CspB of an arctic bacterium, Polaribacter irgensii KOPRI 22228, confers extraordinary freeze-tolerance

ABSTRACT Freezing temperatures are a major challenge for life at the poles. Decreased membrane fluidity, uninvited secondary structure formation in nucleic acids, and protein cold-denaturation all occur at cold temperatures. Organisms adapted to polar regions possess distinct mechanisms that enable them to survive in extremely cold environments. Among the cold-induced proteins, cold shock protein (Csp) family proteins are the most prominent. A gene coding for a Csp-family protein, cspB, was cloned from an arctic bacterium, Polaribacter irgensii KOPRI 22228, and overexpression of cspB greatly increased the freeze-survival rates of Escherichia coli hosts, to a greater level than any previously reported Csp. It also suppressed the cold-sensitivity of an E. coli csp-quadruple deletion strain, BX04. Sequence analysis showed that this protein consists of a unique domain at its N-terminal end and a well conserved cold shock domain at its C-terminal end. The most common mechanism of Csp function in cold adaption is melting of the secondary structures in RNA and DNA molecules, thus facilitating transcription and translation at low temperatures. P. irgensii CspB bound to oligo(dT)-cellulose resins, suggesting single-stranded nucleic acid-binding activity. The unprecedented level of freeze-tolerance conferred by P. irgensii CspB suggests a crucial role for this protein in survival in polar environments.

Characteristics of Hospitalized Children with 2009 Pandemic Influenza A (H1N1): A Multicenter Study in Korea

The majority of Korean patients with pandemic influenza A (H1N1) during the 2009 epidemic were under 20 yr of age. The limited data on the clinical characteristics of these children led us to conduct a case note-based investigation of children admitted to 6 university hospitals with 2009 H1N1 influenza. A total of 804 children was enrolled. The median age was 5 yr; 63.8% were males; and 22.4% had at least one chronic underlying disease. Ninety-five of the patients (11.8%) were critically ill and they suffered more from shortness of breath, dyspnea and lymphopenia than the other patients. Among all the patients, 98.8% were treated with antivirals and 73% received treatment within 48 hr of illness onset. All the enrolled patients are alive and appear to have had good outcomes, probably due to the early intervention and antiviral treatment. This study deals with hospitalized children whose diagnoses of influenza A (H1N1) were confirmed, and therefore provides important new information about the clinical patterns of children with influenza A (H1N1) in Korea.

An Infant with Vertical Transmission of Human Immunodeficiency Virus Infection Detected Due to Failure to Thrive

Five to fifteen percent of patients affected by human immunodeficiency virus(HIV) are children in developing countries. In Korea, most of HIV infections in children have been transfusion-related, and cases of vertical transmission have been very rare so far and are usually suspected due to a maternal positive history. We experienced a case of vertical transmission of HIV in a 19 month- old girl, incidentally diagnosed in the process of work-up for failure to thrive without suspicion from maternal HIV history. With the increasing number of adult HIV patients in Korea, HIV in fection should be included in the differential diagnosis of children with symptoms compatible with HIV infection even when parental HIV history is not suggestive.

Viral Etiology of Community-acquired Pneumonia in Korean Adults / 감염

PURPOSES: To investigate the viral etiology of community-acquired pneumonia in Korean adults, we have detected respiratory viruses (Respiatory syncytial virus, adenovirus, influenza virus and parainfluenza virus) in the way of prospective, multi-center study. METHODS: From July 1997 to April 2000, nasal aspirates or sputum were obtained from adults patients with community pneumonia admitted to the participating hospitals and transferred immediately to the central laboratory in the Seoul National University Children's Hospital. The specimens were divided into three parts. One part was used for indirect immunofluorescent test for respiratory viruses, the other part for the culture of RSV and adenovirus in HEp-2 cell monolayer. Another part was used for the culture of influenza virus and parainfluenza virus in MDCK or LLC- MK2 cell monolayers. RESULTS: Of 317 samples, 32 (10.1%) specimens were positive for viral isolation by indirect IF staining or culture, including one dual-infected specimen (adenovirus and parainfluenza virus). Influenza virus was most commonly detected (16 specimens). Parainfluenza virus, adenovirus and RSV were detected in 10, 4 and 3 patients, respectively. All isolated influenza viruses were type A (H3N2 in 9 patients, H1N1 in 2 and unspecified in 5), and 8 out of 10 parainfluenza virus isolates were type 3. CONCLUSION: Similar to previous foreign reports, a significant portion of community-acquired pneumonia in Korean adult is caused by respiratory viruses. Our data empathized the need of referral system for viral diagnosis and of nationwide investigation on respiratory virus infections.

Induction Chemotherapy with N(4)-behenoyl-1-beta-D-arabinofuranosylcytosine, Idarubicin and 6-Thioguanine in Childhood Acute Myelogenous Leukemia / 대한소아혈액종양학회지

PURPOSE: Retrospective study was performed to evaluate the survivals, remission rate and complications of induction chemotherapy using N(4)-behenoyl-1-beta-D-arabinofuranosylcytosine (BH-AC), idarubicin and 6-thioguanine (6-TG) in newly diagnosed childhood acute myelogenous leukemia. METHODS: From July 1994 to March 2000, 40 children (male 30, female 10) were enrolled in the study. From day 0 to 6 of induction, BH-AC 300 mg/m(2)/day was administered intravenously over 3 hours and from day 7 to 9, dosage was adjusted according to residual leukemic blasts in day 7 bone marrow aspirates. Idarubicin 10 mg/m(2)/day was administered intravenously over 15 minutes from day 0 to 2 and 6-TG 100 mg/m(2)/ day orally divided in two from day 0 to 6. Median age at diagnosis was 4.4 years (1 month~14.9 years) with a distribution according to the FAB classification of 1 M1, 10 M2, 13 M4, 5 M4E, 7 M5a, 3 M6 and 1 M7. RESULTS: Complete remission (CR) rate was 82.5% (33/40) with one cycle of induction chemotherapy and 90.0% (36/40) with additional cycle (BH-AC and idarubicin). One patient achieved partial remission with one cycle and was lost to follow-up, and 3 died of septic shock with disseminated intravascular coagulopathy during induction. Median time to CR from diagnosis was 28 days (25~68) and recovery from neutropenia (ANC> 1,000/muL) was achieved on median day 24 (21~44). All 40 patients had a fever during neutropenic period. Toxicities such as diarrhea, mucositis, nausea and vomiting were observed over half of the patients but tolerable and transient. Five-year overall, relapse- free and event-free survivals were 54.0%, 51.1% and 46.7%, respectively. CONCLUSION: These data show that this regimen is superior to others with high remission rate and well tolerated.

Etiologic Agents and Clinical Features of Acute Pyogenic Osteoarthritis in Children

PURPOSE: Though acute pyogenic infections of musculoskeletal system are infrequent in children, delayed diagnosis or inadequate management may cause serious chronic sequelae. We analysed 40 cases of children who were affected by acute septic osteomyelitis and/or septic arthritis to find etiologic agents and to establish proper initial antimicrobial therapy. METHODS: Medical records of 40 cases of microbiologically confirmed acute pyogenic osteomyelitis and/or septic arthritis diagnosed at the Seoul National University Children's Hospital from January 1985 to September 1998 were reviewed. RESULTS: There were 12 cases of acute osteomyelitis, 28 of acute septic arthritis, and 4 of concurrent cases of two diseases. Of 12 cases of acute pyogenic osteomyelitis, there were 7 boys and 5 girls whose average age was 75.4 months. Calcaneus was infected in 4 cases and it was the most common site. Ten cases (83.3%) of them were attributable to Staphylococcus aureus, 1 to Streptococcus viridans and 1 to Pseudomonas aeruginosa. Among the 28 cases of acute septic arthritis, male to female ratio was 16 : 12. The hip joint was the most frequent site involved in 13 cases (46.3%), followed by the ankle joint, which was involved in 6 cases (21.4%). The majority of the children were infected by S. aureus (20 cases, 71.4%). Two cases were infected by S. viridans or Salmonella (group D) species, and 1 by Haemophilus influenzae. CONCLUSION: S. aureus was the most common pathogen of acute pyogenic osteoarthritis, and H. influenzae was an infrequent cause of septic arthritis. Regarding initial empirical anibiotic therapy, anti-staphylococcal agent should be included.

Infective Endocarditis in Children : Review of 35 Cases over 11 Years (1987-1997)

PURPOSE: Infective endocarditis (IE) is a serious complication in children with structural heart disease. We reviewed 35 cases of IE to identify the recent changes in the pattern of preexisting heart diseases, the spectrum of causative organisms and prognosis. METHODS: The clinical records of children diagnosed as IE at the Seoul National University Children's Hospital from January 1987 through December 1997, were reviewed retrospectively. Duke criteria was used for diagnosis. Cases were categorized into primary group(PG) IE in an unoperated heart and post operative group(POG), and the latter further into early POG(within 2 months after operation) and late POG. RESULTS: There were 35 cases of IE developed in 34 patients; 18 cases in the PG, 6 cases in the early POG, and 11 cases in the late POG. Male to female ratio was 16 : 19. Mean age of POG, especially early POG was less than that of PG (early POG : late POG : PG=1.65 years : 6.5 years : 8.34 years, P=0.0267). Preexisting heart diseases were identified in 30 cases; rheumatic heart disease 1 case and congenital heart disease (CHD) 29 cases. Causative organisms were identified in 80%; viridans streptococci, 10 cases (33.3%); pneumococci, 2 cases; Group-D streptococci, 3 cases; staphylococci, 8 cases; Gram (-) organisms, 5 cases and Candida albicans, 2 cases. Vegetation was detected in 88.9% of PG and 64.7% of POG. The most common indication for surgery was uncontrolled infection, which were required in 9 cases. The overall mortality rate was 12.1%. Mortality in POG was higher than that of PG (23.5% versus 0%, P=0.033). CONCLUSION: The discrepancy of mean age among patient groups and the high proportion of patients belonging to POG, were consistent with the increase in the number of newly risky population that survived after cardiac surgery. A more aggressive consideration for operative management may improve the treatment results.