Artículos de publicaciones periódicas

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Open-source navigation system for tracking dissociated parts with multi-registration
(2021) Mancino, A. V.; Milano, F. E.; Risk, M. R.; Ritacco, L. E.
Purpose: During reconstructive surgery, knee and hip replacements, and orthognathic surgery, small misalignments in the pose of prosthesis and bones can lead to severe complications. Hence, the translational and angular accuracies are critical. However, traditional image-based surgical navigation lacks orientation data between structures, and imageless systems are unsuitable for cases of deformed anatomy. We introduce an open-source navigation system using a multiple registrations approach that can track instruments, implants, and bones to precisely guide the surgeon in emulating a preoperative plan. Methods: We derived the analytical error of our method and designed a set of phantom experiments to measure its precision and accuracy. Additionally, we trained two classification models to predict the system reliability from fiducial points and surface matching registration data. Finally, to demonstrate the procedure feasibility, we conducted a complete workflow for a real clinical case of a patient with fibrous dysplasia and anatomical misalignment of the right femur using plastic bones. Results: The system is able to track the dissociated fragments of the clinical case and averages alignment errors in the anatomical phantoms of 1.08 ± 0.68mm and 1.49 ± 1.19°. While the fiducial-points registration showed satisfactory results given enough points and covered volume, we acknowledge that the surface refinement step is mandatory when attempting surface matching registrations. Conclusion: We believe that our device could bring significant advantages for the personalized treatment of complex surgical cases and that its multi-registration attribute is convenient for intraoperative registration loosening cases.
Controlling neural activity: LPV modelling of optogenetically actuated Wilson-Cowan model
(2024) Martínez, S.; Sánchez-Peña, R. S.; García-Violini, D.
This paper aims to bridge the gap between neurophysiology and automatic control methodologies by redefining the Wilson-Cowan (WC) model as a control-oriented linear parameter-varying (LPV) system. A novel approach is presented that allows for the application of a control strategy to modulate and track neural activity. Approach: The WC model is redefined as a control-oriented LPV system in this study. The LPV modelling framework is leveraged to design an LPV controller, which is used to regulate and manipulate neural dynamics. Main results: Promising outcomes, in understanding and controlling neural processes through the synergistic combination of control-oriented modelling and estimation, are obtained in this study. An LPV controller demonstrates to be effective in regulating neural activity. Significance: The presented methodology effectively induces neural patterns, taking into account optogenetic actuation. The combination of control strategies with neurophysiology provides valuable insights into neural dynamics. The proposed approach opens up new possibilities for using control techniques to study and influence brain functions, which can have key implications in neuroscience and medicine. By means of a model-based controller which accounts for non-linearities, noise and uncertainty, neural signals can be induced on brain structures.
The impact of the succesive outbreaks of COVID-19, vaccination, and physical activity on mental health in the argentine population : a repeated cross-sectional study
(2024-02-26) Barbuzza, Alejo Ramiro; Ballarini, Fabricio; Goyeneche, Celina; Reppucci, Victoria; Benedetti, Pedro; Moscato, Franco; Medina, Jorge H.; Katche, Cynthia; Moncada, Diego; Viola, Haydeé
A controversy regarding the duration of generalized anxiety disorders (GAD) and depressive symptoms during the COVID-19 pandemic arose, stating that these symptoms last a short time, perhaps a few months, or that they are more persistent over time. After more than three years of the pandemic, this is still a question that requires an answer. The main goal of this work was to record the levels of self-perceived GAD and depression in the Argentine population at several time points during the pandemic to characterize whether they were transient or persisted over the successive waves of contagion. Furthermore, we studied the association between anti-COVID-19 vaccination and the high frequency of physical activity with GAD and depression levels to evaluate a possible protective role of these factors on mental health.
Enhanced retention of bacteria by TiO2 nanoparticles in saturated porous media
(2016) Gentile, Guillermina J.; Fidalgo de Cortalezzi, María M.
The simultaneous transport of TiO2 nanoparticles and bacteria Pseudomonas aeruginosa in saturated porous media was investigated. Nanoparticle and bacterium size and surface charge were measured as a function of electrolyte concentration. Sand column breakthrough curves were obtained for single and combined suspensions, at four different ionic strengths. DLVO and classical filtration theories were employed to model the interactions between particles and between particles and sand grains. Attachment of TiO2 to the sand was explained by electrostatic forces and these nanoparticles acted as bonds between the bacteria and the sand, leading to retention. Presence of TiO2 significantly increased the retention of bacteria in the sand bed, but microorganisms were released when nanomaterial influx ceased. The inclusion of nanomaterials in saturated porous media may have implications for the design and operation of sand filters in water treatment.
Detection of atypical response trajectories in biomedical longitudinal databases
(De Gruyter, 2022-10-24) Pantazis, Lucio José; García, Rafael Antonio
Many health care professionals and institutions manage longitudinal databases, involving follow-ups for different patients over time. Longitudinal data frequently manifest additional complexities such as high variability, correlated measurements and missing data. Mixed effects models have been widely used to overcome these difficulties. This work proposes the use of linear mixed effects models as a tool that allows to search conceptually different types of anomalies in the data simultaneously.
Field Evaluation of Novel Spatial Repellent Controlled Release Devices (CRDs) against Mosquitoes in an Outdoor Setting in the Northern Peruvian Amazon
(Tropical Medicine and Infectious Disease, 7(11), 372. MDPI AG, 2022) Flores-Mendoza, Carmen; López-Sifuentes, Victor M.; Vásquez, Gissella M.; Stoops, Craig A.; Fisher, Michael L.; Bernier, Ulrich R.; Perry, Melynda; Mollica, Juan; Coltzau, Damián A.; Gurman, Pablo; D’hers, Sebastián; Elman, Noel M.
U.S. military troops are exposed to mosquito-borne pathogens when deployed to endemic regions. Personal protective measures such as permethrin-treated uniforms and dermal repellents are the cornerstones of mosquito-borne disease prevention for the U.S. military. These measures have limitations and additional personal protection tools, such as spatial repellent devices to decrease the risk of vector-borne pathogen transmission, are required. Novel spatial repellent controlled-release devices formulated with metofluthrin were evaluated in an outdoor setting in the northern Amazon of Peru to evaluate performance under field conditions. The metofluthrin emitting devices lowered the number of mosquitoes captured in protected human landing collections (HLC) compared to blank devices, although there were effect differences between Anopheles spp. and species in other mosquito genera. A computational-experimental model was developed to correlate HLC and active ingredient (AI) concentrations as a function of time and space. Results show a strong correlation between the released AI and the decrease in HLC. This model represents the first effort to obtain a predictive analytical tool on device performance using HLC as the entomological endpoint.
Spatial repellents transfluthrin and metofluthrin affect the behavior of Dermacentor variabilis, Amblyomma americanum, and Ixodes scapularis in an in vitro vertical climb assay
(Plos One, 2022) Siegel, Eric L.; Olivera, Marcos; Martínez Roig, Esteban; Perry, Melynda; Li, Andrew Y.; D'hers, Sebastián; Elman, Noel M.; Rich, Stephen M.
Repellents serve an important role in bite protection. Tick repellents largely rely on biomechanisms that induce responses with direct contact, but synthetic pyrethroids used as spatial repellents against insects have received recent attention for potential use in tick protection systems. An in vitro vertical climb assay was designed to assess spatial repellency against Dermacentor variabilis, Amblyomma americanum, and Ixodes scapularis adult, female ticks. Climbing behavior was assessed with and without the presence of two spatial repellents, transfluthrin and metofluthrin. Repellency parameters were defined to simulate the natural questing behavior of ambushing ticks, including measures of detachment, pseudo-questing duration, climbing deterrence, and activity. Significant effects were observed within each parameter. D. variabilis showed the greatest general susceptibility to each repellent, followed by A. americanum, and I. scapularis. The most important and integrative measure of repellency was climbing deterrence–a measure of the spatial repellent’s ability to disrupt a tick’s natural propensity to climb. Transfluthrin deterred 75% of D. variabilis, 67% of A. americanum, and 50% of I. scapularis. Metofluthrin was slightly more effective, deterring 81% of D. variabilis, 73% of A. americanum, and 72% of I. scapularis. The present study poses a novel paradigm for repellency and reports a preliminary assessment of spatial repellent effect on tick behavior. Further research will assess spatial repellency in a more natural setting, scale exposure conditions, and incorporate host cues.
Second wave of COVID-19 pandemic in Argentinian population: vaccination is associated with a decrease in depressive symptoms
(2022-06) Benedetti, Pedro; Barbuzza, Alejo; Moscato, Franco; Reppucci, Victoria; Goyeneche, Celina; Katche, Cynthia; Medina, Jorge Horacio; Viola, Haydeé; Ballarini, Fabricio; Moncada, Diego
"Since the irruption of the coronavirus disease 2019 (COVID-19) the planet has submerged in a time of concern and uncertainty, with a direct impact on people's mental health. Moreover, the recurrent outbreaks that periodically harry different regions of the world constantly refocus people's concerns to the pandemic. Yet, each new wave heats the diverse countries in different situations, including the advances in their vaccination campaigns. In this research, we studied the levels of the general anxiety disorder (GAD) and depression in the Argentine population across the first and second waves of infections that occurred in our country."
Automated detection and quantification of reverse triggering efort under mechanical ventilation
(2021-02-15) Pham, Tài; Montanya, Jaume; Telias, Irene; Piraino, Thomas; Magrans, Rudys; Coudroy, Rémi; Damiani, L. Felipe; Mellado Artigas, Ricard; Madorno, Matías; Blanch, Lluis; Brochard, Laurent
"Reverse triggering (RT) is a dyssynchrony defned by a respiratory muscle contraction following a passive mechanical insufation. It is potentially harmful for the lung and the diaphragm, but its detection is challenging. Magnitude of efort generated by RT is currently unknown. Our objective was to validate supervised methods for automatic detection of RT using only airway pressure (Paw) and fow. A secondary objective was to describe the magnitude of the eforts generated during RT."
Prevalence of reverse triggering in early ARDS: results from a multicenter observational study
(2021-01) Rodríguez, Pablo Oscar; Tiribelli, Norberto; Fredes, Sebastián; Gogniat, Emiliano; Plotnikow, Gustavo A.; Fernández Ceballos, Ignacio; Pratto, Romina A.; Raimondi, Alejandro C.; Guaymas, María; Ilutovich, Santiago; San Román, Eduardo; Madorno, Matías; Maskin, Luis Patricio; Brochard, Laurent; Setten, Mariano
"Background: The prevalence of reverse triggering (RT) in the early phase of ARDS is unknown. Research question: During early ARDS, what is the proportion of patients affected by RT, what are its potential predictors, and what is its association with clinical outcomes? Study design and methods: This was prospective, multicenter, and observational study. Patients who met the Berlin definition of ARDS with less than 72 h of mechanical ventilation and had not been paralyzed with neuromuscular blockers were screened. A 30-min recording of respiratory signals was obtained from the patients as soon as they were enrolled, and the number of breaths with RT were counted."
A control strategy for a tethered follower robot for pulmonary rehabilitation
(2020-12-03) Bianchi, Luciano Gustavo; Buniak, Esteban Alejandro; Ramele, Rodrigo; Santos, Juan Miguel
"Patients that suffer Chronic Obstructive Pulmonary Disease (COPD) undergo a procedure called Pulmonary Rehabilitation that helps them to improve disease prognosis. Pulmonary Rehabilitation consists of different physical exercises and walking activities conducted at medical facilities under supervision of a physical therapist. In order to perform these procedures, patients require oxygen assistance, but the oxygen tank cannot be carried by the patient due to the musculoskeletal atrophy that characterize this pathology and external assistance is required. The assistance to transport the bulky oxygen tank can be provided by a robotic device that follows the patient while performing the physical activities. This work provides an initial study on the controlling mechanism of a differential tethered robot that implements a leader-follower configuration to carry the oxygen tank for these procedures. Two alternative control strategies are proposed. Results on a simulated and on a real prototype confirms the feasibility of the proposed solution."
Effect of PEEP on dead space in an experimental model of ARDS
(2020) Tusman, Gerardo; Gogniat, Emiliano; Madorno, Matías; Otero, Pablo; Dianti, José; Fernández Ceballos, Ignacio; Ceballos, Martín; Verdier, Natalí; Böhm, Stephan H.; Rodríguez, Pablo Oscar; San Román, Eduardo
"Background: Difference between Bohr and Enghoff dead space are not well described in ARDS patients. We aimed to analyze the effect of PEEP on the Bohr and Enghoff dead spaces in a model of ARDS. Methods: 10 pigs submitted to randomized PEEP steps of 0, 5, 10, 15, 20, 25 and 30 cm H2O were evaluated with the use of lung ultrasound images, alveolar-arterial oxygen difference (P(A-a)O2), transpulmonary mechanics, and volumetric capnography at each PEEP step. Results: At PEEP > 15 cm H2O, atelectasis and P(A-a)O2 progressively decreased while endinspiratory transpulmonary pressure (PL), end-expiratory PL, and driving PL increased (all P < .001). Bohr dead space (VDBohr/VT), airway dead space (VDaw/VT), and alveolar dead space (VDalv/VTalv) reached their highest values at PEEP 30 cm H2O (0.69 0.10, 0.53 0.13 and 0.35 0.06, respectively). At PEEP <15 cm H2O, the increases in atelectasis and P(A-a)O2 were associated with negative end-expiratory PL and highest driving PL. VDBohr/VT and VDaw/VT showed the lowest values at PEEP 0 cm H2O (0.51 0.08 and 0.32 0.08, respectively), whereas VDalv/VTalv increased to 0.27 0.05. Enghoff dead space and its derived VDalv/VTalv showed high values at low PEEPs (0.86 0.02 and 0.79 0.04, respectively) and at high PEEPs (0.84 0.04 and 0.65 0.12), with the lowest values at 15 cm H2O (0.77 0.05 and 0.61 0.11, respectively; all P < .001). CONCLUSIONS: Bohr dead space was associated to lung stress, whereas Enghoff dead space was partially affected by the shunt effect. Key words: dead space; PEEP; lung stress; ARDS; VILI; carbon dioxide."
Obtaining accurate and calibrated coil models for transcranial magnetic stimulation using magnetic field measurements
(2020) Mancino, Axel; Milano, Federico E.; Martín-Bertuzzi, Fiorella; Yampolsky, C. G.; Ritacco, Lucas E.; Risk, Marcelo
"Currently, simulations of the induced currents in the brain produced by transcranial magnetic stimulation (TMS) are used to elucidate the regions reached by stimuli. However, models commonly found in the literature are too general and neglect imperfections in the windings. Aiming to predict the stimulation sites in patients requires precise modeling of the electric field (E-field), and a proper calibration to adequate to the empirical data of the particular coil employed. Furthermore, most fabricators do not provide precise information about the coil geometries, and even using X-ray images may lead to subjective interpretations. We measured the three components of the vector magnetic field induced by a TMS figure-8 coil with spatial resolutions of up to 1 mm. Starting from a computerized tomography-based coil model, we applied a multivariate optimization algorithm to automatically modify the original model and obtain one that optimally fits the measurements. Differences between models were assessed in a human brain mesh using the finite-elements method showing up to 6% variations in the E-field magnitude. Our calibrated model could increase the precision of the estimated E-field induced in the brain during TMS, enhance the accuracy of delivered stimulation during functional brain mapping, and improve dosimetry for repetitive TMS."
Pandemia COVID-19: ¿un cambio de paradigma en Occidente?
(2020-05) Conti, Merlina; Bellucci, Pamela; Schick, Martín; Trobbiani, María Julieta; Jullier, Natalia; Panza, Gustavo; Garayalde, Damián; Mateo, Nahuel; Rojas, Ezequiel; Sánchez, Cristian
"Elaboramos recomendaciones basadas en la evidencia para administrar los recursos imprescindibles en los centros sanitarios, en contexto de pandemia, en un país de bajos recursos económicos. Se realizaron búsquedas MedLine utilizando términos MeSH “Pneumonia, viral/prevention and control”, “Pneumonia, viral/transmission”, “Coronavirus Infections/prevention and control”, “Coronavirus Infections/transmission”, “COVID-19”, “Masks/classification”, “Masks/microbiology”, “Respiratory Protective Devices”, entre otros. Se recomienda que la población general porte mascarilla. A nivel institucional, la ventilación y el correcto distanciamiento de las camas son medidas de prevención efectivas. El factor más importante en la contención de un brote es la identificación oportuna de pacientes infectados. Se recomienda el uso de presión negativa y sistemas de ventilación. Ante la escasez de mascarillas tipo N95, el uso de protectores faciales totales y mascarilla quirúrgica es una opción factible. Proponemos una estrategia integral con medidas de afrontamiento para entidades sanitarias y la sociedad en general."
Herramienta web para post-análisis de simulaciones de dinámica molecular
(2013) Borgna, Karina Giselle; Fernández, María Laura; Risk, Marcelo
"En este trabajo se busca desarrollar una aplicación web interactiva y personalizada que permita analizar resultados generados mediante simulaciones de dinámica molecular. Con esta herramienta se pretende analizar las propiedades cada átomo o molécula de manera individual o conjunta a partir de una trayectoria, permitiendo segmentaciones tridimensionales que el usuario puede personalizar, así como análisis estadísticos no disponibles en las aplicaciones de post análisis que brindan los paquetes de dinámica molecular. Una herramienta de estas características es de gran ayuda en el estudio de los datos obtenidos permitiendo al usuario proponer el análisis o representación de los mismos que considere necesarios. Para este trabajo, como ejemplo, se tomaron datos generados por el programa Gromacs y fueron incorporados a una base de datos desarrollada en un entorno web. Se seleccionaron simulaciones de una bicapa lipídica expuesta a un campo eléctrico por el gran costo computacional que presenta de modo de generar una aplicación que pueda ser capaz de analizar datos independientemente de la demanda que éstos requieran. El sitio web se desarrolló con el framework Django, el cual permite utilizar Python, mientras que la base de datos se implementó en PostgreSQL. Se obtuvo una aplicación web que permite cargar datos de una trayectoria y generar un análisis estadístico, así como gráficos y representaciones espaciales. Se propone generar modelos 3D que permitan estimar superficie o volumen de la selección de átomos que el usuario considere necesarios."
Real-time detection of imminent ventricular fibrillation using mean and standard deviation of beat-to-beat HRV
(2018) Mosquera, Candelaria; Racca, Dora María; Quintero-Rincón, Antonio
"It is estimated that 50% of all cardiovascular deaths are caused by a sudden cardiac arrest (SCA), which represents 15% of global mortality, and its main cause is ventricular fibrillation (VF). Therefore, it is of interest to design new methods capable to detect changes in heart rate (HR or RR interval) that could announce the beginning of an imminent fibrillation. In this work, an effective novel indicator, based on mean and standard deviation of Heart Rate Variability (HRV), was studied and used to develop an algorithm that predicts imminent VF with 100% sensitivity and 100% specificity. The study was based on 65 RR intervals signals. The algorithm’s simplicity provides a quick-to-use implementation in a micro controller unit (MCU) for real-time VF detection, allowing its application in a variety of medical devices with electrocardiogram (ECG) modules."
Hand bone conduction sound study by using the DSP Logger MX 300
(2020) Adler, Melanie Victoria; Fialá Sánchez, Mariana; Martini, Constanza; Vartabedian, Luciana Mariam; Zazzali, Matías Nicolás; Quintero-Rincón, Antonio
"Bone conduction is the transmission of acoustic energy to the inner ear by different paths involving the bones of the skull. In this work, we use the path the hand provides in order to transmit the sound coming from the cell phone using Bluetooth system. The aim of this work was to study the vibrations produced by a sound transmitted through bone conduction between a mobile phone and the hand analyzed with the DSP Logger MX equipment."
Study on epileptic seizure detection in EEG signals using largest Lyapunov exponents and logistic regression
(2019) Quintero-Rincón, Antonio; Flugelman, Máximo; Prendes, Jorge; D'Giano, Carlos
"Seizure detection plays a central role in most aspects of epilepsy care. Understanding the complex epileptic signals system is a typical problem in electroencephalographic (EEG) signal processing. This problem requires different analysis to reveal the underlying behavior of EEG signals. An example of this is the non-linear dynamic: mathematical tools applied to biomedical problems with the purpose of extracting features or quantifying EEG data. In this work, we studied epileptic seizure detection independently in each brain rhythms from a multilevel 1D wavelet decomposition followed by the independent component analysis (ICA) representation of multivariate EEG signals. Next, the largest Lyapunov exponents (LLE) and their scaling given by its standard deviation are estimated in order to obtain the vectors to be used during the training and classification stage. With this information, a logistic regression classification is proposed with the aim of discriminating between seizure and non-seizure. Preliminary experiments with 99 epileptic events suggest that the proposed methodology is a powerful tool for detecting seizures in epileptic signals in terms of classification accuracy, sensitivity and specificity."
Spike-and-wave detection in epileptic signals using cross-correlation and decision trees
(2018) Quintero-Rincón, Antonio; Alanis, Manuela; Muro, Valeria; D'Giano, Carlos
"Identify spike-and-waves patterns in epileptic signals is a typical problem in electroencephalographic (EEG) signal processing. In this paper we propose cross-correlation coupled with decision tree model as new method in order to assess and detect spike-and-wave discharges (SWD) in long-term epileptic signals. The proposed approach is demonstrated in terms of accuracy, sensitivity and specificity classification on real EEG signals using a database developed with medical annotations."
Nanobioingeniería: historia y futuro
(2015) Risk, Marcelo
"Las aplicaciones de la nanotecnología desde la ingeniería a los ámbitos de la biología y la medicina constituyen la nanobioingeniería. Entonces la nanobioingeniería se puede describir como un área de trabajo multidisciplinaria, donde convergen las ciencias básicas como biología, matemática, química y física, con la medicina, la electrónica, la mecánica, informática y los aspectos éticos y legales."

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