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Alzheimer's disease (AD) is a dementia-type neurodegenerative disease with an increasing incidence in elderly population and a poor prognosis. Therefore, the early diagnosis technology of AD urgently needs to be improved. In this paper, the laboratory diagnostic technologies of Alzheimer's disease were reviewed in the field of neuropsychological assessment, neuroimaging technology, and biomarker detection, including the simple intelligence state scale, the Montreal cognitive assessment scale, the memory and executive function screening scale, structural MRI, and functional MRI, positron emission computed tomography, MRI-based artificial intelligence analysis, and β amyloid (Aβ), homocysteine, S100B protein, Aβ 42, tau protein, urine AD-related neurofilament protein (AD7c-NTP) and Aβ plaques in the retinas. The limitations of these technologies were analyzed, and the development trends of the technologies were summarized. In order to improve the efficiency of AD screening, it is necessary to build an early diagnosis system for AD, in which multimodal diagnosis technology should be used to distinguish different types of AD.
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Metronomic photodynamic therapy (mPDT) is a new type of photodynamic therapy (PDT) that has received much attention in recent years. It has a similar therapeutic mechanism to traditional PDT, i.e. the photosensitizer is irradiated by visible light irradiation with a specific wavelength, and tissue oxygen photochemical reactions produce cytotoxic reactive oxygen species (ROS) that selectively kill rapidly proliferating tumor cells. Unlike traditional PDT, the photosensitizer and light in mPDT are continuously transmitted at a low time and at a low rate, and the specificity of tumor treatment is enhanced by apoptosis. In this paper, the current researches on the in vitro and in vivo effects and mechanisms of mPDT, as well as the research status of photosensitizers and light sources for in vivo research, were reviewed, with a view to understanding the existing mPDT technology and providing reference for the further studies. This review paper can provide a basic for promoting the clinical research and application of mPDT.
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Objective To explore the effects of 3-mercaptopropionic acid (3-MPA) coated CdSe-CdS/ZnS quantum dots (3-MPA-QDs) on the uptake , proliferation and migration of human umbilical vein endothelial cells (HUVEC), and to study the biotoxicity of 3-MPA-QDs, so as to provide the theoretical basis for the development of quantum dot photosensitizers . Methods The short-term ( 6 h ) uptakes of 3-MPA-QDs and the small molecule photosensitizer protoporphyrin IX (PpIX) in HUVEC cells were real-time observed and compared by a laser confocal scanning microscope. Besides, the uptakes within 48 h as well as the effects of the uptake on morphology and proliferation of HUVEC were also observed. The effect of 3-MPA-QDs on the migration of HUVEC cells within 24 h was observed using a grid dish. LysoTrackerTM Deep Red was used to label lysosomes, and the endocytosis mechanism of 3-MPA-QDs was observed by fluorescence co-localization. Results The fluorescence of 3-MPA-QDs in the HUVEC showed a continuous rising trend within 6 h, weakened after 24 h, and then turned weaker after 48h of the uptake, which is different from the"up-saturation"absorption pattern of PpIX. However, the fluorescence signal was still clear and bright which indicate 3-MPA-QDs were passaged into newborn cells. Migration experiments showed that the target cells carrying 3-MPA-QDs migrated 50 μm grids within 24 h, indicating the cell migration ability was not significantly affected. Co-localization results showed that 3-MPA-QDs localized in lysosomes. Conclusions The 3-MPA-QDs localized in lysosome, and they were easy to be absorbed and hard to be excreted by HUVEC. However, no obvious effects of 3-MPA-QDs were observed on cell proliferation and migration.
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Objective To evaluate the influence of dosage,operation method,adverse reaction of endoscopic photodynamic therapy (EPDT) on its therapeutic efficacy in rabbit models of in-situ rectal cancer,so as to provide preclinical basis of photodynamic therapy for rectal cancer.Methods 20 rabbits with in-situ VX2 rectal cancer were randomly divided into control group,PDT low dose group,intermediate dose group,and high dose group.At 24 h before PDT,photosensitizer (hermimether) was intravenously injected into rabbits.630 nm semiconductor laser was used as light source.The growth of the tumor was observed by conventional endoscopy and endoscopic ultrasonography,and the survival time,general conditions and adverse reactions were recorded.The histopathological changes were observed by hematoxylin-eosin staining.Results At 7 d after PDT,the total response rates of low dose,intermediate dose and high dose group respectively were 40％ (slight),80％ (60％ remarkable and 20％ slight),100％ (20％ remarkable and 80％ slight).The average survival times of the three groups were 14 d,10 d and 5 d,respectively.The main adverse reactions were inflammation,intestinal obstruction,intestinal peristalsis loss and death.Conclusions The dosage of PDT is an important factor to influence the curative effect.The appropriate dose of PDT will have a better effect on the treatment of rectal cancer.A thorough study of these problems is helpful to the clinical application of PDT in the treatment of rectal cancer.
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Objective To explore the killing effect of dielectric barrier discharge (DBD) plasma on tumor cells and to analyze the DBD-induced apoptosis mechanism.Methods Thiazolyl blue tetrazolium bromide (MTT) assay method was used to detect the killing effect of low temperature plasma on the cytotoxicity of normal spleen leukocytes and acute promyelocytic leukemia cells (LT-12) at different doses.The changes of reactive oxygen species (ROS) level were measured after plasma treatment.The cell apoptosis rate was detected by Annexin V/PI double staining at different doses.The expression of apoptosis-related genes and proteins was detected by qRT-PCR and Western Blot.Results MTT results showed that the killing effect of plasma treatment was dose-dependent and time-dependent.The cell survival rate after 8 hours of treatment decreased from 98％ to 63％ with the dose increasing from 30 s to 240 s.The survival rate decreased from 78％ (2 h) to 39％ (24 h) after the treatment with a same dose (e.g.240 s).Annexin V/PI double staining results demonstrated that the plasma effect can induce apoptosis,and the apoptosis rate was not only positively correlated with the plasma dose,but also with the post-plasma time.The longer the post-plasma time,the higher was the apoptosis rate.The apoptotic rate of the 60 s dose treatment after 12 h was 48％ that increased to 55.3％ with the dose of 120 s.The production of reactive oxygen species (ROS) detected by flow cytometry also showed a time correlation of the plasma treatment.After the plasma treatment,the ROS level immediately increased to 1.24 times,and sharply increased to 5.39 times after 20 h post-plasma.The experimental results of qRT-PCR and Western blot showed that the expression of the genes and proteins of Caspase family and Bcl-2 family was very active at 8 to 12 h post-plasma treatment.Conclusions Low-temperature plasma can effectively kill tumor cells,and apoptosis is the main mechanism of death.The molecular mechanism of apoptosis of tumor cells induced by low temperature plasma was preliminary confirmed.
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Objective To prepare 5-aminolevulinic acid (ALA) and hematoporphyrin monomethyl ether (HMME) hydrogel suppositories and to evaluate their photosensitizer transfer efficiencies in rectal tumor tissue.Methods The BALB/c mice implanted SW837 rectal cancer cells subcutaneously were randomly divided into four groups:intrarectal suppository administration group,cutaneous administration group,intratumoral injection group and intravenous injection group.Fluorescence spectrophotometry was used to measure the concentration of protoporphyrin Ⅸ (PpⅨ) and HMME in rectal wall,skin and tumor tissue.The distribution of photosensitizer was determined by a fluorescence spectroscopy system.Results The concentration of PpⅨ in the ALA suppository administration group was 9.76 times (1 h) and 5.80 times (3 h) higher than that in the cutaneous administration group,and the differences were statistically significant (all P＜0.05).The maximal penetration depth of ALA in tumor tissue was about 3-6 mm at 2 h after the cutaneous administration.After the HMME suppository administration,the concentration of HMME in the rectal wall was very low.The maximal penetration depth of HMME in tumor tissue was less than 2 mm after the cutaneous administration.Conclusions ALA is more likely to penetrate mucosal barrier compared to skin tissue.The hydrogel suppository based rectal administration is expected to be a new administration method for the rectal cancer photodynamic therapy using ALA.
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Objective To evaluate the efficacy of the systemic photodynamic therapy (SPDT)for treating leukemia using a Brown Norway myeloid leukemia (BNML) rat model.Methods The BNML rat model was established by injecting green fluorescent protein (GFP)-LT12 cells into the tail vein.After GFP-LT12 injection,the early-SPDT group,mid-SPDT group and late-SPDT group were treated with SPDT at 5,10 and 15 days,the negative control group was fed as usually,and the Ara-c positive control group was treated with Ara-c at 7 days.The GFP-LT12 cells were traced by a fluorescence imaging system.The GFP-LT12 cells in the tissues and organs were detected by flow cytometry.The levels of IFN-γ,IL-1α,IL-1β,IL-2,IL-4,IL-6,IL-10 and TNF-α in serum were detected by milliplex rat cytokine 9 kits.Results Compared with the negative control group,the survival times of the rats in the earlySPDT group,mid-SPDT group and the late-SPDT group were prolonged (all P＜0.05).The ratios of GFP-LT12 cells in pulp and liver were decreased in the late-SPDT group.The levels of IL-1β,IL-10,TNF-α and IFN-γin serum of the late-SPDT group were decreased (all P＜0.05).Conclusion The SPDT is an effective method for the treatment of leukemia,and the anti-tumor immune effect may play a key role in this process.
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Objective To study the effects of umbilical cord mesenchymal stem cells (UCMSCs) on the apoptosis of human breast cancer cell line MCF-7.Methods MCF-7 cells were co-cultured with different concentrations of UCMSCs.The apoptosis of MCF-7 cells was detected by in situ apoptosis and flow cytometry.Nude mouse subcutaneous tumor model was established by inoculating MCF-7 and MSCs cells subcutaneously on the right side of the back of a mouse.The MCF-7 cells were inoculated on the left side of the mouse as control.The tumor volume was measured every week to compare the difference between the two groups.On the 17th day after inoculation,the tumor tissue was harvested and the apoptosis of tumor cells was observed by a transmission electron microscopy.Results In situ apoptosis and flow cytometry showed that the early and late apoptosis rates of MCF-7 cells increased first and then decreased with the increase of UCMSCs concentration.The differences between the control and the MCF-7+UCMSCs group were statistically significant for early (F=39.80,P＜0.001) and late apoptosis rates (F=5.68,P＜0.01).The tumor volume of MCF-7+UCMSCs group was significantly lower than that of control group in 17 days after inoculation (F=9.81,P＜0.01).The representative apoptotic cells were observed by the transmission electron microscopyin the MCF-7 +UCMSCs group.Conclusion The UCMSCs with a certain concentration can effectively promote the apoptosis of MCF-7 cells.This study provides a certain experimental basis for the clinical treatment of breast cancer.
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Cell microencapsulation aims to wrap the living target cells by one or several materials with good biological compatibility and semipermeable membrane properties.Cell microencapsulation not only can achieve immune isolation and prevent the attacks by macromolecular immunes and immune cells,but also can allow the free access of metabolites,small molecule nutrients and bioactive substances to the microcapsule.With the continuous progress of interdisciplinary technologies,cell microencapsulation shows increasing application prospects of making up a variety of limitations of organ transplantation.Moreover,with the development and maturation of cell microencapsulation,it has shown a strong advantage in regenerative medicine,which will certainly promote the rapid development of artificial cells and artificial organs.In this paper,the preparation of cell microcapsules,the effects of the outer membrane of microcapsules on immunological macromolecules and cytokines,the immunogenicity of the outer membrane,and the representative applications of cell microencapsulation were summarized.
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Cell microencapsulation aims to wrap the living target cells by one or several materials with good biological compatibility and semipermeable membrane properties.Cell microencapsulation not only can achieve immune isolation and prevent the attacks by macromolecular immunes and immune cells,but also can allow the free access of metabolites,small molecule nutrients and bioactive substances to the microcapsule.With the continuous progress of interdisciplinary technologies,cell microencapsulation shows increasing application prospects of making up a variety of limitations of organ transplantation.Moreover,with the development and maturation of cell microencapsulation,it has shown a strong advantage in regenerative medicine,which will certainly promote the rapid development of artificial cells and artificial organs.In this paper,the preparation of cell microcapsules,the effects of the outer membrane of microcapsules on immunological macromolecules and cytokines,the immunogenicity of the outer membrane,and the representative applications of cell microencapsulation were summarized.
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Objective To investigate the protective effect of umbilical cord mesenchymal stem cells (UCMSCs) on traumatic brain injury (TBI) in rats.Methods Thirty healthy Sprague-Dawley rats (10 rats for each group) were randomly divided into normal control group (normal),model group (injection of saline after TBI) and UCMSCs transplantation group (injection of UCMSCs after TBI).The rats in experimental groups were sacrificed on the 10th day after UCMSCs transplantation.The percentage of UCMSCs in brain tissue was detected by flow cytometry.The pathological changes of brain tissue were observed by hematoxylin-eosin (HE) staining method.The expressions of vascular endothelial growth factor (VEGF),glial fibrillary acidic protein (GFAP) and brain-derived neurotrophic factor (BDNF) in brain tissue were measured by immunohistochemistry and immunofluorescence double staining.The neurological deficit was evaluated by neurological deficit degree.Results The percentage of CD90,CD73 and CD105 cells in the UCMSCs transplantation group was significandtly higher than that in the model group (0.4％ vs 0.1％,P＜0.05).The results of HE staining showed that the brain injury of the transplanted group was alleviated compared with the model group (P＜0.05).The VEGF of the brain tissue in injury area in the UCMSCs transplantation group was higher than that in the model group (P＜0.05).The number of GFAP and BDNF positive cells in the UCMSCs transplantation group was higher than that in the model group (P＜0.05),and the neurological deficit score was also higher than that in the model group (P＜0.05).Conclusions UCMSCs transplantation for the treatment of TBI rats can effectively reduce the vascular damage in the injury area and promote nerve recovery.
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<p><b>OBJECTIVE</b>To investigate the reactive characteristics of normal vocal cord tissues to photodynamic therapy (PDT) and the damage effects of different concentration of photosensitizer and different light on normal rabbit vocal cord. Making the preliminary research of PDT in clinical treatment of chronic inflammation of the vocal cords and precancerous lesions.</p><p><b>METHODS</b>Twenty-five healthy Japanese big ear experimental rabbits were randomly divided into 5 groups: low work rate low dose group A (100 mW, 10%5-ALA), high work rate low dose group B (200 mW, 10%5-ALA), high work rate high dose group C (200 mW, 20%5-ALA), low work rate high dose group D (100 mW, 20%5-ALA) and normal control group E. The issue damage and wound recovery were observed in 1 d, 3 d, 7 d, 14 d, 28 d after intervention.</p><p><b>RESULTS</b>A severe inflammation reaction was observed in group A, B, C, D after intervened with PDT compared to normal group. The reaction of group A was lighter, and the reaction of group C was the most serious. The content of collagenous fiber, hyaluronic acid and fibronectin in vocal fold lamina layer was significantly higher than that in normal group (P<0.05). Different degrees of fiber proliferation were observed in all groups. The content of each component of vocal fold lamina layer tended to be normal slightly higher level in 28 d. Observation by electron microscope showed that there were no significant differences in A, B, C, D, E in 28 d after intervention.</p><p><b>CONCLUSION</b>Recoverable damage repair process can be detected in rabbit vocal after intervened with PDT, which began in 7 d and basically completed in 28 d. In a certain concentration (10%-20%) and dose range (100-200 mW). The higher of photodynamic dose, the more serious of the damage. And the damage was basically reversible.</p>
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Animals , Rabbits , Laryngeal Diseases , Drug Therapy , Light , Photochemotherapy , Vocal Cords , Wounds and Injuries , Pathology , Wound HealingABSTRACT
Objective To investigate the photochemotherapeutic effect and the main affecting factors of PSD-007 on human cervical cancer Hela in vitro.Methods Hela cells were treated with different concentrations of PSD-007 (0,3.125,6.25,12.5,25,50,100 μg/ml) for 2 h under the influence of low-level laser (635 nm) therapy at different doses (0,0.6,1.2,2.4,4.8,9.6 J/cm2).Then the OD values and survival rates of Hela cells were measured by MTT assay compared with breast cancer cells MCF-7 in same treatment.Hela cells were treated with 12.5 μg/ml of PSD-007 for 2 h and were treated with different intensities of laser (1.2,2.4,4.8 J/cm2).The cellular apoptosis rate and cell cycle phase distribution of Hela were measured by a flow cytometry (FCM).Results Survival rates of Hela cells declined with more than 25 μg/ml of PSD-007 only,and significant difference in the inhibitory between the PDT group and control group was observed (P＜0.05).The survival rates of Hela after PDT was decreased by the concentration of sensitizer and dose of laser.There were no significant differences of cell survival rates among the groups with concentrations more than 12.5 μg/ml and laser energy density more than 4.8 J/cm2.The FCM assay showed a G0/G1 cell cycle arrest in a time-dependent manner.Conclusions PSD-007 has a photodynamic effect on Hela in vitro.Photodynamic effect of PSD-007 was more significant in Hela than MCF-7.Less photosensitizer and laser energy density were needed.
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Objective To evaluate the bactericidal effect of diode laser on Porphyromonas gingivalis (Pg),and to explore an optimized protocol for a safe dose of photodynamic therapy (PDT) to eliminate periodontal pathogens as well as the impact on the implant surfaces,so as to provide theoretical and experimental basis for PDT in periimplantitis therapy.Methods Artificial in vitro models were formatted by culturing Pg standard strain and ITI (International Team for Implantology) implants together in CDC broth.Then artificial in vitro models were treated by different doses of hematoporphyrin monomethyl ether (HMME) and different energy density of laser (EDL) for 60 s.The cultures were counted by colony form unit (CFU),and SPSS 17.0 statistical software was used for data statistical analysis to select the best EDL and HMME dose.Finally,ITI implants were observed by scanning electron microscope (SEM) to evaluate the impact of HMME-PDT on Pg of implant surfaces.Results When EDL was 12 J/cm2 and mass concentration of HMME was 25 μg/ml,SEM observations showed that PDT could effectively kill Pg ((13.00±5.00) CFU)without damaging the implant surfaces.Conclusions PDT therapy combining 630 nm diode laser with photosensitizer HMME have good bactericidal effect on Pg,and the EDL and HMME dose is as small as the clinical applicable safe dose.
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Objective To investigate the pharmacokinetic characteristics of PSD-007 in BN rats.Methods Blood of the BN rats was collected from the inner canthus after iv administration of PSD-007,and the plasma drug concentrations at different times were determined by fluorescent spectrometry.The best compartment model and the pharmacolinetic were calculated by the software of DNS 2.0.Results The elimination process of PSD-007 fitted three-compartment open model after iv administration.The principal pharmacokinetic parameters were t1/2α=0.096 h,t1/2β=1.299 h,t12γ=19.387 h,V1=0.259 L/kg,A UC=15.263 mg/(L ·h).Conclusions The sensitivity of fluorescent spectrometry was high and the operation is sinple and the progress is short.PSD-007 has fast absorption,quick effect and elimination without accumulation phenomenon.
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Objective To evaluate the combined effects of photodynamic therapy (PDT) with PSD-007 and cytarabine (Ara-c) on human acute promyelocyte leukemia cell HL-60.Methods The experiments were divided into four groups:control group,PDT-only groups (PDT 1-4 groups:the combination of PSD-007 concentrations (5 μg/ml and 7.5 μg/ml) and the energy density of laser (EDL) (1.2 J/cm2 and 2.4 J/cm2),Ara-c-only groups (Ara-c A group:0.3μg/ml,Ara-c B group:1.2μg/ml) and combination groups (the pair-wise combinations of the PDT doses and Ara-c doses above).All combination groups were treated with three treating methods,including P24A (the cells were treated with PDT for 24 h,and then cocultured with Ara-c for another 24 h),A24P (treated with Ara-c for 24 h before PDT,and then cocultured with PDT for 24 h),and PA24 (treated with the Ara-c and PDT for 24 h).CCK-8 method was used to test the cell viability,and the combined effect was analyzed using King formula.The changes of cell cycles were analyzed using flow cytometry.Results In the case of low-dose PDT,the combination groups showed coordinated effect with all three methods,whereas in the case of high-dose PDT,they showed additive or coordinated effect in P24A and A24P,but it showed antagonistic effect in the schedule of PA24.Cell cycles were inhibited to G0/G1 phase by both PDT and Ara-c.Conclusions Coordinated effects could be found when HL-60 cells were treated with the combination of Ara-c and PDT.The effects depended on the dose of Ara-c and PDT and the operation schedules.The effects at low dose were more obvious than that of high dose,and allowing a 24 h period in between the addition of PDT and Ara-c also promoted the effects.
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Objective To preliminarily investigate the therapeutic effect of photodynamic therapy (PT) treating allergic rhinitis (AR).Methods Eighteen New Zealand rabbits were randomly divided into 3 groups,experimental group A,negative control group B and blank control group C.Rabbits of A and B groups were sensitized with ovalbumin (OVA) to get animal AR model.Group A was treated with PDT while group B and C were applied with natural light treatment.Symptoms and signs before and after treatment were compared and the change of nasal mucosa was observed with light microscope and transmission electron microscope.Results After PDT treatment,group A rabbits' AR symptoms and signs were improved significantly compared to group B,light microscope and transmission electron microscope observation showed that the number of inflammatory cells of group A rabbits decreased significantly and the mucosal structure returned to normal after PDT treatment.After 21 d,as compared with group C,the differences of the times of sneezing and scratching and nasal secretion had no statistical significance (P＞0.05).Conclusions PDT has certain therapeutic effect in experimental AR treatment,which can be used in AR treatment after consummating its therapeutic mechanism.
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Objective The dose and type of light and photosensitizer could seriously affect the curative effect of photodynamic therapy (PDT).The purpose of this study was to observe whether or not PDT with hematoporphyrin monomethyl ether (HMME) can cure laryngocarcinoma in the solid tumor model,and to define the proper laser amount for killing the cancer cells.Methods Forty eight BALB/c mouse models with subcutaneous Hep-2 laryngeal carcinomas were prepared.Mice were divided into six groups depending on the amount of laser received from 30 J/cm2 to 480 J/cm2 including a control group,tumor size in each group was between 8 mm and 10 mm.Tail vein injection were given with HMME prior to applying the laser light,and then illumination was carried out on the tumor at 3 h after HMME administration.Tumor volume,animal weight and histopathologic changes were observed after PDT.Results All mice apparently showed positive results via PDT,and the cancer had been cured in 120 J/cm2 and 480 J/cm2 groups.The laryngeal cancer lesions began to form scab 1 d after PDT and the scab became hard and black after 5 d.The tumor regression began simultaneously and completed around 30 d after PDT.Conclusions PDT may treat laryngeal cancers which sized less than 10 mm in mouse models.The optimum energy to destruct the laryngeal cancer cells may be 120 J/cm2.
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<p><b>OBJECTIVE</b>To study the reactive changes of normal nasal mucosa in rabbit under photodynamic therapy (PDT) and to make a preliminary research for the treatment of allergic rhinitis (AR) with PDT.</p><p><b>METHODS</b>Twenty-four New Zealand rabbits were divided into 2 groups, an experimental group and a control group with 12 rabbits in each group. PDT was applied to the experimental group, while the control group was given no treatment. The nasal mucosa was sampled separately from the same position of the rabbits from the 2 groups on 1st, 3rd, 7th, 14th, 21st, 28th day. Histomorphological changes of the sampled nasal mucosa were observed under light microscope and transmission electron microscope (TEM). The damage of three tachykinins: substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) of nerve fibers was observed after immunohistochemical staining.</p><p><b>RESULTS</b>Compared with the control group, the nasal mucosa tissues from the experimental group had serious inflammatory reaction with basal layer damaged on the 1st and 3rd day after PDT application, the epithelial cells of nasal mucosa were arranged in disorder, and part of cilium shortened and became abnormal or even disappeared, each organelles damaged obviously; on the 7th, 14th, 21st day, it could be seen that ciliated cell, columnar cell and goblet cell started regeneration, basal cell and lamina propria glands proliferated, and the glands appeared secretion phenomenon; on the 28th day, ciliated columnar epithelium took back the nasal mucosas with small amount of microvilli, and mucous granules were found in the column cells. Nasal immunohistochemical staining of the experimental group from various stages showed that three kinds of neuropeptides were not expressed.</p><p><b>CONCLUSIONS</b>Normal rabbit nasal mucosas will be temporarily damaged after PDT application, the damaged nasal mucosa begin to recover in one week, and return to normal in about four weeks. Most structure and functions have recovered at the fourth week except some nerve endings.</p>
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Animals , Rabbits , Cilia , Inflammation , Nasal Mucosa , Neuropeptides , Photochemotherapy , Substance PABSTRACT
Objective The purpose of this study was to assess the antibacterial effects of hematoporphyrin monomethylether-photodynamic therapy (HMME-PDT) on Enterococcus faecalis within infected simulated lateral canals in vitro with different energy.Methods Simulated lateral canals were prepared on extracted teeth.The specimens were infected with Enterococcus faecalis and then were randomly divided into eight groups.Group A was considered as negative control,its specimens were irrigated with physiological saline.Group B was the positive control,they were irrigated with 5.25％ NaClO.Other groups were incubated with HMME at concentration of 40 μg/ml for 5 min,followed by exposure to light at 532 nm for 120 s with different powers in a spiral pattern.Groups were named C-H,in corresponding with the power 50,60,70,80,90,100 mW.Microbial samples (the dentin chips from simulated lateral canals) were taken before and after the treatments.The survival fractions in each simulated lateral canal was calculated by counting colony-forming units(CFUs).Results 1.The HMME-PDT-treated groups resulted in a significant reduction in the number of E.faecalis in simulated lateral canals compared with the negative controls(P＜0.05).2.The antibacterial effects of group D、E、F、G、H were higher than the NaCl0-irrigated group(P＜0.05).3.The difference of antibacterial effects between the F、G、H groups was in significant(P＞0.05).Conclusion HMME-PDT had significant inhibitive efficacy on Enterococcus faecalis within infected simulated lateral canals and the efficacy was power-depended.It can play the best effect with the power of 80 mW.