3.2 Pasantías y ponencias
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PublicaciónDetermination of the Absolute Configuration of 19-OH-(-)-eburnamonine Using a Combination of Residual Dipolar Couplings, DFT Chemical Shift Predictions, and Chiroptics(SAGE Publications Inc., 2012)19-OH-(-)-eburnamonine 1 is a new indole alkaloid isolated from Bonafusia macrocalyx. A natural derivative from (-)-eburnamonine for which absolute configuration and conformation has been determined by making use of residual dipolar couplings enhanced NMR, circular dichroism spectra and high-level computations.
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PublicaciónInfluence of pyrolytic seeds on ZnO nanorod growth onto rigid substrates for photocatalytic abatement of Escherichia coli in water(IWA Publishing, 2014)ZnO nanorods (ZnO NRs) were grown on ZnO seeded fluorine doped tin oxide (FTO) substrates at low temperatures (90 W C) from Zn2þ precursors in alkaline aqueous solution. The ZnO seeds were deposited on the FTO substrate heated at 350 W C by spray pyrolysis of a zinc acetate solution in a water ethanol mixture. The structure of seeds was tuned by the ethanol water ratio, Γ, which controls the solvent evaporation rate of drops impinging the substrate. The relationship between the microstructure and optical properties of the ZnO NR films and the photocatalytic antibacterial activity for Escherichia coli abatement, was determined through a detailed characterization of the material. The higher photocatalytic antibacterial activity was performed by ZnO NR films grown on seeds deposited from solutions with Γ in the 0.0–0.03 range. With these films, the population of viable E. coli dropped more than six orders, from 8 × 108 to 4 × 102 CFU. These results show the potential of these materials in water disinfection.
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PublicaciónIFN-gamma production in response to Tax 161-233, and frequency of CD4(+) Foxp3(+) and Lin(-) HLA-DRhigh CD123(+) cells, discriminate HAM/TSP patients from asymptomatic HTLV-1-carriers in a Peruvian population(Wiley-Blackwell Publishing Ltd, 2009)Human T-lymphotropic virus 1 (HTLV-1) can cause HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The objective of this study was to gain insight into the pathogenesis of HAM/TSP by focusing on the CD8(+) T-cell response. Twenty-three HTLV-1-seronegative controls (SC), 29 asymptomatic HTLV-1 carriers (AC) and 48 patients with HAM/TSP were enrolled in the study. We evaluated the production of interferon-gamma (IFN-gamma) in peripheral blood mononuclear cells stimulated with Tax overlapping peptides, the expression of genes related to the CD8(+) cytotoxic T-cell response, the frequency of CD4(+) Foxp3(+) cells and of dendritic cells, and the HTLV-1 provirus load (PVL). The frequency of cells producing IFN-gamma in response to Tax 161-233, but not to Tax 11-19, discriminated patients with HAM/TSP from AC. The increased pro-inflammatory response observed in patients with HAM/TSP was shared by AC with a high PVL, who also exhibited lower levels of granzyme H mRNA in unstimulated CD8(+) T cells than AC with a low PVL. Patients with HAM/TSP showed higher frequencies of CD4(+) Foxp3(+) cells and lower frequencies of plasmacytoid dendritic cells (pDC) than AC. Our findings are consistent with a model in which HTLV-1, along with the host genetic background, drives quantitative and qualitative changes in pDC and CD4(+) Foxp3(+) cells that lead to a predominance of inflammatory responses over lytic responses in the CD8(+) T-cell response of individuals predisposed to develop HAM/TSP.
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PublicaciónThe use of natural product scaffolds as leads in the search for trypanothione reductase inhibitors(Elsevier Ltd, 2008)Twenty-three heterocyclic compounds were evaluated for their potential as trypanothione reductase inhibitors. As a result, the harmaline, 10-thiaisoalloxazine, and aspidospermine frameworks were identified as the basis of inhibitors of Trypanosoma cruzi trypanothione reductase. Two new compounds showed moderately strong, linear competitive inhibition, namely N,N-dimethyl-N-[3-(7-methoxy-1- methyl-3,4-dihydro-9H-b-carbolin-9-yl)propyl]amine (15) and 1,3-bis[3-(dimethylamino)propyl]-1,5- dihydro-2H-pyrimido[4,5-b][1,4]benzothiazine-2,4(3H)-dione (21), with Ki values of 35.1 ± 3.5 lM and 26.9 ±1.9 lM, respectively. Aspidospermine (25) inhibited T. cruzi TryR with a Ki of 64.6 ± 6.2 lM. None of the compounds inhibited glutathione reductase. Their toxicity toward promastigotes of Leishmania amazonensis was assessed.
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PublicaciónArsenic in Peruvian rice cultivated in the major rice growing region of Tumbes river basin(Elsevier Ltd, 2020)Arsenic (As) exposure from surface and groundwater in Peru is being recognised as a potential threat but there are limited studies on As in the food-chain and none on As in Peruvian rice. In this study, we have determined the As content in rice cultivated in the Tumbes river basin located in the northern province of Peru, an area known for extensive rice cultivation. We collected rice and soil samples from agricultural fields, soil was collected using grid sampling technique while rice was collected from the heaps of harvested crop placed across the fields. The average total As concentration in rice was 167.94 ± 71 μg kg−1 (n = 29; range 68.39–345.31 μg kg−1). While the rice As levels were not highly elevated, the As content of few samples (n = 7) greater than 200 μg kg−1 could contribute negatively to human health upon chronic exposure. Average concentration of As in soil was 8.63 ± 7.8 mg kg−1 (n = 30) and soil to grain transfer factor was 0.025 ± 0.018 for 12 matched samples. Compared to our previous pilot study in 2006 (samples collected from the same agricultural fields but not from exact locations) there was a 41% decrease in As soil concentration in this study. Rice samples collected in 2006 (n = 5) had a mean concentration of 420 ± 109 μg kg−1. Our data provides a baseline of rice grain As concentrations in Peruvian province of Tumbes and warrants further studies on factors affecting uptake of As by the rice varieties cultivated in Peru and any potential human health risks. © 2019 Elsevier Ltd
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