• Analytical Science and Technology
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• v.19 no.5
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• pp.441-448
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• 2006

11-nor-9-carboxy-${\Delta}^9$-tetrahydrocannabinol (THCCOOH) is the major metabolite of tetrahydrocannabinol (THC) which is the primary psychoactive component of marijuana. It is also the target analyte for the discrimination marijuana use. A method using solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) was developed for the determination of THCCOOH in human urine. Urine samples (3 mL) were extracted by SPE column with a cation exchange cartridge after basic hydrolysis. The eluents were then evaporated, derivatized, and injected into the GC/MS. The limits of detection (LOD) and quantitation (LOQ) were 0.4 and 1.2 ng/mL, respectively. The response was linear with a correlation coefficient of 0.999 within the concentration range of 1.2 (LLE 1.3)~50.0 ng/mL. The precision and accuracy were stable within 1.20% and the recovery was 83.6~90.7%. The recovery of SPE method was lower than that of liquid-liquid extraction (LLE), but there were no apparent differences in LOD, LOQ, precision and accuracy between the two methods. While SPE method is used as a very effective and rapid procedure for sample pretreatment, and clean extracts, LLE method was not suitable for the extraction procedure of THCCOOH in urine. The applicability of the method was proven by analyzing a urine samples from a marijuana abusers.

• Korean Journal of Radiology
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• v.20 no.5
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• pp.854-861
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• 2019

Objective: To evaluate quantitative magnetic resonance imaging (MRI) parameters for differentiation of cysts from and solid masses in the anterior mediastinum. Materials and Methods: The development dataset included 18 patients from two institutions with pathologically-proven cysts (n = 6) and solid masses (n = 12) in the anterior mediastinum. We measured the maximum diameter, normalized T1 and T2 signal intensity (nT1 and nT2), normalized apparent diffusion coefficient (nADC), and relative enhancement ratio (RER) of each lesion. RERs were obtained by non-rigid registration and subtraction of precontrast and postcontrast T1-weighted images. Differentiation criteria between cysts and solid masses were identified based on receiver operating characteristics analysis. For validation, two separate datasets were utilized: 15 patients with 8 cysts and 7 solid masses from another institution (validation dataset 1); and 11 patients with clinically diagnosed cysts stable for more than two years (validation dataset 2). Sensitivity and specificity were calculated from the validation datasets. Results: nT2, nADC, and RER significantly differed between cysts and solid masses (p = 0.032, 0.013, and < 0.001, respectively). The following criteria differentiated cysts from solid masses: RER < 26.1%; nADC > 0.63; nT2 > 0.39. In validation dataset 1, the sensitivity of the RER, nADC, and nT2 criteria was 87.5%, 100%, and 75.0%, and the specificity was 100%, 40.0%, and 57.4%, respectively. In validation dataset 2, the sensitivity of the RER, nADC, and nT2 criteria was 90.9%, 90.9%, and 72.7%, respectively. Conclusion: Quantitative MRI criteria using nT2, nADC, and particularly RER can assist differentiation of cysts from solid masses in the anterior mediastinum.

• Investigative Magnetic Resonance Imaging
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• v.17 no.2
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• pp.101-109
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• 2013

Objective: To investigate roles of dynamic contrast enhanced magnetic resonance (DCE MR) and diffusion-weighted (DW) imaging in preoperative prediction of underestimation of ductal carcinoma in situ (DCIS) ${\geq}2cm$ on US guided core needle biopsy. Materials and Methods: Twenty two patients with DCIS on US-guided 14 gauge core needle biopsy were included. Patients were divided into a group with and without DCIS underestimation based on histopathology. MR images including DCE and DW imaging were obtained with a 3.0-T MR. The lesion type (mass or non-mass), enhancement pattern, peak enhancement, and apparent diffusion coefficient (ADC) values of proven malignant masses were generated using software of CADstream and compared between two groups using Fisher's exact test and Mann Whitney test. Results: Eight patients were in the group with underestimation and 14 patients were in the group without underestimation. The lesion type and enhancement pattern were not different between two groups (P values = 1.000 and 0.613, respectively). The median peak enhancement of lesions with underestimation was 159.5%, higher than 133.5% of those without underestimation, but not significant (P value = 0.413). The median ADC value of lesions with underestimation was $1.26{\times}10^{-3}mm^2/sec$, substantially lower than $1.35{\times}10^{-3}mm^2/sec$ of those without underestimation (P value = 0.094). Conclusion: ADC values had the potential to preoperatively predict DCIS underestimation on US-guided core needle biopsy, although a large prospective series study should be conducted to confirm these results.

• Childhood Kidney Diseases
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• v.4 no.1
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• pp.63-68
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• 2000

Purpose: MCDK is regarded as a common cause of abdominal masses in children. And the presentation of the MCDK is usually a unilateral flank mass in the a newborn. Bialteral disease results in either fetal demise or necessity fer renal replacement therapy at birth. This study is designed to assess the clinical features and natural history of the unilateral multicystic dysplastic kidney. Patients and Methods: From January 1987 to January 2000 data were obtained retrospectively on 57 patients (28 boys and 29 girls, age ranged 1day-11years) who had a diagnosis of multicystic dysplastic kidney. The diagnosis of multicystic dysplastic kidney was confirmed by a combination of ultrasonography and radionuclide scan. Voiding cystourethrogram study in 31 patients were done to determine the condition of the contalateral kidney. Restllts: $84\%$ of the patients were diagnosed before birth by antenatal ultrasonography Clinical manifestations of children with postnatal diagnoses were palpable abdominal mass($3.5\%$), abdominal distension($17\%$), and incidental($10.5\%$). The abnormalities in contralateral kidney were hydronephrosis($21\%$), compensatory hypertrophy($12\%$), simple cyst($2\%$), bifid pelvis($2\%$). Surgical management was performed in 20 patients($35\%$) due to recurrent infection, for diagnostic purpose to differentiate from malignancy and abdominal distention. Follow-up in the remaining 37 patients continued (mean 18 months) and results of sonogram findings were involution change in 23 patients($40\%$) and no interval changes in 13 patient($23\%$). Conclusions : The apparent tendency to regression of the dysplastic kidney and no difference in the number of complications justify a conservative management rather than operative intervention except in associated severe complications such as urinary tract infection or rupture of cysts.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.4
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• pp.503-526
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• 1996

A synoptic survery of chemical characteristics in the last Sea of Korea was carried out at the 11 stations near Ullungdo in November, 1994 on board R/V Tam-Yang. On the basis of the vortical distribution patterns of temperature, salinity and dissolved oxygen, water masses in the study area are divided into five groups; 1) Tsushima Surface Water (TSW), 2) Tsushima Middle Water (TMW), 3) East Sea Intermediate Water (ESIW), 4) last Sea Proper Water (ESPW), 5) Mixed Water (MW). In the vertical profiles of nutrients, the concentrations were very low in the surface layer and increased rapidly near the thermocline. There was a slight decrease in the ESIW and the concentrations were constant with the depth below 300m except dissolved silicate which still increased with depth. Relatively high value of Si/P ratio (25.2) in ESPW, whick is the oldest water mass, suggests that Si is regenerating more slowly compared to other nutrients. The relatively high value of N/P ratio (18.6) in the surface layer might be related to high vertical eddy diffusivity $(K_z)$ of $1.19\;cm^{2}/sec$ and high nitrate upward flux of $103.7\;{\mu}g-at/m^{2}/hr$, compared to the values reported in other areas. Apparent Oxygen Utilization (AOU) was very low in the surface layer and increased in the TMW, but there was a slight decrease in the ESIW. The highest value of AOU occurred in the ESPW. The slpoe of P/AOU was 0.50. The study on the relationship between water masses and nutrient distribution patterns is important in understanding the regeneration processes of nutrients in the polar region of the last Sea.

• Economic and Environmental Geology
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• v.19 no.1
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• pp.67-83
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• 1986

Oriented hand samples were collected from Gobangsan Formation and Nogam Formation in the north of Danyang and south of Yeongchun, from Bansong Group in and around Danyang, from Nampo Group in Chungnam Coalfield, from Gyeongsang Supergroup distributed from Waegwan through Daegu to Gyeongsan and from Daegu to Goryong, and from volcanic flows in Jeongog area and Jeju Island to study the paleomagnetism of southern Korea since Permian. Stepwise alternating field and thermal demagnetization experiments were carried out to determine optimum fields and temperatures. Observed mean paleomagnetic directions are as follows: $D=331.5^{\circ}$, $I=25.1^{\circ}$, $a95=12.8^{\circ}$ for Permian, $D=325.6^{\circ}$, $I=46.1^{\circ}$, $a95=11.8^{\circ}$ for Triassic, $D=313.4^{\circ}$, $I=43.1^{\circ}$, $a95=16.0^{\circ}$ for early Jurassic, $D=41.3^{\circ}$, $I=64.6^{\circ}$, $a95=4.5^{\circ}$ for early Cretaceous, $D=28.3^{\circ}$, $I=58.1^{\circ}$, $a95=2.3^{\circ}$ for late Cretaceous, $D=2.0^{\circ}$, $I=55.8^{\circ}$, $a95=6.6^{\circ}$for Quaternary. To describe the tectonic translocation of southern Korean block, northern Eurasian continental block was used as a reference frame. For each age since Permian the expected northern Eurasian field directions in terms of paleolatitude and declination were calculated. The paleolatitudes of Permian ($13.2^{\circ}N$) and early Jurassic ($25.1^{\circ}N$) obtained from the study area are quite different from those of Permian ($66.0^{\circ}N$) and early Jurassic ($68.1^{\circ}N$) which are expected for northern Eurasia. The declinations of Permian ($331.5^{\circ}$) and early Jurassic ($313.4^{\circ}$) are also quite different from those of the Permian ($56.6^{\circ}$) and the early Jurassic ($47.5^{\circ}$) expected for northern Eurasia. The Cretaceous paleolatitude is similar to the expected within error limit, but the declination for the same period is significantly different from that of the expected for the northern Eurasia. From the above evidences it is suggested that the south Korean land mass had moved from low latitude in Permian to north and sutured to northern continental block since early Jurassic. The relative rotations of early Cretaceous($27.4^{\circ}$) and late Cretaceous($10.8^{\circ}$) to northern Eurasian continent reveal that the Korean land mass might be rotated clockwise in two different times, probably in late Early Cretaceous and in Tertiary.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.450-461
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• 2006

In this study, sorption kinetics of lead (Pb) and cadmium (Cd) onto coastal sediments were investigated at pH 5.5 using laboratory batch adsorbers. Four different models: one-site mass transfer model (OSMTM), pseudo-first-order kinetic model (PFOKM) ,pseudo-second-order kinetic model (PSOKM) and two compartment first-order kinetic model (TCFOKM) were used to analyze the sorption kinetics. As expected from the number of model parameters involved, the three-parameter TCFOKM was better than the two-parameter OSMTM, PFOKM and PSOKM in describing sorption kinetics of Pb and Cd onto sediments. Most sorption of Pb and Cd was rapidly completed within the first three hours, followed by slow sorption in the subsequent period of sorption. All models predicted that the sorbed amount at the apparent sorption ($q_{e,s}$) equilibria increased as the CEC and surface area of the sediments increased, regardless of initial spiking concentration ($C_0$) and heavy metal and the sediment type. The sorption rate constant ($k_s,\;hr^{-1}$) in OSMTM also increased as the CEC and BET surface area increased. The rate constant of pseudo-first-order sorption ($k_{p1,s},\;hr^{-1}$) in PFOKM were not correlated with sediment characteristics. The results of PSOKM analysis showed that the rate constant of pseudo-second-order sorption ($k_{p2,s},\;g\;mmol^{-1}\;hr^{-1}$) and the initial sorption rate ($v_{o,s},\;mg\;g^{-1}\;hr^{-1}$) were not correlated with sediment characteristics. The fast sorption fraction ($f_{1,s}$) in TCFOKM increased as CEC and BET surface increased regardless of initial aqueous phase concentrations. The sorption rate constant of fast fraction ($k_{1,s}=10^{0.1}-10^{1.0}\;hr^{-1}$) was much greater than that of slow sorption fraction ($k_{2,s}=10^{-2}-10^{-4}\;hr^{-1}$) respectively.

• Journal of Korean Neurosurgical Society
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• v.30 no.10
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• pp.1210-1219
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• 2001

Introduction : The purpose of this study was to analyze the safety, pullout strength and radiographic characteristics of unicortical and bicortical screws of cervical facet within cadaveric specimens and evaluate the influence of level of training on the positioning of these screws. Methods : Twenty-one cadavers, mean 78.9 years of age, underwent bilateral placement of 3.5mm AO lateral mass screw from C3-C6(n=168) using a slight variation of the Magerl technique. Intraoperative imaging was not used. The right side(unicortical) utilized only 14mm screws(effective length of 11mm) while on the left side to determine the length of the screw after the ventral cortex had been drilled. Three spine surgeons(attending, fellow, chief resident) with varying levels of spine training performed the procedure on seven cadavers each. All spines were harvested and lateral radiographs were taken. Individual cervical vertebrae were carefully dissected and then axial radiographs were taken. The screws were evaluated clinically and radiographically for their safety. Screws were graded clinically for their safety with respect to the spinal cord, facet joint, nerve root and vertebral artery. The grades consisted of the following categories : "satisfactory", "at risk" and "direct injury". Each screw was also graded according to its zone placement. Screw position was quantified by measuring a sagittal angle from the lateral radiograph and an axial angle from the axial radiograph. Pull-out force was determined for all screws using a material testing machine. Results : Dissection revealed that fifteen screws on the left side actually had only unicortical and not bicortical purchase as intended. The majority of screws(92.8%) were satisfactory in terms of safety. There were no injuries to the spinal cord. On the right side(unicortical), 98.9% of the screws were "satisfactory" and on the left side(bicortical) 68.1% were "satisfactory". There was a 5.8% incidence of direct arterial injury and a 17.4% incidence of direct nerve root injury with the bicortical screws. There were no "direct injuries" with the unicortical screws for the nerve root or vertebral artery. The unicortical screws had a 21.4% incidence of direct injury of the facet joint, while the bicortical screws had a 21.7% incidence. The majority of "direct injury" of bicortical screws were placed by the surgeon with the least experience. The performance of the resident surgeon was significantly different from the attending or fellow(p<0.05) in terms of safety of the nerve root and vertebral artery. The attending's performance was significantly better than the resident or fellow(p<0.05) in terms of safety of the facet joint. There was no relationship between the safety of a screw and its zone placement. The axial deviation angle measured $23.5{\pm}6.6$ degrees and $19.8{\pm}7.9$ degrees for the unicortical and bicortical screws, respectively. The resident surgeon had a significantly lower angle than the attending or fellow(p<0.05). The sagittal angle measured $66.3{\pm}7.0$ degrees and $62.3{\pm}7.9$ degrees for the unicortical and bicortical screws, respectively. The attending had a significantly lower sagittal angle than the fellow or resident(p<0.05). Thirty-three screws that entered the facet joint were tested for pull-out strength but excluded from the data because they were not lateral mass screws per-se and had deviated substantially from the intended final trajectory. The mean pull-out force for all screws was $542.9{\pm}296.6N$. There was no statistically significant difference between the pull-out force for unicortical($519.9{\pm}286.9N$) and bicortical($565.2{\pm}306N$) screws. There was no significant difference in pull-out strengths with respect to zone placement. Conclusion : It is our belief that the risk associated with bicortical purchase mandates formal spine training if it is to be done safely and accurately. Unicortical screws are safer regardless of level of training. It is apparent that 14mm lateral mass screws placed in a supero-lateral trajectory in the adult cervical spine provide an equivalent strength with a much lower risk of injury than the longer bicortical screws placed in a similar orientation.

• Radiation Oncology Journal
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• v.17 no.2
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• pp.113-119
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• 1999

Purpose : To evaluate possible acute toxicity and early response of concurrent radiation therapy and low dose daily cisplatin as a radiosensitizer in patients with locally advanced uterine cervical carcinomas. Materials and Method : From December 1996 to January 1999, 38 previously untreated Patients with locally advanced squamous cell carcinoma of the uterine cervix (from stage IIB to stage IIIB) were treated at Inha University Hospital. All patients underwent standard pretreatment staging Procedures after the initial evaluation by gynecologists and radiation oncologists. Sixteen Patients with huge cervical mass (>4 cm) were submitted to the group treated with concurrent radiation therapy and low dose daily cisplatin while the remainder was treated with radiation therapy alone. Radiation therapy consisted of 4500 cGy external beam irradiation to whole pelvis (midline block after 3000 cGy), 900$\~$1000 cGy boost to involved parametrium, and high dose-rate intracavitary brachytherapy (a total dose of 3000$\~$3500 cGy/500 cGy per fraction to point A, twice per week). In the group treated with low dose cisplatin concurrently, 10 mg of daily intravenous cisplatin was given from the 1st day of radiation therapy to the 20th day of radiation therapy. Acute toxicity was measured according to expanded common toxicity criteria of the NCI (C) Clinical Trials. Early response data were analyzed at minimum 4 weeks' follow-up after completion of the treatment protocol. Results: Hematolgic toxici쇼 was more prominent in patients treated with radiation therapy and cisplatin. Six of 16 patients (37.5$\~$) treated with radiation therapy and cisplatin and one of 22 patients (4.5$\~$) treated with radiation therapy alone experienced grade 3 leukopenia. In Fisher's exact test, there was statistically significant difference between two groups regarding leukopenia (P=0.030). There was no apparent difference in the frequency of gastrointestinal and genitourinary toxicity between two groups (P=0.066). Three of 16 patients (18.7$\~$) treated with radiation therapy and cisplatin and two of 22 patients (9.1$\~$) treated with radiation therapy alone experienced more than 5 kg weight loss during the treatment. There was no statistically significant difference on weight loss between two groups (P=0.63). Two patients on each group were not evaluable for the early response because of incomplete treatment. The complete response rate at four weeks' follow-up was 80$\~$(16/20) for the radiation therapy alone group and 78$\~$ (11/14) for the radiation therapy and cisplatin group. There was no statistically significant difference in early response between two treatment groups (P=0.126). Conclusion : This study led to the conclusion that the hematologic toxicity from the treatment with concurrent radiation therapy and low dose daily cisplatin seems to be more prominent than that from the treatment of radiation therapy alone. There was no grade 4 hematologic toxicity or mortality in both groups. The hematologic toxicity in both treatment groups seems to be well managable modically. Since the risk factors were not balanced between two treatment groups, the direct comparison of early response of both groups was not possible. However, preliminary results regarding early response for patients with bulky cervical tumor mass treated with radiation therapy and low dose daily cisplatin was encouraging. Longer follow-up is necessary to evaluate the survival data. A phase III study is needed to evaluate the efficacy of concurrent daily low dose cisplatin with radiation therapy in bulky cervical cancer.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.7 no.2
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• pp.228-238
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• 2004

Purpose: Obesity is rapidly increasing in Korean children. Obesity is a risk factor for cardiovascular morbidity and is frequently associated with hypertension, diabetes mellitus and coronary artery disease. This study was designed to evaluate risk factors of the metabolic syndrome in obese children. Methods: From February 2000 to June 2004, eighty eight obese (body mass index ${\geq}95th$ percentile) children aged 4 to 15 years were included. We measured serum lipid levels (total cholesterol, triglyceride, HDL cholesterol, LDL cholesterol), fasting sugar levels and insulin levels. Insulin resistance was determined by homeostasis model assessment, fasting insulin/glucose ratio and quantitative insulin sensitivity check index. Results: Clustering of risk factors for the metabolic syndrome in obese children demonstrated that 60.2% had more than one risk factors. Hypertension (14.8%), hypertriglyceridemia (14.8%), HDL-hypocholesterolemia (14.8%), LDL-hypercholesterolemia (12.5%) and hyperinsulinemia (12.5%) were observed. As BMI increased, there was statistically significant increase in systolic blood pressure, insulin and insulin resistance values. Insulin resistance was correlated to systolic blood pressure, serum lipid and insulin levels. The more risk factors for the metabolic syndrome obese children had, the higher was their insulin resistance. Conclusion: The increase in insulin resistance and clustering of risk factors for the metabolic syndrome are already apparent in obese children. Monitoring these risk factors for the metabolic syndrome should become a part of routine medical care for obese children.