The effect of photodynamic therapy on normal skeletal muscle in an animal model

Six sensitizers [haematoporphyrin derivative (HPD), Photofrin II, themeta-, ortho- andpara- isomers of the tetra(hydroxyphenyl)porphyrins (m-, o-, andp-THPP) and the potassium salt ofp-THPP (K-p-THPP)] were compared in their ability to sensitize mouse skeletal muscle and tumours. Muscle damage was measured as percentage weight increase due to oedema 4h after illumination and as percentage cross-sectional area necrosis at 48h. These results were compared with those that had previously been obtained for depth of necrosis in subcutaneous tumours. All the photosensitizers damaged both tumours and skeletal muscle. Acost (muscle damage) vsbenefit (subcutaneous tumour necrosis) analysis of the results showed thatm-THPP was the most tumour selective sensitizer of those studied. In the long-term, muscle healed by regeneration and some fibrosis with full return of function.     

The effect of photodynamic therapy by gold nanoparticles on Streptococcus mutans and biofilm formation: an in vitro study

Lasers in Medical Science - In this experimental study, we aimed to evaluate the antibacterial and anti-biofilm effects of photodynamic therapy with a photosensitizer in conjunction with Gold...     

Influence of pre-irradiation time employed in antimicrobial photodynamic therapy with diode laser

The aim of the present study was to evaluate, in vitro, the effect of different pre-irradiation times of the photosensitizer in photodynamic therapy in biofilms formed by Streptococcus mutans and Candida albicans, through the evaluation of the microbial load. The factors under study were as follows: times of pre-irradiation of the photosensitizer in three levels (1, 2, or 5 min). For the control of the cariogenic dental biofilm with antimicrobial photodynamic therapy (aPDT), methylene blue (0.01%) was used in association with the diode laser (InGaAlP) with a wavelength of 660 nm. Chlorhexidine digluconate (0.12% CHX) and saline were used as positive and negative controls, respectively. The study design was carried out in complete and randomized blocks. The sample consisted of 15 S. mutans biofilms cultures, randomly divided into five groups and 15 C. albicans cultures, also divided into five groups. The experiment was performed in triplicate (n = 3) and the response variables were obtained through quantitative analysis of bacterial viability, expressed in colony-forming units (CFU) per square millimeter of the specimen area. The data were analyzed with the aid of the ANOVA one-way test and Tukey’s post-test. All analyses were performed using the Graph Pad Prism 4.0 program, with a significance level of 5%. For the S. mutans group, only the saline solution presented a statistically significant difference when compared to the other treatments (p < 0.05), that is, the treatment with aPDT, irrespective of the irradiation time applied, was similar to the treatment with CHX and both were more effective in reducing cariogenic biofilm compared to saline. For the group of C. albicans, there was no statistical difference between the groups (p > 0.05). Therefore, it can be concluded that the treatment with aPDT reduced the number of CFUs of S. mutans in a similar way to CHX, independently of the pre-irradiation time applied. No effect of this therapy or of the different pre-irradiation times on the C. albicans biofilm could be observed. In this way, the pre-irradiation time of 1 min can be used to reduce the microbial load of S. mutans.     

Treatment of experimental periodontitis in rats using repeated adjunctive antimicrobial photodynamic therapy

The aim of this study was to histologically and histometrically evaluate the influence of repeated adjunctive antimicrobial photodynamic therapy (aPDT) on bone loss (BL) in furcation areas in rats. Periodontitis was induced by placing a ligature around the mandibular molar in 75 rats. The animals were divided into five groups: the SS group was treated with saline solution (SS); the SRP group received scaling and root planing (SRP); the aPDT1 group received SRP as well as toluidine blue (TBO) and low-level laser therapy (LLLT; InGaAlP, 660 nm; 4.94 J/cm²/point) postoperatively at 0 h; the aPDT2 group received SRP as well as TBO and LLLT postoperatively at 0, 24, 28, and 72 h; and the aPDT3 group received SRP, TBO, and LLLT postoperatively at 0, 48, 96, and 144 h. The area of BL in the furcation region of the molar was histometrically analyzed. Data were analyzed statistically (P?<?0.05). Animals treated with a single episode of aPDT showed less BL at days 7 and 30 than those who received only SRP treatment. No significant differences were found among the aPDT groups (P?>?0.05). Repeated aPDT did not improve BL reduction when compared to a single episode of aPDT.     

Effect of antimicrobial photodynamic therapy on periodontally infected tooth sockets in rats

Lasers in Medical Science - The aim of the present study was to evaluate the antimicrobial effect of antimicrobial photodynamic therapy (aPDT) in alveolar treatment of areas with induced...     

Effect of methylene blue-mediated antimicrobial photodynamic therapy on dentin caries microcosms

Antimicrobial photodynamic therapy (aPDT) has been proposed as an adjuvant treatment of dental caries, although there are no well-defined protocols to its clinical application. This study aimed to evaluate the influence of aPDT on the viability of microorganisms, vitality of biofilms, and lactic acid production of dentin caries microcosms. Biofilms were grown on bovine dentin discs in anaerobic conditions at 37 °C for 5 days, inoculating infected carious dentin in modified McBain medium plus 1% sucrose. The biofilms were treated by the combination of deionized water or 100 mg L^?1 methylene blue (MB) with 0, 37.5, or 75 J cm^?2 LED at 630 nm. The counts of total microorganisms, total streptococci, mutans streptococci, and total lactobacilli were determined by colony-forming units (CFU). The vitality of microbial cells in intact biofilms was measured by confocal laser scanning microscope (CLSM). The lactic acid production was analyzed by enzymatic spectrophotometry at 340 nm. Statistical analysis was conducted by Kruskal-Wallis and post hoc Dunn’s tests (P < 0.05). MB and 37.5 J cm^?2 LED alone did not interfere in the viability of microorganisms, unlike 75 J cm^?2 LED alone that decreased the total microorganism and lactobacillus counts. The combination of MB and 75 J cm^?2 LED reduced the viability of all microorganisms and the vitality of intact biofilms. The production of lactic acid was statistically lower in all treatment groups in comparison with that of the control (no treatment), except for MB alone. Therefore, the MB-mediated aPDT was effective in controlling the viability, vitality and the acidogenicity of dentin caries microcosms.     

Light dosimetry in brain tissue: an in vivo model applicable to photodynamic therapy

The intensity of blue-green (488 nm) and red (633 nm) light as a function of increasing distance from an implanted laser fiberoptic source in the brains of anesthetized rats was measured. There was significant (90%) attenuation of the light intensity for both 488 nm and 633 nm at a distance of 2.5 mm from the intracerebral laser light-emitting source. At greater distances from the light-emitting source that corresponded to areas in the cerebral cortex, there was greater attenuation of light intensity for increasing distance with 488 nm than with 633 nm because of the increased vascularity of the cortical mantle and absorption of 488 nm by hemoglobin. When hematoporphyrin derivative was given intravascularly, there was increased attenuation of 633 nm through the cerebral cortex that was similar to that seen for 488 nm in normals. Direct assessment of light intensity in living tissue, which we have shown is possible in this report, will aid in our understanding and interpretation of the histological changes that occur following photodynamic therapy.     

Rose bengal photodynamic antimicrobial therapy to inhibit Pseudomonas aeruginosa keratitis isolates

To evaluate the in vitro efficacy of rose bengal and riboflavin photodynamic antimicrobial therapy for inhibition the growth of four Pseudomonas aeruginosa (P. aeruginosa) isolates. Four different clinical P. aeruginosa isolates were collected from patients with confirmed keratitis. Each strain was mixed with either sterile water, 0.1% riboflavin solution, or 0.1% rose bengal solution to yield a final bacteria concentration of 1.5?×?10⁷ CFU/mL. Aliquots from each suspension were plated onto nutrient agar in triplicate. Plates were separated into two groups: (1) no irradiation and (2) 5.4 J/cm² of radiant exposure with custom-made LED irradiation sources. Separate irradiation sources were used for each photosensitizer. The riboflavin groups used a UV-A light source (375 nm) and rose bengal groups used a green light source (525 nm). Plates were photographed at 72 h and custom software measured bacterial growth inhibition. Growth inhibition to riboflavin and rose bengal PDAT showed strain-dependent variability. All four strains of P. aeruginosa showed greatest growth inhibition (89–99%) in the green irradiated-rose bengal group. The UV-A-irradiated riboflavin showed inhibition of 24–44%. UV-A irradiation only showed minimal inhibition (7–14%). There was little inhibitory effect in the non-irradiated photosensitizer groups. Rose bengal PDAT had the greatest inhibitory effect on all four P. aeruginosa isolates. In the UV-A-irradiated riboflavin group, there was moderate inhibition within the irradiation zone; however, there was no inhibition in the non-irradiated groups. These results suggest that rose bengal PDAT may be an effective alternative treatment for Pseudomonas aeruginosa infections.

     

The impact of photodynamic therapy on the viability of Streptococcus mutans in a planktonic culture

OBJECTIVE: This study investigated the effect of photodynamic therapy (PDT) with toluidine blue O (TBO) and a light-emitting diode (LED) on the viability of Streptococcus mutans cells in a planktonic culture. BACKGROUND DATA: Growth of Streptococcus mutans is the first step in the development of tooth decay. The use of light and dyes promotes cellular death in a noninvasive way, reducing treatment time. Methods: The LED used in this study had output power of 116 mW, its energy was 21 J, and the fluency was 2.18 J/cm(2). Samples were prepared and divided into five groups: (1) control group (-); (2) control group (+); (3) TBO; (4) LED; and (5) LED + TBO. RESULTS: One hundred percent of the bacteria were killed following irradiation with LED and TBO. The biofilm that formed on the glass surfaces was analyzed by SEM and colony count. CONCLUSIONS: It was demonstrated that PDT was efficient at killing microorganisms and preventing the formation of biofilms.     

Photodestruction of human dental plaque bacteria: enhancement of the photodynamic effect by photomechanical waves in an oral biofilm model

BACKGROUND AND OBJECTIVES: Periodontal disease results from the accumulation of subgingival bacterial biofilms on tooth surfaces. There is reduced susceptibility of these biofilms to antimicrobials for reasons that are not known. The goals of this study were to investigate the photodynamic effects of a conjugate between the photosensitizer (PS) chlorin(e6) (c(e6)) and a poly-L-lysine (pL) with five lysine residues on human dental plaque bacteria as well as on biofilms of the oral species Actinomyces naeslundii after their exposure to photomechanical waves (PW) generated by a laser in the presence of the conjugate. STUDY DESIGN/MATERIALS AND METHODS: Subgingival plaque samples from 12 patients with chronic destructive periodontitis were divided in 3 groups that were incubated for 5 minutes with 5 microM c(e6) equivalent from the pL-c(e6) conjugate in the presence of fresh medium (group I), PBS (group II), and 80% PBS/20% ethylenediaminetetra-acetic acid (EDTA) (group III) and were exposed to red light. Also, biofilms of A. naeslundii (formed on bovine enamel surfaces) were exposed to PW in the presence of 5 microM c(e6) equivalent from the pL-c(e6) conjugate and were then irradiated with red light. The penetration depth of the conjugate was measured by confocal scanning laser microscopy (CSLM). In both cases, after illumination serial dilutions were prepared and aliquots were spread over the surfaces of blood agar plates. Survival fractions were calculated by counting bacterial colonies. RESULTS: The PS/light combination achieved almost 90% killing of human dental plaque species. In biofilms of A. naeslundii, CSLM revealed that PW were sufficient to induce a 50% increase in the penetration depth of the pL-c(e6) conjugate into the biofilm. This enabled its destruction (99% killing) after photodynamic therapy (PDT). CONCLUSIONS: PW-assisted photodestruction of dental plaque may be a potentially powerful tool for treatment of chronic destructive periodontal disease.     

Monte Carlo simulations of photodynamic therapy in human blood model

Lasers in Medical Science - This study aims to simulate a therapeutic plan for a normal human blood model under various patho-physiological conditions, such as the development of leukemia/blood...     

Light dosimetry model for photodynamic therapy treatment planning

A light dosimetry model for photodynamic therapy is described leading to the dependence of necrosis depth on incident light dose. Semiempirical dosimetry relations are derived for four modes of light delivery. Results for Photofrin II at 630 nm are summarized in graphical form. Numerical values of the parameters and necrosis depth calculations are compared with literature data.     

大鼠膀胱癌模型的光动力学治疗

目的　验证采用新型光敏剂的光动力学治疗方法对于SD大鼠膀胱癌动物模型的有效性。方法　使用 0 .0 5 %N 丁基 N(4 羟丁基 )亚硝胺 (BBN)诱导成功的SD大鼠随机分为试验组2 0只和对照组 7只。实验组大鼠用剂量为 50mg/kg体重光敏剂溶液灌胃 ,2 4h后打开膀胱进行激光照射 ,能量为 50J/cm2 ,72h后取肿瘤标本送病理分析和DNA含量测定 ,对照组术前不灌药物。结果　光动力学治疗法 (PDT)治疗后试验组的肿瘤坏死发生率和面积均高于对照组 ,差异有显著性 (P <0 .0 5)。样本的平均DNA质量均数 :实验组 9.50 5pg,对照组 1 4 .2 69pg,差异有显著性 (P<0 .0 5)。结论　以CDHS80 1作为光敏剂的光动力学治疗对于SD大鼠膀胱癌模型是有效的     

Antimicrobial photodynamic therapy combined with conventional endodontic treatment to eliminate root canal biofilm infection

BACKGROUND AND OBJECTIVE: To compare the effectiveness of antimicrobial photodynamic therapy (PDT), standard endodontic treatment and the combined treatment to eliminate bacterial biofilms present in infected root canals. STUDY DESIGN/MATERIALS AND METHODS: Ten single-rooted freshly extracted human teeth were inoculated with stable bioluminescent Gram-negative bacteria, Proteus mirabilis and Pseudomonas aeruginosa to form 3-day biofilms in prepared root canals. Bioluminescence imaging was used to serially quantify bacterial burdens. PDT employed a conjugate between polyethylenimine and chlorin(e6) as the photosensitizer (PS) and 660-nm diode laser light delivered into the root canal via a 200-micro fiber, and this was compared and combined with standard endodontic treatment using mechanical debridement and antiseptic irrigation. RESULTS: Endodontic therapy alone reduced bacterial bioluminescence by 90% while PDT alone reduced bioluminescence by 95%. The combination reduced bioluminescence by >98%, and importantly the bacterial regrowth observed 24 hours after treatment was much less for the combination (P<0.0005) than for either single treatment. CONCLUSIONS: Bioluminescence imaging is an efficient way to monitor endodontic therapy. Antimicrobial PDT may have a role to play in optimized endodontic therapy.