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Nitric oxide detection in cell culture exposed to LPS after Er:YAG laser irradiation
R A S S Rocha1, R A B Silva, S Assed
1Department of Paediatric, Preventive and Community Dentistry, Dental School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
Aim:
To evaluate in vitro the effect of calcium hydroxide [Ca(OH)(2)] and Er:YAG laser on bacterial endotoxin [also known as lipopolysaccharide (LPS)] as determined by nitric oxide (NO) detection in J774 murine macrophage cell line culture.
Methodology:
Samples of LPS solution (50 microg mL(-1)), Ca(OH)(2) suspension (25 mg mL(-1)) and LPS suspension with Ca(OH)(2) were prepared. The studied groups were: I - LPS (control); II - LPS + Ca(OH)(2); III - LPS + Er:YAG laser (15 Hz 140 mJ); IV - LPS + Er:YAG laser (15 Hz 200 mJ); V - LPS + Er:YAG laser (15 Hz 250 mJ), VI - Pyrogen-free water; VII - Ca(OH)(2). Murine macrophage J774 cells were plated and 10 microL of the samples were added to each well. The supernatants were collected for NO detection by the Griess reaction. Data were analysed statistically by one-way anova and Tukey's test at 5% significance level.
Results:
The mean and SE (in micromol L(-1)) values of NO release were: I - 10.48 +/- 0.58, II - 6.41 +/- 0.90, III - 10.2 +/- 0.60, IV - 8.35 +/- 0.40, V - 10.40 +/- 0.53, VI - 3.75 +/- 0.70, VII - 6.44 +/- 0.60; and the values for the same experiment repeated after 1 week were: I - 21.20 +/- 1.50, II - 9.10 +/- 0.60, III - 19.50 +/- 1.00, IV - 18.50 +/- 0.60, V - 21.30 +/- 0.90, VI - 2.00+/- 0.20, VII - 6.80 +/- 1.70. There was no significant difference (P > 0.05) between the control and the laser-treated groups (III, IV and V), or comparing groups II, VI and VII to each other (P > 0.05). Group I had significantly higher NO release than group II (P < 0.05). Groups II and VI had similar NO release (P > 0.05).
Conclusions:
Calcium hydroxide inactivated the bacterial endotoxin (LPS) whereas none of the Er:YAG laser parameter settings had the same effectiveness.
