Examination of the utility of skin carotenoid status in estimating dietary intakes of carotenoids and fruits and vegetables: A randomized, parallel-group, controlled feeding trial.

OBJECTIVE: Optical spectroscopy-measured skin carotenoid status (SCS) has been validated for estimating fruit and vegetable (F&V) intake; however, there is limited research addressing SCS kinetics in whole-diet interventions. The aim of this controlled feeding trial was to explore SCS's response to carotenoid intake changes via whole-diet intervention, evaluating its biomarker potential. METHODS: Eighty participants ages 20 to 49 y, without underlying diseases, were randomly allocated to the high-carotenoid group (HG; n = 40) or control group (CG; n = 40). The HG consumed a high-carotenoid diet (21 mg total carotenoids/2000 kcal), whereas the CG consumed a control diet (13.6 mg total carotenoids/2000 kcal) for 6 wk. Subsequently, skin and blood carotenoid concentrations were tracked without intervention for 4 wk. SCS was measured weekly via resonance Raman spectroscopy, and serum carotenoid concentrations were analyzed biweekly using high-performance liquid chromatography. Baseline carotenoid and F&V intakes were assessed via a 3-d diet record. The kinetics of SCS and serum carotenoid concentrations were analyzed using a weighted generalized estimating equation. Pearson's correlation analyses were used to examine baseline correlations between SCS and dietary carotenoid and F&V intakes, as well as serum carotenoid concentrations. RESULTS: During the intervention, the HG showed a faster and greater SCS increase than the CG (difference in slope per week = 8.87 AU, Pinteraction <0.001). Baseline SCS had positive correlations with total carotenoid intake (r = 0.45), total F&V intake (r = 0.49), and total serum carotenoid concentration (r = 0.79; P < 0.001 for all). CONCLUSION: These results suggest that SCS is a valid biomarker for monitoring changes in carotenoid intake through whole diet, which supports using SCS for assessing carotenoid-rich F&V intake.

Evaluation of a Commercial Device Based on Reflection Spectroscopy as an Alternative to Resonance Raman Spectroscopy in Measuring Skin Carotenoid Levels: Randomized Controlled Trial.

Resonance Raman spectroscopy (RRS) has been used as a reference method for measuring skin carotenoid levels (SCL), which indicate vegetable and fruit intake. However, RRS is not an easy-to-use method in SCL measurement due to its complicated implementation. In this study, a commercial spectrophotometer based on reflection spectroscopy (RS), which is relatively simple and inexpensive, was evaluated to confirm usability compared with RRS in measuring SCL. To investigate the agreement between RS and RRS, eighty participants were randomly assigned to a high-carotenoid diet group (21 mg/day of total carotenoids) or a control-carotenoid diet group (14 mg/day of total carotenoids) during a 6-week whole-diet intervention period and a 4-week tracking period. Strong correlations between the RS and RRS methods were observed at baseline (r = 0.944) and the entire period (r = 0.930). The rate of SCL increase was similar during the diet intervention; however, the initiation of the SCL decrease in RS was slower than in RRS during the tracking period. To confirm the agreement of RS and RRS from various perspectives, new visualization tools and indices were additionally applied and confirmed the similar response patterns of the two methods. The results indicate that the proposed RS method could be an alternative to RRS in SCL measurements.

Validation of resonance Raman spectroscopy-measured skin carotenoid status as a biomarker for fruit and vegetable intake in Korean adults.

Blood carotenoid concentration measurement is considered the gold standard for fruit and vegetable (F&V) intake estimation; however, this method is invasive and expensive. Recently, skin carotenoid status (SCS) measured by optical sensors has been evaluated as a promising parameter for F&V intake estimation. In this cross-sectional study, we aimed to validate the utility of resonance Raman spectroscopy (RRS)-assessed SCS as a biomarker of F&V intake in Korean adults. We used data from 108 participants aged 20-69 years who completed SCS measurements, blood collection and 3-d dietary recordings. Serum carotenoid concentrations were quantified using HPLC, and dietary carotenoid and F&V intakes were estimated via 3-d dietary records using a carotenoid database for common Korean foods. The correlations of the SCS with serum carotenoid concentrations, dietary carotenoid intake and F&V intake were examined to assess SCS validity. SCS was positively correlated with total serum carotenoid concentration (r = 0·52, 95 % CI = 0·36, 0·64, P < 0·001), serum ß-carotene concentration (r = 0·60, 95 % CI = 0·47, 0·71, P < 0·001), total carotenoid intake (r = 0·20, 95 % CI = 0·01, 0·37, P = 0·04), ß-carotene intake (r = 0·30, 95 % CI = 0·11, 0·46, P = 0·002) and F&V intake (r = 0·40, 95 % CI = 0·23, 0·55, P < 0·001). These results suggest that SCS can be a valid biomarker of F&V intake in Korean adults.

What drives the use of wearable healthcare devices? A cross-country comparison between the US and Korea.

Objective: Given the rapid growth of the wearable healthcare device market, we examined the associations among health-related and technology-related characteristics of using wearable healthcare devices and demonstrated how the associations differ between the US and Korean users. Methods: Online self-administered surveys were conducted with 4098 participants (3035 in the US and 1063 in Korea) who were recruited through two online survey service providers based on quota sampling. The primary outcome was the use of wearable healthcare devices. Seven health-related, two technology-related, and five socio-demographic factors were included as explanatory variables. Binary logistic regression analyses and a Chow test were conducted. Results: The health-related characteristics that were significantly associated with using wearable healthcare devices included disease-related worries (ß = 0.11**), health information seeking (ß = 0.26***), physical activity (ß = 0.62***), and health-related expenditures ($50-$199, ß = 0.38***; $200 or more, ß = 0.56***). Hedonic (ß = 0.33***), social (ß = 0.31***), and cognitive innovativeness (ß = 0.14*) also exhibited positive relationships. Younger, higher earner, and individuals with a child were more likely to use wearable healthcare devices. However, for Korean users, several associations disappeared including health information seeking, hedonic and social innovativeness, age, and household income. Conclusions: Key drivers of using wearable healthcare devices include greater concern about a specific illness, active engagement in health-promoting behaviors, and hedonic and social motivation to adopt new technologies. However, more country-specific considerations are needed in future studies to identify the main benefits for target markets.

Wrist-wearable bioelectrical impedance analyzer with miniature electrodes for daily obesity management.

Bioelectrical impedance analysis (BIA) is used to analyze human body composition by applying a small alternating current through the body and measuring the impedance. The smaller the electrode of a BIA device, the larger the impedance measurement error due to the contact resistance between the electrode and human skin. Therefore, most commercial BIA devices utilize electrodes that are large enough (i.e., 4 × 1400 mm2) to counteract the contact resistance effect. We propose a novel method of compensating for contact resistance by performing 4-point and 2-point measurements alternately such that body impedance can be accurately estimated even with considerably smaller electrodes (outer electrodes: 68 mm2; inner electrodes: 128 mm2). Additionally, we report the use of a wrist-wearable BIA device with single-finger contact measurement and clinical test results from 203 participants at Seoul St. Mary's Hospital. The correlation coefficient and standard error of estimate of percentage body fat were 0.899 and 3.76%, respectively, in comparison with dual-energy X-ray absorptiometry. This result exceeds the performance level of the commercial upper-body portable body fat analyzer (Omron HBF-306). With a measurement time of 7 s, this sensor technology is expected to provide a new possibility of a wearable bioelectrical impedance analyzer, toward obesity management.

Temperature Correction to Enhance Blood Glucose Monitoring Accuracy Using Electrical Impedance Spectroscopy.

Electrical methods are among the primarily studied non-invasive glucose measurement techniques; however, various factors affect the accuracy of the sensors used. Of these, the temperature is a critical factor; hence, the effects of temperature on the electrical properties of blood components are investigated in this study. Furthermore, the changes in the electrical properties of blood according to the glucose level are corrected by considering the effects of temperature on the electrical properties. An impedance sensor is developed and used to measure whole blood impedance in 10 healthy participants at various temperatures and glucose levels. Subsequently, the conductivities of the plasma and cytoplasm were extracted. Changes in the electrical properties of the blood components are then analyzed using linear regression and repeated measures ANOVA. The electrical conductivities of plasma and cytoplasm increased with increasing temperatures (plasma: 0.0397 (slope), 0.7814 (R2), cytoplasm: 0.014 (slope), 0.694 (R2)). At three values of increasing glucose levels (85.4, 158.1, and 271.8 mg/dL), the electrical conductivities of the plasma and cytoplasm decreased. These tendencies are more significant upon temperature corrections (p-values; plasma: 0.001, 0.001, cytoplasm: 0.003, 0.002). The relationships between temperature and electrical conductivity changes can thus be used for temperature corrections in blood glucose measurement.

Design of Bio-Impedance Electrode Topologies for Specific Depth Sensing in Skin Layer.

Bio-impedance analysis provides non-invasive estimation of body composition. Recently, applications based on bio-impedance measurement in skin tissue such as skin cancer diagnosis and skin composition monitoring have been studied. For scanning the electrical properties along the skin depth, the relationship between the electrode topologies and the depth sensitivity should be clarified. This work reports a systematic analysis on designing line electrode topologies to measure the bio-impedance of the skin layer at specific depth using a finite element method (FEM). Four electrodes consisting of two outer current electrodes and two inner voltage electrodes in the form of Wenner-Schlumberger array were employed on the top of a collagen layer as a skin model. The numerical results demonstrate a change in the effective depth of measurement depending on the electrode topologies, which also have a good agreement with an analytic solution. This study suggests a decision guideline for designing the electrode topologies to achieve target depth sensitivity in bio-impedance measurement of skin tissue.Clinical Relevance-This establishes the effect of electrode topologies on depth sensitivity in bio-impedance measurements in skin layer.

Focusing of light by negative refraction in a photonic crystal slab superlens on silicon-on-insulator substrate.

We experimentally demonstrate the light focusing by negative refraction in a photonic crystal slab superlens at wavelengths lambda of 1.26-1.42 microm. The photonic crystal slab was fabricated on silicon-on-insulator substrate with an interface structure optimized for low reflection and diffraction losses. The light focusing in the photonic crystal slab was clearly observed through the intentional out-of-plane radiation or scattering of guided light in the slab. The minimum focused spot width was limited to 1.8 microm(1.4 lambda) owing to aberrations. The focusing characteristics were in good agreement with those obtained from photonic band and finite-difference time-domain analyses.