• Mass Spectrometry Letters
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• v.12 no.3
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• pp.81-84
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• 2021

Collagen, which accounts for one-third of human protein, is reduced due to human aging, and much attention is focused on making collagen into food to prevent such aging. Gel permeation chromatography with Reflective Index (RI) detection (GPC/RI) was chosen as the most suitable instrument to confirm molecular weight distribution, and we explored the use of this technique for analysis of collagen peptide molecular sizes and distributions. Data reliability was verified by matrix-assisted laser desorption/ionization coupled to time-of-flight (MALDI-TOF) mass spectrometric analysis. The data were considered meaningful for comparative analysis of molecular weight distribution patterns.

• YAKHAK HOEJI
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• v.36 no.3
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• pp.230-240
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• 1992

The metabolic profile of doxylamine, N,N-dimethyl-2-[1-phenyl-1-(2-pyridinyl)ethoxy] ethanamine, was determined in the human urine. The free fractions of extracts were obtained without hydrolysis, and the conjugated fractions of extracts were obtained with enzyme hydrolysis using ${\beta}-glucuronidase/arylsulfatase$ from Helix pomatia. The mixture of acetic anhydride/pyridine (10 : 1, v : v) was used to derivatize the urinary extracts and then analyzed by gas chromatography and mass selective detector. N-desmethyldoxylamine, doxylamine carboxylic acid, desaminohydroxydoxylamine, N, N-didesmethyldoxylamine, N-acetyl conjugates of N-desmethyl and N, N-didesmethyldoxylamine, quarternary ammonium N-glucuronide of doxylamine, N-desmethyldoxylamine N-glucuronide and unchanged doxylamine were detected in the human urine obtained after oral treatment with doxylamine succinate. $N-methyl-{\alpha}-hydroxy-2-[1-phenyl-1-(2-pyridinyl)$ ethoxy] ethanamine, which can be a key intermediate of this metabolism, was tentatively identified by the interpretation of its mass spectrum. In this study, we proposed the metabolic pathway of doxylamine in the human on the basis of our data of the identified metabolites of doxylamine.

• Mass Spectrometry Letters
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• v.11 no.4
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• pp.118-124
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• 2020

An analytical method was developed for hypoxia-inducible factor (HIF) stabilizers based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) sample preparation and liquid chromatography-high resolution mass spectrometry analysis. HIF stabilizers potentially enhance the performance of athletes, and hence, they have been prohibited. However, the analysis of urinary HIF stabilizers is not easy owing to their unique structure and characteristics. Hence, we developed the QuEChERS preparation technique for a complementary method and optimized the pH, volume of extraction solvent, and number of extractions. We found that double extraction with 1% of formic acid in acetonitrile provided the highest recovery of HIF stabilizers. Moreover, the composition of the mobile phase was also optimized for better separation of molidustat and IOX4. The developed method was validated in terms of its precision, detection limit, matrix effect, and recovery for ISO accreditation. To the best of our knowledge, this is the first demonstration of the application of the QuEChERS method, which is suitable as a complementary analytical method, in antidoping.

• Mass Spectrometry Letters
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• v.9 no.1
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• pp.30-36
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• 2018

A quantitation method for free amino acids in human serum was developed using a stepwise-dilution method and a bimodal cation exchange (CEX)/hydrophilic interaction liquid chromatography (HILIC)-tandem mass spectrometry system equipped with an electrospray ionization source (ESI/MS/MS). This method, which was validated using quality control samples, was optimized for enhanced selectivity and sensitivity. Dithiothreitol (DTT) was used as a reducing agent to prevent the oxidation of a serum sample ($50{\mu}L$), which was then subjected to stepwise dilution using 3, 30, and 90 volumes of acetonitrile containing 0.1% formic acid. Chromatographic separation was performed on an Imtakt Intrada Amino Acid column ($50mm{\times}3mm$, $3{\mu}m$) in mixed mode packed with CEX and HILIC ligands embedded in the stationary phase. Underivatized free amino acids were eluted and separated within 10 min. As a result of the validation, the precision and accuracy for the inter- and intraday assays were determined as 2.11-11.51% and 92.82-109.40%, respectively. The lowest limit of quantification (LLOQ) was $0.5-4.0{\mu}g/mL$ and the matrix effect was 80.22-115.93%. The proposed method was successfully applied to the quantitative analysis of free amino acids in human serum.

• Journal of Veterinary Clinics
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• v.32 no.1
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• pp.127-129
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• 2015

A 3-month-old, female Persian cat was presented with sclera mass. The mass was detected after cat's squeals during the playing with a dog before 2 days. On ophthalmic examination, a $2{\times}5mm$ dark purple colored raised mass was observed 1 mm behind the limbus in the right eye. Anterior chamber was filled with blood and epithelial defect was detected at 2 o'clock in the right central cornea. After general anesthesia, resection of the protruded iris was performed with iris scissors and bipolar cautery. Ruptured sclera and conjunctiva were closed with simple interrupted and simple continuous suture, respectively. Also, irrigation and aspiration (I/A) of the anterior chamber was performed to remove blood clot with bimanual I/A handpiece in the right eye. Four months after the surgery, the right eye was recovered completely and menace response was positive in spite of the retinal lesions.

• Mass Spectrometry Letters
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• v.3 no.3
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• pp.74-77
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• 2012

Organic acid (OA) profiling analysis was performed in culture media from Lactobacillus pentosus K34 (L. pentosus K34) and Pediococcus lolli PL24 (P. lolli PL24) by gas chromatography-mass spectrometry (GC-MS) following methoxime/tert-butyldimethylsilyl derivatives. 12 OAs were positively identified in culture media. Most of OA levels from L. pentosus K34 of hetero lactic fermentation were found to be higher when compared with those from P. lolli PL24 of homo lactic fermentation, which may explain different OA metabolism in each strain. In addition, the distorted dodecagonal star patterns were readily distinguishable, and the characteristics of each strain were well represented. The present study demonstrates that the OA metabolic profiling method by GC-MS combined with star pattern recognition is useful for the monitoring study of characteristic OA metabolism in various microorganisms.

• Analytical Science and Technology
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• v.36 no.2
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• pp.89-98
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• 2023

Analytical methods for detecting atranol, chloroatranol, evernic acid, (+)-usnic acid, and atranorin in sanitary napkins and mouthwashes were developed using ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). UHPLC-MS/MS conditions were optimized for rapid, sensitive, and simultaneous analysis of the five allergenic compounds. The methods were validated by assessing their specificity, matrix effects, limit of detection (LOD), limit of quantification (LOQ), linearity, accuracy, and precision. Good linearity was achieved with a determination coefficient of ≥0.99. The LOD and LOQ were 2.1-9.8 and 6.4-29.6 ng/g for sanitary napkins and 0.29-0.48 and 0.87-1.45 ng/mL for mouthwashes, respectively. The accuracy and precision were within an acceptable range according to the criteria reported in the European SANTE/11813/2017 guidelines (70-120 % recovery, <20 % relative standard deviation). Therefore, these methods can be used to analyze atranol, chloroatranol, evernic acid, (+)-usnic acid, and atranorin in sanitary napkins and mouthwashes.

• Tuberculosis and Respiratory Diseases
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• v.76 no.1
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• pp.38-41
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• 2014

Immunoglobulin G4 (IgG4)-related disease is a newly recognized condition characterized by fibroinflammatory lesions with dense lymphoplasmacytic infiltration, storiform-type fibrosis and obliterative phlebitis. The pathogenesis is not fully understood but multiple immune-mediated mechanisms are believed to contribute. This rare disease can involve various organs and pleural involvement is even rarer. We report a case of IgG4-related disease involving pleura. A 66-year-old man presented with cough and sputum production for a week. Chest radiography revealed consolidation and a pleural mass at right hemithorax. Treatment with antibiotics resolved the consolidation and respiratory symptoms disappeared, but the pleural mass was unchanged. Video-assisted thoracoscopic surgery was performed. Histopathology revealed dense lymphoplasmacytic infiltration and storiform fibrosis with numerous IgG4-bearing plasma cells. The serum IgG4 level was also elevated. Further examination ruled out the involvement of any other organ. The patient was discharged without further treatment and there is no evidence of recurrence to date.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.36.2-36.2
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• 2014

We present results of the analysis of FLS 1718+59, a galaxy-galaxy gravitational lens system in the Spitzer First Look Survey (FLS) Field. A background galaxy (z = 0.245) is severely distorted by an elliptical galaxy (z = 0.08), by gravitational lensing. We analyze this system by several methods, including Ellipse and Galfit fitting, gravitational lens modeling (gravlens), and SED fitting. Properties of the lens galaxy can be obtained: from Galfit we measure the effective radius and the average surface brightness inside it, and from gravlens we estimate the total mass inside the Einstein radius (lensing mass). We use these parameters to check that the lens galaxy is located on the Fundamental Plane. Also, we conduct SED fitting for the lens galaxy and estimate the stellar mass, and compare this with the lensing mass of the lens galaxy to check the M-L relation.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.9
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• pp.22-29
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• 1995

An experimental method to identify the rigid properties (mass, moment of inertia, center of mass) of mounted structures is presented. A direct system identification method is developed and applied to identify the mass, damping and stiffness martix directly from the translational response of vibration testing. Conventional method is sensitive to noise since it needs artificial rotational response of temporary center of mass which is made by the linear transformation of translational response. A presented method needs only the translational response, and it is robuster to noise than conventional method. Several experimental and numerical implementations show the presented method is effective.