• The Korean Journal of Physiology
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• 제28권2호
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• pp.143-150
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• 1994

The whole-cell mode of the patch clamp technique was used to study $Ca^{2+}-activated\;Cl^-\;current$ $(I_{Cl_{Ca}})$ in gastric antral myocytes. Extracellular application of caffeine evoked $Ca^{2+}-activated\;current$. In order to isolate the chloride current from background current, all known systems were blocked with specific blockers. The current-voltage relationship of caffeine-induced current showed outward rectification and it reversed at around $E_{Cl^-}$. The shift of reversal potential upon the alteration of external and internal chloride concentrations was well fitted with results which were calculated by the Nernst equation. Extracellular addition of N-phenylanthranilic acid and niflumic acid which are known anion channel blockers abolished the caffeine induced current. Intracellular application of a high concentration of EGTA also abolished this current. Application of c-AMP, c-GMP, heparin, or $AIF^-_4$ made no remarkable changes to this current. Sodium replacement with the impermeable cation N-methylglucamine or with $Cd^{2+}$ rarely affected this current. From the above results it is suggested that the caffeine induced current was a $Cl^-$ current and it was activated by intracellular $Ca^{2+}$.

• Animal cells and systems
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• 제15권3호
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• pp.203-210
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• 2011

In the present study, we examined the effects of caffeine on food intake and body weight, and pro-opiomelanocortin (POMC) and agouti-related protein (AgRP) expression in the hypothalamus. Rats were administered intraperitoneally with 100 mg/kg caffeine (a high, non-toxic dose) or saline during the light phase. Intraperitoneal administration of caffeine induced a significant reduction in food intake and body weight 12 hr after treatment. In addition, POMC expression was significantly increased and AgRP expression was decreased in the arcuate nucleus (Arc) after caffeine treatment. These results demonstrate that administration of caffeine up-regulates POMC expression and down-regulates AgRP expression in the Arc, suggesting that the activation of the hypothalamic POMC neurons and inhibition of the AgRP neurons might play a role in the regulation of food intake and body weight by caffeine.

• 동의생리병리학회지
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• 제30권2호
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• pp.88-94
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• 2016

The study was carried out to examine the anti-obesity effects of 40% ethanol extract from green tea seed (GS) and quantitative determination of caffeine as its major compound. The specificity was satisfied with retention time and UV spectrum by analysis of caffeine using HPLC and comparison with standard compound. It showed a high linearity in the calibration curve with a coefficient of correlation (R²) of 0.9974. The amount of caffeine in GS was about 4.649 mg/g (0.465%) in the three times analysis, and relative standard deviation (RSD) was less than 0.452% by the validated method. The anti-obesity effects of GS were evaluated by using Oil Red O staining in 3T3-L1 adipocytes and body weight, visceral fat and lipid profiles in high fat diet (HFD)-induced C57BL/6 obese mice. Our results indicated that treatment with GS dose-dependently decreased lipid accumulation contents (p<0.001). Moreover, after oral administration for 30 days feeding with HFD-induced obses mice, GS (100 and 300 mg/kg/day) produced a significant decrease in serum total cholesterol (TC), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and visceral fat. Thus, the result of this study indicate that the GS may be a useful resource for the management of obesity.

• 동아시아식생활학회지
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• 제24권3호
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• pp.407-420
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• 2014

본 연구는 대학생의 고카페인 에너지음료 실태 조사를 통해서 무분별한 고카페인 에너지음료 섭취에 대한 문제점을 해결하고자 서울 지역의 대학생 300명을 대상으로 고카페인 에너지음료 섭취 실태에 대해 조사하였으며, 조사 결과는 다음과 같다. 조사 대상자의 성별은 남성은 35%, 여성은 65%인 것으로 나타났고, 학년으로 대학생 4학년이 38.3% 가장 많았으며, 한 달 평균 용돈은 50만원 이상 55.0%로 가장 많았고, 한 달 음료 구입비 73.0% 가장 많았다. 고카페인 에너지음료 섭취 경험은 전체 학생의 68.7%가 에너지음료를 마셔본 경험이 있었으며, 여성(63.6%)에 비해 남성(78.1%)이 에너지음료를 섭취한 경험이 높은 것으로 나타났다(p<0.05). 고카페인 에너지음료는 주로 공부할 때 마시는 학생이 가장 많았으며, 성별에 상관없이 공부할 때에 가장 많이 마시는 것으로 나타났다(p<0.05). 고카페인 에너지음료의 섭취 횟수는 1~6회/년 미만이 가장 많았고, 여성은 남성에 비해 거의 마시지 않는다는 응답이 많았다(p<0.05). 고카페인 에너지음료 구입 장소로 편의점이 가장 많았으며, 고카페인 에너지음료에 대한 정보 경로는 TV나 라디오, 신문, 잡지 등의 광고를 통해 알게 된 학생이 가장 많았다. 고카페인 에너지음료 구매 시 영향 요인으로 '맛'이 가장 크게 영향을 미친다는 반응을 보였다. 고카페인 에너지음료 섭취 시 부작용과 문제점에서 에너지음료 섭취 후 심장 두근거림을 부작용으로 느낀 경우가 가장 많았고, 고카페인 에너지음료 섭취 시 문제점으로 중독 증상이라고 가장 많이 응답하였다. 이상의 본 연구 결과를 토대로 고카페인 에너지음료의 섭취에 다음과 같이 제안하고자 한다. 최근 들어 에너지음료 섭취가 늘어나고 있는 대학생들이 에너지음료가 고카페인 음료라는 것을 인지하고 있으면서도 공부를 위해서 이들 고카페인 에너지음료를 무분별하게 과량 섭취하는 것이 문제이므로 카페인 과량 섭취 시 부작용을 인식시키고, 올바른 에너지음료에 대한 구매와 구입법, 음용법 등을 알려서 계층별 카페인의 1일 섭취 허용량만큼만 섭취할 수 있도록 해야 한다. 또한 에너지음료의 카페인 함유량을 제한하고 효율적인 규제방안이 반드시 필요할 것으로 사료된다. 현재 정부에서는 카페인 과량 섭취의 위험성을 인식하고 '식품 표시법'을 개정하여 '카페인 함유'라는 문구와 함께 고카페인 음료에 대해서는 카페인 함유량 표시를 의무화하고 있으며, 올해 1월 말부터 '어린이 식생활 안전관리 특별법'을 개정하여 학교내 매점이나 어린이 기호 식품 우수 판매 업소에서 에너지음료를 판매하지 못하게 하고, 특정시간대의 방송광고도 제한하도록 하고 있지만, 소비자 단체와 전문가들을 중심으로 그 실효성에 대해서는 의문을 제기하고 있는 경우가 많으므로, 카페인 함유량 표시 의무화 외에도 정부 차원의 엄격한 규제 및 관리 방안을 통해서 고카페인 에너지음료의 카페인 함유량을 제한할 수 있도록 하는 효율적인 규제방안이 반드시 필요하다. 특히 고카페인 에너지음료의 소비층이 청소년에서 어린이와 대학생, 직장인으로 확대되고 있는 현실에서 일부 취약계층에 대한 에너지음료 판매 제한뿐만이 아니라, 대학생이나 성인들을 대상으로 한 술집 등에서의 판매 증가와 주류와 섞어 마시는 등의 잘못된 음용 방법 개선을 위해 판매 장소와 판매 품목 제한과 같은 정부 차원의 보다 효과적인 규제 및 관리 방안을 마련해야 할 것이다. 특히 한국소비자원의 조사 결과에서와 같이 에너지음료를 섭취한 적이 있는 대학생 중에 상당수가 알코올과 섞어서 마실 정도로 이러한 잘못된 음주 습관이 대학가의 음주 문화로 자립잡고 있으므로, 잘못된 음주 습관으로 인한 위험성을 적극적으로 알릴 필요가 있다. 또한 에너지음료와 같은 기호식품의 소비에 있어서는 소비자의 알 권리를 인식하고, 합리적으로 제품을 선택할 수 있도록 대학생들을 대상으로 한 식생활 교육이 자연스럽게 이루어져야 할 필요성도 있겠다.

• The Korean Journal of Physiology and Pharmacology
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• 제5권6호
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• pp.487-494
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• 2001

During depolarization, extrusion of $Ca^{2+}$ from sarcoplasmic reticulum through forward-mode $Na^+-Ca^{2+}$ exchange was studied in the rat ventricular myocytes patch-clamped in whole-cell configuration. In order to confine the $Ca^{2+}$ responses in a micro-domain by limiting the $Ca^{2+}$ diffusion time, rat ventricular myocytes were dialyzed with high (14 mM) EGTA. $K^+$ current was suppressed by substituting KCl with 105 mM CsCl and 20 mM TEA in the pipette filling solution and by omitting KCl in the external Tyrode solution. $Cl^-$ current was suppressed by adding 0.1 mM DIDS in the external Tyrode solution. During stimulation roughly mimicking action potential, the initial outward current was converted into inward current, $47{\pm}1%$ of which was suppressed by 0.1 mM $CdCl_2.$ 10 mM caffeine increased the remaining inward current after $CdCl_2$ in a cAMP-dependent manner. This caffeine-induced inward current was blocked by $1\;{\mu}M$ ryanodine, $10\;{\mu}M$ thapsigargin, 5 mM $NiCl_2,$ or by $Na^+\;and\;Ca^{2+}$ omission, but not by $0.1\;{\mu}M$ isoproterenol. The $I{\sim}V$ relationship of the caffeine-induced current elicited inward current from -45 mV to +3 mV with the peak at -25 mV. Taken together, it is concluded that, during activation of the rat ventricular myocyte, forward-mode $Na^+-Ca^{2+}$ exchange extrudes a fraction of $Ca^{2+}$ released from sarcoplasmic reticulum mainly by voltage-sensitive release mechanism in a micro-domain in the t-tubule, which is functionally separable from global $Ca^{2+}{_i}$ by EGTA.

• 한국식품영양학회지
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• 제31권3호
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• pp.416-424
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• 2018

The physiologically advantageous aspects of green tea have been identified recently and green tea has been a favorite drink of many people. Due to the increased awareness of green tea's positive effects on human health, the demand for foods containing green tea has increased. This has led to the development of diverse green tea-related beverages; thereby many companies in Korea have put a wide variety of manufactured green tea beverages on the market. However, the components within green tea beverages have not been examined in Korea yet. In this study, we investigated the contents of the physiologically functional materials found in green tea, such as catechin, catechin gallate, epicatechin, epicatechin gallate, epigallocatecin gallate, gallocatechin gallate and caffeine. Fifty-six green tea products purchased from the local grocery stores and cafes were analyzed using high performance liquid chromatography (HPLC) analysis. As a result, all tested products contained catechin and caffeine, although the amount of each component was largely different. The total amount of catechin derivatives in the manufactured green tea beverages purchased from cafes was 263.17 mg/L, while they were 61.99 mg/L in the beverages purchased from the local grocery stores. And, to the almost samples the amount of caffeine was proportional to the amount of catechin.

• 대한지역사회영양학회지
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• 제23권4호
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• pp.289-301
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• 2018

Objectives: The aim of this study was to examine the current status of consumption of energy drinks among college students and investigate the effects of general environmental factors, health behavior factors, caffeine knowledge levels, and perceived stress levels on consumption of energy drinks. Methods: A survey was conducted among a total of 479 college students in Gwangju, using self-administered questionnaires. The questionnaire consisted of items about general environmental factors, health behavior, caffeine knowledge, perceived stress, and energy drink consumption behaviors. Results: 69.1% of participants experienced consumption of energy drinks, and specifically 82.8% of male students and 54.1% of female students experienced consumption of energy drinks (p<0.001). The reasons for drinking energy drinks were found to be recovery from fatigue, curiosity, taste, habit, thirst relief, and stress relief. In addition, 40.7% of participants experienced drinking energy drinks mixed with alcohol, and specifically 48.6% of male students and 27.4% of female students reported drinking energy drinks with alcohol (p<0.001). Moreover, 51.5% of participants responded that they experienced the effects of energy drinks, 31.9% reported experiencing adverse effects, and 41.1% were found to perceive the health risks. As a result of the assessment of caffeine knowledge, the participants showed a high level of knowledge of the arousal effect (77.7%) and the concentration increasing effect (70.8%) of caffeine, whereas they exhibited a low level of understanding of the health problems due to caffeine (32.6%) and adequate caffeine intake levels (24.4%). The higher levels of consumption experience of energy drinks was associated with higher body mass indexes (BMI) (p<0.01), higher academic years (p<0.01), lower levels of interest in health (p<0.05), smoking (p<0.001), alcohol consumption (p<0.05), and higher levels of perceived stress (p<0.05). Conclusions: The risk groups related to consumption of energy drinks among college students were identified as male students rather than female students, students in the third or fourth year of study associated with increased stress levels, and students with negative health behaviors. Therefore, support for diverse health and nutrition education for college students is required along with the improvement of internal and external environments of schools in order for college students to manage increased stress levels due to the schoolwork and preparation for employment and maintain positive health behaviors.

• Bulletin of the Korean Chemical Society
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• 제27권1호
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• pp.71-76
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• 2006

Porous polymer monolithic columns were prepared by the direct free radical copolymerization of methacrylic acid and ethylene glycol dimethacrylate within the confines of a chromatographic column in the presence of toluene-dodecanol as a porogenic solvent. The separation characteristics of the monolithic columns were tested by a homologous series of xanthine derivatives, theophylline and caffeine. The effects of the polymerization mixture composition and polymerization condition, mobile phase composition, flow rate and temperature on the retention times and separation efficiencies were investigated. The results showed that the selection of correct porogenic solvents and appropriate polymerization conditions are crucial for the preparation of the monolithic stationary phases. The separation efficiency was only extremely weakly dependent on flow rate and temperatures. Hydrogen-bonding interaction played an important role in the retention and separation. Compared with conventional particle columns, the monolithic column exhibited good stability, ease of regeneration, high separation efficiency and fast analysis.

• 한국병원경영학회지
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• 제24권2호
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• pp.12-22
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• 2019

Purposes: The purpose of this study was to examine the association between risk behaviors and smoking in Korean adolescents. Methods: This study used data from online survey of youth health behavior in 2017. Data from a total of 54,411 people (27,139 male, 27,272 female) were included in the analysis. chi-square test, simple logistic regression, multiple logistic regression were performed using SAS 9.4. Findings: Multiple logistic regression analysis showed that risk behaviors such as drinking alcohol experience, sexual experience, drug use experience and high caffeine energy drinks intake experience had a significant effect on smoking. Adolescents with drinking experience were more likely to smoking than those who had no experience(OR=8.58, 95% CI: 7.67~9.60). Adolescents with sexual experience were more likely to smoking than those who had no experience(OR=4.47, 95% CI: 3.91~5.11). Adolescents with drug use experience were more likely to smoking than those who had no experience(OR=2.32, 95% CI: 1.63~3.32). Also, adolescents with high-caffeine energy drinks intake experience were more likely to smoking than those who had no experience(OR=1.37, 95% CI: 1.23~1.53). Practical Implications: All the risk behaviors were significantly associated with smoking rates. Results of this study suggest that physicians and health workers in medical institutions and health centers should simultaneously serve education and consultation for the smoking cessation as well as for the prevention of risk behaviors.

• 한국가축번식학회지
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• 제20권1호
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• pp.63-69
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• 1996

Bovine immature oocytes cultured for various times in TC-199 medium were inseminated with frozne-thawed spermatozoa in TC-199 medium supplemented with caffeine(5mM) and heparin(10$\mu\textrm{g}$/ml). Sperm penetraton was possible in oocytes at any stage of maturation, but penetration rates were lower in oocytes inseminated 0~16h (60~76%) than 20h (98%) after culture. Formation of male and female pronuclei were first observed in oocytes inseminated 8h after cultrue. Formation of male and female pronuclei were first observed in oocytes inseminated 8h after culture. The proportions of polyspermy were high(50~76%) in oocytes inseminated at any stage of maturation. Sperm penetration into oocytes at the GV stage started at 8h after insemination and the penetration rates gradually increased as time after insemination proceeds. The proportion(35%) of oocytes matured beyond metaphase-II 20h after sperm-oocytes incubation was low. When oocytes were incubated without spermatozoa in TC-199 medium, maturation rates were significantly higher (P<0.001) in those without(45 and 84% for 16 and 20 h) than with (0 and 36% for 16 and 20 h) caffeine and heparin. These results indicate that TC-199 medium with caffeine and heparin is not suitable for maturation and fertilization of immature oocytes and may inhibit male pronuclear formation in the cytoplasm.