Papers by Manuel Antonio Veloza Lopez
Physics Procedia, 2011
In this work, poly(lactic-co-glycolic acid) (PLGA) and chitosan (CS) nanoparticles were synthesiz... more In this work, poly(lactic-co-glycolic acid) (PLGA) and chitosan (CS) nanoparticles were synthesized with the purpose of encapsulating levofloxacin (LEV). A thorough study has been carried out in order to optimize the preparation of LEV-loaded polymeric nanoparticles (NPs) suitable for parenteral administration. Changes in the preparation method, in the organic solvent nature, in the pH of the aqueous phase, or in the temperature were investigated. To the authors´knowledge, a systematic study in order to improve the LEV nanocarrier characteristics and the yield of drug encapsulation has not been carried out to date. The physicochemical characterization of the NPs, their encapsulation efficiency (EE), and the in vitro release of LEV revealed that the best formulation was the emulsion-solvent evaporation method using dichloromethane as organic solvent, which renders suitable LEV loaded PLGA NPs. The morphology of these NPs was investigated using TEM. Their antimicrobial activities against several microorganisms were determined in vitro measuring the minimum inhibitory concentration (MIC). The results show that the use of these loaded LEV PLGA nanoparticles has the advantage of the slow release of the antibiotic, which would permit an increase in the time period between administrations as well as to decrease the side effects of the drug.
Journal of Photochemistry and Photobiology A: Chemistry, 2014
Chemical reactivity under restricted geometry conditions can be described through the equations o... more Chemical reactivity under restricted geometry conditions can be described through the equations of the Pseudophase Model (a two state model). This model is based on the assumption of an equilibrium between these two states (free and bound) which is not perturbed by the reactive event. This implies that the reaction in which these states participate must be slow, in relation to the exchange processes between the two states. This condition holds in the case of chemical reactions, but does not hold for very rapid photochemical reactions. However, the Pseudophase Model seems to be applicable, apparently, in the case of excited state reactions. According to this a similar formal behavior is observed in chemical and photochemical reactions. However, a closer inspection of the data reveals important differences between the two types of reactions, in particular in the meaning of the parameters appearing in the equations of the Pseudophase Model. These similarities, and differences, are considered in this work using, as representative examples, the reactions between [Fe(CN) 5 (4-CNpy)] 3− and [Co(NH 3) 4 (pzCO 2)] 2+ (chemical) and the quenching of pyrene by the iodide ion (photochemical), under restricted geometry conditions. These conditions are due to the presence of receptors (CTACl micelles and DNA, respectively) in the reaction media. An explanation for these facts is given.
IEEE Transactions on Multimedia, 2000
This paper describes and analyzes JPIP-W, an innovative proposal for the interactive transmission... more This paper describes and analyzes JPIP-W, an innovative proposal for the interactive transmission of JPEG2000 images on the Internet. JPIP-W is an extension of JPIP, the current JPEG protocol proposed for interactive JPEG2000 image browsing. One of the JPIP characteristics of greatest interest is its ability to use the Web for retrieving images. However, JPIP is unable to exploit the large infrastructure of today's Web caching systems (proxies), used to reduce response time and network traffic. To overcome this drawback, JPIP-W defines a new server-client interaction consisting of splitting JPEG2000 images into data blocks that can be cached by the proxies. These blocks can be shared among several clients, allowing fast recovery of some portions of the images. Experimental results demonstrate that JPIP-W significantly reduces JPIP retrieving times.
Continental Shelf Research, 2006
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AIDS Research and Human Retroviruses, 2008
The aim of this study was to evaluate the long-term efficacy and safety of didadosine (ddI), lami... more The aim of this study was to evaluate the long-term efficacy and safety of didadosine (ddI), lamivudine (3TC), and efavirenz (EFV). This was a follow-up to the VESD study, a 12-month open-label, observational, multicenter study of adult patients with HIV infection who started antiretroviral treatment with the ddI-3TC-EFV once-daily regimen. Of the 167 patients originally included, 106 patients remained on the same triple therapy at the end of the study (1 year), and they were offered an extra 24 months of follow-up; 96 were enrolled in this study (VESD-2). Seventy patients out of the initial cohort were still on the same regimen at month 36, with 97% of them with plasma viral load Ͻ50 copies /ml. An intention-to-treat analysis showed that the percentage of patients with plasma viral load Ͻ50 copies/ml was 73% at 36 months. CD4 cell counts increased 344 cells/l over the 36 months. Safety and tolerance were good with no unexpected long-term toxicity. After 3 years of treatment with ddI-3TC-EFV, more than 40% of the patients were still receiving the initial antiretroviral therapy with sustained, durable immunovirological benefit and good acceptance. Long-term toxicity and virological failure were low.
RESUMEN: El objetivo de este trabajo es identificar las prácticas de un buen liderazgo en las PYM... more RESUMEN: El objetivo de este trabajo es identificar las prácticas de un buen liderazgo en las PYME comerciales de Machala, Ecuador, que generan buenos resultados, y conllevan al cumplimiento de la misión y visión de la empresa. Se aplicó un cuestionario a 255 gerentes de las organizaciones. En base a los resultados se identificaron las cinco dimensiones del Inventario de Prácticas de Liderazgo: desafiar los procesos, inspirar una visión compartida, habilitar a los demás para actuar, modelar el camino y dar aliento al corazón, presentes en las prácticas de liderazgo de la gerencia comercial de las empresas analizadas, en Machala, Ecuador. Palabras-Clave: Liderazgo, empresa, misión, visión ABSTRACT: The objective of this work is to identify good leadership practices in commercial SMEs, in Machala, Ecuador, which generate good results, and lead to the fulfillment of the mission and vision of the company. A questionnaire was applied to 255 managers of the organizations. Based on the res...
2005 Purtuguese Conference on Artificial Intelligence, 2005
Acta Otorrinolaringologica (English Edition), 2007
Journal of the American Society of Nephrology, 2004
Patients returning to hemodialysis (HD) after failure of their kidney transplant suffer from high... more Patients returning to hemodialysis (HD) after failure of their kidney transplant suffer from high morbidity and mortality rates. It is common practice to keep failed kidney transplants in place. It is not known if these failed kidney transplants induce an inflammatory state that contributes to morbidity and mortality. In a single facility, patients starting on HD with failed kidney transplant were identified (Group A) and screened for the presence of chronic inflammatory state. Those with clinical symptoms attributed to the failed allograft (Group A1) were not offered transplant nephrectomy unless deemed necessary during follow-up. Their clinical and laboratory data were followed up for 6 months. Similar data were obtained from a group of incident HD patients (Group B). Forty-three patients had a failed Kidney transplant (Group A). Of these, 29 comprised Group A1 and 14 Group A2. Group B comprised 121 patients. In comparison with Group B, Group A exhibited worse anemia and erythropoietin resistance index (ERI), had lower serum albumin and prealbumin, and higher CRP. Group A1 had lower Hb and higher ferritin, CRP, and ESR in comparison with Group A2. Following transplant nephrectomy, Group A1 had improvement in ERI, serum albumin, prealbumin, ferritin, fibrnogen, CRP, and ESR. At 6 months, Group A1 had higher Hb and serum albumin levels, and lower CRP and ERI in comparison with Group A2. Group B parameters showed no change during follow-up. Patients returning to HD following failure of their kidney transplant suffer from a chronic inflammatory state. Resection of failed transplants in symptomatic patients is associated with amelioration of markers of chronic inflammation. Transplant nephrectomy should be considered a treatment option for patients with failed kidney transplants, especially if they exhibit signs and symptoms of chronic inflammatory state.
Infection and Immunity, 2001
Murine immunization with Trypanosoma cruzi KMP11-HSP70fused genes but not the KMP11 gene alone el... more Murine immunization with Trypanosoma cruzi KMP11-HSP70fused genes but not the KMP11 gene alone elicited both an immunoglobulin G2a long-lasting humoral immune response against KMP11 protein and activation of CD8+ cytotoxic T lymphocytes specific for two KMP11 peptides containing A2 motifs. Moreover, protection against the parasite challenge was observed after immunization with the chimeric gene.
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Papers by Manuel Antonio Veloza Lopez