光化学作用对肿瘤细胞胞吞大分子的释放

目的观察不同光敏剂在肿瘤细胞内的分布,以及光化学作用对肿瘤细胞胞吞大分子的释放作用.方法使用激光共聚焦显微镜观察ALA、ALA-HE、HMME、TPPSa2在肿瘤细胞SW480、K562的胞内分布,使用FITC-右旋糖酐观察肿瘤细胞对荧光标记大分子的胞吞作用,通过光照激发光敏化细胞,动态观察光化学作用前后胞吞大分子FITC-右旋糖酐的胞内分布变化.结果ALA、ALA-HE、HMME、TPPSa24种光敏剂均表现为胞质分布,核内分布少.ALA、ALA-HE的胞内分布主要表现为胞质内的弥散性荧光.HMME则表现为胞质内颗粒状荧光与弥散荧光同时存在.TPPSa2为典型的胞质内颗粒状荧光分布.光敏剂在SW480、K562两种肿瘤细胞的胞内分布没有明显差异.光照激发不同光敏剂对肿瘤细胞胞吞FITC-左旋糖酐的胞内分布影响不同.由TPPSa2及HMME活化而产生的光化学作用表现出明显的荧光颗粒重分布,ALA、ALA-HE则对胞吞荧光无明显重分布作用.结论不同光敏剂因其不同的理化性质而表现为不同的胞内分布.光化学作用可对肿瘤细胞胞吞大分子产生胞吞释放作用,其作用机制可能与光化学作用对胞吞泡的破坏有关.     

Localizing and photosensitizing mechanism by tetra(3-hydroxyphenyl)porphin in vivo on human malignant melanoma xenografts in athymic nude mice

Observations on time-dependent localization of tetra(3-hydroxyphenyl)porphin (3-THPP) in human malignant melanoma transplanted to athymic nude mice from 1 to 120 h after intraperitoneal (i.p.) 10 mg kg^–1 b.w. administration were made by means of fluorescence microscopy. Fluorescence was found on the membrane of the melanoma cells and in the cytoplasm with a peak fluorescence intensity at 24 h post-injection of 3-THPP. The growth of the tumour cells was obviously inhibited at an early stage after PCT. Morphological changes of the tumour at various intervals after treatment by PCT with 3-THPP were also observed. Diffuse degeneration of the tumour cells with swelling of mitochondria and endoplasmic reticulum, heterochromatin aggregation and margination, etc., and subsequently diffuse necrosis with little or no the background of tumorous vascular response were found at an early stage after PCT. On the other hand, it was also observed that the necrosis of the melanoma areas was caused as a consequence of tumorous vascular injury at a later stage after PCT. Thus, two tumoricidal processes caused by PCT with 3-THPP were seen: a direct phototoxic action on tumour cells at an early stage after PCT and an indirect effect secondary to tumorous vascular injury at a later period after PCT.     

Evaluation of antimicrobial activity of association of chlorhexidine to photosensitizer used in photodynamic therapy in root canals infected by Enterococcus faecalis

IntroductionThe aim of the present study was to evaluate, in vitro, the influence of the addition of chlorhexidine to photosensitiser in the antimicrobial activity of photodynamic therapy in root canals infected by Enterococcus faecalis.MethodsThe root canals of 50 single-rooted human extracted teeth were enlarged up to a file F3 of Pro-Taper system, autoclaved, inoculated with Enterococcus faecalis and incubated for 14 days. The samples were divided into five groups (n = 10) according to the protocol of decontamination: G1 (control group) − no procedure was performed; G2–photosensitiser (0.01% methylene blue); G3–2% chlorhexidine gel; G4–photodynamic therapy; and G5–photodynamic therapy with photosensitiser modified by chlorhexidine. Microbiological test (CFU counting) was performed to evaluate the effectiveness of proposed treatments. Data were subjected to one-way ANOVA followed by post-hoc Tukey test (α=0.05).ResultsGroup 3 (CHX) showed the lowest mean contamination (2.03 log₁₀ CFU/mL), being statistically different from all other all groups (p < 0.05). There was no statistically significant difference between groups 4 (PDT) and 5 (PDT + CHX) (p < 0.05), being more effectives against E. faecalis when compared to groups 1 (NT) and 2 (MB), and less effective when compared to group 2 (CHX).ConclusionsThe addition of chlorhexidine to photosensitiser did not result in a better decontamination potential of photodynamic therapy alone over root canals infected by E. faecalis.     

声敏剂与光敏剂的研究进展

本文概述了声动力疗法与光动力疗法的基本原理及常用声敏剂与光敏剂的发展状况,并对声敏剂与光敏剂的发展进行展望.     

Photoactivated disinfection of Streptococcus intermedius through dentin disc at clinically relevant intervals: An in vitro study

In this present study we have tested the impact of porfimer sodium (Photofrin^®, AXCAN PHARMA Inc., Quebec, Canada) photoactivated disinfection (PD) on cells of Streptococcus intermedius in suspension. In order to provide basic data to support future clinical studies of PD in dentistry the study used exposure to Quartz-tungsten-halogen (QTH) dental curing light for clinically relevant time periods to activate Photofrin^® and measured its effectiveness under a variety of conditions including activation through dentin hard tissue.S. intermedius was grown in planktonic suspension for 48 h. Nine groups were formed: three control groups (1-3) and six experimental groups (4-9). Groups 4-6 tested the use of Photofrin^® treatment combined with QTH light at various intervals of irradiation (5, 15 and 60 s). Groups 7-9 were similar to groups 4-6 with the exception that irradiation commenced through a dentin disc. Following treatment, bacteria were plated. Colony counts were measured following 72 h incubation at 37 °C. Statistical analysis was carried out by one-way ANOVA at a 95% confidence level.A significant reduction in S. intermedius colony counts was observed for all experimental groups and one control group. The reduction in numbers of colonies in the experimental groups varied from 79.28 to 99.40% with an average of 94.61%. Reduction in viable bacterial cells indicated a strong relationship between power density and irradiation interval. When curing light energy density was lower due to the irradiation through the 1 mm dentin disc, prolonged irradiation interval enhanced bacterial kill.In conclusion, where direct irradiation is not possible for PD treatment, irradiation through dentin may still be done successfully within a clinically relevant interval.     

Pharmacokinetic,toxicological and phototherapeutic studies of phthalocyanine ZnPcCF3

Photodynamic therapy (PDT) is an alternative modality for cancer therapy. It induces neoplasic cells death through photoachievable sensitizers. The aim of this work was to evaluate the pharmacokinetic, toxic and phototherapeutic effects of the phthalocyanine ZnPcCF₃ in a Balb/c mice tumor model. Biodistribution studies were carried out by intraperitoneal injection of 0.2 mg/kg ZnPcCF₃. Histological studies and serum biochemical parameters were used to evaluate hepatic and renal toxicity and functionality. After tumor irradiation (210 J/cm²), an analysis of tumor necrosis degree was used to evaluate the phototherapeutic effects. It was measured at 1, 2, 3 and 4 days after PDT. Vital staining was performed by intraperitoneal injection of 0.35 ml 1% Evans Blue solution. Six hours later, tumors were excised and examined. The unstained area was attributed to necrotic tissue, whereas the stained area showed tissue with preserved blood supply.     

Dynamics of interactions of photosensitizers with lipoproteins and membrane-models: correlation with cellular incorporation and subcellular distribution

The incorporation and subcellular localization of photosensitizers are critical determinants of their efficiency. Here, we correlate these properties with the interactions of photosensitizers with membrane-models and low density lipoproteins (LDL) in acellular systems. Focus was given on dynamics aspects. Two amphiphilic photosensitizers, deuteroporphyrin (DP) and aluminum phthalocyanine sulfonated on two adjacent isoindole units (AlPcS2a) were selected. The phthalocyanine was bound to LDL with an overall association constant around 5 x 10(7)M(-1). Biphasic association kinetics was indicative of two types of sites. The release of the phthalocyanine into the bulk aqueous medium occurred within less than a second. A similar behavior was found previously for deuteroporphyrin although its affinity was somewhat higher (5.5 x 10(8)M(-1)). Both compounds were previously characterized by high affinity for membrane-models and quick exchange with the bulk solution. However, they strongly differed by their rate of transfer through the lipid bilayer, in the range of seconds for the porphyrin, several hours for the phthalocyanine. In the case of the porphyrin, fluorescence microscopy on human fibroblasts showed diffuse labeling with no significant modification of the distribution upon vectorization by LDL. In contrast, the phthalocyanine was localized in intracellular vesicles. Vectorization by LDL favored lysosomal localization although little effect was found on the overall uptake as shown by extraction experiments. The role of lipoproteins in the cellular localization of photosensitizers is significantly more important for photosensitizers not freely diffusing through bilayers. The dynamics of the interactions of photosensitizers with membranes appears as an important determinant of their subcellular localization.     

Cell death and growth arrest in response to photodynamic therapy with membrane-bound photosensitizers

Photodynamic therapy (PDT) is a treatment for cancer and for certain benign conditions that is based on the use of a photosensitizer and light to produce reactive oxygen species in cells. Many of the photosensitizers currently used in PDT localize in different cell compartments such as mitochondria, lysosomes, endoplasmic reticulum and generate cell death by triggering necrosis and/or apoptosis. Efficient cell death is observed when light, oxygen and the photosensitizer are not limiting ("high dose PDT"). When one of these components is limiting ("low dose PDT"), most of the cells do not immediately undergo apoptosis or necrosis but are growth arrested with several transduction pathways activated. This commentary will review the mechanism of apoptosis and growth arrest mediated by two important PDT agents, i.e. pyropheophorbide and hypericin.     

两种光敏剂对鲜红斑痣光动力学疗法的疗效影响

目的 评价两种光敏剂对鲜红斑痣的光动力学疗法(PDT)疗效的影响,进一步评价该疗法治疗鲜红斑痣的有效性和安全性.方法 根据就诊顺序,将30例鲜红斑痣患者随机分成两组,每组15例,进行PDT,一组接受癌光啉(PSD-007),另一组接受血卟啉单甲醚(HMME),3个疗程后总结分析两种光敏剂对疗效的影响.结果 治疗3个疗程后,PSD-007组的患者完全治愈率为33.3%,明显高出HMME组的6.7%;显效率前者为100%,而后者仅为80%.结论 PSD-007作为光敏剂的光动力学疗法的疗效优于HMME-PDT;PDT治疗鲜红斑痣的疗效可靠、安全性好,值得临床进一步推广.     

Photodynamic therapy-mediated hypericin-loaded nanostructured lipid carriers against vulvovaginal candidiasis

Introduction and Aim: The indiscriminate use and adverse effects of the main conventional antifungal agents compromise the effectiveness of treating vulvovaginal candidiasis (VVC), mainly caused by the species Candida albicans. This study evaluated the effectiveness of photodynamic therapy (PDT) and the in vitro and in vivo anti-candida potential of the hypericin (HYP)-loaded nanostructured lipid carriers (NLC). Materials and Methods: Empty NLC and NLC-HYP were characterized by the dynamic light scattering technique and transmission electron microscopy to evaluate the average particle size distribution and its morphologies. The in vitro inhibition photodynamic effect of the systems was tested to reduce the planktonic viability of C. albicans. The therapeutic assay photodynamic of the systems was performed to treat VVC in mice. Results: Empty NLC and NLC-HYP presented values of average hydrodynamic diameter, polydispersity index, and ζ-potential from 136 to 133 nm, 0.16 to 0.22, and -18 to -30 mV, respectively, on day 30. Microscopically, the systems showed spherical morphologies and nanoscale particles. Furthermore, in the in vitro inhibition assay, the treatment of PDT with NLC-HYP (NLC-HYP+) showed a significant reduction of the C. albicans planktonic viability compared to YNB negative control after 5 min of LED light irradiation. In the in vivo therapeutic assay, the antifungal group (vaginal antifungal cream) and NLC-HYP+ evaluated in the dark and by PDT, respectively, had a significant log₁₀ reduction in fungal burden compared to the infected group on day 8 of the VVC treatment. Conclusion: Due to the in vitro and in vivo anti-candida potential, PDT-mediated systems can be an effective strategy in VVC therapy.