Browsing by Author "Figueroa, David"

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    Mode of action of p-quinone derivatives with trypanocidal activity studied by experimental and in silico models
    (2023) Ballesteros-Casallas, Andres; Quiroga, Cristina; Ortiz, Cecilia; Benitez, Diego; Denis, Pablo A.; Figueroa, David; Salas, Cristian O.; Bertrand, Jeanluc; Tapia, Ricardo A.; Sanchez, Patricio; Miscione, Gian Pietro; Comini, Marcelo A.; Paulino, Margot
    Quinones are attractive pharmacological scaffolds for developing new agents for the treatment of different transmissible and non-transmissible human diseases due to their capacity to alter the cell redox homeostasis.The bioactivity and potential mode of action of 19 p-quinone derivatives fused to different aromatic rings (carbo or heterocycles) and harboring distinct substituents were investigated in infective Trypanosoma brucei brucei. All the compounds, except for a furanequinone (EC50=38 mu M), proved to be similarly or even more potent (EC50 = 0.5-5.5 mu M) than the clinical drug nifurtimox (EC50 = 5.3 mu M). Three furanequinones and one thia-zolequinone displayed a higher selectivity than nifurtimox. Two of these selective hits resulted potent inhibitors of T. cruzi proliferation (EC50=0.8-1.1 mu M) but proved inactive against Leishmania infantum amastigotes.Most of the p-quinones induced a rapid and marked intracellular oxidation in T. b. brucei. DFT calculations on the oxidized quinone (Q), semiquinone (Q center dot-) and hydroquinone (QH2) suggest that all quinones have negative Delta G for the formation of Q center dot-. Qualitative and quantitative structure-activity relationship analyses in two or three dimensions of different electronic and biophysical descriptors of quinones and their corresponding bioactivities (killing potency and oxidative capacity) were performed.Charge distribution over the quinone ring carbons of Q and Q.-and the frontier orbitals energies of SUMO (Q.-) and LUMO (Q) correlate with their oxidative and trypanocidal activity. QSAR analysis also highlighted that both bromine substitution in the p-quinone ring and a bulky phenyl group attached to the furane and thiazole rings (which generates a negative charge due to the 7C electron system polarized by the nearby heteroatoms) are favorable for activity.By combining experimental and in silico procedures, this study disclosed important information about p-qui-nones that may help to rationally tune their electronic properties and biological activities.
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    Orthopedic surgery residents' perception of online education in their programs during the COVID-19 pandemic: should it be maintained after the crisis?
    (2020) Figueroa, Francisco; Figueroa, David; Calvo-Mena, Rafael; Narvaez, Felipe; Medina, Natalia; Prieto, Juan
    Background and purpose - During the COVID-19 pandemic, most of the teaching centers in Chile have shifted to online resources. We decided to do a survey on orthopedic residents regarding this type of education to assess for strengths and weaknesses of digital education in orthopedic programs. Methods - A survey was performed targeting 110 orthopedic residents belonging to different training programs around the country. 100 residents completed the survey. Results - 86% stated that their programs are using online education. When asked in detail, 86% had been involved in webinars, 28% had received online presentations, 12% had participated in online tests, and 7% had evaluated patients. Webinars were rated (1 = very unsatisfactory, 10 = very satisfactory) with a mean grade of 8.1 (1-10), online presentations 7.3 (1-10), online tests 3.8 (1-8), and online patient evaluations 2.9 (1-9). When asked if, after the end of the pandemic, they would continue using the online modalities, 82% would continue attending webinars, 72% would continue watching online presentations, 27% would continue performing online tests, and 33% of the residents would continue performing online evaluations of patients. Interpretation - Even though resident evaluation of online activities is positive, face-to-face theoretical activities are still valued as a necessary complement for orthopedic residency education.
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    Tracing dissolved organic matter (DOM) from land-based aquaculture systems in North Patagonian streams
    (2015) Nimptsch Maass, Jorge; Woelfl, Stefan; Osorio, Sebastián; Valenzuela, José; Ebersbach, Paul; Tuempling, Wolf von; Palma, Rodrigo; Encina, Francisco; Figueroa, David; Kamjunke, Norbert; Graeber, Daniel
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    Trends in Total Knee Arthroplasty in a Developing Region: A Survey of Latin American Orthopaedic Surgeons
    (2020) Figueroa, David; Figueroa, Francisco; Calvo, Rafael; Vaisman, Alex; Figueroa, Maria; Putnis, Sven
    Introduction: A number of different total knee arthroplasty techniques are available. There is also a degree of surgeon preference for these, and the variation across orthopaedic surgeons in Latin America is currently unknown. Methods: A survey on members of Sociedad Latinoamericana de Artroscopia, Rodilla y Deporte was performed, with questions based on categories within worldwide national joint registries. In total, 315 Sociedad Latinoamericana de Artroscopia, Rodilla y Deporte members received the survey via e-mail, and the return answers were compared with the latest worldwide national joint registry annual reports. Results: The survey was completed in full by 262 surgeons (83%). It was answered that 19% of surgeons perform less than 10 total knee arthroplasties per year, 54% perform less than 30, and only 9% perform more than 100. Seventy-three percent of surgeons use a posterior stabilized total knee replacement, 18% use a cruciate retaining total knee replacement, and 9% use a medial pivot design. Forty-nine percent of surgeons resurface the patella, 27% never resurface it, and 24% choose to resurface it based on an individual case scenario. Ninety-eight percent of surgeons use cemented fixation in the femur and tibia, with the remaining 2% choosing hybrid fixation and 1% using fully noncemented fixation. Conclusion: This survey among Latin American surgeons has demonstrated important differences in surgical technique and implants choice compared with worldwide national registries.