Efficacy of three different laser wavelengths for in vitro wound healing

Background and objective: Despite contradictory reports on the effect of laser light on cell proliferation, studies have shown that appropriate doses and wavelengths of laser light are therapeutically beneficial in tissue repair and pain control. This study aimed to establish if the dose and/or wavelength influenced the biological responses of irradiated in vitro fibroblasts – 1 h after laser irradiation.
Materials and methods: This study aimed to establish cellular responses of normal and wounded human skin fibroblasts to helium-neon (632.8 nm), diode (830 nm) and Nd:YAG (1064 nm) laser irradiation using one exposure of 5 or 16 J/cm² on day 1 and again on day 4.
Results: Wounded cells exposed to 5 J/cm² using 632.8 nm showed an increase in cell migration and haptotaxis, a stable increase in the release of interleukin-6 (IL-6), a decrease in caspase 3/7 activity, an increase in ATP viability and an increase in cell proliferation – 1 h after the final exposure. The results confirm that changes in parameters such as ATP viability, cytokine expression (IL-6), cell proliferation (alkaline phosphatase enzyme activity) and DNA damage can be observed directly after the laser irradiation. The amount of DNA damage and cytotoxicity may be related to duration of the laser irradiation, which is dependent on the power density (mW/cm²) of each laser.
Conclusion: The results indicate that 5 J/cm² using 632.8 nm results in a stimulatory effect that is more effective than 830 and 1064 nm. The results suggest possible mechanisms by which the wavelength may potentially influence the cellular responses of wounded cells.     

Investigation of basal cell carcionoma by confocal laser scanning microscopy in vivo

Background/purpose In vivo confocal laser scanning microscopy (CLSM) allows to study human skin up to 200 µm deep non-invasively. Aim of this study was to investigate basal cell carcinoma (BCC) using in vivo CLSM, and to compare the micromorphologic features of BCC with uninvolved skin.
Methods Twelve patients with histological diagnosis of BCC referred to our department for tumor excision were investigated on the lesion(s) and on clinically uninvolved sites preoperatively by in vivo CLSM using the Vivascope 1000 (Lucid Inc., Rochester, USA). The images were compared to histological examinations of the excised tissue.
Results Typical changes in vasculature such as increase in number and diameter of the blood vessels, loss of the vascular architecture, parallelly and horizontally orientated vessels, and accumulation and rolling phenomena of bright reflecting cells of 11.88 ± 1.75 µm in diameter along the vessel wall were observed in all BCCs. The tumor stroma of the BCCs showed a strong reflectance mainly due to numerous bundles of collagen fibers encoating dark, cell-rich areas of tumor parenchym. In five patients, slim basaloid cells with relatively large, elongated dark nuclei were observed in the periphery of the tumor parenchym. In the fibrosing type of BCC, curled bundles of collagen with large cells represented the tumor stroma.
Conclusions BCC can be investigated by CLSM and provide typical features. Besides the tumor parenchym and stroma, typical changes in vasculature seem to be a sensitive criteria for BCC and may in future help in diagnosing BCC by CLSM as well as in assessing the margins of large tumors. We suggest that CLSM is a promising non-invasive tool for the diagnostics of BCC and the assessment of tumor margins prior to surgery.     

In vivo confocal laser scanning microscopy for non-invasive diagnosis of pemphigus foliaceus

Background/purpose: In vivo confocal laser scanning microscopy (CLSM) is a modern non-invasive method for investigation of the skin that allows real-time visualization of individual cells and sub-cellular structures at resolution similar to the one provided by routine histopathology. Our aim was to investigate the potential of CLSM for non-invasive diagnosis of pemphigus foliaceus (PF).
Methods: Pre-existing and mechanically induced lesions in two cases of PF were examined by means of CLSM, parallel to routine histology, direct immunofluorescence microscopy and enzyme-linked immunosorbent assay performed in the same patients.
Results: The morphological features characteristic for PF, namely an intraepidermal blister with acantholytic cells in the blister cavity, were readily detectable by means of CLSM. The findings were consistent in both patients and across the investigated lesions. The confocal images were consistent with the routine histology of the pre-existing lesions. No differences in the confocal images of pre-existing lesions compared with mechanically induced ones were observed.
Conclusions: Our findings suggest the potential of CLSM as a non-invasive tool for the diagnosis of pemphigus and differentiation of its subtype. Although at present the method cannot replace the current diagnostic standards for pemphigus, it may be successfully used as in vivo non-invasive screening tool to facilitate the diagnosis and point to the need for further investigation of the patient.     

Correlation of image analysis features and visual morphology in melanocytic skin tumours using in vivo confocal laser scanning microscopy

Background/purpose: In vivo confocal laser scanning microscopy (CLSM) represents a novel imaging tool that allows the non-invasive examination of skin cancer morphology at a quasi histological resolution without biopsy. Previous studies dealt with the search for diagnostic, but subjective visual criteria. In this study we examined the correlation between objectively reproducible image-analysis features und visual morphology in melanocytic skin tumours using CLSM.
Methods: Eight hundred and fifty-seven CLSM tumour images including 408 benign nevi and 449 melanoma images were evaluated. Image analysis was based on features of the wavelet transform and classification tree analysis (CART) was used for classification purposes. In a second step, morphologic details of CLSM images, which have turned out to be of diagnostic significance by the classification algorithm were evaluated.
Results: CART analysis of the whole set of CLSM images correctly classified 97.55% of all melanoma images and 96.32% of all nevi images. Seven classification tree nodes seemed to indicate benign nevi, whereas six nodes were suggestive for melanoma morphology. The visual examination of selected nodes demonstrated that monomorphic melanocytic cells and melanocytic cell nests are characteristic for benign nevi whereas polymorphic melanocytic cells, disarray of melanocytic architecture and poorly defined or absent keratinocyte cell borders are characteristic for melanoma.
Conclusion: Well-known, but subjective CLSM criteria could be objectively reproduced by image analysis features and classification tree analysis. Moreover, features not accessible to the human eye seem to contribute to classification success.     

Visualizing nuclei in skin cryosections: viable options to 4'6-diamidino-2-phenylindol for confocal laser microscopy

Background: Visualization of nuclei in skin (cryo‐) sections is essential for both, rapid overview and reliable orientation within skin samples. Therefore, nuclear staining is a very common counterstain for immunohistochemical studies of human skin as this nuclear staining precisely depicts the cellular distribution within the epidermis. Moreover, it clearly shows the epidermal–dermal border as well as the transition zone between the living and the cornified layers of the epidermis. For standard epifluorescence microscopy, 4′6‐diamidino‐2‐phenylindol (DAPI) is commonly used. For confocal laser scanning microscopy (CLSM), however, DAPI is often not suitable because its excitation maximum is in the ultraviolet (UV) range (Ex_max 359 nm) when bound to DNA, and UV lasers and the corresponding optics are not part of CLSM standard configuration. Methods: In order to find an adequate DAPI substitute that is excitable with standard visible light lasers, the following nuclear stains were tested: LOLO^?‐1 iodide (Ex_max 565 nm), TOTO^®‐3 iodide (Ex_max 642 nm), LO‐PRO^?‐1 iodide (Ex_max 567 nm), SYTO^® 84 (Ex_max 567 nm), SYTO^® 85 (Ex_max 567 nm), SYTOX^® Green (Ex_max 488 nm) and SYTOX^® Orange (Ex_max 547 nm), Propidium iodide (Ex_max 535 nm). Besides optimal concentration and incubation time, following criteria were also evaluated: photobleaching, background, e.g. cytoplasmic staining of RNA, and sensitivity to different fixation conditions (unfixed, IEM fixation, PLP fixation and PFA fixation). Results: According to these criteria Sytox^® Green showed the best overall staining score and can be used for variously fixed skin samples and shows a distinct and stable green nuclear fluorescence.     

In vivo imaging of intradermal tattoos by confocal scanning laser microscopy

BACKGROUND/AIMS: In vivo confocal laser scanning microscopy (CLSM) is a new method for high-resolution imaging of intact skin in situ. Horizontal mapping of the outer skin is provided (magnification x 1000). OBJECTIVES: Tattooing is popular all over the world; however, tattooed skin has not been studied in using CLSM. RESULTS: Tattoos in two volunteers were studied using the Vivascope1500 of Lucid Inc. Subepidermal massive deposits of dense, clustered pigment granules up to about 3 mum in size corresponding to black tattoos, and more scarce and diffuse deposits, corresponding to red, blue and green tattoos, were observed. Diffuse pigment granules tended to accumulate in the outer dermis underneath the level of the basement membrane zone. CONCLUSIONS: Dermal pigments from tattoos can be imaged in vivo using CLSM. This application of CLSM has an important future potential for pre-evaluation of tattoos before laser removal, predicting good or poor outcome of laser removal.     

Seborrheic keratosis or verruca plana? A pilot study with confocal laser scanning microscopy

Background: Differentiation of some seborrheic keratosis (SK) and verruca plana (VP) lesions is a challenge. Confocal laser scanning microscopy (CLSM) has been proved to be useful in the diagnosis of skin diseases; however, to date, there is no report on the differential study of the two diseases with CLSM. Objectives: To obtain the CLSM image characteristics of SK and VP, and then test the differential ability of CLSM imaging. Methods: We recruited 10 patients with typical lesions of SK under CLSM images to validate the features reported. Another 10 patients with typical VP lesions were also recruited, imaged with CLSM and biopsied to obtain the features under CLSM images based on histology analysis. Then, we attempt to summarize and refine those characteristics collected to obtain the most significant ones. All the cases with lesions suggestive of SK or VP were advised to undergo imaging with CLSM, and if CLSM imaging reflected discordantly with the clinical diagnosis, a biopsy was suggested for the exact lesion imaged. Those cases with CLSM and histology results were collected. Finally, two clinical dermatologists, who had no previous experience with CLSM, were tested with the simplified features of CLSM images to differentiate the suspected lesions of SK and VP among the cases collected. Results: In total, there were 58 cases with CLSM images and histology results collected, in which, 40 cases were diagnosed as SK and 18 cases as VP by histology. The two blinded dermatologists' judgments were identical to histology analysis. Conclusion: CLSM proved to be valuable in the differential diagnosis of SK and VP. The simplified characteristics were easily understood and acceptable to those with no previous experience of CLSM.     

Pilot study of dual-wavelength (532 and 633 nm) laser Doppler imaging and infrared thermography of morphoea

Background  Little is known about the pathophysiology of localized scleroderma (skin fibrosis, also termed 'morphoea'), although it is likely that microvascular dysfunction is a contributing factor.
Objectives  Our aim was to investigate different components of blood flow in morphoea using infrared thermography and dual-wavelength laser Doppler imaging (LDI).
Methods  Eight plaques of morphoea (in eight patients) were studied. Skin temperature and blood flow were assessed in both affected (within plaque) and adjacent unaffected (perilesional) skin.
Results  Skin temperature (representing blood flow) was higher in all areas of morphoea when compared with uninvolved skin. Perfusion within the plaques was found to be increased, when compared with uninvolved skin; in all cases as imaged by red wavelength (633 nm) LDI (representing blood flow through large, thermoregulatory vessels) and in six of eight cases by green wavelength (532 nm) LDI (representing nutritive capillary blood flow). The median (range) skin temperature difference between plaque and perilesional skin was 1·1 (0·7–2·2) °C and the median (range) ratios of plaque/perilesional perfusion as measured by red and green wavelength LDI were 1·3 (1·1–1·9) and 1·1 (0·8–1·5) arbitrary perfusion units, respectively.
Conclusions  Microvascular perfusion is increased within morphoea plaques and the increased response detected by both thermography and red wavelength LDI, as compared with green wavelength LDI, suggests that the increase in perfusion is more marked in deeper, larger, rather than in superficial, smaller vessels.     

Effects of near-infrared laser exposure in a cellular model of wound healing

Background: Clinical studies have demonstrated beneficial outcomes for low-level laser therapy (LLLT) using near-infrared (NIR) wavelengths. It has been hypothesized that the benefits of NIR LLLT are due in part to the thermal effects of NIR exposure. However, it is not clear whether photochemical interactions between NIR light and superficial tissues contribute to beneficial outcomes. To investigate the photochemical effects of NIR exposure, the efficacy of 980 nm NIR LLLT on human fibroblast growth rates is investigated using an in vitro model of wound healing.
Methods: A small pipette is used to induce a wound in fibroblast cell cultures, which are imaged at specific time intervals over 48 h and exposed to a range of laser doses (1.5–66 J/cm²) selected to encompass the range of doses used during other in vivo and in vitro studies. For each image acquired, wound sizes were quantified using a novel application of existing image processing algorithms.
Results: Cell growth rates were compared across different laser exposure intensities with the same exposure duration, and across different laser exposure durations with the same exposure intensity. Exposure to low- and medium-intensity laser light accelerates cell growth, whereas high-intensity light negated the beneficial effects of laser exposure. Cell growth was accelerated over a wide range of exposure durations using medium-intensity laser light, with no significant inhibition of cell growth at the longest exposure durations used in this study.
Conclusion: Low-level exposure to 980 nm laser light can accelerate wound healing in vitro without measurable temperature increases. However, these results also demonstrate the need for appropriate supervision of laser therapy sessions to prevent overexposure to NIR laser light that may inhibit cell growth rates observed in response to lower intensity laser exposure.     

应用共聚焦激光扫描显微镜对白癜风成像的观察与研究

目的应用共聚焦激光扫描显微镜观察白癜风皮损及周边皮肤图像特征。方法对46例白癜风患者69处皮损及周边皮肤进行共聚焦激光扫描显微镜检测,获得白癜风皮损特征性图像。结果皮损周边皮肤图像显示棘细胞层下部和基底层的角质细胞因含有黑素呈明亮的"圆形"或"椭圆形"色素环,皮损处图像显示色素环的数量及亮度呈不同程度减少或消失。结论共聚焦激光扫描显微镜是一项新的无创性皮肤影像技术,具有在体、实时、动态三维计算机断层成像的特点,可以直接观察到白癜风患者皮损处及周边角化细胞内黑素的形态变化,可为临床提供客观的评估依据。     

Fluorescence confocal laser scanning microscopy for in vivo imaging of epidermal reactions to two experimental irritants

Background: Fibre‐optic fluorescence confocal laser scanning microscopy (CLSM) is a novel non‐invasive technique for in vivo imaging of skin. The cellular structure of the epidermis can be studied. A fluorophore, e.g. fluorescein sodium, is introduced by an intradermal injection or applied to the skin surface before scanning. Images are horizontal optical sections parallel to the skin surface. Fluorescence CLSM has hitherto not been applied to experimental contact dermatitis. Objective: The aim was to study the applicability of fluorescence CLSM for in situ imaging of irritant contact dermatitis reactions caused by established model irritants, e.g. sodium lauryl sulphate (SLS) and pelargonic acid (PA). Methods: Twelve healthy individuals volunteered. The flexor aspect of the right and the left forearm was exposed to SLS in water and PA in isopropanol and occluded under Finn Chambers for 24 h. The reactions were rated clinically and, following epicutaneous and intra‐dermal application of fluorescein sodium, studied by fluorescence CLSM, magnification × 1000. Results: Both irritants disturbed the epidermal intercellular borders, which became blurred, thickened and variably altered. This was interpreted as being a result of chemical damage to cellular membranes. Cell borders might show a double contour as a result of inter‐cellular oedema. PA might increase the size of individual keratinocytes interpreted as a result of intra‐cellular disturbance with oedema. SLS‐exposed sites showed clusters of keratinocytes with visible nuclei in the outer layers of the epidermis, e.g. a parakeratotic shift supposed to be due to increased cell proliferation elicited by SLS. The isopropanol vehicle and PA did not interfere with the CLSM imaging technique or the experimental procedures. SLS, being a detergent, however, modified the physico‐chemical properties of the skin surface and both disturbed epicutaneous labelling with the flurophore and immersion oil coupling between the skin surface and the optical system. Thus, SLS was technically more difficult to study by CLSM than PA. Conclusions: This preliminary study demonstrated the applicability of fluorescence CLSM for a detailed study of experimental skin irritants in vivo. Essential findings were disturbed and widened cell borders, swelling of keratinocytes by PA and induction of a parakeratotic shift by SLS with clusters of keratinocytes holding nuclei in the epidermis. Fluorescence CLSM offers a unique opportunity to study the inter‐ and intracellular water compartments directly in the epidermis in situ and an opportunity to visualize cell proliferation manifested as parakeratosis. Fibre‐optic fluorescence CLSM of irritant reactions is, however, technically more complicated than reflectance CLSM and may not be applicable to any irritant. SLS applied epicutaneously interacted with the skin surface and coupling to the microscope and was thus found to be more difficult to study technically than PA. PA dissolved in isopropanol is for technical reasons, and with SLS as alternative, considered the preferred model irritant.     

Diagnosis of cutaneous tumors with in vivo confocal laser scanning microscopy

In recent years, in vivo confocal laser scanning microscopy (CLSM) has become an established method for the non‐invasive examination of the skin. In vivo CLSM allows for real‐time imaging of micro‐anatomic cutaneous structures. It has been used to diagnose ambiguous skin tumors and to measure subclinical tumor spread prior to surgery. By additionally providing high power morphologic information, in vivo CLSM helps to reduce unnecessary biopsies. A multitude of diagnostic features for skin tumors has been published. Here we review published diagnostic in vivo CLSM features, and compare them to our own experience in 100 tumors. In combination with clinical examination and dermatoscopy, in vivo CLSM is a valuable additional tool for non‐invasive skin tumor diagnosis.     

Skin reflectance-spectra and colour-value dependency on measuring-head aperture area in ordinary reflectance spectrophotometry and tristimulus colourimetry

Background/aims:   Measurement of skin colour has become increasingly popular in the study of dermatology with the increased availability of portable instruments. However, different instruments have been reported as giving different results from measurement of the same skin region. The aim of this study was to examine the effects of differences in measuring-head aperture area on skin reflectance spectra and colour values.
Methods:   We measured both reflectance spectra and CIE-L*a*b* values of the skin in five different anatomical regions on 10 subjects using two MINOLTA reflectance spectrometers that were identical apart from the aperture area of the measuring heads (diameters: 5 and 11 mm). For comparison, data were also obtained from a skin-coloured tile.
Results:   Skin reflectance values measured with the wider-aperture instrument were higher than those measured with the other, irrespective of anatomical location. The differences between the two were near zero at an incident light wavelength of 400 nm, but increased to around 10% of the reflectance value at 700 nm, increasing exponentially with incident light of increasing wavelength. Skin colour was observed to be brighter, redder and yellower, in CIE-L*a*b* expression, when measured with the wider-aperture instrument. The differences between measurements obtained from the skin-coloured tile were much smaller.
Conclusion:   Skin reflectance and colour values measured with reflectance instruments are not absolute data but depend on the aperture area of the measuring head. This is probably due to variations in the proportion of longer-wavelength light reflected from the skin and collected by the instrument.     

Confocal laser scanning microscopic observation of glycocalyx production by Staphylococcus aureus in skin lesions of bullous impetigo,atopic dermatitis and pemphigus foliaceus

BACKGROUND: Glycocalyx collapses during dehydration to produce electron-dense accretions. Confocal laser scanning microscopy (CLSM) may be used to visualize fully hydrated microbial biofilms. OBJECTIVES: Using CLSM, to analyse glycocalyx production by Staphylococcus aureus cells in skin lesions of bullous impetigo, atopic dermatitis and pemphigus foliaceus. A second objective was to compare numbers of S. aureus cells in tissue sections prepared by different methods for routine light microscopy. METHODS: S. aureus cells in skin lesions of impetigo, atopic dermatitis and pemphigus were stained with safranin, and positive staining with fluorescein isothiocyanate-conjugated concanavalin A was considered to indicate the presence of glycocalyx. RESULTS: All S. aureus cells tested in skin lesions of impetigo, atopic dermatitis and pemphigus were covered with glycocalyx and formed microcolonies. The numbers of S. aureus cells in a routine light microscopy section were significantly lower than those in a frozen section that had not been dehydrated with ethanol. CONCLUSIONS: S. aureus cells generally produce glycocalyx in skin lesions of bullous impetigo, atopic dermatitis and pemphigus foliaceus, which accounts for the difficulty of removing S. aureus cells from these skin lesions. The glycocalyx may collapse during dehydration and most of the S. aureus cells may be carried away during preparation of routine light microscope sections.     

Diagnostic image analysis of malignant melanoma in in vivo confocal laser-scanning microscopy: a preliminary study

Background/purpose: In this study we assessed the applicability of image analysis and a machine learning algorithm on diagnostic discrimination of benign and malignant melanocytic skin tumours in in vivo confocal laser-scanning microscopy (CLSM).
Methods: A total of 857 CLSM tumour images including 408 benign nevi and 449 melanoma images was evaluated. Image analysis was based on features of the wavelet transform. For classification purposes we used a classification tree software (CART). Moreover, automated image analysis results were compared with the prediction success of an independent human observer.
Results: CART analysis of the whole set of CLSM tumour images correctly classified 97.55% and 96.32% of melanoma and nevi images. In contrast, sensitivity and specificity of 85.52% and 80.15% could be reached by the human observer. When the image set was randomly divided into a learning (67% of the images) and a test set (33% of the images), overall 97.31% and 81.03% of the tumour images in the learning and test set could be classified correctly by the CART procedure.
Conclusion: Provided automated decisions can be used as a second opinion. This can be valuable in assisting diagnostic decisions in this new and exciting imaging technique.     

Spectral fluorescence lifetime detection and selective melanin imaging by multiphoton laser tomography for melanoma diagnosis

Abstract:  Multiphoton excited tissue fluorescence summarises the emission of all naturally occurring endogenous fluorescent bio-molecules with their often overlapping fluorescence spectra. Common fluorescence intensity measurements could not be utilised to distinguish between different fluorophores or metabolic states. To overcome this limitation, we investigated new procedures of selective melanin imaging and spectral fluorescence lifetime imaging in combination with high resolution multiphoton laser tomography. Overall 46 melanocytic lesions of human skin were analysed. We suggested that fluorescence light, detected in such a way, may yield additional information for melanoma diagnostics. Remarkable differences in lifetime behaviour of keratinocytes in contrast to melanocytes were observed. Fluorescence lifetime distribution was found in correlation with the intracellular amount of melanin. Spectral analysis of melanoma revealed a main fluorescence peak around 470 nm in combination with an additional peak close to 550 nm throughout all epidermal layers. Excitation at 800 nm shows a selectively observable fluorescence of melanin containing cells and offers the possibility of cell classification. Procedures of selective imaging as well as spectral fluorescence lifetime imaging by means of multiphoton laser tomography support diagnostic decisions and may improve the process of non-invasive early detection of melanoma.     

Melanoma or pigmented basal cell carcinoma: a clinical-pathologic correlation with dermoscopy, in vivo confocal scanning laser microscopy, and routine histology

Background/purpose: New techniques are being explored for improving diagnostic accuracy of pigmented skin lesions. Confocal scanning laser microscopy (CSLM) may represent such a novel technique. The purpose of this report was to demonstrate the potential application of CSLM as an aid in the diagnosis of a pigmented skin lesion that is clinically suspicious for melanoma.
Methods: An irregular pigmented lesion was examined clinically and dermoscopically. The lesion was imaged by CSLM and subsequently excised for histologic examination. Findings from CSLM were correlated with features observed on the dermoscopic and histologic examination.
Results: Confocal scanning laser microscopy (CSLM) allowed for the non-invasive visualization of the histologic features of superficial pigmented BCC, including buds and "islands" of tumor cells at the dermoepidermal junction and melanin-laden macrophages. Conventional histology confirmed the diagnosis of pigmented BCC.
Conclusion: Confocal scanning laser microscopy (CSLM) may serve as an aid in the non-invasive diagnosis of pigmented skin lesions clinically suspicious for melanoma.     

Age related changes of human skin investigated with histometric measurements by confocal laser scanning microscopy in vivo

Background/aims: The confocal laser scanning microscope Vivascope (Lucid, Henrietta) allows skin to be studied in real-time with a resolution of 0.5 µm horizontal and 1.3 µm vertical in vivo. In this study, we present the results of a comparison between the skin of an older and a younger group of volunteers by in vivo histometric measurements.
Methods: To investigate changes caused by age, 13 young (18–25 years) and 13 older (> 65 years) volunteers were examined. The following parameters were measured using the Vivascope at the volar forearm: minimal thickness of the epidermis (E_min), size of cells in the granular layer (A_gran), thickness of the horny layer (DSC), thickness of the basal layer (DSB) and number of dermal papillae per area (PapI). The image analysis program image tool was used to measure the size of the cells and the thickness of the basal layer.
Results: The older group of volunteers showed a significant increase in E_min, no significant change in DSC, a significant decrease in dermal papillae and in the thickness of the basal layer, and an increase in A_gran compared to the younger group.
Conclusions: Histometric measurements by in vivo confocal laser scanning microscopy are a sensitive and non-invasive tool for characterizing and quantifying histological changes of the epidermis and papillary dermis due to ageing.     

激光疗法在雄激素性脱发中的应用

近年来,国内外研究表明光疗法治疗雄激素性脱发效果良好。波长650~785 nm的低能量光、波长1550 nm和1927 nm的非剥脱性点阵激光以及剥脱性二氧化碳点阵激光治疗雄激素性脱发有效,其中,655 nm激光的疗效证据最充分。本文对不同波长的低能量激光和高能量点阵激光在雄激素性脱发治疗中的应用进行综述。     

Fluorescence lifetime imaging distinguishes basal cell carcinoma from surrounding uninvolved skin

Background  Fluorescence lifetime imaging (FLIM) is a novel imaging technique that generates image contrast between different states of tissue due to differences in fluorescence decay rates.
Objectives  To establish whether FLIM of skin autofluorescence can provide useful contrast between basal cell carcinomas (BCCs) and surrounding uninvolved skin.
Methods  Unstained excision biopsies of 25 BCCs were imaged en face with FLIM following excitation of autofluorescence with a 355 nm pulsed ultraviolet laser.
Results  Using FLIM we were able to distinguish areas of BCC from surrounding skin in an ex vivo study. Significant reductions in mean fluorescence lifetimes between areas of BCC and areas of surrounding uninvolved skin were demonstrated ( P  <   0·0001). These differences were apparent irrespective of the decay model used to calculate the fluorescence lifetimes (single vs. stretched exponential) or the long-pass filter through which the emitted autofluorescence was collected (375 vs. 455 nm). Conversely, there was no significant difference between the BCC and uninvolved areas of each sample when mean autofluorescence intensities were examined. Moreover, wide-field false-colour images of fluorescence lifetimes clearly discriminated areas of BCC from the surrounding uninvolved skin.
Conclusions  We therefore believe that FLIM has a potential future clinical role in imaging BCCs for rapid and noninvasive tumour delineation and as an aid to determine adequate excision margins with best preservation of normal tissue.