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1.  Characteristics of thyroid nodules in infant with congenital hypothyroidism 
Korean Journal of Pediatrics  2014;57(2):85-90.
This study aimed to assess the characteristics of thyroid nodules among infants diagnosed with congenital hypothyroidism.
A retrospective study of 660 infants (374 males, 286 females) diagnosed with congenital hypothyroidism was carried out at the Pediatric Endocrine Clinic in Soonchunhyang University Hospital, Korea, between May 2003 and February 2013. The average age at diagnosis was 1.16±1.68 months.
Of the 28 patients (4.2%) with thyroid nodules, 17 (2.6%) had cystic thyroid nodules and 11 (1.6%) had solid thyroid nodules. There were no significant differences in gender or age between congenital hypothyroidism patients who hadthyroid nodules and those who did not. All nodules were asymptomatic. The average age at diagnosis of congenital hypothyroidism with nodules was 1.42±1.39 months. All detected nodules measured less than 1 cm in diameter. Twenty-two of the 28 infants (78.6%) had only one nodule, while multiple nodules were found in 6 infants (21.4%). Of the 28 infants diagnosed with nodules, 16 underwent thyroid ultrasonography during follow-up and 8 of them (50%) showed no signs of nodules at thyroid ultrasonography.
The prevalence of thyroid nodules in infants with congenital hypothyroidism was 4.2%. Most thyroid nodules were small in size and benign, disappearing during follow-up observation. We therefore conclude that thyroid nodules in infants with congenital hypothyroidism can simply be observed and do not require direct treatment.
PMCID: PMC3965800  PMID: 24678333
Thyroid nodule; Congenital hypothyroidism; Ultrasonography; Infant
2.  Microfluidic Fabrication of Cell Adhesive Chitosan Microtubes 
Biomedical microdevices  2013;15(3):10.1007/s10544-013-9746-z.
Chitosan has been used as a scaffolding material in tissue engineering due to its mechanical properties and biocompatibility. With increased appreciation of the effect of micro- and nanoscale environments on cellular behavior, there is increased emphasis on generating microfabricated chitosan structures. Here we employed a microfluidic coaxial flow-focusing system to generate cell adhesive chitosan microtubes of controlled sizes by modifying the flow rates of a chitosan pre-polymer solution and phosphate buffered saline (PBS). The microtubes were extruded from a glass capillary with a 300 μm inner diameter. After ionic crosslinking with sodium tripolyphosphate (TPP), fabricated microtubes had inner and outer diameter ranges of 70-150 μm and 120-185 μm. Computational simulation validated the controlled size of microtubes and cell attachment. To enhance cell adhesiveness on the microtubes, we mixed gelatin with the chitosan pre-polymer solution and adjusted the pH values of the chitosan pre-polymer solution with gelatin and TPP. During the fabrication of microtubes, fibroblasts suspended in core PBS flow adhered to the inner surface of chitosan-gelatin microtubes. To achieve physiological pH values, we adjusted pH values of chiotsan pre-polymer solution and TPP. In particular, we were able to improve cell viability to 92% with pH values of 5.8 and 7.4 for chitosan and TPP solution respectively. Cell culturing for three days showed that the addition of the gelatin enhanced cell spreading and proliferation inside the chitosan-gelatin microtubes. The microfluidic fabrication method for ionically crosslinked chitosan microtubes at physiological pH can be compatible with a variety of cells and used as a versatile platform for microengineered tissue engineering.
PMCID: PMC3651799  PMID: 23355068
Chitosan-Gelatin Hydrogel; Microfluidic Flow-Focusing; Microtube; Cell Viability
3.  Pigmented villonodular synovitis of the temporomandibular joint - computed tomography and magnetic resonance findings: a case report 
Pigmented villonodular synovitis (PVNS) is a benign but locally aggressive and destructive disease originating in the synovial membranes. It is a proliferative disorder of unknown etiology. Involvement of the temporomandibular joint (TMJ) is very rare. Computed tomography clearly reveals areas of lytic bone erosion and sclerosis, and also clearly defines the extent of the tumor which is the focal areas of hyperdensity within the soft-tissue mass. Magnetic resonance images invariably show profound hypointensity on both T1- and T2-weighted sequences due to hemosiderin pigmentation. Additionally, high signal intensity on T2-weighted images may indicate cystic loculation of the joint fluid. This case study describes a rare case of PVNS of the TMJ with bone destruction of the mandibular condyle. Complete surgical excision of the lesion was performed through a preauricular approach with temporal extension. During the 10-year follow-up, two more operations were performed due to local recurrence and the fracture of the reconstruction plate. Total joint reconstruction with Biomet was finally performed, and the absence of disease was confirmed with a biopsy report showing fibrosis with hyalinization and mild inflammation of the excised soft tissue from the old lesion.
PMCID: PMC4095812  PMID: 25045642
Temporomandibular joint; Pigmented villonodular synovitis; Mandibular reconstruction
4.  Primary Burkitt's Lymphoma in the Nasal Cavity and Paranasal Sinuses 
Burkitt's lymphoma is a highly aggressive small B-cell lymphoma. The treatment of choice is complex chemotherapy. As a rare tumor in the head and neck area, Burkitt's lymphoma usually involves cervical lymph nodes, and only fewer than 25% of cases involves extranodal regions. Involvement of the paranasal sinuses has been reported in only 14 cases in the past century. We describe here two patients with rare, sporadic, American type Burkitt's lymphoma involving the nasal cavity and paranasal sinuses manifesting nasal obstruction. We also review clinical and histological features of Burkitt's lymphoma.
PMCID: PMC3781233  PMID: 24069523
Lymphoma; Burkitt lymphoma; Nasal cavity; Paranasal sinus
5.  Characterization of genes required for the pathogenicity of Pectobacterium carotovorum subsp. carotovorum Pcc21 in Chinese cabbage 
Microbiology  2013;159(Pt 7):1487-1496.
Pectobacterium carotovorum subsp. carotovorum is a well-known plant pathogen that causes severe soft rot disease in various crops, resulting in considerable economic loss. To identify pathogenicity-related factors, Chinese cabbage was inoculated with 5314 transposon mutants of P. carotovorum subsp. carotovorum Pcc21 derived using Tn5 transposon mutagenesis. A total of 35 reduced-virulence or avirulent mutants were isolated, and 14 loci were identified. The 14 loci could be functionally grouped into nutrient utilization (pyrD, purH, purD, leuA and serB), production of plant cell-wall-degrading enzymes (PCWDEs) (expI, expR and PCC21_023220), motility (flgA, fliA and flhB), biofilm formation (expI, expR and qseC), susceptibility to antibacterial plant chemicals (tolC) and unknown function (ECA2640). Among the 14 genes identified, qseC, tolC and PCC21_023220 are novel pathogenicity factors of P. carotovorum subsp. carotovorum involved in biofilm formation, phytochemical resistance and PCWDE production, respectively.
PMCID: PMC3749726  PMID: 23676432
6.  Complete Genome Sequence of Pectobacterium carotovorum subsp. carotovorum Bacteriophage My1 
Journal of Virology  2012;86(20):11410-11411.
Pectobacterium carotovorum subsp. carotovorum, a member of the Enterobacteriaceae family, is an important plant-pathogenic bacterium causing significant economic losses worldwide. P. carotovorum subsp. carotovorum bacteriophage My1 was isolated from a soil sample. Its genome was completely sequenced and analyzed for the development of an effective biological control agent. Sequence and morphological analyses revealed that phage My1 is a T5-like bacteriophage and belongs to the family Siphoviridae. To date, there is no report of a Pectobacterium-targeting siphovirus genome sequence. Here, we announce the complete genome sequence of phage My1 and report the results of our analysis.
PMCID: PMC3457130  PMID: 22997426
7.  Autophagy induction by tetrahydrobiopterin deficiency 
Autophagy  2011;7(11):1323-1334.
Tetrahydrobiopterin (BH4) deficiency is a genetic disorder associated with a variety of metabolic syndromes such as phenylketonuria (PKU). In this article, the signaling pathway by which BH4 deficiency inactivates mTORC1 leading to the activation of the autophagic pathway was studied utilizing BH4-deficient Spr-/- mice generated by the knockout of the gene encoding sepiapterin reductase (SR) catalyzing BH4 synthesis. We found that mTORC1 signaling was inactivated and autophagic pathway was activated in tissues from Spr-/- mice. This study demonstrates that tyrosine deficiency causes mTORC1 inactivation and subsequent activation of autophagic pathway in Spr-/- mice. Therapeutic tyrosine diet completely rescued dwarfism and mTORC1 inhibition but inactivated autophagic pathway in Spr-/- mice. Tyrosine-dependent inactivation of mTORC1 was further supported by mTORC1 inactivation in Pahenu2 mouse model lacking phenylalanine hydroxylase (Pah). NIH3T3 cells grown under the condition of tyrosine restriction exhibited autophagy induction. However, mTORC1 activation by RhebQ64L, a positive regulator of mTORC1, inactivated autophagic pathway in NIH3T3 cells under tyrosine-deficient conditions. In addition, this study first documents mTORC1 inactivation and autophagy induction in PKU patients with BH4 deficiency.
PMCID: PMC3242797  PMID: 21795851
tetrahydrobiopterin; autophagy; mTORC1; tyrosine; phenylalanine; phenylketonuria; Akt; AMPK
8.  Clinical characteristics of 2009 pandemic influenza A (H1N1) infection in children and the performance of rapid antigen test 
Korean Journal of Pediatrics  2011;54(10):405-408.
In autumn 2009, the swine-origin influenza A (H1N1) virus spread throughout South Korea. The aims of this study were to determine the clinical characteristics of children infected by the 2009 H1N1 influenza A virus, and to compare the rapid antigen and real-time polymerase chain reaction (PCR) tests.
We conducted a retrospective review of patients ≥18 years of age who presented to Soonchunhyang University Hospital in Seoul with respiratory symptoms, including fever, between September 2009 and January 2010. A real-time PCR test was used to definitively diagnose 2009 H1N1 influenza A infection. Medical records of confirmed cases were reviewed for sex, age, and the time of infection. The decision to perform rapid antigen testing was not influenced by clinical conditions, but by individual factors such as economic conditions. Its sensitivity and specificity were evaluated compared to real-time PCR test results.
In total, 934 patients tested positive for H1N1 by real-time PCR. The highest number of patients (48.9%) was diagnosed in November. Most patients (48.2%) were aged between 6 and 10 years. Compared with the H1N1 real-time PCR test results, the rapid antigen test showed 22% sensitivity and 83% specificity. Seventy-eight patients were hospitalized for H1N1 influenza A virus infection, and fever was the most common symptom (97.4%).
For diagnosis of 2009 H1N1 influenza A virus infection, the rapid antigen test was inferior to the real-time PCR test in both sensitivity and specificity. This outcome suggests that the rapid antigen test is inappropriate for screening.
PMCID: PMC3250593  PMID: 22232622
Influenza A virus; H1N1 subtype; Rapid antigen test; Polymerase chain reaction; Child
9.  Clinical, Biochemical and Genetic Analyses in Two Korean Patients with Medium-chain Acyl-CoA Dehydrogenase Deficiency 
Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is an autosomal recessive hereditary metabolic disorder of mitochondrial fatty acid β-oxidation. It is characterized by hypoketotic hypoglycemia, hyperammonemia, seizure, coma, and sudden infant death syndrome-like illness. The most frequently isolated mutation in the acyl-CoA dehydrogenase, medium-chain (ACADM) gene of Caucasian patients with MCADD is c.985A>G, but ethnic variations exist in the frequency of this mutation. Here, we describe 2 Korean pediatric cases of MCADD, which was detected during newborn screening by tandem mass spectrometry and confirmed by molecular analysis. The levels of medium-chain acylcarnitines, including octanoylcarnitine (C8), hexanoylcarnitine (C6), and decanoylcarnitine (C10), were typically elevated. Molecular studies revealed that Patient 1 was a compound heterozygote for c.449_452delCTGA (p.Thr150ArgfsX4) and c.461T>G (p.L154W) mutations, and Patient 2 was a compound heterozygote for c.449_452delCTGA (p.Thr150ArgfsX4) and c.1189T>A (p.Y397N) mutations. We detected asymptomatic patients with MCADD by using a newborn screening test and confirmed it by ACADM mutation analysis. This report presents evidence of the biochemical and molecular features of MCADD in Korean patients and, to the best of our knowledge, this is the first report of the c.461T>G mutation in the ACADM gene.
PMCID: PMC3111034  PMID: 21239873
Medium-chain acyl-CoA dehydrogenase deficiency (MCADD); ACADM; Novel mutation
10.  Regulation of the Vibrio vulnificus hupA Gene by Temperature Alteration and Cyclic AMP Receptor Protein and Evaluation of Its Role in Virulence▿  
Infection and Immunity  2009;77(3):1208-1215.
Availability of free iron is extremely limited in the mammalian host, and the acquisition of iron in the host is essential for successful infection by pathogenic bacteria. Expression of many genes involved in acquiring iron is regulated in response to the level of iron availability, and iron regulation is mediated by Fur. In this study, cellular levels of Vibrio vulnificus HupA, a heme receptor protein, and the hupA transcript were found to increase in cells grown at 40°C compared to cells grown at 30°C. The results suggested that change in growth temperature, in addition to iron availability, is an environmental cue controlling the expression of the hupA gene. The influence of global regulatory proteins on the expression of hupA was examined, and the cyclic AMP receptor protein (CRP) was found to activate the expression of hupA at the transcriptional level. CRP exerts its effects by directly binding to DNA upstream of the hupA promoter PhupA, and a CRP binding site, centered at 174 bp upstream of the transcription start site, was identified by a DNase I protection assay. Finally, a hupA mutant showed reduced virulence in mice and in tissue cultures, in which growth of the hupA mutant was impaired, indicating that HupA of V. vulnificus is essential for survival and multiplication during infection.
PMCID: PMC2643628  PMID: 19139193
11.  Mutation analysis of PAH gene and characterization of a recurrent deletion mutation in Korean patients with phenylketonuria 
Experimental & Molecular Medicine  2008;40(5):533-540.
Phenylketonuria (PKU; MIM 261600) is an autosomal recessive metabolic disorder caused by a deficiency of phenylalanine hydroxylase (PAH; EC Point mutations in the PAH gene are known to cause PKU in various ethnic groups, and large deletions or duplications account for up to 3% of the PAH mutations in some ethnic groups. However, a previous study could not identify ~14% of the mutant alleles by sequence analysis in Korean patients with PKU, which suggests that large deletions or duplication might be frequent causes of PKU in Koreans. To test this hypothesis, we performed multiplex ligation-dependent probe amplification (MLPA) for the identification of uncharacterized mutant alleles after PAH sequence analysis of 33 unrelated Korean patients with PKU. Bi-directional sequencing of the PAH exons and flanking intronic regions revealed 27 different mutations, including four novel mutations (two missense and two deletion mutations), comprising 57/66 (86%) mutant alleles. MLPA identified a large deletion that encompassed exons 5 and 6 in four patients, another large deletion that extended from exon 4 to exon 7 in one patient, and a duplication of exon 4 in one patient. Chromosomal walking characterized the deletion breakpoint of the most common large deletion that involved exons 5 and 6 (c.456_706+138del). The present study shows that the allelic frequency of exon deletion or duplication is 9% (6/66) in Korean PKU patients, which suggests that these mutations may be frequent causes of PKU in Korean subjects.
PMCID: PMC2679362  PMID: 18985011
Asian continental ancestry group; phenylketonurias; phenylalanine hydroxylase; sequence deletion

Results 1-11 (11)