2.1 Estudios de doctorado y postdoctorado

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https://hdl.handle.net/20.500.12390/329

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Now showing 1 - 5 of 338
  • Publication
    Evaluation of the antioxidant activities of aqueous extracts from seven wild plants from the Andes using an in vivo yeast assay
    (Elsevier B.V., 2021-01-01)
    Gonzales, Miki
    ;
    Villena, Gretty K.
    ;
    Kitazono, Ana A.
    The antioxidant activities of the aqueous extracts of seven wild plants were investigated, using both in vitro and in vivo assays. The former relied on the use of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the latter, on the sensibility towards hydrogen peroxide of the yeast sod1 mutant. The studied plants were all wild, collected at the Ccamarrara hill (4000 m.a.s.l. Cusco, Peru), and of the following species: Plantago australis, Baccharis latifolia, Ageratina sternbergiana, Stevia macbridei, Ageratina cuzcoensis, Calceolaria myriophylla, and Adiantum orbignyanum. The DPPH assay demonstrated high antioxidant contents in the dry leaves of all tested plants, with AAEAC values (ascorbic acid equivalent antioxidant capacity) ranging from 20.6 to 72.7 mg/g dry leaves. The antioxidant activities were also evident in the yeast assay, which also allowed distinction between the intracellular and extracellular effects. These in vitro and in vivo studies demonstrate the need to further investigate native wild plants from the Andes as important sources for water-soluble antioxidant compounds. © 2021 The Authors
  • Publication
    Draft genome sequences of enterohemorrhagic and enteropathogenic Escherichia coli strains isolated from alpacas in Peru
    (American Society for Microbiology, 2018-01-01)
    Maturrano L.
    ;
    Aleman M.
    ;
    Carhuaricra D.
    ;
    Maximiliano J.
    ;
    Siuce J.
    ;
    Luna L.
    ;
    Rosadio R.
    The draft genome sequences of two strains of Escherichia coli, isolated from alpacas in Peru, are reported here. ECA1 has been determined to be a strain of enterohemorrhagic E. coli and ECB1 a strain of enteropathogenic E. coli. These pathogens are responsible for hemolytic-uremic syndrome in humans and diarrhea in different mammals, respectively.
  • Publication
    Design of a "test Cell" to be located at 4500 masl in a high Andean region of Peru and dynamic simulation of the thermal performance of housing wall materials
    (Institute of Physics Publishing, 2020-01-01)
    Molina J.O.
    ;
    Horn M.J.
    ;
    Gómez M.M.
    The objective of the present study is to select appropriate wall materials for houses in high Andean regions based on the measurements of the thermal behavior of construction materials using a "Test Cell" under real environmental conditions. It will be the first "Test Cell" to be installed in Peru, in Imata-Arequipa, at 4500 masl. The design and thermal analysis of the "Test Cell" are presented using dynamic simulations with the EnergyPlus program. Initially, the thermal performance of adobe, a traditional construction material in rural regions of Peru, is simulated using real meteorological data recorded in Imata between August 18 and 24, 2018, a period with low temperatures (-12.6 °C). © Published under licence by IOP Publishing Ltd.
  • Publication
    Wind Speed Measurement Method Using Ultrasonic Sensors with Stationary Wavelet Transform
    (IEEE, 2012-01-01)
    Ingaroca, NSC
    ;
    Villanueva, JMM
    ;
    Freire, RCS
    ;
    Catunda, SYC
    A method for measuring speed wind, based on echo detection using ultrasonic transducers with stationary wavelet transform is presented. The stationary wavelet transform (SWT) can be obtained by modifying the basic scheme of discrete wavelet transform (DWT). Two filters are applied to produce the output two sequences at each level. Since decimation is not obtained at the exit of each level, sequences of length equal to the original signal. But the filters are changed at each level adding zeros. After obtaining the SWT coefficients, noise removal will be performed using the soft-threshold rule due the coefficients still include the effects of noise. The measured ultrasound signals are processed using the stationary wavelet transform. The accuracy of the extracted information from the processed signal depends on the adopted mother wavelet. To select the best mother wavelet for signal processing, a criterion based on Shannon's entropy is used. The influence of uncertainties associated with additive noise and attenuation of the ultrasonic signal on the wind speed measurement uncertainty is analyzed.
  • Publication
    The immunoglobulin M-Shed acute phase antigen (SAPA)-test for the early diagnosis of congenital Chagas disease in the time of the elimination goal of mother-to-child transmission
    (Oxford University Press, 2021-01-01)
    Castro-Sesquen Y.E.
    ;
    Tinajeros F.
    ;
    Bern C.
    ;
    Galdos-Cardenas G.
    ;
    Malaga E.S.
    ;
    Valencia Ayala E.
    ;
    Hjerrild K.
    ;
    Clipman S.J.
    ;
    Lescano A.G.
    ;
    Bayangos T.
    ;
    Castillo W.
    ;
    Menduiña M.C.
    ;
    Talaat K.R.
    ;
    Gilman R.H.
    ;
    Verastegui M.
    ;
    Calderon M.
    ;
    Chávez C.
    ;
    Leigue J.K.
    ;
    Hinojosa E.
    ;
    Urquizu F.
    ;
    Gorena M.
    ;
    Serrudo V.
    ;
    Cabrera L.
    ;
    Romero Y.K.
    ;
    Chagas Working Group in Bolivia and Peru
    Background: Diagnosis of congenital Chagas disease (CChD) in most endemic areas is based on low-sensitive microscopy at birth and 9-month immunoglobulin G (IgG), which has poor adherence. We aim to evaluate the accuracy of the Immunoglobulin M (IgM)-Shed Acute Phase Antigen (SAPA) test in the diagnosis of CChD at birth. Methods: Two cohort studies (training and validation cohorts) were conducted in 3 hospitals in the department of Santa Cruz, Bolivia. Pregnant women were screened for Chagas disease, and all infants born to seropositive mothers were followed for up to 9 months to diagnose CChD. A composite reference standard was used to determine congenital infection and was based on the parallel use of microscopy, quantitative polymerase chain reaction (qPCR), and IgM-trypomastigote excreted-secreted antigen (TESA) blot at birth and/or 1 month, and/or the detection of anti-Trypanosoma cruzi IgG at 6 or 9 months. The diagnostic accuracy of the IgM-SAPA test was calculated at birth against the composite reference standard. Results: Adherence to the 6- or 9-month follow-up ranged from 25.3% to 59.7%. Most cases of CChD (training and validation cohort: 76.5% and 83.7%, respectively) were detected during the first month of life using the combination of microscopy, qPCR, and/or IgM-TESA blot. Results from the validation cohort showed that when only 1 infant sample obtained at birth was evaluated, the qPCR and the IgM-SAPA test have similar accuracy (sensitivity: range, 79.1%-97.1% and 76.7%-94.3%, respectively, and specificity: 99.5% and 92.6%, respectively). Conclusions: The IgM-SAPA test has the potential to be implemented as an early diagnostic tool in areas that currently rely only on microscopy. © 2020 The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved.