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Search Results: 1 - 10 of 32706 matches for " Daniel Ajzenberg "
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Introducción a la hidrogenación de aceite y su implementación en un proceso supercrítico: caso del aceite de girasol
Ajzenberg, Nancy
Grasas y Aceites , 2002,
Abstract: With 25 millions tons per year, the hydrogenated oil production is on the top in the food market. In this review we deal with the sunflower seed oil hydrogenation with special attention to the economy of the product, the reaction kinetic and parameters studies (like reactor, isomers production, catalyst). Furthermore we point out the necessities to use a new process considering ecological, safety and economic requirements. Then, using new catalysts based on Pt (instead of Ni) and a supercritical solvent, the trans isomers level can be reduced. Furthermore, the supercritical technology improves the process regarding reaction rate and solvent treatment. Con 25 millones de toneladas al a o, la producción de aceite hidrogenado tiene su sitio en el mercado de la alimentación. Este artículo trata de la hidrogenación del aceite de girasol pasando por la economía del producto, la cinética de la reacción y el estudio de parámetros (como el reactor, la producción de isómeros, el catalizador) y explícita las necesidades de usar un nuevo proceso para cumplir normas ecológicas, sanitarias y económicas. Así, utilizando nuevos catalizadores de platino (en vez de níquel) y un solvente supercrítico, se baja la cantidad de isómeros trans producidos, que son nefastos para la salud. Además, la tecnología supercrítica mejora el proceso sobre todo del punto de vista de la reacción y del tratamiento del solvente.
Transeuntes América Latina
Ajzenberg Elza
Estudos Avan?ados , 2005,
Abstract:
Caracterización biológica y molecular del aislamiento CIBMUQ/HDC, una cepa colombiana de referencia para Toxoplasma gondii
Gallego,Carolina; Casta?o,Jhon Carlos; Giraldo,Alejandra; Ajzenberg,Daniel; Dardé,Marie-Laure; Gómez,Jorge Enrique;
Biomédica , 2004,
Abstract: there are few reports about characterization strains of toxoplasma gondii that analyze the differences between isolates from europe or united states with those obtained in south america. the current study analyzes virulence data from the mouse model, the gene sag2 polymorphism by pcr-rflp and microsatellite analysis in a single colombian isolate. the strain was isolated from blood of a child with congenital toxoplasmosis, living in armenia, colombia. analysis of virulence in the mouse showed that this strain has an ld 100 of 10 tachyzoites. both methods of genetic characterization demonstrated that this strain belonged to the clonal type 1 and was called hom/ctco/2002/cibmuq/bl/hdc (brief name: cibmuq/hdc). the cibmuq/hdc strain is the first colombian strain available as a reference strain for national and international researchers.
Additional Haplogroups of Toxoplasma gondii out of Africa: Population Structure and Mouse-Virulence of Strains from Gabon
Aurélien Mercier,Sébastien Devillard,Barthélémy Ngoubangoye,Henri Bonnabau,Anne-Laure Ba?uls,Patrick Durand,Bettina Salle,Daniel Ajzenberg,Marie-Laure Dardé
PLOS Neglected Tropical Diseases , 2010, DOI: 10.1371/journal.pntd.0000876
Abstract: Background Toxoplasma gondii is found worldwide, but distribution of its genotypes as well as clinical expression of human toxoplasmosis varies across the continents. Several studies in Europe, North America and South America argued for a role of genotypes in the clinical expression of human toxoplasmosis. Genetic data concerning T. gondii isolates from Africa are scarce and not sufficient to investigate the population structure, a fundamental analysis for a better understanding of distribution, circulation, and transmission. Methodology/Principal Findings Seropositive animals originating from urban and rural areas in Gabon were analyzed for T. gondii isolation and genotyping. Sixty-eight isolates, including one mixed infection (69 strains), were obtained by bioassay in mice. Genotyping was performed using length polymorphism of 13 microsatellite markers located on 10 different chromosomes. Results were analyzed in terms of population structure by Bayesian statistical modeling, Neighbor-joining trees reconstruction based on genetic distances, FST and linkage disequilibrium. A moderate genetic diversity was detected. Three haplogroups and one single genotype clustered 27 genotypes. The majority of strains belonged to one haplogroup corresponding to the worldwide Type III. The remaining strains were distributed into two haplogroups (Africa 1 and 3) and one single genotype. Mouse virulence at isolation was significantly different between haplogroups. Africa 1 haplogroup was the most virulent. Conclusion Africa 1 and 3 haplogroups were proposed as being new major haplogroups of T. gondii circulating in Africa. A possible link with strains circulating in South and Central America is discussed. Analysis of population structure demonstrated a local spread within a rural area and strain circulation between the main cities of the country. This circulation, favored by human activity could lead to genetic exchanges. For the first time, key epidemiological questions were addressed for the West African T. gondii population, using the high discriminatory power of microsatellite markers, thus creating a basis for further epidemiological and clinical investigations.
Narrativa da memória epopéia paulista
Alecsandra M. de Oliveira,Elza Ajzenberg
ARS (S?o Paulo) , 2008, DOI: 10.1590/s1678-53202008000100005
Abstract:
Acute Lung, Heart, Liver, and Pancreatic Involvements with Hyponatremia and Retinochoroiditis in a 33-Year-Old French Guianan Patient
Matthieu Groh ,Alexandra Faussart,Isabelle Villena,Daniel Ajzenberg,Bernard Carme,Magalie Demar,Véronique Joly,Sandrine Houze,Stéphane Simon,Dominique Aubert,Cécile Charlois-Ou,Patrick Yeni
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001802
Abstract:
Transcriptional Analysis of Murine Macrophages Infected with Different Toxoplasma Strains Identifies Novel Regulation of Host Signaling Pathways
Mariane B. Melo,Quynh P. Nguyen,Cynthia Cordeiro,Musa A. Hassan,Ninghan Yang,Renée McKell,Emily E. Rosowski,Lindsay Julien,Vincent Butty,Marie-Laure Dardé,Daniel Ajzenberg,Katherine Fitzgerald,Lucy H. Young,Jeroen P. J. Saeij
PLOS Pathogens , 2013, DOI: 10.1371/journal.ppat.1003779
Abstract: Most isolates of Toxoplasma from Europe and North America fall into one of three genetically distinct clonal lineages, the type I, II and III lineages. However, in South America these strains are rarely isolated and instead a great variety of other strains are found. T. gondii strains differ widely in a number of phenotypes in mice, such as virulence, persistence, oral infectivity, migratory capacity, induction of cytokine expression and modulation of host gene expression. The outcome of toxoplasmosis in patients is also variable and we hypothesize that, besides host and environmental factors, the genotype of the parasite strain plays a major role. The molecular basis for these differences in pathogenesis, especially in strains other than the clonal lineages, remains largely unexplored. Macrophages play an essential role in the early immune response against T. gondii and are also the cell type preferentially infected in vivo. To determine if non-canonical Toxoplasma strains have unique interactions with the host cell, we infected murine macrophages with 29 different Toxoplasma strains, representing global diversity, and used RNA-sequencing to determine host and parasite transcriptomes. We identified large differences between strains in the expression level of known parasite effectors and large chromosomal structural variation in some strains. We also identified novel strain-specifically regulated host pathways, including the regulation of the type I interferon response by some atypical strains. IFNβ production by infected cells was associated with parasite killing, independent of interferon gamma activation, and dependent on endosomal Toll-like receptors in macrophages and the cytoplasmic receptor retinoic acid-inducible gene 1 (RIG-I) in fibroblasts.
Geographic Separation of Domestic and Wild Strains of Toxoplasma gondii in French Guiana Correlates with a Monomorphic Version of Chromosome1a
Asis Khan,Daniel Ajzenberg,Aurélien Mercier,Magalie Demar,Stéphane Simon,Marie Laure Dardé,Qiuling Wang,Shiv Kumar Verma,Benjamin M. Rosenthal,Jitender P. Dubey,L. David Sibley
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0003182
Abstract: Background Previous studies have stressed the genetic divergence and high pathogenicity of strains of T. gondii from French Guiana. Although strains from coastal, human adapted environments (so called anthropized) resemble those found in other regions of the Caribbean, strains collected from inland jungle environment are genetically quite diverse. To better understand the composition of these distinct strain types, we undertook a more in depth analysis of T. gondii strains from French Guiana including profiling of chromosome 1a (Chr1a), which is often shared as a single monomorphic haplotype among lineages that are otherwise genetically distinct. Methodology/Principal Findings Comparison of intron sequences from selectively neutral genes indicated that anthropized strains were most closely related to clonal type III strains from North America, although wider RFLP analysis revealed that they are natural hybrids. In contrast, strains isolated from the jungle were genetically very diverse. Remarkably, nearly all anthropized strains contained the monomorphic version of Chr1a while wild stains were extremely divergent. The presence of the monomorphic Chr1a strongly correlated with greater transmission in domestic cats, although there were several exceptions, indicating that other factors also contribute. Anthropized strains also varied in their virulence in laboratory mice, and this pattern could not be explained by the simple combination of previously identified virulence factors, indicating that other genetic determinants influence pathogenicity. Conclusions/Significance Our studies underscore the marked genetic separation of anthropized and wild strains of T. gondii in French Guiana and provide additional evidence that the presence of Chr1a is associated with successful expansion of widely different lineages within diverse geographic areas. The predominance of Chr1a among strains in the anthropized environment suggests that it may confer an advantage for transmission in this environment, and thus potentially contribute to the spread of pathogenecity determinants.
Severe South American Ocular Toxoplasmosis Is Associated with Decreased Ifn-γ/Il-17a and Increased Il-6/Il-13 Intraocular Levels
Alejandra de-la-Torre,Arnaud Sauer,Alexander W. Pfaff,Tristan Bourcier,Julie Brunet,Claude Speeg-Schatz,Laurent Ballonzoli,Odile Villard,Daniel Ajzenberg,Natarajan Sundar,Michael E. Grigg,Jorge E. Gomez-Marin equal contributor,Ermanno Candolfi equal contributor
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002541
Abstract: In a cross sectional study, 19 French and 23 Colombian cases of confirmed active ocular toxoplasmosis (OT) were evaluated. The objective was to compare clinical, parasitological and immunological responses and relate them to the infecting strains. A complete ocular examination was performed in each patient. The infecting strain was characterized by genotyping when intraocular Toxoplasma DNA was detectable, as well as by peptide-specific serotyping for each patient. To characterize the immune response, we assessed Toxoplasma protein recognition patterns by intraocular antibodies and the intraocular profile of cytokines, chemokines and growth factors. Significant differences were found for size of active lesions, unilateral macular involvement, unilateral visual impairment, vitreous inflammation, synechiae, and vasculitis, with higher values observed throughout for Colombian patients. Multilocus PCR-DNA sequence genotyping was only successful in three Colombian patients revealing one type I and two atypical strains. The Colombian OT patients possessed heterogeneous atypical serotypes whereas the French were uniformly reactive to type II strain peptides. The protein patterns recognized by intraocular antibodies and the cytokine patterns were strikingly different between the two populations. Intraocular IFN-γ and IL-17 expression was lower, while higher levels of IL-13 and IL-6 were detected in aqueous humor of Colombian patients. Our results are consistent with the hypothesis that South American strains may cause more severe OT due to an inhibition of the protective effect of IFN-γ.
Anti-PF4/heparin antibodies associated with repeated hemofiltration-filter clotting: a retrospective study
Sigismond Lasocki, Pascale Piednoir, Nadine Ajzenberg, Arnaud Geffroy, Abdel Benbara, Philippe Montravers
Critical Care , 2008, DOI: 10.1186/cc6937
Abstract: We reviewed the charts of all patients who had an anti-PF4/heparin antibody assay performed for repeated hemofiltration-filter clotting between November 2004 and May 2006 in our surgical intensive care unit. We used an enzyme-linked immunoabsorbent assay (heparin-platelet factor 4-induced antibody) with an optical density (OD) of greater than 1 IU considered positive.During the study period, anti-PF4/heparin antibody assay was performed in 28 out of 87 patients receiving CVVH. Seven patients were positive for anti-PF4/heparin antibodies (OD 2.00 [1.36 to 2.22] IU) and 21 were antibody-negative (OD 0.20 [0.10 to 0.32] IU). Baseline characteristics, platelet counts, and activated partial thromboplastin time ratios were not different between the two groups. CVVH duration was significantly decreased in antibody-positive patients (5.0 [2.5 to 7.5] versus 12.0 [7.5 to 24.0] hours; P = 0.007) as was CVVH efficiency (urea reduction ratio 17% [10% to 37%] versus 44% [30% to 52%]; P = 0.04) on heparin infusion. Anti-PF4/heparin antibody concentration was inversely correlated with CVVH duration. The receiver operating characteristic curve showed that a 6-hour cutoff was the best CVVH session duration to predict a positive antibody test (sensitivity 71%, specificity 85%, and area under the curve 0.83). CVVH duration (32 [22 to 37] hours; P < 0.05) and urea reduction (55% [36% to 68%]; P < 0.03) were restored by danaparoid sodium infusion.Repeated hemofiltration-filter clotting in less than 6 hours was often associated with the presence of anti-PF4/heparin antibodies, regardless of the platelet count. In antibody-positive patients, replacement of heparin by danaparoid sodium allowed the restoration of CVVH duration and efficiency.Heparin-induced thrombocytopenia (HIT) is an antibody-mediated adverse effect of heparin. The initial description concerned arterial thrombosis during unfractionated heparin (UFH) therapy [1]. HIT subsequently has been associated with an increased risk
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