Heon-Seok Han

Prevalence and genetic characterization of respiratory syncytial virus (RSV) in hospitalized children in Korea

Human respiratory syncytial virus (HRSV) is the most common respiratory pathogen among infants and young children. To investigate the prevalence and genetic characteristics of HRSVs circulating in South Korea, we analyzed medical records of patients and performed molecular analysis of the G-protein gene of viruses detected from nasopharyngeal aspirates (NPA) of admitted patients at the Pediatrics Department of Chungbuk National University Hospital from April 2008 to April 2010. Epidemiological data revealed that the prevalence of HRSV infection was high during both winter seasons (October 2008 to February 2009 and November 2009 to February 2010). Of the 297 positive NPA specimens from infants or children tested, 67% were identified as HRSV-A while 33% were HRSV-B. The HRSV subgroup B was the most dominant in December 2008, but its dominance was dramatically replaced by HRSV subgroup A strains by February 2009. Phylogenetic analysis of the G protein sequences of HRSVs revealed novel genotypes within the HRSV-A (genotype CB-A) and B (genotypes BA11 and CB-B) subgroups in South Korea in addition to other strains identified in other countries. Molecular analysis also revealed genetic variability at the C-terminal end of the G proteins of the two HRSV subgroups, suggesting selection pressure in this region, which may potentially impact immune recognition. This is the first report of these HRSV variants in South Korea, indicating active genetic evolution of HRSV strains. Therefore, this study provides information on the molecular epidemiology of current HRSVs in the country and presents data for comparative analysis with other HRSV strains circulating worldwide.

Nutritional Status of Vitamin D and the Effect of Vitamin D Supplementation in Korean Breast-fed Infants

We investigated the vitamin D status and the effect of vitamin D supplementation in Korean breast-fed infants. The healthy term newborns were divided into 3 groups; A, formula-fed; B, breast-fed only; S, breast-fed with vitamin D supplementation. We measured serum concentrations of vitamin D (25OHD3), calcium (Ca), phosphorus (P), alkaline phosphatase (AP), intact parathyroid hormone (iPTH) and bone mineral density (BMD) at 6 and 12 months of age. Using questionnaires, average duration of sun-light exposure and dietary intake of vitamin D, Ca and P were obtained. At 6 and 12 months of age, 25OHD3 was significantly higher in group S than in group B (P<0.001). iPTH was significantly lower in group S than in group B at 6 months (P=0.001), but did not differ at 12 months. Regardless of vitamin D supplementation, BMD was lower in group B and S than in group A (P<0.05). Total intake of vitamin D differed among 3 groups (P<0.001, A>S>B), but total intake of Ca and P were higher in group A than in group B and S (P<0.001). In conclusion, breast-fed infants show lower vitamin D status and bone mineralization than formula-fed infants. Vitamin D supplementation (200 IU/day) in breast-fed infants increases serum 25-OH vitamin D3, but not bone mineral density.

A 5-yr follow-up nerve conduction study for the detection of subclinical diabetic neuropathy in children with newly diagnosed insulin-dependent diabetes mellitus.

Lee S‐S, Han H‐H, Kim H. A 5‐yr follow‐up nerve conduction study for the detection of subclinical diabetic neuropathy in children with newly diagnosed insulin‐dependent diabetes mellitus. Pediatric Diabetes 20XX: 00: 000–000

Zinc status and growth of Korean infants fed human milk, casein-based, or soy-based formula: three-year longitudinal study

To evaluate the effect of feeding methods on growth and zinc nutritional status of infants early in life, we monitored from birth to 36 months in 51 infants who were exclusively fed human milk (HM, n = 20), casein-based formula (CBF, n = 12), or soy-based formula (SBF, n = 19) during the first five months of life. Zinc status was assessed by analyzing serum zinc concentrations and zinc intakes. Zinc contents in HM and formulas were measured. Zinc intake was estimated by weighing infants before and after feeding in the HM group and by collecting formula-intake records in the CBF and SBF groups. After solid foods were introduced, all foods consumed were also included to estimate zinc intake. The growth of infants in all groups was similar to that established for normal Korean infants. Human milk zinc concentrations declined as lactation progressed. Zinc concentrations in all formulas tested in this study were higher than HM and were also higher than those claimed by the manufacturers. During the first twelve months, mean serum zinc concentrations of infants were similar in all groups, although infants in the HM group consistently had the lowest zinc intake among the groups, and the overall zinc intake in infants fed SBF was highest. This finding could be explained by the different zinc bioavailability of HM and formulas. In conclusion, infants fed HM, CBF or SBF has normal growth up to three years of age, although HM contained the lowest zinc concentration followed by CBF, then SBF.

Emergence of Amantadine-Resistant H3N2 Avian Influenza A Virus in South Korea

ABSTRACT We found a relatively high frequency of unique amantadine-resistant H3N2 and H9N2 avian influenza viruses (Val27Ile on M2 protein) isolated from live poultry markets in South Korea and confirmed that a Val27Ile single substitution in the M2 protein is enough to acquire the amantadine resistance phenotype by using reverse-genetically created human-avian reassortant viruses.

Molecular characterization and phylogenetic analysis of H3N2 human influenza A viruses in Cheongju, South Korea.

To investigate the genetic characteristics of human influenza viruses circulating in Chungbuk province, we tested 510 clinical samples of nasopharyngeal suction from pediatric patients diagnosed with respiratory illness between June 2007 and June 2008. Genetic characterization of the HA genes of H3N2 isolates indicated the relative higher similarity to A/Virginia/04/07 (99.6%) rather than that of A/Wisconsin/67/2005 (98.4%), a Northern Hemisphere 2007∼2008 vaccine strain, based on amino acid sequences. We found several altered amino acids at the H3 HA1 antigenic sites compared with the vaccine strain; K140I at site A, K158R at site B, and K173N (H471) or K173Q, and S262N at site E, but there was no antigenic shift among the H3N2 viruses. Interestingly, A/Cheongju/H383/08 and A/Cheongju/H407/08 isolates had single amino acid substitution at D151G on the catalytic site of the N2 NA while A/Cheongju/H412/08 and A/Cheongju/ H398/07 isolates had one amino acid deletion at residue 146. Furthermore, we found that 25% (3 out of 12 isolates) of the H3N2 subtype viruses had the amino acid substitution at position 31 on the M2 protein (Aspartic acid to Asparagine) and confirmed their drug-resistance by biological assays. Taken together, the results of this study demonstrated continuous evolutions of human H3N2 viruses by antigenic drift and also highlighted the need to closely monitor antigenic drug resistance in influenza A viruses to aid in the early detection of potentially pandemic strains, as well as underscore the need for new therapeutics.

Folate contents in human milk and casein-based and soya-based formulas, and folate status in Korean infants.

We assessed folate nutritional status from birth to 12 months in fifty-one infants who were fed human milk (HM; n 20), casein-based formula (CBF; n 12) or soya-based formula (SBF; n 19). Folate contents in ninety-five HM samples obtained from twenty mothers for the first 6-month period and twelve CBF and nineteen SBF samples were measured by bioassay after trienzyme extraction. Folate intake was estimated by weighing infants before and after feeding in the HM group and by collecting formula intake records in the formula-fed groups. After solid foods were introduced, all foods consumed were included to estimate folate intake. Serum folate and total homocysteine (tHcy) concentrations were determined at 5 and 12 months of age, and infant growth was monitored for the first 12 months. Mean HM folate contents ranged from 201 to 365 nmol/l with an overall mean of 291 nmol/l, and the contents peaked at 2 months postpartum. HM folate contents were higher than those reported in North America. Folate contents in CBF and SBF were markedly higher than those in HM and those claimed on the product labels. The overall folate intakes in formula-fed infants were significantly higher than those in HM-fed infants, and this was associated with significantly higher folate and lower tHcy in formula-fed infants than HM-fed infants at 5 months. At 12 months, serum folate was significantly higher in the SBF group than the other groups, whereas serum tHcy and overall growth were similar among all groups.

Reduced Frequencies of Peripheral Interferon-γ-Producing CD4+ and CD4– Cells during Acute Kawasaki Disease

Background: This study was performed to analyze the frequencies of peripheral interferon (IFN)-γ-producing cells at the single-cell level and to determine concentrations of circulating IFN-γ in the acute and subacute phases of Kawasaki disease (KD). Methods: Ten patients with KD were studied and seven healthy children were selected as control subjects. Using immunofluorescent detection of intracellular IFN-γ in CD4-positive and CD4-negative cells, the frequencies of IFN-γ-producing cells in peripheral blood mononuclear cells were studied. Circulating IFN-γ levels were measured by enzyme-linked immunosorbent assay. Results: The frequencies of peripheral blood CD4+ and CD4– IFN-γ-producing cells in acute-phase KD patients were significantly lower than in subacute-phase KD patients and control children (p < 0.05). CD4– cells, thought to be mainly composed of CD8+ cells, appeared to be more responsible for the reduced frequencies of total IFN-γ-producing cells than CD4+ cells. There were, however, no differences in the frequencies of IFN-γ-producing cells between KD patients in the subacute phase and control children. In contrast, serum IFN-γ levels were higher in KD patients in the acute phase than in the subacute phase (p < 0.05). Conclusions: The above results show increased levels of circulating IFN-γ and decreased emergence of peripheral IFN-γ-producing cells in acute KD patients, suggesting transient infiltration of activated IFN-γ-producing cells into the inflammatory sites during acute KD. These findings also support the hypothesis that IFN-γ plays an important role in the pathogenesis of KD-related vasculitis.

Tuberculous Pericarditis Presenting as Multiple Free Floating Masses in Pericardial Effusion

Pericarditis is a rare manifestation of tuberculosis (Tb) in children. A 14-yr-old Korean boy presented with cardiac tamponade during treatment of pulmonary tuberculosis. He developed worsening anemia and persistent fever in spite of anti-tuberculosis medications. Echocardiography found free floating multiple discoid masses in the pericardial effusion. The masses and exudates were removed by pericardiostomy. The masses were composed of pink, amorphous meshwork of threads admixed with degenerated red blood cells and leukocytes with numerous acid-fast bacilli, which were confirmed as Mycobacterium species by polymerase chain reaction. The persistent fever and anemia were controlled after pericardiostomy. This is the report of a unique manifestation of Tb pericarditis as free floating masses in the effusion with impending tamponade.

Early discontinuation of thyroxine therapy is possible in most very low‐birthweight infants with hypothyroidism detected by screening

To determine the feasibility of discontinuing thyroid hormone treatment earlier than recommended by the current guidelines for congenital hypothyroidism.