A Preliminary Investigation into the Effect of Low-Energy Lasers on Dental Pulp Stem Cell Proliferation and the Associated Mechanism.

BACKGROUND: Dental pulp stem cells (DPSCs) have self-renewal and multidirectional differentiation potentials. As such, DPSCs have a wide range of clinical applications. Low-level laser therapy (LLLT) has positive photobiostimulatory effects on cell proliferation, angiogenesis, osteogenic differentiation, bone regeneration, and fracture healing. However, there have been few studies on the effect of low-energy lasers on DPSC proliferation. METHODS: DPSCs were obtained from dental pulp tissue. The effects of LLLT on the proliferation of DPSCs and the associated mechanisms were investigated by in vitro culture and laser irradiation. RESULTS: LLLT with energy densities of 3.5 J/cm2 and 14 J/cm2promoted the proliferation of DPSCs. Differential protein expression studies suggested the stimulation of DPSC proliferation by LLLT involved the PI3K-Akt and Rap1 signaling pathways, as well as the apoptosis-related pathway. CONCLUSION: This preliminary study demonstrated that low-energy lasers have a pro-proliferative effect on DPSCs, and identified possible associated mechanisms. Our findings provide a theoretical basis for the clinical application of DPSCs and suggest novel strategies for the treatment of related diseases.

Biphasic dose response in the anti-inflammation experiment of PBM.

Non-invasive laser irradiation can induce photobiomodulation (PBM) effects in cells and tissues, which can help reduce inflammation and pain in several clinical scenarios. The purpose of this study is to review the current literature to verify whether PBM can produce dose effects in anti-inflammatory experiments by summarizing the clinical and experimental effects of different laser parameters of several diseases. The so-called Arndt-Schulz curve is often used to describe two-phase dose reactions, assuming small doses of therapeutic stimulation, medium doses of inhibition, and large doses of killing. In the past decade, more and more attention has been paid to the clinical application of PBM, especially in the field of anti-inflammation, because it represents a non-invasive strategy with few contraindications. Although there are different types of lasers available, their use is adjusted by different parameters. In general, the parameters involved are wavelength, energy density, power output, and radiation time. However, due to the biphasic effect, the scientific and medical communities remain puzzled by the ways in which the application of PBM must be modified depending on its clinical application. This article will discuss these parameter adjustments and will then also briefly introduce two controversial theories of the molecular and cellular mechanisms of PBM. A better understanding of the extent of dualistic dose response in low-intensity laser therapy is necessary to optimize clinical treatment. It also allows us to explore the most dependable mechanism for PBM use and, ultimately, standardize treatment for patients with various diseases.

Clinical effect observation of Nd: YAG laser combined with acyclovir in the treatment of herpes labialis / 口腔疾病防治

Objective@#To investigate the clinical efficacy of Nd: YAG laser combined with 3% acyclovir cream in the treatment of herpes labialis. @* Methods @# A total of 72 patients with herpes labialis were enrolled. According to the random number table method, the patients were divided into an observation group and a control group with 36 patients in the observation group and 36 patients in the control group. The Nd: YAG laser combined with 3% acyclovir cream was administered to the observation group, while 3% acyclovir cream was administered to the control group. The total effective rate, scab, scab removal, analgesic time, and quality of life were compared between the two groups.@*Results@# 7 days after treatment, the total effective rate of clinical treatment in the control group was 27 patients (75%), and that in the observation group was 34 patients (94.4%); the contrast difference was statistically significant (P < 0.05). Compared with those in the control group, the crusting, prolapse and analgesic time of the observation group were shorter, and the differences were statistically significant (P < 0.05). Compared with the control group, the observation group had higher quality of life scores, and there was a statistical significance (P < 0.05). @*Conclusion @#For patients with herpes labialis, using Nd: YAG laser combined with 3% acyclovir cream treatment can significantly improve the quality of life of patients and accelerate the speed of patient rehabilitation.

Development of a Minimally Invasive and Non-invasive Lipolysis Laser System for Effective Fat Reduction.

Introduction: Obesity is a global problem because it causes various complications. Methods for reducing fat for healthy life are being studied. In this study, we developed a minimally invasive and non-invasive lipolysis laser system for effective fat reduction. Methods: The laser had the wavelengths of 1980 nm and 2300 nm which have very good absorption of fat and water. We developed a minimally invasive laser system that breaks down fat by direct irradiation of fat tissue. This minimally invasive laser system uses a 808 nm diode laser and Nd:YVO4 to generate the 1064 nm wavelength, which is the pumping source of the nonlinear crystals. It is a mid-infrared lipolysis laser system having two wavelengths of 1980 nm and 2300 nm by controlling the temperature of nonlinear crystals. We also developed a non-invasive laser system that reduces fat with hyperthermia treatment by raising the temperature of adipocytes with a 1060 nm penetrating depth into the skin. In this non-invasive laser system, the In gallium arsenide (GaAs) diode laser is irradiated on the skin with an area of 4 × 8 cm2 through the hand-piece. The cooling system in the hand-piece protects the skin from burns. We studied the effectiveness and safety of each system through animal experiment. We studied the effects of lipolysis when these two systems were combined. Results: This research uses new wavelengths (1980 nm, 2300 nm) to increase the fat reduction effect with low energy (1.3 W). After using the 1060 nm (1.1 W/cm2) wavelength laser, when the 1980 nm and 2300 nm (1.3 W) laser were used, a lipolysis effect of about 35 % was obtained. Conclusion: We have developed a 1.3 W mid-infrared (1980 nm, 2300 nm) laser with good lipolysis effect with low power.

Effect of low le vel laser treatment combined with periodontal initial therapy on IL-8, b-FGF and IL-1βcontent in gingival crevicular fluid on peri-implantitis / 国际生物医学工程杂志

Objective To investigate the effect of low level laser treatment combined with periodontal therapy on interleukin-8 (IL-8), basic fibrobast growth factor (b-FGF) and interleukin-1β (IL-1β) level in gingival crevicular fluid on peri-implantitis , so as to evaluate the curative effect . Methods A total of 38 patients (50 implants) with early peri-implantitis were randomly divided into experimental group and control group, with 19 patients (25 implants) in each group. The patients in the experimental group were underwent level laser treatment combined with periodontal initial, and in the control group were only treated with periodontal initial. The implant gingival crevicular fluid was collected before the treatment (baseline), and 4 weeks and 12 weeks after the treatment. The levels of IL-8, b-FGF and IL-1βwere determined by enzyme-linked immunosorbent assay (ELISA). The SPSS19.0 software was used for the statistically analysis. Results The levels of IL-8, b-FGF and IL-1β of the experimental group and the control group were both improved at 4 weeks and 12 weeks after treatment comparing with that at the baseline, and the differences were statistically significant (all P<0.01). The differences in IL-8 and b-FGF levels in the gingival crevicular fluid were statistically significant at different time points for each group (all P<0.01). For the two groups, the differences in IL-1βwere not statistically significant at 4 weeks and 12 weeks after the treatment (all P>0.05). The levels of IL-8 and IL-1βof the experimental group were lower than those of the control group at 4 weeks after treatment, and the differences were statistically significant (all P<0.05). The level of b-FGF of the experimental group was higher than that of the control group at 12 weeks after the treatment, and the difference was statistically significant (P<0.05). Conclusions Low-energy laser can affect the level of cytokines in the gingival crevicular fluid on peri-implantitis. The combination of low level laser treatment and periodontal initial therapy is effective for treating peri-implantitis.

Photoacoustic Signal Enhancement: Towards Utilization of Low Energy Laser Diodes in Real-Time Photoacoustic Imaging.

In practice, photoacoustic (PA) waves generated with cost-effective and low-energy laser diodes, are weak and almost buried in noise. Reconstruction of an artifact-free PA image from noisy measurements requires an effective denoising technique. Averaging is widely used to increase the signal-to-noise ratio (SNR) of PA signals; however, it is time consuming and in the case of very low SNR signals, hundreds to thousands of data acquisition epochs are needed. In this study, we explored the feasibility of using an adaptive and time-efficient filtering method to improve the SNR of PA signals. Our results show that the proposed method increases the SNR of PA signals more efficiently and with much fewer acquisitions, compared to common averaging techniques. Consequently, PA imaging is conducted considerably faster.

Effect of low energy laser therapy on peri-implantitis in clinical patients / 国际生物医学工程杂志

Objective To study the effectiveness of basic therapy combined with low energy laser irradiation therapy to the patients with peri-implantitis, and to clarify the effect of laser irradiation in the treatment process. Methods A total of 38 patients (50 implants) who were diagnosed with early peri-implantitis from September 2017 to March 2018 in the Department of Stomatology, Tianjin First Central Hospital were randomly divided into the laser treatment group (n=25) and the conventional treatment group (n=25). The control group received basic treatment, and the laser treatment group received basic treatment combined with low energy laser irradiation (808 nm GaAlAs semiconductor continuous laser, average output power 80 mw, energy density 4 J/cm2, facula area 0.28 cm2, 15 seconds irradiation for each implant bag). The GIgingival index (GI), plaque index (PLI), sulcus bleeding index (SBI) and probe depth (PD) were examined before and 2 weeks and 8 weeks after the treatment. Results At 2 weeks and 8 weeks after the treatments, the indexes of the two groups were both improved compared with the baseline, and the differences were statistically significant (all P<0.05). Compared with the control group, the GI was significantly decreased (P=0.018) at 2 weeks after the treatment, and the GI, PD, and SBI were significantly decreased at 8 weeks after the treatment (P<0.001, P=0.018, and P<0.001, respectively). Conclusions At an energy density of 4 J/cm2, low energy laser irradiation at a wavelength of 808 nm can accelerate tissue healing of peri-implant inflammation after basic treatments.

[Use of laser for the prevention and treatment of oral mucositis induced by radiotherapy and chemotherapy for head and neck cancer]. / Utilización del láser para la prevención y el tratamiento de la mucositis oral inducida por quimioterapia y radioterapia de cabeza y cuello.

One of the complications of radiotherapy and chemotherapy is oral mucositis. Since the low energy laser is one of the most frequently recommended interventions by authors and international societies, the aim of this study is to review the scientific evidence on the use of lasers as a preventive and therapeutic in oral mucositis associated with treatment of cancer. We performed a literature search in PubMed and The Cochrane Collaboration Library, limiting the search to the last 20 years. We finally included 29 articles that contained 30 studies. Low energy laser phototherapy seems a promising intervention in both the prevention and treatment of oral mucositis associated with cancer treatment. Virtually all studies reviewed showed good results with no adverse effects and reductions in both incidence and severity of mucositis in all types of cancer treatments.

Low-level laser therapy versus ultrasound therapy in the treatment of subacromial impingement syndrome: a randomized clinical trial.

OBJECTIVE: The aim of this study was to compare the effectiveness of low-level laser therapy and ultrasound therapy in the treatment of subacromial impingement syndrome. MATERIALS AND METHODS: Thirty one patients with subacromial impingement syndrome were randomly assigned to low-level laser therapy group (n=16) and ultrasound therapy group (n=15). Study participants received 10 treatment sessions of low-level laser therapy or ultrasound therapy over a period of two-consecutive weeks (five days per week). Outcome measures (visual analogue pain scale, Shoulder Pain and Disability Index -SPADI-, patient's satisfactory level and sleep interference score) were assessed before treatment and at the 1st and 3rd months after treatment. All patients were analyzed by the intent-to-treat principle. RESULTS: Mean reduction in VAS pain, SPADI disability and sleep interference scores from baseline to after 1 month, and 3 months of treatment was statistically significant in both groups (P< 0.05). However, there was no significant difference in the mean change in VAS pain, SPADI disability and sleep interference scores between the two groups (P > 0.05). The mean level of patient satisfaction in group 1 at the first and third months after treatment was 72.45 ± 23.45 mm and 71.50 ± 16.54 mm, respectively. The mean level of patient satisfaction in group 2 at the first and third months after treatment was 70.38 ± 21.52 mm and 72.09 ± 13.42 mm, respectively. There was no significant difference in the mean level of patient satisfaction between the two groups (p > 0.05). CONCLUSIONS: The results suggest that efficacy of both treatments were comparable to each other in regarding reducing pain severity and functional disability in patients with subacromial impingement syndrome. Based on our findings, we conclude that low-level laser therapy may be considered as an effective alternative to ultrasound based therapy in patients with subacromial impingement syndrome especially ultrasound based therapy is contraindicated.

Spectrally Resolved Photoluminescence Imaging of ZnO Nanocrystals at Single-Particle Levels.

The intrinsic spectral line widths of defect-related transitions in quantum-confined semiconductor nanocrystals are often difficult to estimate using ensemble measurements because the extent of inhomogeneous broadening due to particle size distributions is not known precisely. To address this problem, we performed spectrally resolved photoluminescence (PL) microscopy of individual ZnO NC by directly populating the defects states using low-energy laser excitation. The temporal evolution of PL intensities shows discrete blinking behaviors, suggesting that the NCs are detected near single-particle levels. The transition energies of individual NCs are found to fluctuate around their mean position (2.25 eV) by ∼0.130 eV, which is attributed to particle size distribution and defects densities associated with each NC. The spectral line width associated with defect emission envelope of ZnO NCs is found to be inherently broad (200-400 meV), which further establishes the presence of multiple closely spaced defect energy levels within every ZnO NC.

Efecto del láser de baja energía sobre la expresión de GAP-43 (growth associated protein 43) en nervio isquiático lesionado de rata / Low-energy laser effect on expression of GAP-43 (growth associated protein 43) in rat isquiatic nerve injury

El láser infrarrojo se ha utilizado con fines terapéuticos en artritis reumatoide, dolor músculo-esquelético, enfermedades dentales y óseas. A nivel de lesiones nerviosas, se ha utilizado como coadyuvante en tratamientos conservadores y quirúrgicos; sin embargo, no está claro aún cual es su participación en los mecanismos moleculares asociados al proceso regenerativo. Varios genes y sus productos de expresión relacionados con regeneración axonal, están siendo investigados, entre éstos, la proteína GAP-43 (growth associated protein 43) ha sido detectada en diferentes tipos de lesiones de nervios periféricos, donde su expresión aumenta notablemente durante el proceso de recuperación. Con el propósito de evaluar la expresión del transcrito de GAP-43 en nervio isquiático de rata lesionado y, posteriormente, irradiados con láser infrarrojo de 2 J/cm2, se evaluó mediante RT- PCR en tiempo real la expresión del transcrito de GAP-43, en nervios lesionados tratados y no tratados. Los resultados indican que el nivel de expresión de GAP-43 en nervio tratado con láser de 2 J/cm2 , es mayor que en el nervio lesionado no tratado. También se observó un aumento de la expresión hasta dos semanas post-tratamiento. Estos resultados sugieren un efecto estimulante del láser infrarrojo de 2 J/cm2 sobre la expresión de GAP-43, en nervio isquiático de rata lesionado por compresión, lo cual podría estar relacionado con un menor tiempo de regeneración del nervio.

The Low-energy laser has been used in therapy for rheumatoid arthritis, musculoskeletal pain, dental disease and bone disease. At the level of nerve injury has been used as an adjunct to conservative and surgical treatments is not clear yet although the molecular mechanisms associated with the regenerative process. Several genes and their expression products associated with axonal regeneration are being investigated between these the protein GAP-43 (Growth associated protein 43) has been detected in different types of peripheral nerve injuries, where its expression increases markedly during the recovery process. In order to evaluate the expression of GAP-43 transcript in rat injured sciatic nerve and then irradiated with infrared laser of 2 J/cm2 was evaluated by RT-PCR in real time transcript expression of GAP-43 in nerve treated and untreated injuries. The results indicate that the expression level of GAP-43 in nerve treated with 2 J/cm2 laser is higher than in untreated injured nerve him. There was also an increased expression up to two weeks post-treatment. These results suggest a stimulatory effect of 2 J/cm2 infrared laser on the expression of GAP-43 in rat injured nerve compression, which could be related to a shorter time of regeneration of injured nerve.

The Effect of Low Energy Laser Irradiation on the Sciatic Nerve Regeneration of the Rat

OBJECTIVE: To verify the effect of low energy laser irradiation (LELI) on the regeneration of injured sciatic nerve of the rat by showing the functional improvement and the elevated immunoreactivities (IRs) of growth-associated protein 43 (GAP-43). METHOD: Twenty rats, which had standardized compression injuries to the sciatic nerves, received the calculated LELI therapy immediately after the nerve injury and four consecutive days. The functional status was evaluated by sciatic functional index (SFI), and GAP-43-IRs was evaluated by immunohistochemistry and RT-PCR. RESULTS: The SFI was recovered in LELI rats faster than in the control group. Although expression of GAP-43 in the injured sciatic nerve was increased both in the LELI and control groups, the intensities of GAP-43-IRs were much greater in LELI treated group at 1 and 3 weeks after nerve injury. Both SFI and GAP-43-IRs reached the same level at 5 weeks after the nerve injury. CONCLUSION: LELI enhanced the neural regeneration after experimentally induced sciatic nerve injury at the early stage of recovery. Considering the effect of LELI on nerve regeneration was not fully explained until now, this study could suggest the meaningful explanation on the mechanism of LELI effectiveness on neural regeneration.

The effect of intravascular low energy laser irradiation on renal function of patients with early diabetic nephropathy as revealed by the SPECT / 中华物理医学与康复杂志

Objective To investigate the effects of intravascular low energy laser irradiation on blood (ILIB) on renal function of the patients with early diabetic nephropathy. Methods Fifteen patients with type 2 diabetes mellitus complicated with early diabetic nephropathy, were treated with ILIB in addition to the conventional drugs, and observed the maximal time(Tmax)of renal concentration,the variation of 10 minutes residual rate and 15 minutes residual rate, respectively, by using the SPECT of isotone 99mTc-EC before and after ILIB treatment, and compared the results obtained before and after ILIB treatment. Results There were significant differences with regard to the 10 minutes residual rate (both the left and right kidney,P0.05). Conclusion ILIB could improve the excretion and secretion function of renal tubule in patients with the type 2 diabetes mellitus complicated with early diabetic nephropathy, and ILIB could be used as an effectively therapeutic method for patients with early diabetic nephropathy.

Therapeutic Effects of Low Energy Laser on Acute Phase of Herpes Zoster / 대한피부과학회지

BACKGROUND: Herpes zoster(HZ), caused by reactivation of latent varicella-zoster virus, is manifested by dermatomal distribution of skin rashes, acute pain and post-herpetic neuralgia by pathologic involvement of the sensory ganglia. Low-energy laser(LEL) deliver a small amount of energy without elevation of the tissue temperature. LEL is reported to have various biologic effects such as anti-inflammatory, analgesic, regenerative, antiallergic, immunocorrective, and antibacterial effects. OBJECTIVE: We attempted to evaluate the therapeutic effect of LEL on an acute phase of HZ. METHODS: A total of 60 patients with acute HZ were enrolled in the study. The control group(30 patients) received medications including analgesics, antihistamine, and topical care without LEL irradiation. The experimental group(30 patients) were irradiated with LEL daily for 7 days in addition to the same kinds of medications for the control group. The efficacy of LEL irradiation for HZ was assessed by analyzing changes in skin rashes, pain scores, and postherpetic neuralgia.