The relationship between habitual physical activity and skin mechanical properties.

BACKGROUND: Physical activity (PA) is important for body health. A few reports suggested that PA also influenced skin structure and components. Little data are available on the influence of PA on skin mechanical properties (SMP). Here, we investigated the relationship between PA and SMP. METHODS: Twenty-five healthy Japanese female subjects (31.0 ± 3.3 years) were enrolled in the study. To monitor the 24-hr pulse rate, a wrist watch-type pulse monitor was used. PA intensity was divided into five PA intensity zones (max, anaerobic, aerobic, fat combustion, and warm-up) by the pulse monitor. The average values of the time spent on each intensity for 70 days were calculated. To measure SMP, a Cutometer was used at the end of the monitoring. R0 indicated the height of the maximal skin deformation, and R6 was the ratio between viscoelastic and elastic deformation. RESULTS: R0 was positively correlated with the time spent in four of the five PA intensity zones (max, anaerobic, aerobic, and fat combustion), whereas R6 was negatively correlated with the time spent in these four PA intensity zones. The time of warm-up did not correlate with SMP. CONCLUSION: These results suggest that habitual moderate-to-vigorous PA influences SMP.

Depth-resolved investigation of multiple optical properties and wrinkle morphology in eye-corner areas with multi-contrast Jones matrix optical coherence tomography.

BACKGROUND: Multi-contrast Jones matrix optical coherence tomography (JM-OCT) can provide quantitative depth-resolved local optical properties by improving the measurement algorithm. MATERIALS AND METHODS: We examined the relationship between depth-resolved local optical properties of eye-corner skin measured by JM-OCT and corresponding wrinkle morphology of aged women (n = 21; age range, 71.7 ± 1.7 years). Wrinkle morphology was analyzed by measuring the surface topography of three-dimensional replicas. The same regions were measured three-dimensionally by JM-OCT, and the local optical properties at each depth were computed. RESULTS: Birefringence (BR) and mean wrinkle depth correlated significantly at a depth of 88.2-138.6 µm from the skin surface, and attenuation coefficient (AC) and mean wrinkle depth correlated significantly at a depth of 12.6-18.9 µm and 189-459.9 µm from the skin surface, although a degree of polarization uniformity (DOPU) did not. Stepwise multiple regression analysis demonstrated that a significant regression equation (R2  = 0.649, P < .001) for predicting mean wrinkle depth was determined by BR at 107.1 µm depth (BR 107.1 µm ), DOPU at 170.1 µm (DOPU 170.1µm ), and AC at 252 µm (AC 252 µm ) as independent variables and that these standardized beta regression coefficients were -0.860, -0.593, and -0.440, respectively, suggesting that BR, DOPU, and AC sufficiently explained mean wrinkle depth. CONCLUSION: These results suggest that BR 107.1 µm , DOPU 170.1 µm, and AC 252 µm may indicate collagen-related structure in the papillary, upper-reticular dermis, and microstructure or tissue density in reticular dermis, respectively, and may be involved in wrinkle formation.

Useful parameters for the motion analysis of facial skin care in Japanese women.

BACKGROUND: Facial skin care (FSC) is an important routine for Japanese women. Hand motions during FSC physically affect psychological state. However, it is very difficult to evaluate hand motions during personal and complex FSC. The objective of this study was to find out objective and quantitative parameters for hand motions during facial skin care (FSC). Women who enjoy and soothe during FSC (Enjoyment group (E group), n = 20) or not (non-enjoyment group (NE group), n = 19) were recruited by an advance questionnaire. The same lotion, emulsion, and cream were provided to all subjects, and they used sequentially in the same way as the women's daily FSC. The motion of the marker on the back side of the right middle finger during FSC was tracked by a motion capture system. The heart rate variability (HRV) was also measured before and after FSC for evaluating psychological effect. RESULTS: The averaged acceleration (Avg. ACC), approximate entropy (ApEn), and power law scaling exponent (Rest γ) of the cumulative duration of slow motion from the sequential data of acceleration were evaluated. Compared to the NE group, the E group showed a lower Avg. ACC when using emulsion (p = 0.005) and cream (p = 0.007), a lower ApEn when using emulsion (p = 0.003), and a lower Rest γ (p = 0.024) when using all items, suggesting that compared to the NE group, the E group had more tender and regular motion, and sustainable slow motions, especially in the use of emulsion. In the E group, the low/high-frequency component of HRV decreased significantly after FSC, suggesting suppression of sympathetic activity (p = 0.045). NE group did not. For all subjects, ApEn and Rest γ showed significantly positive correlation with the increase in the low/high-frequency component of HRV after FSC (p < 0.01). ApEn showed significantly negative correlation with the increase in the high-frequency component of HRV after FSC (p < 0.05). Avg. ACC did not show significant correlation with them. These results suggested that the behavior of FSC influences the autonomic nerve system. CONCLUSIONS: ApEn and Rest γ are useful parameters for evaluating quality of hand motions during FSC.

HYBID (alias KIAA1199/CEMIP) and hyaluronan synthase coordinately regulate hyaluronan metabolism in histamine-stimulated skin fibroblasts.

The immune-regulatory compound histamine is involved in the metabolism of the essential skin component hyaluronan (HA). We previously reported that histamine up-regulates the expression of HYBID (hyaluronan-binding protein involved in hyaluronan depolymerization, also called CEMIP or KIAA1199), which plays a key role in HA degradation. However, no information is available about histamine's effects on HA synthase (HAS) expression, the molecular sizes of HA species produced, and histamine receptors and their signaling pathways in skin fibroblasts. Moreover, histamine's effects on photoaged skin remain elusive. Here, we show that histamine increases HA degradation by up-regulating HYBID and down-regulating HAS2 in human skin fibroblasts in a dose- and time-dependent manner and thereby decreases the total amounts and sizes of newly produced HA. Histamine H1 blocker abrogated the histamine effects on HYBID up-regulation, HAS2 suppression, and HA degradation. Histamine H1 agonist exhibited effects on HA levels, composition, and breakdown similar to those of histamine. Of note, blockade of protein kinase Cδ or PI3K-Akt signaling abolished histamine-mediated HYBID stimulation and HAS2 suppression, respectively. Immunohistochemical experiments revealed a significant ∼2-fold increase in tryptase-positive mast cells in photoaged skin, where HYBID and HAS2 expression levels were increased and decreased, respectively, compared with photoprotected skin. These results indicate that histamine controls HA metabolism by up-regulating HYBID and down-regulating HAS2 via distinct signaling pathways downstream of histamine receptor H1. They further suggest that histamine may contribute to photoaged skin damage by skewing HA metabolism toward degradation.

The influence of autogenic training on the physical properties of skin and cardiac autonomic activity in postmenopausal women: an exploratory study.

BACKGROUND: Autogenic training (AT) is a major relaxation training technique whose clinical efficacy has been verified in dermatology. Many reports demonstrate ameliorated skin conditions in AT-treated subjects with reduced psychological stress. However, no studies have examined the effects of AT on the skin of postmenopausal women. OBJECTIVES: We examine the influences of AT on the physical properties of skin and cardiac autonomic activity in postmenopausal women. METHODS: Postmenopausal women were classed into an AT group and a control one. The women in the AT group were mentored by a professional to practice AT twice a day for 7 weeks. The women in the control group were instructed to close their eyes for 3 minutes instead of AT. Hydration of the stratum corneum (SC), transepidermal water loss (TEWL), skin elasticity and heart-rate variability (HRV) were measured before and after the study period to examine how they changed. RESULTS: SC hydration and skin elasticity of the cheek, increased in both groups, and the increase was significantly higher in the AT group (n = 14) than in the control group (n = 12) (P < 0.05, Cohen's d = 1.03; P < 0.05, Cohen's d = 0.99; respectively). TEWL did not change in either group. LF/HF was lower in the AT group than in the control group (P < 0.05, Cohen's d = 0.91). CONCLUSION: AT increased SC hydration and skin elasticity with changes in the balance of autonomic nervous system activity in postmenopausal women, implying that AT may have improvement effects on aged skin by menopause.

Polarization-sensitive optical coherence elastography.

Polarization-sensitive optical coherence elastography (PS-OCE) is developed for improved tissue discrimination. It integrates Jones matrix-based PS-optical coherence tomography (PS-OCT) with compression OCE. The method simultaneously measures the OCT intensity, attenuation coefficient, birefringence, and microstructural deformation (MSD) induced by tissue compression. Ex vivo porcine aorta and esophagus tissues were investigated by PS-OCE and histological imaging. The tissue properties measured by PS-OCE are shown as cross-sectional images and a three-dimensional (3-D) depth-trajectory plot. In this trajectory plot, the average attenuation coefficient, birefringence, and MSD were computed at each depth, and the trajectory in the depth direction was plotted in a 3-D feature space of these three properties. The tissue boundaries in a histological image corresponded with the depth-trajectory inflection points. Histogram analysis and t-distributed stochastic neighbour embedding (t-SNE) visualization of the three tissue properties indicated that the PS-OCE measurements provide sufficient information to discriminate porcine esophagus tissues.

Gender- and age-related differences in facial sebaceous glands in Asian skin, as observed by non-invasive analysis using three-dimensional ultrasound microscopy.

BACKGROUND: While determining sebaceous gland morphology is useful in the treatment of skin disorders such as acne, a non-invasive assessment method has not been developed. Since age and gender affect sebum level, differences in sebaceous gland morphology according to these factors were investigated. METHODS: Facial skin was measured using a high-frequency three-dimensional ultrasound microscope. First, the ultrasound images were compared with skin sections. Next, we assessed sebaceous gland morphology. Images of sebaceous gland in the cheeks of young male, young female and elderly female subjects were obtained using ultrasound microscopy, and en face images were processed to measure the sebaceous gland area. RESULTS: In the ultrasound images, sebaceous glands and also thin collagen fibers, which surrounded the glands, could be detected as low-intensity regions. We called them sebaceous units. In young male subjects, the sebaceous unit areas 900-µm beneath the skin surface were larger than those at 700 µm. In contrast, depth-dependent differences in sebaceous unit area were not observed in young female subjects, indicating that males had cauliflower-shaped sebaceous glands while young females had somewhat more cylindrical and smaller sebaceous glands than the young males. Regarding age, the areas of sebaceous units at 900 µm were diminished and the depth of maximum area was shallower in elderly female subjects compared to young female subjects. Hence, sebaceous glands are considered to shrink with age. CONCLUSION: Differences in facial sebaceous unit morphology between genders as well as by age groups could be observed using high-frequency ultrasound microscopy.

Cartilage Oligomeric Matrix Protein Increases in Photodamaged Skin.

Cartilage oligomeric matrix protein (COMP) is a structural component of cartilage. Recent studies have described COMP as a pathogenic factor that promotes collagen deposition in fibrotic skin disorders such as scleroderma and keloid skin. Although collagen, a major dermis component, is thought to decrease in photoaged skin, recent reports have demonstrated the presence of tightly packed collagen fibrils with a structural resemblance to fibrosis in the papillary dermis of photoaged skin. Here we examined how photoaging damage relates to COMP expression and localization in photoaged skin. In situ hybridization revealed an increase in COMP-mRNA-positive cells with the progress of photoaging in preauricular skin (sun-exposed skin). The signal intensity of immunostaining for COMP increased with photoaging in not only the papillary dermis but also the reticular dermis affected by advancing solar elastosis. Immunoelectron microscopy detected the colocalization of COMP with both elastotic materials and collagen fibrils in photoaged skin. Ultraviolet light A irradiation of human dermal fibroblasts induced COMP expression at both the mRNA and protein levels. Ultraviolet light A-induced COMP expression was inhibited by an anti-transforming growth factor-ß antibody or SB431542, an activin receptor-like kinase 5 inhibitor. These results suggest that the transforming growth factor-ß-mediated upregulation of COMP expression may contribute to the modulation of dermal extracellular matrix in the photoaging process.

Regulation of Hyaluronan (HA) Metabolism Mediated by HYBID (Hyaluronan-binding Protein Involved in HA Depolymerization, KIAA1199) and HA Synthases in Growth Factor-stimulated Fibroblasts.

Regulation of hyaluronan (HA) synthesis and degradation is essential to maintenance of extracellular matrix homeostasis. We recently reported that HYBID (HYaluronan-Binding protein Involved in hyaluronan Depolymerization), also called KIAA1199, plays a key role in HA depolymerization in skin and arthritic synovial fibroblasts. However, regulation of HA metabolism mediated by HYBID and HA synthases (HASs) under stimulation with growth factors remains obscure. Here we report that TGF-ß1, basic FGF, EGF, and PDGF-BB commonly enhance total amount of HA in skin fibroblasts through up-regulation of HAS expression, but molecular size of newly produced HA is dependent on HYBID expression levels. Stimulation of HAS1/2 expression and suppression of HYBID expression by TGF-ß1 were abrogated by blockade of the MAPK and/or Smad signaling and the PI3K-Akt signaling, respectively. In normal human skin, expression of the TGF-ß1 receptors correlated positively with HAS2 expression and inversely with HYBID expression. On the other hand, TGF-ß1 up-regulated HAS1/2 expression but exerted only a slight suppressive effect on HYBID expression in synovial fibroblasts from the patients with osteoarthritis or rheumatoid arthritis, resulting in the production of lower molecular weight HA compared with normal skin and synovial fibroblasts. These data demonstrate that although TGF-ß1, basic FGF, EGF, and PDGF-BB enhance HA production in skin fibroblasts, TGF-ß1 most efficiently contributes to production of high molecular weight HA by HAS up-regulation and HYBID down-regulation and suggests that inefficient down-regulation of HYBID by TGF-ß1 in arthritic synovial fibroblasts may be linked to accumulation of depolymerized HA in synovial fluids in arthritis patients.

Sweat constitutes several natural moisturizing factors, lactate, urea, sodium, and potassium.

BACKGROUND: Amino acids (AAs) play important roles in maintaining an optimal hydration state of stratum corneum (SC) as a natural moisturizing factor (NMF). Recently, however, we have reported that lactate and potassium significantly affect the hydration state of SC. OBJECTIVE: To explore the source of lactate and potassium in SC, we compared the concentration of various NMFs such as AAs, pyrrolidone carbonic acid (PCA), lactate, sodium, and potassium in SC between anhidrotic and adjacent hidrotic areas of patients with acquired idiopathic generalized anhidrosis or segmental anhidrosis. METHODS: We examined 13 anhidrotic areas and the adjacent hidrotic skin of 10 different patients. We first determined anhidrotic and hidrotic areas of each patient by the iodine starch method and examined the hydration state of SC by measuring the high-frequency conductance. Then we obtained SC by tape stripping and measured the content of AAs, PCA, lactate, urea, sodium, and potassium in SC obtained from the anhidrotic and hidrotic areas. We examined the effect of increased insensible perspiration on the SC hydration and the concentrations of NMFs. RESULTS: The SC of anhidrotic areas showed significantly low hydration. Among NMFs, lactate, urea, sodium, and potassium were significantly decreased in the SC of anhidrotic areas, while AAs and PCA were not significantly different between hidrotic and anhidrotic areas. Increased insensible perspiration increased SC hydration as well as NMFs other than AAs and PCA. CONCLUSION: Sweat constitutes lactate, urea, sodium, and potassium in NMFs and plays a crucial role in maintaining the physiological hydration state of SC.

KIAA1199, a deafness gene of unknown function, is a new hyaluronan binding protein involved in hyaluronan depolymerization.

Hyaluronan (HA) has an extraordinarily high turnover in physiological tissues, and HA degradation is accelerated in inflammatory and neoplastic diseases. CD44 (a cell surface receptor) and two hyaluronidases (HYAL1 and HYAL2) are thought to be responsible for HA binding and degradation; however, the role of these molecules in HA catabolism remains controversial. Here we show that KIAA1199, a deafness gene of unknown function, plays a central role in HA binding and depolymerization that is independent of CD44 and HYAL enzymes. The specific binding of KIAA1199 to HA was demonstrated in glycosaminoglycan-binding assays. We found that knockdown of KIAA1199 abolished HA degradation by human skin fibroblasts and that transfection of KIAA1199 cDNA into cells conferred the ability to catabolize HA in an endo-ß-N-acetylglucosaminidase-dependent manner via the clathrin-coated pit pathway. Enhanced degradation of HA in synovial fibroblasts from patients with osteoarthritis or rheumatoid arthritis was correlated with increased levels of KIAA1199 expression and was abrogated by knockdown of KIAA1199. The level of KIAA1199 expression in uninflamed synovium was less than in osteoarthritic or rheumatoid synovium. These data suggest that KIAA1199 is a unique hyaladherin with a key role in HA catabolism in the dermis of the skin and arthritic synovium.

Low-flux electron diffraction study for the intercellular lipid organization on a human corneocyte.

Human skin stratum corneum (SC) structures were investigated by electron diffraction (ED) with a very low-flux electron beam with the help of high-sensitivity detectors, the imaging plate and the CCD camera. This low-flux electron diffraction (LFED) method made it possible to minimize the unfavorable effect of electron beam damage and to give a reliable diffraction pattern from a small selected area (0.2µm(2)) on a corneocyte. Dependence of the 2-dimensional ED pattern on the size of the selected area showed that orientational correlation between lipid packing domains can persist over the area much larger than their domain size. The LFED method also allowed us to trace the detailed structural change induced by the electron beam damage. The ED diffraction peak for the lattice constant of about 4.1nm decayed in three steps. The detailed analysis of these three steps suggested that a different type of orthorhombic structure exists interacted with the well-described hexagonal and orthorhombic structures, in the process of decay resulting from electron beam damage.

High-resolution ultrasound imaging of human skin in vivo by using three-dimensional ultrasound microscopy.

Observing the morphology of human skin is important in the diagnosis of skin cancer and inflammation and in the assessment of skin aging. High-frequency ultrasound imaging provides high spatial resolution of the deep layers of the skin, which cannot be visualized by optical methods. The objectives of the present study were to develop a three-dimensional (3-D) ultrasound microscope and to observe the morphology of normal human skin in vivo. A concave polyvinylidene fluoride transducer with a central frequency of 120 MHz was excited using an electric pulse generated by semiconductor switching. The transducer was scanned two-dimensionally by using two linear motors on the region-of-interest and the ultrasonic reflection was digitized with 2-GHz sampling. Consecutive B-mode images perpendicular to the skin surface were reconstructed to generate multiplanar reconstructed images and 3-D volume-rendering images clearly showing microstructures such as sebaceous glands and hair follicles. The 3-D ultrasound microscope could be used to successfully image the morphology of human skin noninvasively and may provide important information on skin structure.

Reduced size of sebaceous gland and altered sebum lipid composition in mice lacking fatty acid binding protein 5 gene.

Fatty acid binding proteins (FABPs) are capable of binding long-chain FA and are involved in intracellular FA transport and signal transduction. In sebaceous glands, FABP5 is highly expressed in differentiated sebocytes; though, its function remains unclear. In this study, we examined the role of FABP5 in sebocytes using FABP5-deficient mice. The size of sebaceous glands was significantly reduced, while the sebum volume was increased with altered lipid composition in FABP5-deficient mice. However, no significant differences were discerned in the expression of proliferation or differentiation markers including Blimp1, c-myc, Ki67 and peroxisome proliferator-activated receptors (PPAR)γ between wild-type and FABP5-deficient sebaceous glands. The expression of cellular retinoic acid binding protein-2 (CRABP2) that is a competitor of FABP5 for RA signalling was increased in FABP5-deficient mice. These results suggest that FABP5 is involved in the regulation of sebaceous gland activity through modulation of cellular lipid signalling and/or metabolism in the sebocytes.

Decreased lactate and potassium levels in natural moisturizing factor from the stratum corneum of mild atopic dermatitis patients are involved with the reduced hydration state.

BACKGROUND: Atopic dermatitis (AD) shows dry skin. Water-soluble, low molecular weight components, collectively known as natural moisturizing factor (NMF), play an important role in maintaining the stratum corneum (SC) hydration. Previous studies focused on reduced levels of free amino acids (FAAs) in NMF from AD skin. It remains unknown, however, whether other NMF components are also altered in AD. OBJECTIVE: To characterize the levels of various NMF components in the SC of healthy subjects and in mild AD adult patients. METHODS: NMF components were extracted from three sequential tape-stripped SC samples obtained from the volar forearm. NMF components which were decreased in AD skin were topically applied to examine their contribution to SC moisturization in AD skin. RESULTS: We found that although FAAs levels were not remarkably reduced, levels of pyrrolidone carboxylic acid (PCA), lactate, urea, sodium and potassium were significantly decreased in NMF from mild AD skin. Among those components, only the topical application of potassium lactate effectively increased skin surface hydration indicating that reductions of lactate and potassium influence dry skin in mild AD patients. Unlike the distribution of filaggrin-derived FAAs and PCA, lactate, urea, potassium and sodium were abundant in the surface layer of the SC compared with the inner layer of the SC. Such findings strongly suggest that those components are supplied from outside the SC, i.e. they originate from sweat. CONCLUSION: The reduced levels of sweat-derived NMF components in mild AD patients suggests that impaired sweat function might in part result in the SC dryness.

In vivo evaluation of human skin anisotropy by polarization-sensitive optical coherence tomography.

We performed an in vivo three-dimensional analysis of anisotropic changes in the dermal birefringence of mechanically deformed human skin using polarization-sensitive optical coherence tomography (PS-OCT). The papillary-dermal birefringence of the forehead increased significantly when the skin was shrunk parallel to the body axis, and decreased significantly when the skin was shrunk perpendicular to the body axis. En-face images of the papillary-dermal birefringence revealed variations among individual subjects, and that both shrinking parallel to and stretching in perpendicular to the body axis promoted the formation of macro rope-like birefringent domains. We found that PS-OCT is useful for understanding anisotropic properties of collagen structure in the skin.

Hydrating effect of potassium lactate is caused by increasing the interaction between water molecules and the serine residue of the stratum corneum protein.

Natural moisturizing factors (NMFs) play an important role in maintaining the physical properties of the stratum corneum (SC). The relationship between SC water content and NMFs has long been investigated. Recently, we demonstrated that potassium lactate as an NMF increased SC water content more than sodium lactate did. The details of the moisturizing mechanism of NMFs, however, were not revealed. We, therefore, investigated the cause of the SC moisturizing effect of potassium lactate in comparison with sodium lactate. Using differential scanning calorimetry, we found that potassium lactate increased the bound water content of plantar SC more than what sodium lactate did. We also found, however, that the bound water content of the potassium lactate solution was less than that of the sodium lactate solution, suggesting that potassium lactate increased the water molecules interacting with SC components. Moreover, potassium lactate increased the ratio of hydrogen/deuterium exchange at 1340/cm, which represents the OH bending mode, of plantar SC spectra obtained by the attenuated total reflectance infrared spectroscopy. We assign this band to the OH group of the serine residue. These results suggest that potassium lactate increases the water-holding capacity of the SC by increasing interaction between water molecules and the OH group of serine in SC keratin.

In vivo measurement of the water content in the dermis by confocal Raman spectroscopy.

BACKGROUND/PURPOSE: Dermal water plays an important role in the physical properties of the skin. Recently, researchers have attempted to directly measure the dermal water content in vivo using magnetic resonance imaging, near infrared spectroscopy, and Raman spectroscopy. However, these methods have limitations. Although confocal Raman spectroscopy has been developed to measure the water content in the skin, no reports have suggested that this instrument can measure the dermal water content. This report describes a method for measuring the dermal water content in vivo using confocal Raman spectroscopy. METHODS: We used a confocal Raman spectrometer and adjusted the laser exposure time and depth increments according to the skin depth. Age-related changes in the dermal water content of the forearm were examined in 30 young and 30 elderly male subjects. Diurnal changes in the dermal water content of the forearm were examined in 12 elderly male subjects. RESULTS: Adjusting the exposure time and depth increment dramatically improved the signal-to-noise ratios of the Raman spectra. Elderly dermis had significantly higher water content than young dermis. Moreover, the dermal water content displayed a diurnal change. CONCLUSION: This study demonstrates that the dermal water content can be measured in vivo using confocal Raman spectroscopy.

Imaging of melanin distribution using multiphoton autofluorescence decay curves.

BACKGROUND/PURPOSE: Multiphoton fluorescence lifetime imaging (FLIM) is a technique that produces an image based on differences in the decay rate of fluorescence from a sample. Based on this method, the DermaInspect was developed to observe human skin components non-invasively. In this study, we used the DermaInspect to study melanin in skin. METHODS: A human three-dimensional skin model containing melanocytes was embedded in an OCT compound, frozen and sectioned at 10 microm. The melanin distribution in each section was visualized by the DermaInspect using time-resolved single-photon counting and near-infrared femtosecond laser pulse excitation. The melanin distribution of the same sections was then visualized using the Fontana-Masson staining method. RESULTS: High-resolution images were generated from the ratio of a(1)/a(2) (a(1)e(-) (t/120)+a(2)e(-) (t/1100) was chosen to express the exponential fluorescent decay curve) obtained using the DermaInspect. Granules with a high a(1)/a(2) ratio, approximately 1 mum in diameter, were observed. Fontana-Masson staining identified these granules as melanin. This new technique was then applied for in vivo observation of melanin in human skin. 'Melanin caps' were visualized in the basal cell layer around the nuclei in images derived from the a(1)/a(2) ratio. CONCLUSION: Our study confirms that FLIM can non-invasively provide data of the melanin distribution with almost the same quality as the conventional Fontana-Masson staining method, and demonstrates that FLIM is useful for in vivo observation of melanin granules in human skin.

Visibility of trabecular meshwork by standard and polarization-sensitive optical coherence tomography.

Polarization-sensitive optical coherence tomography (PS-OCT) is known to be advantageous because of its additional tissue-specific contrast of the anterior eye. So far, this advantage has been shown only qualitatively. We evaluate the improved visibility afforded by 3-D PS corneal and anterior eye segment OCT (PS-CAS-OCT) in visualizing the trabecular meshwork (TM) based on statistical evidences. A total of 31 normal subjects participated in this study. The anterior eye segments of both the eyes of the subjects are scanned using a custom-made PS-CAS-OCT and the standard-scattering OCT (S-OCT) and polarization-sensitive phase-retardation OCT (P-OCT) images are obtained. Three graders grade the visibility of the TM using a four-leveled grading system. The intergrader agreement, intermodality differences, and interquadrant dependence of visibility are statistically examined. All three of three combinations of graders show substantial agreement in visibility with P-OCT (ρ = 0.74, 0.70, and 0.68, Spearman's correlation), while only one of three shows substantial agreement with S-OCT (ρ = 0.72). Significant dependence of the visibility on the modality (S-OCT versus P-OCT) and quadrants are found by the analysis of variance. A subsequent Wilcoxon signed-rank test reveals significantly improved visibility. PS-CAS-OCT may become a useful tool for screening angle-closure glaucoma.