• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.3
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• pp.161-166
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• 2013

Purpose: This study was intended to perform a cephalometric comparison between the patients with and without obstructive sleep apnea (OSA). The factors influencing the OSA in the lateral cephalogram were also investigated. Methods: Fifty patients who had visited the Sleep Disorder Clinic at the Ajou University Hospital and evaluated with the polysomnograph (PSG) and cephalogram, were included in the study. The patients had the apnea-hypopnea episode over 5 times per hour (apnea-hypopnea index $[AHI]{\geq}5$) were diagnosed as OSA after the overnight PSG. To evaluate the hard and soft tissue profiles, the cephalometric radiograms were taken at the maximal intercuspation. The correlation between the patient's age, height, weight, body mass index (BMI) and AHI was inspected in the OSA and control group. The difference between the OSA and control group was evaluated (Mann-Whitney U Test). The cephalometric influencing factors to OSA were analyzed (Pearson's correlation coefficient) statistically using SPSS statistics. Results: The OSA Group had a significantly higher BMI than the control group. The mean lower facial height (ANS-Me) was longer in the OSA group; however, statistically significant difference was not detected in the anteroposterior craniofacial measurements. The distance between mandibular plane and hyoid bone of the OSA group was significantly longer than that of the control group. The hyoid position (MP-Hyoid) had a positive correlation between AHI (P<0.001). However, the measurements of oropharyngeal airway were not different between the two groups. The hypothesis, that the antero-posteriorly narrow oropharyngeal airway may aggravate the airway resistance and give rise to a higher AHI, was rejected in the study. Conclusion: We suggest that the lateral cephalogram may be utilized as a useful method to evaluate OSA. The patients with a lower hyoid position can be expected to have higher risks of OSA. However, a comprehensive intraoral inspection, including the soft palate and tonsilar hypertrophy, is emphasized, as the lateral cepahlogram cannot visualize the oropharyngeal status completely.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.196-201
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• 2005

The aim of this study was to confirm the validity of predictive equations for the calculation of basal energy expenditure (BEE). One hundred twenty female college students were participated in this study. The resting energy expenditure (REE) was measured by indirect calorimetry for 30 minutes following an 12 hour overnight fasting. Among the available equations for predict BEE, Harris-Benedict, WHO/FAO/UNU and Cunningham methods were selected. Body composition was estimated by bioelectrical impedance analysis (BIA) for the equation of predicted BEE. The mean of measured REE was 1257.2$\pm$147.9 kcal/day, while the predicted value by Harris-Benedict, WHO/FAO/UNU and Cunningham were 1373.3$\pm$45.4 kcal/day, 1290.0$\pm$61.7 kcal/day and 1187.6$\pm$49.2 kcal/day, respectively. The Cunningham equation was more closed to measured values than Harris-Benedict and WHO/FAO/UNU equation by the correlation coefficient. Comparing Pearson's correlation coefficients, fat-free mass (FFM), body surface area (BSA) and body weight were higher than others such as height, body mass index (BMI), fat and fat%. The FFM's correlation coefficient was the highest as 0.74. Thus, the conclusion of this study suggested that the main determinant of BEE was FFM, and we derived a prediction equation as follows: BEE=-569.86+48.27 (FFM).

• Communications for Statistical Applications and Methods
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• v.17 no.2
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• pp.293-308
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• 2010

In this paper, we examine the forecasting KOSPI 200 realized volatility by volatility measurements. The empirical investigation for KOSPI 200 daily returns is done during the period from 3 January 2003 to 29 June 2007. Since Korea Exchange(KRX) will launch VKOSPI futures contract in 2010, forecasting VKOSPI can be an important issue. So we analyze which volatility measurements forecast VKOSPI better. To test this hypothesis, we use 5-minute interval returns to measure realized volatilities. Also, we propose a new methodology that reflects the synchronized bidding and simultaneously takes it account the difference between overnight volatility and intra-daily volatility. The t-test and F-test show that our new realized volatility is not only different from the realized volatility by a conventional method at less than 0.01% significance level, also more stable in summary statistics. We use the correlation analysis, regression analysis, cross validation test to investigate the forecast performance. The empirical result shows that the realized volatility we propose is better than other volatilities, including historical volatility, implied volatility, and convention realized volatility, for forecasting VKOSPI. Also, the regression analysis on the predictive abilities for realized volatility, which is measured by our new methodology and conventional one, shows that VKOSPI is an efficient estimator compared to historical volatility and CRR implied volatility.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.2
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• pp.151-159
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• 2014

PURPOSE: The purpose of this study was to evaluate whether light-emitting diodes (LED) irradiation could be effective in a noninvasive, therapeutic device for the treatment of osteoarthritis(OA). METHODS: Twenty-four male Sprague-Dawley rats were divided into four groups: Vehicle control (saline); monosodium iodoacetate-injection (MIA); LED irradiation after MIA injection (MIA-LED); indomethacin-treatment after MIA injection (MIA-IMT). OA was induced by intra-articular injection of 3 mg MIA through the patellar ligament of the right knee. Vehicle control rats were injected with an equivalent volume of saline. The LED was irradiated for 15 min/day for a week after 7 days of MIA treatment. To compare with the effect of LED irradiation, the indomethacin was administrated 20 mg/kg twice a week orally after 7 days of MIA treatment. Knee joints were removed and fixed overnight in 10% neutral buffered formalin and decalcified by EDTA for 2 week before being embedded in paraffin. The assessment of OA induction were monitored by knee movement and radiographic finding. Histologic analysis were performed following staining with hematoxylin and eosin, safranin O-fast green, or toluidine blue, picrosirius red, and histologic changes were scored according to a modified Mankin system. Apoptotic cell in tissue sections was detected using TUNEL method. RESULTS: Radiographic examination could not show the differences between the MIA-treated and the MIA-LED-treated rats. In the histologic analysis, however, LED irradiation prevented cartilage damage and subchondral bone destruction, and significantly reduced mononuclear inflammatory cell infiltration and pannus formation. LED irradiation also reduced apoptosis of cartilage cells, but it prevented apoptosis of infiltrated inflammatory cells in synovium. In addition, LED irradiation showed an increase of collagen production in the meniscus. CONCLUSION: These results suggest that the 840 nm LED irradiation would be a suitable non-thermal phototherapy for the treatment of OA, as a cartilage protection and anti-inflammatory modality.

• Food Science of Animal Resources
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• v.30 no.2
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• pp.179-184
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• 2010

Escherichia coli O157:H7 is a food-borne pathogen that causes bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). We compared three selective media and evaluated the performance of immunomagnetic separation (IMS) for the detection of low levels of E. coli O157:H7 in ground beef and radish sprouts with different levels of background flora. Bulk food samples (500 g for each trial) were artificially inoculated with nalidixic acid-resistant E. coli O157:H7 at the lowest dose that would generate 20 partial-positive samples of 25 g each. All samples were homogenized in mTSB (225 mL) and incubated overnight at $37^{\circ}C$. IMS was performed using the enriched mTSB samples (1 mL) along with conventional spreads plated onto three different selective media: Sorbitol MacConkey agar (SMAC), Sorbitol MacConkey agar with cefixime and tellulite (CT-SMAC), and Sorbitol MacConkey agar with nalidixic acid (NAL-SMAC) as the gold standard. Two suspicious colonies from each medium were selected and confirmed usinga serological test after transfer to tryptic soy broth with yeast extract (TSAYE). CT-SMAC was better than SMAC for detecting E. coli O157:H7 in all food types. Although there was no statistical difference in the number of positive samples when using IMS vs. non-IMS techniques, more positive samples were detected when IMS was used in both ground beef and radish sprouts. It appears that the improvement was more significant in radish sprouts, which had a higher level of background flora than ground beef. The results also suggest that the combination of CT-SMAC and IMS is sufficient to recover low levels of E. coli O157:H7 in high background flora food samples.

• Radiation Oncology Journal
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• v.19 no.2
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• pp.163-170
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• 2001

Purpose : The measurement of radiation survival using a clonogenic assay, the established standard, can be difficult and time consuming. In this study, We have used the MTT assay, based on the reduction of a tetrazolium salt to a purple formazan precipitate by living cells, as a substitution for clonogenic assay and have examined the optimal condition for performing this assay in determination of radiation sensitivity. Materials and Methods : Four human cancer cell lines - PCI-1, SNU-1066, NCI-H630 and RKO cells have been used. For each cell line, a clonogenic assay and a MTT assay using Premix WST-1 solution, which is one of the tetrazolium salts and does not require washing or solubilization of the precipitate were carried out after irradiation of 0, 2, 4, 6, 8, 10 Gy. For clonogenic assay, cells in $25\;cm^2$ flasks were irradiated after overnight incubation and the resultant colonies containing more than 50 cells were scored after culturing the cells for $10\~14$ days. For MTT assay, the relationship between absorbance and cell number, optimal seeding cell number, and optimal timing of assay was determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth or when the non-irradiated cells had undergone four or more doubling times. Results : There was minimal variation in the values gained from these two methods with the standard deviation generally less than $5\%$, and there were no statistically significant differences between two methods according to t-test in low radiation dose (below 6 Gy). The regression analyses showed high linear correlation with the $R^2$ value of $0.975\~0.992$ between data from the two different methods. The optimal cell numbers for MTT assay were found to be dependent on plating efficiency of used cell line. Less than 300 cells/well were appropriate for cells with high plating efficiency (more than $30\%$). For cells with low plating efficiency (less than $30\%$), 500 cells/well or more were appropriate for assay. The optimal time for MTT assay was after 6 doubling times for the results compatible with those of clonogenic assay, at least after 4 doubling times was required for valid results. In consideration of practical limits of assay (12 days, in this study) cells with doubling time more than 3 days were inappropriate for application. Conclusion : In conclusion, it is found that MTT assay can successfully replace clonogenic assay of tested cancer cell lines after irradiation only if MTT assay was undertaken with optimal assay conditions that included plating efficiency of each cell line and doubling time at least.

• Sleep Medicine and Psychophysiology
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• v.23 no.1
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• pp.16-24
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• 2016

Background and Objectives: Obstructive sleep apnea (OSA) is often undiagnosed but is an important risk factor affecting the health of an individual. The level of awareness of the illness among patients with OSA is low and is not correlated with severity of the illness. This study was conducted to compare awareness of OSA symptoms and illness between patients with OSA and simple snorers. Materials and Methods: Two hundred eighty-two patients who were suspected of having OSA participated in this study. All subjects underwent overnight polysomnography. Those with an apnea-hypopnea index (AHI) ${\geq}5$ were classified as the OSA group, while those with an AHI < 5 were classified as the simple snoring group. A sleep questionnaire, which included items on awareness of the illness, OSA, and sleep symptoms, was administered to all subjects and their bed-partners. Results: Simple snorers were much more aware of their symptoms such as snoring, irregular breathing, and apnea than were patients with OSA. Bed-partners of simple snorers were also more aware of the participants' sleep symptoms than were partners of patients with OSA. However, the duration of OSA symptoms was longer in the OSA group. In the correlation analysis, the level of awareness of OSA symptoms was negatively correlated with AHI, age, body mass index, and Epworth Sleepiness Scale score. Among the sleep questionnaire and polysomnography results, only Pittsburgh Sleep Quality Index was positively correlated with level of awareness of OSA symptoms. The minority of the respondents had heard about the treatment methods of continuous positive airway pressure and oral appliance and preferred them as treatment options. Conclusion: This study suggests that simple snorers are more aware of their symptoms than are patients with OSA. A higher severity of OSA, represented by a higher AHI, is correlated with lower awareness of one's OSA symptoms.

• Clinical and Experimental Pediatrics
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• v.51 no.1
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• pp.42-46
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• 2008

Purpose : Apolipoprotein E (Apo E) plays a major role in lipoprotein metabolism and lipid transport. Many investigators have described that Apo E polymorphisms is one of the most important genetic determinants for cardiovascular disease. The purpose of this study was to evaluate the association between Apo E polymorphisms and serum lipid profiles in obese adolescent. Methods : We measured the serum concentrations of glucose, apolipoprotein (Apo) A1, Apo B, total cholesterol (TC), triglyceride (TG), HDL and LDL-cholesterol after overnight fasting in obese adolescent. Apo E polymorphisms were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results : 86 obese adolescents participated in this study. The body mass index (BMI) of participants were excess of 95 percentile by age and sex. Male to female ratio was 1.7 and mean age of study group was $16.2{\pm}1.8\;years$. Mean BMI was $27.4{\pm}2.5kg/m^2$. The frequency of ${\varepsilon}2$, ${\varepsilon}3$ and ${\varepsilon}4$ allele were 8.1%, 87.2% and 4.7% respectively. Study populations were classified into the following three genotypes 1) Apo E2 group (n=13, 15.1%) carrying either the ${\varepsilon}2/{\varepsilon}2$ or ${\varepsilon}2/{\varepsilon}3$ 2) Apo E3 group (n=65, 75.6%) carrying the most frequent ${\varepsilon}3/{\varepsilon}3$ 3) Apo E4 group (n=8, 9.3%) carrying either the ${\varepsilon}3/{\varepsilon}4$ or ${\varepsilon}4/{\varepsilon}4$. No differences were found among Apo E genotypes concerning age, sex, weight, height and BMI. Apo B and LDL-cholesterol concentrations were significantly higher in the Apo E4 group (P<0.05). No association were found between Apo E genotypes and glucose, Apo A1, TC, TG and HDL. Conclusions : We confirmed that serum concentrations Apo B and LDL-cholesterol were influenced by Apo E genotypes. Apo E polymorphisms seems to influence some alteration of lipid metabolism associated with obesity in adolescent.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.9 no.2
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• pp.227-236
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• 1998

Objectives：Conduct disorder is one of the most frequent diagnosis in outpatient and inpatient mental health facilities for children and adolescents. This study investigated the clinical characteristics of children and adolescents with conduct disorder. Methods：The study employed a retrospective review of 45 inpatients diagnosed with conduct disorder by DSM-IV criteria at SNUH Child Psychiatric Unit from 1993, March to 1998, September. Results：The results were as follows：1) The sex ratio was 2：1, male dominant. Mean age on admission was $12.8{\pm}2.4$ years old(male：$12.2{\pm}2.3$, female：$14.1{\pm}2.1$). The mean age of male subjects was significantly lower than that of female subjects(p<.05). 2) We classified all subjects according to child- or adolescent-onset type by DSM-Ⅳ. Childhoodonset type was 42.2%, and adolescent-onset, 57.8%. The onset of male subjects were significantly earlier than that of female subjects(p<.05). 3) The most common complaint was 'serious violation of rules'(77.8%) by DSM-Ⅳ dimensions, while the most common single symtom was 'run away from home overnight at least twice while living in parental or parental surrogate home'(48.9%). 4) The comorbid psychopathology of the subjects were frequently described as follows, in order of frequency：substance use(42.2%), ADHD(35.6%), depression(20.0%), tic disorder(11.1%), bipolar disorder(4.4%). 5) On MMPI, both Pd and Ma subscales got the highest scores. The mean of total IQ by KEDIWISC was $100.0{\pm}15.1$. Female subjects' IQ was higher than that of male subjects. 6) Regarding the number of visits to the OPD after discharge, many subjects(33.3%) had visited OPD fewer than four times. Conclusions：In this study, the male to female ratio of adolescent type showed a decreasing trend. An interesting finding was the fact that socio-economic circumstances, as well as the level of education among patients, were higher than those of previous studies. The subjects' problem were also principally self contered and posed no threat to others.

• Sleep Medicine and Psychophysiology
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• v.15 no.2
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• pp.77-81
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• 2008

Introduction: REM sleep which shows characteristic muscle atonia and increased resistance of upper respiratory track is known to be vulnerable to sleep apnea. Previous studies reported that REM sleep-dependent (or related) obstructive sleep apnea syndrome (REM-dependent OSA) could be one of sleep disordered breathing. The present study aimed to investigate clinical findings and polysomnographic variables of REM-dependent OSA. Methods: Fifty-six patients diagnosed with mild to moderate obstructive sleep apnea by overnight polysomnography (5$53.7{\pm}16.7$ years, 42 males). REM-dependent OSA was defined as AHI-REM/AHI-NREM ratio>2. We compared clinical and polysomnographic findings between REM-dependent OSA and No REM-dependent OSA patients. Results: Among 56 patients, 37.5% (n=21, average age of $52.3{\pm}19.7$ years, 14 males) met the REM-dependent OSA criteria. There were no significant differences in age, sex and body mass index between two groups. After controlling for age, sex, body mass index and periodic leg movements index, REM-dependent OSA patients showed significantly lower AHI, lower number of oxygen desaturation events and higher stage 2 sleep proportion compared to No REM-dependent OSA patients (p=0.010, p=0.006, p=0.031, respectively). After controlling for age, sex, body mass index and periodic legs movements index, AHI-REM was positively correlated with the number of oxygen desaturation events in REM-dependent OSA group (p=0.002). Conclusion: Current results suggested that 37.5% of patients with mild to moderate severity of obstructive sleep apnea could be classified into REM-dependent OSA. REM-dependent OSA was more common in mild severity of OSA, equally prevalent in both sexes and accompanied with sleep architecture changes, i.e. increased proportion of stage 2. In addition, apneic events during REM sleep in REM-dependent OSA were related to oxygen desaturation.