Efficient fluorescence detection of protoporphyrin IX in metastatic lymph nodes of murine colorectal cancer stained with indigo carmine

Protoporphyrin IX (PpIX), a biochemical converted from 5-aminolevulinc acid (5-ALA) in living cells, is useful for intraoperative fluorescent detection of cancer metastasis in lymph nodes (LNs). However, unknown is whether the fluorescence of PpIX can be detected in the LNs when they coexist with indigo carmine, a blue dye commonly used for identification of sentinel LNs during surgery. To address this issue, we sought to evaluate the diagnostic usefulness of PpIX fluorescence in the presence of indigo carmine in a mouse LN metastasis model of rectal cancer after administration of 5-ALA. Spectral analysis of pure chemicals revealed that the absorption spectrum of indigo carmine widely overlapped with the fluorescence spectrum of PpIX specifically at the peak of 632 nm, a common emission wavelength for detecting PpIX, but not at the other peak of 700 nm. Due to such spectral overlap, the PpIX fluorescence intensity was significantly attenuated by mixture with indigo carmine at 632 nm, but not at 700 nm. Accordingly, fluorescent measurements of the mouse metastatic LN revealed more intense presentation of PpIX at 700 nm than at 632 nm, indicating that the diagnostic usefulness is greater at 700 nm than at 632 nm for the indigo carmine-dyed LNs after administration of 5-ALA. From these observations, we propose that the fluorescence measurement is more efficient at 700 nm than at 632 nm for detection of PpIX in metastatic LNs stained with indigo carmine.     

An in vitro diagnosis of oral premalignant lesion using time-resolved fluorescence spectroscopy under UV excitation—a pilot study

In spite of rapid advancement in cancer treatment, early diagnosis of cancer and medicable precursors are still the finest approach towards the assurance of patient lives and enhancement in the quality of their life. In this regard, the present study deals with the time-resolved fluorescence spectroscopy of normal and premalignant oral tissues under UV excitations (280 nm and 310 nm). The decay kinetics at 350 nm emission of normal tissues exhibit higher fluorescence lifetime than that of premalignant tissues and subsequent statistical analysis shows that the data were statistically significant. Further, the decay kinetics at 450 nm emission for normal and premalignant oral tissues was obtained. Subsequently, statistical analysis revealed that except fast component, rest of the component lifetimes and fractional amplitudes were not statistically significant. An attempt has also been made to explore the better statistical tool to discriminate premalignant tissues from normal ones at 350 nm emission. Among stepwise linear discriminant analysis (SLDA) and receiver operator characteristics (ROC), the former discriminates premalignant from normal tissues with 86.7% specificity and 93.3% sensitivity. Hence, fluorescence lifetime spectroscopy at 350 nm emission opens a new avenue for early detection of oral cancer.     

Fluorescence analysis of a tumor model in the chorioallantoic membrane used for the evaluation of different photosensitizers for photodynamic therapy

The development of a tumor in the chicken chorioallantoic membrane (CAM) enables a more individualized understanding of the dynamics of the photosensitizer (PS) interaction with the tumor blood vessels and cells. Photogem^® and 5-aminolevulinic acid (ALA), a protoporphyrin IX (PpIX) precursor, were used as PS and their red fluorescence enabled the monitoring of PS dynamic distribution in the vessels and in the tumor. With a tumor model in CAM and fluorescence assessment, the aim of this study was to evaluate the PDT parameters comparing different photosensitezers. In this model, the topical application was chosen as the best way of drug delivery and widefield fluorescence images were at every 30 min. The images were processed in a MATLAB^® routine for a semi-quantitative analysis of the red fluorescence. PpIX formation in the blood vessels and in the tumor region was observed after 3 h and 1.5 h, respectively, whereas Photogem^® was accumulated in the tumor region after 2 h. The illumination was performed by a diode laser with emission centered at 635 nm and irradiance of 80 mW/cm² for 10 min. After PDT irradiation, the photobleaching for both compounds was observed. Photogem^® showed a reduced photobleaching, however, both PS induced a destruction of the tumor mass and vascular network in the treated area.     

Assessing daylight & low-dose rate photodynamic therapy efficacy,using biomarkers of photophysical,biochemical and biological damage metrics in situ

BackgroundSunlight can activate photodynamic therapy (PDT), and this is a proven strategy to reduce pain caused byconventional PDT treatment, but assessment of this and other alternative low dose rate light sources, and their efficacy, has not been studied in an objective, controlled pre-clinical setting. This study used three objective assays to assess the efficacy of different PDT treatment regimens, using PpIX fluorescence as a photophysical measure, STAT3 cross-linking as a photochemical measure, and keratinocyte damage as a photobiological measure.MethodsNude mouse skin was used along with in vivo measures of photosensitizer fluorescence, keratinocyte nucleus damage from pathology, and STAT3 cross-linking from Western blot analysis. Light sources compared included a low fluence rate red LED panel, compact fluorescent bulbs, halogen bulbs and direct sunlight, as compared to traditional PDT delivery with conventional and fractionated high fluence rate red LED light delivery.ResultsOf the three biomarkers, two had strong correlation to the PpIX-weighted light dose, which is calculated as the product of the treatment light dose (J/cm²) and the normalized PpIX absorption spectra. Comparison of STAT3 cross-linking to PpIX-weighted light dose had an R = 0.74, and comparison of keratinocyte nuclear damage R = 0.70. There was little correlation to PpIX fluorescence. These assays indicate most of the low fluence rate treatment modalities were as effective as conventional PDT, while fractionated PDT showed the most damage.ConclusionsDaylight or artificial light PDT provides an alternative schedule for delivery of drug-light treatment, and this pre-clinical assay demonstrated that in vivo assays of damage could be used to objectively predict a clinical outcome in this altered delivery process.     

Combination of hand-held probe and microscopy for fluorescence guided surgery in the brain tumor marginal zone

BackgroundVisualization of the tumor is crucial for differentiating malignant tissue from healthy brain during surgery, especially in the tumor marginal zone. The aim of the study was to introduce a fluorescence spectroscopy-based hand-held probe (HHF-probe) for tumor identification in combination with the fluorescence guided resection surgical microscope (FGR-microscope), and evaluate them in terms of diagnostic performance and practical aspects of fluorescence detection.Material and MethodsEighteen operations were performed on 16 patients with suspected high-grade glioma. The HHF-probe and the FGR-microscope were used for detection of protoporphyrin (PpIX) fluorescence induced by 5-aminolevulinic acid (5-ALA) and evaluated against histopathological analysis and visual grading done through the FGR-microscope by the surgeon. A ratio of PpIX fluorescence intensity to the autofluorescence intensity (fluorescence ratio) was used to quantify the spectra detected by the probe.ResultsFluorescence ratio medians (range 0 – 40) measured by the probe were related to the intensity of the fluorescence in the FGR-microscope, categorized as “none” (0.3, n = 131), “weak” (1.6, n = 34) and “strong” (5.4, n = 28). Of 131 “none” points in the FGR-microscope, 88 (67%) exhibited fluorescence with the HHF-probe. For the tumor marginal zone, the area under the receiver operator characteristics (ROC) curve was 0.49 for the FGR-microscope and 0.65 for the HHF-probe.ConclusionsThe probe was integrated in the established routine of tumor resection using the FGR-microscope. The HHF-probe was superior to the FGR-microscope in sensitivity; it detected tumor remnants after debulking under the FGR-microscope. The combination of the HHF-probe and the FGR-microscope was beneficial especially in the tumor marginal zone.     

Differences in the intensity of light-induced fluorescence emitted by resin composites

BackgroundThe aims of this study were to compare the intensities of fluorescence emitted by different resin composites as detected using quantitative light-induced fluorescence (QLF) technology, and to compare the fluorescence intensity contrast with the color contrast between a restored composite and the adjacent region of the tooth.MethodsSix brands of light-cured resin composites (shade A2) were investigated. The composites were used to prepare composite discs, and fill holes that had been prepared in extracted human teeth. White-light and fluorescence images of all specimens were obtained using a fluorescence camera based on QLF technology (QLF-D) and converted into 8-bit grayscale images. The fluorescence intensity of the discs as well as the fluorescence intensity contrast and the color contrast between the composite restoration and adjacent tooth region were calculated as grayscale levels.ResultsThe grayscale levels for the composite discs differed significantly with the brand (p < 0.001): DenFil (10.84 ± 0.35, mean ± SD), Filtek Z350 (58.28 ± 1.37), Premisa (156.94 ± 1.58), Grandio (177.20 ± 0.81), Charisma (207.05 ± 0.77), and Gradia direct posterior (211.52 ± 1.66). The difference in grayscale levels between a resin restoration and the adjacent tooth was significantly greater in fluorescence images for each brand than in white-light images, except for the Filtek Z350 (p < 0.05). However, the Filtek Z350 restoration was distinguishable from the adjacent tooth in a fluorescence image.ConclusionsThe intensities of fluorescence detected from the resin composites varied. The differences between the composite and adjacent tooth were greater for the fluorescence intensity contrast than for the colors observed in the white-light images.     

Endobronchial photodynamic therapy under fluorescence control: Photodynamic theranostics

BackgroundPhotodynamic therapy (PDT) has several advantages. However, one of the disadvantages is its inability to be individualized according to biological characteristics of malignant tumors. The objective of this study was to investigate a strategy for individualized endobronchial PDT in the treatment of centrally located non-small cell lung cancer.MethodsNew approach suggests taking fluorescence-based measurements of chlorine E6 photosensitizer (PS) accumulation in the malignant tumor tissue, and assess PS consumption rate during PDT. Two randomized groups of 45 patients took part in the comparative study of standard PDT procedure, 662 nm, pulse-periodic mode, therapeutic light (reference group – RG) versus the investigated individualized approach under fluorescence control after irradiation with violet light, 408 nm, diagnostic light (study group – SG). The PDT-treatment parameters and results of follow-up bronchoscopy were compared between the groups.Results43 (96%) of 45 patients in SG demonstrated intense fluorescence in the area of the tracheal/bronchial tumor stenosis. 4 (9%) of 45 patients (SG) demonstrated fluorescence of mucosa areas distant from the main tumor lesion after violet light irradiation. Mean fluence during the whole PDT procedure was 95 ± 20 J/cm² (range 60–130 J/cm²), which was significantly lower than in RG (p = 0.01). Total exposure time was significantly lower in SG (365 ± 65 s), compared with RG (690 ± 65 s), P = 0.001. According to the follow-up bronchoscopy the difference in the PDT-treatment results between the groups is statistically insignificant.ConclusionsThe investigated strategy suggests using fluorescence control of the efficacy of PDT-treatment (photodynamic theranostics) to optimize and individualize the PDT procedure.     

A quantitative study of in vivo protoporphyrin IX fluorescence build up during occlusive treatment phases

BackgroundTopical photodynamic therapy (PDT) is a non-invasive light based therapy used to treat non-melanoma skin cancer (NMSC) and dysplasia. During PDT, the light sensitive molecule protoporphyrin IX (PpIX) is activated, resulting in the production of singlet oxygen, which subsequently leads to cell death. PpIX is metabolised from a topically applied pro-drug and the strong fluorescence signal associated with PpIX can be utilised as an indicator of the amount of PpIX present within the tumour tissue. In this work we measure the build up PpIX during the occlusive treatment phase and investigate how the PpIX production rate is affected by different lesion and patient characteristics.MethodsFluorescence measurements were used to investigate the build up of PpIX within the tumour tissue during the 3 h long occlusive treatment prior to irradiation. The study included in vivo measurements of 38 lesions from 38 individual patients. Actinic keratosis (AK) and basal cell carcinoma (BCC) were the lesion types included in this study. The resulting data from the study was analysed using generalised linear mixed effects models.ResultsIt was found that the surface fluorescence signal linearly increased with occlusive treatment time. The predictive models suggest that there is a significant difference in PpIX production between lesion location, however no significant difference is demonstrated between different lesion types, gender and skin type.ConclusionsThe study extends and supports previous knowledge of PpIX production during the occlusive treatment phase.     

Plum-blossom needling promoted PpIX fluorescence intensity from 5-aminolevulinic acid in porcine skin model and patients with actnic keratosis

Background and objectivesPlum-blossom needling might enhance transdermal penetration of topically applied drugs by creating vertical channels. The purpose of this study was to evaluate drug delivery assisted by plum-blossom needling comparing with CO2 laser ablative fractional resurfacing (AFR) using 5-aminolevulinic acid (5-ALA), a porphyrin precursor, as a test drug.Materials and methodsEx vivo porcine skin was treated with plum-blossom needle(HWATO, Suzhou medical supplies factory Co., Ltd. China) or CO2 laser AFR before topical application of 20% 5-ALA(Sigma-Aldrich, Co., USA)cream, placebo cream and no cream. ALA-induced porphyrin fluorescence was measured by fluorescence microscopy at skin depths down to 1800 μm. Needling was done by tapping the skin vertically from 5 cm high above quickly. AFR was performed with a 10.6 μm wavelength prototype CO2 laser, using stacked single pulses of 3 millisecond and 91.6 mJ per pulse. Plum-blossom needling after ALA application was also done. Fluorescence intensity on lesion surface was examined by curalux spectrum analyzer (Laser Institute of Munich University, Germany) and VAS pain score was recorded in a randomized split-lesion clinical trial including 6 patients, 8 actinic keratosis lesions.ResultsAFR created regular cone-shaped channels surrounded by a 70 μm thin layer of thermally coagulated dermis, respectively. The cone is approximately 200 μm in diameter at the opening and 1850 μm in depth. Plum-blossom needle created irregular cone-shaped channels of approximately 180 μm in diameter at the opening and it always drags a tail—which was shaped from the closed deeper channels. There was no porphyrin fluorescence in placebo cream or untreated skin sites. Plum-blossom needling followed by ALA application enhanced drug delivery with significantly higher porphyrin fluorescence at the edge of hole (P < 0.005) and 100 μm far from the hole (P = 0.000) versus AFR followed by ALA application at skin depths of 120 and 500 μm. Needling after ALA application presented higher porphyrin fluorescence at the edge of hole at skin depths of 120 μm (P < 0.005) and lower porphyrin fluorescence at 1000 μm deep hole edge, and 100 μm far from the hole at 120 μm, 500 μm and 1000 μm depths versus AFR followed by ALA application (P < 0.005). Skin massage after ALA application did not affect ALA-induced porphyrin fluorescence after pretreatment of plum-blossom needling or AFR. ALA application after plum-blossom needling was better than before plum-blossom needling. The clinical trial showed that the surface fluorescence intensity was stronger in needle-pretreated-lesion than in laser-pretreated-lesion. While the VAS pain score between needle treatment and laser treatment was almost the same.ConclusionsPlum-blossom needling facilitates delivery of topical ALA into the dermis. It may help ALA to diffuse a little more broadly than AFR does in superficial dermis and obtain similar clinical effect with a much lower cost. Plum-blossom needling treatment appears to be a clinically practical and economical means for enhancing transdermal delivery of ALA, a photodynamic therapy drug, and presumably many other topical skin medications.     

A new screening method to detect proximal dental caries using fluorescence imaging

ObjectivesThis study aimed to assess the screening performance of the quantitative light-induced fluorescence (QLF) technology to detect proximal caries using both fluorescence loss and red fluorescence in a clinical situation. Moreover, a new simplified QLF score for the proximal caries (QS-Proximal) is proposed and its validity for detecting proximal caries was evaluated as well.MethodsThis clinical study included 280 proximal surfaces, which were assessed by visual-tactile and radiographic examinations and scored by each scoring system according to lesion severity. The occlusal QLF images were analysed in two different ways: (1) a quantitative analysis producing fluorescence loss (ΔF) and red fluorescence (ΔR) parameters; and (2) a new QLF scoring index. For both quantitative parameters and QS-Proximal, the sensitivity, specificity, and area under the receiver operating characteristic curve (AUROC) were calculated as a function of the radiographic scoring index at the enamel and dentine caries levels.ResultsBoth ΔF and ΔR showed excellent AUROC values at the dentine caries level (ΔF = 0.860, ΔR = 0.902) whereas a relatively lower value was observed at the enamel caries level (ΔF = 0.655, ΔR = 0.686). The QS-Proximal also showed excellent AUROC ranged from 0.826 to 0.864 for detecting proximal caries at the dentine level.ConclusionThe QS-Proximal, which represents fluorescence changes, showed excellent performance in detecting proximal caries using the radiographic score as the gold standard.     

Photodynamic action of palmatine hydrochloride on colon adenocarcinoma HT-29 cells

Palmatine hydrochloride (PaH) is a natural active compound from a traditional Chinese medicine (TCM). The present study aims to evaluate the effect of PaH as a new photosensitizer on colon adenocarcinoma HT-29 cells upon light irradiation. Firstly, the absorption and fluorescence spectra of PaH were measured using a UV–vis spectrophotometer and RF-1500PC spectrophotometer, respectively. Singlet oxygen (¹O₂) production of PaH was determined using 1, 3-diphenylisobenzofuran (DPBF). Dark toxicity of PaH was estimated using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Cellular uptake of PaH in HT-29 cells was detected at different time intervals. Subellular localization of PaH in HT-29 cells was observed using confocal laser fluorescence microscopy. For photodynamic treatment, HT-29 cells were incubated with PaH and then irradiated by visible light (470 nm) from a LED light source. Photocytotoxicity was investigated 24 h after photodynamic treatment using MTT assay. Cell apoptosis was observed 18 h after photodynamic treatment using a flow cytometry with Annexin V/PI staining. Results showed that PaH has an absorption peak in the visible region from 400 nm to 500 nm and a fluorescence emission peak at 406 nm with an excitation wavelength of 365 nm. PaH was activated by the 470 nm visible light from a LED light source to produce ¹O₂. Dark toxicity showed that PaH alone treatment had no cytotoxicity to HT-29 cancer cells and NIH-3T3 normal cells after incubation for 24 h. After incubation for 40 min, the cellular uptake of PaH reached to the maximum and PaH was located in mitochondria. Photodynamic treatment of PaH demonstrated a significant photocytotoxicity on HT-29 cells. The rate of cell death increased significantly in a PaH concentration-dependent and light dose-dependent manner. Further evaluation revealed that the early and late apoptotic rate of HT-29 cells increased remarkably up to 21.54% and 5.39% after photodynamic treatment of PaH at the concentration of 5 μM and energy density of 10.8 J/cm². Our findings demonstrated that PaH as a naturally occurring photosensitizer has potential in photodynamic therapy on colon adenocarcinoma.     

Clinical assessment of oral malodor using autofluorescence of tongue coating

ObjectivesThe aim of this study was to evaluate whether a new method using quantitative light-induced fluorescence-digital (QLF-D) was appropriate for the diagnosis of oral malodor by quantifying the fluorescence of tongue coating.MethodsThis study examined 103 healthy subjects who have an oral malodor as a main complaint. The levels of oral malodor were measured by organoleptic scores (OLS) and volatile sulfur compound (VSC) levels. The fluorescent tongue coating images captured by QLF-D were quantified as the integrated fluorescence score (IF score) by multiplying the intensity and area of fluorescence. The correlations between the fluorescence parameters and OLS as well as VSC levels and the diagnostic accuracy of the IF score were evaluated.ResultsThe IF score of tongue coating showed a significant positive correlation with the OLS (r = 0.54, p < 0.01) and the VSC levels (r = 0.49, p < 0.01). This score was significantly differed with the level of oral malodor (p < 0.001), and its AUC was 0.72 in identifying the patient with definite oral malodor (≥OLS 2).ConclusionsA new method quantifying tongue coating fluorescence detected by QLF-D can be used to diagnose oral malodor and assess its severity in the clinical practice.     

Phototoxicity in a laryngeal cancer cell line enhanced by a targeting amphiphilic chlorin photosensitizer

BackgroundPhotodynamic therapy (PDT) has been established in several countries as an alternative therapy for the treatment of various malignancies. This therapy involves the incorporation of a photosensitizer (PS) that is activated by visible light and form reactive oxygen species leading to target cell death by apoptosis or necrosis. Previously, our group has demonstrated that CHL-T (semi-synthesized from chlorophyll a and containing a linked solubilizing group TRISMA^®) presented a pronounced potential to induce death in HeLa cell line after PDT. In the present study, besides confirm the high cytotoxicity in another cell line, we have further investigated the cell death mechanisms caused by CHL-T as a photosensitizer in laryngeal carcinoma cells.MethodsCells were exposed to different concentrations of three photosensitizers, namely, hypericin (HY), unmodified chlorin (CHL) and a synthesized amphiphilic chlorin derivative (CHL-T). PSs accumulation and localization were accessed by fluorescence assays. Photosensitization was induced at 6 J cm⁻² using red LEDs (630 ± 10 nm). Viability was assessed by mitochondrial function (MTT); whereas apoptosis/necrosis was evaluated by fluorescence microscopy and flow cytometry. Expression of pro-apoptotic p53 protein was studied by Western blot.Results and conclusionsAll PS showed similar localization profile in the HEp-2 cells. The use of CHL-T increased the percentage of apoptotic cells and also p53 expression in comparison with the use of HY and CHL as photosensitizers. This study shows a significant effect of CHLT associated with red light (630 ± 10 nm and 18 mW cm⁻²) irradiation on a cancer cell line, indicating the potential of this amphiphilic chlorin in enhancing the therapeutic effectiveness of Photodynamic Therapy (PDT).     

Heptamethine cyanine based 64Cu-PET probe PC-1001 for cancer imaging: Synthesis and in vivo evaluation

PurposeDevelopment of a heptamethine cyanine based tumor-targeting PET imaging probe for noninvasive detection and diagnosis of breast cancer.MethodsTumor-specific heptamethine–cyanine DOTA conjugate complexed with Cu-64 (PC-1001) was synthesized for breast cancer imaging. In vitro cellular uptake studies were performed in the breast cancer MCF-7 and noncancerous breast epithelial MCF-10A cell lines to establish tumor specificity. In vivo time-dependent fluorescence and PET imaging of breast tumor xenografts in mice were performed. Blood clearance, biodistribution, and tumor-specific uptake and plasma binding of PC-1001 were quantified. Tumor histology (H&E staining) and fluorescence imaging were examined.ResultsPC-1001 displayed similar fluorescence properties (ε = 82,880 cm^? 1 M^? 1, E_x/E_m = 750/820 nm) to the parental dye. Time-dependent cellular accumulation indicated significantly higher probe uptake (> 2-fold, 30 min) in MCF-7 than MCF-10A cells and the uptake was observed to be mediated by organic anion transport peptides (OATPs) system. In vivo studies revealed that PC-1001 has desirable accumulation profile in tumor tissues, with tumor versus muscle uptake of about 4.3 fold at 24 h and 5.8 fold at 48 h post probe injections. Blood half-life of PC-1001 was observed to be 4.3 ± 0.2 h. Microscopic fluorescence imaging of harvested tumor indicated that the uptake of PC-1001 was restricted to viable rather than necrotic tumor cells.ConclusionsA highly efficient tumor-targeting PET/fluorescence imaging probe PC-1001 is synthesized and validated in vitro in MCF-7 breast cancer cells and in vivo in mice breast cancer xenograft model.     

Skin fluorescence following photodynamic therapy with NPe6 photosensitizer

BackgroundThe second-generation photosensitizer NPe6 has strong anti-tumor effects with a much shorter photosensitive period than the first-generation photosensitizer Photofrin. Although photosensitive period has been reduced, skin photosensitivity is still a major side effect of photodynamic therapy (PDT). Therefore, we conducted a prospective study to investigate whether the NPe6 fluorescence intensity in skin after PDT could be measured effectively in human patients to improve the management of a patient's photosensitive period.MethodsThe NPe6 fluorescence measurements using a constructed fluorescence sensing system at the inside of the arm were acquired prior to and 5 and 10 min after NPe6 administration as well as at the time of PDT (4–5 h after administration), at discharge (2 or 3 days after PDT), and at 1 or 2 weeks after PDT. Participants were interviewed as to whether they had any complications at 2 weeks after PDT.ResultsNine male patients and one female patient entered this study. Nine patients were inpatients and one patient was an outpatient. All of the measurements of NPe6 fluorescence in the skin could be obtained without any complications. The spectral peak was detected at the time of discharge (2–3 days after administration) in most cases and it decreased at 1 or 2 weeks after PDT.ConclusionsThe fluorescence of NPe6 in the skin could be detected feasibly using the fluorescence sensing system in human patients. Measuring the relative concentration of NPe6 in the skin indirectly by measuring fluorescence intensity might be useful to predict the period of skin photosensitivity after PDT.     

Physiological considerations acting on triplet oxygen for explicit dosimetry in photodynamic therapy

The aims of this study were to determine the spatial and temporal theoretical distribution of the concentrations of Protoporphyrin IX, ³O₂ and doses of ¹O₂. The type II mechanism and explicit dosimetry in photodynamic therapy were used. Furthermore, the mechanism of respiration and cellular metabolism acting on ³O₂ were taken into account. The dermis was considered as an absorbing and a scattering medium. An analytical solution was used for light diffusion in the skin. The photophysical, photochemical and biological effects caused by PDT with the initial irradiances of 20, 60 and 150 mW/cm² were studied for a time of exposure of 20 min and a maximum depth of 0.5 cm. We found that the initial irradiance triples its value in 0.02 cm and that almost 100% of PpIX is part of the dynamics of reactions in photodynamic therapy. Additionally, with about 40 μM of ³O₂ there is a balance between the consumed and supplied oxygen. Finally, we determined that with 60 mW/cm², the highest dose of ¹O₂ is obtained.     

Simultaneous detection of As and Se in polyester resin skin phantoms

It is known that As and Se act as metabolic antagonists. Hence, an improvement in assessing As-related health risks can be achieved by simultaneous quantitative measurements of both As and Se levels in the human body. In this paper, the simultaneous detection of trace concentrations of As and Se in polyester resin skin phantoms was demonstrated. The experiments were performed with a commercial miniature X-ray tube and silicon PiN detector X-ray fluorescence (XRF) system. No significant overlap between the K_α peaks of the two elements was observed. Minimum detection limits of (1.05±0.02) μg As g^?1 and (0.88±0.02) μg Se g^?1 were found.     

Thermoluminescent characterization of HfO2:Tb3+ synthesized by hydrothermal route

Thermo and photoluminescent properties of nanoparticles (NPs) of hafnium oxide (HfO₂), both intrinsic and doped with terbium (Tb³⁺) are reported. The NPs of HfO₂ were synthesized by hydrothermal route, using hafnium tetrachloride (HfCl₄) and terbium chloride hexahydrated (TbCl₃∙6H₂O) as precursors and sodium hydroxide (NaOH) to adjust the pH. Deionized water was used as solvent in all cases. The synthesis was carried out at different dopant concentrations from 0 to 20 at% of terbium with respect to the amount of hafnium in the precursor solution. The temperature of hydrothermal treatment was 200 °C and 80 min of reaction time. X-ray diffraction results show that at terbium concentrations higher than 15 at% the HfO₂ nanoparticles have a crystalline structure corresponding to the tetragonal phase. Thermoluminescent (TL) characterization was performed after 5 min irradiation of the samples with ultraviolet light of 200 nm wavelength. The highest TL emission was observed on samples with 7 at% of Tb, with the TL peak centered at 128 °C. Thermoluminescence analysis shows behavior associated with second-order kinetics with activation energy of 0.49 eV. Photoluminescent spectrum present the characteristics ⁵D₄→⁷FJ (J=3–6) terbium ion electronic transitions lines centered on 489 nm, 543 nm, 584 nm and 622 nm.     

Decreased skin temperature of the foot increases gait variability in healthy young adults

We investigated the effects of reduction in plantar skin temperature on gait. Thirty-four healthy subjects (20 men and 14 women; mean age 22.2 ± 2.5 years; mean height 166.8 ± 8.3 cm) walked 16 m under two different conditions – normal conditions (NC) with the skin at a basal temperature, and cold conditions (CC) after cooling of the plantar skin to about 15 °C. Wireless motion-recording sensor units were placed on the back at the level of L3 and on both heels to measure acceleration and angular velocity. Gait velocity and mean stride, stance and swing times were calculated. The variability of lower limb movement was represented by the coefficients of variation (CVs) of stride, stance and swing times, and that of trunk movement was represented by autocorrelation coefficients (ACs) in three directions (vertical: VT; mediolateral: ML; and anteroposterior: AP). Gait velocity was significantly lower under CC conditions than under NC (p < 0.0001). None of the temporal parameters were changed by plantar cooling. However, all parameters of gait variability were significantly worse under CC, and AC-VT, AC-ML, and AC-AP were significantly lower under CC than under NC, even after adjusting for gait velocity (p = 0.0005, 0.0071, and 0.0126, respectively). Our results suggest that reducing plantar skin temperature induces gait variability among healthy young adults. Further studies are now needed to explore the relationship between plantar skin temperature and gait in the elderly.     

A comparison of the antibacterial activity of the two methods of photodynamic therapy (using diode laser 810 nm and LED lamp 630 nm) against Enterococcus faecalis in extracted human anterior teeth

BackgroundFailure of endodontic treatment is usually due to an inadequate disinfection of the root canal system. Enterococcus faecalis has been widely used as a valuable microbiological marker for in-vitro studies because of its ability to colonize in a biofilm like style in root canals, invading dentinal tubules and resistance to some endodontic treatments.The aim of this study was to investigate the antibacterial effects of two methods of photodynamic therapy using a light emitting diode lamp (LED lamp, 630 nm) and a diode laser (810 nm) on E. faecalis biofilms in anterior extracted human teeth.MethodsFifty six single-rooted extracted teeth were used in this study. After routine root canal cleansing, shaping and sterilization, the teeth were incubated with E. faecalis for a period of two weeks. Teeth were then divided into two experimental groups (nu = 23) and two control groups (nu = 5). Teeth in one experimental group were exposed to a diode laser (810 nm), and in the other group samples were exposed to a LED lamp (630 nm). Intracanal bacterial sampling was done, and bacterial survival rate was then evaluated for each group.ResultsThe Colony Forming Unit (CFU) in LED group (log 10 CFUs = 4.88 ± 0.82) was significantly lower than the laser group (log CFUs = 5.49 ± 0.71) (p value = 0.021). CFUs in positive control group (Log 10 CFUs = 10.96 ± 0.44) were significantly higher than the treatment group (p ˂ 0.001). No bacterial colony was found in negative control group.ConclusionThe results of this research show that photodynamic therapy could be an effective supplement in root canal disinfection. PDT using LED lamp was more effective than diode laser 810 nm in reducing CFUs of E. faecalis in human teeth.