Can micronucleus technique predict the risk of lung cancer in smokers?

Smoking is the main etiological factor in the carcinogenesis process of lung cancer. But genetically defined factors such as increased levels of oxidase enzymes or chromosome aberrations have been shown to correlate with the higher possibility of contracting lung cancer among smokers. In this study, chromosome aberrations measured by micronucleus (MN) technique following in vitro irradiation were investigated in peripheral blood lymphocytes of long term smokers with or without lung cancer. Our aim is to establish the role of MN scores in identifying the individuals who might develop cancer among smokers. Twelve lung cancer patients and appropriately matching 10 healthy controls were evaluated. Spontaneous and radiation induced MN frequencies were evaluated in the two groups. An increase in the amounts of MN after 3 Gy irradiation was observed in the patient and control group when compared to spontaneous frequencies. Absolute MN frequencies as a determinant of radiosensitivity were calculated by subtraction of spontaneous aberration frequencies from the frequencies that were obtained following 3 Gy of irradiation. Absolute MN frequency range was between 0.0116 and 0.3883 with the average value of 0.1114 +/- 0.0390 (SE) for the lung cancer patients, and was between 0.0216 and 0.2291 with the average value of 0.1410 +/- 0.0234 (SE) for the controls. When the comparison was made between the absolute MN frequencies of both groups, there was no difference (p=0.159) between the two groups. In our study, it can be concluded that radiation induced MN scores in peripheral blood lymphocytes of long term smokers do not predict the risk of lung cancer.