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Search Results: 1 - 10 of 306221 matches for " Christopher J. Schofield "
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Biosystematics and evolution of the Triatominae
Schofield, Christopher J.;
Cadernos de Saúde Pública , 2000, DOI: 10.1590/S0102-311X2000000800010
Abstract: in this paper we summarize the systematics of the 130 currently recognized species of triatominae and the key features of their evolutionary background. there is increasing evidence that the subfamily has polyphyletic origins, with the various tribes and species groups probably arising from different reduviid lineages in relatively recent times.
Biosystematics and evolution of the Triatominae
Schofield Christopher J.
Cadernos de Saúde Pública , 2000,
Abstract: In this paper we summarize the systematics of the 130 currently recognized species of Triatominae and the key features of their evolutionary background. There is increasing evidence that the subfamily has polyphyletic origins, with the various tribes and species groups probably arising from different reduviid lineages in relatively recent times.
Elimination of Rhodnius prolixus in Central America
Ken Hashimoto, Christopher J Schofield
Parasites & Vectors , 2012, DOI: 10.1186/1756-3305-5-45
Abstract: By August 2011, all the previously endemic countries of Central America had been formally certified as free of Chagas disease transmission due to their main domestic vector, Rhodnius prolixus. None of these countries, nor Mexico, has reported the presence of this vector since June 2010, suggesting that R. prolixus may now have been completely eliminated from the mesoamerican region. This is not to say that Chagas disease itself has been eliminated, since there is not only a residue of previously infected cases, but there is also active transmission in some areas due to other vector species - especially Triatoma dimidiata. Nevertheless, the results suggest that the burden of transmission has been substantially reduced. This review summarises the background and progress of the multinational initiative against Chagas disease transmission carried out in the Central American countries (known as IPCA - Iniciativa de los Países de Centro América para la Interrupción de la Transmisión Vectorial, Transfusional y Atención Médica de la Enfermedad de Chagas).Information for the review has come from published scientific articles, reports of national Chagas disease control programmes, reports and presentations of annual meetings of the IPCA initiative, and personal communications. In mapping the historical distribution of R. prolixus (Figure 1) the location of some areas or villages was only approximate - some recent documents offer exact coordinates of infested villages, but most publications prior to the mid-1990s identified localities only by administrative departments or municipalities and for these, geographically centric points were selected.Rhodnius prolixus (Hemiptera, Reduviidae, Triatominae) is one of the most efficient vectors of Trypanosoma cruzi, the causative agent of Chagas disease. It is assumed to have evolved from the ancestral forms of other Rhodniini in or around the Amazon region of South America, becoming highly adapted to domestic and peridomestic habitats
Hypoxia-dependent sequestration of an oxygen sensor by a widespread structural motif can shape the hypoxic response - a predictive kinetic model
Bernhard Schmierer, Béla Novák, Christopher J Schofield
BMC Systems Biology , 2010, DOI: 10.1186/1752-0509-4-139
Abstract: To analyse if and in which way the FIH/ARD protein interaction affects HIF-activity, we created a rate equation model. Our model predicts that an oxygen-regulated sequestration of FIH by ARD proteins significantly shapes the input/output characteristics of the HIF system. The FIH/ARD protein interaction is predicted to create an oxygen threshold for HIFα CAD-hydroxylation and to significantly sharpen the signal/response curves, which not only focuses HIFα CAD-hydroxylation into a defined range of oxygen tensions, but also makes the response ultrasensitive to varying oxygen tensions. Our model further suggests that the hydroxylation status of the ARD protein pool can encode the strength and the duration of a hypoxic episode, which may allow cells to memorise these features for a certain time period after reoxygenation.The FIH/ARD protein interaction has the potential to contribute to oxygen-range finding, can sensitise the response to changes in oxygen levels, and can provide a memory of the strength and the duration of a hypoxic episode. These emergent properties are predicted to significantly shape the characteristics of HIF activity in animal cells. We argue that the FIH/ARD interaction should be taken into account in studies of the effect of pharmacological inhibition of the HIF-hydroxylases and propose that the interaction of a signalling sensor with a large group of proteins might be a general mechanism for the regulation of signalling pathways.In animals, the response to hypoxia is mediated by an α,β-heterodimeric transcription factor, the hypoxia inducible factor or HIF. In humans, there are three different HIFα isoforms, with HIF1α and HIF2α being better characterised than HIF3α. The HIFβ subunit is identical with the aryl hydrocarbon receptor nuclear translocator (ARNT). Both the level and transcriptional activity of HIF are regulated by post-translational hydroxylation of the HIFα, but not HIFβ, subunit. In the presence of sufficient oxygen, HIF1α and HIF2
Methyl 6-amino-6-oxohexanoate
Tobias Gruber,Christopher J. Schofield,Amber L. Thompson
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812003303
Abstract: The title compound, C7H13NO3, adopts an approximately planar conformation. The torsion angles in the aliphatic chain between the carbonyl group C atoms range from 172.97 (14) to 179.38 (14)° and the r.m.s. deviation of all non-H atoms is 0.059 . The crystal packing is dominated by two strong N—H...O hydrogen bonds involving the amide groups and forming R22(8) rings and C(4) chains. Overall, a two-dimensional network parallel to (100) is formed. A weak intermolecular C—H...O interaction is also present.
3-Methoxy-3-oxopropanaminium chloride
Tobias Gruber,Christopher J. Schofield,Amber L. Thompson
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812003297
Abstract: In the title compound, C4H10NO2+·Cl , the central ethylene bond of the cation adopts a gauche conformation. The three H atoms of the –NH3+ group are engaged in strong and highly directional intermolecular N—H...Cl hydrogen bonds, which result in a tape-like arrangement along [010] of the respective ion pairs. In addition, weak intermolecular C—H...Cl and C—H...O interactions are present.
Ticks, ivermectin, and experimental Chagas disease
Dias, Jo?o Carlos Pinto;Schofield, Christopher J;Machado, Evandro MM;Fernandes, Alexandre José;
Memórias do Instituto Oswaldo Cruz , 2005, DOI: 10.1590/S0074-02762005000800002
Abstract: following an infestation of dogticks in kennels housing dogs used for long-term studies of the pathogenesis of chagas disease, we examined the effect of ivermectin treatment on the dogs, ticks, trypanosome parasites, and also on triatomine vectors of chagas disease. ivermectin treatment was highly effective in eliminating the ticks, but showed no apparent effect on the dogs nor on their trypanosome infection. triatominae fed on the dogs soon after ivermectin treatment showed high mortality, but this effect quickly declined for bugs fed at successive intervals after treatment. in conclusion, although ivermectin treatment may have a transient effect on peridomestic populations of triatominae, it is not the treatment of choice for this situation. the study also showed that although the dogticks could become infected with trypanosoma cruzi, this only occurred when feeding on dogs in the acute phase of infection, and there was no evidence of subsequent parasite development in the ticks.
Chromosome homogeneity in populations of Triatoma brasiliensis Neiva 1911 (Hemiptera - Reduviidae - Triatominae)
Panzera, Francisco;Pérez, Ruben;Nicolini, Paula;Hornos, Sonia;Costa, Jane;Borges, érika;Diotaiuti, Liléia;Schofield, Christopher J.;
Cadernos de Saúde Pública , 2000, DOI: 10.1590/S0102-311X2000000800009
Abstract: triatoma brasiliensis is the most important vector of chagas disease in the semiarid zone of the northeast of brazil. several authors have reported the occurrence of four chromatic patterns with morphological, ecological, and genetic differences. in order to determine the existence of cytogenetic differentiation between these chromatic forms, we analyzed their karyotypes and the chromosome behavior during the male meiotic process. triatoma brasiliensis shows distinct and specific chromosome characteristics, which differ from those observed in all other triatomine species. however, no cytogenetic differences were observed between the four chromatic forms of t. brasiliensis. the lack of chromosome differentiation among them could indicate that the populations of this species are in a process of differentiation that does not involve their chromosomal organization.
Analysis of Jmjd6 Cellular Localization and Testing for Its Involvement in Histone Demethylation
Phillip Hahn,Ivonne Wegener,Alison Burrells,Jens B?se,Alexander Wolf,Christian Erck,Danica Butler,Christopher J. Schofield,Angelika B?ttger,Andreas Lengeling
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013769
Abstract: Methylation of residues in histone tails is part of a network that regulates gene expression. JmjC domain containing proteins catalyze the oxidative removal of methyl groups on histone lysine residues. Here, we report studies to test the involvement of Jumonji domain-containing protein 6 (Jmjd6) in histone lysine demethylation. Jmjd6 has recently been shown to hydroxylate RNA splicing factors and is known to be essential for the differentiation of multiple tissues and cells during embryogenesis. However, there have been conflicting reports as to whether Jmjd6 is a histone-modifying enzyme.
Aspectos operacionais do controle do Triatoma brasiliensis
Diotaiuti, Liléia;Faria Filho, Osvaldo F.;Carneiro, Francisco C. F.;Dias, Jo?o Carlos Pinto;Pires, Herton Helder R.;Schofield, Christopher J.;
Cadernos de Saúde Pública , 2000, DOI: 10.1590/S0102-311X2000000800006
Abstract: vector control strategies against indigenous species is not easy, due to their capacity to reinvade treated premises from sylvatic ecotopes. between august 1996 and december 1997 we conducted a study on reinfestation of houses after spraying in a county in the state of ceará. of 277 houses examined, 113 (40.8%) were infested (21.7% intradomiciliary and 35.4% peridomiciliary). of the 433 triatominae collected, 207 were triatoma brasiliensis (49% of which intradomiciliary, with a mean of 1.8 insects/house) and 226 were triatoma pseudomaculata (97% peridomiciliary). the age structure of the two indicated a univoltine development cycle for t. brasiliensis and two cycles per year for t. pseudomaculata. four months after spraying with deltamethrin sc 25mg ia/m2, 9.7% of the houses were still positive, mainly with peridomestic infestations. intradomiciliary wall bioassays showed persistence of the insecticide up to 9 months after spraying. considering the high potential for recolonization of treated premises from sylvatic foci, we propose an operational strategy combining traditional evaluations and community-based surveillance with increased selective interventions and community education.
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