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Search Results: 1 - 10 of 202665 matches for " Reginaldo P;Hamilton "
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Isolation and Identification of 9-methylgermacrene-B as the Putative Sex Pheromone of Lutzomyia cruzi (Mangabeira, 1938) (Diptera: Psychodidae)
Brazil, Reginaldo P;Hamilton, JGC;
Memórias do Instituto Oswaldo Cruz , 2002, DOI: 10.1590/S0074-02762002000300030
Abstract: lutzomyia (lutzomyia) cruzi has been named as a probable vector of leishmania chagasi in corumbá, mato grosso do sul, brazil. taxonomically l. cruzi is closely related to the l. longipalpis species complex. females of l. cruzi and l. longipalpis are morphologically indistinguishable and associated males must be examined carefully to confirm identifications. chemical analysis hexane extracts of male l. cruzi has revealed the presence of a 9-methylgermacrene-b (c16), a homosesquiterpene (mw 218) previously shown to be the sex pheromone of one of the members of the l. longipalpis species complex.
Isolation and Identification of 9-methylgermacrene-B as the Putative Sex Pheromone of Lutzomyia cruzi (Mangabeira, 1938) (Diptera: Psychodidae)
Brazil Reginaldo P,Hamilton JGC
Memórias do Instituto Oswaldo Cruz , 2002,
Abstract: Lutzomyia (Lutzomyia) cruzi has been named as a probable vector of Leishmania chagasi in Corumbá, Mato Grosso do Sul, Brazil. Taxonomically L. cruzi is closely related to the L. longipalpis species complex. Females of L. cruzi and L. longipalpis are morphologically indistinguishable and associated males must be examined carefully to confirm identifications. Chemical analysis hexane extracts of male L. cruzi has revealed the presence of a 9-methylgermacrene-B (C16), a homosesquiterpene (mw 218) previously shown to be the sex pheromone of one of the members of the L. longipalpis species complex.
Identification of the sex pheromone of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) from Asunción, Paraguay
Reginaldo P Brazil, Norath Caballero, James Hamilton
Parasites & Vectors , 2009, DOI: 10.1186/1756-3305-2-51
Abstract: In this study, we present the results of a coupled gas chromatography - mass spectrometry analysis of the pheromones of males Lu. longipalpis captured in an endemic area of visceral leishmaniasis in Asunción, Paraguay. Our results show that Lu. longipalpis from this site produce (S)-9-methylgermacrene-B which has also been found in Lu. longipalpis from different areas of Brazil, Colombia and Central America.Visceral leishmaniasis is endemic in several areas of Paraguay with the reports of sporadic cases and consecutive increase in the last few years [1-3]. Asuncion in the Central Department of Paraguay has reported the largest numbers of human cases but other regions more distant from the capital, such as Bella Vista Norte, near the border with Brazil, Encarnacion, near the border with Argentina, and the Departments of Conception and Amambay y San Pedro have been considered as new endemic areas by the Paraguayan Health Secretary [4,5].As in most endemic areas, Lutzomyia longipalpis s.l. is the main vector of Leishmania (L.) infantum (Kinetoplastida: Trypanosomatidae), the causative agent of visceral leishmaniasis in South and Central America. Even though Lu. longipalpis is recognized as a species complex, no consensus has been established on the number of species present in the New World [6-13].Field and laboratory observations have shown that, prior to copulation, Lu. longipalpis s.l. males wing flutter. This behaviour is associated with pheromone release by males during courtship [14-16]. The sex pheromones are produced in glandular tissue that underlies the cuticle of the abdominal tergites. Those pheromone-disseminating structures are visible, as a pair of pale patches [17,18] on the fourth or third and fourth tergites and have been confirmed as the site of sex pheromone production [19]. There is no relationship between spot morphology and sex pheromone type [20]. Sex pheromones of the Lu. longipalpis species complex have been shown to be homosesquiterpenes (C16
Synthetic sex pheromone attracts the leishmaniasis vector Lutzomyia longipalpis to experimental chicken sheds treated with insecticide
Daniel P Bray, Graziella B Alves, Maria E Dorval, Reginaldo P Brazil, J GC Hamilton
Parasites & Vectors , 2010, DOI: 10.1186/1756-3305-3-16
Abstract: Addition of synthetic pheromone resulted in greater numbers of male and female sand flies being caught and killed at experimental chicken sheds sprayed with insecticide, compared to pheromone-less controls. Furthermore, a ten-fold increase in the amount of sex pheromone released from test sheds increased the number of females attracted and subsequently killed. Treating sheds with insecticide alone resulted in a significant decrease in numbers of males attracted to sheds (compared to pre-spraying levels), and a near significant decrease in numbers of females. However, this effect was reversed through addition of synthetic pheromone at the time of insecticide spraying, leading to an increase in number of flies attracted post-treatment.In field trials of commercially available different coloured sticky traps, yellow traps caught more males than blue traps when placed in chicken sheds. In addition, yellow traps fitted with 10 pheromone lures caught significantly more males than pheromone-less controls. However, while female sand flies showed a preference for both blue and yellow pheromone traps sticky traps over white traps in the laboratory, neither colour caught significant numbers of females in chicken sheds, either with or without pheromone.We conclude that synthetic pheromone could currently be most effectively deployed for sand fly control through combination with existing insecticide spraying regimes. Development of a standalone pheromone trap remains a possibility, but such devices may require an additional attractive host odour component to be fully effective.The sand fly Lutzomyia longipalpis (Diptera: Psychodidae) is the principle vector of Leishmania infantum chagasi (Kinetoplastida: Trypanosomatidiae), the causative agent of American visceral leishmaniasis (AVL) in Brazil and South America. Transmission occurs through bloodfeeding of female L. longipalpis on infected hosts [1], with domestic dogs the primary reservoir in urban and peri-urban areas. Treatmen
Synthetic Sex Pheromone in a Long-Lasting Lure Attracts the Visceral Leishmaniasis Vector, Lutzomyia longipalpis, for up to 12 Weeks in Brazil
Daniel P. Bray,Vicky Carter,Graziella B. Alves,Reginaldo P. Brazil,Krishna K. Bandi,James G. C. Hamilton
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002723
Abstract: Current control methodologies have not prevented the spread of visceral leishmaniasis (VL) across Brazil. Here, we describe the development of a new tool for controlling the sand fly vector of the disease: a long-lasting lure, which releases a synthetic male sex pheromone, attractive to both sexes of Lutzomyia longipalpis. This device could be used to improve the effectiveness of residual insecticide spraying as a means of sand fly control, attracting L. longipalpis to insecticide-treated animal houses, where they could be killed in potentially large numbers over a number of weeks. Different lure designs releasing the synthetic pheromone (±)-9-methylgermacrene-B (CAS 183158-38-5) were field-tested in Ara?atuba, S?o Paulo (SP). Experiments compared numbers of sand flies caught overnight in experimental chicken sheds with pheromone lures, to numbers caught in control sheds without pheromone. Prototype lures, designed to last one night, were first used to confirm the attractiveness of the pheromone in SP, and shown to attract significantly more flies to test sheds than controls. Longer-lasting lures were tested when new, and at fortnightly intervals. Lures loaded with 1 mg of pheromone did not attract sand flies for more than two weeks. However, lures loaded with 10 mg of pheromone, with a releasing surface of 15 cm2 or 7.5 cm2, attracted female L. longipalpis for up to ten weeks, and males for up to twelve weeks. Approximately five times more sand flies were caught with 7.5 cm2 10 mg lures when first used than occurred naturally in non-experimental chicken resting sites. These results demonstrate that these lures are suitably long-lasting and attractive for use in sand fly control programmes in SP. To our knowledge, this is the first sex pheromone-based technology targeting an insect vector of a neglected human disease. Further studies should explore the general applicability of this approach for combating other insect-borne diseases.
Should reproductively isolated populations of Lutzomyia longipalpis sensu lato receive taxonomically valid names?
Brand?o-Filho, Sinval P;Balbino, Valdir Q;Marcondes, Carlos B;Brazil, Reginaldo P;Hamilton, James G;Shaw, Jeffrey J;
Memórias do Instituto Oswaldo Cruz , 2009, DOI: 10.1590/S0074-02762009000800022
Abstract: a group of 18 research workers involved in different aspects of the biology of lutzomyia longipalpis discussed whether or not it is important to give taxonomically valid names to populations that have been defined by biological, biochemical and molecular methods to be reproductively isolated. the type material of this medically important species has been lost and because of this it was recommended that a colony should be established from insects captured in the region of the type area and that their description should serve as the basis for future descriptions. it was pointed out that there is a lack of uniformity in the naming of closely related american sand flies and that some of the differences between populations of lu. longipalpis are greater than those between accepted species. the majority of the participants agreed that the populations that have been defined in the literature as sibling species should be named.
Molecular and Behavioral Differentiation among Brazilian Populations of Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae)
Alejandra S. Araki,Felipe M. Vigoder,Luiz G. S. R. Bauzer,Gabriel E. M. Ferreira,Nataly A. Souza,Izeneide B. Araújo,James G. C. Hamilton,Reginaldo P. Brazil,Alexandre A. Peixoto
PLOS Neglected Tropical Diseases , 2009, DOI: 10.1371/journal.pntd.0000365
Abstract: Background Lutzomyia longipalpis is the primary vector of American visceral leishmaniasis. There is strong evidence that L. longipalpis is a species complex, but until recently the existence of sibling species among Brazilian populations was considered a controversial issue. In addition, there is still no consensus regarding the number of species occurring in this complex. Methodology/Principal Findings Using period, a gene that controls circadian rhythms and affects interpulse interval periodicity of the male courtship songs in Drosophila melanogaster and close relatives, we analyzed the molecular polymorphism in a number of L. longipalpis samples from different regions in Brazil and compared the results with our previously published data using the same marker. We also studied the male copulation songs and pheromones from some of these populations. The results obtained so far suggest the existence of two main groups of populations in Brazil, one group representing a single species with males producing Burst-type copulation songs and cembrene-1 pheromones; and a second group that is more heterogeneous and probably represents a number of incipient species producing different combinations of Pulse-type songs and pheromones. Conclusions/Significance Our results reveal a high level of complexity in the divergence and gene-flow among Brazilian populations of the L. longipalpis species complex. This raises important questions concerning the epidemiological consequences of this incipient speciation process.
Racionalidade e representa o: requisitos para a explora o dos limites do político
Pérez, Reginaldo Teixeira
Civitas , 2001,
Abstract: Examinam-se os conceitos de racionalidade e representa o na constitui o da ordem sócio-política. Busca-se identificar o conteúdo desses conceitos em alguns autores representativos do pensamento político moderno e contemporaneo, com ênfase no universo liberal. A partir de defini es provisórias dos conceitos de racionalidade e representa o, prop e-se o inter-relacionamento entre ambos, a partir dessa associa o, analisam-se suas resultantes sobre a ordem.
Influence of Clad Metal Chemistry on Stress Corrosion Cracking Behaviour of Stainless Steels Claddings in Chloride Solution  [PDF]
Edmilson O. Correa, Reginaldo P. Barbosa, Augusto J. A. Buschinelli, Eduardo M. Silva
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.25051
Abstract: The effect of clad metal composition on stress corrosion cracking (SCC) behavior of three types of SMAW filler metals (E308L-16, E309-16 and E316L-16), used for cladding components subjected to highly corrosive conditions, was investigated in boiling 43% MgCl2 solution. In order to evaluate the stress corrosion cracking susceptibility of the top layer, constant load tests and metallographic examinations in tested SCC specimens were conducted. The susceptibility to stress corrosion cracking was evaluated in terms of the time-to-fracture. Results showed that the E309-16 clad metal presented the best SCC resistance. This may be attributed to the presence of a discontinuous delta-ferrite network in the austenitic matrix, which acted as a barrier to cracks propagation. Concerning to E308-16 and E316L-16 clad metals, results showed that these presented a similar SCC test performance. Their higher SCC susceptibility may be attributed to the presence of continuous vermicular delta-ferrite in their microstructure.
Phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) of Alagoas state, northeast of Brazil
Andrade Filho, José D;Brazil, Reginaldo P;
Neotropical Entomology , 2009, DOI: 10.1590/S1519-566X2009000500022
Abstract: the phlebotomine sandflies of the state of alagoas are poorly known, with more than 40 years since the last report on sandflies in the state. in here, psathyromyia brasiliensis (costa lima), micropygomyia quinquefer (dyar,) and evandromyia termitophila (martins, falc?o & silva) are registered for the first time in alagoas. this report increases to nine the number of species collected in the state, including lutzomyia longipalpis (lutz & neiva), migonemyia migonei (fran?a), nyssomyia whitmani (antunes & coutinho) and nyssomyia intermedia (lutz & neiva), all vectors of leishmania in brazil.
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