Journal of Lasers in Medical Sciences
Volume:11 Issue: 4, Autumn 2020

This study aimed to perform a systematic review of the literature followed by a meta-analysis about the efficacy of sonodynamic antimicrobial chemotherapy (SACT) in bacterial infections.

According to the PICOS (population, intervention, comparison and outcome) recommendations and PRISMA guidelines, an electronic search was conducted in PubMed, SCOPUS, Embase, and Cochrane Library based on the MeSH terms. All analyses were conducted using Biostat’s Comprehensive Meta-Analysis version 2.0. The inter-study heterogeneity and publication bias assessments were carried out on the studies using I2 and the Egger’s regression test.

Initially, 126 articles were identified in the electronic search, and 14 studies remained after analysis and exclusion of the duplicated studies and eligibility criteria. All results from the included studies displayed a significant reduction of microorganisms. The meta-analysis demonstrated a significant reduction in the bacterial load in all analyses (0.944% [95% CI, 0.901-0.969%; P=0.000]). Also, there was a low risk of bias for microbial load reduction without the evidence of publication bias.

The results highlight that there is scientific evidence emphasizing the effectiveness of SACT in reducing the count of microorganisms in bacterial infections

Currently, a laser is a popular technology in urological surgeries. The important laser-related issue is the time when a surgeon reaches an acceptable level of safety and efficacy using laser technology.

In this review, we aimed to assess the learning curves of three types of surgeries in urology, including photoselective vaporization of the prostate (PVP), holmium laser enucleation of the prostate (HoLEP) and retrograde intra-renal surgeries (RIRSs). Here, we searched Medline, Web of Science, Google Scholar, EMBASE, and Scopus for such keywords as Urology, laser, laser vaporization, prostate, nephrolithiasis, benign prostatic hyperplasia (BPH), and learning curve.

We evaluated 14 studies about PVP, 17 about RIRS, and 29 studies about HoLEP. Also, we separately discussed the learning curves of these three kinds of surgeries in detail.

All the urologists, even expert surgeons, should attend a formal training course and have a skilled tutor present at their first cases

Alzheimer disease (AD) is characterized by the decline of cognitive functions such as learning and memory. Scientific society has proposed some non-pharmacological interventions, among which photobiomodulation has gained prominence for its beneficial effects. Therefore, we investigated, through systematic review, the therapeutic potential of photobiomodulation in AD.

This systematic review was registered under the number CRD42019128416 in the International Prospective Record of Systematic Reviews (PROSPERO). A systematic search was conducted on the bibliographic databases (PubMed and ScienceDirect) with the keywords based on MeSH terms: “photobiomodulation therapy” or “low-level laser therapy” or “LLLT” or “light emitting diode” and “amyloid” or “Alzheimer”. The data search was conducted from 2008 to 2019. We follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. The search strategy included experimental in vivo and in vitro studies in the English language and photobiomodulation as a non-pharmacological intervention. We included 10 studies, being 5 in vivo studies, 4 in vitro studies and 1 study using in vivo and in vitro. To evaluate the quality of the studies, we used the Rob tool of the Systematic Review Center for Laboratory Animal Experimentation (SYRLE).

The studies showed that photobiomodulation is able to reduce inflammatory response, oxidative stress and apoptotic effects generated by amyloid beta (Aβ) and restore mitochondrial function and cognitive behavior.

Taken together, these results indicate that photobiomodulation may be a useful tool for treating AD

Currently, the COVID-19 pandemic is an important health challenge worldwide. Due to the cytokine storm, the mortality rate in acute respiratory distress syndrome (ARDS) is high, but until now no therapy for these patients was approved. The aim of this review was to discuss the possible anti-inflammatory effect of photobiomodulation therapy (PBMT) on ARSD patients and present the potential role of low-level laser therapy (LLLT) in the improvement of respiratory symptoms associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Studies about PBMT in inflammation and ARSD patients were examined. A primary search with reviewing English-language citations between 2005 and 2020 using the keywords COVID-19, ADRS, cytokine storm, low-level laser therapy, anti-inflammatory, and photobiomodulation was performed. The initial search yielded 818 articles; however, 60 articles were selected and discussed in the present study.

The results of the selected studies showed the usefulness of PBMT in the treatment of inflammation and ARSD in patients with COVID-19 infection. This therapy is non-invasive and safe to modulate the immune responses in ARSD patients.

PBMT can potentially reduce the viral load and bacterial super-infections in patients with COVID-19 infection and control the inflammatory response. Therefore, the use of PBMT could be an efficient strategy for preventing severe and critical illness in SARS-COV2 infection

Although the application of ultraviolet B (UVB) in phototherapy of human skin is a common therapeutic method, it is known as a risk factor for skin cancer. This study aims to assess the role of differentially expressed genes (DEGs) to find the critical one that is mainly responsible for skin protection against UVB radiation.

The gene expression profiles of irradiated mice by UVB that issued skin protection against exposure are extracted from Gene Expression Omnibus (GEO) and analyzed by GEO2R. The significant DEGs are assessed via gene ontology (GO) analysis and the critical individuals are investigated via action mapping.

Thirty-eight significant DEGs that provide skin resistance against UVB irradiation were determined. Among the query DEGs, 26 individuals were related to 43 biological terms. Flt4, F3, Tspan6, Cblb, and Itgb6 were highlighted as the critical DEGs to promote skin protection against UVB irradiation.

The finding indicates that Flt4 is the key DEG that is mainly responsible for protecting skin from UVB exposure

This study was performed to compare the effects of single and multiple irradiations of low-level laser therapy (LLLT) on bone regeneration in a mid-palatal suture following rapid palatal expansion (RPE).

In this animal study, 40 male Wistar rats underwent RPE for 7 days and were divided into 4 groups including A: single LLLT on day 7, B: Multiple LLLT on days 7, 9, 11, 13 and 15, C: control (no LLLT), and D: sacrificed on day 7. Animals in group D were used to determine the amount of suture expansion. LLLT was done by a diode laser set at an 808 nm wavelength with a useful power output of 100 mW and duration of 0.1 ms. LLLT was applied to three points. After three weeks of retention, the rats were sacrificed and beheaded and the maxilla was evaluated by occlusal radiography, μ-CT, and histomorphometric analyses. A comparison of the mean measurements between the groups was performed using ANOVA and the Tukey post hoc test.

Based on occlusal radiography and μCT, bone density in group B was significantly higher than group A and group C (P< 0.05). There was no significant difference in bone density between group A and group C (P> 0.05). Mean suture width (MSW) in group B was significantly lesser than the control group (P= 0.027) while there was no significant difference between MSWnin groups A and B (P= 0.116) and groups A and C (P = 0.317).

It may be concluded that multiple low-power laser irradiation improves bone regeneration after RPE while single irradiation does not have a positive effect

Introduction:

 Varicosis is a condition affecting the superficial venous system of the lower limbs. Endovenous laser ablation (EVLA) is a minimally invasive method that uses different frequencies of laser for treatment. Radiofrequency (RF) has also been effectively used for vein ablation through thermal mechanisms. This study compares the success rate and side effects of EVLA and RF to treat varicose veins in the lower limbs within 12 months.

In this two-arm, parallel-group, randomized controlled, single-blind study, 1090 patients with lower limb varicosis proven by Doppler ultrasonography (DUS) were randomly placed into one of the two groups: EVLA and RF ablation. In the EVLA group, we used a 980-nm diode laser in a pulse mode and in the RF group, a 7-cm ClosureFast (Covidien, USA) catheter with an RF generator. We assessed pain during the operation and 8 and 24 hours after the surgery by the numerical rating scale (NRS). The patients were followed up on day 7, then 3, 6, and 12 months postoperatively. The presence or absence of pain and then the severity of pain (according to NRS), the recurrence rate, complications, and the length of the procedure were compared.

There was no significant difference between the two groups in the patients’ characteristics, major adverse events and pain severity during the procedure and 8 and 24 hours after the surgery. According to NRS, the mean chronic pain severity in the EVLA group was 3.99± 0.754 versus 4.50± 0.657 in the RF group, and the difference was not significant. The length of operation and the recurrence rate 12 months after the procedure were not significantly different.

The results of our study further establish the efficacy of EVLT and RF ablation for lower limb varicosis treatment without any significant difference in the clinical outcomes and complications during a 12-months follow-up

Antimicrobial photodynamic therapy (aPDT) as a supplement to the conventional root canal preparation has shown promising results. Previous studies have adopted various combinations of light sources and photosensitizers, which makes it difficult to compare the disinfection efficacy of different PDT protocols. The aim of the present study was to compare the efficacy of three photosensitizers (toluidine blue, methylene blue, and curcumin) in PDT using LED against Enterococcus faecalis in root canal disinfection.

Root canals of 54 single-rooted extracted teeth were prepared using the ProTaper Gold rotary system and were incubated with E. faecalis for three weeks. They were then randomly divided into five experimental groups and a control group: (1) Irrigation with 2.5% NaOCl for 30 seconds, (2) NaOCl irrigation followed by TB-PDT, (3) NaOCl irrigation followed by MB-PDT, (4) NaOCL irrigation followed by curcumin-PDT, (5) Curcumin solvent (1% ethanol+1% BSA), (6) Control (irrigation with normal saline). Sampling was done by collecting dentin shavings from the root canals, and colony-forming units were determined for each treatment group. The data were analyzed by Kruskal-Wallis and Mann-Whitney U tests. The significance level was set at P˂0.05.

In all treatment groups, the mean values of colony forming unit (CFU) decreased by 99% compared to the control group. The lowest mean values of CFU were observed in groups 2 and 4, followed groups 3, 1, and 5 respectively. The mean CFU count in group 2 was significantly lower than that of group 1 (P value=0.011), while there were no significant differences among groups 1, 3, and 4 (P value >0.05).

The adjunction of toluidine blue-mediated PDT by means of a light-emitting diode to NaOCl irrigation increased its antibacterial efficacy against E. faecalis and could be an effective complementary method in root canal disinfection

Introduction:

 Low-level laser therapy (LLLT) is accompanied by protein expression change in the body. There are many efforts to find a clear relationship between the differentially expressed proteins. This study aims to find the central differentiated expressed proteins of plasma after LLLT.

Six proteins are extracted from a proteomics study and the network including these query proteins plus 100 first neighbors was constructed. The central proteins were determined based on degree value, betweenness centrality, closeness centrality (CC), and stress (The centrality parameters).

Among 106 nodes of the network, 10 proteins were characterized with the most values of degree, betweenness centrality, CC, and stress. These proteins were determined as central proteins in response to LLLT in plasma.

Three query proteins, AHSG, FGG, and SERPINA1, plus 7 first neighbors, namely FGA, ALB, KNG1, FN1, APP, TIMP1, and F5, were identified as central proteins which were dysregulated.

Due to the complications of root canal treatment, conservative modalities to preserve pulp vitality are favorable. Direct pulp capping (DPC) refers to the coverage of the pulp tissue exposed by a biocompatible agent that can improve the prognosis of the tooth by 44% to 95%. Some recent studies have reported more predictable results (a success rate of about 90%) for DPC with laser and regenerative materials such as mineral trioxide aggregate (MTA). This study aimed to clinically compare DPC with ProRoot MTA alone and in combination with Er:YAG (erbium-doped yttrium aluminium garnet) laser irradiation (2940 nm).

This clinical trial was conducted on 26 patients with a mean age of 29 years (in the range of 17 to 46 years) who required DPC following pulp exposure during deep caries removal. The teeth were divided into two groups. In the control group, the teeth underwent DPC with ProRoot MTA while in the test group, the teeth were first irradiated with a 2940 nm Er:YAG laser and then underwent DPC with ProRoot MTA. The patients were recalled at one, 3 and 6 months for the follow-up (clinical and radiographic examinations). The data were analyzed using Fisher exact test.

The success rate was 75% in the laser group and 93% in the control group. The groups were not significantly different (P>0.05).

No significant difference was found in terms of the success rate of DPC with ProRoot MTA alone and in combination with Er:YAG laser irradiation.

This randomized clinical trial was designed to investigate the effect of carbon dioxide laser on the treatment of minor recurrent aphthous stomatitis (miRAS) as a painful and common oral ulcer.

Fifteen patients with miRAS entered into this study after compliance with the inclusion and exclusion criteria. The patients were assigned to three groups of pulsed CO2 laser, continuous CO2 laser, and control. A pulsed CO2 laser with power of 261 W and pulse duration of 180 microseconds and continuous CO2 lasers with the power of 1 W and radiation duration of 5-10 seconds were used. In the control group, topical triamcinolone ointment of 0.1% was used. The degree of pain was measured using the visual analogue scale (VAS). The patients were evaluated in terms of pain intensity before and immediately after the treatment and at follow-up hours, 12, 24, 48, and 72 hours after the intervention, and changes in the size of the ulcers were measured before the treatment and on third, fifth, and seventh days.

The effect of CO2 laser with pulsed and continuous radiation on the pain intensity of aphthous lesions, immediately after the treatment and at subsequent follow-up hours were similar and even better than the control group (P<0.05). All three treatments had a similar effect on the size of the ulcer, which was not statistically significant (P>0.05).

The results of this randomized controlled trial (RCT) showed that the carbon dioxide laser, whether with pulsed radiation or continuous radiation compared to the control group, had a better impact on the pain relief of aphthous lesions.

Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment. Various treatments have been suggested for CTS and there is no consensus on their superiority and the order of their use. Laser therapy is a non-invasive treatment method for many musculoskeletal diseases, including CTS. This study aimed to determine and compare the effect of high-power lasers (HPLs) and low-power lasers (LPLs) on pain severity, function, pinch strength, and nerve conduction study findings in patients aged 30-50 years with mild or moderate CTS.

This is a prospective, randomized, single-blind clinical trial. The study population included 45 patients aged 30-50 years who came to the physical medicine and rehabilitation clinic of Shohada-e-Tajrish hospital and mild or moderate CTS was confirmed for them. Patients were randomly assigned to control, LPL therapy, and HPL therapy groups. Pain, function, pinch strength, and nerve conduction study findings were recorded in all groups before, immediately and 12 weeks after the treatment. All data were compared using SPSS version 21.

All groups showed improvement regarding pain, function, and pinch strength. Laser therapy showed significantly better results compared to a wrist splint, but no significant difference was seen between high-power and LPL therapy groups. Nerve conduction evaluation findings did not reveal any significant difference.

Both the wrist splint and laser therapy can improve the symptoms of carpal tunnel syndrome. HPL therapy showed better results, although not significantly different from LPL therapy

Gamma radiation is accompanied by prominent biological effects and damages. Cell proliferation and tumorigenesis are highlighted as the main resulted effects of gamma radiation on cultured cells. This study aims to assess the dysregulated mode of gene function after gamma radiation in human Jurkat cells.

Six gene expression profiles from Gene Expression Omnibus (GEO) were analyzed by GEO2R to find the significant differentially expressed genes (DEGs) via gamma radiation. Action map analysis was applied to screen the query DEGs.

Among 108 study genes, 20 critical DEGs including AURKA, AURKB, BORA, CCNB1, CCNB2, CCNF, CDC20, CDCA8, CENPA, CENPE, CENPF, KIF18A, KIF20A, KIF23, BUB1, DLGAP5, ECT2, PLK1, SGO2, and TPX2 were introduced as down-regulated genes by the gamma ray.

Activators of the introduced critical genes may be the cell protector against gamma radiation.

Introduction:

 Cervical cancer is recognized as one of the major causes of mortality among elderly women. Although there are several different therapeutic worldwide guidelines, many researchers have focused on screening new methodologies and technologies to elevate the efficiency of cervical cancer treatment. The simultaneous use of photodynamic therapy (PDT) along with chemotherapy as cisplatin has achieved good aims in the treatment of cervical cancer.

A2780 cells were treated with cisplatin, photodynamic progress (laser with methylene blue as a photosensitizer compound) and a combination of cisplatin and PDT. The lithic effect of the laser, methylene blue and their combination and the IC50 value of cisplatin were calculated for each group. The amount of malondialdehyde (MDA) as membrane lipid peroxidation product and released lactate dehydrogenase was measured in the medium. The toxicity of each agent was evaluated by the MTT technique.

The results show that a combination of PDT and chemotherapeutic agent cisplatin caused a twofold decrease in viable cervical cancer cells compared to each therapeutic progress. The combination of both laser therapy and cisplatin enhanced cancer cell membrane disruption by increased membrane lipid peroxidation and apoptotic enzyme activation by the elevation of lactate dehydrogenase activity.

The results indicated that cisplatin combined with PDT had a greater therapeutic effect on A2780 as a cervical cancer cell line. Therefore, PDT in combination with chemotherapy enhances the effectiveness of chemotherapeutic agents by the disruption of the cancer cell membrane and switching the apoptosis progress with less adverse effects.

Imaging technologies have been developed to assist physicians and dentists in detecting various diseases. Photoacoustic imaging (PAI) is a new technique that shows great applicability to soft tissues. This study aimed to investigate the effect of diode laser intensity modulation on photoacoustic (PA) image quality.

The prototype of the PAI system in this study utilized a non-ionizing 532 nm continuous-wave (CW) diode laser illumination. Samples in this study were oral soft tissues of Sprague–Dawley rats fixed in 10% formalin solution. PA images were taken ex vivo by using the PAI system. The laser exposure for oral soft tissue imaging was set in various duty cycles (16%, 24%, 31%, 39%, and 47%). The samples were embedded in paraffin, and PA images were taken from the paraffin-embedded tissue blocks in a similar method by using duty cycles of 40%, 45%, 50%, 55%, 60% respectively to reveal the influence of the laser duty cycle on PA image quality.

The oral soft tissue is clearly shown as a yellow to red area in PA images, whereas the non-biological material appears as a blue background. The color of the PA image is determined by the PA intensity. Hence, the PA intensity of oral soft tissue was generally higher than that of the non-biological material around it. The Kruskal–Wallis test followed by Mann–Whitney post-hoc analysis revealed significant differences (P< 0.05) in the quality of PA images produced by using a 16%–47% duty cycle of laser intensity modulation for direct imaging of oral soft tissue fixed in 10% formalin solution. The PA image quality of paraffin-embedded tissue was higher than that of direct oral soft tissue images, but no significant differences in PA image quality were found between the groups.

The PAI system built in this study can image oral soft tissue. The sample preparation and the diode laser intensity modulation may influence the PA image quality for oral soft tissue imaging. Nonetheless, the influence of diode laser intensity modulation is not significant for the PA image quality of paraffin-embedded tissue

Genomics and bioinformatics are useful methods for exploring unclear aspects of radiation effects on biological systems. Many radiation-induced alterations in irradiated samples are post-radiation time-dependent. This study aims to evaluate the post-irradiation effects of the gamma ray on human Jurkat cells.

Gene expression profiles of the samples harvested 6 and 24 hours after radiation to find the critical differential expressed genes and the related pathways. Samples are provided from Gene Expression Omnibus (GEO) and analyzed by ClueGO.

Twnety-nine critical genes were determined as the important affected genes and 7 classes of related pathways were introduced. CCNE2, PSMD11, CDC25C, ANAPC1, PLK1, AURKA, and CCNB1 that were associated with more than 6 pathways were related to one of the determined pathway groups.

Cell protecting pathways were associated with the genes (HSPA5, HSPA8, HSP90B1, HMMR, CEBPB, RXRA, and PSMD11) which were related to the minimum numbers of pathways. The finding of this study corresponds to repair processes which depend on post-radiation time. It seems these sets of genes are suitable candidates for further investigation

Photodynamic therapy (PDT) is a process that uses a light source (e.g. laser), oxygen molecules and a photosensitizing agent. PDT aims to act against pathogens, including those resistant to antimicrobials. The association of PDT with natural drugs, such as Propolis, has not been widely studied.

Therefore, this study aimed to evaluate the antimicrobial effect of PDT in vitro by using Propolis as a photosensitizing agent. For this purpose, the dry Propolis extract was used as a photosensitizer and a low-power laser (Photon Laser III model) was irradiated onto the microwells for 90 seconds. Gram-positive and Gram-negative bacterial strains were used in the tests at a concentration of 5 × 105 CFU/mL. Initially, the antibacterial activity of the photosensitizers without laser action was determined by using a serial microdilution method before the experiment with a laser. After the incubation of the plates in a bacteriological oven, resazurin (0.1%) was added and the minimum inhibitory concentration (MIC) was determined. Alterations in the morphology of the bacteria were analysed by using atomic force microscopy (AFM).

Bacteria were sensitive to Propolis with MICs ranging from 13.75 to 0.85 mg/mL, but no susceptibility was observed for methylene blue without laser application. A change was observed for MIC values of Propolis against Staphylococcus aureus after irradiation, which decreased from 1.71 mg/mL to 0.85 mg/mL. However, this behaviour was not observed in Escherichia coli, the only gram-negative strain used. In addition, AFM images revealed alterations in the size of one of the bacteria tested.

The Propolis is more active against gram-positive bacteria and PDT improved its activity against one of the strains tested

Inferior alveolar nerve (IAN) injury is a serious complication during intraoral surgeries. We aimed to evaluate the outcome of photobiomodulation (PBM) therapy in patients with IAN injury associated with third molar or implant procedures.

Eight patients with an alteration of sensory function of the IAN after third molar or implant surgeries were enrolled in this case series study. The patients received 10 sessions of PBM therapy (810 nm diode laser, 200 mW, 10 J/cm2 per point, three times a week). Pinprick (PP) and visual analogue scale (VAS) neurosensory tests were recorded at each treatment session and 14 days after the last treatment. The association between explanatory variables and the outcome of interest was analyzed using generalized estimating equations.

The median percentage change of outcomes from the first to the last visit was as follows: VAS score: +125.00% (range: 50.00 to 166.67); PP score: +350% (range: 150 to 800). The duration of paresthesia was inversely correlated with changes in VAS and PP scores. No significant association was found between patients’ gender or age and changes in VAS and PP scores.

Considering the limitations of this study, PBM with the parameters used in this study presented positive effects on neurosensory recovery in patients suffering from IAN injury associated with routine intraoral procedures. Patients with shorter duration of paresthesia tended to respond more favorably to PBM therapy.