Eun-Hyung Yoo

Glucose Biosensors: An Overview of Use in Clinical Practice

Blood glucose monitoring has been established as a valuable tool in the management of diabetes. Since maintaining normal blood glucose levels is recommended, a series of suitable glucose biosensors have been developed. During the last 50 years, glucose biosensor technology including point-of-care devices, continuous glucose monitoring systems and noninvasive glucose monitoring systems has been significantly improved. However, there continues to be several challenges related to the achievement of accurate and reliable glucose monitoring. Further technical improvements in glucose biosensors, standardization of the analytical goals for their performance, and continuously assessing and training lay users are required. This article reviews the brief history, basic principles, analytical performance, and the present status of glucose biosensors in the clinical practice.

Gallstone analysis using Fourier transform infrared spectroscopy (FT-IR).

Abstract Background: Gallstone analysis is important in determining the possible etiology of stone formation and the pathophysiology of cholelithiasis. Physical analysis using Fourier transform infrared spectroscopy (FT-IR), compared to chemical analysis, requires minimal sample volume, shows uniform sensitivity and specificity for all components and provides quantitative results with greater reproducibility. We studied the characteristics and distribution of gallstones using FT-IR in addition to the risk factors for gallstone formation in Korean patients. A better understanding of the mechanism underlying stone formation may help prevent gallstone development. Methods: Physical analysis of gallstones in 490 patients who underwent cholecystectomy was carried out using the FT-IR system 2000 (Perkin-Elmer Co.) and Spectrum™ software (Perkin-Elmer Co.). Visual inspection of the size, color, consistency and surface of the stones was compared with the physical characteristics. Clinical, demographic and laboratory findings were evaluated and compared with the gallstone components. Results: The FT-IR evaluation showed that most gallstones were composed of a single component (84.1%); cholesterol was the most commonly observed element among the major components (50%, 245/490). Morphological classification according to color, consistency and surface was different from the FT-IR composition analysis. There were significant differences in the components based on age, obesity, education level and the presence of diabetes mellitus. Conclusions: The results of this study show that physical analysis of gallstones with FT-IR provides important information on stone composition, distribution and risk factors. These study results will help improve our understanding of the pathophysiology of gallstone disease in the Korean population, where there is a high frequency of hepatobiliary disorders. Clin Chem Lab Med 2008;46:376–81.

The prevalence and risk factors for gallstone disease

Abstract Gallstone disease is one of the most prevalent gastrointestinal disorders. In addition, the costs associated with the diagnosis and treatment of gallstone disease have been rapidly increasing. The etiology and pathogenesis of gallstone disease remains incompletely understood. Gallstone formation may result from a complex interaction of genetic and environmental factors. This article reviews the prevalence and risk factors associated with gallstone disease. Understanding the pathogenesis of gallstone disease could lead to the development of better therapeutic and preventive strategies for dealing with this disease. Clin Chem Lab Med 2009;47:795–807.

A novel initiation codon mutation in the ribosomal protein S17 gene (RPS17) in a patient with Diamond‐Blackfan anemia

Diamond‐Blackfan anemia (DBA) is an inherited bone marrow failure syndrome characterized by pure red cell aplasia, various congenital anomalies, and cancer predisposition. We report a novel mutation in the RPS17 gene in a Korean patient with DBA. The mutation occurred in the translation initiation codon, changing Atg to Gtg (c.1A>G), thus disrupting the natural start of the RPS17 protein biosynthesis. This is the third case of DBA from a RPS17 mutation in the literature and is the second case of a RPS17 mutation in the translation initiation codon, following c.2T>G. Pediatr Blood Cancer 2010;54:629–631.

Clinical and genetic analysis of Korean patients with Marfan syndrome: possible ethnic differences in clinical manifestation

Yoo E‐H, Woo H, Ki C‐S, Lee HJ, Kim D‐K, Kang I‐S, Park P, Sung K, Lee CS, Chung T‐Y, Moon JR, Han H, Lee S‐T, Kim J‐W. Clinical and genetic analysis of Korean patients with Marfan syndrome: possible ethnic differences in clinical manifestation.

Frequent CD7 antigen loss in aggressive natural killer-cell leukemia: a useful diagnostic marker.

BACKGROUND Aggressive natural killer-cell leukemia (ANKL) is a rare neoplasm characterized by systemic proliferation of NK cells. However, the differential diagnosis of NK lymphoproliferative disorders is difficult because of the absence of a distinct diagnostic hallmark. Therefore, to identify diagnostic markers for ANKL, we analyzed the clinical data and laboratory findings obtained for 20 patients with ANKL. METHODS From January 2000 to July 2007, 20 patients were diagnosed with ANKL on the basis of bone marrow studies. We retrospectively analyzed the clinical features and laboratory findings, including the complete blood count, Epstein-Barr virus status, immunophenotype, and the cytogenetic results. RESULTS The subjects included 6 women and 14 men (median age, 44 yr; range, 2-70 yr). Cytogenetic studies were performed in 18 patients, and karyotypic abnormalities were observed in 9 patients (50%). None of the cytogenetic abnormalities were constantly observed in all the patients. However, 6q abnormalities were observed in 4 patients (4/18, 22%). The immunophenotype of the leukemic NK-cells was cytoplasmic CD3(+), surface CD3(-), CD16/56(+), CD2(+), and CD5(-). Notably, the CD7 antigen was absent in 10 patients (50%). When the CD7 loss was combined with cytogenetic abnormalities, clonal markers could be identified in 75% of the ANKL cases. CONCLUSIONS The CD7 antigen loss was frequently observed in our series of ANKL patients. In conjunction with the cytogenetic findings, this characteristic immunophenotypic finding can serve as a reliable marker for the timely diagnosis of ANKL. Therefore, immunophenotypic analysis of CD7 expression should be included in the diagnosis of NK cell neoplasms.

JAK2 V617F and MPL W515L/K Mutations in Korean Patients with Essential Thrombocythemia

JAK2 V617F and MPL W515L/K mutations have been reported in approximately 50% and 5% of the patients with essential thrombocythemia (ET), respectively. We investigated the frequency of MPL W515L/K mutations in a series of consecutive patients with ET and post-essential thrombocythemia myelofibrosis (post-ET MF). The study subjects were 63 patients diagnosed either with ET (N=59) or post-ET MF (N=4) at our institution between June 2006 and February 2010. Among them, 35 (55.6%) had the JAK2 V617F mutation. MPL W515L/K mutations were detected by direct sequencing analyses of exon 10, and 2 patients were found to harbor the following MPL mutations: W515L in 1 patient with ET and W515K in 1 patient with post-ET MF. Neither of the patients had the JAK2 V617F mutation. Thus, the frequency of MPL W515L/K mutation in Korean patients with ET/post-ETMF was 3.2% (2/63) and that in JAK2 V617F-negative ET/post-ET MF was 7.1% (2/28) [corrected]. This is the first study to report the frequency of JAK2 V617F and MPL W515L/K mutations in Korean patients with ET/post-ET MF.

Isobutyryl-CoA dehydrogenase deficiency with a novel ACAD8 gene mutation detected by tandem mass spectrometry newborn screening.

Isobutyryl-CoA dehydrogenase (IBD) is an enzyme involved in the catabolism of the branched-chain amino acid valine. IBD deficiency is a very rare metabolic disorder, whereby only a few cases have been reported thus far. Recently, we observed a Korean newborn boy with elevated concentration of C4-acylcarnitine detected by tandem mass spectrometry neonatal screening. Subsequent sequencing analysis of ACAD8 gene revealed that he was compound heterozygous for a novel mutation involving the first codon (c.3G>T; Met1Ile) and a previously reported mutation (c.1000C>T; Arg334Cys). To the best of our knowledge, this is the first confirmed case of IBD deficiency based on biochemical and genetic studies not only in Korea but also in Asia.

Prevalence of overt myeloproliferative neoplasms and JAK2 V617F mutation in Korean patients with splanchnic vein thrombosis

Introduction:  Myeloproliferative neoplasm (MPN) is known to be a major risk factor of splanchnic vein thrombosis (SVT). Recent studies revealed that a significant proportion of patients with SVT harbor a gain‐of‐function mutation in the JAK2 gene (V617F) with or without MPN. In this study, the authors investigated the prevalence of MPN and JAK2 V617F mutation in Korean patients with SVT.

A Novel Mutation W252X in the WAS Gene in a Korean Patient with Wiskott-Aldrich Syndrome

Wiskott-Aldrich syndrome (WAS) is a primary immunodeficiency disorder characterized by recurrent infection, eczema, and microthrombocytopenia. WAS is inherited in an X-linked recessive pattern, and various mutations in the WAS gene on the X chromosome are the genetic basis of WAS. A 7-month-old Korean boy presented with recurrent bloody diarrhea, eczema, and persistent thrombocytopenia with small platelets. Direct sequence analysis of the entire coding region of the WAS gene showed a novel nonsense mutation with a G-to-A substitution at the nucleotide position 756 on exon 8, leading to a premature termination at codon 252 (c.756G>A; p.W252X). Family study revealed that neither of the parents had the mutation, indicating the de novo occurrence of the mutation.