Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 12 )

2018 ( 22 )

2017 ( 27 )

2016 ( 25 )

Custom range...

Search Results: 1 - 10 of 15507 matches for " Pedro Berzosa "
All listed articles are free for downloading (OA Articles)
Page 1 /15507
Display every page Item
Molecular markers in Plasmodium falciparum linked to resistance to anti-malarial drugs in samples imported from Africa over an eight-year period (2002-2010): impact of the introduction of artemisinin combination therapy
Aranzazu Amor, Carlos Toro, Amalia Fernández-Martínez, Margarita Baquero, Agustín Benito, Pedro Berzosa
Malaria Journal , 2012, DOI: 10.1186/1475-2875-11-100
Abstract: A first group of samples was taken in the period between June 2002 and June 2006 (n = 113); a second group in the period between November 2008 and August 2010 (n = 46). Several alleles were analysed by nested PCR-RFLP: 51, 59, 108, 164, in the pfdhfr gene; 436, 437, 540, 581, in the pfdhps gene; 86, 1246, in the pfmdr1 gene and 76, in the pfcrt gene. The prevalence of alleles in the groups was compared with the chi-squared or Fisher's exact tests.The pfdhfr N51I, C59R and S108N were over to 90% in the two groups; all samples had the I164. In the pfdhps, 437 G and 581 G, increased up to 80% and 10.9% (p = 0.024), respectively in the second group. The 540 G decreases (24% to 16.%) and the 436A disappears at the end of the follow-up (p = 0.004) in the second group. The 76I-pfcrt stayed over 95% in the two groups. Prevalence of 86Y-pfmdr1 decreased over eight years.Pharmacological pressure affects the resistance strains prevalence. As for SP, the disappearance of 436A and the decrease in 540 G suggest that these mutations are not fixed. On the other hand, studies carried out after ACT introduction show there was a selection of strains carrying the SNPs N86Y, D1246Y in pfmdr1. In this work, the prevalence of pfmdr1- D1246Y is increasing, perhaps as a result of selective pressure by ACT. Continued surveillance is essential to monitor the effectiveness of treatments.Malaria treatment is an essential tool to control Plasmodium falciparum disease in endemic countries. Resistance to currently available drugs is one of his main problems [1]. Several mutations linked to resistance have been described in different genes of P. falciparum genome. These mutations take place spontaneously in the parasite, though pharmacological pressure is one of the most important factors involved in their spread [2].Resistance to chloroquine appears nowadays in all regions where P. falciparum is present in Africa [3]. The main determinant of chloroquine resistance is the K76I mutation of the pfcrt
Duffy Negative Antigen Is No Longer a Barrier to Plasmodium vivax – Molecular Evidences from the African West Coast (Angola and Equatorial Guinea)
Cristina Mendes,Fernanda Dias,Joana Figueiredo,Vicenta Gonzalez Mora,Jorge Cano,Bruno de Sousa,Virgílio E. do Rosário,Agustin Benito,Pedro Berzosa,Ana Paula Arez
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001192
Abstract: Background Plasmodium vivax shows a small prevalence in West and Central Africa due to the high prevalence of Duffy negative people. However, Duffy negative individuals infected with P. vivax have been reported in areas of high prevalence of Duffy positive people who may serve as supply of P. vivax strains able to invade Duffy negative erythrocytes. We investigated the presence of P. vivax in two West African countries, using blood samples and mosquitoes collected during two on-going studies. Methodology/Findings Blood samples from a total of 995 individuals were collected in seven villages in Angola and Equatorial Guinea, and 820 Anopheles mosquitoes were collected in Equatorial Guinea. Identification of the Plasmodium species was achieved by nested PCR amplification of the small-subunit rRNA genes; P. vivax was further characterized by csp gene analysis. Positive P. vivax-human isolates were genotyped for the Duffy blood group through the analysis of the DARC gene. Fifteen Duffy-negative individuals, 8 from Equatorial Guinea (out of 97) and 7 from Angola (out of 898), were infected with two different strains of P. vivax (VK210 and VK247). Conclusions In this study we demonstrated that P. vivax infections were found both in humans and mosquitoes, which means that active transmission is occurring. Given the high prevalence of infection in mosquitoes, we may speculate that this hypnozoite-forming species at liver may not be detected by the peripheral blood samples analysis. Also, this is the first report of Duffy negative individuals infected with two different strains of P. vivax (VK247 and classic strains) in Angola and Equatorial Guinea. This finding reinforces the idea that this parasite is able to use receptors other than Duffy to invade erythrocytes, which may have an enormous impact in P. vivax current distribution.
Microscopy and molecular biology for the diagnosis and evaluation of malaria in a hospital in a rural area of Ethiopia
Maria A Santana-Morales, Raquel N Afonso-Lehmann, Maria A Quispe, Francisco Reyes, Pedro Berzosa, Agustin Benito, Basilio Valladares, Enrique Martinez-Carretero
Malaria Journal , 2012, DOI: 10.1186/1475-2875-11-199
Abstract: A cross-sectional survey of 471 individuals was carried out in a hospital in the rural area of Gambo (Ethiopia). Blood samples were prepared for microscopic observation and collected in filter paper for Seminested-Multiplex PCR (SnM-PCR) and real time PCR (qPCR) testing. The SnM-PCR was considered as the gold standard technique and compared with the rest. Thus, agreement between SnM-PCR and LM was determined by calculating Kappa Statistics and correlation between LM and qPCR quantification was calculated by pair-wise correlation co-efficient.Samples analysed by LM and SnM-PCR were positive for Plasmodium sp. 5.5% and 10.5%, respectively. Sensitivity was 52.2% by LM and 70% by qPCR. Correlation co-efficient between microscopy counts and qPCR densities for Plasmodium vivax was R2?=?0.586. Prevalence was estimated at 7% (95% CI: 4.7–9.3). Plasmodium vivax was the dominant species detected and the difference was statistically significant (χ2?=?5.121 p?<?0.05). The highest prevalence of the parasite (10.9%) was observed in age groups under 15?years old.Accurate malaria diagnostic methods have a great effect in the reduction of the number of malaria-infected individuals. SnM-PCR detection of malaria parasites may be a very useful complement to microscopic examination in order to obtain the real prevalence of each Plasmodium species. Although SnM-PCR shows that it is a good tool for the determination of Plasmodium species, today light microscopy remains the only viabletool for malaria diagnosis in developing countries. Therefore, re-inforcement in the training of microscopists is essential for making the correct diagnosis of malaria. Plasmodium vivax was the predominant species in Gambo, a meso-endemic area for this species.
Detection of high levels of mutations involved in anti-malarial drug resistance in Plasmodium falciparum and Plasmodium vivax at a rural hospital in southern Ethiopia
Patricia Mula, Amalia Fernández-Martínez, Aida de Lucio, Jose Ramos, Francisco Reyes, Vicenta González, Agustín Benito, Pedro Berzosa
Malaria Journal , 2011, DOI: 10.1186/1475-2875-10-214
Abstract: A total of 1,147 patients with suspected malaria were studied in different months across the period 2007-2009. Plasmodium falciparum dhfr and dhps mutations and P. vivax dhfr polymorphisms associated with resistance to SP, as well as P. falciparum pfcrt and pfmdr1 mutations conferring chloroquine resistance, were assessed.PCR-based diagnosis showed that 125 of the 1147 patients had malaria. Of these, 52.8% and 37.6% of cases were due to P. falciparum and P. vivax respectively. A total of 10 cases (8%) showed co-infection by both species and two cases (1.6%) were infected by Plasmodium ovale. Pfdhfr triple mutation and pfdhfr/pfdhps quintuple mutation occurred in 90.8% (95% confidence interval [CI]: 82.2%-95.5%) and 82.9% (95% CI: 72.9%-89.7%) of P. falciparum isolates, respectively. Pfcrt T76 was observed in all cases and pfmdr1 Y86 and pfmdr1 Y1246 in 32.9% (95% CI: 23.4%-44.15%) and 17.1% (95% CI: 10.3-27.1%), respectively. The P. vivax dhfr core mutations, N117 and R58, were present in 98.2% (95% CI: 89.4-99.9%) and 91.2% (95% CI: 80.0-96.7%), respectively.Current molecular data show an extraordinarily high frequency of drug-resistance mutations in both P. falciparum and P. vivax in southern Ethiopia. Urgent surveillance of the emergence and spread of resistance is thus called for. The level of resistance indicates the need for implementation of entire population access to the new first-line treatment with artemether-lumefantrine, accompanied by government monitoring to prevent the emergence of resistance to this treatment.Malaria is the vector-borne disease with the highest impact on the world's human population. In 2008, there were an estimated 243 million cases, leading to nearly 863,000 malaria-related deaths [1]. Although malaria-endemic areas are mainly restricted to tropical and subtropical regions at present, several models nonetheless project the geographical expansion of potential malaria transmission over the next few decades, along with more substanti
Genetic population structure of Anopheles gambiae in Equatorial Guinea
Marta Moreno, Patricia Salgueiro, José Vicente, Jorge Cano, Pedro J Berzosa, Aida de Lucio, Frederic Simard, Adalgisa Caccone, Virgilio E Do Rosario, Jo?o Pinto, Agustín Benito
Malaria Journal , 2007, DOI: 10.1186/1475-2875-6-137
Abstract: Genotyping of 11 microsatellite loci located in chromosome 3 was performed in three island samples (two in Bioko and one in Annobón) and three mainland samples (two in EG and one in Gabon). Four samples belonged to the M molecular form and two to the S-form. Microsatellite data was used to estimate genetic diversity parameters, perform demographic equilibrium tests and analyse population differentiation.High levels of genetic differentiation were found between the more geographically remote island of Annobón and the continent, contrasting with the shallow differentiation between Bioko island, closest to mainland, and continental localities. In Bioko, differentiation between M and S forms was higher than that observed between island and mainland samples of the same molecular form.The observed patterns of population structure seem to be governed by the presence of both physical (the ocean) and biological (the M-S form discontinuity) barriers to gene flow. The significant degree of genetic isolation between M and S forms detected by microsatellite loci located outside the "genomic islands" of speciation identified in A. gambiae s.s. further supports the hypothesis of on-going incipient speciation within this species. The implications of these findings regarding vector control strategies are discussed.Malaria is an infectious disease that causes between 300–500 million annual clinical cases and 1.5–3 million deaths per year, mainly in children under five years old in sub-Saharan Africa [1]. Classical strategies of vector control developed in endemic areas of Africa, such as impregnated bed nets or indoor residual spraying, have not been as effective as expected, and malaria incidence is increasing. Among the factors involved in this failure are the lack of sustainability of vector control programmes and the emergence of insecticide resistance in mosquitoes [2].Genetically based methods have been proposed for malaria vector control. These methods focus mainly in altering
Transmission of malaria and genotypic variability of Plasmodium falciparum on the Island of Annobon (Equatorial Guinea)
Jorge Cano, Pedro Berzosa, Aida de Lucio, Miguel Descalzo, Leonardo Bobuakasi, Sisinio Nzambo, Melchor Ondo, Jesus N Buatiche, Gloria Nseng, Agustin Benito
Malaria Journal , 2007, DOI: 10.1186/1475-2875-6-141
Abstract: A blood sample was taken from the selected children in order to determine Plasmodium infection by microscopical examination and by semi-nested multiplex PCR. The diversity of P. falciparum circulating alleles was studied on the basis of the genes encoding for the merozoite surface proteins, MSP-1 and MSP-2 of P. falciparum.The crude parasite rate was 17% during the dry season and 60% during the rainy season. The percentage of children sleeping under a bed net was over 80% in the two surveys. During the rainy season, 33.3% of the children surveyed were anaemic at the time of the study. No association was found between the crude parasite rate, the use of bed nets and gender, and anaemia. However, children between five and nine years of age were five times less at risk of being anaemic than those aged less than one year. A total of 28 populations of the three allelic families of the msp-1 gene were identified and 39 of the msp-2 gene. The variability of circulating allelic populations is significantly higher in the rainy than in the dry season, although the multiplicity of infections is similar in both, 2.2 and 1.9 respectively.Based on the high degree of geographical isolation of the Annobon population and the apparent marked seasonality of the transmission, it is feasible to believe that malaria can be well controlled from this small African island.Plasmodium falciparum is a highly polymorphic parasite with a high antigens heterogeneity [1]. This heterogeneity may represent a major obstacle to the development of an effective vaccine [2].In general, the P. falciparum infections include a complex mixture of biologically and genetically different populations, as has been demonstrated by different techniques, including the Restriction Fragment Length Polymorphism (RFLP) [3] and the Polymerase Chain Reaction (PCR) [4]. PCR has been used to study the existing polymorphisms in various markers, such as the Merozoite Surface Proteins 1 (MSP-1) and 2 (MSP-2), the circumsporozo
Efficacy of Artesunate + Sulphadoxine-Pyrimethamine (AS?+?SP) and Amodiaquine + Sulphadoxine-Pyrimethamine (AQ?+?SP) for Uncomplicated falciparum Malaria in Equatorial Guinea (Central Africa)
Pilar Charle,Pedro Berzosa,Miguel Angel Descalzo,Aida de Lucio,Jose Raso,Jacqueline Obono,Magdalena Lwanga,Natividad Nlang,Araceli Nchama,Catalina Mangue,Anastasio Micha,Natividad Nsee,Rosario Mesie,Agustín Benito,Jesús Roche
Journal of Tropical Medicine , 2009, DOI: 10.1155/2009/781865
Abstract: Objectives. The objectives of the study were (i) to evaluate the efficacy of combination drugs, such as artesunate
La importancia de los mecanismos de coordinación organizativa en la excelencia del sistema espa ol de trasplantes The importance of the mechanisms for the organizational coordination in the Excellence of the Spanish Transplant System The importance of the mechanisms for the organizational coordination in the excellence of the Spanish transplant system
Carmen De Pablos Heredero,David Lopez Berzosa
Intangible Capital , 2012, DOI: 10.3926/ic.270
Abstract: Purpose:To analyze from an organizational perspective the main critical success factors in the National Transplant System. Design/methodology: Deep interviews with different managerial positions at the system, the National Transplant Organization, coordination units at hospitals and local coordination authorities. Findings: Description of the National Transplant System from a process orientation and analysis of the critical key coordination factors in the final success. Research limitations/implications:Difficult access to quantitative data. Practical implications:The knowledge and spread of the managerial factors that make of the Spanish National Transplant System a worldwide reference. Social implications:To identify and explain a managerial system of excellence that can be an example for other contexts, countries, regions, social realities, etc. Originality/value:To show the success of the system from the organizational perspective. Objeto: Analizar desde una perspectiva organizativa los factores de éxito del Sistema Nacional de Trasplantes Dise o/metodología/enfoque: Entrevista en profundidad a los gestores del sistema, Organización Nacional de Trasplantes, unidades de Coordinación hospitalarias y responsables de coordinación autonómicos. Aportaciones y resultados: Descripción del Sistema Nacional de Trasplantes desde una orientación de procesos y análisis de los factores de coordinación críticos de éxito en su funcionamiento. Limitaciones / implicaciones: Dificultad de acceso a datos cuantitativos. Implicaciones prácticas: conocimiento y difusión de los factores de gestión que hacen del Sistema Nacional de Trasplantes un referente mundial. Implicaciones sociales: reconocimiento de un sistema de gestión de excelencia que puede servir de ejemplo para otros contextos, países, regiones, realidades sociales, etc. Originalidad / Valor a adido: Mostrar el éxito del sistema desde la perspectiva organizativa. Purpose: To analyze from an organizational perspective the main critical success factors in the National Transplant System. Design/methodology: Deep interviews with different managerial positions at the system, the National Transplant Organization, coordination units at hospitals and local coordination authorities. Findings: Description of the National Transplant System from a process orientation and analysis of the critical key coordination factors in the final success. Research limitations/implications: Difficult access to quantitative data. Practical implications: The knowledge and spread of the managerial factors that make of the Spanish National T
Geographic Structuring of the Plasmodium falciparum Sarco(endo)plasmic Reticulum Ca2+ ATPase (PfSERCA) Gene Diversity
Ronan Jambou,Axel Martinelli,Jo?o Pinto,Simonetta Gribaldo,Eric Legrand,Makhtar Niang,Nimol Kim,Lim Pharath,Béatrice Volnay,Marie Therese Ekala,Christiane Bouchier,Thierry Fandeur,Pedro Berzosa,Agustin Benito,Isabel Dinis Ferreira,Cynthia Ferreira,Pedro Paulo Vieira,Maria das Gra?as Alecrim,Odile Mercereau-Puijalon,Pedro Cravo
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009424
Abstract: Artemisinin, a thapsigargin-like sesquiterpene has been shown to inhibit the Plasmodium falciparum sarco/endoplasmic reticulum calcium-ATPase PfSERCA. To collect baseline pfserca sequence information before field deployment of Artemisinin-based Combination therapies that may select mutant parasites, we conducted a sequence analysis of 100 isolates from multiple sites in Africa, Asia and South America. Coding sequence diversity was large, with 29 mutated codons, including 32 SNPs (average of one SNP/115 bp), of which 19 were novel mutations. Most SNP detected in this study were clustered within a region in the cytosolic head of the protein. The PfSERCA functional domains were very well conserved, with non synonymous mutations located outside the functional domains, except for the S769N mutation associated in French Guiana with elevated IC50 for artemether. The S769N mutation is located close to the hinge of the headpiece, which in other species modulates calcium affinity and in consequence efficacy of inhibitors, possibly linking calcium homeostasis to drug resistance. Genetic diversity was highest in Senegal, Brazil and French Guiana, and few mutations were identified in Asia. Population genetic analysis was conducted for a partial fragment of the gene encompassing nucleotide coordinates 87-2862 (unambiguous sequence available for 96 isolates). This supported a geographic clustering, with a separation between Old and New World samples and one dominant ancestral haplotype. Genetic drift alone cannot explain the observed polymorphism, suggesting that other evolutionary mechanisms are operating. One possible contributor could be the frequency of haemoglobinopathies that are associated with calcium dysregulation in the erythrocyte.
Tumbas inéditas de la necrópolis de Osma (Soria) en el Museo del Ejército
De La Torre Echávarri, José Ignacio,Berzosa Del Campo, Ricardo
Gladius , 2002, DOI: 10.3989/gladius.2002.58
Abstract: The basic aims of this work is the study of six panoplies from cemetery of Vi as de Portuguí (Osma, Soria), which were acquired by the Infantry Museum (ancestor of the Army Museum of Madrid) in 1916. This set was constituted by several samples of Celtiberian warriors weapons. We also shall attempt to study an ensemble of objects with Roman influences. These items allow to explain the Roman acculturation process lived by the Uxama population, with the introduction of new materials in the burials En el presente trabajo pretendemos dar a conocer cinco ajuares funerarios procedentes de la necrópolis de Vi as de Portuguí (Osma, Soria), que ingresaron en el antiguo Museo de Infantería en 1916, y que forman parte actualmente de la colección del Museo del Ejército. El lote está formado por un buen número de armas, destacando las características espadas de antenas atrofiadas, así como elementos de clara raigambre cultural romana. Estos nuevos ajuares permitirán ofrecer una visión de conjunto más completa del cementerio, así como acercarnos al proceso de romanización que sufrió la población de Uxama.
Page 1 /15507
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.