Reactive oxygen species inducible by low-intensity laser irradiation alter DNA synthesis in the haemopoietic cell line U937.
OBJECTIVE
The purpose of this study was to evaluate the possible role of reactive oxygen species (ROS) in mediating previously recorded alterations in DNA synthesis, inducible by low-intensity laser irradiation (LILI), in the haemopoietic cell line U937.


METHODS
The ability of LILI (660 nm, 12 mW, 5 kHz) to induce ROS from U937 cells was assessed spectrophotometrically at energy densities (E.D.) from 1.0 to 11.5 J/cm2. In order to assess whether laser-induced ROS could alter cellular proliferation DNA synthesis was measured post-irradiation, by the incorporation of tritiated thymidine (3H-TdR) into the cells in both the presence and absence of the antioxidant catalase (CAT).


RESULTS
Detectable ROS were produced post-irradiation only from the differentiated form of the cell line. Analysis by Student's t-test for unrelated groups showed a significant difference, at E.D.s 2.9 and 8.6 J/cm2, in the extent of DNA synthesis occurring in cells irradiated in the presence of CAT or in its absence.


CONCLUSIONS
These findings demonstrate that laser-inducible ROS can mediate laser's effects on this cell line.
Biotherapeutics Research Group, School of Biomedical Sciences, University of Ulster at Jordanstown, Northern Ireland.
G A
GA
Callaghan
C
C
Riordan
W S
WS
Gilmore
I A
IA
McIntyre
J M
JM
Allen
B M
BM
Hannigan
D002374:Catalase / Q000494:pharmacology; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis / Q000528:radiation effects*; D006412:Hematopoietic Stem Cells / Q000528:radiation effects*; D006861:Hydrogen Peroxide; D007834:Lasers; D017382:Reactive Oxygen Species / Q000502:physiology*; D013936:Thymidine / Q000378:metabolism
D017382:Reactive Oxygen Species; D004247:DNA; D006861:Hydrogen Peroxide; D002374:Catalase; D013936:Thymidine