Hyon Park

Prof. Hyon Park

orcid

Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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LJLae-Guen Jang
Lae-Guen Jang
GCGeunhoon Choi
Geunhoon Choi
Sung-Woo KimSung-Woo Kim
Sung-Woo Kim
BKByung-Yong Kim
Byung-Yong Kim
SLSunghee Lee
Sunghee Lee
HPHyon Park
Hyon Park
Recently, gut microbiota have been studied extensively for health promotion, disease prevention, disease treatment, and exercise performance. It is recommended that athletes avoid dietary fiber and resistant starch to promote gastric emptying and reduce gastrointestinal distress during exercise, but this diet may reduce microbial diversity and compromise the health of the athlete’s gut microbiota. This study compared fecal microbiota characteristics using high-throughput sequencing among healthy sedentary men (as controls), bodybuilders, and distance runners, as well as the relationships between microbiota characteristics, body composition, and nutritional status. Body composition was measured using DXA, and physical activity level was assessed using IPAQ. Dietary intake was analyzed with the computerized nutritional evaluation program. The DNA of fecal samples was extracted and it was sequenced for the analysis of gut microbial diversity through bioinformatics cloud platform. We showed that exercise type was associated with athlete diet patterns (bodybuilders: high protein, high fat, low carbohydrate, and low dietary fiber diet; distance runners: low carbohydrate and low dietary fiber diet). However, athlete type did not differ in regard to gut microbiota alpha and beta diversity. Athlete type was significantly associated with the relative abundance of gut microbiota at the genus and species level: Faecalibacterium, Sutterella, Clostridium, Haemophilus, and Eisenbergiella were the highest (p < 0.05) in bodybuilders, while Bifidobacterium and Parasutterella were the lowest (p < 0.05). At the species level, intestinal beneficial bacteria widely used as probiotics (Bifidobacterium adolescentis group, Bifidobacterium longum group, Lactobacillus sakei group) and those producing short chain fatty acids (Blautia wexlerae, Eubacterium hallii) were the lowest in bodybuilders and the highest in controls. In addition, aerobic or resistance exercise training with an unbalanced intake of macronutrients and low intake of dietary fiber led to similar diversity of gut microbiota. Specifically, daily protein intake was negatively correlated with operation taxonomic unit (r = − 0.53, p < 0.05), ACE (r = − 0.51, p < 0.05), and Shannon index (r = − 0.64, p < 0.01) in distance runners.. Results suggest that high-protein diets may have a negative impact on gut microbiota diversity for athletes, while athletes in resistance sports that carry out the high protein low carbohydrates diet demonstrate a decrease in short chain fatty acid-producing commensal bacteria.

13 December 2018 in Plant Physiology
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SMSunok Moon
Sunok Moon
LCLae-Hyeon Cho
Lae-Hyeon Cho
YKYu-Jin Kim
Yu-Jin Kim
YGYun-Shil Gho
Yun-Shil Gho
HJHo Young Jeong
Ho Young Jeong
KJKi Hong Jung
Ki Hong Jung
Root hairs are important for absorption of nutrients and water from the rhizosphere. The Root Hair Defective-Six Like (RSL) Class II family of transcription factors is expressed preferentially in root hairs and has a conserved role in root hair development in land plants. We functionally characterized the seven members of the RSL Class II subfamily in the rice (Oryza sativa) genome. In root hairs, six of these genes were preferentially expressed and four were strongly expressed. Phenotypic analysis of each mutant revealed that Os07g39940 plays a major role in root hair formation, based on observations of a short root hair phenotype in those mutants. Overexpression (OX) for each of four family members in rice resulted in an increase in the density and length of root hairs. These four members contain a transcription activation domain and are targeted to the nucleus. They interact with rice Root Hairless1 (OsRHL1), a key regulator of root hair development. When heterologously expressed in epidermal cells of Nicotiana benthamiana leaves, OsRHL1 was predominantly localized to the cytoplasm. When coexpressed with each of the four RSL Class II members, however, OsRLH1 was translocated to the nucleus. Transcriptome analysis using Os07g39940-OX plants revealed that 86 genes, including Class III peroxidases, were highly up-regulated. Furthermore, reactive oxygen species levels in the root hairs were increased in Os07g39940-OX plants but were drastically reduced in the os07g39940 and rhl1 mutants. Our results demonstrate that RSL Class II members function as essential regulators of root hair development in rice.

25 September 2020 in Nutrients
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JSJoy Son
Joy Son
LJLae-Guen Jang
Lae-Guen Jang
BKByung-Yong Kim
Byung-Yong Kim
SLSunghee Lee
Sunghee Lee
HPHyon Park
Hyon Park
Studies investigating exercise-induced gut microbiota have reported that people who exercise regularly have a healthy gut microbial environment compared with sedentary individuals. In contrast, recent studies have shown that high protein intake without dietary fiber not only offsets the positive effect of exercise on gut microbiota but also significantly lowers the relative abundance of beneficial bacteria. In this study, to resolve this conundrum and find the root cause, we decided to narrow down subjects according to diet. Almost all of the studies had subjects on an ad libitum diet, however, we wanted subjects on a simplified diet. Bodybuilders who consumed an extremely high-protein/low-carbohydrate diet were randomly assigned to a probiotics intake group (n = 8) and a placebo group (n = 7) to find the intervention effect. Probiotics, comprising Lactobacillus acidophilus, L. casei, L. helveticus, and Bifidobacterium bifidum, were consumed for 60 days. As a result, supplement intake did not lead to a positive effect on the gut microbial environment or concentration of short-chain fatty acids (SCFAs). It has been shown that probiotic intake is not as effective as ergogenic aids for athletes such as bodybuilders with extreme dietary regimens, especially protein and dietary fiber. To clarify the influence of nutrition-related factors that affect the gut microbial environment, we divided the bodybuilders (n = 28) into groups according to their protein and dietary fiber intake and compared their gut microbial environment with that of sedentary male subjects (n = 15). Based on sedentary Korean recommended dietary allowance (KRDA), the bodybuilders′ intake of protein and dietary fiber was categorized into low, proper, and excessive groups, as follows: high-protein/restricted dietary fiber (n = 12), high-protein/adequate dietary fiber (n = 10), or adequate protein/restricted dietary fiber (n = 6). We found no significant differences in gut microbial diversity or beneficial bacteria between the high-protein/restricted dietary fiber and the healthy sedentary groups. However, when either protein or dietary fiber intake met the KRDA, gut microbial diversity and the relative abundance of beneficial bacteria showed significant differences to those of healthy sedentary subjects. These results suggest that the positive effect of exercise on gut microbiota is dependent on protein and dietary fiber intake. The results also suggest that the question of adequate nutrition should be addressed before supplementation with probiotics to derive complete benefits from the intervention.

1 January 2019 in Journal of Exercise Science & Fitness
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Open access
JOJung-Woo Oh
Jung-Woo Oh
ELEun-Young Lee
Eun-Young Lee
JLJungJun Lim
JungJun Lim
SLSang-Hwa Lee
Sang-Hwa Lee
YJYu-Sun Jin
Yu-Sun Jin
YKYeon Soo Kim
Yeon Soo Kim
Background/Objective: South Korea's 2018 Report Card on Physical Activity for Children and Youth is the second comprehensive evaluation of physical activity and the sources of influence based on the 10 core indicators provided by the Active Healthy Kids Global Alliance. It will serve as an advocacy tool to promote physical activity among children and youth. Methods: Three national surveillance data (i.e., 2017 Korea Youth Risk Behavior Web-based Survey, 2016 Korea National Health and Nutrition Examination Survey, 2016 Physical Activity Promotion System) were used as main sources to evaluate the indicators. Descriptive statistics were performed to obtain prevalence estimates of physical activity-related indicators. In addition, expert opinions as well as the most recently available published or unpublished relevant sources were synthesized. Results: South Korea's 2018 Report Card, compared to the 2016 Report Card, showed favourable changes in the Active Transportation (B+), Organized Sports Participation (C), Sedentary Behaviours (D), and School (D+) indicators, while unfavourable changes were shown in Overall Physical Activity (F) and Government (D). Physical Fitness was graded as D+. In parallel with the 2016 Report Card, Active Play, Family and Peers, and Community and Environment remain ungraded due to insufficient data. Conclusions: Successes as well as gaps and research needs were identified in the 2018 Report Card. Though some indicators have shown improvement, most children and youth continue to be insufficiently physically active with overall poor grades (Average of D+). To achieve substantial improvement in all grades in future Report Cards, more institutional and governmental support and investment is needed to promote physical activity. Furthermore, effort should be made to generate data pertaining to the indicators that were ungraded. (C) 2018 The Society of Chinese Scholars on Exercise Physiology and Fitness. Published by Elsevier (Singapore) Pte Ltd.

30 September 2018 in Journal of Exercise Nutrition and Biochemistry
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Journal Article
Open access
SJSoeun Jeon
Soeun Jeon
KCKyungho Cho
Kyungho Cho
GOGina Ok
Gina Ok
SLSukho Lee
Sukho Lee
HPHyon Park
Hyon Park
The purpose of this study was to investigate the impact of weight loss practices on nutritional status, bone health, and injury history among Korean professional jockeys. Forty-three male jockeys completed a questionnaire to assess their weight loss practices. Of these, 10 jockeys were selected for in-depth assessment of their nutritional status, bone health, and injury history. The questionnaires revealed that 81.4% of jockeys lost weight every week mainly by dieting and/or exercising. None of the jockeys consumed enough food during the weight loss period. Two jockeys were diagnosed with osteopenia and one was diagnosed with osteoporosis. Only history of fracture showed a significant correlation with low bone mineral density. All jockeys had more than one injury experience throughout their career. Fracture was the most common type of injury, occurring during practice and/or competition and caused mainly by difficulties in handling the horses. Professional jockeys in Korea use extreme weight loss methods. Their repeated periods of poor nutritional intake may result in seriously low bone mineral density, which may aggravate injuries sustained during horse races. Implementation of balanced dietary programs and delivery of health education on weight management are urgently required.

10 July 2017 in Biological Rhythm Research
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Journal Article
Closed access
YSYoungju Song
Youngju Song
GCGeunhoon Choi
Geunhoon Choi
LJLaeguen Jang
Laeguen Jang
SKSeo-Woo Kim
Seo-Woo Kim
KJKi Hong Jung
Ki Hong Jung
HPHyon Park
Hyon Park
The circadian rhythm is a 24-h cycle in which cells control metabolic and physiological processes throughout the day. In this study, we compared the expression patterns of major circadian rhythm-related genes: from blood of Bmal1, Ror-α, Cry1, Per2, Per1, and Nr1d1. In addition, changes in patterns of melatonin levels were observed in 16 subjects, eight males rugby players and eight males who did not exercise regularly. Blood was collected at 6:00, 10:00, 18:00, and 22:00. Bmal1, Ror-α, Cry1, Per2 (p < 0.001), Per1 (p < 0.01), and Nr1d1 (p < 0.05) genes related to circadian rhythm was higher in rugby players than in sedentary males. However, melatonin levels were higher in sedentary males than in rugby players (p < 0.05). These results indicate that long-term exercise in athletes can increase the expression of genes related to circadian rhythm and these may have an effect on daily melatonin levels as well.