Effect of laser phototherapy on enzymatic activity of salivary glands of hamsters treated with 5-Fluorouracil

Does laser photobiomodulation prevent hyposalivation in patients undergoing head and neck radiotherapy? A systematic review and meta-analysis of controlled trials

INTRODUCTION

Head and neck radiotherapy can cause hypofunction of the salivary glands. Many studies report that laser photobiomodulation (PBM) is able to minimize radiation-induced hyposalivation, yet there is no consensus about its effects.

OBJECTIVE

To carry out a meta-analysis of controlled clinical trials that used PBM to prevent radiation-induced hyposalivation.

METHODS

A systematic search was performed through Embase, Medline/PubMed, Cochrane, EBSCO, Scopus, LILACS and Web of Science databases. The strategy included comparisons of the effect of PBM with placebo/clinical follow-up on unstimulated and/or stimulated salivary flow in patients undergoing head and neck radiotherapy.

RESULTS

Six clinical trials were included, five of which were used for meta-analysis. Evidence was observed between the use of PBM and increased unstimulated salivary flow (MD 0.20 mL/min, 95 % Cl 0.10-0.30, I² = 96 %, p < 0.00001) and in stimulated salivary flow (MD 0.27 mL/min, 95 % CI 0.08-0.46, I² = 95 %, p < 0.00001).

CONCLUSION

PBM appears to minimize radiation-induced hyposalivation.

Lactobacillus reuteri associated with scaling and root planing in the treatment of periodontitis in rats submitted to chemotherapy

OBJECTIVE

The aim of this study was to evaluate the effects of Lactobacillus reuteri applied locally or systemically with scaling and root planing (SRP) to the treatment of experimental periodontitis (EP) in rats treated with 5-fluorouracil.

METHODS

A cotton ligature was installed on the molars of rats. The animals (n = 54) underwent chemotherapy and were divided into groups: SRP (n = 18), scaling and root planing only; LP (n = 18), SRP and 4 sessions of local probiotic (PRO); SP, SRP and 4 sessions of systemic PRO. The molar furcation area was submitted to histopathological, histometric of alveolar bone loss (ABL) and immunolabeling analysis after euthanasia at 7, 15 and 30 days. The data were submitted to statistical analysis (α = 5%).

RESULTS

At 15 days ABL was higher in LP compared to SP. At 30 days, ABL was higher in LP compared to SRP and SP. Higher immunolabeling of TGF-β1 was observed in LP and SP at 7 days compared to SRP (p < 0.05). Lower immunolabeling of OCN and higher immunolabeling of RANKL were observed at all periods in SRP compared to SP (p < 0.05). At 30 days, SRP showed lower immunolabeling of OPG compared to SP and LP (p < 0.05). In SP, lower immunolabeling was observed at 15 days compared at 30 days (p < 0.05).

CONCLUSION

The ABL was similar among the groups treated with SRP associated or not to probiotic therapeutic, although the systemic use of Lactobacillus reuteri considerably reduced inflammation and favored periodontal tissues repair.

Intravenous laser wavelength radiation effect on LCAT, PON1, catalase, and FRAP in diabetic rats

The main purpose of this study is to evaluate the effect of intravenous irradiation of different low-level laser wavelengths on the activity of lecithin-cholesterol acyltransferase (LCAT), paraoxonase (PON1), catalase, and ferric reducing ability of plasma (FRAP) in diabetic rats. First, diabetes was induced in rats using streptozotocin (STZ). Enzymes' activity was measured in the blood samples and compared before and after intravenous laser blood irradiation. We used four continuous-wave lasers-IR (λ = 808 nm), Red (λ = 638 nm), Green (λ = 532 nm), and Blue (λ = 450 nm)-to compare the wavelength's effect on different enzymes' activity. Laser power was fixed at 0.01 mW and laser energy was changed by 2-, 4-, 6-, and 8-min time of radiations.The enzymes' activity of blood samples was measured 2, 6, and 24 h after radiation. The results show an increase in the activity of different enzymes when compare with diabetic non-radiated samples. More importantly, with a constant laser energy, the enzymes' activity increased with decreasing laser wavelength. It is important to note that with a constant laser energy, as the wavelength decreases, the photon energy increases and the number of photons decrease, while the enzyme's activity elevation increases. As a result, we can conclude that in intravenous low-level laser therapy, photon energy is more important than the number of photons even if their product, energy, is kept constant.

Effect of Low-Level Laser Irradiation on the Function of Glycated Catalase

Introduction: The aim of this work is to evaluate the effect of low-level laser irradiation (LLLI), by lasers with different wavelengths, on glycated catalase enzyme in vitro experimentally. Methods: This is done by measuring the activity and structure properties of glycated catalase enzyme. The structure properties were evaluated with circular dichroism (CD) and fluoroscopy methods. Three continuous wave (CW) lasers in the visible spectrum (λ =450, 530, 638 nm) and a 100-ns pulsed laser in the infrared spectrum (λ =905 nm) were chosen for comparison. For the infrared laser, same effects have been investigated for different energy doses. The effect of photon energy (hυ) at different wavelengths was measured on activity, CD, and fluoroscopy properties of catalase, and compared with the control group (samples without irradiation). The energy intensity of laser should not exceed 0.1 J/cm² . Experiments were performed on glycated catalase between 2 to 16 weeks after glycation of catalase. The LLLI effect was also investigated on the samples, by comparing the catalase activity, CD and fluoroscopy for different wavelengths. Results: Our results indicated, the decrease in catalase activity as a function of glycation time (weeks) for all samples, and a slight increase on its activity by different laser wavelengths irradiation for any fixed period of glycation time. Finally, the catalase activity has been increased as the laser's photon energy (hυ) intensified. More specifically, the blue laser (λ =450 nm) had the most and the red laser (λ =638 nm) had the least effect, and the green laser (λ =530 nm) had the medium effect on catalase activity as well. Furthermore, pulsed laser had an additional effect by increasing energy dosage. Conclusion: As we expected in all experiments, an increase in the catalase activity was coincident with a decrease in the catalase fluoroscopy and CD parameters.