Objective Current perception threshold (CPT) measurement is a noninvasive, easy, and semi‐objective method for determining sensory function using transcutaneous electrical stimulation. Previous studies have shown that CPT is determined by physical characteristics, such as sex, age, physical sites, and presence of neuropathy. Although the CPT reported in males is clearly higher than that in females, the reason for this difference remains unclear. This study investigates the cause of sex‐based differences in CPT and suggests an adjustment method, which may suppress the sex difference in CPT. Materials and Methods Electrical stimulation was applied with PainVision® via five sizes of circular surface electrodes. Seventy healthy participants were examined thrice under each electrode. The relationship among body water percentage, body fat percentage, and CPT was then analyzed. Results CPT values are higher in males than that in females, with statistically significant sex differences with each electrode pairs (EL 1: p < 0.001; EL 2: p = 0.006; EL 3: p < 0.001; EL 4: p < 0.001; EL 5: p < 0.001). By adjusting for body fat percentage or body water percentage, the log‐transformation values (CPT values) no longer exhibit sex differences with any electrode pairs (body fat: p = 0.09; body water: p = 0.08). Conclusion We conclude that sensitivity for perceiving electrical stimulation can be influenced by the subjects' characteristics, such as body fat or body water percentages.

Sweating, the intermittent secretion of uid from the sweat glands, is an indispensable mechanism for the regulation of body temperature. The methods used to measure the sweat rate include an iodine starch test, a weight assay, and an ion electric conductivity method. The ventilation capsule method is another method for quanti cation of sweat rate. However, this method has a problem in that the subject s physical activity is restricted by the rmly attached measurement probes. SNT-200, a wearable sweat meter developed by Rousette Strategy Inc., is already commercially available. This sweat meter contains silica gel that serves as an absorbent for sudoriferous steam and uses a temperature-humidity sensor to detect humidity changes in the device caused by sweating. However, the accuracy of the measurement has not yet been suf ciently investigated. This study was designed to provide evidence to validate the underlying measurement principle and accuracy of the device. We simulated various sweating conditions and performed simulated sweating measurements using SNT-200. In the rst experiment, continuous sweating over a wide body surface was simulated. The calculated absorbed steam volume was 1.84 times greater than the real transpiration rate. In the second experiment, sweating was simulated in the form of water drops, and the sweat meter absorbed the generated steam. In the second experiment, the data obtained using SNT-200 was in good accord with the volume dispensed by a micropipette. These experiments provided convincing evidence that the total area of four steam holes (A1, in the equation for calculating the sweat rate) required correction. We therefore modeled the effective absorption area of the sweat meter as one circle encompassing the four holes (8 mm in diameter; 52 mm 2) instead of a summation of the areas of four steam holes. De ning the effective absorption area by this method modi ed the value calculated in the rst experiment, which agreed with the transpiration rate. In addition, the modi ed moisture absorption volume in the sweat meter converged within ± 20% error of the actual measurement, except at 30 C.

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Objective This study aimed to measure the current perception threshold (CPT) of five fingertips of the left hand in healthy subjects and analyze whether sex differences in perception thresholds are suppressed when adjusting for fingertip size among males and females. Results For fingertips from the thumb to the little finger, the males’ CPT values were 1.03, 0.83, 0.86, 0.86, and 0.88 mA; the females’ results were 0.63, 0.55, 0.54, 0.51, and 0.50 mA. The CPTs were higher in males than in females for every fingertip. Upon adjusting for fingertip length, the log-transformed CPT values were found to have sex differences, except for the index finger: thumb, t(20.05) = 3.493, p = 0.002; middle finger, U(30) = 44.50, p = 0.005; ring finger, t(30) = 55.50, p = 0.018; little finger, U(30) = 30.00, p = 0.001. Similarly, the CPT values, transformed into log values when adjusting for the fingertip area, were found to have sex differences for three fingertips: thumb, t(18) = 2.649, p = 0.016; middle finger, U(20) = 12.00, p = 0.004; ring finger, t(18) = 2.206, p = 0.041. According to this study, sex differences in CPTs were not completely abolished by adjusting for fingertip length or area.

A kinetic study of capsaicin (CAP) toward radicals has been performed using stopped-flow spectrophotometry in detail. The second-order rate constants (k2) for the reaction of CAP toward 2,2-diphenyl-1-picrylhydrazyl (DPPH) and galvinoxyl have been measured in methanol, ethanol, 2-propanol/water (5:1, v/v), and aqueous micellar suspensions containing 5% Triton X-100 (pH 4.0 to 10.0), respectively. The decay rates of DPPH and galvinoxyl for the reaction with CAP increased linearly in a concentration-dependent manner in homogeneous solutions and aqueous micellar suspensions. However, the k2 for CAP obtained in an aqueous micellar suspension showed notable pH dependence; that is, the reactivity of CAP increased with an increasing pH value from 4 to 10. In addition, a good correlation between the k2 value and the molar fraction of CAP (phenolate anion (CAP-O(-))/undeprotonated form (CAP-OH)) was observed. These properties are associated with the pKa of CAP. Furthermore, it was found that the CAP-O(-) reacts with galvinoxyl about 6 times as fast as the CAP-OH. These results indicate that sequential proton loss electron transfer from the phenolic hydrogen of CAP may be responsible for the scavenging of radicals in an aqueous micellar suspensions.

Background Transepidermal water loss (TEWL) is often used as an index for skin barrier function. The skin barrier tester, SBT‐100 (Rousette Strategy Inc), measures the TEWL, water evaporation time, and time constant by contacting the skin and diffusing water into the closing measurement chamber. However, the relationship between the TEWL and time constant has not been sufficiently investigated. This study involved analyzing the underlying measurement principle and obtaining data through two experiments. Materials and methods The TEWL and time constant were measured using SBT‐100. Experiment 1 produced a simple simulation model for continuous water evaporation from the skin using a moisture‐permeable film. In experiment 2, four skin sites of 43 healthy volunteers were examined from May to September 2018. Results In experiment 1, the TEWL increased and time constant decreased, following an increase in humidity in the external environment. Both parameters demonstrated significant negative correlation (drying: ρ = −0.832, p < 0.001). For the 43 healthy volunteers who participated in experiment 2, their TEWL increased and time constant decreased in summer. For all skin measurement sites, both data demonstrated significant negative correlation (forehead: ρ = −0.909, p < 0.001; back of the left hand: ρ = −0.829, p < 0.001; left lateral elbow: ρ = −0.896, p < 0.001; left lateral malleolus: ρ = −0.865, p < 0.001). Conclusion Results indicated that the time constant is significantly correlated with TEWL. Furthermore, the time constant can be used as a parameter for evaluating skin barrier function.