RESUMO
Pathogenic Gram-negative bacteria resistant to almost all ß-lactam antibiotics are a major public health threat. Zn(II)-dependent or metallo-ß-lactamases (MBLs) produced by these bacteria inactivate most ß-lactam antibiotics, including the carbapenems, which are "last line therapies" for life-threatening Gram-negative infections. NDM-1 is a carbapenemase belonging to the MBL family that is rapidly spreading worldwide. Regrettably, inhibitors of MBLs are not yet developed. Here we present the bisthiazolidine (BTZ) scaffold as a structure with some features of ß-lactam substrates, which can be modified with metal-binding groups to target the MBL active site. Inspired by known interactions of MBLs with ß-lactams, we designed four BTZs that behave as in vitro NDM-1 inhibitors with Ki values in the low micromolar range (from 7 ± 1 to 19 ± 3 µM). NMR spectroscopy demonstrated that they inhibit hydrolysis of imipenem in NDM-1-producing Escherichia coli. In vitro time kill cell-based assays against a variety of bacterial strains harboring blaNDM-1 including Acinetobacter baumannii show that the compounds restore the antibacterial activity of imipenem. A crystal structure of the most potent heterocycle (L-CS319) in complex with NDM-1 at 1.9 Å resolution identified both structural determinants for inhibitor binding and opportunities for further improvements in potency.
RESUMO
Genome sequences predict the presence of many 2-oxoglutarate (2OG)-dependent oxygenases of unknown biochemical and biological functions in Drosophila. Ribosomal protein hydroxylation is emerging as an important 2OG oxygenase catalyzed pathway, but its biological functions are unclear. We report investigations on the function of Sudestada1 (Sud1), a Drosophila ribosomal oxygenase. As with its human and yeast homologs, OGFOD1 and Tpa1p, respectively, we identified Sud1 to catalyze prolyl-hydroxylation of the small ribosomal subunit protein RPS23. Like OGFOD1, Sud1 catalyzes a single prolyl-hydroxylation of RPS23 in contrast to yeast Tpa1p, where Pro-64 dihydroxylation is observed. RNAi-mediated Sud1 knockdown hinders normal growth in different Drosophila tissues. Growth impairment originates from both reduction of cell size and diminution of the number of cells and correlates with impaired translation efficiency and activation of the unfolded protein response in the endoplasmic reticulum. This is accompanied by phosphorylation of eIF2α and concomitant formation of stress granules, as well as promotion of autophagy and apoptosis. These observations, together with those on enzyme homologs described in the companion articles, reveal conserved biochemical and biological roles for a widely distributed ribosomal oxygenase.
Assuntos
Proteínas de Drosophila/metabolismo , Drosophila/enzimologia , Homeostase/fisiologia , Prolil Hidroxilases/metabolismo , Biossíntese de Proteínas/fisiologia , Proteínas Ribossômicas/metabolismo , Animais , Animais Geneticamente Modificados , Apoptose/genética , Autofagia/genética , Western Blotting , Pesos e Medidas Corporais , Cromatografia Líquida , Primers do DNA/genética , Proteínas de Drosophila/genética , Corpo Adiposo/citologia , Feminino , Técnicas de Silenciamento de Genes , Hidroxilação , Prolil Hidroxilases/genética , Processamento de Proteína Pós-Traducional/fisiologia , Interferência de RNA , Reação em Cadeia da Polimerase em Tempo Real , Proteínas Ribossômicas/genética , Espectrometria de Massas em Tandem , Resposta a Proteínas não Dobradas/genéticaRESUMO
Rhodnius prolixus is one of the main vectors of Trypanosoma cruzi, causative agent of Chagas disease. In Central America, it was first discovered in 1915 in El Salvador, from where it spread northwest to Guatemala and Mexico, and southeast to Nicaragua and Costa Rica, arriving also in Honduras in the late 1950s. Indoor residual spraying (IRS) by the antimalaria services of Costa Rica prevented its spread southwards, and similar IRS programmes appear to have eliminated it from El Salvador by the late 1970s. In 1997, by resolution of the Ministers of Health of the seven Central American countries, a multinational initiative against Chagas disease (IPCA) was launched with one of the specific objectives being the elimination of R. prolixus from the region. As a result, more and more infested areas were encountered, and progressively sprayed using an IRS strategy already deployed against Triatoma infestans in the southern cone countries of South America. In 2008, Guatemala became the first of these countries to be formally certified as free of Chagas disease transmission due to R. prolixus. The other infested countries have since been similarly certified, and none of these has reported the presence of R. prolixus since June 2010. Further surveillance is required, but current evidence suggests that R. prolixus may now been eliminated from throughout the mesoamerican region, with a corresponding decline in the incidence of T. cruzi infections.
Assuntos
Vetores de Doenças , Controle de Insetos/métodos , Rhodnius/crescimento & desenvolvimento , Animais , América Central/epidemiologia , Doença de Chagas/epidemiologia , Doença de Chagas/prevenção & controleRESUMO
We present an overview of the two main strategies for the primary (vector control) and secondary (patient care) prevention of Chagas disease (CD). We identify major advances, knowledge gaps, and key research needs in both areas. Improved specific chemotherapy, including more practical formulations (e.g., paediatric) or combinations of existing drugs, and a better understanding of pathogenesis, including the relative weights of parasite and host genetic makeup, are clearly needed. Regarding CD vectors, we find that only about 10-20% of published papers on triatomines deal directly with disease control. We pinpoint the pitfalls of the current consensus on triatomine systematics, particularly within the Triatomini, and suggest how some straightforward sampling and analytical strategies would improve research on vector ecology, naturally leading to sounder control-surveillance schemes. We conclude that sustained research on CD prevention is still crucial. In the past, it provided not only the know-how, but also the critical mass of scientists needed to foster and consolidate CD prevention programmes; in the future, both patient care and long-term vector control would nonetheless benefit from more sharply focused, problem-oriented research.
Assuntos
Antiprotozoários/uso terapêutico , Doença de Chagas/epidemiologia , Doença de Chagas/prevenção & controle , Controle de Insetos/métodos , Insetos Vetores , Triatominae/parasitologia , Animais , Pesquisa Biomédica/tendências , Doença de Chagas/tratamento farmacológico , Humanos , Triatominae/crescimento & desenvolvimentoRESUMO
BACKGROUND: Among Chagas disease triatomine vectors, the largest genus, Triatoma, includes species of high public health interest. Triatoma dimidiata, the main vector throughout Central America and up to Ecuador, presents extensive phenotypic, genotypic, and behavioral diversity in sylvatic, peridomestic and domestic habitats, and non-domiciliated populations acting as reinfestation sources. DNA sequence analyses, phylogenetic reconstruction methods, and genetic variation approaches are combined to investigate the haplotype profiling, genetic polymorphism, phylogeography, and evolutionary trends of T. dimidiata and its closest relatives within Triatoma. This is the largest interpopulational analysis performed on a triatomine species so far. METHODOLOGY AND FINDINGS: Triatomines from Mexico, Guatemala, Honduras, Nicaragua, Panama, Cuba, Colombia, Ecuador, and Brazil were used. Triatoma dimidiata populations follow different evolutionary divergences in which geographical isolation appears to have had an important influence. A southern Mexican-northern Guatemalan ancestral form gave rise to two main clades. One clade remained confined to the Yucatan peninsula and northern parts of Chiapas State, Guatemala, and Honduras, with extant descendants deserving specific status. Within the second clade, extant subspecies diversity was shaped by adaptive radiation derived from Guatemalan ancestral populations. Central American populations correspond to subspecies T. d. dimidiata. A southern spread into Panama and Colombia gave the T. d. capitata forms, and a northwestern spread rising from Guatemala into Mexico gave the T. d. maculipennis forms. Triatoma hegneri appears as a subspecific insular form. CONCLUSIONS: The comparison with very numerous Triatoma species allows us to reach highly supported conclusions not only about T. dimidiata, but also on different, important Triatoma species groupings and their evolution. The very large intraspecific genetic variability found in T. dimidiata sensu lato has never been detected in a triatomine species before. The distinction between the five different taxa furnishes a new frame for future analyses of the different vector transmission capacities and epidemiological characteristics of Chagas disease. Results indicate that T. dimidiata will offer problems for control, although dwelling insecticide spraying might be successful against introduced populations in Ecuador.
Assuntos
Doença de Chagas/transmissão , Variação Genética/genética , Insetos Vetores/genética , Filogenia , Triatoma/classificação , Triatoma/genética , Animais , América Central , DNA Ribossômico/genética , Haplótipos , Insetos Vetores/classificação , Dados de Sequência MolecularRESUMO
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.
Assuntos
Animais , Cães , Antiparasitários/uso terapêutico , Doença de Chagas/veterinária , Doenças do Cão/tratamento farmacológico , Ivermectina/uso terapêutico , Rhipicephalus sanguineus/efeitos dos fármacos , Infestações por Carrapato/veterinária , Trypanosoma cruzi/efeitos dos fármacos , Doença Aguda , Doença Crônica , Doença de Chagas/tratamento farmacológico , Doença de Chagas/parasitologia , Doenças do Cão/parasitologia , Rhipicephalus sanguineus/parasitologia , Rhodnius/efeitos dos fármacos , Rhodnius/parasitologia , Fatores de Tempo , Resultado do Tratamento , Infestações por Carrapato/tratamento farmacológico , Triatoma/efeitos dos fármacos , Triatoma/parasitologiaRESUMO
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.
Assuntos
Antiparasitários/uso terapêutico , Doença de Chagas/veterinária , Doenças do Cão/tratamento farmacológico , Ivermectina/uso terapêutico , Rhipicephalus sanguineus/efeitos dos fármacos , Infestações por Carrapato/veterinária , Trypanosoma cruzi/efeitos dos fármacos , Doença Aguda , Animais , Doença de Chagas/tratamento farmacológico , Doença de Chagas/parasitologia , Doença Crônica , Doenças do Cão/parasitologia , Cães , Rhipicephalus sanguineus/parasitologia , Rhodnius/efeitos dos fármacos , Rhodnius/parasitologia , Infestações por Carrapato/tratamento farmacológico , Fatores de Tempo , Resultado do Tratamento , Triatoma/efeitos dos fármacos , Triatoma/parasitologiaRESUMO
O controle de triatomíneos é dificultado pela capacidade de reinvasäo das casas por exemplares silvestres. Entre agosto/96 e dezembro97 realizou-se, no Ceará, um estudo a respeito da reinfestaçäo das casas após borrifaçäo. Das 277 Unidades Domiciliares - UD - pesquisadas, 40,8 por cento estavam infestadas (21,7 por cento dos intradomicílios e 35,4 por cento dos peridomicílios). Dos 433 triatomíneos capturados, 207 eram Triatoma brasiliensis (48,8 por cento no intradomicílio, média de 1,8 insetos/casa) e 226 Triatoma pseudomaculata (97,3 por cento no peridomicílio). Ocorre um único ciclo anual do T.brasiliensis, e dois ciclos anuais do T. pseudomaculata. Quatro meses após a borrifaçäo, 9,7 por cento das unidades domiciliares permaneciam positivas, principalmente no peridomicílio; 10,3 por cento das UD foram positivas em todas as avaliaçöes. O teste de suscetibilidade biológica à deltametrina revelou a persistência do inseticida no intradomicílio até nove meses após a borrifaçäo. A prevalência global da infecçäo humana foi de 5,7 por cento, tendo sido positivas cinco crianças menores de dez anos. Considerando-se a alta pressäo de recolonizaçäo a partir de exemplares silvestres, propöe-se, como metodologia de controle, um sistema misto da avaliaçäo tradicional e a vigilância epidemiológica.
Assuntos
Triatoma , Controle de Vetores de DoençasRESUMO
Têm-se reportado a ocorrência de quatro padröes cromáticos e diferentes padröes morfológicos, genéticos e ecológicos de Triatoma brasiliensis no semi-árido nordestino do Brasil, regiäo onde é o mais importante vetor da doença de Chagas. Para verificar diferenças citogenéticas nessas populaçöes, foram analisados seus cariótipos e o comportamento cromossomial durante o processo meiótico em exemplares machos. Observou-se que o T. brasiliensis mostra características cromossômicas distintas e específicas entre as quatro populaçöes, diferindo daquelas observadas em outras espécies de triatomíneos. No entanto, diferenças citogenéticas näo foram observadas entre as quatro populaçöes de T. brasiliensis, o que poderia indicar que as referidas populaçöes ainda se encontram em uma etapa inicial do processo de diferenciaçäo, ainda näo envolvendo a organizaçäo cromossomial.
Assuntos
Triatoma/citologia , CariotipagemRESUMO
Resume-se a sistemática das 130 espécies de triatomíneos atualmente reconhecidas, com os elementos principais de sua evoluçäo. Existem evidências crescentes para a origem polifilética da subfamília. As diferentes tribos e grupos de espécies que a compöem teriam surgido recentemente, a partir de diferentes linhagens de reduviídeos.