Publications by authors named "Seong-Hee Ko"

Heat stress due to climate warming can significantly affect the synthesis of sex hormones in male adolescents, which can impair the ability of the hypothalamus to secrete gonadotropin-releasing hormone on the hypothalamic-pituitary-gonadal axis, which leads to a decrease in luteinizing hormone and follicle-stimulating hormone, which ultimately negatively affects spermatogenesis and testosterone synthesis. For optimal spermatogenesis, the testicular temperature should be 2-6 °C lower than body temperature. Heat stress directly affects the testes, damaging them and reducing testosterone synthesis.

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Aging and menopause are associated with oxidative stress and inflammation. Here, we evaluated the antioxidant properties of pumpkin ( L.) seed extract and assessed its ameliorative effects on aging- and menopause-related diseases using Saos-2 cells and ovariectomized rats.

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A variety of metabolic disorders are associated with a decrease in estradiol (E2) during natural or surgical menopause. Postmenopausal women are prone to excessive fat accumulation in skeletal muscle and adipose tissue due to the loss of E2 via abnormalities in lipid metabolism and serum lipid levels. In skeletal muscle and adipose tissue, genes related to energy metabolism and fatty acid oxidation, such as those encoding peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) and estrogen-related receptor alpha (ERRα), are downregulated, leading to increased fat synthesis and lipid metabolite accumulation.

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The intestine and skin provide crucial protection against the external environment. Strengthening the epithelial barrier function of these organs is critical for maintaining homeostasis against inflammatory stimuli. Recent studies suggest that polar marine algae are a promising bioactive resource because of their adaptation to extreme environments.

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Article Synopsis
  • ucOCN plays a significant role in regulating inflammation and energy metabolism, showing an inverse relationship with chronic inflammatory diseases.
  • The study investigates ucOCN's effects on inflammation in myoblasts, revealing that it suppresses inflammatory cytokines like IL-1β and inhibits NF-κB activation in response to TNF-α.
  • Findings indicate that GPRC6A is not the receptor for ucOCN's anti-inflammatory effects, as its knockdown still results in decreased IL-1β expression, suggesting other membrane or cytoplasmic targets for ucOCN interactions.
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Aging women experience hormonal changes, such as decreased estrogen and increased circulating androgen, due to natural or surgical menopause. These hormonal changes make postmenopausal women vulnerable to body composition changes, muscle loss, and abdominal obesity; with a sedentary lifestyle, these changes affect overall energy expenditure and basal metabolic rate. In addition, fat redistribution due to hormonal changes leads to changes in body shape.

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Menopause is clinically diagnosed as a condition when a woman has not menstruated for one year. During the menopausal transition period, there is an emergence of various lipid metabolic disorders due to hormonal changes, such as decreased levels of estrogens and increased levels of circulating androgens; these may lead to the development of metabolic syndromes including cardiovascular diseases and type 2 diabetes. Dysregulation of lipid metabolism affects the body fat mass, fat-free mass, fatty acid metabolism, and various aspects of energy metabolism, such as basal metabolic ratio, adiposity, and obesity.

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Sclerostin decreases bone mass by antagonizing the Wnt signaling pathway. We examined whether obesity-induced bone loss is associated with the expression of sclerostin. Five-week-old male mice were assigned to one of two groups (n = 10 each) and fed either a control diet (10% kcal from fat; CON) or a high-fat diet (60% kcal from fat; HF) for 12 weeks.

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Metabolic syndrome describes a group of clinical features that together increase the incidence of coronary artery disease, stroke and type 2 diabetes. Insulin resistance is a major risk factor for developing metabolic syndrome. A chronic state of inflammation accompanies the accumulation of surplus lipids in adipose and liver tissue, frequently involved in insulin resistance.

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Artificial digestive solution based on pepsin is essential for collecting metacercariae from fish. To promote the enzymatic reactivity of pepsin, the pH of the solution has to be adjusted to pH 1.0-2.

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Background: Skin is uniquely vulnerable to damage caused by reactive oxygen species (ROS), which are most commonly produced in response to ultraviolet (UV) light. ROS generated at injury sites play an important role in modulating the inflammatory response. Besides inhibiting Rac, 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dG) has also shown notable antioxidant action.

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Sulindac analogs represent one of the most efficacious groups of NSAIDs reducing the risk of colon cancer. Recent studies have shown that sulindac sulfide, a sulindac analog effective at lower doses compared to its parent compound, triggers the death receptor (DR)5-dependent extrinsic apoptotic pathway. Induction of apoptosis via activation of the DR-mediated pathway would be an ideal therapeutic strategy to eliminate cancer cells.

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Article Synopsis
  • * Rats were treated with different doses of SAM, which resulted in a significant decrease in vascular smooth muscle cell (VSMC) proliferation and an increase in cell death, leading to a lower intima-to-media ratio post-injury.
  • * SAM treatment also influenced inflammatory markers and oxidative stress, suggesting it may have protective effects against restenosis in type 2 diabetes by modulating VSMC behavior and reducing inflammatory responses.
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Zeolite 4A, synthetic silicate, has been shown to exhibit diverse biological activities such as anti-cancer and anti-oxidant activity. In the present study, we report that the zeolite 4A may improve skin-whitening. We found that zeolite 4A inhibited melanin production in a dose-dependent manner, which has not cytotoxicity.

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Many herbs have been used as therapeutics in Korean traditional medicine. In view of their clinical indications, anti-oxidant activity may contribute to their pharmacological effects. However, anti-oxidant information on these plants has not been available.

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Using an established high-performance liquid chromatography (HPLC) method based on anion exchange chromatography, fraction collection, and electrochemical detection, the oxidative DNA damage marker 8-hydroxy-2'-deoxyguanosine (8-OH-dG) can be analyzed rapidly and precisely in human urine samples. In addition, by ultraviolet (UV) detection, it was shown recently that it is possible to simultaneously analyze creatinine and 7-methylguanine (m(7)Gua), an RNA degradation product, in urine. By adding a fluorescence detector to the HPLC system, we now report that it is also possible to detect pteridins such as neopterin and biopterin.

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Cyclooxygenase-2 (COX-2), an enzyme that catalyzes the synthesis of prostaglandins, is made inducible by various stimuli such as inflammation. Although COX-2 is commonly overexpressed in a variety of premalignant and malignant conditions including oral leukoplakia and squamous cell carcinoma, relatively little research has compared the effects of various COX-2 inhibitors (celecoxib, NS-398, nimesulide and meloxicam). Therefore, we investigated the effects of four different selective COX-2 inhibitors on the growth of KB cells, derived from oral squamous cell carcinoma (OSCC) and its mechanisms.

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Recently, we observed that 8-hydroxyguanosine triphosphate and 8-hydroxy-2'-deoxyguanosine (oh(8)dG) inactivate Rac and consequently down-regulate the Rac-linked NADPH oxidase, iNOS, and Cox2. Based on these observations, we tested whether oh(8)dG has anti-inflammatory activity in vivo in lipopolysaccharide (LPS)-treated mice. LPS (1 mg/kg, ip)-treated mice exhibit marked inflammatory responses, including increases in proinflammatory cytokines (TNF-alpha, IL-6, IL-18, and IL-12p70) in serum and infiltration of neutrophils, increased translocation of NF-kappaB p50 from the cytosol to the nucleus, and phosphorylation of c-Jun in lung tissues.

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It was reported that in rats with water deprivation for 72 h with food (dehydration rat model), the expression of CYP2E1 was 3-fold induced with an increase in mRNA level and glucose supplementation instead of food during 72-h water deprivation (dehydration rat model with glucose supplementation) inhibited the CYP2E1 induction in dehydration rat model. It was also reported that chlorzoxazone (CZX) is metabolized to 6-hydroxychlorzoxazone (OH-CZX) mainly via CYP2E1 in rats. Hence, the effects of glucose supplementation on the pharmacokinetics of CZX and OH-CZX were investigated after intravenous administration of CZX at a dose of 25 mg/kg to control male Sprague-Dawley rats and dehydration rat model and dehydration rat model with glucose supplementation.

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Oxidative stress in humans is associated with damage to DNA, proteins, and biological membranes. Oxidative stress, which often arises as a result of an imbalance in the human antioxidant status, has been implicated in aging and a number of human diseases such as cancer, atherosclerosis, and rheumatoid arthritis. This study was performed to test the hypothesis that the consumption of fruit juices may improve antioxidant status in human plasma.

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The pharmacokinetics and pharmacodynamics of torasemide were evaluated after intravenous administration of the same total dose of torasemide at a dose of 1mg/kg to rabbits with different infusion times, 1 min (treatment I), 30 min (treatment II) and 2 h (treatment III). The loss of water and electrolytes in urine induced by torasemide was immediately replaced with infusion of an equal volume of lactated Ringer's solution. All the pharmacokinetic parameters of torasemide, such as total area under the plasma concentration-time curve from time zero to time infinity (AUC), total body clearance (CL), apparent volume of distribution at steady state (Vss), terminal half-life and mean residence time (MRT), were independent of infusion times.

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The effects of differences in the rate and composition of intravenous fluid replacement for urine loss on the pharmacokinetics and pharmacodynamics of torasemide were evaluated in rabbits. Each rabbit received 2-h constant intravenous infusion of 1 mg kg(-1) torasemide with 0% replacement (treatment 1, n=6), 50% replacement (treatment 2, n=9), 100% replacement with lactated Ringer's solution (treatment 3, n=8), and 100% replacement with 5% dextrose in water (treatment 4, n=6). Total body (4.

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Osteoprotegerin (OPG), a member of the tumor necrosis factor receptor superfamily, is known to inhibit osteoclastogenesis by acting as a soluble decoy receptor for the receptor activator of NF-kappaB ligand (RANKL). We report the presence of OPG on the membrane of osteoclasts and the possibility of the direct action of OPG on them. Highly pure osteoclast precursors were isolated from mouse long bones and induced to differentiate into mature osteoclasts by M-CSF and soluble RANKL (sRANKL).

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