NSF DARE-Transforming modeling in neurorehabilitation: Four threads for catalyzing progress.

We present an overview of the Conference on Transformative Opportunities for Modeling in Neurorehabilitation held in March 2023. It was supported by the Disability and Rehabilitation Engineering (DARE) program from the National Science Foundation's Engineering Biology and Health Cluster. The conference brought together experts and trainees from around the world to discuss critical questions, challenges, and opportunities at the intersection of computational modeling and neurorehabilitation to understand, optimize, and improve clinical translation of neurorehabilitation. We organized the conference around four key, relevant, and promising Focus Areas for modeling: Adaptation & Plasticity, Personalization, Human-Device Interactions, and Modeling 'In-the-Wild'. We identified four common threads across the Focus Areas that, if addressed, can catalyze progress in the short, medium, and long terms. These were: (i) the need to capture and curate appropriate and useful data necessary to develop, validate, and deploy useful computational models (ii) the need to create multi-scale models that span the personalization spectrum from individuals to populations, and from cellular to behavioral levels (iii) the need for algorithms that extract as much information from available data, while requiring as little data as possible from each client (iv) the insistence on leveraging readily available sensors and data systems to push model-driven treatments from the lab, and into the clinic, home, workplace, and community. The conference archive can be found at (dare2023.usc.edu). These topics are also extended by three perspective papers prepared by trainees and junior faculty, clinician researchers, and federal funding agency representatives who attended the conference.

Computational modeling of dorsal root ganglion stimulation using an Injectrode.

Objective.Minimally invasive neuromodulation therapies like the Injectrode, which is composed of a tightly wound polymer-coated Platinum/Iridium microcoil, offer a low-risk approach for administering electrical stimulation to the dorsal root ganglion (DRG). This flexible electrode is aimed to conform to the DRG. The stimulation occurs through a transcutaneous electrical stimulation (TES) patch, which subsequently transmits the stimulation to the Injectrode via a subcutaneous metal collector. However, it is important to note that the effectiveness of stimulation through TES relies on the specific geometrical configurations of the Injectrode-collector-patch system. Hence, there is a need to investigate which design parameters influence the activation of targeted neural structures.Approach.We employed a hybrid computational modeling approach to analyze the impact of Injectrode system design parameters on charge delivery and neural response to stimulation. We constructed multiple finite element method models of DRG stimulation, followed by the implementation of multi-compartment models of DRG neurons. By calculating potential distribution during monopolar stimulation, we simulated neural responses using various parameters based on prior acute experiments. Additionally, we developed a canonical monopolar stimulation and full-scale model of bipolar bilateral L5 DRG stimulation, allowing us to investigate how design parameters like Injectrode size and orientation influenced neural activation thresholds.Main results.Our findings were in accordance with acute experimental measurements and indicate that the minimally invasive Injectrode system predominantly engages large-diameter afferents (Aß-fibers). These activation thresholds were contingent upon the surface area of the Injectrode. As the charge density decreased due to increasing surface area, there was a corresponding expansion in the stimulation amplitude range before triggering any pain-related mechanoreceptor (Aδ-fibers) activity.Significance.The Injectrode demonstrates potential as a viable technology for minimally invasive stimulation of the DRG. Our findings indicate that utilizing a larger surface area Injectrode enhances the therapeutic margin, effectively distinguishing the desired Aßactivation from the undesired Aδ-fiber activation.

A direct spinal cord-computer interface enables the control of the paralysed hand in spinal cord injury.

The paralysis of the muscles controlling the hand dramatically limits the quality of life of individuals living with spinal cord injury (SCI). Here, with a non-invasive neural interface, we demonstrate that eight motor complete SCI individuals (C5-C6) are still able to task-modulate in real-time the activity of populations of spinal motor neurons with residual neural pathways. In all SCI participants tested, we identified groups of motor units under voluntary control that encoded various hand movements. The motor unit discharges were mapped into more than 10 degrees of freedom, ranging from grasping to individual hand-digit flexion and extension. We then mapped the neural dynamics into a real-time controlled virtual hand. The SCI participants were able to match the cue hand posture by proportionally controlling four degrees of freedom (opening and closing the hand and index flexion/extension). These results demonstrate that wearable muscle sensors provide access to spared motor neurons that are fully under voluntary control in complete cervical SCI individuals. This non-invasive neural interface allows the investigation of motor neuron changes after the injury and has the potential to promote movement restoration when integrated with assistive devices.

Supraspinal control of motoneurons after paralysis enabled by spinal cord stimulation.

Spinal cord stimulation (SCS) restores motor control after spinal cord injury (SCI) and stroke. This evidence led to the hypothesis that SCS facilitates residual supraspinal inputs to spinal motoneurons. Instead, here we show that SCS does not facilitate residual supraspinal inputs but directly triggers motoneurons action potentials. However, supraspinal inputs can shape SCS-mediated activity, mimicking volitional control of motoneuron firing. Specifically, by combining simulations, intraspinal electrophysiology in monkeys and single motor unit recordings in humans with motor paralysis, we found that residual supraspinal inputs transform subthreshold SCS-induced excitatory postsynaptic potentials into suprathreshold events. We then demonstrated that only a restricted set of stimulation parameters enables volitional control of motoneuron firing and that lesion severity further restricts the set of effective parameters. Our results explain the facilitation of voluntary motor control during SCS while predicting the limitations of this neurotechnology in cases of severe loss of supraspinal axons.

SUPRASPINAL CONTROL OF MOTONEURONS AFTER PARALYSIS ENABLED BY SPINAL CORD STIMULATION.

Spinal cord stimulation (SCS) restores motor control after spinal cord injury (SCI) and stroke. This evidence led to the hypothesis that SCS facilitates residual supraspinal inputs to spinal motoneurons. Instead, here we show that SCS does not facilitate residual supraspinal inputs but directly triggers motoneurons action potentials. However, supraspinal inputs can shape SCS-mediated activity, mimicking volitional control of motoneuron firing. Specifically, by combining simulations, intraspinal electrophysiology in monkeys and single motor unit recordings in humans with motor paralysis, we found that residual supraspinal inputs transform subthreshold SCS-induced excitatory postsynaptic potentials into suprathreshold events. We then demonstrated that only a restricted set of stimulation parameters enables volitional control of motoneuron firing and that lesion severity further restricts the set of effective parameters. Our results explain the facilitation of voluntary motor control during SCS while predicting the limitations of this neurotechnology in cases of severe loss of supraspinal axons.

Restoration of sensory feedback from the foot and reduction of phantom limb pain via closed-loop spinal cord stimulation.

Restoring somatosensory feedback in individuals with lower-limb amputations would reduce the risk of falls and alleviate phantom limb pain. Here we show, in three individuals with transtibial amputation (one traumatic and two owing to diabetic peripheral neuropathy), that sensations from the missing foot, with control over their location and intensity, can be evoked via lateral lumbosacral spinal cord stimulation with commercially available electrodes and by modulating the intensity of stimulation in real time on the basis of signals from a wireless pressure-sensitive shoe insole. The restored somatosensation via closed-loop stimulation improved balance control (with a 19-point improvement in the composite score of the Sensory Organization Test in one individual) and gait stability (with a 5-point improvement in the Functional Gait Assessment in one individual). And over the implantation period of the stimulation leads, the three individuals experienced a clinically meaningful decrease in phantom limb pain (with an average reduction of nearly 70% on a visual analogue scale). Our findings support the further clinical assessment of lower-limb neuroprostheses providing somatosensory feedback.

Electrocatalytic on-site oxygenation for transplanted cell-based-therapies.

Implantable cell therapies and tissue transplants require sufficient oxygen supply to function and are limited by a delay or lack of vascularization from the transplant host. Previous exogenous oxygenation strategies have been bulky and had limited oxygen production or regulation. Here, we show an electrocatalytic approach that enables bioelectronic control of oxygen generation in complex cellular environments to sustain engineered cell viability and therapy under hypoxic stress and at high cell densities. We find that nanostructured sputtered iridium oxide serves as an ideal catalyst for oxygen evolution reaction at neutral pH. We demonstrate that this approach exhibits a lower oxygenation onset and selective oxygen production without evolution of toxic byproducts. We show that this electrocatalytic on site oxygenator can sustain high cell loadings (>60k cells/mm3) in hypoxic conditions in vitro and in vivo. Our results showcase that exogenous oxygen production devices can be readily integrated into bioelectronic platforms, enabling high cell loadings in smaller devices with broad applicability.

Miniature battery-free bioelectronics.

Miniature wireless bioelectronic implants that can operate for extended periods of time can transform how we treat disorders by acting rapidly on precise nerves and organs in a way that drugs cannot. To reach this goal, materials and methods are needed to wirelessly transfer energy through the body or harvest energy from the body itself. We review some of the capabilities of emerging energy transfer methods to identify the performance envelope for existing technology and discover where opportunities lie to improve how much-and how efficiently-we can deliver energy to the tiny bioelectronic implants that can support emerging medical technologies.

Assistive robotics should seamlessly integrate humans and robots.

Better integration of assistive robots with humans and adoption of a user-centric approach in their development will improve performance.

Computational modeling of dorsal root ganglion stimulation using an Injectrode.

Objective: Minimally invasive neuromodulation therapies like the Injectrode, which is composed of a tightly wound polymer-coated platinum/iridium microcoil, offer a low-risk approach for administering electrical stimulation to the dorsal root ganglion (DRG). This flexible electrode is aimed to conform to the DRG. The stimulation occurs through a transcutaneous electrical stimulation (TES) patch, which subsequently transmits the stimulation to the Injectrode via a subcutaneous metal collector. However, effectiveness of stimulation relies on the specific geometrical configurations of the Injectrode-collector-patch system. Hence, there is a need to investigate which design parameters influence the activation of targeted neural structures. Approach: We employed a hybrid computational modeling approach to analyze the impact of the Injectrode system design parameters on charge delivery and the neural response to stimulation. We constructed multiple finite element method models of DRG stimulation and multi-compartment models of DRG neurons. We simulated the neural responses using parameters based on prior acute preclinical experiments. Additionally, we developed multiple human-scale computational models of DRG stimulation to investigate how design parameters like Injectrode size and orientation influenced neural activation thresholds. Main results: Our findings were in accordance with acute experimental measurements and indicated that the Injectrode system predominantly engages large-diameter afferents (Aß-fibers). These activation thresholds were contingent upon the surface area of the Injectrode. As the charge density decreased due to increasing surface area, there was a corresponding expansion in the stimulation amplitude range before triggering any pain-related mechanoreceptor (Aδ-fibers) activity. Significance: The Injectrode demonstrates potential as a viable technology for minimally invasive stimulation of the DRG. Our findings indicate that utilizing a larger surface area Injectrode enhances the therapeutic margin, effectively distinguishing the desired Aß activation from the undesired Aδ-fiber activation.

Dynamic spinal reflex adaptation during locomotor adaptation.

The dynamics and interaction of spinal and supraspinal centers during locomotor adaptation remain vaguely understood. In this work, we use Hoffmann reflex measurements to investigate changes in spinal reflex gains during split-belt locomotor adaptation. We show that spinal reflex gains are dynamically modulated during split-belt locomotor adaptation. During first exposure to split-belt transitions, modulation occurs mostly on the leg ipsilateral to the speed change and constitutes rapid suppression or facilitation of the reflex gains, followed by slow recovery to baseline. Over repeated exposure, the modulation pattern washes out. We further show that reflex gain modulation strongly correlates with correction of leg asymmetry, and cannot be explained by speed modulation solely. We argue that reflex modulation is likely of supraspinal origins and constitutes an integral part of the neural substrate underlying split-belt locomotor adaptation.NEW & NOTEWORTHY This work presents direct evidence for spinal reflex modulation during locomotor adaptation. In particular, we show that reflexes can be modulated on-demand unilaterally during split-belt locomotor adaptation and speculate about reflex modulation as an underlying mechanism for adaptation of gait asymmetry in healthy adults.

Multi-enzyme catalysed processes using purified and whole-cell biocatalysts towards a 1,3,4-substituted tetrahydroisoquinoline.

In this work, two multi-enzyme catalysed processes to access a 1,3,4-substituted tetrahydroisoquinoline (THIQ), using either purified enzymes or lyophilised whole-cell catalysts, are presented. A key focus was the first step in which the reduction of 3-hydroxybenzoic acid (3-OH-BZ) into 3-hydroxybenzaldehyde (3-OH-BA) was catalysed by a carboxylate reductase (CAR) enzyme. Incorporation of the CAR-catalysed step enables substituted benzoic acids as the aromatic components, which can potentially be obtained from renewable resources by microbial cell factories. In this reduction, the implementation of an efficient cofactor regeneration system of both ATP and NADPH was crucial. Two different recycling approaches, either using purified enzymes or lyophilised whole-cells, were established and compared. Both of them showed high conversions of the acid into 3-OH-BA (>80%). However, the whole-cell system showed superior performance because it allowed the combination of the first and second steps into a one-pot cascade with excellent HPLC yields (>99%, enantiomeric excess (ee) ≥ 95%) producing the intermediate 3-hydroxyphenylacetylcarbinol. Moreover, enhanced substrate loads could be achieved compared to the system employing only purified enzymes. The third and fourth steps were performed in a sequential mode to avoid cross-reactivities and the formation of several side products. Thus, (1R,2S)-metaraminol could be formed with high HPLC yields (>90%, isomeric content (ic) ≥ 95%) applying either purified or whole-cell transaminases from Bacillus megaterium (BmTA) or Chromobacterium violaceum (Cv2025). Finally, the cyclisation step was performed using either a purified or lyophilised whole-cell norcoclaurine synthase variant from Thalictrum flavum (ΔTfNCS-A79I), leading to the formation of the target THIQ product with high HPLC yields (>90%, ic > 90%). As many of the educts applied are from renewable resources and a complex product with three chiral centers can be gained by only four highly selective steps, a very step- and atom efficient approach to stereoisomerically pure THIQ is shown.

Epidural stimulation of the cervical spinal cord for post-stroke upper-limb paresis.

Cerebral strokes can disrupt descending commands from motor cortical areas to the spinal cord, which can result in permanent motor deficits of the arm and hand. However, below the lesion, the spinal circuits that control movement remain intact and could be targeted by neurotechnologies to restore movement. Here we report results from two participants in a first-in-human study using electrical stimulation of cervical spinal circuits to facilitate arm and hand motor control in chronic post-stroke hemiparesis ( NCT04512690 ). Participants were implanted for 29 d with two linear leads in the dorsolateral epidural space targeting spinal roots C3 to T1 to increase excitation of arm and hand motoneurons. We found that continuous stimulation through selected contacts improved strength (for example, grip force +40% SCS01; +108% SCS02), kinematics (for example, +30% to +40% speed) and functional movements, thereby enabling participants to perform movements that they could not perform without spinal cord stimulation. Both participants retained some of these improvements even without stimulation and no serious adverse events were reported. While we cannot conclusively evaluate safety and efficacy from two participants, our data provide promising, albeit preliminary, evidence that spinal cord stimulation could be an assistive as well as a restorative approach for upper-limb recovery after stroke.

Using a high-frequency carrier does not improve comfort of transcutaneous spinal cord stimulation.

Objective.Spinal cord neuromodulation has gained much attention for demonstrating improved motor recovery in people with spinal cord injury, motivating the development of clinically applicable technologies. Among them, transcutaneous spinal cord stimulation (tSCS) is attractive because of its non-invasive profile. Many tSCS studies employ a high-frequency (10 kHz) carrier, which has been reported to reduce stimulation discomfort. However, these claims have come under scrutiny in recent years. The purpose of this study was to determine whether using a high-frequency carrier for tSCS is more comfortable at therapeutic amplitudes, which evoke posterior root-muscle (PRM) reflexes.Approach.In 16 neurologically intact participants, tSCS was delivered using a 1 ms long monophasic pulse with and without a high-frequency carrier. Stimulation amplitude and pulse duration were varied and PRM reflexes were recorded from the soleus, gastrocnemius, and tibialis anterior muscles. Participants rated their discomfort during stimulation from 0 to 10 at PRM reflex threshold.Main Results.At PRM reflex threshold, the addition of a high-frequency carrier (0.87 ± 0.2) was equally comfortable as conventional stimulation (1.03 ± 0.18) but required approximately double the charge to evoke the PRM reflex (conventional: 32.4 ± 9.2µC; high-frequency carrier: 62.5 ± 11.1µC). Strength-duration curves for tSCS with a high-frequency carrier had a rheobase that was 4.8× greater and a chronaxie that was 5.7× narrower than the conventional monophasic pulse, indicating that the addition of a high-frequency carrier makes stimulation less efficient in recruiting neural activity in spinal roots.Significance.Using a high-frequency carrier for tSCS is equally as comfortable and less efficient as conventional stimulation at amplitudes required to stimulate spinal dorsal roots.

Assessment of Safety of a Fully Implanted Endovascular Brain-Computer Interface for Severe Paralysis in 4 Patients: The Stentrode With Thought-Controlled Digital Switch (SWITCH) Study.

Importance: Brain-computer interface (BCI) implants have previously required craniotomy to deliver penetrating or surface electrodes to the brain. Whether a minimally invasive endovascular technique to deliver recording electrodes through the jugular vein to superior sagittal sinus is safe and feasible is unknown. Objective: To assess the safety of an endovascular BCI and feasibility of using the system to control a computer by thought. Design, Setting, and Participants: The Stentrode With Thought-Controlled Digital Switch (SWITCH) study, a single-center, prospective, first in-human study, evaluated 5 patients with severe bilateral upper-limb paralysis, with a follow-up of 12 months. From a referred sample, 4 patients with amyotrophic lateral sclerosis and 1 with primary lateral sclerosis met inclusion criteria and were enrolled in the study. Surgical procedures and follow-up visits were performed at the Royal Melbourne Hospital, Parkville, Australia. Training sessions were performed at patients' homes and at a university clinic. The study start date was May 27, 2019, and final follow-up was completed January 9, 2022. Interventions: Recording devices were delivered via catheter and connected to subcutaneous electronic units. Devices communicated wirelessly to an external device for personal computer control. Main Outcomes and Measures: The primary safety end point was device-related serious adverse events resulting in death or permanent increased disability. Secondary end points were blood vessel occlusion and device migration. Exploratory end points were signal fidelity and stability over 12 months, number of distinct commands created by neuronal activity, and use of system for digital device control. Results: Of 4 patients included in analyses, all were male, and the mean (SD) age was 61 (17) years. Patients with preserved motor cortex activity and suitable venous anatomy were implanted. Each completed 12-month follow-up with no serious adverse events and no vessel occlusion or device migration. Mean (SD) signal bandwidth was 233 (16) Hz and was stable throughout study in all 4 patients (SD range across all sessions, 7-32 Hz). At least 5 attempted movement types were decoded offline, and each patient successfully controlled a computer with the BCI. Conclusions and Relevance: Endovascular access to the sensorimotor cortex is an alternative to placing BCI electrodes in or on the dura by open-brain surgery. These final safety and feasibility data from the first in-human SWITCH study indicate that it is possible to record neural signals from a blood vessel. The favorable safety profile could promote wider and more rapid translation of BCI to people with paralysis. Trial Registration: ClinicalTrials.gov Identifier: NCT03834857.

Movimentos migratórios no Brasil: desafios para as políticas públicas de saúde e assistência social / Migratory movements in Brazil: challenges for public healthand social assistance / Movimientos migratorios en Brasil: desafíos para las políticas de salud pública y asistencia social

Este artigo aborda as relações entre migração, saúde e assistência social no Brasil. A problematização dessas questões salienta a forma como o Brasil coloca-se diante das novas ondas migratórias, bem como evidencia os desafios das políticas públicas brasileiras em relação ao acolhimento e ao acompanhamento dos(as) imigrantes no país. Através da revisão bibliográfica e documental, considerando as legislações que normatizam as migrações e o acesso às políticas públicas, busca-se tensionar as ações previstas nas leis e o panorama no qual se encontram os(as) imigrantes. O crescente fluxo de migrações, globalmente, destaca a necessidade de promoção do acesso às políticas públicas que contemplam os(as) migrantes, conforme ressaltam as discussões internacionais. Assim, no limite, a migração vem se constituindo como um determinante às políticas e às estratégias de saúde e de assistência social, especialmente nos países de acolhimento, consequentemente, no Brasil.

This article addresses the hip between migration and health and social assistance in Brazil. The problematization of these issues highlights the way in which Brazil faces new migratory waves, as well as the challenges of Brazilian public policies regarding the reception and monitoring of immigrants in country. Through a bibliographical and documentary review, considering the laws that regulate migration and access to public policies, we seek to stress the actions provided for in the laws and the panorama in which immigrants find mselves. The growing flow of migrations, on a global scale, highlights the need to promote access to public policies that contemplate migrants, as highlighted by international discussions. Thus, migration has become a determinant of health and social assistance policies and strategies, specially in host countries like Brazil.

Este artículo hace un abordaje a la relación entre migración, salud y asistencia social en Brasil. La problematización de estás cuestiones hacen enfoque en la forma como Brasil encara las nuevas olas migratorias, también nos muestra los desafíos de las políticas públicas brasileras en lo que se refiere al acogimiento y acompañamiento de los inmigrantes en el país. Por medio de la revisión bibliográfica y documental, se busca tensionar las acciones previstas en las leyes y el estado en el que se encuentran los inmigrantes. El creciente flujo de migraciones, apunta para la necesidad y promoción del acceso a políticas públicas que contemplan a los migrantes, conforme destacan las discusiones internacionales. Así, al límite, la migración viene siendo un determinante para las políticas, estrategias de salud y de asistencia social, especialmente en los países que acogen, consecuentemente, en Brasil.

Poststroke arm and hand paresis: should we target the cervical spinal cord?

Despite advances in understanding of corticospinal motor control and stroke pathophysiology, current rehabilitation therapies for poststroke upper limb paresis have limited efficacy at the level of impairment. To address this problem, we make the conceptual case for a new treatment approach. We first summarize current understanding of motor control deficits in the arm and hand after stroke and their shared physiological mechanisms with spinal cord injury (SCI). We then review studies of spinal cord stimulation (SCS) for recovery of locomotion after SCI, which provide convincing evidence for enhancement of residual corticospinal function. By extrapolation, we argue for using cervical SCS to restore upper limb motor control after stroke.

Alterações hepáticas e renais em trabalhadores rurais decorrentes da exposição a agrotóxicos: revisão sistemática / Liver and kidney changes resulting from exposure to pesticides in rural workers: systematic review

O objetivo deste estudo foi revisar a literatura científica acerca da exposição dos trabalhadores rurais aos agrotóxicos e a atuação desses agentes sobre as funções dos sistemas hepático e renal. O estudo em questão se trata de uma revisão sistemática produzida de acordo com a metodologia Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Para esta revisão foram feitas buscas nas bases Medline, PubMed, Scielo e Lilacs, nas quais foram inclusos artigos escritos em português e inglês no período de 2009 a 2018. Os descritores em saúde utilizados para a pesquisa foram: agroquímicos, trabalhadores rurais, saúde do trabalhador e biomarcadores. De 52 artigos selecionados, apenas oito preencheram os critérios de inclusão desta revisão. Após a análise dos oito artigos, pôde-se observar que os marcadores bioquímicos hepáticos citados com maior frequência nos artigos foram as transaminases, aspartato aminotransferase e alanina aminotransferase, presentes em todos os estudos (100%, n=8), seguido da gama-glutamiltransferase encontrada em 75% dos artigos (n=6). Por outro lado, os marcadores renais citados nos artigos foram apenas creatinina e ureia, com uma frequência de 62,5% (n=5) e 50% (n=4), respectivamente. Esses marcadores apresentaram-se dentro da normalidade em todos os estudos. Dessa forma, conclui-se que não houve evidências de alterações nos marcadores renais e hepáticos, porém os artigos relatam a existência de uma diferença entre o grupo exposto, trabalhadores que estavam em contato com agrotóxicos, e o grupo controle.

This study aimed to review the scientific literature about the exposure of rural workers to pesticides and their effects on the functions of the hepatic and renal systems. The study in question is a systematic review produced according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) methodology. For that, we searched the databases of Medline, PubMed, Scielo, and Lilacs, and articles written in Portuguese and English from 2009 to 2018 were included. The health descriptors used for the research were: agrochemicals, rural workers, occupational health, and biomarkers. Only eight out of the 52 articles selected initially met the inclusion criteria for this review. Their analysis showed that the most frequently cited liver biochemical markers were transaminases, aspartate aminotransferase, and alanine aminotransferase, present in all studies (100.0%, n=8). These were followed by the range-glutamyltransferase, found in 75.0% of the articles (n=6). On the other hand, the renal markers used in the articles were only creatinine and urea, with a frequency of 62.5% (n=5) and 50.0% (n=4), respectively. These markers were normal in all studies. Thus, we concluded that there was no evidence of changes in renal and hepatic markers. However, the articles do report differences between the exposed group, workers who were in contact with pesticides, and the control group.

Isolamento de amebas de vida livre potencialmente patogênicas em piscinas de uso coletivo localizadas no município de Redenção, Pará, Brasil / Isolation of potentially pathogenic free-living amoebae in swimming pools for collective use located in the municipality of Redenção, Pará, Brazil

Objetivo Isolar amebas dos gêneros Acanthamoeba e Naegleria em piscinas de uso coletivo do município de Redenção, Pará, Brasil. Métodos A identificação dessas amebas se deu a partir de amostras retiradas de piscinas de uso coletivo de quatro clubes da cidade. As análises foram realizadas a partir do exame direto a fresco, cultura, análise morfológica após coloração de Gram e teste de exflagelação, seguindo o protocolo descrito por Carlesso, Artuso e Rott. Resultados As amebas de vida livre foram encontradas em 41,67% das amostras, com predomínio das do gênero Acanthamoeba (63,2%) no exame direto a fresco. No clube A, localizado no setor Serrinha, houve predominância dessas amebas em relação às demais (8,34%). As amostras obtidas por swabs apresentaram 73,69% de formas evolutivas em comparação à análise feita apenas na água das piscinas. A confirmação dos gêneros das amebas presentes nas amostras feita através da coloração de Gram encontrou um perfil de identificação diferente, sendo que nesse exame a ameba de gênero Naegleriaspp. se sobressaiu perante a de gênero Acanthamoeba (61,11% e 38,89%, respectivamente). Conclusão Os resultados do estudo confirmam a presença de isolados potencialmente patogênicos de amebas de vida livre em piscinas de uso coletivo, o que pode significar um risco à saúde pública.

Objective To isolate amoebae of the genera Acanthamoeba and Naegleria in swimming pools for collective use in the municipality of Redenção, Pará, Brazil. Methods The identification of these amoebae was determined from samples of swimming pools for collective use in four private clubs in the city. The analysis methodology was performed based on direct fresh examination, culture, morphological analysis after Gram staining and exflagellation test, following the protocol described by Carlesso, Artuso and Rott. Results The frequency of free-living amoebae was 41.67%, with a predominance of the Acanthamoeba genus (63.2%) in direct fresh examination. At club A, located in the Serrinha sector, the frequency of these amoebae was higher than the others (8.34%). The samples obtained by swabs showed 73.69% of evolutionary forms in comparison to the analysis only of the water in the pools. The confirmation of the genera by Gram stain showed a different identification profile, in which Naegleria spp. stood out before the genus Acanthamoeba (61.11% and 38.89%, respectively). Conclusion In conclusion, the results of the study confirm the presence of potentially pathogenic isolates from free-living amoebae in swimming pools for collective use that may present risks to public health.