| Nucleoplasmic bridges(NPB) is a cytogenetics indicator for ionizing radiation by the cytokinesis block method (Cytokinesis-block analysis, CB),observed in human peripheral blood lymphocytes,which is an abnormal karyoplasm connection between the two main nucleuses.NPB is a biomarker of chromosome damage induced by ionizing radiation, and the formation mechanism is DNA breakage, DNA repair,chromosome rearrangement and telomere terminal fusion. The spontaneous frequency of NPB is lower, and good dose-response relationship between the NPB and radiation dose,and the experimental operation steps is simple,can be evaluated by using an unified standard. Moreover, under the same experimental conditions,the NPB level is positivelyassociated with dicentric chromosome and centric ring(Dicentic chromosome + Centric ring, dic+r) after human peripheral blood lymphocyte were irradiated, suggesting that NPB has become a potential radiation biological dosimeter.This study uses the CB method to investigate the effect of gender and age on the level of NPB in normal population, and the effect of age, gender, and smoking factors on the level of NPB induced by radiation in normal peripheral blood lymphocyte, in order to further provide the research basis for NPB becomes a radiation biological dosimeter.Materials and methods1. The peripheral blood samples of 117 normal subjects were (60male and 57 female) collectedfor the analysis of the background level of NPB in the normal population; and the peripheral blood samples of 48 normal subjects (24 male and 24 female) were collectedfor the analysis of NPB and MN levels after induced by 2 Gy 60Co?-rays.2. CB method was used to analysis the background level of NPB of normal population, and the NPB and MN frequencies after induced by 2 Gy 60Co? rays.Combined with the influence of gender and age on NPB background level in the normal population, further explore the influence of gender, age and smoking and other factors on NPB level of human peripheral blood lymphocytes after induced by 2 Gy 60Co-y rays in the normal population.Result1. The effect of gender and age on NPB and MN background level in normal subjects(1) The CB samples of peripheral blood lymphocytes in 117 healthy subjects was analyzed, the spontaneous frequencyof NPB is (0.45±0.22) ×10-3/cell, and the MN is(14.65 ±6.30) ×10-3/cell.(2) The spontaneous frequency of NPB in male ((0.52± 0.11) ×10-3 / cells)is higher thanthat in female ((0.31 ±0.21) ×10-3/ cell), indicating there is statisticallysignificant differences between gender (U= 3.13, P< 0.01); The spontaneous frequency of MN in female((15.39 + 8.44) ×10-3 / cell) was higher than that in male ((13.88 + 4.53) ×10-2 cell), also show significant difference between gender (U= -2.46, P < 0.05).(3) NPB and MN background frequencies were increased with age in male subjects (average 41.72±11.85 years old). The NPB background levels were statisticallysignificant differences only between 20-years group and the 40-,50-years group; except the comparison of between 40-years group and 50-years group, the MN background levels were statistically significant differences between any two groups.(4) 40-age group has the highest background levels of NPB in female subjects(average 40.31±11.91 years old), and there were significant differences with the 20-years group and 30- years group (U=2.88, p<0.01;U=2.37,P<0.05), among other age groups there was no significant difference; The background levels of MN increased with age in female subjects, except the comparison of between 40-years group and 50-years group, the MN background levels were statistically significant differences between any two groups (U=6.99, P<0.01; U=10.66,p<0.01).2. The influence of gender, age, smoking on NPB and MN levels in peripheral blood lymphocytes of healthy subjects induced by 2 Gy 60Co?-rays(1) 48 subjects with an average age of 40.60±10.31 years, the mean value of NPB exposed to 2Gy 60Co?-rays in human peripheral blood lymphocytes is(34.51 ± 11.66) ×10-3 /cell,and of MN is (318.45±77.42) ×10-3/ cell.(2) The frequency value of NPB in female ((34.80±10.50)×10-3 /cell) was higher than in male( (34.19±13.00)×10-3 /cell) induced by 2 Gy 60Co-? rays in human peripheral blood lymphocytes,but showed no statistically significant difference in sexuality (U=-0.54, p>0.05).(3) The frequency value of NPB was highest in 40-years group, and showed significant difference with 20-, 30- and 50-years group, while increasing tendency has no correlation with age (U=2.33,P<0.05; U=2.43 p<0.05; U=2.68,p<0.01).(4)Exposed to 2 Gy 60Co-y rays in human peripheral blood lymphocytes, the mean frequency value of NPB of smoking group ((33.70 ± 5.99) ×10-3 /cell)) was lower than non-smoking group ((34.60 ± 12.19) ×10-3/cell),but no statistics difference(P>0.05); The mean frequency value MN of smoking group (281.60 ± 41.35)X 10-3 /cell) was lower than non-smoking group ((322.73 ±79.78) ×10-3/cell),indicating there is statisticallysignificant differences between gender (U= -7.28, p<0.01).Conclusion1. Spontaneous rate of NPB is low, the background level of NPB was slightly higher in male than that of female, and there were statisticallysignificant differences,suggesting that gender has a potential impact on the background level of NPB.2.The background levels of NPB in healthy male showed increasing with age,40-age group has the highest background levels of NPB in female subjects, and there were statisticallysignificant differences among the different age groups, presenting that age has some influence on the background level of NPB.3. Smoking factor has no significant effect on the incidence of NPB level induced by 2 Gy 60Co-? rays in human peripheral blood lymphocytes.4. Gender has no significant influence on the incidence of NPB level induced by 2 Gy 60Co-? rays in human peripheral blood lymphocytes.5. 40-age group background levels of NPB were statistical differences with other any age groups, presenting that age has some influence on the level of NPB induced by 2 Gy 60Co-? rays in human peripheral blood lymphocytes.The spontaneous frequency of NPBis influenced by gender and age. There is no effect between the frequency of NPB and gender or smokeexcept ageexposed to ionizing radiation. In the present study, we suggest that we should consider the factors with gender and age to evelue high dose ionizing radiation byNPB as a biology dosimeter, and for low dose ionizing radiation, we should take account of gender and years of age. |
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