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Search Results: 1 - 10 of 154863 matches for " Kwang H. Choi "
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A comparison of DNA sequencing and the hydrolysis probe analysis (TaqMan assay) for knockdown resistance (kdr) mutations in Anopheles gambiae from the Republic of the Congo
Kwang Choi, Belinda L Spillings, Maureen Coetzee, Richard H Hunt, Lizette L Koekemoer
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-278
Abstract: A total of 52 pyrethroid and DDT resistant An. gambiae from Pointe-Noire (Congo-Brazzaville) were tested for detection of the two kdr mutations (kdr-e and kdr-w) that are known to occur in this species. Results from the hydrolysis probe analysis were compared to DNA sequencing to verify the accuracy of the probe analysis for this vector population.Fifty-one specimens were found to be An. gambiae S-form and one was a M/S hybrid. DNA sequencing revealed that more than half of the specimens (55.8%) carried both the kdr-e and kdr-w resistance mutations, seven specimens (13.5%) were homozygous for the kdr-e mutation, and 14 specimens (26.9%) were homozygous for the kdr-w mutation. A single individual was genotyped as heterozygous kdr-e mutation (1.9%) only and another as heterozygous kdr-w mutation (1.9%) only. Analysis using hydrolysis probe analysis, without adjustment of the allelic discrimination axes on the scatter plots, revealed six specimens (11.5%) carrying both mutations, 30 specimens (57.8%) as homozygous kdr-w, six specimens (11.5%) homozygous for the kdr-e mutation, one specimen (1.9%) heterozygous for the kdr-w mutation and one specimen (1.9%) present in wild type form. Eight of the specimens (15.4%) could not be identified using unadjusted hydrolysis probe analysis values. No heterozygous kdr-e mutations were scored when adjustment for the allelic discrimination axes was omitted. However, when the axes on the scatter plots were adjusted the results were consistent with those of the DNA sequence analysis, barring two individuals that were mis-scored in the hydrolysis probe analysis.Both the kdr-e and kdr-w mutations were abundant in An. gambiae S-form from Pointe-Noire. The hydrolysis probe analysis can lead to misleading results if adjustment to allelic discrimination axes is not investigated. This is mainly relevant when both kdr-e and kdr-w are present in a population in a high frequency. This report highlights the importance of concurrent screening for
4-1BB Signaling Breaks the Tolerance of Maternal CD8+ T Cells That Are Reactive with Alloantigens
Kwang H. Kim, Beom K. Choi, Jung D. Kim, Young H. Kim, Sun K. Lee, Jae H. Suh, Sang C. Lee, Sang W. Kang, Byoung S. Kwon
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045481
Abstract: 4-1BB (CD137, TNFRSF9), a member of the activation-induced tumor necrosis factor receptor family, is a powerful T-cell costimulatory molecule. It generally enhances CD8+ T responses and even breaks the tolerance of CD8+ T cells in an antigen-specific manner. In the present study we found that it was expressed in the placentas of pregnant mice and that its expression coincided with that of the immunesuppressive enzyme indoleamine 2,3-dioxygenase (IDO). Therefore, we investigated whether 4-1BB signaling is involved in fetal rejection using agonistic anti-4-1BB mAb and 4-1BB-deficient mice. Treatment with agonistic anti-4-1BB mAb markedly increased the rate of rejection of allogeneic but not syngeneic fetuses, and this was primarily dependent on CD8+ T cells. Complement component 3 (C3) seemed to be the effector molecule because 4-1BB triggering resulting in accumulation of C3 in the placenta, and this accumulation was also reversed by anti-CD8 mAb treatment. These findings demonstrate that 4-1BB triggering breaks the tolerance of CD8+ T cells to alloantigens in the placenta. Moreover, triggering 4-1BB protected the pregnant mice from Listeria monocytogenes (LM) infection, but led to rejection of semi-allogeneic fetuses. Therefore, given the cross-recognition of alloantigen by pathogen-reactive CD8+ T cells, the true function of 4-1BB may be to reverse the hypo-responsiveness of pathogen-reactive CD8+ T cells in the placenta in cases of infection, even if that risks losing the fetus.
Effects of typical and atypical antipsychotic drugs on gene expression profiles in the liver of schizophrenia subjects
Kwang H Choi, Brandon W Higgs, Serge Weis, Jonathan Song, Ida C Llenos, Jeannette R Dulay, Robert H Yolken, Maree J Webster
BMC Psychiatry , 2009, DOI: 10.1186/1471-244x-9-57
Abstract: We performed genome-wide expression profiling to study effects of typical antipsychotics and atypical antipsychotics in the postmortem liver of schizophrenia patients using microarrays (Affymetrix U133 plus2.0). We classified the subjects into typical antipsychotics (n = 24) or atypical antipsychotics (n = 26) based on their medication history, and compared gene expression profiles with unaffected controls (n = 34). We further analyzed individual antipsychotic effects on gene expression by sub-classifying the subjects into four major antipsychotic groups including haloperidol, phenothiazines, olanzapine and risperidone.Typical antipsychotics affected genes associated with nuclear protein, stress responses and phosphorylation, whereas atypical antipsychotics affected genes associated with golgi/endoplasmic reticulum and cytoplasm transport. Comparison between typical antipsychotics and atypical antipsychotics further identified genes associated with lipid metabolism and mitochondrial function. Analyses on individual antipsychotics revealed a set of genes (151 transcripts, FDR adjusted p < 0.05) that are differentially regulated by four antipsychotics, particularly by phenothiazines, in the liver of schizophrenia patients.Typical antipsychotics and atypical antipsychotics affect different genes and biological function in the liver. Typical antipsychotic phenothiazines exert robust effects on gene expression in the liver that may lead to liver toxicity. The genes found in the current study may benefit antipsychotic drug development with better therapeutic and side effect profiles.Differential therapeutic and side effects of typical antipsychotic (AP) and atypical AP drugs in schizophrenia have been documented [1,2]. Typical APs such as haloperidol and phenothiazines induce elevation of serum prolactin, extrapyramidal symptoms and tardive dyskinesia, whereas atypical APs such as clozapine and olanzapine induce metabolic syndromes and elevation of liver enzyme levels [3-
Expression Profiles of Mitochondrial Genes in the Frontal Cortex and the Caudate Nucleus of Developing Humans and Mice Selectively Bred for High and Low Fear
Kwang H. Choi, Thien Le, Jennifer McGuire, Jennifer Coyner, Brandon W. Higgs, Suad Diglisic, Luke R. Johnson, David M. Benedek, Robert J. Ursano
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049183
Abstract: A growing body of evidence suggests that mitochondrial function may be important in brain development and psychiatric disorders. However, detailed expression profiles of those genes in human brain development and fear-related behavior remain unclear. Using microarray data available from the public domain and the Gene Ontology analysis, we identified the genes and the functional categories associated with chronological age in the prefrontal cortex (PFC) and the caudate nucleus (CN) of psychiatrically normal humans ranging in age from birth to 50 years. Among those, we found that a substantial number of genes in the PFC (115) and the CN (117) are associated with the GO term: mitochondrion (FDR qv <0.05). A greater number of the genes in the PFC (91%) than the genes in the CN (62%) showed a linear increase in expression during postnatal development. Using quantitative PCR, we validated the developmental expression pattern of four genes including monoamine oxidase B (MAOB), NADH dehydrogenase flavoprotein (NDUFV1), mitochondrial uncoupling protein 5 (SLC25A14) and tubulin beta-3 chain (TUBB3). In mice, overall developmental expression pattern of MAOB, SLC25A14 and TUBB3 in the PFC were comparable to the pattern observed in humans (p<0.05). However, mice selectively bred for high fear did not exhibit normal developmental changes of MAOB and TUBB3. These findings suggest that the genes associated with mitochondrial function in the PFC play a significant role in brain development and fear-related behavior.
Putative psychosis genes in the prefrontal cortex: combined analysis of gene expression microarrays
Kwang Choi, Michael Elashoff, Brandon W Higgs, Jonathan Song, Sanghyeon Kim, Sarven Sabunciyan, Suad Diglisic, Robert H Yolken, Michael B Knable, E Fuller Torrey, Maree J Webster
BMC Psychiatry , 2008, DOI: 10.1186/1471-244x-8-87
Abstract: We performed a cross-study analysis of 7 gene expression microarrays that include both psychosis and non-psychosis subjects. These studies include over 400 microarray samples (163 individual subjects) on 3 different Affymetrix microarray platforms.We found that 110 transcripts are differentially regulated (p < 0.001) in psychosis after adjusting for confounding variables with a multiple regression model. Using a quantitative PCR, we validated a set of genes such as up-regulated metallothioneins (MT1E, MT1F, MT1H, MT1K, MT1X, MT2A and MT3) and down-regulated neuropeptides (SST, TAC1 and NPY) in the dorsolateral prefrontal cortex of psychosis patients.This study demonstrates the advantages of cross-study analysis in detecting consensus changes in gene expression across multiple microarray studies. Differential gene expression between individuals with and without psychosis suggests that psychosis may be a useful phenotypic variable to complement the traditional diagnosis categories.Kraepelin's 1896 dichotomous classification of functional psychoses into dementia praecox (schizophrenia) and manic-depressive insanity (bipolar disorder) is well known and has dominated most diagnostic systems in psychiatry. Less well known is the fact that two decades later, Kraepelin himself questioned the validity of his classificatory system, noting that "it is becoming increasingly clear that we cannot distinguish satisfactorily between these two illnesses and this brings home the suspicion that our formulation of the problem may be incorrect." [1,2] In recent years, increasing number of observers have shared Kraepelin's doubts, with some proposing instead a continuum hypothesis [3,4]. Clinically, there is much overlap of symptoms, and the intermediate category of schizoaffective disorder may imply an artificial preservation of the dichotomy between these two diagnoses [5]. The clinical gulf between individuals with bipolar II and those with bipolar I with psychotic features is marked,
Insecticide resistance in malaria vector mosquitoes at four localities in Ghana, West Africa
Richard H Hunt, Godwin Fuseini, Steve Knowles, Joseph Stiles-Ocran, Rolf Verster, Maria L Kaiser, Kwang Choi, Lizette L Koekemoer, Maureen Coetzee
Parasites & Vectors , 2011, DOI: 10.1186/1756-3305-4-107
Abstract: This paper presents baseline entomological data obtained during surveys conducted for four mining operations in Ghana, West Africa.The vast majority of the samples were identified as Anopheles gambiae S form with only a few M form specimens being identified from Tarkwa. Plasmodium falciparum infection rates ranged from 4.5 to 8.6% in An. gambiae and 1.81 to 8.06% in An. funestus. High survival rates on standard WHO bioassay tests were recorded for all insecticide classes except the organophosphates that showed reasonable mortality at all locations (i.e. > 90%). The West African kdr mutation was detected and showed high frequencies in all populations.The data highlight the complexity of the situation prevailing in southern Ghana and the challenges facing the malaria vector control programmes in this region. Vector control programmes in Ghana need to carefully consider the resistance profiles of the local mosquito populations in order to base their resistance management strategies on sound scientific data.Malaria remains today the biggest killer of children in Africa [1] and it demands increased attention from control authorities in affected countries. Multi-national corporations operating in Africa recognize the burden malaria places on their staff and its impact on their commercial operations [2,3]. There is an increasing move by these multi-nationals to control malaria within the boundaries of their activities, and in many cases, extending this control to the surrounding communities [4,5].The traditional methods of protecting work-forces using fogging, prophylaxis, repellents and handing out insecticide treated bed nets to workers (ITNs), have clearly not resulted in the desired outcome and companies are now implementing malaria control through the use of indoor residual house spraying [2,3]. Key to the success of these measures is knowledge of the local vector populations, the species identity, role in transmission and susceptibility to the four classes of insecti
A Study on Development of Balanced Scorecard for Management Evaluation Using Multiple Attribute Decision Making  [PDF]
Kwang Mo Yang, Young Wook Cho, Seung Hee Choi, Jae Hyun Park, Kyoung Sik Kang
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.33032
Abstract: Recently, most businesses have introduced a system for improving their responsibility to the customers in terms of job improvement. For example, small-quantity batch production increases cost but improve efficiency of management. Companies have been introduced the balanced scorecard to evaluate their management as part of improvement, while they suffer from many trials and errors. Many businesses still have difficulty in introducing balance scorecard concept in their process, but we suggest a method to successfully introduce the balance scorecard. This study aims to suggest a new performance measurement model reflecting relative importance of the key performance indicators for each factor. Our model is applied to several companies in real-world to validate the new model. Also, our study proposes a methodology for an adequate performance measurement using multiple attribute decision making.
Air Traffic Volume and Air Traffic Control Human Errors  [PDF]
Woo-Choon Moon, Kwang-Eui Yoo, Youn-Chul Choi
Journal of Transportation Technologies (JTTs) , 2011, DOI: 10.4236/jtts.2011.13007
Abstract: Navigable airspaces are becoming more crowded with increasing air traffic, and the number of accidents caused by human errors is increasing. The main objective of this paper is to evaluate the relationship between air traffic volume and human error in air traffic control (ATC). First, the paper identifies categories and elements of ATC human error through a review of existing literature, and a study through interviews and surveys of ATC safety experts. And then the paper presents the results of an experiment conducted on 52 air traffic controllers sampled from the Korean ATC organization to find out if there is any relationship between traffic volume and air traffic controller human errors. An analysis of the experiment clearly showed that several types of ATC human error are influenced by traffic volume. We hope that the paper will make its contribution to aviation safety by providing a realistic basis for securing proper manpower and facility in accordance with the level of air traffic volume.
Simultaneous identification of the Anopheles funestus group and Anopheles longipalpis type C by PCR-RFLP
Kwang Choi, Maureen Coetzee, Lizette L Koekemoer
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-316
Abstract: A total of 70 specimens from six species (An. funestus, An. funestus-like, An. parensis, Anopheles rivulorum, An. vaneedeni and An. leesoni) in the An. funestus group and An. longipalpis type C from Malawi, Mozambique, South Africa and Zambia were used for the study. A restriction fragment length polymorphism (RFLP) assay was designed based on the DNA sequence information in the GenBank database.The enzyme, EcoRI digested only An. longipalpis type C and An. funestus-like after the species-specific An. funestus group PCR assay. The An. longipalpis and An. funestus-like digestion profiles were characterized by three fragments, 376 bp, 252 bp and 211 bp for An. longipalpis type C and two fragments, 375 bp and 15 bp for An. funestus-like.An RFLP method for the group was developed that is more accurate and efficient than those used before. Hence, this assay would be useful for field-collected adult specimens to be identified routinely in malaria vector research and control studies.The Anopheles funestus group originally consisted of nine species [1,2]: the major African malaria vector An. funestus and eight minor or non-vectors, Anopheles aruni, Anopheles parensis, Anopheles vaneedeni, Anopheles confusus, Anopheles rivulorum, Anopheles leesoni, Anopheles brucei and Anopheles fuscivenosus. Subsequent studies on the systematics of the group have resulted in a reclassification of the group with An. funestus, An. aruni, An. parensis, An. confusus and An. vaneedeni being grouped together as members of the "An. funestus subgroup", An. rivulorum, An. rivulorum-like, An. brucei and An. fuscivenosus forming their own subgroup, and An. leesoni being classified with the Asian Anopheles minimus subgroup [3]. Recently, a new species has been described from Malawi, An. funestus-like [4], and this species falls within the An. funestus subgroup.In addition to the 10 species mentioned above, there are closely related species that are not included in the group because of morphological dif
Malaria vectors in Angola: distribution of species and molecular forms of the Anopheles gambiae complex, their pyrethroid insecticide knockdown resistance (kdr) status and Plasmodium falciparum sporozoite rates
Nelson Cuamba, Kwang Choi, Harold Townson
Malaria Journal , 2006, DOI: 10.1186/1475-2875-5-2
Abstract: During April 2001, mosquitoes were sampled by indoor pyrethrum spray collection from four sites in the semi-arid coastal provinces of Luanda and Benguela and two sites in Huambo province, in the humid tropical highlands. Collections took place towards the end of the rainy season and were used to determine the Anopheles species present, their sporozoite rates and the frequency of a kdr allele conferring resistance to pyrethroid insecticides.A PCR test for the Anopheles gambiae complex showed a preponderance of An. gambiae, with indoor resting densities ranging from 0.9 to 23.5 per house. Of 403 An. gambiae identified to molecular form, 93.5% were M-form and 6.5% S-form. M and S were sympatric at 4 sites but no M/S hybrids were detected. The highest proportion of S-form (20%) was in samples from Huambo, in the humid highlands. Anopheles funestus was found at one site near Luanda. The sporozoite rate of mosquitoes, determined by an ELISA test, was 1.9% for An. gambiae (n = 580) and 0.7% for An. funestus (n = 140). Of 218 An. gambiae (195 M-form and 23 S-form) genotyped for the West African kdr-resistance allele, all were homozygous susceptible.An. gambiae M-form is the most important and widespread malaria vector in the areas studied but more extensive studies of malaria vectors are required to support the malaria control programme in Angola. These should include standard insecticide resistance biossays and molecular assays that can detect both metabolic resistance and target site insensitivity.In West Africa, Anopheles gambiae, Anopheles arabiensis and Anopheles funestus are the main vectors of malaria, although Anopheles melas, a member of the An. gambiae complex, is known to be a malaria vector in some coastal areas [1-3].It has been shown that An. gambiae comprises two molecular forms, M and S, recognisable from rDNA sequence differences, either in the intergenic spacer [4] or in the internal transcribed spacer [5,6]. The genetic characteristics of these forms and
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