Visualization of irreparable XXXX in brain by selective labeling of double strand blunt-ended DNA breaks.

@entity64 @entity2806 @entity39 @entity63 @entity10371 @entity35
BACKGROUND: Double-strand DNA breaks with blunt ends represent the most serious type of DNA damage, and cannot be efficiently repaired by cells. They are generated in apoptosis or @entity39 and are absent in normal or transiently damaged cells. Consequently, they can be used as a molecular marker of irreparable cellular damage. We evaluated the effects of focal @entity2806 using selective labeling of blunt-ended DNA breaks as a marker of irreversible tissue damage. A new approach permitting such analysis in situ is introduced. MATERIALS AND METHODS: @entity35 brain sections taken 6, 24, 48 and 72 hr after the onset of focal @entity2806 were used. Double-strand DNA breaks were detected directly in the tissue sections via ligation of blunt-ended hairpin-shaped oligonucleotide probes. The probes were attached to the ends of the breaks by T4 DNA ligase. Conventional @entity10371 co-staining and terminal transferase based labeling (TUNEL) were employed to analyze the distribution of labeled cells. RESULTS: Double-strand blunt-ended DNA breaks rapidly accumulate in brain cells after focal @entity2806 . At 24 hr, they concentrate in the peripheral areas of @entity64 , which are prone to @entity63 -reoxygenation. By 48-72 hr, this type of DNA damage spreads inward, covering the internal areas of the @entity63 zone. CONCLUSIONS: Selective labeling of blunt-ended DNA breaks delineates the dynamics of @entity64 -induced irreversible DNA damage and provides highly specific detection of brain cells with irreparable DNA injury. It can be used for comparing the efficiency of various anti- @entity63 drugs, particularly those that target DNA damage, as well as for monitoring @entity64 -induced damage.
