Publications by authors named "Bijay Kumar Jha"

20 Publications

  • Page 1 of 1

Cyclophilin 19 secreted in the host cell cytosol by Trypanosoma cruzi promotes ROS production required for parasite growth.

Cell Microbiol 2020 Nov 22:e13295. Epub 2020 Nov 22.

Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.

Infection by Trypanosoma cruzi, the protozoan parasite that causes Chagas disease, depends on reactive oxygen species (ROS), which has been described to induce parasite proliferation in mammalian host cells. It is unknown how the parasite manages to increase host ROS levels. Here, we found that intracellular T. cruzi forms release in the host cytosol its major cyclophilin of 19 kDa (TcCyp19). Parasites depleted of TcCyp19 by using CRISPR/Cas9 gene replacement proliferate inefficiently and fail to increase ROS, compared to wild type parasites or parasites with restored TcCyp19 gene expression. Expression of TcCyp19 in L6 rat myoblast increased ROS levels and restored the proliferation of TcCyp19 depleted parasites. These events could also be inhibited by cyclosporin A, (a cyclophilin inhibitor), and by polyethylene glycol-linked to antioxidant enzymes. TcCyp19 was found more concentrated in the membrane leading edges of the host cells in regions that also accumulate phosphorylated p47 , as observed to the endogenous cyclophilin A, suggesting some mechanisms involved with the translocation process of the regulatory subunit p47 in the activation of the NADPH oxidase enzymatic complex. We concluded that cyclophilin released in the host cell cytosol by T. cruzi mediates the increase of ROS, required to boost parasite proliferation in mammalian hosts.
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http://dx.doi.org/10.1111/cmi.13295DOI Listing
November 2020

The role of vascular endothelium and exosomes in human protozoan parasitic diseases.

Vessel Plus 2020 27;4. Epub 2020 Sep 27.

Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, The Ohio State University Medical Center, Columbus, OH 43201, USA.

The vascular endothelium is a vital component in maintaining the structure and function of blood vessels. The endothelial cells (ECs) mediate vital regulatory functions such as the proliferation of cells, permeability of various tissue membranes, and exchange of gases, thrombolysis, blood flow, and homeostasis. The vascular endothelium also regulates inflammation and immune cell trafficking, and ECs serve as a replicative niche for many bacterial, viral, and protozoan infectious diseases. Endothelial dysfunction can lead to vasodilation and pro-inflammation, which are the hallmarks of many severe diseases. Exosomes are nanoscale membrane-bound vesicles that emerge from cells and serve as important extracellular components, which facilitate communication between cells and maintain homeostasis during normal and pathophysiological states. Exosomes are also involved in gene transfer, inflammation and antigen presentation, and mediation of the immune response during pathogenic states. Protozoa are a diverse group of unicellular organisms that cause many infectious diseases in humans. In this regard, it is becoming increasingly evident that many protozoan parasites (such as , , , and ) utilize exosomes for the transfer of their virulence factors and effector molecules into the host cells, which manipulate the host gene expression, immune responses, and other biological activities to establish and modulate infection. In this review, we discuss the role of the vascular endothelium and exosomes in and their contribution to pathogenesis in malaria, African sleeping sickness, Chagas disease, and leishmaniasis and toxoplasmosis with an emphasis on their actions on the innate and adaptive immune mechanisms of resistance.
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http://dx.doi.org/10.20517/2574-1209.2020.27DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7575144PMC
September 2020

Effect of a scaled-up neonatal resuscitation quality improvement package on intrapartum-related mortality in Nepal: A stepped-wedge cluster randomized controlled trial.

PLoS Med 2019 09 9;16(9):e1002900. Epub 2019 Sep 9.

Department of Women's and Children's Health; Uppsala University, Uppsala, Sweden.

Background: Improving quality of intrapartum care will reduce intrapartum stillbirth and neonatal mortality, especially in resource-poor settings. Basic neonatal resuscitation can reduce intrapartum stillbirth and early neonatal mortality, if delivered in a high-quality health system, but there is a dearth of evidence on how to scale up such evidence-based interventions. We evaluated the scaling up of a quality improvement (QI) package for neonatal resuscitation on intrapartum-related mortality (intrapartum stillbirth and first day mortality) at hospitals in Nepal.

Methods And Findings: We conducted a stepped-wedge cluster randomized controlled trial in 12 hospitals over a period of 18 months from April 14, 2017, to October 17, 2018. The hospitals were assigned to one of four wedges through random allocation. The QI package was implemented in a stepped-wedge manner with a delay of three months for each step. The QI package included improving hospital leadership on intrapartum care, building health workers' competency on neonatal resuscitation, and continuous facilitated QI processes in clinical units. An independent data collection system was set up at each hospital to gather data on mortality through patient case note review and demographic characteristics of women using semi-structured exit interviews. The generalized linear mixed model (GLMM) and multivariate logistic regression were used for analyses. During this study period, a total of 89,014 women-infant pairs were enrolled. The mean age of the mother in the study period was 24.0 ± 4.3 years, with 54.9% from disadvantaged ethnic groups and 4.0% of them illiterate. Of the total birth cohort, 54.4% were boys, 16.7% had gestational age less than 37 weeks, and 17.1% had birth weight less than 2,500 grams. The incidence of intrapartum-related mortality was 11.0 per 1,000 births during the control period and 8.0 per 1,000 births during the intervention period (adjusted odds ratio [aOR], 0.79; 95% CI, 0.69-0.92; p = 0.002; intra-cluster correlation coefficient [ICC], 0.0286). The incidence of early neonatal mortality was 12.7 per 1,000 live births during the control period and 10.1 per 1,000 live births during the intervention period (aOR, 0.89; 95% CI, 0.78-1.02; p = 0.09; ICC, 0.1538). The use of bag-and-mask ventilation for babies with low Apgar score (<7 at 1 minute) increased from 3.2% in the control period to 4.0% in the intervention period (aOR, 1.52; 95% CI, 1.32-1.77, p = 0.003). There were two major limitations to the study; although a large sample of women-infant pairs were enrolled in the study, the clustering reduced the power of the study. Secondly, the study was not sufficiently powered to detect reduction in early neonatal mortality with the number of clusters provided.

Conclusion: These results suggest scaled-up implementation of a QI package for neonatal resuscitation can reduce intrapartum-related mortality and improve clinical care. The QI intervention package is likely to be effective in similar settings. More implementation research is required to assess the sustainability of QI interventions and quality of care.

Trial Registration: ISRCTN30829654.
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http://dx.doi.org/10.1371/journal.pmed.1002900DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6733443PMC
September 2019

Scaling Up Safer Birth Bundle Through Quality Improvement in Nepal (SUSTAIN)-a stepped wedge cluster randomized controlled trial in public hospitals.

Implement Sci 2019 06 19;14(1):65. Epub 2019 Jun 19.

Department of Women's and Children's Health, Uppsala University, Dag Hammarskjölds väg 14B, Uppsala, Sweden.

Background: Each year, 2.2 million intrapartum-related deaths (intrapartum stillbirths and first day neonatal deaths) occur worldwide with 99% of them taking place in low- and middle-income countries. Despite the accelerated increase in the proportion of deliveries taking place in health facilities in these settings, the stillborn and neonatal mortality rates have not reduced proportionately. Poor quality of care in health facilities is attributed to two-thirds of these deaths. Improving quality of care during the intrapartum period needs investments in evidence-based interventions. We aim to evaluate the quality improvement package-Scaling Up Safer Bundle Through Quality Improvement in Nepal (SUSTAIN)-on intrapartum care and intrapartum-related mortality in public hospitals of Nepal.

Methods: We will conduct a stepped wedge cluster randomized controlled trial in eight public hospitals with each having least 3000 deliveries a year. Each hospital will represent a cluster with an intervention transition period of 2 months in each. With a level of significance of 95%, the statistical power of 90% and an intra-cluster correlation of 0.00015, a study period of 19 months should detect at least a 15% change in intrapartum-related mortality. Quality improvement training, mentoring, systematic feedback, and a continuous improvement cycle will be instituted based on bottleneck analyses in each hospital. All concerned health workers will be trained on standard basic neonatal resuscitation and essential newborn care. Portable fetal heart monitors (Moyo®) and neonatal heart rate monitors (Neobeat®) will be introduced in the hospitals to identify fetal distress during labor and to improve neonatal resuscitation. Independent research teams will collect data in each hospital on intervention inputs, processes, and outcomes by reviewing records and carrying out observations and interviews. The dose-response effect will be evaluated through process evaluations.

Discussion: With the global momentum to improve quality of intrapartum care, better understanding of QI package within a health facility context is important. The proposed package is based on experiences from a similar previous scale-up trial carried out in Nepal. The proposed evaluation will provide evidence on QI package and technology for implementation and scale up in similar settings.

Trial Registration Number: ISRCTN16741720 . Registered on 2 March 2019.
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http://dx.doi.org/10.1186/s13012-019-0917-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6582583PMC
June 2019

Host-Directed Drug Therapies for Neglected Tropical Diseases Caused by Protozoan Parasites.

Front Microbiol 2018 30;9:2655. Epub 2018 Nov 30.

Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States.

The neglected tropical diseases (NTDs) caused by protozoan parasites are responsible for significant morbidity and mortality worldwide. Current treatments using anti-parasitic drugs are toxic and prolonged with poor patient compliance. In addition, emergence of drug-resistant parasites is increasing worldwide. Hence, there is a need for safer and better therapeutics for these infections. Host-directed therapy using drugs that target host pathways required for pathogen survival or its clearance is a promising approach for treating infections. This review will give a summary of the current status and advances of host-targeted therapies for treating NTDs caused by protozoa.
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http://dx.doi.org/10.3389/fmicb.2018.02655DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6284052PMC
November 2018

Oral hygiene practices and their socio-demographic correlates among Nepalese adult: evidence from non communicable diseases risk factors STEPS survey Nepal 2013.

BMC Oral Health 2016 Sep 29;16(1):105. Epub 2016 Sep 29.

Nepal Health Research Council, Ramshahpath, Kathmandu, 44600, Nepal.

Background: Oral diseases remain a significant public health problem in Nepal, as do oral health behaviours. Socio-demographic factors play a crucial role in driving oral hygiene practices. This study aims to identify oral hygiene practices and associated socio-demographic factors in Nepalese population.

Methods: This descriptive, cross-sectional study recruited 4200 adults (15-69 years) through multistage cluster sampling. Data obtained from the WHO NCD STEPS instrument version 2.2 were analysed in STATA 13.0 using complex sample weighted analysis.

Results: Prevalence of cleaning teeth at least once a day was 94.9 % (95 % CI: 93.7-95.9), while that of cleaning teeth at least twice a day was 9.9 % (95 % CI: 8.2-11.9). Use of fluoridated toothpaste was seen among 71.4 % (95 % CI: 67.9-74.7) respondents. A 3.9 % (95 % CI: 3.1-5.0) made a dental visit in the last 6 months. The 45-69 years age group had lesser odds of cleaning teeth at least once a day (AOR: 0.4; 95 % CI: 0.2-0.8), in comparison to 15-29 years age group. Women had greater odds of cleaning teeth at least twice a day (AOR: 1.7; 95 % CI: 1.1-2.4) and having visited a dentist in the last 6 months (AOR: 2.2; 95 % CI: 1.2-3.8) compared to men. With reference to rural residents, urban population had higher odds of using fluoridated toothpaste (AOR: 2.3; 95 % CI: 1.4-3.4) and making a dental visit within the last 6 months (AOR: 1.9; 95 % CI:1.1-3.6). Inhabitants of the Terai had five-fold (AOR: 4.9; 95 % CI: 3.1-7.8) greater odds of cleaning teeth once per day than did hill residents. Those with higher education had greater odds than non-formal education holders of cleaning teeth at least once a day (AOR: 9.0; 95 % CI: 2.9-27.7), cleaning teeth at least twice a day (AOR: 5.6; 95 % CI: 2.9-10.6), using fluoridated toothpaste (AOR: 13.9; 95 % CI: 8.4-23.1), and having visited a dentist in the last 6 months (AOR: 2.8; 95 % CI: 1.4-5.4).

Conclusions: Cleaning teeth at least once a day is widely prevalent in Nepal and a substantial number of population use fluoridated toothpaste. However, cleaning teeth twice a day and visiting a dentist is less common. Being women, Terai residents, urban residents, and educated were significantly associated with oral hygiene practices assessed in this study.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5041565PMC
http://dx.doi.org/10.1186/s12903-016-0294-9DOI Listing
September 2016

Juglone induces cell death of Acanthamoeba through increased production of reactive oxygen species.

Exp Parasitol 2015 Dec 7;159:100-6. Epub 2015 Sep 7.

Department of Microbiology, Keimyung University School of Medicine, Daegu, Republic of Korea. Electronic address:

Juglone (5-hydroxy-1,4-naphthoquinone) is a major chemical constituent of Juglans mandshruica Maxim. Recent studies have demonstrated that juglone exhibits anti-cancer, anti-bacterial, anti-viral, and anti-parasitic properties. However, its effect against Acanthamoeba has not been defined yet. The aim of this study was to investigate the effect of juglone on Acanthamoeba. We demonstrate that juglone significantly inhibits the growth of Acanthamoeba castellanii at 3-5 μM concentrations. Juglone increased the production of reactive oxygen species (ROS) and caused cell death of A. castellanii. Inhibition of ROS by antioxidant N-acetyl-l-cysteine (NAC) restored the cell viability. Furthermore, our results show that juglone increased the uptake of mitochondrial specific dye. Collectively, these results indicate that ROS played a significant role in the juglone-induced cell death of Acanthamoeba.
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http://dx.doi.org/10.1016/j.exppara.2015.09.005DOI Listing
December 2015

Tigecycline inhibits proliferation of Acanthamoeba castellanii.

Parasitol Res 2015 Mar 7;114(3):1189-95. Epub 2015 Jan 7.

Department of Microbiology, Keimyung University School of Medicine, 1095 Dalgubeol-daero, Dalseo-gu, Daegu, 704-701, Republic of Korea.

Acanthamoeba is an opportunistic protozoan parasite responsible for different diseases in humans, such as granulomatous amoebic encephalitis and amoebic keratitis. Tigecycline, a third-generation tetracycline antibiotic, has potential activity to treat most of the antibiotic resistant bacterial infections. The effects of tigecycline in eukaryotic cells as well as parasites are less well studied. In the present study, we tested the effects of tigecycline on trophozoites of Acanthamoeba castellanii. The inhibitory effect of tigecycline on Acanthamoeba was determined by resazurin reduction and trypan blue exclusion assays. We found that tigecycline significantly inhibited the growth of Acanthamoeba (46.4 % inhibition at the concentration of 100 μM) without affecting cell viability and induction of encystation, whereas other tetracycline groups of antibiotics such as tetracycline and doxycycline showed no inhibitory effects. Furthermore, tigecycline decreased cellular adenosine triphosphate (ATP) level by 26 % than the control and increased mitochondrial mass, suggesting mitochondrial dysfunction in tigecycline-treated cells. These findings suggest that mitochondrial dysfunction with decreased ATP production might play an important mechanism of tigecycline in suppression of Acanthamoeba proliferation.
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http://dx.doi.org/10.1007/s00436-014-4302-1DOI Listing
March 2015

Chloroquine has a cytotoxic effect on Acanthamoeba encystation through modulation of autophagy.

Antimicrob Agents Chemother 2014 Oct 11;58(10):6235-41. Epub 2014 Aug 11.

Department of Microbiology, Keimyung University School of Medicine, Daegu, Republic of Korea

Encystation of Acanthamoeba castellanii is associated with resistance to chemotherapeutic agents. Blocking the encystation process could potentiate the efficacy of chemotherapeutic agents and biocides. During encystation, autophagy is highly stimulated and required for proper encystation of Acanthamoeba. In this study, the cytotoxic effect of chloroquine, a well-known autophagy-inhibitory drug, was tested in A. castellanii. Chloroquine was able to selectively reduce cell survival during the encystation of A. castellanii. However, A. castellanii trophozoites and mature cysts were resistant to chloroquine. Chloroquine treatment led to an increase in the number and size of lysosomes in encysting cells. Moreover, chloroquine inhibited the degradation of long-lived proteins in the encysting cells. Decreased autophagic flux, indicated by an increased number of lysosomes and decreased degradation of long-lived proteins, may be the mechanism by which cell death is induced by chloroquine in encysting Acanthamoeba. These results suggest a potential novel therapeutic application of chloroquine as an anti-Acanthamoeba drug. Our findings also suggest that targeting autophagy could be a therapeutic strategy against Acanthamoeba infection.
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http://dx.doi.org/10.1128/AAC.03164-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4187977PMC
October 2014

Translational suppression of HIF-1α by miconazole through the mTOR signaling pathway.

Cell Oncol (Dordr) 2014 Aug 29;37(4):269-79. Epub 2014 Jul 29.

Department of Microbiology, Keimyung University School of Medicine, 1095 Dalgubeol-daero, Dalseo-gu, Daegu, 704-701, Republic of Korea.

Background: Miconazole is an imidazole antifungal agent that has amply been used in the treatment of superficial mycosis. Preliminary data indicate that miconazole may also induce anticancer effects. As yet, however, little is known about the therapeutic efficacy of miconazole on cancer and the putative mechanism(s) involved. Here, we show that miconazole suppresses hypoxia inducible factor-1α (HIF-1α) protein translation in different cancer-derived cells.

Methods: The effect of miconazole on HIF-1α expression was examined by Western blotting and reverse transcriptase polymerase chain reaction assays in human U87MG and MCF-7 glioma and breast cancer-derived cell lines, respectively. The transcriptional activity of the HIF-1 complex was confirmed using a luciferase assay. To assess whether angiogenic factors are increased under hypoxic conditions in these cells, vascular endothelial growth factor (VEGF) levels were measured by ELISA. Metabolic labeling was performed to examine HIF-1α protein translation and global protein synthesis. The role of the mammalian target of rapamycin (mTOR) signaling pathway was examined to determine translation regulation of HIF-1α after miconazole treatment.

Results: Miconazole was found to suppress HIF-1α protein expression through post-transcriptional regulation in U87MG and MCF-7 cells. The suppressive effect of HIF-1α protein synthesis was found to be due to inhibition of mTOR. Miconazole significantly inhibited the transcriptional activity of the HIF-1 complex and the expression of its target VEGF. Moreover, miconazole was found to suppress global protein synthesis by inducing phosphorylation of the translation initiation factor 2α (eIF2α).

Conclusion: Our data indicate that miconazole plays a role in translational suppression of HIF-1α. We suggest that miconazole may represent a novel therapeutic option for the treatment of cancer.
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http://dx.doi.org/10.1007/s13402-014-0182-8DOI Listing
August 2014

Identification of lysosomotropic compounds based on the distribution and size of lysosomes.

Biochem Biophys Res Commun 2014 Jul 27;450(1):189-94. Epub 2014 May 27.

Department of Microbiology, School of Medicine, Keimyung University, Daegu, Republic of Korea; Institute for Cancer Research, School of Medicine, Keimyung University, Daegu, Republic of Korea. Electronic address:

Lysosomal accumulation of drugs with their specific physicochemical properties is of key importance to drug distribution in the body. Several attempts have been made to treat various human diseases by employing the accumulation of lysosomal drugs, and many methods to identify lysosomal accumulation of drugs have been proposed. Among those, the use of high-content screening has increased tremendously because of improved efficiency and accuracy as well as the development of automatic image acquisition and analytical techniques. Conventional methods to identify lysosomal accumulation of drugs by evaluating changes in the lysosomal area are unable to maximize the advantages of phenotypic high-content screening. Lysosomal distribution and the size of lysosomes are affected by lysosomal accumulating drugs. Therefore, we present image acquisition conditions and analytical methods to utilize lysosomal distribution and size as parameters for identifying lysosomal accumulating drugs. These two parameters will help to improve the reliability of the screening methods for identifying lysosomal accumulation of drugs by maximizing usage of information from image-based screening.
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http://dx.doi.org/10.1016/j.bbrc.2014.05.091DOI Listing
July 2014

Minocycline inhibits angiogenesis in vitro through the translational suppression of HIF-1α.

Arch Biochem Biophys 2014 Mar 8;545:74-82. Epub 2014 Jan 8.

Department of Microbiology, Keimyung University School of Medicine, Daegu, Republic of Korea. Electronic address:

Minocycline was recently found to be effective against cancer. However, the precise molecular mechanisms of minocycline in cancer are poorly understood. Hypoxia-inducible factor-1 (HIF-1, a heterodimeric transcription factor composed of HIF-1α and β) activates the transcription of genes that are involved in angiogenesis in cancer. In this study, we found that minocycline significantly inhibits HIF-1α protein expression and suppresses HIF-1 transcriptional activity. The tube formation assay showed that minocycline has anti-angiogenic activity and suppresses hypoxia-induced vascular endothelial growth factor (VEGF) expression. The metabolic labeling assay showed that minocycline reduces HIF-1α protein translation and global protein synthesis. In addition, minocycline suppresses mTOR signaling and increases the phosphorylation of eIF2α, which is known to be related to the translational regulation of HIF-1α expression. These findings collectively indicate that minocycline is a potential inhibitor of HIF-1α and provide new insight into the discovery of drugs for cancer treatment.
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http://dx.doi.org/10.1016/j.abb.2013.12.023DOI Listing
March 2014

Loop-mediated isothermal amplification targeting 18S ribosomal DNA for rapid detection of Acanthamoeba.

Korean J Parasitol 2013 Jun 30;51(3):269-77. Epub 2013 Jun 30.

Department of Parasitology and Tropical Medicine, Kyungpook National University School of Medicine, Daegu 700-422, Korea.

Amoebic keratitis (AK) caused by Acanthamoeba is one of the most serious corneal infections. AK is frequently misdiagnosed initially as viral, bacterial, or fungal keratitis, thus ensuring treatment delays. Accordingly, the early detection of Acanthamoeba would contribute significantly to disease management and selection of an appropriate anti-amoebic therapy. Recently, the loop-mediated isothermal amplification (LAMP) method has been applied to the clinical diagnosis of a range of infectious diseases. Here, we describe a rapid and efficient LAMP-based method targeting Acanthamoeba 18S rDNA gene for the detection of Acanthamoeba using clinical ocular specimens in the diagnosis of AK. Acanthamoeba LAMP assays detected 11 different strains including all AK-associated species. The copy number detection limit for a positive signal was 10 DNA copies of 18S rDNA per reaction. No cross-reactivity with the DNA of fungi or other protozoa was observed. The sensitivity of LAMP assay was higher than those of Nelson primer PCR and JDP primer PCR. In the present study, LAMP assay based on directly heat-treated samples was found to be as efficient at detecting Acanthamoeba as DNA extracted using a commercial kit, whereas PCR was only effective when commercial kit-extracted DNA was used. This study showed that the devised Acanthamoeba LAMP assay could be used to diagnose AK in a simple, sensitive, and specific manner.
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http://dx.doi.org/10.3347/kjp.2013.51.3.269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3712100PMC
June 2013

Evaluation of the efficacy of chloroquine chemoprophylaxis for vivax malaria among Republic of Korea military personnel.

Parasitol Int 2013 Dec 12;62(6):494-6. Epub 2013 Jul 12.

Department of Medicine, Headquarters of Republic of Korea Army, Choongnam, Republic of Korea.

Chloroquine has been used massively for vivax malaria prophylaxis and treatment in the Republic of Korea (ROK) military personnel from 1997. Although prophylaxis is generally regarded as successful among ROK military, prophylaxis failure has been repeatedly reported. Before the prophylaxis program was started on July 4th 2011, which was completed on October 16th 2011, by the ROK military, more than 60% of malaria cases were attributed to new infection or long-latency relapse. During the prophylaxis program, the authors re-examined the efficiency of chloroquine chemoprophylaxis in ROK military during the last 6 months of 2011 by measuring compliance and whole blood chloroquine levels in 41 malaria patients immediately before instituting antimalarial therapy between July and December. Three patients (7.3%) showed good compliance, and had whole blood total chloroquine levels above the minimally inhibitory concentration (100 ng/mL). However, 28 (69.3%) of these 41 patients when admitted to hospital showed poor or no compliance with prophylaxis; 4 of the 28 (14.3%) were stationed outside the mass prophylaxis region, and 5 (17.9%) subjects were infected after the prophylaxis program had finished. These findings indicate that the current malaria control program should be carefully reconsidered, in terms of, individual instruction, current chemoprophylaxis program regimens, and schedules to improve the efficacy of prophylaxis in the ROK military.
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http://dx.doi.org/10.1016/j.parint.2013.07.002DOI Listing
December 2013

Cysteine protease inhibitor (AcStefin) is required for complete cyst formation of Acanthamoeba.

Eukaryot Cell 2013 Apr 8;12(4):567-74. Epub 2013 Feb 8.

Department of Parasitology and Tropical Medicine, Kyungpook National University School of Medicine, Daegu, South Korea.

The encystation of Acanthamoeba leads to the formation of resilient cysts from vegetative trophozoites. This process is essential for parasite survival under unfavorable conditions, such as those associated with starvation, low temperatures, and biocides. Furthermore, cysteine proteases have been implicated in the massive turnover of intracellular components required for encystation. Thus, strict modulation of the activities of cysteine proteases is required to protect Acanthamoeba from intracellular damage. However, mechanisms underlying the control of protease activity during encystation have not been established in Acanthamoeba. In the present study, we identified and characterized Acanthamoeba cysteine protease inhibitor (AcStefin), which was found to be highly expressed during encystation and to be associated with lysosomes by fluorescence microscopy. Recombinant AcStefin inhibited various cysteine proteases, including human cathepsin B, human cathepsin L, and papain. Transfection with small interfering RNA against AcStefin increased cysteine protease activity during encystation and resulted in incomplete cyst formation, reduced excystation efficiency, and a significant reduction in cytoplasmic area. Taken together, these results indicate that AcStefin is involved in the modulation of cysteine proteases and that it plays an essential role during the encystation of Acanthamoeba.
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http://dx.doi.org/10.1128/EC.00308-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3623446PMC
April 2013

Autophagy protein 16-mediated autophagy is required for the encystation of Acanthamoeba castellanii.

Mol Biochem Parasitol 2012 Jun 7;183(2):158-65. Epub 2012 Mar 7.

Department of Parasitology, Kyungpook National University School of Medicine, 101 Dongin-dong, Joong-gu, Daegu 700-422, Republic of Korea.

Autophagy, an evolutionarily conserved protein degradation pathway in eukaryotes, plays essential roles during starvation and cellular differentiation by eliminating unwanted and/or unnecessary cell material including organelles. Autophagy protein 16 (Atg16) is an essential component of the autophagic machinery. The present study identified and characterized an Atg16 homologue (AcAtg16) in Acanthamoeba, an opportunistic pathogen responsible for several distinct diseases in humans. AcAtg16 was highly expressed during encystation and was found to be associated with small or large vesicular structures that partially colocalized with autophagolysosomes. Small interfering RNA against AcAtg16 inhibited autophagosome formation and reduced the encystation efficiency of Acanthamoeba. Moreover, most mitochondria remained undigested in these knockdown cells. Taken together, these results indicate that AcAtg16 is involved in autophagosome formation and plays an essential role in the encystation of Acanthamoeba.
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http://dx.doi.org/10.1016/j.molbiopara.2012.02.013DOI Listing
June 2012

Expressed sequence tag analysis of the erythrocytic stage of Plasmodium berghei.

Korean J Parasitol 2011 Sep 30;49(3):221-8. Epub 2011 Sep 30.

Department of Parasitology, Kyungpook National University School of Medicine, Daegu 700-422, Korea.

Rodent malaria parasites, such as Plasmodium berghei, are practical and useful model organisms for human malaria research because of their analogies to the human malaria in terms of structure, physiology, and life cycle. Exploiting the available genetic sequence information, we constructed a cDNA library from the erythrocytic stages of P. berghei and analyzed the expressed sequence tag (EST). A total of 10,040 ESTs were generated and assembled into 2,462 clusters. These EST clusters were compared against public protein databases and 48 putative new transcripts, most of which were hypothetical proteins with unknown function, were identified. Genes encoding ribosomal or membrane proteins and purine nucleotide phosphorylases were highly abundant clusters in P. berghei. Protein domain analyses and the Gene Ontology functional categorization revealed translation/protein folding, metabolism, protein degradation, and multiple family of variant antigens to be mainly prevalent. The presently-collected ESTs and its bioinformatic analysis will be useful resources to identify for drug target and vaccine candidates and validate gene predictions of P. berghei.
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http://dx.doi.org/10.3347/kjp.2011.49.3.221DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3210838PMC
September 2011

Paragonimus westermani: identification and characterization of the fasciclin I domain-containing protein.

Exp Parasitol 2010 Jun 4;125(2):76-83. Epub 2010 Jan 4.

Department of Parasitology, Kyungpook National University School of Medicine, Daegu 700-422, Republic of Korea.

Paragonimus westermani is a trematode parasite that causes inflammatory lung disease as well as systemic infections in carnivorous mammals. The interaction of the parasite with host cells and paired worms is initiated by adhesion and plays an important role in parasite proliferation and differentiation. In this study, we isolated a cDNA encoding a P. westermani fasciclin I domain-containing protein (Pwfas-I). The fasiclin-I domain is suggested to be involved in cell adhesion, migration, and differentiation. Immunohistochemical analysis of P. westermani adult worms with polyclonal anti-Pwfas-I serum revealed immunoreactivity in the egg shells and the cells lining the sub-tegumental layer of adult worm throughout the contact regions of the cyst wall and paired worms. Using cell adhesion and spreading assays, we showed that Pwfas-I supports cell adhesion and spreading. Furthermore, we determined that the alphanubeta5 integrin was a functional receptor for the Pwfas-I. Taken together, these results suggest that Pwfas-I may be functional for the modulation of cell adhesion via binding with alphanubeta5 integrin in the extracellular matrix of Paragonimus.
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http://dx.doi.org/10.1016/j.exppara.2009.12.022DOI Listing
June 2010

M17 leucine aminopeptidase of the human malaria parasite Plasmodium vivax.

Mol Biochem Parasitol 2010 Mar 18;170(1):45-8. Epub 2009 Nov 18.

Department of Parasitology, Kyungpook National University School of Medicine, 700-422, Taegu, Republic of Korea.

Amino acids derived from hemoglobin are essential to protein synthesis required for growth and development of the Plasmodium vivax malaria parasite. M17 leucine aminopeptidase (LAP) is a cytosolic metallo-exopeptidase that catalyzes the removal of amino acids from the peptide generated in the process of hemoglobin degradation. Inhibitors of the enzyme have shown promise as drugs against Plasmodium infections, implicating aminopeptidases as a novel potential anti-malarial chemotherapy target. In this study, we isolated a cDNA encoding a 68kDa P. vivax LAP (PvLAP). Deduced amino acid sequence of PvLAP exhibited significant sequence homology with LAP from Plasmodium falciparum. Biochemical analysis of the recombinant PvLAP protein produced in Escherichia coli demonstrated preferential substrate specificity for the fluorogenic peptide Leu-7-amido-4-methylcoumarin hydroxide and inhibition by EDTA, 1,10-phenanthroline, and bestatin, which are conserved characteristics of the M17 family of LAP. PvLAP was optimally active at slightly alkaline pH and its activity was dependent on divalent metal ions. Based on the biochemical properties and immunofluorescence localization, PvLAP is concluded to represent a LAP in P. vivax. The enzyme is most likely responsible for the catabolism of host hemoglobin and, hence, represents a potential target of both P. falciparum and P. vivax chemotherapy.
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http://dx.doi.org/10.1016/j.molbiopara.2009.11.003DOI Listing
March 2010

Antibiotic susceptibility pattern of urinary isolates in Imphal (Manipur), India.

Nepal Med Coll J 2007 Sep;9(3):170-2

Department of Microbiology, Regional Institute of Medical Sciences, Imphal (Manipur), India.

The present study was conducted to detect aerobic causative agents of urinary tract infection (UTI) and their antibiogram pattern. This study was carried out in the Department of Microbiology, Regional Institute of Medical Sciences (RIMS), Imphal, Manipur, India. A total of 1,109 clean catched midstream urine samples were collected, out of which 459 (40.4%) samples grew potential pathogens causing UTI. Escherichia coli were the predominant 334 (72.8%) bacterial pathogen followed by Klebsiella species 66 (14.4%), non lactose fermenters 19 (4.1%), Pseudomonas species 16 (3.5%) and others. Most of the strains of E. coli were resistance to Ciprofloxacin whereas sensitive to Aminoglycoside. Most of the urinary isolates showed high degree of resistance to Tetracycline, Norfloxacin and Cotrimoxazole. Gentamycin was the drug of choice for most of the strains.
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September 2007