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Julián David Salazar-Gutiérrez,Andrés Castelblanco,María Ximena Rodríguez-Bocanegrab,Wilson Teran,Adriana Sáenz-Aponte 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.4
Entomopathogenic nematodes are key players for insect pest control and constitute an environmentally friendly alternative for crop protection. The insecticidal activity of the family Heterorhabditidae relies on a tight symbiotic relationship with enterobacteria of the genus Photorhabdus, where the bacterial contribution towards the death of the host has been highlighted. In the present work, we report the identification and pathogenic characterization of Photorhabdus luminescens strain SL0708, which is the natural symbiont of Heterorhabditis indica SL0708. We evaluated the pathogenicity of whole bacterial cells and acellular extracts against both Spodoptera frugiperda larvae and Galleria mellonella. Phylogenetic analyses using a polygenic sequencing approach assigned the bacterial strain to Photorhabdus luminescens subsp. akhurstii and bioassays showed it is highly pathogenic for both insects. After 48 h of treatment with 1× 103 −1 × 104 CFU/larva, 100% mortality was attained. Furthermore, when intra- or extracellular bacterial extracts were injected into G. mellonella, a cumulative percent mortality of 63% and 100% was respectively obtained after 72 h. In contrast, a 10% and 93% mortality was achieved for S. frugiperda with intra and extracellular extracts, respectively highlighting the role of extracellular factors in pathogenicity. We detected extracellular activities potentially accounting for the high pathogenicity observed and these included; proteases, esterases, ureases, hemolysins and siderophores. Interestingly, S. frugiperda was more susceptible to P. luminescens SL0708 cells than G. mellonella, which contrasted to its higher resistance to H. indica SL0708 nematodes, which suggests that EPN biological control potential should also be evaluated based on bacterial symbiont pathogenicity
Refining drug administration in a murine model of acute infection with Trypanosoma cruzi
Julián Ernesto Nicolás Gulin,Margarita Bisio,Facundo García-Bournissen 한국실험동물학회 2020 Laboratory Animal Research Vol.36 No.4
Background: In animal research, “refinement” refers to modifications of husbandry or experimental procedures to enhance animal well-being and minimize or eliminate pain and distress. Evaluation of drug efficacy in mice models, such as those used to study Trypanosoma cruzi infection, require prolonged drug administration by the oral route (e.g. for 20 consecutive days). However, the orogastric gavage method can lead to significant discomfort, upper digestive or respiratory tract lesions, aspiration pneumonia and even accidental death. The aim of this work was to evaluate the effect of two administration methods (conventional oral gavage vs. a refined method using a disposable tip and automatic pipette) on the efficacy of benznidazole in a murine model of T. cruzi infection. Results: Both administration methods led to a rapid and persistent reduction in parasitaemia. Absence of T. cruzi DNA (evaluated by real-time PCR) in blood, cardiac and skeletal muscle confirmed that treatment efficacy was not influenced by the administration method used. Conclusions: The proposed refined method for long-term oral drug administration may be a suitable strategy for assessing drug efficacy in mice models of Chagas disease and can be applied to similar murine infection models to reduce animal discomfort.
Angel Cuenca,Julián Salt,Vicente Casanova,Ricardo Pizá 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.2
This paper presents a control strategy to face time-varying delays induced in a Networked Control System (NCS). The delay is divided into two parts: the largest one (an integer multiple of the bus cycle) is compensated by means of an adaptive multi-rate Smith predictor, and the smallest one (whose value is strictly smaller than the bus cycle) via a gain scheduling approach based on root locus contour and linearization techniques. The gains to be scheduled belong to a multi-rate PID controller. Control system stability is studied by means of Lyapunov theory. Simulation results and the implementation on a test-bed Profibus-DP environment illustrate that this control structure can maintain NCS performance and stability, despite the considered delays.
Ricardo Gabriel Martínez,Julián Gabriel Leone,Juan Manuel Rodriguez Repeti 부산외국어대학교 중남미지역원 2021 이베로아메리카 Vol.23 No.2
The covid 19 pandemic led to an economic collapse and multiple impacts upon Argentina's labour dynamics. As well as in other parts of the region, falls in employment rates (both due to an increase in unemployment and significant withdrawals from the labour force) were combined with wage reductions for those who were able to keep their jobs. Thus, two important processes for the labour market complimented each other: a structural shock associated with a tasks automation as a reorganisation and substitution of factors, with a cyclical recession caused by the pandemic. The international experience shows the amplifying impact the latter has on the former, generating long-term consequences mainly in routine-intensive jobs. However, the knowledge-intensive services sector appears to be the most capable of cushioning the recessionary shock (both in terms of wages and labour absorption), even with nuances within the sector depending on the extent of the shutdown measures and its capability to switch to remote work. Finally, the task approach is decisive in capturing the ability to adapt both the cyclical and structural processes, absorbing a large part of the explanatory potential that sectoral classifications tend to bring about.
A Non-Uniform Predictor-Observer for a Networked Control System
Angel Cuenca,Pedro García,Pedro Albertos,Julián Salt 제어·로봇·시스템학회 2011 International Journal of Control, Automation, and Vol.9 No.6
This paper presents a Non-Uniform Predictor-Observer (NUPO) based control approach in order to deal with two of the main problems related to Networked Control Systems (NCS) or Sensor Networks (SN): time-varying delays and packet loss. In addition, if these delays are longer than the sampling period, the packet disordering phenomenon can appear. Due to these issues, a (scarce) non-uniform, delayed measurement signal could be received by the controller. But including the NUPO proposal in the control system, the delay will be compensated by the prediction stage, and the non-available data will be reconstructed by the observer stage. So, a delay-free, uniformly sampled controller design can be adopted. To ensure stability, the predictor must satisfy a feasibility problem based on a time-varying delay-dependent condition expressed in terms of Linear Matrix Inequalities (LMI). Some aspects like the relation between network delay and robustness/performance trade-off are empirically studied. A simulation example shows the benefits (robustness and control performance improvement) of the NU-PO approach by comparison to another similar proposal.
Catalina Quintero-Quiroz,Natalia Acevedo,Jenniffer Zapata-Giraldo,Luz E. Botero,Julián Quintero,Diana Zárate-Triviño,Jorge Saldarriaga,Vera Z. Pérez 한국생체재료학회 2020 생체재료학회지 Vol.24 No.1
Background: Chemical reduction has become an accessible and useful alternative to obtain silver nanoparticles (AgNPs). However, its toxicity capacity depends on multiple variables that generate differences in the ability to inhibit the growth of microorganisms. Thus, optimazing parameters for the synthesis of AgNPs can increase its antimicrobial capacity by improving its physical-chemical properties. Methods: In this study a Face Centered Central Composite Design (FCCCD) was carried out with four parameters: AgNO3 concentration, sodium citrate (TSC) concentration, NaBH4 concentration and the pH of the reaction with the objective of inhibit the growth of microorganisms. The response variables were the average size of AgNPs, the peak with the greatest intensity in the size distribution, the polydispersity of the nanoparticle size and the yield of the process. AgNPs obtained from the optimization were characterized physically and chemically. The antimicrobial activity of optimized AgNPs was evaluated against Staphylococcus aureus, Escherichia coli, Escherichia coli AmpC resistant, and Candida albicans and compared with AgNPs before optimization. In addition, the cytotoxicity of the optimized AgNPs was evaluated by the colorimetric assay MTT (3- (4,5- Dimethylthiazol- 2- yl)- 2, 5 - Diphenyltetrazolium Bromide). Results: It was found that the four factors studied were significant for the response variables, and a significant model (p <0.05) was obtained for each variable. The optimal conditions were 8 for pH and 0.01 M, 0.0 6M, 0.01 M for the concentration of TSC, AgNO3, and NaBH4, respectively. Optimized AgNPs spherical and hemispherical were obtained, and 67.66% of it had a diameter less than 10.30 nm. A minimum bactericidal concentration (MBC) and minimum fungicidal Concentration (MFC) of optimized AgNPs was found against Staphylococcus aureus, Escherichia coli, Escherichia coli AmpC resistant, and Candida albicans at 19.89, 9.94, 9.94, 2.08 μg/mL, respectively. Furthermore, the lethal concentration 50 (LC50) of optimized AgNPs was found on 19.11 μg/mL and 19.60 μg/mL to Vero and NiH3T3 cells, respectively. Conclusions: It was found that the factors studied were significant for the variable responses and the optimization process used was effective to improve the antimicrobial activity of the AgNPs.