An investigation of the cytotoxic and mutagenic potential of low intensity laser irradiation in Friend erythroleukaemia cells

Extracts of Trichocline sinuata (Asteraceae) as natural sensitizers in the photodynamic inactivation of Candida albicans

Despite significant progress in the development of phototherapy drugs, it is widely recognized that natural products remain the primary source of new photoactive compounds. Exploring uncharted flora in the east-central region of Argentina may offer a vast array of opportunities to isolate new photoactive molecules or plant extracts with high potential for use in antimicrobial photodynamic therapy (aPDT) against Candida albicans. To assess the photofungicidal potential of T. sinuata ("contrayerba") against C. albicans, the extracts underwent spectroscopic and chromatographic analysis, resulting in the identification of furanocoumarin metabolites with similar spectrophotometric properties in all extracts. The extract profiles were created using UHPLC-DAD, and seven furanocoumarins (FCs) were detected. The highest photoinactivation against C. albicans was observed for dicholormethanic extracts (MFC = 62.5 μg/mL), equal to xanthotoxin employed as a positive control. Furthermore, we determine that photochemical mechanisms dependent on oxygen (type I and type II processes) and mechanisms independent of oxygen (photoadduct formation) are involved in the death of these yeasts. These results support the use of native plants of the east-central region of Argentina as potent sensitizers for aPDT and suggest that they can replace xanthotoxin in treating superficial yeast infections of the skin.

ALA-PDT successfully treated multiple cSCC in situ and AK in a patient with Epidermodysplasia verruciformis

5-aminolaevulinic acid photodynamic therapy (ALA-PDT) has emerged as a non-invasive treatment modality for premalignant and malignant skin lesions. It has the advantage of better tolerance and providing better cosmetic outcomes than conventional treatment methods. Herein, we report a patient who suffered from multiple cutaneous squamous cell carcinoma (cSCC) in situ and actinic keratosis (AK) scattered in the body's sun-exposed areas, which had led him to undergo multiple surgical resections since the age of 16. Next-generation sequencing-based on a targeted gene capture panel revealed compound heterozygous mutations c.G559A and c.G1389A in the TMC8 gene. Combined with the typical clinical manifestations and mutation analysis, the patient was diagnosed with Epidermodysplasia verruciformis (EV). Due to the multiple AK and cSCC in situ lesions, ALA-PDT was applied. After 8 courses of ALA-PDT all lesions were successfully cleared without causing any scarring. Therefore, the use of ALA-PDT treatment may constitute a very promising and effective therapeutic modality for multiple cSCC in situ and AK secondary to EV.

Evaluation of lipolysis and toxicological parameters of low-level laser therapy at different wavelengths and doses in the abdominal subcutaneous tissue

Investigate the effects of low-level lasers therapy (LLLT) aiming abdominal lipolysis. Female Wistar rats received applications of LLLT directly in the abdominal skin twice a week (5 weeks). Except the control group (n = 5), animals received treatments with red wavelength 660 nm being (I) R3.3 group (n = 5): 3.3 J/cm², and (II) R5 group (n = 5): 5 J/cm², or infrared wavelength 808 nm being (III) IR3.3 group (n = 5): 3.3 J/cm², and (IV) IR5 group (n = 5): 5 J/cm². Abdominal subcutaneous and liver tissues were evaluated histologically. Levels of thiobarbituric acid reactive substances (TBARS) and catalase (CAT) activity were analyzed in liver tissue. In the peripheral blood aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides, and total cholesterol were investigated. Micronucleus assay was performed in the bone marrow. Except for the IR3.3 group, all treated groups reduced the body weight (p < 0.001). The R5 group reduced the abdominal subcutaneous tissue weight and thickness (p < 0.05), even though all treated groups reduced the number of adipocytes and its size (p < 0.001). No histological changes in the liver. There were no alterations in the triglycerides and LDL levels. The IR5 group increased the total cholesterol levels and decreased the HDL, ALT (both p < 0.05), and AST levels (p < 0.001). The group IR3.3 showed higher levels of ALP (p < 0.01). The R3.3 group increased the TBARS and CAT activity (p < 0.05). No mutagenic effects were found. The red laser treatment at 5 J/cm² led to lipolysis and did not alter the liver's parameters.

Reduction of Endotracheal Tube Biofilms Using Antimicrobial Photodynamic Therapy

BACKGROUND: Ventilator-associated pneumonia (VAP) is reported to occur in 12 to 25% of patients who require mechanical ventilation with a mortality rate of 24 to 71%. The endotracheal (ET) tube has long been recognized as a major factor in the development of VAP since biofilm harbored within the ET tube become dislodged during mechanical ventilation and have direct access to the lungs. The objective of this study was to demonstrate the safety and effectiveness of a non-invasive antimicrobial photodynamic therapy (aPDT) treatment method of eradicating antibiotic resistant biofilms from ET tubes in an in vitro model. METHODS: Antibiotic resistant polymicrobial biofilms of Pseudomonas aerugenosa and MRSA were grown in ET tubes and treated, under standard ventilator conditions, with a methylene blue (MB) photosensitizer and 664nm non-thermal activating light. Cultures of the lumen of the ET tube were obtained before and after light treatment to determine efficacy of biofilm reduction. RESULTS: The in vitro ET tube biofilm study demonstrated that aPDT reduced the ET tube polymicrobial biofilm by >99.9% (p<0.05%) after a single treatment. CONCLUSIONS: MB aPDT can effectively treat polymicrobial antibiotic resistant biofilms in an ET tube.

101 Hz frequency-modulated infrared light induces cytogenetic adaptive response in mouse bone marrow in vivo

The micronucleus test was used tu study the possibility of inducing cross-adaptive response in mouse bone marrow cells in vivo with an 850 nm infrared light modulated by a 101 Hz frequency, emitted by a light therapy device "Kurator". We demonstrated that this exposure led to a substantial reduction of cytogenetic cell damage produced by further exposure of animals to X-radiation in the dose of 1.5 Gy, i.e. it induced an adaptive response which did not differ by the magnitude and time course from the adaptive response to radiation.

Mitogenic potential inducible by He:Ne laser in human lymphocytes in vitro

The objective of the study was to investigate the mitogenic and genotoxic effects of He:Ne laser irradiation (632.8 nm) on human peripheral lymphocytes in vitro. We used the cytokinesis-block micronucleus assay, which incorporates cytochalasin B to inhibit cytokinesis while karyokinesis proceeds normally leading to the appearance of proliferating lymphocytes as binucleated cells. Also micronuclei will appear in cases of genotoxicologically-affected cells. Buffy coat leukocytes were exposed to 10 mW He:Ne laser at energy densities of 1, 2, 3 and 5 J/cm(2). Cells were then cultured in media 199 without any supplementation for 24, 48, 72 and 96 h adding cytochalasin B 24 h before harvesting of cells. Our results showed that laser-induced lymphocytes proliferate throughout the four consecutive days post-laser irradiation. The difference in the frequency of micronuclei between pre- and post-laser irradiation indicates that a He:Ne laser at such energy densities 1, 2, 3 and 5 J/cm(2) does not induce micronucleus formation. These results shed some light on the mechanism encountered by lymphocytes in the process of He:Ne laser-induced biostimulation.

Effect of low intensity monochromatic light therapy (890 nm) on a radiation-impaired, wound-healing model in murine skin

BACKGROUND AND OBJECTIVE

The use of low intensity laser and monochromatic light diodes as a therapeutic modality has become popular in a variety of clinical applications, including the promotion of wound repair. Despite this, the clinical evidence base for such application remains sparse; in contrast, recent studies have demonstrated a number of quantifiable photobiological effects associated with such therapy. In the present study, the effect of low intensity monochromatic light irradiation (MLI) at various radiant exposures upon a radiation-impaired wound model in murine skin was investigated.

STUDY DESIGN/MATERIALS AND METHODS

Male Balb/c mice (n = 50; age matched at 10 weeks) were randomly allocated to five experimental groups (n = 10 each group). In Group 1, mice were left untreated; in Groups 2-5, a well-defined area on the dorsum was exposed to 20 Gy X-ray irradiation. At 72 hours postirradiation, all mice were anaesthetised and a 7-mm-square area wound was made on the dorsum. All wounds were videotaped alongside a marker scale until closure was complete. In Groups 3-5, mice were treated with MLI (0.18, 0.54, and 1.45 J/cm2, respectively) three times weekly using a GaAlAs 890 nm multidiode (n = 60) array unit (270 Hz; maximum rated output, 300 mW; Anodyne, Denver, CO). Subsequently, the area of each wound was measured from video using an image analysis system (Fenestra 2.1), and results were analysed using repeated measure and one-factor ANOVA statistical tests.

RESULTS

X-ray irradiation caused a significant delay (P = 0.0122) in healing by day 7. MLI at 0.18 J/cm2 and 0.54 J/cm2 had no effect upon the rate of wound closure. However, a highly significant (P = 0.0001) inhibition occurred following MLI irradiation at 1.45 J/cm2 by day 16.

CONCLUSION

These findings provide little evidence of the putative stimulatory effects of monochromatic light irradiation in vivo, but, rather, reveal the potential for an inhibitory effect at higher radiant exposures.

Cell-cycle delay is induced in cells of a U937 promonocytic cell line by low-intensity light irradiation at 660 nm

Visible-light irradiation (VLI) at 660 nm and 11.5 J/cm2 inhibits proliferation of cells of the U937 promonocytic cell line, as monitored by autoradiographical analysis. The S-phase cell population is reduced at 6 h post-radiation treatment. Flow cytometric analysis confirms this, and also shows that light irradiation of cells induces a statistically significant increase in G2/M cells at 6 h post-radiation treatment. It has been postulated that VLI at 660 nm can alter cell-cycle progression by affecting intracellular concentrations of ions, in particular pH and calcium. However, no significant effects of light irradiation on these intracellular ions have been observed. These effects of VLI are not a consequence of radiation-induced DNA strand breaks, therefore events other than direct DNA damage are involved. These findings demonstrate a direct photobiological effect of VLI at 660 nm on the cell cycle, and indicate a previously unsuspected mechanism for the induction of cell-cycle delay that is neither a result of changes in the concentration of intracellular ions nor initiated by DNA strand breaks.

Laser therapy: a randomized, controlled trial of the effects of low-intensity Nd:YAG laser irradiation on musculoskeletal back pain

OBJECTIVE

To assess the effectiveness of low-intensity laser therapy in the treatment of musculoskeletal low back pain.

DESIGN

A double-masked, placebo-controlled, randomized clinical trial.

SETTING

A physical medicine and rehabilitation clinic.

PARTICIPANTS

Sixty-three ambulatory men and women between the ages of 18 and 70yrs with symptomatic nonradiating low back pain of more than 30 days' duration and normal neurologic examination results.

INTERVENTION

Subjects were bloc randomized into two groups with a computer-generated schedule. All underwent irradiation for 90 seconds at eight symmetric points along the lumbosacral spine three times a week for 4 weeks by a masked therapist. The sole difference between the groups was that the probes of a 1.06 microm neodymium:yttrium-aluminum-garnet laser emitted 542mW/cm2 for the treated subjects and were inactive for the control subjects.

MAIN OUTCOME MEASURES

Subject's perception of benefit, level of function as assessed by the Oswestry Disability Questionnaire, and lumbar mobility.

RESULTS

The treated group had a time-dependent improvement in two of the three outcome measures: perception of benefit and level of function. These results were most marked at the midpoint evaluation (p < .005, p < .01) and end of treatment (p < .017, p < .001) but tended to lessen at the 1-month follow-up (p < .10, p < .004). Lumbar mobility did not differ between the groups at any time. All tests were two-sample t tests with unequal variances.

CONCLUSIONS

Treatment with low-intensity 1.06 microm laser irradiation produced a moderate reduction in pain and improvement in function in patients with musculoskeletal low back pain. Benefits, however, were limited and decreased with time. Further research is warranted.