Mechanical disturbances applied by motorized ankle foot orthosis to adapt ankle muscles activation-A validation study.

Background: Reduced function of ankle muscles usually leads to impaired gait. Motorized ankle foot orthoses (MAFOs) have shown potential to improve neuromuscular control and increase volitional engagement of ankle muscles. In this study, we hypothesize that specific disturbances (adaptive resistance-based perturbations to the planned trajectory) applied by a MAFO can be used to adapt the activity of ankle muscles. The first goal of this exploratory study was to test and validate two different ankle disturbances based on plantarflexion and dorsiflexion resistance while training in standing still position. The second goal was to assess neuromuscular adaptation to these approaches, namely, in terms of individual muscle activation and co-activation of antagonists. Methods: Two ankle disturbances were tested in ten healthy subjects. For each subject, the dominant ankle followed a target trajectory while the contralateral leg was standing still: a) dorsiflexion torque during the first part of the trajectory (Stance Correlate disturbance-StC), and b) plantarflexion torque during the second part of the trajectory (Swing Correlate disturbance-SwC). Electromyography was recorded from the tibialis anterior (TAnt) and gastrocnemius medialis (GMed) during MAFO and treadmill (baseline) trials. Results: GMed (plantarflexor muscle) activation decreased in all subjects during the application of StC, indicating that dorsiflexion torque did not enhance GMed activity. On the other hand, TAnt (dorsiflexor muscle) activation increased when SwC was applied, indicating that plantarflexion torque succeeded in enhancing TAnt activation. For each disturbance paradigm, there was no antagonist muscle co-activation accompanying agonist muscle activity changes. Conclusion: We successfully tested novel ankle disturbance approaches that can be explored as potential resistance strategies in MAFO training. Results from SwC training warrant further investigation to promote specific motor recovery and learning of dorsiflexion in neural-impaired patients. This training can potentially be beneficial during intermediate phases of rehabilitation prior to overground exoskeleton-assisted walking. Decreased activation of GMed during StC might be attributed to the unloaded body weight in the ipsilateral side, which typically decreases activation of anti-gravity muscles. Neural adaptation to StC needs to be studied thoroughly in different postures in futures studies.

Post-stroke rehabilitation of the ankle joint with a low cost monoarticular ankle robotic exoskeleton: Preliminary results.

Introduction: Stroke generates a high rate of disability and, in particular, ankle spasticity is a sequelae that interferes with the execution of daily activities. Robotic devices have been proposed to offer rehabilitation treatments to recover control of ankle muscles and hence to improve gait function. Objective: The aim of this study is to investigate the effects of passive stretching, combined with active and resisted movement, accompanied by visual feedback, by means of playful interactive software using a low-cost monoarticular robot (MEXO) in patients with stroke sequelae and spastic ankle. Methods: An open, uncontrolled, non-randomised, quasi-experimental study of 6 weeks duration has been completed. A protocol has been defined to determine the usability, safety and potential benefits of supplementary treatment with the MEXO interactive system in a group of patients. Nine volunteer patients with sequelae of stroke who met the inclusion criteria were included. They received conventional treatment and in addition also received treatment with the MEXO monoarticular robot three times a week during 6 weeks. Each session consisted of 10 min of passive stretching followed by 20 min of active movement training with visual feedback (10 min active without resistance, 10 min with resistance) and a final phase with 10 min of passive stretching. The following variables were measured pre- and post-treatment: joint range of motion and ankle muscle strength, monopodal balance, muscle tone, gait ability and satisfaction with the use of assistive technology. Results: Statistically significant improvements were obtained in joint range measured by goniometry and in balance measured by monopodal balance test. Also in walking capacity, through the measurement of travelled distance. Discussion and significance: Device usability and patient safety were tested. Patients improved joint range and monopodal balance. The MEXO exoskeleton might be a good alternative for the treatment of spastic ankle joint in people with a stroke sequela.

Transcranial Magnetic Stimulation Following a Paired Associative Stimulation Protocol Based on a Video Game Neuromodulates Cortical Excitability and Motor Behavior.

Transcranial Magnetic Stimulation (TMS) can be used to modulate cortico-spinal excitability following a paired associative stimulation (PAS) protocol. Movement-related cortical stimulation (MRCS) is a PAS protocol based on the synchronization of a single-pulse TMS with a movement task. However, plasticity and motor performance potentiation due to MRCS has been related exclusively to single-movement tasks. In order to unveil the effects of an MRCS protocol in complex movements, we applied PAS synchronized with a movement-related dynamic task (MRDT) with a customized video game. In 22 healthy subjects, we measured the reaction time (RT), trajectory error (TE), and the number of collected and avoided items when playing the custom video game to evaluate the task motor performance. Moreover, we assessed the recruitment curve of Motor Evoked Potentials (MEPs) with five different intensities to evaluate the motor corticospinal excitability. MEPs were recorded in Abductor Pollicis Brevis (APB) and Abductor Digiti Minimi (ADM), before, right after, and 30 min after the PAS intervention, in an active versus sham experimental design. The MRCS PAS intervention resulted in RT reduction, and motor corticospinal excitability was modulated, reflected as significant MEP amplitude change at 110% RMT intensity in ADM and at 130% RMT intensity in APB. RTs and ADM MEP amplitudes correlated positively in specific time and intensity assessments. We conclude that the proposed PAS protocol facilitated RT performance in a complex task. This phenomenon might be useful to develop neurorehabilitation strategies with complex movements, similar to activities of daily living.

Competitive Debate: A Successful Inter-team Gamification Experience in the Human Resources Subject.

Students demand more active and participating teaching innovation methods, and activities such as presentations are not enough to satisfy those demands. In this research, competitive debate is used as inter-team gamification with third year students from a Business School studying the Human Resources Management subject. Out of this experience, qualitative and quantitative data are obtained. Results reinforce the continuation of classroom competitive debate due to the evidence of its motivational, learning, and communication skills improvement, and knowledge acquisition effects. The possibility of application with actual professionals is seriously considered.

Competitive Debate as Innovation in Gamification and Training for Adult Learners: A Conceptual Analysis.

Adult learners demand teaching innovations that are ever more rapid and attractive. As a response to these demands and the challenges of skills training, this article presents a conceptual analysis that introduces competitive debate as an impact training model. The aim is to learn whether debate can be considered to fall within the frame of gamification, so that the full potential of debate as gamification can be exploited. There is a significant research gap regarding competitive debate as a game, with the training mechanics for adult learners remaining practically unexplored. Through a conceptual analysis of game, game experience, and gamification, and their respective characteristics, we conclude that competitive debate is an ideal instrument for gamification.

Pharmacokinetics of levofloxacin after single intravenous and oral administration, and its interaction with sucralfate in mixed-breed dogs.

The study aims to establish the plasma pharmacokinetic parameters of levofloxacin in mixed-breed dogs, at a single dose of 5 mg/kg, intravenously, orally only and orally with sucralfate pre-treatment (1 g per animal), to evaluate its influence on antimicrobial absorption. Concentrations of levofloxacin in plasma were determined using high-performance liquid chromatography (HPLC) with fluorescence detection. After iv of levofloxacin, the mean (±SD) of AUC0-24, Vz, t½λz and MRT, was 19.05 ± 6.4 µg-h/ml, 2.43 ± 0.5 L/kg, 7.93 ± 1.41 hours and 8.7 ± 1.5 hours, respectively. After oral administration, the C max, t½λz and bioavailability were 1.95 ± 0.7 µg/ml, 7.65 ± 1.38 hours and 71.93 ± 9.75%, respectively. In animals given an oral dose of levofloxacin with sucralfate pre-treatment, there was a significant decrease (p < 0.05) in C max (0.57 ± 0.23 µg/ml), AUC (5.73 ± 2.26 µg-h/ml) and bioavailability (31.92 ± 14.19%). In the dogs studied, it is suggested that the dose 5 mg/kg of levofloxacin for both routes is inadequate to meet PK-PD targets for susceptible bacteria using breakpoints established by the Institute of Clinical and Laboratory Standards (CLSI).

Haptic Adaptive Feedback to Promote Motor Learning With a Robotic Ankle Exoskeleton Integrated With a Video Game.

Background: Robotic devices have been used to rehabilitate walking function after stroke. Although results suggest that post-stroke patients benefit from this non-conventional therapy, there is no agreement on the optimal robot-assisted approaches to promote neurorecovery. Here we present a new robotic therapy protocol using a grounded exoskeleton perturbing the ankle joint based on tacit learning control. Method: Ten healthy individuals and a post-stroke patient participated in the study and were enrolled in a pilot intervention protocol that involved performance of ankle movements following different trajectories via video game visual feedback. The system autonomously modulated task difficulty according to the performance to increase the challenge. We hypothesized that motor learning throughout training sessions would lead to increased corticospinal excitability of dorsi-plantarflexor muscles. Transcranial Magnetic Stimulation was used to assess the effects on corticospinal excitability. Results: Improvements have been observed on task performance and motor outcomes in both healthy individuals and post-stroke patient case study. Tibialis Anterior corticospinal excitability increased significantly after the training; however no significant changes were observed on Soleus corticospinal excitability. Clinical scales showed functional improvements in the stroke patient. Discussion and Significance: Our findings both in neurophysiological and performance assessment suggest improved motor learning. Some limitations of the study include treatment duration and intensity, as well as the non-significant changes in corticospinal excitability obtained for Soleus. Nonetheless, results suggest that this robotic training framework is a potentially interesting approach that can be explored for gait rehabilitation in post-stroke patients.

Pharmacokinetics and tissue disposition of enrofloxacin in rainbow trout after different routes of administration.

Plasma pharmacokinetics (PK) and tissue disposition of enrofloxacin (EFX) was studied in rainbow trout (Oncorhynchus mykiss) after a single oral administration of 10 mg/kg, and by immersion baths of 20 ppm during 2.5 h and 100 ppm during 0.5 h, at water temperature of 16.3 ± 0.3 °C.Concentrations of EFX in plasma and tissues (skin, muscle, liver, kidney and gut) were determined using high performance liquid chromatography (HPLC) with fluorescence detection.Pharmacokinetic parameters were analyzed with a non-compartmental model. After oral administration, t½ß, AUC and AUCtissues/AUCplasma ratio were 42.98 h, 21.80µg-h/ml and ≤ 18.63, respectively.After immersion baths of 20 ppm during 2.5 h and 100 ppm during 0.5 h, the t½ß, AUC and AUCtissues/AUCplasma were 42.77 and 44.67, 9.83 and 12.83 µg-h/ml and ≤ 9.81 and ≤ 7.13, respectively.Therefore, oral (10 mg/kg) and bath administration in rainbow trout can provide AUC/MIC of ≥125 and Cmax/MIC of ≥10 to treat diseases caused by susceptible bacteria with MIC ≤ 0.04 µg/ml. This information can be helpful for the right use of EFX in rainbow trout. Also, this is the first study that determines the antibiotic tissue disposition in rainbow trout by using different administration routes.

HYBRID: Ambulatory Robotic Gait Trainer with Movement Induction and Partial Weight Support.

Robotic exoskeletons that induce leg movement have proven effective for lower body rehabilitation, but current solutions offer limited gait patterns, lack stabilization, and do not properly stimulate the proprioceptive and balance systems (since the patient remains in place). Partial body weight support (PBWS) systems unload part of the patient's body weight during rehabilitation, improving the locomotive capabilities and minimizing the muscular effort. HYBRID is a complete system that combines a 6DoF lower body exoskeleton (H1) with a PBWS system (REMOVI) to produce a solution apt for clinical practice that offers improves on existing devices, moves with the patient, offers a gait cycle extracted from the kinematic analysis of healthy users, records the session data, and can easily transfer the patient from a wheelchair to standing position. This system was developed with input from therapists, and its response times have been measured to ensure it works swiftly and without a perceptible delay.

Voluntary control of wearable robotic exoskeletons by patients with paresis via neuromechanical modeling.

BACKGROUND: Research efforts in neurorehabilitation technologies have been directed towards creating robotic exoskeletons to restore motor function in impaired individuals. However, despite advances in mechatronics and bioelectrical signal processing, current robotic exoskeletons have had only modest clinical impact. A major limitation is the inability to enable exoskeleton voluntary control in neurologically impaired individuals. This hinders the possibility of optimally inducing the activity-driven neuroplastic changes that are required for recovery. METHODS: We have developed a patient-specific computational model of the human musculoskeletal system controlled via neural surrogates, i.e., electromyography-derived neural activations to muscles. The electromyography-driven musculoskeletal model was synthesized into a human-machine interface (HMI) that enabled poststroke and incomplete spinal cord injury patients to voluntarily control multiple joints in a multifunctional robotic exoskeleton in real time. RESULTS: We demonstrated patients' control accuracy across a wide range of lower-extremity motor tasks. Remarkably, an increased level of exoskeleton assistance always resulted in a reduction in both amplitude and variability in muscle activations as well as in the mechanical moments required to perform a motor task. Since small discrepancies in onset time between human limb movement and that of the parallel exoskeleton would potentially increase human neuromuscular effort, these results demonstrate that the developed HMI precisely synchronizes the device actuation with residual voluntary muscle contraction capacity in neurologically impaired patients. CONCLUSIONS: Continuous voluntary control of robotic exoskeletons (i.e. event-free and task-independent) has never been demonstrated before in populations with paretic and spastic-like muscle activity, such as those investigated in this study. Our proposed methodology may open new avenues for harnessing residual neuromuscular function in neurologically impaired individuals via symbiotic wearable robots.

Joint stiffness modulation of compliant actuators for lower limb exoskeletons.

Lower limb exoskeletons are being used to assist people with movement disorders during activities of daily living or rehabilitation. However, providing a natural interface that automatically adapts to the patient's movement limitations remains an open challenge. In this paper, we present a control implementation that combines a compliant actuator technology with the concept of tacit learning to improve the synchronisation between the exoskeleton and the user during locomotion. We show that this implementation can be effectively used to easily modulate the joint stiffness that is perceived by the user during locomotion. This scheme set the base for the implementation of an automatically shared control between the exoskeleton and its user.

BioMot exoskeleton - Towards a smart wearable robot for symbiotic human-robot interaction.

This paper presents design of a novel modular lower-limb gait exoskeleton built within the FP7 BioMot project. Exoskeleton employs a variable stiffness actuator in all 6 joints, a directional-flexibility structure and a novel physical humanrobot interfacing, which allows it to deliver the required output while minimally constraining user's gait by providing passive degrees of freedom. Due to modularity, the exoskeleton can be used as a full lower-limb orthosis, a single-joint orthosis in any of the three joints, and a two-joint orthosis in a combination of any of the two joints. By employing a simple torque control strategy, the exoskeleton can be used to deliver user-specific assistance, both in gait rehabilitation and in assisting people suffering musculoskeletal impairments. The result of the presented BioMot efforts is a low-footprint exoskeleton with powerful compliant actuators, simple, yet effective torque controller and easily adjustable flexible structure.

A closed-loop brain-computer interface triggering an active ankle-foot orthosis for inducing cortical neural plasticity.

In this paper, we present a brain-computer interface (BCI) driven motorized ankle-foot orthosis (BCI-MAFO), intended for stroke rehabilitation, and we demonstrate its efficacy in inducing cortical neuroplasticity in healthy subjects with a short intervention procedure (∼15 min). This system detects imaginary dorsiflexion movements within a short latency from scalp EEG through the analysis of movement-related cortical potentials (MRCPs). A manifold-based method, called locality preserving projection, detected the motor imagery online with a true positive rate of 73.0 ± 10.3%. Each detection triggered the MAFO to elicit a passive dorsiflexion. In nine healthy subjects, the size of the motor-evoked potential (MEP) elicited by transcranial magnetic stimulation increased significantly immediately following and 30 min after the cessation of this BCI-MAFO intervention for ∼15 min ( p = 0.009 and , respectively), indicating neural plasticity. In four subjects, the size of the short latency stretch reflex component did not change following the intervention, suggesting that the site of the induced plasticity was cortical. All but one subject also performed two control conditions where they either imagined only or where the MAFO was randomly triggered. Both of these control conditions resulted in no significant changes in MEP size (p = 0.38 and p = 0.15). The proposed system provides a fast and effective approach for inducing cortical plasticity through BCI and has potential in motor function rehabilitation following stroke.

Analysis of the techniques for thoracic- and lumbar-level localization during posterior spine surgery and the occurrence of wrong-level surgery: results from a national survey.

BACKGROUND CONTEXT: Despite the frequency with which surgeons perform posterior spinal surgery and the precautions against wrong-site surgery, operations on incorrect levels still occur. Wrong-level exposure is documented in 0.32% to 15% of cases. Additionally, there is little consensus as to what is the most accurate method for localizing the correct spinal level. PURPOSE: The purpose of this study is to investigate the most commonly used localization methods and their association with wrong-level surgery, to determine the prevalence of wrong-level localization, and to identify circumstances commonly associated with wrong-level surgery, and to offer recommendations that may reduce the incidence of these errors. STUDY DESIGN/SETTING: This was an online survey study that was distributed to North American Spine Society (NASS) members (including both orthopedic surgeons and neurosurgeons). The survey was sent as a Web link within an e-mail. PATIENT SAMPLE: A total of 2,338 surgeons received the survey, 532 opened the survey, and 173 completed it (7.4% response rate). The survey was only sent once, as recommended by NASS. Of those that responded, 72% (124 of 173) were orthopedic surgeons, 28% (49 of 173) were neurosurgeons, and 73% (126 of 173) were spine fellowship trained. OUTCOME MEASURES: We sought to investigate self-reported localization methods that are most commonly used (both anatomic landmarks and imaging techniques), the prevalence of wrong-level surgery, and any correlations between localization method and wrong-level surgery. METHODS: An eight-question anonymous survey was distributed to members of NASS, including orthopedic surgeons and neurosurgeons. There was no pilot testing or validation performed for this survey. The survey was sent as a Web link within an e-mail. Some questions asked surgeons to select as many responses as applicable, and others allowed surgeons to describe in detail any cases of wrong-level surgery. This study neither requires nor receives funding; additionally, no conflicts of interests were reported. RESULTS: Fluoroscopy was the most commonly used imaging technique for thoracic and lumbar surgeries (89% and 86%, respectively), followed by plain radiographs (54% and 58%, respectively). Surgeons were allowed to select as many responses as applicable, and 76 surgeons reported using both plain radiographs and fluoroscopy. The facet joint with corresponding pedicle was the most commonly used anatomic landmark for localization of thoracic and lumbar surgeries (67% and 59%, respectively), followed by the spinous process (49% and 52%, respectively). Sixty-eight percent of surgeons admitted to wrong-level localization, some of which were rectified intraoperatively, during their careers. Fifty-six percent of these surgeons reported using plain radiographs and 44% used fluoroscopy when the errors occurred. Common sources of preoperative errors included failure to visualize known reference points, recognize unconventional spinal anatomy, and adequately visualize the level because of large body habitus. Common sources of intraoperative errors included poor communication, failure to relocalize after exposure, and poor counting methods. CONCLUSIONS: Despite the variety of localization modalities, most surgeons use only a few. Whereas wrong-level localization is relatively rare, the ideal frequency is never. There is no standard approach that will entirely eliminate these mistakes; however, using a localization time out and increasing awareness of common sources of error may help decrease the incidence of wrong-level spine surgery.

Composition and biting activity of Anopheles (Diptera: Culicidae) in the Amazon region of Colombia.

To provide information for public health policy on mosquito nets in the Amazon region of Colombia, we conducted landing catches to estimate Anopheles species composition and biting activity. Two hundred twenty person-nights of catches were done in seven locations over a period of 14 mo. A total of 1,780 Anopheles mosquitoes were caught (8.1 per person-night). Among the nine species found, An. oswaldoi Peryassú was the most common (776 mosquitoes, 44%), followed by An. darlingi Root s.l. (498, 28%). An. oswaldoi was the most common species collected outdoors, where its biting rate dropped steadily from a peak of >15 bites/person-night at the start of the night (1800-1900 hours) to approximately equal to 2 bites/person-night before dawn. An. darlingi was the most common species collected indoors, with a biting rate of approximately equal to 3-4 bites/person-night until about midnight, when the rate dropped below 1 bite/person-night, before showing a secondary peak before dawn. Sixty-four mosquito nets were analyzed by the technique of high-performance liquid chromatography (HPLC) for levels of deltamethrin (DM). All but two (62) of these were reported by their owners to have been impregnated with insecticide, and 53 were found by HPLC to have deltamethrin. However, one half (32) of the nets had concentrations <4 mg/m2 and therefore were likely to have been inadequately protective. An inverse association was found between the reported time between washes and deltamethrin concentration. These findings show a need for additional protection from mosquitoes when not inside nets, as well as for more effective impregnation, possibly through wash-resistant insecticide formulation.

Farmacocinética plasmática de la balofloxacina en terneros / Farmacocinética plasmática de balofloxacin em bezerros / Plasma pharmacokinetic of balofloxacin in calves

Los parámetros farmacocinéticos de absorción y disposición de balofloxacina se determinaron en terneros hembras raza holando-argentino (n = 6), luego de una dosis única de 5 mg/kg administrada en bolo intravenoso y subcutáneo, en un diseño cruzado de tratamiento. El analito se determinó en muestras de plasma por método microbiológico de difusión en agar utilizando como microorganismo detector una solución de esporas de Bacillus subtilis BGA y medio de cultivo Antibiotic Nº 1. Las concentraciones plasmáticas de balofloxacina en función del tiempo se analizaron por el modelo cinético no compartimental utilizando el software PK Solution 2.0. Los parámetros farmacocinéticos obtenidos fueron para la vía intravenosa: t1/2  = 2.3 ± 1.1 h; Cltotal área= 10.2 ± 3.4 ml/min/kg; Vdárea= 1.8 ± 0.3 L/kg; ABCárea= 551.3 ± 247.0 g/min/ml. Excepto para CltotaL área y ABCárea, los valores obtenidos para la administración intravenosa difirieron significativamente de los obtenidos del ensayo por vía subcutánea (p<0.05), para el cual se obtuvo un Cmáx= 1.3 ± 0.4 g/ml, con un tmáx= 51 ± 12.1 minutos y una biodisponibilidad cercana al 98%. El valor de Vdárea superior a 1 l/kg obtenido con ambas vías de aplicación indica buena capacidad para difundir a territorios extravasculares y tejidos.

Pharmacokinetic parameters of absorption and disposition of balofloxacin were determined in female Holando-Argentinean calves (n = 6), after a 5 mg/kg single dose, administered as both intravenous and subcutaneous bolus, in a crossed-over design treatment. The analyte was determined in plasma samples by microbiological method in agar diffusion, using a Bacillus subtilis BGA spore solution as microorganism detector in agar Antibiotic Nº 1. The plasmatic concentrations of balofloxacin based on the time were analyzed by a non compartimental kinetic model using software PK Solution 2.0. The intravenous pharmacokinetic parameters obtained were: t1/2β= 2.3 ± 1.1 h; Cltotal area= 10.2 ± 3.4 ml/min/kg; Vdárea= 1.8 ± 0.3 L/kg; and AUCárea= 551.3 ± 247.0 μg/min/ml. Except for Cltotal area and AUCarea, the values obtained for the intravenous administration significantly differed from the obtained ones for the subcutaneous route (p<0.05), for which Cmax= 1.3 ± 0.4 μg/ml, tmax= 51 ± 12.1 minutes and bioavailability values close to 98% were obtained. The Vdarea value was superior to 1 l/kg for both routes of application and indicates good capacity to spread to extravascular area and tissues.

Os parâmetros farmacocinéticos de absorção e eliminação dos balofloxacin foi determinada nos bezerros Holando-argentina (n = 6), depois de uma dose única de 5 mg/kg, uma vez que ambos foram administrados em bolus por via intravenosa e subcutânea, em um design de tratamento cruzado. O analito foi determinado em amostras de plasma por método microbiológico de difusão em ágar, utilizando uma solução de esporos de microorganismo Bacillus subtilis BGA como detector em ágar antibiótica Nº 1. As concentrações plasmáticas de balofloxacin com base no tempo não foram analisados por um modelo de cinética compartimental usando software PK Solução 2,0. O parâmetros farmacocinéticos da via intravenosa obtidos foram: t1/2 β = 2.3 ± 1.1 h; Cltotal área = 10.2 ± 3.4 ml / min / kg; Vdárea = 1.8 ± 0.3 l/kg; e AUCárea = 551,3 ± 247,0 μg/min/ml. Exceto para Cltotal área e AUCárea, os valores obtidos para a administração intravenosa diferiu significativamente do obtido para a via subcutânea, (p<0,05), para a qual Cmax = 1.3 ± 0.4 μ g/ml, tmax = 51 ± 12.1 minutos e biodisponibilidade perto de 98% foram obtidos. O valor Vdarea foi superior a 1 l/kg para ambas as vias de aplicação e indica uma boa capacidade de propagação de espaço extravascular e tecidos.

Farmacocinética y biodisponibilidad de ceftiofur sódico en caprinos / Pharmacokinetics and bioavailability of ceftiofur sodium in goats

Se determinaron parámetros farmacocinéticos de ceftiofur sódico con dosis única de 2.2 mg/kg por vía intravenosa e intramuscular, en un diseño cruzado de tratamiento en hembras caprinas adultas no gestantes (n= 6). Las concentraciones plasmáticas en función del tiempo se determinaron por el método microbiológico de difusión en agar utilizando medio Mueller-Hinton y Providencia alcalifaciens, cuyo límite de cuantificación se estableció en 0.039 μg/ml. Los datos de concentración plasmática de ceftiofur en función del tiempo se analizaron por el modelo farmacocinético no compartimental utilizando el sofwarePK Solution 2.0. Los parámetros obtenidos para la vía intravenosa fueron: vida media de eliminación (t1/2 b)= 1.63 ± 0.04 horas, clearance total (Cltot)= 3.3 ± 1.1 ml/kg/min, volumen de distribución (Vdss)= 0.38 ± 0.19 L/kg, área bajo la curva (ABC)= 716.5 ± 225.5 μg/min/ml. Estos valores no difieren significativamente de los obtenidos del ensayo intramuscular (p < 0.05) y son similares a los informados en otras especies animales con ceftiofur. En el ensayo intramuscular se obtuvo una concentración máxima (Cmáx) de 3.6 ± 0.5 μg/ml, con un tiempo máximo (tmáx) de 0.53 ± 0.31 horas y elevada biodisponibilidad (97.6 ± 0.1 por ciento). Los resultados indican que la aplicación intramuscular provee rápida absorción y óptima biodisponibilidad, generando niveles plasmáticos que exceden la concentración inhibitoria mínima (CIM) de patógenos respiratorios sensibles durante 12 horas. Considerando estos resultados y laCIM90 (£ 0.06 μg/ml) frente a bacterias como Pasteurella haemolitica y multocida, se propone como tratamiento de este tipo de cuadros infecciosos en caprinos, una dosis de mantenimiento de 1.3 mg/kg cada 12 horas por vía intramuscular, cuyo predictor de eficacia (t > CIM) se calculó en 77.8 por ciento.

Residuos de enrofloxacina y ciprofloxacina en músculo de pollos parrilleros / Residues of enrofloxacin and ciprofloxacin in muscle of broiler chickens

Las fluoroquinolonas son antimicrobianos de uso intensivo en medicina veterinaria. En Argentina la enrofloxacina es empleada en planteles avícolas y porcinos. La Ciprofloxacina, es un metabolito dela anterior que es empleada en medicina humana y es considerada una alternativa en medicina veterinaria. Niveles de residuos de enrofloxacina y ciprofloxacina se determinaron en forma simultánea en músculo de pollos naturalmente infectados con Mycoplasma spp. y tratados con estos antimicrobianos (5 mg/kg/12h oral) durante 5 días. El objetivo de este trabajo fue establecer el momento adecuado de sacrificio de los animales, para su comercialización en buenas condiciones clínicas y niveles aceptables de residuos. Se sacrificaron animales a cinco tiempos pos- tratamiento; 200 mg de músculo pectoral homogeneizados en buffer fosfato se desproteinizaron, evaporaron y eluyeron por cromatografía líquida de alta presión con detección por fluorescencia. La concentración de residuos de enrofloxacina fue máxima a las 24 h de finalizado el tratamiento (0.073 + 0.006 mg/g), inferior al límite máximo de residuos establecido por entes reguladores internacionales (0.3 mg/g). Los niveles máximos (0.027 + 0.015 mg/g) se detectaron para ciprofloxacina a las 72 h. Es necesario desarrollar y examinar métodossimples y precisos para cuantificar residuos en diferentes productos y tejidos comestibles, promover la aplicación de buenas prácticas agrícolas y elaborar regulaciones pertinentes.