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In this review, we discuss violacein and prodigiosin, two chromogenic bacterial secondary metabolites that have diverse biological activities. Although both compounds were “discovered” more than seven decades ago, interest into their biological applications has grown in the last two decades, particularly driven by their antimicrobial and anticancer properties. These topics will be discussed in the first half of this review. The latter half delves into the current efforts of groups to produce these two compounds. This includes in both their native bacterial hosts and heterogeneously in other bacterial hosts, including discussing some of the caveats related to the yields reported in the literature, and some of the synthetic biology techniques employed in this pursuit.

Recent years have witnessed increased interest in systems that are capable of supporting multistep chemical processes without the need for manual handling of intermediates. These systems have been based either on collections of batch reactors1 or on flow-chemistry designs2–4, both of which require considerable engineering effort to set up and control. Here we develop an out-of-equilibrium system in which different reaction zones self-organize into a geometry that can dictate the progress of an entire process sequence. Multiple (routinely around 10, and in some cases more than 20) immiscible or pairwise-immiscible liquids of different densities are placed into a rotating container, in which they experience a centrifugal force that dominates over surface tension. As a result, the liquids organize into concentric layers, with thicknesses as low as 150 micrometres and theoretically reaching tens of micrometres. The layers are robust, yet can be internally mixed by accelerating or decelerating the rotation, and each layer can be individually addressed, enabling the addition, sampling or even withdrawal of entire layers during rotation. These features are combined in proof-of-concept experiments that demonstrate, for example, multistep syntheses of small molecules of medicinal interest, simultaneous acid–base extractions, and selective separations from complex mixtures mediated by chemical shuttles. We propose that ‘wall-less’ concentric liquid reactors could become a useful addition to the toolbox of process chemistry at small to medium scales and, in a broader context, illustrate the advantages of transplanting material and/or chemical systems from traditional, static settings into a rotating frame of reference. In a rotating reactor, immiscible or pairwise-immiscible liquids organize into stable but internally agitated concentric layers, enabling multistep syntheses and separations of reaction mixtures.

Maternal behaviors benefit the survival of young, contributing directly to the mother’s reproductive fitness. An extreme form of this is seen in matriphagy, when a mother performs the ultimate sacrifice and offers her body as a meal for her young. Whether matriphagy offers only a single energy-rich meal or another possible benefit to the young is unknown. Here, we characterized the toxicity of a bacterial secondary metabolite, namely, violacein, in Caenorhabditis elegans and found it is not only toxic towards adults, but also arrests growth and development of C. elegans larvae. To counteract this, C. elegans resorted to matriphagy, with the mothers holding their eggs within their bodies and hatching the young larvae internally, which eventually led to the mothers’ death. This violacein-induced matriphagy alleviated some of the toxic effects of violacein, allowing a portion of the internally-hatched young to bypass developmental arrest. Using genetic and pharmacological experiments, we found the consumption of oleate, a monounsaturated fatty acid produced by the mother, during matriphagy is partially responsible. As such, our study provides experimental evidence of why such a drastic and peculiar maternal behavior may have arisen in nematode natural habitats.

This study describes Chromobacterium violaceum's use of extracellular membrane vesicles (MVs) to both solubilize and transport violacein to other microorganisms. Violacein is a hydrophobic bisindole with known antibiotic activities against other microorganisms. Characterization of the MVs found they carried more violacein than protein (1.37 ± 0.19-fold), suggesting they may act as a reservoir for this compound. However, MVs are not produced in response to violacein - a ΔvioA isogenic mutant, which is incapable of making violacein, actually produced significantly more MVs (3.2-fold) than the wild-type strain. Although violacein is insoluble in water (Log Poctanol:water = 3.34), 79.5% remained in the aqueous phase when it was present within the C. violaceum MVs, an increase in solubility of 1740-fold. Moreover, tests with a strain of Staphylococcus aureus showed MV-associated violacein is bactericidal, with 3.1 mg/l killing 90% of S. aureus in 6 h. Tests with the ΔvioA MVs found no loss in the S. aureus viability, even when its MVs were added at much higher concentrations, demonstrating violacein is the active component within the wild-type MVs. In conclusion, our study clearly demonstrates C. violaceum produces MVs and uses them as vehicles to solubilize violacein and transport this hydrophobic antibiotic to other microbes.

As mankind evaluates moving toward permanently inhabiting outer space and other planetary bodies, alternatives to antibiotic that can effectively control drug-resistant pathogens are needed. The activity of one such alternative, Bdellovibrio bacteriovorus HD100, was explored here, and was found to be as active or better in simulated microgravity (SMG) conditions as in flask and normal gravity (NG) cultures, with the prey viabilities decreasing by 3- to 7-log CFU/mL in 24 h. The activity of B. bacteriovorus HD100 under SMG was also appraised with three different carbapenem- and colistin-resistant pathogenic bacterial strains. In addition to being more efficient at killing two of these pathogens under SMG conditions (with losses of 5- to 6-log CFU/mL), we also explored the ability of B. bacteriovorus HD100 to hydrolyze the carbapenem- and colistin-resistant gene pools, i.e., mcr-1, bla

Bdellovibrio bacteriovorus HD100 is a highly motile predatory bacterium that consumes other Gram-negative bacteria for its sustenance. Here, we describe the impacts the media viscosity has both on the motility of predator and its attack rates. Experiments performed in polyethylene glycol (PEG) solutions, a linear polymer, found a viscosity of 10 mPa s (5% PEG) negatively impacted predation over a 24-h period. When the viscosity was increased to 27 mPa s (10% PEG), predation was nearly abolished. Tests with three other B. bacteriovorus strains, i.e., 109J and two natural isolates, found identical results. Short-term (2-h) experiments, however, found attack rates were improved in 1% PEG, which had a viscosity of 5.4 mPa s, using bioluminescent prey and their viabilities. In contrast, when experiments were performed in dextran, a branched polymer, no increase in predation was seen even though the viscosity was a comparable 5.1 mPa s. The enhanced attack rates in this solution coincided with a 31% increase in B. bacteriovorus HD100 swimming speeds (62 μm s-1 in 1% PEG vs. 47.5 μm s-1 in HEPES-salt).

Bdellovibrio-and-like organisms (BALOs) are a small group of bacteria that actively predate on other Gram-negative bacterial species. Although viewed mostly in a positive light, such as their potential use as living antibiotics to reduce pathogenic strain populations, several studies have also highlighted the need to control their activities, such as in the production of biodiesel. Consequently, this mini-review discusses research being conducted to characterize compounds and environmental settings that influence predation rates and the mechanisms by which they accomplish this, with a heavy emphasis on studies published within the last decade.Key points• This review discusses bacterial predators and factors impacting their activities. • Emphasis is on recent articles, particularly those discussing prey metabolites. • The implications on possible applications of bacterial predators are discussed.

Recent years have witnessed increased interest in systems that are capable of supporting multistep chemical processes without the need for manual handling of intermediates. These systems have been based either on collections of batch reactors

Predation of Chromobacterium piscinae by Bdellovibrio bacteriovorus HD100 was inhibited in dilute nutrient broth (DNB) but not in HEPES. Experiments showed that the effector responsible was present in the medium, as cell-free supernatants retained the ability to inhibit predation, and that the effector was not toxic to B. bacteriovorus. Violacein, a bisindole secondary metabolite produced by C. piscinae, was not responsible. Further characterization of C. piscinae found that this species produces sufficient concentrations of cyanide (202 µM) when grown in DNB to inhibit the predatory activity of B. bacteriovorus, but that in HEPES, the cyanide concentrations were negligible (19 µM). The antagonistic role of cyanide was further confirmed, as the addition of hydroxocobalamin, which chelates cyanide, allowed predation to proceed. The activity of cyanide against B. bacteriovorus was found to be twofold, depending on the life cycle stage of this predator. For the attack-phase predatory cells, cyanide caused the cells to lose motility and tumble, while for intraperiplasmic predators, development and lysis of the prey cell were halted. These findings suggest that cyanogenesis in nature may be employed by the bacterial strains that produce this compound to prevent and reduce their predation by B. bacteriovorus., IMPORTANCE Bacterial predators actively attack, kill, and enter the periplasm of susceptible Gram-negative bacteria, where they consume the prey cell components. To date, the activity of B. bacteriovorus HD100 has been demonstrated against more than 100 human pathogens. As such, this strain and others are being considered as potential alternatives or supplements to conventional antibiotics. However, the production of secondary metabolites by prey bacteria is known to mitigate, and even abolish, predation by bacterivorous nematodes and protists. With the exception of indole, which was shown to inhibit predation, the effects of bacterial secondary metabolites on B. bacteriovorus and its activities have not been considered. Consequently, we undertook this study to better understand the mechanisms that bacterial strains employ to inhibit predation by B. bacteriovorus HD100. We report here that cyanogenic bacterial strains can inhibit predation and show that cyanide affects both attack-phase predators and those within prey, i.e., in the bdelloplast.

Violacein is a bisindole antibiotic that is effective against Gram-positive bacteria while the bacterial predator, Bdellovibrio bacteriovorus HD100, predates on Gram-negative strains. In this study, we evaluated the use of both together against multidrug resistant pathogens. The two antibacterial agents did not antagonize the activity of the other. For example, treatment of Staphylococcus aureus with violacein reduced its viability by more than 2,000-fold with or without B. bacteriovorus addition. Likewise, predation of Acinetobacter baumannii reduced the viability of this pathogen by more than 13,000-fold, regardless if violacein was present or not. When used individually against mixed bacterial cultures containing both Gram-positive and Gram-negative strains, violacein and B. bacteriovorus HD100 were effective against only their respective strains. The combined application of both violacein and B. bacteriovorus HD100, however, reduced the total pathogen numbers by as much as 84,500-fold. Their combined effectiveness was also demonstrated using a 4-species culture containing S. aureus, A. baumannii, Bacillus cereus and Klebsiella pneumoniae. When used alone, violacein and bacterial predation reduced the total population by only 19% and 68%, respectively. In conjunction with each other, the pathogen viability was reduced by 2,965-fold (99.98%), illustrating the prospective use of these two antimicrobials together against mixed species populations.

This paper presents a dual-mode DC-DC buck converter using power transistor width scaling (PTWS) with a zero current detector to improve power efficiency under light load. The buck converter is operated in a dual mode, combining the switching frequency modulation (SFM) mode which uses the voltage controlled oscillator (VCO) under light load, with the PWM mode for heavy load. To enhance power efficiency under light load a PTWS scheme is employed, in which the inductor current is detected using a zero current detector (ZCD) and then used to select the gate size of the power switching transistor. The proposed circuit was designed using a Magnachip 0.35μm CMOS process. Simulation results shows that our proposed converter has 81.3% ∼ 93% power efficiency for output load currents of 10mA ∼ 250mA, which is a 5.3% improvement compared to a simple SFM-PWM dual mode and an 8.9% improvement compared to a PWM-only mode under a light load of 10mA, respectively.

Delta neutrophil index (DNI) has been reported to be useful in assessing the prognosis of suspected bacteraemia in adults. However, data in children are limited. The purpose of this study was to investigate the correlation between the DNI and bacteraemia in children and to compare DNI values between immunocompetent and immunocompromised hosts.We retrospectively collected data on 8593 children who underwent simultaneous blood culture and DNI testing. DNI was determined with a blood cell analyser (ADVIA 120, Siemens, Inc.). The children were divided into immunocompromised (n=664) and immunocompetent groups (n=7929).DNI was higher in the bacteraemia group than in the non-bacteraemia group (P0.001). According to the group, DNI was higher in immunocompromised than immunocompetent patients (P0.001). Within the immunocompromised group, there was no significant difference between the bacteraemia and non-bacteraemia subgroups due to a higher DNI as compared to the immunocompetent group.DNI could be an additional method for the early diagnosis of bacteraemia in children. However, the use of DNI for the prediction of bacteraemia in immunocompromised cases has limitations. Further studies on the usefulness of DNI according to specific diseases are needed.

A spray chrysanthemum cultivar 'Green Candy' was released by National Institute of Horticultural & Herbal Science, Rural Development Administration, in 2009. The cross between 'Yoko Ono', a spray chrysanthemum cultivar with light yellowish-green double type, and 'Green Bird', a spray chrysanthemum cultivar with vigorous and green double type, was made in Suwon in 2006. After the evaluation of the characteristics under shade culture in summer and retarding culture in spring and consecutive selection from 2007 to 2009, 'Green Candy' was selected finality. The natural flowering time of 'Green Candy' is October 28th, and it is possible to flower all year-round by shade and light culture. It has double flower type with green petals. The growth of plant is very vigorous and the color of the petals is stable when the variety is cultivated under high temperature conditions in summer season. The diameter of flower is 4.1 cm. The numbers of flower per stem and petals per flower are 12 and 217, respectively. The days for flowering under the short day treatment are about 58 and its vase life is 18.1 days in autumn season. 'Green Candy' was applied as No. 2010-212 on March 5, 2010 for variety protection and the plant variety protection rights have been registered as No. 3633 on August 2, 2011 at the Korea Seed and Variety Service.

One beguiling alternative to antibiotics for treating multi-drug resistant infections are Bdellovibrio-and-like-organisms (BALOs), predatory bacteria known to attack human pathogens. Consequently, in this study, the responses from four cell lines (three human and one mouse) were characterized during an exposure to different predatory bacteria, Bdellovibrio bacteriovorus HD100, Bacteriovorus BY1 and Bacteriovorax stolpii EB1. TNF-α levels were induced in Raw 264.7 mouse macrophage cultures with each predator, but paled in comparison to those obtained with E. coli. This was true even though the latter strain was added at an 11.1-fold lower concentration (p E. coli led to a significant (54%) loss in the Raw 264.7 murine macrophage viability while the predatory strains had no impact. Tests with various epithelial cells, including NuLi-1 airway, Caco2, HT29 and T84 colorectal cells, gave similar results, with E. coli inducing IL-8 production. The viabilities of the NuLi-1 and Caco-2 cells were slightly reduced (8%) when exposed to the predators, while T84 viability remained steady. In no cases did the predatory bacteria induce actin rearrangement. These results clearly demonstrate the gentle natures of predatory bacteria and their impacts on human cells.

Posterior reversible encephalopathy syndrome (PRES) is a clinico-neuroradiologic disease entity represented by characteristic magnetic resonance image (MRI) findings of subcortical/cortical hyperintensity in T2-weighted sequences, more often observed in parieto-occipital lobes, accompanied by clinical neurologic alterations. PRES is a rare central nervous system complication in childhood hematologic-oncologic patients and shows very different neurologic symptoms between patients, from numbness on extremities to generalized seizure. The etiology of PRES was not well known until these days. In this study, 8 patients with PRES were reviewed, retrospectively. There were 4 patients with acute lymphocytic leukemia, 1 with aplastic anemia, and 3 with solid tumors (1 patient each for neuroblastoma, Ewing sarcoma, and osteosarcoma). Allogeneic stem cell transplantation was performed in 2 patients. Immunosuppressive agents such as tacrolimus and cyclosporine A were used in 3 patients. One neuroblastoma patient was in immediate postoperative status. All patients experienced seizure attacks of different types and showed typical MRI findings. Follow-up MRIs revealed significant improvements. From this review, we might consider chemotherapy and surgery as additive causes for PRES other than immunosuppressive agents. Therefore, careful examination of the patients receiving chemotherapy and surgery was needed to find out this uncommon but good prognostic complication.

The 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) and the 13-valent pneumococcal conjugate vaccine (PCV13) replaced the 7-valent PCV (PCV7) in May 2010 in Korea. We investigated the dynamics of pneumococcal nasopharyngeal (NP) colonization in children with a respiratory illness before and after use of PHiD-CV and PCV13.From March 2009 to December 2012 NP secretions were obtained from 2176 children aged5 years with respiratory diseases. We used the multiplex polymerase chain reaction (PCR) technique to determine pneumococcal serotypes.Among the samples, 468 (21.5%) specimens were positive by multiplex PCR. The overall pneumococcal colonization rate remained stable during the 2009-2012 periods. The serotypes present in PCV7 and serotype 19A decreased in frequency from 36.8% and 26.4% in 2009 to 10.1% and 11.4% in 2012, respectively (χ(2) for trend, P0.001 and P = 0.007, respectively). The frequency of non-PCV13 serotypes increased from 36.8% in 2009 to 78.5% in 2012 (χ(2) for trend, P0.001). There was no significant difference in carriage rates of each serotype between groups of children that received PCV7, PHiD-CV, or PCV13.Compared with the period of PCV7 vaccination, overall carriage rate was not affected by the introduction of new PCVs. However, serotype distribution now consists mostly of non-vaccine serotypes. PCVs affect mucosal immunity against Streptococcus pneumoniae (SP) in NP carriage; but, global SP colonization seems to be maintained by replacement.

A violacein-producing bacterial strain was isolated and identified as a relative of Duganella violaceinigra YIM 31327 based upon phylogenetic analyses using the 16S rRNA, gyrB and vioA gene sequences and a fatty acid methyl ester (FAME) analysis. This new strain was designated D. violaceinigra str. NI28. Although these two strains appear related based upon these analyses, the new isolate was phenotypically different from the type strain as it grew 25% faster on nutrient media and produced 45-fold more violacein. When compared with several other violacein producing strains, including Janthinobacterium lividum, D. violaceinigra str. NI28 was the best violacein producer. For instance, the crude violacein yield with D. violaceinigra str. NI28 was 6.0 mg/OD at 24 hours, a value that was more than two-fold higher than all the other strains. Finally, the antibacterial activity of D. violaceinigra str. NI28 crude violacein was assayed using several multidrug resistant Staphylococcus aureus. Addition of 30 μM crude violacein led to a 96% loss in the initial S. aureus population while the minimum inhibitory concentration was 1.8 μM. Consequently, this novel isolate represents a phenotypic variant of D. violaceinigra capable of producing much greater quantities of crude violacein, an antibiotic effective against multidrug resistant S. aureus.

Purpose Methods for quick and reliable detection of Streptococcus pneumoniae are needed for the diagnosis of pneumococcal disease and vaccine studies. This study aimed to show that sequential multiplex polymerase chain reaction (PCR) is more efficient than conventional culture in achieving S. pneumoniae-positive results. Methods Nasopharyngeal (NP) secretions were obtained from 842 pediatric patients admitted with lower respiratory infections at Severance Children's Hospital in Korea between March 2009 and June 2010. For identification and serotype determination of pneumococci from the NP secretions, the secretions were evaluated via multiplex PCR technique with 35 serotype-specific primers arranged in 8 multiplex PCR sets and conventional bacteriological culture technique. Results Among the results for 793 samples that underwent both bacterial culture and PCR analysis for pneumococcal detection, 153 (19.3%) results obtained by PCR and 81 (10.2%) results obtained by conventional culture technique were positive for S. pneumoniae. The predominant serotypes observed, in order of decreasing frequency, were 19A (23%), 6A/B (16%), 19F (11%), 15B/C (5%), 15A (5%), and 11A (4%); further, 26% of the isolates were non-typeable. Conclusion As opposed to conventional bacteriological tests, PCR analysis can accurately and rapidly identify pneumococcal serotypes.

Purpose: The aim of this study was to investigate the clinical manifestations and laboratory characteristics of eosinophilic meningitis in Severance Children`s Hospital. Methods: We examined 6,335 children under the age of 18 years old who had visited the tertiary hospital in Seoul, Korea, and had received cerebrospinal study results between January 2007 and July 2012. The medical records of the patients identified as eosinophilic meningitis were retrospectively reviewed. Results: Eosinophilic meningitis was diagnosed in 39 patients (0.6%). The mean age was 6 years (range 0-18 years) and the sex ratio was 1.3:1 (22 males and 17 females). The underlying diseases and past history were neurologic disease (n

목 적 : 2000년이후human metapneumovirus (hMPV)는 하기도 호흡기 감염을 일으키는 주요 바이러스로 인식되고 있다. 급성 호흡기 감염으로 입원한 소아 환자들에서의 hMPV의 역학 및 임상적 특징, 그리고 혈액학적 특징 및 hMPV에 감염되지 않은 환자와의 비교, 중복 감염등을 통해 hMPV의 특징을 파악하고자 하였다. 방 법 : 2010년 2월부터 2012년 1월까지 급성 호흡기 증상으로 입원한 환아 1,554명의 비인두 흡인을 통해 객담 검체를 채취하여 RT-PCR을 시행 후 hMPV가 검출된 99명의 환아들의 임상 기록지를 후향적으로 검토하여 이들의 임상 증상 및 검사 소견을 분석 비교 하였다. 결 과 : 1,554명 중 1,004명(64.6%)에서 호흡기 바이러스가 검출되었다. 그 중 hMPV가 양성인 환자는 99명으로 양성 검체의 9.8%였다. hMPV에 감염된 환자의 평균 연령은 25.0개월이었으며 해마다 유행 정도는 다르나 4월부터 6월에 주로 발현하였으며 발열기간이 다른 바이러스 보다 길고 호흡기 증중을 보였으며, 천명(wheezing)이 특징적 임상 증상이었다. 진단으로 폐렴이 가장 많았지만, 12개월 이하의 연령군에서는 모세기관지염이 가장 흔하였다. 혈액학적 검사소견은 ESR (erythrocyte sedimentation rate), CRP (C-reactive protein) 모두 hMPV에 감염된 환자군에서 정상 범위 보다 상승된 소견을 보였다. hMPV의 단독 감염과 중복 감염을 비교해 보았을 때 임상증상 및 혈액 검사 소견에서 통계학적 차이를 보이지 않았다. 결론 : hMPV는 폐렴을 일으키는 주요 원인 바이러스이며 13개월 이상부터 48개월 이하의 연령에서 호발하며 평균 연령은 25개월이며 4월에서 6월까지 유행하는 양상을 보였다. 천명이 임상적 특징이며, hMPV에 대하여 우리나라에서의 보고는 점차 증가되고 있으나 아직은 생물학적, 유전학적 특징과 관련된 임상 분석이 더 필요하다. 【Purpose : The aim of this study was to determine the frequency, epidemiology and the clinical manifestation of human metapneumovirus (hMPV) infection in Korean children. Methods : From February 2010 to January 2012, we collected nasopharyngeal aspiration from 1,554 children who were hospitalized for acute lower respiratory tract infections at the Department of Pediatrics, Severance Children's Hospital. hMPV was detected by performing reverse transcriptase-polymerase chain reaction (RT-PCR). The medical records of the patients with positive results were retrospectively reviewed. Results : We detected hMPV in 99 of the 1,554 hospitalized children. The mean age of the hMPV infected children was 25 months, and 87% of the illnesses occurred between April and June. The most common diagnoses were pneumonia (73%) and bronchiolitis (16%). The clinical manifestations included cough, fever, respiratory distress, hoarseness, tachypnea, and wheezing. Coinfection with other respiratory viruses was found in 43 children (43%). Conclusion : hMPV is one of the major virus causing acute respiratory tract infection in the age between 13 months and 48 months old with peaks during April to June. Reports of hMPV in Korea has been increasing but additional studies are required to define the epidemiology and the extent of disease caused by hMPV to determine future development of this illness in Korean children.】

Nontyphoidal Salmonella are gram negative bacilli organism, which may induce systemic infection such as febrile enteritis, bacteremia, and osteomyelitis. Main route of infection is known as food but also possible through reptile, amphibian, and fish raised as pets in the house. There is no known cases report of Salmonella infection through pets in Korea and also rare in the overseas. We report 2 patients who visited Severance children's hospital with chief complaint of fever and diagnosed as nontyphoidal salmonellosis. Each case had a history of raising turtle or tropical fish with possibility of Salmonella infection through these pets. Increasing incidence of raising pet reptile and fish lately, contact precaution and proper prevention and control of Salmonella infection of these pets especially in children under 5 years old are necessary due to higher risk of serious complications of salmonellosis.

Purpose: Human bocavirus (hBoV), a recently discovered virus, has been detected in children with respiratory tract infections worldwide. The aim of this study was to analyze the frequency and molecular phylogeny of hBoV in the respiratory samples of children with acute respiratory tract infections in 2010. Methods: Nasopharyngeal samples were collected from 953 children with lower respiratory tract infections at Severance childrens hospital in Korea from January 2010 to December 2010. We applied the multiplex PCR technique for the identifi ' - cation of 12 respiratory viruses from the samples. Among the total specimens, hBoV positive samples were subjected to phylogenetic analysis by sequencing a fragment of the VP1/VP2 gene junction. Results: hBoVwas detected in 141 (14.8%) among 953 patients. The 61.7%of hBoV-positive samples were found to co-exist with other respiratory viruses. The results of phylogenetic analysis showed that all 141 hBoV-positive isolates were identified as hBoV 1, revealing a high similarity among the isolates (>98%). Conclusion: hBoV1 with minimal sequence variations circulated in children with acute respiratory infections during 2010. More research is needed to determine the clinical severity and outcomes of the minimal sequence variations. (Korean J Pediatr Infect Dis 2012;19:71-78)

' Purpose:As the number of children who attend child care centers has increased, concerns has increased about the effect of child day care on childhood illness. This study was conducted to examine the relationship between experience in child care and common infectious diseases in children under 5 years of age. Methods:Data were collected by surveying 1,000 respondents with children under age 5 through online interviews using a structured questionnaire. The contents of the survey were composed of demographic characteristics, child care facilities usage, experience in infectious diseases, and immunization status Results: Among the 1,000 children