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Detection of fragile sites induced by pyrimethamine

U Egeli1, B Tunca

  • 1Department of Medical Biology, Faculty of Medicine, University of Uludağ, Bursa, Turkey.

Insights

Pyrimethamine significantly increases chromosomal aberrations in human lymphocytes, revealing five new folic acid-sensitive fragile sites. This finding is crucial for understanding drug-induced genetic instability.

Area of Science:

  • Cytogenetics
  • Pharmacology
  • Human Genetics

Background:

  • Fragile sites are specific points on chromosomes prone to breakage.
  • Certain drugs can induce or enhance the expression of these fragile sites.
  • Understanding these mechanisms is vital for assessing genotoxicity and genetic risk.

Purpose of the Study:

  • To investigate the effect of pyrimethamine on inducing fragile sites in human peripheral blood lymphocytes.
  • To identify specific chromosomal locations of pyrimethamine-induced fragile sites.
  • To evaluate the potential genotoxic effects of pyrimethamine.

Main Methods:

  • Human peripheral blood lymphocyte cultures from 15 healthy individuals were established.
  • Cultures were treated with pyrimethamine (0.02 mg/ml) for 48 and 72 hours.
  • Chromosomal aberrations and fragile site localization (using G-banding and light microscopy) were analyzed.

Main Results:

  • A significant increase in cells with chromosomal aberrations was observed in pyrimethamine-treated cultures compared to controls (P < 0.001).
  • Five folic acid-sensitive fragile sites were identified and localized: 1p32, 1q32, 3p14, 6p22, and 14q24.
  • The study demonstrates pyrimethamine's capacity to induce fragile site expression.

Conclusions:

  • Pyrimethamine induces chromosomal instability and expression of fragile sites in human lymphocytes.
  • The identified fragile sites (1p32, 1q32, 3p14, 6p22, 14q24) are sensitive to folic acid.
  • These findings highlight the importance of considering pyrimethamine's genotoxic potential.

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