Publications by authors named "Yonghoon Park"

The southern area of South Korea consists of three parts; Busan, Ulsan and Gyeongsangnam-do. Busan Institute of National Forensic Service (NFS) performed about 50,000 cases throughout the southern area in 2014, occupying over 15% of total cases covered by NFS. In this study, patterns of drugs and poisons in the southern area of South Korea were investigated.

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One hundred and twenty six seized methamphetamine (MA) samples were analyzed using GC-MS. All the peaks that appeared in the chromatograms were investigated and 61 impurities including n-octacosane (internal standard) were identified. Among them, 37 impurities were already known or newly identified by comparing with commercial library entries and 18 impurities were detected for the first time.

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Dried Blood Spot (DBS) has been used a blood extraction method for inherited metabolic disorder screening since 1960s. With introduction of LC-MS/MS, not only DBS could be used to analysis drugs in small blood volume, but in various fields, such as toxicology, drug therapeutic monitoring, drug diagnostic screening, and illicit drugs. In toxicology field, many drugs (e.

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The aim of this study was to investigate the relationship between methamphetamine (MA) use history and segmental hair analysis (1 and 3cm sections) and whole hair analysis results in Korean MA users in rehabilitation programs. Hair samples were collected from 26 Korean MA users. Eleven of the 26 subjects used cannabis with MA and two used cocaine, opiates, and MDMA with MA.

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Nereistoxin(NTX) was originated from a marine annelid worm Lumbriconereis heteropoda and its analogue pesticides including cartap, bensultap, thiocyclam and thiobensultap have been commonly used in agriculture, because of their low toxicity and high insecticidal activity. However, NTX has been reported about its inhibitory neuro toxicity in human and animal body, by blocking nicotinic acetylcholine receptor and it cause significant neuromuscular toxicity, resulting in respiratory failure. We developed a new method to determine NTX in biological fluid.

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Background: Atypical hemolytic uremic syndrome (aHUS) is a rare disease with a genetic predisposition. Few studies have evaluated the disease in the Asian population. We studied a Korean pediatric cohort to delineate the clinical characteristics and genotypes.

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Background: Progressive retinal degeneration without retinal pigmentation has been repeatedly observed in Korean nephronophthisis (NPHP) type 1 patients with a total homozygous deletion of NPHP1.

Design: Retrospective case series.

Participants: Patients with clinical diagnosis of NPHP and genetic diagnosis of total deletion of NPHP1 (n = 5) were included in this study.

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Background: Dent disease, an X-linked recessive renal tubulopathy, is caused by mutations in either CLCN5 (Dent disease 1) or OCRL (Dent disease 2). OCRL mutations can also cause Lowe syndrome. In some cases it is difficult to differentiate Dent disease 1 and 2 on the basis of clinical features only without genetic tests.

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Hair analysis has been regarded as an alternative method to urine analysis in forensic and criminal cases. Cannabis (marijuana) is one of the most widely used drugs in the world and it has been controlled in South Korea since 1976. Identification of 11-nor-9-carboxy-tetrahydrocannabinol (THCCOOH) in hair can be an important proof of cannabis use because it can exclude the possibility of passive cannabis smoke exposure.

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The information about the sources of supply, trafficking routes, distribution patterns and conspiracy links can be obtained from methamphetamine profiling. The precursor and synthetic method for the clandestine manufacture can be estimated from the analysis of minor impurities contained in methamphetamine. Also, the similarity between samples can be evaluated using the peaks that appear in chromatograms.

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After gas chromatography-mass spectrometry (GC-MS) analysis, data processing, including retention time correction, spectral deconvolution, peak alignment, and normalization prior to statistical analysis, is an important step in metabolomics. Several commercial or free software packages have been introduced for data processing, but most of them are vendor dependent. To design a simple method for Agilent GC/MS data processing, we developed an in-house program, "CompExtractor", using Microsoft Visual Basic.

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A quality control material (QCM) is a necessity in hair drug analysis, but it is not always easy to have an authentic hair sample containing various target drugs and metabolites. In the present study, the feasibility of rat hair as a QCM was examined for its application in the determination of methamphetamine (MA) and amphetamine (AP) in human hair. MA was administered to lean Zucker rats, from which only pigmented hair was collected for the preparation of a QCM.

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The present study describes a gas chromatography/tandem mass spectrometry-negative ion chemical ionization assay (GC/MS/MS-NCI) for simultaneous analysis of Δ(9)-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-tetrahydrocannabinol (THCCOOH) in hair. Each hair sample, of approximately 20mg, was weighed and the sample was dissolved in 1ml of 1M sodium hydroxide (30min at 85°C) in the presence of THC-d(3) and THCCOOH-d(3). For the analysis of THC, hair samples were extracted with n-hexane:ethyl acetate (9:1) two times; acetic acid and sodium acetate buffer were added for the analysis of THCCOOH, and hair samples were re-extracted with n-hexane:ethyl acetate (9:1) two times.

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Impurities in 48 methamphetamine (MA) samples were analyzed by liquid-liquid extraction (LLE) and headspace solid-phase microextraction (HS-SPME) methods. MPS-2 autosampler was used to improve reproducibility of SPME method, and nonadecane (C(19)) diluted with potassium bromide (KBr) powder was used as an internal standard for standardizing retention time. Impurities identified by SPME method showed different patterns compared with LLE method.

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In this paper, the incorporation of methamphetamine (MA) into rat hair was studied. The main purpose of this study was to investigate whether MA can be detected or positive hair results can be obtained in hair of rats administered a single dose of MA. The relationship between dose and frequency of administration and the concentrations of MA and its metabolite, amphetamine (AP), in rat hair were evaluated and the MA and AP concentrations in white and pigmented hair were compared.

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In zebrafish embryos, bilateral symmetry is broken by asymmetric nodal flow generated in Kupffer's vesicle (KV), the transient cilia-rich organ, analogous to the mouse node. Asymmetric nodal flow induces the asymmetric expression of several genes, which are critical for the determination of correct LR body patterning. seson encoding three consecutive C2H2 zinc finger protein is predominantly expressed in the cilia-rich organs including KV.

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In the preparation of a reference material (RM) for quality assurance, both homogeneity and stability studies are integral parts. In the present study, both homogeneity and stability of a candidate RM for the determination of methamphetamine and amphetamine in hair were examined by an isotope dilution gas chromatography/mass spectrometry (GC/MS) method, which is not only one of the analytical methods validated in our previous study but also one of the primary methods for the preparation of a certified reference material (CRM). Additionally, homogeneity was monitored using a different method: micropulverized extraction followed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), which was fully validated in the previous study.

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Opium poppy products are often illegally used for both recreational and medicinal purposes. In order to demonstrate the ingestion of opium poppy substances, morphine, codeine and their metabolites have been identified. However, morphine and codeine also originate from the ingestion of therapeutic drugs.

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Beta-amyloid (Abeta)-induced neurotoxicity is considered to be mediated through the formation of reactive oxygen species (ROS). In this study, the protective effects of Poria cocos water extract (PCW) against Abeta1-42-induced cell death were investigated using rat pheochromocytoma (PC12) cells. Exposure of PC12 cells to the Abeta1-42 (20 microM) for 48h resulted in neuronal cell death, whereas pretreatment with PCW at the concentration range of 5-125 microg/ml reduced Abeta1-42-induced cell death.

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In order to aid the interpretation of hair results from methamphetamine (MA) abusers the MA and amphetamine (AP) concentrations in 2070 hair samples were statistically evaluated. The MA and AP concentrations in hair were put into three groups arbitrarily representing low, medium and high ranges and the metabolite-to-parent drug ratios of each group were examined. The concentration ranges proposed here were also applied to the interpretation of five authentic cases.

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Nail-patella syndrome (NPS) is an autosomal dominant disease that typically involves the nails, knees, elbows and the presence of iliac horns. In addition, some patients develop glomerulopathy or adult-onset glaucoma. NPS is caused by loss-of-function mutations in the LMX1B gene.

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The measurement uncertainties (MUs) were estimated for the determination of methamphetamine (MA) and its main metabolite, amphetamine (AP) at the low concentrations (around the cut-off value of MA) in human hair according to the recommendations of the EURACHEM/CITAC Guide and "Guide to the expression of uncertainty in measurement (GUM)". MA and AP were extracted by agitating hair with 1% HCl in methanol, followed by derivatization and quantification using GC-MS. The major components contributing to their uncertainties were the amount of MA or AP in the test sample, the weight of the test sample and the method precision, based on the equation to calculate the mesurand from intermediate values.

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Quality assurance is one of the major issues in forensic analytical laboratories, where the need for a reference material (RM) has rapidly increased. RMs are very useful for method development and validation, internal quality control or proficiency tests. In the present study, we prepared a RM using drug-free hair for the determination of methamphetamine (MA) and its main metabolite, amphetamine (AP) according to the recommendations of ISO Guide 35.

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In the present study, we developed a reference material (RM) using authentic hair samples for the determination of methamphetamine (MA) and its main metabolite, amphetamine (AP) in human hair. MA abusers' hair samples were collected, homogenized and finally bottled. The concentration of each bottle was determined using two extraction methods, agitation with 1% HCl in methanol at 38 degrees C and ultrasonication with methanol/5M HCl (20:1), followed by gas chromatography/mass spectrometry (GC-MS) after derivatization with trifluoroacetic anhydride (TFAA).

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The object of this study was to validate the Immunalysis Methamphetamine Microplate ELISA for detecting methamphetamine in hair. Twenty-nine scalp hair samples were obtained as routine cases submitted to the National Institute of Scientific Investigation in Seoul by the police. The hair samples were washed with 0.

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