engleski

Incidence of micronuclei in cytokinesis-blocked lymphocytes of medical personnel occupationally exposed to ultrasound

The in vitro micronucleus assay is used widely as a useful endpoint in biomonitoring and ecotoxicology, as well as for the assessment of in vitro and in vivo damage of chromosomal material caused by different mutagens. Up to date, little information about cytogenetic effects of occupational exposure to the ultrasound is avaliable. In order to investigate possible DNA damaging effects of ultrasonic waves on human genome, the micronucleus assay combined with Giemsa, DAPI and silver staining was performed. The subjects of study were medical staff daily occupationally exposed to pulsed wave color Doppler ultrasound in frequency2.5-7.5 MHz. The results obtained indicate increases in the total number of micronuclei and changes in their distribution in exposed subjects compared to control. Staining with DAPI and silver nitrate was used to distinguish micronuclei originating from breakage or mitotic loss of certain human chromosomes bearing DAPI-positively or silver-positively stained regions. Based on different intensity of DAPI staining signal-positive and signal-negative micronuclei were noticed, while silver staining has revealed AgNOR+ and AgNOR- micronuclei. In exposed subjects a prevalence in number of AgNOR+ over AgNOR- micronuclei compared to control was observed, indicating greater susceptibility of chromosomes from D and G groups to damage caused by continous occupationally exposure to ultrasound. In spite of their limitations, our results indicate that combination of conventional Giemsa staining of micronuclei with fluorescent dye DAPI and silver nitrate can be valuable complement to the standard micronucleus assay.

human lymphocytes; micronucleus assay; ultrasound; DAPI

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