Biology subjects

Youn, S.

Publications and source records attributed to Youn, S..

3 recordsLinked to original sources

bioRxiv2024

Physiological Evaluation of Far Infrared-Emitting Garments on Sleep and Thermoregulation

Garments engineered to emit far-infrared (FIR) spectral frequencies have potential conditioning benefits. This study aimed to explore the physiological effects of FIR-emitting clothes on sleep propensities involving thermoregulation and autonomic nervous function. In this double-blind, randomized, placebo-controlled, crossover study, fifteen healthy male participants (age 21.6 {+/-} 1.5 years, body mass index 23.1 {+/-} 1.9, Pittsburgh Sleep Quality Index 5.0 {+/-} 2.0) wore a whole-body FIR garment (wavelength: 5-20 m at 40{degrees}C), while a total body garment with the 100% polyester fiber without ceramic components was used as control for the intervention. To compare the physiological variables between the two electroencephalograms, the tympanic membrane temperature, sweating rate, skin temperature, and humidity were measured during sleep. Heart rate variability during sleep was also calculated. The percentage of rapid eye movement (REM) sleep was significantly higher in the FIR compared than in control (p = 0.027). We found a significant main effect of tympanic membrane temperature in time, equivalent to core body temperature. (2-way ANOVA; (F(26, 234)=4.046, p<0.001). Furthermore, the sweating rate was significantly lower when sleeping with FIR predominantly in the final phase of sleep (garment x time interaction (F(26,572)=55.05, p<0.001). Although there were no significant differences in skin surface temperature between the two garments, FIR provided significantly lower skin humidity during the middle of night sleep compared with the control. Regarding LF, a significant garment type x time interaction (F(1.87, 48.57)=3.36, p=0.046). Post-hoc analysis revealed that the LF value of FIR was higher in the final phase of sleep than that of control (p=0.027). Then present results suggest that sleeping with FIR in comparison to with control, has a beneficial effect to facilitate restorative sleep, presumably involving proper thermoregulation.

neuroscience↗

bioRxiv2018

Elaborate pupils in skates may help camouflage the eye

The little skate Leucoraja erinacea has elaborately shaped pupils, whose characteristics and functions have not been studied extensively. It has been suggested that such pupil shapes may camouflage the eye; yet, no experimental evidence has been presented to support this claim. Skates are bottom-dwellers that often bury into the substrate with their eyes protruding. If these pupils serve any camouflage function, we expect there to be a pupillary response related to the spatial frequency (\"graininess\") of the background against which the eye is viewed. Here, we tested whether skate pupils dilate or constrict in response to background spatial frequency. We placed skates on background substrates with different spatial frequencies and recorded pupillary responses at three light intensities. In experiment 1, the skates pupillary response to three artificial checkerboards of different spatial frequencies was recorded. Skates responded to changing light intensity with pupil dilation/constriction; yet, their pupils did not change in response to spatial frequency. In experiment 2, in which skates could bury into three natural substrates with different spatial frequencies, such that their eyes protruded above the substrate, the pupils showed a subtle but statistically significant response to changes in substrate spatial frequency. Given the same light intensity, the smaller the spatial frequency of the natural substrate, the more constricted the pupil. While light intensity is the primary factor determining pupil dilation, these experiments are the first to show that pupils also change in response to background spatial frequency, which suggests that the pupil may aid in camouflaging the eye.

animal behavior and cognition↗

bioRxiv2017

Measurements of three-dimensional refractive index tomography and membrane deformability of live erythrocytes from Pelophylax nigromaculatus

Unlike mammalian erythrocytes, amphibian erythrocytes have distinct morphological features including large cell sizes and the presence of nuclei. The sizes of the cytoplasm and nuclei of erythrocytes vary significantly over different species, their environments, or pathophysiology, which makes hematological studies important for investigating amphibian species. Here, we present a label-free three-dimensional optical quantification of individual amphibian erythrocytes from frogs Pelophylax nigromaculatus (Rana nigromaculata). Using optical diffraction tomography, we measured three-dimensional refractive index (RI) tomograms of the cells, which clearly distinguished the cytoplasm and nuclei inside the erythrocytes. From the measured RI tomograms, we extracted the relevant biochemical parameters of the cells, including hemoglobin contents and hemoglobin concentrations. Furthermore, we measured dynamic membrane fluctuations and investigated the mechanical properties of the cell membrane. From the statistical and correlative analysis of these retrieved parameters, we investigated interspecific differences between frogs and previously studied mammals.

biophysics↗