Showing papers by "Joon Sup Yeom published in 2008"

Magnetic separation: a highly effective method for synchronization of cultured erythrocytic Plasmodium falciparum

Abstract: The magnetic method has been previously utilized to concentrate Plasmodium-infected erythrocytes without any significant influence on the viability of the parasite. We attempted, in this study, to concentrate and synchronize cultivated P. falciparum via the magnetic method. The results of this study showed that the magnetic method effectively synchronized and concentrated P. falciparum with finer demarcation capacity in the erythrocytic asexual cycle of the parasite than currently available synchronization methods. Concentration and synchronization by the magnetic method proved most effective when schizonts were dominant. Therefore, it proved necessary to enhance the synchronization efficiency of the magnetic method by first applying the method currently in use, which renders schizonts dominant. Our study also showed that the intrinsic life cycle of erythrocytic P. falciparum was slightly longer than 48 h observed in natural infection cases, and that the length of the intrinsic life cycles between various P. falciparum strains differed slightly.

Clonal Dissemination of Extended-Spectrum β-Lactamase (ESBL)-Producing Klebsiella pneumoniae Isolates in a Korean Hospital

Abstract: In this study, we investigated the molecular characteristics of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae isolates that were recovered from an outbreak in a Korean hospital. A new multilocus sequence typing (MLST) scheme for K. pneumoniae based on five housekeeping genes was developed and was evaluated for 43 ESBL-producing isolates from an outbreak as well as 38 surveillance isolates from Korea and also a reference strain. Overall, a total of 37 sequence types (STs) and six clonal complexes (CCs) were identified among the 82 K. pneumoniae isolates. The result of MLST analysis was concordant with that of pulsedfield gel electrophoresis. Most of the outbreak isolates belonged to a certain clone (ST2), and they produced SHV-1 and CTX-M14 enzymes, which was a different feature from that of the K. pneumoniae isolates from other Korean hospitals (ST20 and SHV-12). We also found a different distribution of CCs between ESBL-producing and -nonproducing K. pneumoniae isolates. The MLST method we developed in this study could provide unambiguous and well-resolved data for the epidemiologic study of K. pneumoniae. The outbreak isolates showed different molecular characteristics from the other K. pneumoniae isolates from other Korean hospitals.

Status of Vivax Malaria after Re-emergence in South Korea

Abstract: Submitted 31 July 2008, Accepted 11 August 2008 Correspondence : Jae-Won Park, M.D., Ph,D, Department of Microbiology, Graduate School of Medicine, Gachon University of Medicine and Science, 1198, Kuwol-1-dong, Namdong-gu, Incheon 405-760, Republic of Korea Tel : +82-32-460-2184, Fax : +82-32-421-5537 E-mail : seorak@dreamwiz.com 한 것으로 밝혀져 이제는 상기한 4종의 열원충 이외에 P. knowlesi도 인체 감염이 가능한 것으로 받아들여지고 있다 (1, 2). 전 세계적으로 20억 명 이상이 위험지역에서 살고 있고 매년 3-5억 명의 환자가 발생하며 단일질환으로 최다 인 연간 200만 명 이상이 말라리아로 인해 사망하고 있다 (3). 특히 사망자의 대부분이 열대지방에 위치한 저개발국 의 어린이들이기 때문에 말라리아는 이들 나라의 미래를 위협하는 대표적인 질환이다. 인체 감염 말라리아 중 전 세 계적으로 주종을 이루고 있는 것은 열대열 말라리아와 삼 일열 말라리아이다. 열대열 말라리아는 주로 열대지방에서 발생하고 있으며 말라리아로 인한 사망자의 대부분은 열대 열 말라리아에 의한 것이다. 삼일열 말라리아는 열대열 말 라리아에 비해 치명률은 떨어지나 열대, 아열대, 온대 지방 에 걸쳐 발생하므로 발생 지역 분포는 오히려 열대열 말라 리아보다도 훨씬 넓다. 온대 지방에 위치해 있는 국가에서 발생하는 말라리아는 대부분이 삼일열 말라리아이다. 지난 재출현 이후 국내 삼일열 말라리아 발생 현황

Naturally acquired IgM antibody response to the C-terminal region of the merozoite surface protein 1 of Plasmodium vivax in Korea: use for serodiagnosis of vivax malaria.

Abstract: The antibody levels against the C-terminal region of the merozoite surface protein 1 of Plasmodium vivax (PvMSP1c) were measured in 276 patients with P. vivax malaria (patient group), 320 malaria-naive healthy individuals (control group 1), and 70 malaria-naive individuals with various disorders (control group 2) using the immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA) and the direct sandwich ELISA. To evaluate the antibody response during relapse, 5 relapsed patients were tested using the IgM capture ELISA. The IgM antibodies were negative in 99.7% of control group 1 and in 100% of control group 2; they were positive in 90.6% of the patient group. The total antibody levels were positive in 88.4% of the patient group with the direct sandwich ELISA. The sera from the second malaria episode, i.e., relapsed patients, were 100% positive on the IgM capture ELISA. The results of this study suggest that the IgM capture ELISA may be a useful diagnostic method for P. vivax malaria for both primary infection and relapse.

Diagnosis of vivax malaria using an IgM capture ELISA is a sensitive method, even for low levels of parasitemia

Abstract: Although diagnosis of Plasmodium vivax malaria has been difficult when it is present at a low parasite density, it was recently revealed that an antibody assay was a good method of screening for malaria in blood banks. However, the use of this method for the diagnosis of malaria is limited due to the persistence of specific immunoglobulin (Ig) G. Therefore, we evaluated specific IgM antibody responses against the C-terminal region of the merozoite surface protein 1 of P. vivax (PvMSP1c) in sera obtained from patients with vivax malaria using various assays. The IgM capture enzyme-linked immunosorbent assay showed good sensitivity (97.7%; 308/315) and specificity (99.1%, 446/450). In addition, the results of this assay were not related to parasite density, and a high reactivity was observed when there was a low level of parasitemia. Furthermore, we found that patients with cases of malaria that had relapsed still had the IgM titers against PvMSP1c. Therefore, the use of IgM ELISA for the detection of specific IgM that was not involved in memorial immune activity could be an alternative tool for the diagnosis of malaria and blood screening, even in areas in which malaria is endemic.