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).

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.

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.

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.

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.

Relationship between dermal birefringence and the skin surface roughness of photoaged human skin.

The dermal degeneration accompanying photoaging is considered to promote skin roughness features such as wrinkles. Our previous study demonstrated that polarization-sensitive spectral domain optical coherence tomography (PS-SD-OCT) enabled noninvasive three-dimensional evaluation of the dermal degeneration of photoaged skin as a change in dermal birefringence, mainly due to collagenous structures. Our purpose is to examine the relationship between dermal birefringence and elasticity and the skin morphology in the eye corner area using PS-SD-OCT.

In vivo three-dimensional birefringence analysis shows collagen differences between young and old photo-aged human skin.

Polarization-sensitive optical coherence tomography (PS-OCT) permits non-invasive visualization of dermal birefringence, mainly due to collagenous structures. The purpose of this study is to use PS-OCT to assess intrinsic-age-related and photo-age-related differences in three-dimensional dermal birefringence. We measured dermal birefringence of the cheek skin and photo-protected interior upper arm skin from old and young volunteers.

Relationship between NMF (lactate and potassium) content and the physical properties of the stratum corneum in healthy subjects.

Natural moisturizing factor (NMF) of the stratum corneum (SC) has been established to play important roles in the physical properties of the SC. Few studies, however, have investigated the specific influences of NMF components other than the amino acids. In this study, therefore, we focus on the relationship between the ion content and physical properties of the SC in 40 healthy subjects.