What's new for 'Trypanosomatids' in PubMed

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Sent on Tuesday, 2010 Oct 12
Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
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PubMed Results

Items 1 - 10 of 15

1.	Eur J Clin Microbiol Infect Dis. 2010 Oct 9. [Epub ahead of print] Universal PCR assays for the differential detection of all Old World Leishmania species. Ogado Ceasar Odiwuor S, Ageed Saad A, De Doncker S, Maes I, Laurent T, El Safi S, Mbuchi M, Büscher P, Dujardin JC, Van der Auwera G. Department of Parasitology, Institute of Tropical Medicine Antwerp, Nationalestraat 155, 2000, Antwerp, Belgium. Abstract For the epidemiological monitoring and clinical case management of leishmaniasis, determination of the causative Leishmania species gains importance. Current assays for the Old World often suffer from drawbacks in terms of validation on a geographically representative sample set and the ability to recognize all species complexes. We want to contribute to standardized species typing for Old World leishmaniasis. We determined the ribosomal DNA internal transcribed spacer 1 sequence of 24 strains or isolates, and validated four species-specific polymerase chain reactions (PCRs) amplifying this target. They discriminate L. aethiopica, L. tropica, L. major, and the L. donovani complex, use the same cycling conditions, and include an internal amplification control. Our PCRs amplify 0.1 pg of Leishmania DNA, while being 100% specific for species identification on an extensive panel of geographically representative strains and isolates. Similar results were obtained in an endemic reference laboratory in Kenya. Species could also be identified in clinical specimens. The presented PCRs require only agarose gel detection, and have several other advantages over many existing assays. We outline potential problems, suggest concrete solutions for transferring the technique to other settings, and deliver the proof-of-principle for analyzing clinical samples.
	PMID: 20936316 [PubMed - as supplied by publisher]

2.	Bioorg Med Chem. 2010 Sep 15. [Epub ahead of print] Anti-leishmanial and anti-trypanosomal activities of 1,4-dihydropyridines: In vitro evaluation and structure-activity relationship study. Reimão JQ, Scotti MT, Tempone AG. Laboratory of Applied Toxinology on Antiparasitic Drugs, Department of Parasitology, Instituto Adolfo Lutz. Avenida Dr. Arnaldo, 351, 8° andar. Cerqueira Cesar, CEP 01246-902 São Paulo, SP, Brazil. Abstract Leishmaniasis and Chagas' disease constitute a relevant health and socio-economic problem in Latin America, Africa, and Asia. The therapeutic interventions rely on inefficient and highly toxic drugs with systemic side effects in patients. Considering the multiple biological activities of the calcium channel blockers and the high versatility of 1,4-dihydropyridines, eight clinically used 1,4-dihydropyridines (azelnidipine, amlodipine, cilnidipine, lercanidipine, nicardipine, nifedipine, nimodipine and nitrendipine) were in vitro tested against Leishmania and Trypanosoma cruzi parasites, and their cytotoxicity was tested against mammalian cells. In addition, a QSAR study was performed in order to delineate further structural requirements for the anti-protozoan activity and to predict the biological potency of 1,4-dihydropyridines. The tested compounds were effective against Leishmania (L.) amazonensis, Leishmania (V.)braziliensis, Leishmania (L.) chagasi, and Leishmania (L.) major promastigotes, L. (L.) chagasi intracellular amastigotes and T. cruzi trypomastigotes with 50% inhibitory concentration (IC(50)) values in the range of 2.6-181μM. The QSAR provided useful information about the structural features of the anti-protozoan activities, including diphenylpropyl and diphenylmethylazetidin groups at position 4 of the 1,4-dihydropyridine ring, allowing the prediction of two novel potential anti-protozoan analogs.
	PMID: 20934347 [PubMed - as supplied by publisher]

3.	Mol Biochem Parasitol. 2010 Oct 6. [Epub ahead of print] Reliable quantification of cell cycle-dependent mRNA abundance using fluorescence-activated cell sorting in Trypanosoma brucei. Bucerius F, Kador M, Boshart M, Janzen CJ. University of Munich (LMU), Department Biology I, Genetics, Großhaderner Str. 2-4, 82152 Martinsried, Germany. Abstract Very little is known about cell cycle-dependent regulation of mRNA in Trypanosoma brucei, the causative agent of African sleeping sickness. Methods to synchronize cell cycle progression are inefficient or subject the parasites to non-physiological conditions and stress. We developed a fluorescence-activated cell sorting-based method to analyze steady-state mRNA levels in individual cell cycle phases. Normalization of the data was the most challenging problem because internal standards for cell cycle-regulated genes are not available for trypanosomes. Hence, we introduced an external standard (so-called "spike") to compensate for technically derived variations in processing cells and RNA samples. Validation of this method with a limited number of genes unraveled a transient up-regulation during S and G2/M phases for all mRNAs analyzed.
	PMID: 20933544 [PubMed - as supplied by publisher]

4.	Enferm Infecc Microbiol Clin. 2010 Oct 5. [Epub ahead of print] [Clinical microbiology laboratory and imported parasitic diseases.] [Article in Spanish] Martín-Rabadán P, Martínez-Ruiz R, Cuadros J, Cañavate C. Servicio de Microbiología y Enfermedades Infecciosas, Consulta del Viajero, Hospital General Universitario Gregorio Marañón, Madrid, España. Abstract Imported parasitosis represents an increasingly frequent diagnostic challenge for microbiology laboratories. A surge in immigration and international travel has led to a rise in the number of imported cases of parasitosis, and this trend is expected to continue in the future. The present article addresses this challenge by reviewing recommended diagnostic approaches and tests. Currently, microscopy is always recommended when analysing blood samples for parasites. If malaria is suspected, rapid antigen testing (including at least HRP2 antigen) should also be performed. The work-up for suspected leishmaniasis should include serology, culture, and in selected cases detection of antigen in urine. In suspected Chagas disease, two different serological tests should be performed. PCR for blood protozoa is highly sensitive, although it cannot be used to rule out Chagas disease, since this condition may be present without parasitemia. Accurate diagnosis of intestinal amebiasis usually requires PCR or antigen detection tests. In helminthiasis, traditional microscopy may need to be complemented with other tests, such as agar plate culture for strongyloidiasis, Og4C3 antigen detection for bancroftian filariasis, and antibody detection test for filariasis and schistosomiasis.
	PMID: 20932605 [PubMed - as supplied by publisher]

5.	Mol Divers. 2010 Oct 8. [Epub ahead of print] First computational chemistry multi-target model for anti-Alzheimer, anti-parasitic, anti-fungi, and anti-bacterial activity of GSK-3 inhibitors in vitro, in vivo, and in different cellular lines. García I, Fall Y, Gómez G, González-Díaz H. Department of Organic Chemistry, University of Vigo, Vigo, Spain, iselapintos@yahoo.es. Abstract In the work described here, we developed the first multi-target quantitative structure-activity relationship (QSAR) model able to predict the results of 42 different experimental tests for GSK-3 inhibitors with heterogeneous structural patterns. GSK-3β inhibitors are interesting candidates for developing anti-Alzheimer compounds. GSK-3β are also of interest as anti-parasitic compounds active against Plasmodium falciparum, Trypanosoma brucei, and Leishmania donovani; the causative agents for Malaria, African Trypanosomiasis and Leishmaniosis. The MARCH-INSIDE technique was used to quickly calculate total and local polarizability, n-octanol/water partition coefficients, refractivity, van der Waals area and electronegativity values to 4,508 active/non-active compounds as well as the average values of these indexes for active compounds in 42 different biological assays. Both the individual molecular descriptors and the average values for each test were used as input for a linear discriminant analysis (LDA). We discovered a classification function which used in training series correctly classifies 873 out of 1,218 GSK-3 cases of inhibitors (97.4%) and 2,140 out of 2,163 cases of non-active compounds (86.1%) in the 42 different tests. In addition, the model correctly classifies 285 out of 406 GSK-3 inhibitors (96.3%) and 710 out of 721 cases of non-active compounds (85.4%) in external validation series. The result is important because, for the first time, we can use a single equation to predict the results of heterogeneous series of organic compounds in 42 different experimental tests instead of developing, validating, and using 42 different QSAR models. Lastly, a double ordinate Cartesian plot of cross-validated residuals (first ordinate), standard residuals (second ordinate), and leverages (abscissa) defined the domain of applicability of the model as a squared area within ±2 band for residuals and a leverage threshold of h = 0.0044.
	PMID: 20931280 [PubMed - as supplied by publisher]
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6.	J Glob Infect Dis. 2010 Sep;2(3):248-57. Human immunodeficiency virus and leishmaniasis. Ezra N, Ochoa MT, Craft N. Department of Medicine, Division of Dermatology, David Geffen School of Medicine at UCLA, Los Angeles, USA. Abstract The Leishmaniases are a group of diseases transmitted to humans by the bite of a sandfly, caused by protozoan parasites of the genus Leishmania. Various Leishmania species infect humans, producing a spectrum of clinical manifestations. It is estimated that 350 million people are at risk, with a global yearly incidence of 1-1.5 million for cutaneous and 500,000 for visceral Leishmaniasis (VL). VL is a major cause of morbidity and mortality in East Africa, Brazil and the Indian subcontinent. Co-infection with human immunodeficiency virus (HIV) alters the immune response to the disease. Here we review the immune response to Leishmania in the setting of HIV co-infection. Improved understanding of the immunology involved in co-infections may help in designing prophylactic and therapeutic strategies against Leishmaniasis.
	PMID: 20927287 [PubMed - in process]
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7.	PLoS Negl Trop Dis. 2010 Sep 28;4(9). pii: e829. Leishmania-specific surface antigens show sub-genus sequence variation and immune recognition. Depledge DP, Maclean LM, Hodgkinson MR, Smith BA, Jackson AP, Ma S, Uliana SR, Smith DF. Centre for Immunology and Infection, Department of Biology, Hull York Medical School, University of York, York, United Kingdom. Abstract BACKGROUND: A family of hydrophilic acylated surface (HASP) proteins, containing extensive and variant amino acid repeats, is expressed at the plasma membrane in infective extracellular (metacyclic) and intracellular (amastigote) stages of Old World Leishmania species. While HASPs are antigenic in the host and can induce protective immune responses, the biological functions of these Leishmania-specific proteins remain unresolved. Previous genome analysis has suggested that parasites of the sub-genus Leishmania (Viannia) have lost HASP genes from their genomes. METHODS/PRINCIPAL FINDINGS: We have used molecular and cellular methods to analyse HASP expression in New World Leishmania mexicana complex species and show that, unlike in L. major, these proteins are expressed predominantly following differentiation into amastigotes within macrophages. Further genome analysis has revealed that the L. (Viannia) species, L. (V.) braziliensis, does express HASP-like proteins of low amino acid similarity but with similar biochemical characteristics, from genes present on a region of chromosome 23 that is syntenic with the HASP/SHERP locus in Old World Leishmania species and the L. (L.) mexicana complex. A related gene is also present in Leptomonas seymouri and this may represent the ancestral copy of these Leishmania-genus specific sequences. The L. braziliensis HASP-like proteins (named the orthologous (o) HASPs) are predominantly expressed on the plasma membrane in amastigotes and are recognised by immune sera taken from 4 out of 6 leishmaniasis patients tested in an endemic region of Brazil. Analysis of the repetitive domains of the oHASPs has shown considerable genetic variation in parasite isolates taken from the same patients, suggesting that antigenic change may play a role in immune recognition of this protein family. CONCLUSIONS/SIGNIFICANCE: These findings confirm that antigenic hydrophilic acylated proteins are expressed from genes in the same chromosomal region in species across the genus Leishmania. These proteins are surface-exposed on amastigotes (although L. (L.) major parasites also express HASPB on the metacyclic plasma membrane). The central repetitive domains of the HASPs are highly variant in their amino acid sequences, both within and between species, consistent with a role in immune recognition in the host.
	PMID: 20927190 [PubMed - in process]
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8.	J Biol Chem. 2010 Oct 5. [Epub ahead of print] Crystal structure of leishmania major oligopeptidase B gives insight into the enzymatic properties of a trypanosomatid virulence factor. McLus key K, Paterson NG, Bland ND, Isaacs NW, Mottram JC. University of Glasgow, United Kingdom. Abstract Oligopeptidase B (OPB) is a serine peptidase with dibasic substrate specificity. It is found in bacteria, plants and trypanosomatid pathogens, where it has been identified as a virulence factor and potential drug target. In this study we expressed active recombinant Leishmania major OPB and provide the first structure of an oligopeptidase B at high resolution. The crystallographic study reveals that OPB comprises two domains, a catalytic and a propeller domain, linked together by a hinge region. The structure has been determined in complex with the oligopeptide, protease-inhibitor antipain, giving detailed information on the enzyme[']s active site and extended substrate binding pockets. It shows that Glu-621 plays a critical role in the S1 binding pocket and, along with Phe-603, is largely responsible for the enzyme[']s substrate specificity in P1. In the S2 binding pocket, Tyr-499 was shown to be important for substrate stability. The structure also allowed an investigation into the function of residues highlighted in other studies including Glu-623 which was predicted to be involved in the S1 binding pocket but is found forming an inter-domain hydrogen bond. Additional important salt bridges/hydrogen bonds between the two domains were observed, highlighting the significance of the domain interface in OPB. This work provides a foundation for the study of the role of OPBs as virulence factors in trypanosomatids. It could facilitate the development of specific OPB inhibitors with therapeutic potential by exploiting its unique substrate recognition properties as well as providing a model for OPBs in general.
	PMID: 20926390 [PubMed - as supplied by publisher]
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9.	Diagn Microbiol Infect Dis. 2010 Oct 4. [Epub ahead of print] Evaluation of 4 polymerase chain reaction protocols for cultured Leishmania spp. typing. Rocha MN, Margonari C, Presot IM, Soares RP. Laboratory of Medical Entomology, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz/FIOCRUZ, 30190-002 Belo Horizonte, MG, Brazil. Abstract Leishmaniasis is a disease caused by the protozoan Leishmania resulting in a variety of clinical manifestations, from self-healing skin lesions to fatal visceral disease. The development of polymerase chain reaction (PCR)-based techniques has made species identification easier, faster, and less labor intensive. The main targets for PCR amplification include kinetoplastid DNA (kDNA), miniexon, and conserved regions such as the internal transcribed spacer. The objective of this work was to evaluate 4 different PCR techniques designed to type Leishmania using laboratory strains. Parasites were subjected to 4 PCR procedures using specific Leishmania primers for miniexon (designated A1 and A2) and kDNA (designated B1 and B2, C1 and C2, and D1, D2 and D3). Discrimination between some species and the 2 main subgenera Leishmania and Viannia was achieved. Unweighted pair group method analysis resulted in the expected clustering of the 2 species from the subgenus Leishmania. However, some species in the subgenus Viannia could not be distinguished, representing a continued challenge for PCR-based protocols. Results are discussed in terms of advantages, limitations, and reproducibility of these 4 PCR-based techniques in the taxonomy of Leishmania.
	PMID: 20926219 [PubMed - as supplied by publisher]
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10.	Trans R Soc Trop Med Hyg. 2010 Oct 4. [Epub ahead of print] Advantages and limits of real-time PCR assay and PCR-restriction fragment length polymorphism for the identification of cutaneous Leishmania species in Tunisia. Ben Abda I, de Monbrison F, Bousslimi N, Aoun K, Bouratbine A, Picot S. Research Laboratory of Emerging Parasitosis (LR 05 SP 03), Pasteur Institute of Tunis,13, Place Pasteur. BP 74-1002 Tunis, Tunisia; Service Paludisme, Parasites du Sang et Mycologie Médicale, Hospices Civils de Lyon, 103 Grande Rue de la Croix Rousse, 69317 Lyon Cedex 04, France. Abstract Cutaneous leishmaniasis (CL), a public health problem in Tunisia, is associated to three species: Leishmania (L.) infantum, L. major and L. killicki. Accurate and sensitive procedures for the diagnostic of Leishmania infection and for species identification are required to enable adequate treatment and appropriate control measures. Several PCR-methods are applied for the diagnosis and the identification of Leishmania parasites such as PCR-restriction fragment length polymorphism (PCR-RFLP), DNA sequencing, hybridization probes and real-time PCR (RT-PCR). In this study, PCR-RFLP and RT-PCR were performed on skin scrapings from 27 patients with confirmed CL by microscopic examination, in order to compare their usefulness and efficiency for identification of Leishmania species in routine diagnostic laboratories. Identification of Leishmania species was successfully achieved in 96.3% and 81.5% respectively. Agreement between using internal transcribed spacer 1 (ITS1)-PCR-RFLP and kDNA-RT-PCR assays was 70% (19/27). Characterization problems using RT-PCR were mainly due to the difficulties in analyzing the melting temperatures. ITS1-PCR-RFLP and kDNA-RT-PCR presented an interesting alternative to conventional methods for the identification of Leishmania parasites from clinical samples. Both PCR assays can be used in a routine diagnostic, however, further prospective studies including largest sampling, are required to determine their performances in a routine use.
	PMID: 20926109 [PubMed - as supplied by publisher]
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