Na⁺/H⁺ Exchanger Regulatory Factor 3 Is Critical for Multidrug Resistance Protein 4-Mediated Drug Efflux in the Kidney

Park, Joonhee,Kwak, Jin-Oh,Riederer, Brigitte,Seidler, Ursula,Cole, Susan P.C.,Lee, Hwa Jeong,Lee, Min Goo American Society of Nephrology 2014 Journal of the American Society of Nephrology Vol.25 No.4

<P>Na(+)/H(+) exchanger regulatory factor 3 (NHERF3) is a PSD-95/discs large/ZO-1 (PDZ)-based adaptor protein that regulates several membrane-transporting proteins in epithelia. However, the in vivo physiologic role of NHERF3 in transepithelial transport remains poorly understood. Multidrug resistance protein 4 (MRP4) is an ATP binding cassette transporter that mediates the efflux of organic molecules, such as nucleoside analogs, in the gastrointestinal and renal epithelia. Here, we report that Nherf3 knockout (Nherf3(-/-)) mice exhibit profound reductions in Mrp4 expression and Mrp4-mediated drug transport in the kidney. A search for the binding partners of the COOH-terminal PDZ binding motif of MRP4 among several epithelial PDZ proteins indicated that MRP4 associated most strongly with NHERF3. When expressed in HEK293 cells, NHERF3 increased membrane expression of MRP4 by reducing internalization of cell surface MRP4 and consequently, augmented MRP4-mediated efflux of adefovir, a nucleoside-based antiviral agent and well known substrate of MRP4. Examination of wild-type and Nherf3(-/-) mice revealed that Nherf3 is most abundantly expressed in the kidney and has a prominent role in modulating Mrp4 levels. Deletion of Nherf3 in mice caused a profound reduction in Mrp4 expression at the apical membrane of renal proximal tubules and evoked a significant increase in the plasma and kidney concentrations of adefovir, with a corresponding decrease in the systemic clearance of this drug. These results suggest that NHERF3 is a key regulator of organic transport in the kidney, particularly MRP4-mediated clearance of drug molecules.</P>

Graphene quantum dots: structural integrity and oxygen functional groups for high sulfur/sulfide utilization in lithium sulfur batteries

Park, Jungjin,Moon, Joonhee,Kim, Chunjoong,Kang, Jin Hyoun,Lim, Eunhak,Park, Jaesung,Lee, Kyung Jae,Yu, Seung-Ho,Seo, Jung-Hye,Lee, Jouhahn,Heo, Jiyoung,Tanaka, Nobuo,Cho, Sung-Pyo,Pyun, Jeffrey,Caban Nature Publishing Group 2016 NPG Asia Materials Vol.8 No.-

<P>Lithium-sulfur (Li-S) batteries are expected to overcome the limit of current energy storage devices by delivering high specific energy with low material cost. However, the potential of Li-S batteries has not yet been realized because of several technical barriers. Poor electrochemical performance is mainly attributed to the low electrical conductivity of the fully charged and discharged species, the irreversible loss of polysulfide anions and the decrease in the number of electrochemically active reaction sites during battery operation. Here, we report that the introduction of graphene quantum dots (GQDs) into the sulfur cathode dramatically enhanced sulfur/sulfide utilization, yielding high performance. In addition, the GQDs induced structural integrity of the sulfur-carbon electrode composite by oxygen-rich functional groups. This hierarchical architecture enabled fast charge transfer while minimizing the loss of lithium polysulfides, which is attributed to the physicochemical properties of GQDs. The mechanisms through which excellent cycling and rate performance are achieved were thoroughly studied by analyzing capacity versus voltage profiles. Furthermore, experimental observations and theoretical calculations further clarified the role played by GQDs by proving that C-S bonding occurs. Thus, the introduction of GQDs into Li-S batteries will provide an important breakthrough allowing their use as high-performance and low-cost batteries for next-generation energy storage systems.</P>

Effects of alternating exposure to cold and heat for 14 days on cold tolerance in winter

Park, Joonhee,Shin, Sora,Lee, Joo-Young Elsevier 2019 Journal of thermal biology Vol.79 No.-

<P><B>Abstract</B></P> <P>People are exposed to heat regularly due to their jobs or daily habits in cold winter, but few studies have reported whether parallel heat and cold exposure and diminish cold acclimation. This study was conducted to investigate the effects of alternating exposure to cold and heat on cold tolerance in eight young males. A daily acclimation program to cold and heat, which consisted of 2-h sitting at 10 °C air in the morning and 2-h running and rest at 30 °C air in the afternoon, was conducted for 14 consecutive days. Eight male subjects participated in a cold tolerance test (10 °C [ ± 0.3], 40%RH[ ± 3]) before (PRE) and after (POST) completing the alternating exposure program. During the cold tolerance test, subjects remained sitting upright on a chair for 60 min. Rectal temperature (T<SUB>re</SUB>) was lower in POST than in PRE during the 60-min cold tolerance test (<I>P</I> = 0.027). During the cold tolerance test, systolic, diastolic, and mean arterial blood pressures in POST were lower than those in PRE (<I>P</I> = 0.006, <I>P</I> = 0.005, and <I>P</I> = 0.004). No significant differences in skin temperatures between PRE and POST were found for the cold tolerance test. There were no significant differences in energy expenditure during cold exposure between PRE and POST. Subjects felt less cold in POST than in PRE (<I>P</I> = 0.013) whereas there was no significant difference in overall thermal comfort between PRE and POST. These results suggest that cold adaptation can still occur in the presence of heat stress.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effects of alternating exposure to cold and heat on cold tolerance were evaluated. </LI> <LI> Physiological and subjective responses under the cold exposure were maintained or improved even after the alternating exposure program. </LI> <LI> The possibility of improvement in cold tolerance under cold and heat exposure in daily lives was found out. </LI> </UL> </P>

Changes of Physiological and Perceptual Responses after a 14-day Cold-interrupted Heat Exposure

Joonhee Park,Sora Shin,Joo-Young Lee 한국생활환경학회 2019 한국생활환경학회지 Vol.26 No.4

Heat exposures induce heat acclimation but it needs to investigate whether or not heat acclimation occurs when the heat exposure is conducted along with cold exposure. We hypothesized that short-term heat acclimation through the cold-interrupted heat exposure would occur even though the heat exposure is intermittently interrupted by cold exposure. The heat exposure program consisted of a 2-h treadmill exercise in an environment (30℃ in Ta and 60%RH in air humidity, afternoon session) for 14 consecutive days. A 2-hour cold exposure was conducted in a cold environment (10℃ in Ta and 40%RH in air humidity, morning session) before heat exposure program each day. Eight male subjects participated in a heat tolerance test (afternoon session) before (PRE) and after (POST) the 14-day cold-interrupted heat exposure program. Both changes of mean skin and mean body temperatures were lower in POST than those in PRE (P<0.05) while no statistical difference was found for change in rectal temperature between PRE and POST. There were no statistical differences in heart rate, systolic and diastolic blood pressures, and local sweat rates between PRE and POST. Subjects felt less hot, less uncomfortable, and less wet on their hands in POST when compared to those in PRE during the heat tolerance test (P<0.05). These results showed the possibility that heat acclimation was interfered with repeated cold exposures.

Relationships of self-identified cold tolerance and cold-induced vasodilatation in the finger

Park, Joonhee,Lee, Joo-Young Springer-Verlag 2016 International journal of biometeorology Vol.60 No.4

<P>This study was conducted to investigate relationships of self-identified cold tolerance and cold-induced vasodilatation (CIVD) in the finger. Nine males and 34 females participated in the following 2 tests: a CIVD test and a self-reported survey. The CIVD test was conducted 30-min cold-water immersion (3.8 +/- A 0.3 A degrees C) of the middle finger at an air temperature of 27.9 +/- A 0.1 A degrees C. The self-reported questionnaire consisted of 28 questions about whole and local body cold and heat tolerances. By a cluster analysis on the survey results, the participants were divided into two groups: high self-identified cold tolerance (HSCT, n = 25) and low self-identified cold tolerance (LSCT, n = 18). LSCT had lower self-identified cold tolerance (P < 0.001), preferred hot thermal stimulation (P = 0.006), and wore heavier clothing during daily life (P < 0.001) than HSCT. LSCT had significantly lower maximal finger temperatures (T (max)) (P = 0.040), smaller amplitude (P = 0.029), and delayed onset time of CIVD (P = 0.080) when compared to HSCT. Some questions examining the self-identified cold or heat tolerance had relationships with cold tolerance index, T (max), and amplitude (P < 0.1). These results indicate that self-identified cold tolerance classified through a standardized survey could be a good index to predict physiological cold tolerance.</P>

CLOTHING & TEXTILES : Layering Effects on Clothing Microclimate, Clothing Insulation and Physiological Responses

( Joonhee Park ),( Shinjung Yoo ) 대한가정학회 2013 International Journal of Human Ecology Vol.14 No.2

This study investigated the relationship of clothingmicroclimate and physiological responses in order toexamine the layering effects on the clothing microclimate asan index to predict clothing thermal insulation (Icl).Experiments were conducted in a 15oC environment on sixphysically active males. Increased clothing layers resulted inhigher mean temperature inside the clothing (Tcl) and Icl. The Icl had a high correlation with: Tcl (r=0.556), thedifference between the innermost surface temperature andthe outermost surface temperature at the chest (DST)(r=0.549) and the temperature inside clothing at theabdomen (r=0.478). Tcl had the highest correlation withthe temperature inside clothing at the abdomen (r=0.889). Tcl also had the highest correlation with sk (r=0.860).The results showed that the relationship between Icl and Tcl was linear (p<.01). Thermal comfort had a negativecorrelation with Tcl-thigh (r=-0.411) and Tcl (r=-0.323)(p<.01.)

Whole-body cold tolerance in older Korean female divers “haenyeo” during cold air exposure: effects of repetitive cold exposure and aging

Park, Joonhee,Kim, Siyeon,Kim, Do-Hee,Cha, Seongwon,Lee, Joo-Young Springer-Verlag 2018 International journal of biometeorology Vol.62 No.4

Effects of Contralateral Hand Immersion in Hot Water on Physiological Responses and Subjective Perceptions during Finger Cold-induced Vasodilatation Test

Joonhee Park,Young-Joon Jang,Joo-Young Lee 한국생활환경학회 2017 한국생활환경학회지 Vol.24 No.2

This study investigated cold-induced vasodilatation (CIVD) responses in the finger during contralateral hand heating to suggest preventive countermeasures for workers in cold. Thirty three students (23.9 ± 2.4 yr in age, 1.65 ± 0.08 m in height, 55.2 ± 10.5 kg in body mass; 28 females and 5 males) participated in two trials: left middle finger immersion in cold water (4oC) (FC) and right hand immersion in hot water (42oC) combined with FC (FCHH). Both tests consisted of a 10-min rest, 30-min immersion, and 20-min recovery. FCHH had higher mean left middle temperatures compared to FC during immersion and recovery (P<0.05). FCHH had higher Tmin, Tmax, Tmean, amplitude, and resistance index for frostbite when compared to FC (P<0.05). During the immersion and recovery periods, chest and foot temperatures were higher and lower, respectively, in FC than those in FCHH (P<0.05). Heart rate during immersion was higher in FCHH when compared to FC (P<0.05). In summary, the contralateral hand heating during the finger CIVD test resulted in pronounced CIVD responses, and also affected cardiovascular responses. The wearing of at least one glove during cold exposure can be helpful for workers’ comfort and performance.

Layering Effects on Clothing Microclimate, Clothing Insulation and Physiological Responses

Park, Joonhee,Yoo, Shinjung The Korean Home Economics Association 2013 International Journal of Human Ecology Vol.14 No.2

This study investigated the relationship of clothing microclimate and physiological responses in order to examine the layering effects on the clothing microclimate as an index to predict clothing thermal insulation ($I_{cl}$). Experiments were conducted in a $15^{\circ}C$ environment on six physically active males. Increased clothing layers resulted in higher mean temperature inside the clothing ($\bar{T}_{cl}$) and $I_{cl}$. The $I_{cl}$ had a high correlation with: $\bar{T}_{cl}$ (r = 0.556), the difference between the innermost surface temperature and the outermost surface temperature at the chest (DST) (r = 0.549) and the temperature inside clothing at the abdomen (r = 0.478). $\bar{T}_{cl}$ had the highest correlation with the temperature inside clothing at the abdomen (r = 0.889). $\bar{T}_{cl}$ also had the highest correlation with $\bar{T}_{sk}$ (r = 0.860). The results showed that the relationship between $I_{cl}$ and $\bar{T}_{cl}$ was linear (p < .01). Thermal comfort had a negative correlation with $\bar{T}_{cl-thigh}$ (r=-0.411) and $\bar{T}_{cl}$ (r = -0.323) (p < .01.)

Body Mapping of Subjectively Assessed Sweat Sensation and Thermal Comfort in Cycling Wear

Joonhee Park,Shinjung Yoo(유신정) 한국생활환경학회 2011 한국생활환경학회지 Vol.18 No.6

자전거 이용은 에너지 기후 시대를 맞이한 오늘날, 녹색성장의 기초방안으로 거론되고 있으며, 레저 활동 및 건강 증진의 관점에서도 주목받고 있다. 그러나 사이클 의복에 대한 온열생리반응 및 주관적 감각 측면의 연구는 부족한 실정이다. 이에 본 연구에서는 286명의 정기적인 자전거 이용자를 대상으로 사이클링 시 주관적으로 인지되는 계절별 서열 스트레스, 발한, 불쾌감의 정도 등에 대해서 바디맵핑 기법을 적용한 설문지를 이용하여 조사하였다. 그 결과, 응답자들은 사이클 의복에 있어서 가장 불쾌감을 느끼는 측면은 땀처리 문제라고 하였다. 발한에 따른 불쾌감은 심지어 겨울에도 높았으며, 모든 계절에 있어서 사이클링 시 쾌적감 향상을 위해서는 사이클 의복의 등, 엉덩이샅, 겨드랑이, 가슴 부위의 개선이 필요한 것으로 조사되었다. 특히 겨울용 사이클 의복의 경우, 등 부위에서는 땀 배출이 효과적일 수 있도록 환기 성능(ventilation)이 고려되어야 하는 한편, 가슴 부위에서는 보온성이 요구되는 등 상반되는 두 가지 성능이 동시에 고려되어져야 하는 것으로 나타났다. 본 연구 결과가 쾌적성과 발한 관리 성능을 개선한 고성능의 사이클 의복의 디자인 개발에 도움이 되기를 기대한다. In the energy-conservation era, cycling is receiving worldwide attention and enjoying increased popularity. However, comprehensive studies related to subjective and objective thermophysiological responses for cycling wear are lacking. This study was conducted to investigate subjectively the thermal burden, sweat perception, and thermal comfort of various body parts during cycling. The questionnaire consisted of questions on perceived thermal feeling, sweating sensation, and consequent discomfort of different body parts while cycling during different seasons. Korean bicyclists (n = 286) participated to the survey. The results were as follows. The respondents reported sweat management as the most uncomfortable aspect of cycling wear. The discomfort due to sweating was dominant even in winter and indicated that clothing for the back, buttocks/crotch, axilla, and chest should be improved for better comfort. For winter wear, the results suggested the need for improved back ventilation and chest insulation. The findings provide practical insight into novel product designs and the development of high-performance cycling wear for better thermophysiological comfort and sweat management.