• Parasites, Hosts and Diseases
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• 제51권2호
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• pp.203-206
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• 2013

After bathing at a hot spring resort, a 75-year-old man presented to the emergency department because of seizure-like attack with loss of conscious. This is the first case of primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri in Taiwan. PAM was diagnosed based on detection of actively motile trophozoites in cerebrospinal fluid using a wet-mount smear and the Liu's stain. The amoebae were further confirmed by PCR and gene sequencing. In spite of administering amphotericin B treatment, the patient died 25 days later.

• Parasites, Hosts and Diseases
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• 제48권2호
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• pp.157-160
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• 2010

We report here a human case probably mixed-infected with Clonorchis sinensis and Fasciola sp. who was diagnosed by computed tomography (Cn scan, serological findings, and/or fecal examination. The patient was a 43-year-old Korean female and was admitted to Kyung Hee University Hospital with the complaints of fever and abdominal pain. On admission, marked eosinophilia was noted in her peripheral blood. CT scan showed specific lesions for clonorchiasis and fascioliasis in the liver, along with lesions suggestive of amebic abscess. Micro-ELISA revealed positive results for the 2 helminthic infections. Eggs of C. sinensis and trophozoites of Entamoeba histo/ytica were observed in the stool. Treatment with praziquantel followed by metronidazole and tinidazole reduced abnormalities in the liver and eosinophilia. This is the first case report of a possible co-infection with 2 kinds of liver flukes in the Republic of Korea.

• Parasites, Hosts and Diseases
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• 제44권4호
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• pp.331-341
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• 2006

Actin binding proteins play key roles in cell structure and movement particularly as regulators of the assembly, stability and localization of actin filaments in the cytoplasm. In the present study, a cDNA clone encoding an actin bundling protein named as AhABP was isolated from Acanthamoeba healyi, a causative agent of granulomatous amebic encephalitis. This clone exhibited high similarity with genes of Physarum polycephalum and Dictyostelium discoideum, which encode actin bundling proteins. Domain search analysis revealed the presence of essential conserved regions, i.e., an active actin binding site and 2 putative calcium binding EF-hands. Transfected amoeba cells demonstrated that AhABP is primarily localized in phagocytic cups, peripheral edges, pseudopods, and in cortical cytoplasm where actins are most abundant. Moreover, AhABP after the deletion of essential regions formed ellipsoidal inclusions within transfected cells. High-speed co-sedimentation assays revealed that AhABP directly interacted with actin in the presence of up to $10{\mu}M$ of calcium. Under the electron microscope, thick parallel bundles were formed by full length AhABP, in contrast to the thin actin bundles formed by constructs with deletion sites. In the light of these results, we conclude that AhABP is a novel actin bundling protein that is importantly associated with actin filaments in the cytoplasm.

• Parasites, Hosts and Diseases
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• 제54권4호
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• pp.447-453
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• 2016

Acanthamoeba, a free-living amoeba, is widely distributed in the environment, water sources, soil, dust, and air. It can cause keratitis in contact lens wearers with poor hygiene and also fatal granulomatous amebic encephalitis (GAE) in immunocompromised hosts. The aim of this study was to gain some insights into the distribution and genotypes of the potentially pathogenic species of Acanthamoeba present in water sources in north of Iran. Total 43 Acanthamoeba species were isolated from 77 water samples taken from different water sources within the Mazandaran province in Northern Iran (Sari city and suburbs). Isolates were identified based on cyst and trophozoite morphological characteristics as well genetics. PCR fragments corresponding to the small-subunit 18S rRNA gene were sequenced for 20 of 43 positive isolates. The results revealed that 83.3% of sequenced isolates belonged to the T4 genotype and the rest belonged to the T2 genotype. Our results indicated that Acanthamoeba is widely distributed in Sari city. As the incidence in Iran of amoebic keratitis has increased in recent years, the exact estimation of the prevalence of this amoeba and its predominant genotype may play a crucial role in prevention of the disease. Sari city has several rivers, seashores, and natural recreational amenities, which attract visitors during the year. This is the first report of Acanthamoeba genotypes from water sources in Sari city, Mazandaran province of Iran, and the results suggest that more attention is needed to protect the visiting population and immunocompromised individuals.

• Parasites, Hosts and Diseases
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• 제49권2호
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• pp.177-180
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• 2011

Entamoeba histolytica is an enteric tissue-invading protozoan parasite that can cause amebic colitis and liver abscess in humans. E. histolytica has the capability to kill colon epithelial cells in vitro; however, information regarding the role of calpain in colon cell death induced by ameba is limited. In this study, we investigated whether calpains are involved in the E. histolytica-induced cell death of HT-29 colonic epithelial cells. When HT-29 cells were co-incubated with E. histolytica, the propidium iodide stained dead cells markedly increased compared to that in HT-29 cells incubated with medium alone. This pro-death effect induced by ameba was effectively blocked by pretreatment of HT-29 cells with the calpain inhibitor, calpeptin. Moreover, knockdown of m- and ${\mu}$-calpain by siRNA significantly reduced E. histolytica-induced HT-29 cell death. These results suggest that m- and ${\mu}$-calpain may be involved in colon epithelial cell death induced by E. histolytica.

• 한국동물위생학회지
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• 제42권4호
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• pp.169-175
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• 2019

Naegleria fowleri, a pathogenic free-living amoeba, leads to a fatal infection known as primary amebic meningoencephalitis (PAM) in human and animals. PAM is an acute, fulminant, necrotizing, and hemorrhagic disease that leads to death in approximately seven days. In this study, we investigate the cytotoxicity of target cells and the secreted molecules of N. fowleri under the non-contact condition. The target cell (U87MG cell) treated with N. fowleri lysates showed no morphological changes and no cytotoxicity. By contrast, the U87MG cells co-cultured with N. fowleri trophozoites under the non-contact condition induced morphological changes and reduction in number. When U87MG cells were co-cultured with N. fowleri trophozoites under the non-contact condition for 30 min, 2 hr, and 4 hr, the levels of cytotoxicity of target cells were 32.3, 35.5, and 37.8%, respectively. Particularly, when the ratio of amoeba to target cells is 10 to 1, the level of cytotoxicity of target cells was 49.7% at 30 min. To show the proteins secreted from N. fowleri under the non-contact condition, we carried out 2D electrophoresis and observed 6 major proteins. Finally, these results suggest that the molecules released from N. fowleri under the non-contact condition induce the cell death and this process is an important step in pathogenesis of N. fowleri.

• Parasites, Hosts and Diseases
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• 제52권4호
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• pp.355-365
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• 2014

The enteric protozoan parasite Entamoeba histolytica is the causative agent of human amebiasis. During infection, adherence of E. histolytica through Gal/GalNAc lectin on the surface of the amoeba can induce caspase-3-dependent or -independent host cell death. Phosphorylinositol 3-kinase (PI3K) and protein kinase C (PKC) in E. histolytica play an important function in the adhesion, killing, or phagocytosis of target cells. In this study, we examined the role of amoebic PI3K and PKC in amoeba-induced apoptotic cell death in Jurkat T cells. When Jurkat T cells were incubated with E. histolytica trophozoites, phosphatidylserine (PS) externalization and DNA fragmentation in Jurkat cells were markedly increased compared to those of cells incubated with medium alone. However, when amoebae were pretreated with a PI3K inhibitor, wortmannin before being incubated with E. histolytica, E. histolytica-induced PS externalization and DNA fragmentation in Jurkat cells were significantly reduced compared to results for amoebae pretreated with DMSO. In addition, pretreatment of amoebae with a PKC inhibitor, staurosporine strongly inhibited Jurkat T cell death. However, E. histolytica-induced cleavage of caspase-3, -6, and -7 were not inhibited by pretreatment of amoebae with wortmannin or staurosporin. In addition, we found that amoebic PI3K and PKC have an important role on amoeba adhesion to host compartment. These results suggest that amebic PI3K and PKC activation may play an important role in caspase-independent cell death in Entamoeba-induced apoptosis.

• Parasites, Hosts and Diseases
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• 제46권4호
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• pp.217-221
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• 2008

Free-living Naegleria fowleri leads to a fatal infection known as primary amebic meningoencephalitis in humans. Previously, the target cell death could be induced by phagocytic activity of N. fowleri as a contact-dependent mechanism. However, in this study we investigated the target cell death under a non-contact system using a tissue-culture insert. The human microglial cells, U87MG cells, co-cultured with N. fowleri trophozoites for 30 min in a non-contact system showed morphological changes such as the cell membrane destruction and a reduction in the number. By fluorescence-activated cell sorter (FACS) analysis, U87MG cells co-cultured with N. fowleri trophozoites in a non-contact system showed a significant increase of apoptotic cells (16%) in comparison with that of the control or N. fowleri lysate. When U87MG cells were co-cultured with N. fowleri trophozoites in a non-contact system for 30 min, 2 hr, and 4 hr, the cytotoxicity of amebae against target cells was 40.5, 44.2, and 45.6%, respectively. By contrast, the cytotoxicity of non-pathogenic N. gruberi trophozoites was 10.2, 12.4, and 13.2%, respectively. These results suggest that the molecules released from N. fowleri in a contact-independent manner as well as phagocytosis in a contact-dependent manner may induce the host cell death.

• Parasites, Hosts and Diseases
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• 제26권3호
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• pp.169-174
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• 1988

Naegleria fowleri로 면역된 마우스 비장세포를 이입(이입)함으로써 원발성 아메바성 수막 뇌염의 발생을 방어할 수 있는지 즉 방어면역을 피동적으로 전달할 수 있는지를 관찰하였다. 무균 배양한 N. fowleri, ITMAP 359 영 양형 7×l04개를 생후 6주된 ICR 마우스에 감염시켰다. 살아있는 N. fowleri 영양형 106개씩을 1주일 간격으로 3회 복강내로 주입시켜 면역시켰다. 면역시킨 마우스의 비장을 적출하여 107개의 비장세포가 함유된 부유액을 마우스 복강내로 주입시키고 3일 후 N, fowleri를 감염시켰다. 비장세포에 Con. A와 lipopolysaccharide(LPS)를 처리한 후 배자발생 정도를 methyl-[3H]-thymidine을 사용하여 측정하였다. N. fowleri를 감염시킨 마우스의 사망률을 보면 정상 비장세포를 주입시킨 실험대조군에서 84%, 면역 비장세포를 주입시킨 실험군에서 72%로서, 정상 대조군에서의 사망률 100%에 비해 낮음을 알 수 있었다. 면역된 비장세포를 주입시킨 실험군에서 LPS를 처리한 비장세포의 배자발생정도는 감염 7일 후 실험대조군이나 정상대조군에 비해 증가되어 있었고, Con. A처리에 의한 배자발생 정도도 감염 7일 후 증가되어 있음을 관찰할 수 있었다. 혈청내 항체가는 감염 12일 후 정상 대조군에 비해 실험군과 실험대조군에서 높았다.

• Journal of Yeungnam Medical Science
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• 제2권1호
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• pp.87-93
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• 1985

1983년 5월부터 1985년 11월까지 영남대학교 의과대학 부속병원에서 복부농양을 의심하여 초음파검사를 시행후 확진된 48명의 환자에서 초음파소견을 분석하여 다음과 같은 결과를 얻었다. 1) 농양의 위치는 복강내 농양이 30예, 내장 농양이 13예, 후북막강농양이 5예였다. 2) 원인별로는 복강내 농양의 25예는 충수돌기염에 의하였고. 5예는 수술후 합병증으로 생겼다. 후복막강농양 5예는 전부 요근농양으로, 결핵성 및 화농성이 각각 2예, 후복막강에 위치한 충수돌기 염증이 1예였다. 내장농양은 12예가 간농양으로 이 중 9예는 화농성, 3예는 아메바성이었고 췌장염에 의한 췌장미부농양이 l예였다. 3) 형태는 총 48예중 26예(54%)에서 구형 또는 난원형이었으며, 특히 내장농양이 복강내 농양에 비해 구형 또는 난원형이 많았다. 4) 병변의 크기는 26예(54%)에서 5~10cm사이였으며, 내부echo는 33예(69%)에서 낭포성이었다.