Open-Source Real-Time Closed-Loop Electrical Threshold Tracking for Translational Pain Research.

Nociceptors are a class of primary afferent neurons that signal potentially harmful noxious stimuli. An increase in nociceptor excitability occurs in acute and chronic pain conditions. This produces abnormal ongoing activity or reduced activation thresholds to noxious stimuli. Identifying the cause of this increased excitability is required for the development and validation of mechanism-based treatments. Single-neuron electrical threshold tracking can quantify nociceptor excitability. Therefore, we have developed an application to allow such measurements and demonstrate its use in humans and rodents. APTrack provides real-time data visualization and action potential identification using a temporal raster plot. Algorithms detect action potentials by threshold crossing and monitor their latency after electrical stimulation. The plugin then modulates the electrical stimulation amplitude using an up-down method to estimate the electrical threshold of the nociceptors. The software was built upon the Open Ephys system (V0.54) and coded in C++ using the JUCE framework. It runs on Windows, Linux, and Mac operating systems. The open-source code is available (https://github.com/Microneurography/APTrack). The electrophysiological recordings were taken from nociceptors in both a mouse skin-nerve preparation using the teased fiber method in the saphenous nerve and in healthy human volunteers using microneurography in the superficial peroneal nerve. Nociceptors were classified by their response to thermal and mechanical stimuli, as well as by monitoring the activity-dependent slowing of the conduction velocity. The software facilitated the experiment by simplifying the action potential identification through the temporal raster plot. We demonstrate real-time closed-loop electrical threshold tracking of single-neuron action potentials during in vivo human microneurography, for the first time, and during ex vivo mouse electrophysiological recordings of C-fibers and Aδ-fibers. We establish proof of principle by showing that the electrical threshold of a human heat-sensitive C-fiber nociceptor is reduced by heating the receptive field. This plugin enables the electrical threshold tracking of single-neuron action potentials and allows the quantification of changes in nociceptor excitability.

Evaluación de la reperfusión tras angiogénesis terapéutica con fotopletismografía en un modelo murino de isquemia de miembros inferiores / Evaluation of the reperfusion after angiogenic therapy with photoplethysmography in a murine model of limb ischemia

INTRODUCCIÓN: a pesar del extendido uso de la fotopletismografía (PPG) en clínica como test diagnóstico no invasivo de la isquemia, su utilización en experimentación animal es escasa. OBJETIVO: evaluar el valor de la PPG en el seguimiento de la reperfusión angiogénica en un modelo murino de isquemia periférica. MATERIAL Y MÉTODOS: en ratas macho Sprague Dawley se excluyeron los sectores arteriales ilíaco y femoral de la pata trasera izquierda. Como control se utilizó la pata contralateral. Los animales se dividieron en tres grupos: GH (n = 8), placebo (n = 6) y sham (n = 2). La perfusión fue evaluada mediante escalas clínica y funcional y por PPG. Toda recuperación de la onda de PPG mayor del 5% fue considerada significativa. Se diseñaron controles basales, a los 10, 20 y 30 días. Se calculó el cociente de pulsatilidad pata/pata (rpp), así como los cambios morfológicos de la onda de pulso. La relación entre variables cualitativas fue evaluada por test Chi-cuadrado y la de las variables cuantitativas, mediante t de Student. RESULTADOS: los valores basales de rpp entre patas mostraron gran variabilidad, pero con una correlación significativa positiva: 0.9 (0,74-0,97, IC 95%, p < 0,001). La media de incremento de rpp a 30 días fue mayor en el grupo GH: 0,3 (0-1,1), p = 0,097 frente a 0,03 (0-0,2), p = 0,81. El 62,5% de animales GH presentó una recuperación significativa de la onda frente al 20% en el grupo placebo (recuperación media de la onda: 45% frente a 15,8% [p = 0,086], GH y placebo, respectivamente). CONCLUSIONES: la fotopletismografía ha mostrado una sensibilidad adecuada para detectar pequeños cambios de perfusión en el modelo de isquemia propuesto y tras la administración de GH. Dicha prueba podría ser de utilidad como complemento en el seguimiento de la reperfusión angiogénica tras isquemia en el modelo de tipo murino

INTRODUCTION: despite the widespread use of photoplethysmography (PPG) in clinical practice as a non-invasive diagnostic test for ischemia, it has been little used in animal experimentation. OBJECTIVE: to evaluate PPG for the follow-up of angiogenic reperfusion after growth hormone (GH) therapy in a murine model of limb ischemia. MATERIAL AND METHODS: in male Sprague Dawley rats, the iliac and femoral arterial sectors of the left hind limb were excluded. As a control, the contralateral limb was used. The rats were divided into three groups: GH (n = 8), placebo (n= 6) and sham (n = 2). Besides PPG, the perfusion was evaluated by clinical and functional scores. Any recovery of the PPG wave greater than 5% was considered as significant. Controls at baseline, 10, 20 and 30 days were planned. The paw/paw pulsatility ratio (rpp) was calculated, as well as the morphological changes of the pulse wave. The relationship between qualitative variables was evaluated by Chi-square test, and that of quantitative variables by Student's t-test. RESULTS: the baseline values of rpp between limbs showed great variability, but with a significant positive correlation: 0.9 (0.74-0.97, 95% CI, p < 0.001). The mean increase in rpp at 30 days was higher in the GH group: 0.3 (0-1.1), p = 0.097 vs. 0.03 (0-0.2), p = 0.81. Among GH animals, 62.5% presented a significant recovery of the wave as compared to 20% in placebo group (average recovery of the wave: 45% vs. 15.8% [p = 0.086], GH and placebo, respectively). CONCLUSIONS: photoplethysmography has shown a suitable sensitivity to detect small changes of perfusion in the proposed ischemic model and after GH administration. The aforementioned test could be useful as a supplementary tool during the identification of the angiogenic reperfusión process after ischemia in a murine model

CT findings after laryngectomy.

The goal of surgical treatment of laryngeal cancer is to achieve tumor control while preserving, whenever possible, the three primary functions of the larynx: breathing, swallowing, and phonation. The surgical procedure may consist of either a partial, conservative excision (eg, cordectomy, vertical partial laryngectomy, horizontal supraglottic laryngectomy, supracricoid laryngectomy with cricohyoidopexy or cricohyoidoepiglottopexy, or near total laryngectomy) or a radical excision (total laryngectomy). The procedure depends largely on the location and extension of the tumor, the stage of disease, and the patient's needs and preferences. Familiarity with the typical imaging appearance of the larynx after each procedure is crucial for differentiating normal postsurgical changes from persistent or recurrent disease as well as for diagnosing associated second primary malignancies. Since computed tomography (CT) is often used for follow-up evaluations, an ability to interpret the characteristic CT features is particularly important.

Eficacia de la monoterapia con piperacilina-tazobactam en las infecciones del pie diabético / The effectiveness of piperacillin-tazobactam monotherapy in diabetic foot infections

Introducción. Las infecciones en el pie diabético constituyen un motivo habitual de consulta para los especialistas quirúrgicos y son en la actualidad el motivo más frecuente por el que los diabéticos ingresan en los hospitales, así como la causa principal de amputación no traumática. Objetivo. Estas infecciones son frecuentemente polimicrobianas, por lo que el objetivo del presente estudio ha sido evaluar la eficacia y la seguridad de un antibiótico de amplio espectro como la piperacilina-tazobactam en pacientes con infecciones graves del pie diabético. Pacientes y métodos. Estudio multicéntrico y prospectivo en donde 150 pacientes con infecciones del pie diabético recibieron piperacilina-tazobactam como tratamiento antibiótico. Resultados. La evolución clínica fue favorable en un 92,3% de los pacientes y la eficacia microbiológica obtenida al final del tratamiento fue del 89,9%. Se presentaron reacciones adversas al tratamiento en 10 pacientes (6,6%), y 84 necesitaron amputación (56%); se realizaron amputaciones menores en 78 enfermos y mayores en 6. Conclusiones. La eficacia clínica y microbiológica, junto con la escasez de efectos adversos presentados, hace de la piperacilina-tazobactam una alternativa eficaz en el manejo de estas infecciones

Introduction. Infections of the diabetic foot are a common reason for consulting surgical specialists, and are currently the most common cause of admission to hospital for diabetics and the main cause of non-traumatic amputation. Aim. These infections are often polymicrobial, therefore the objective of the present study has been to evaluate the efficacy and safety of a broad-spectrum antibiotic such as piperacillin-tazobactam in patients with severe infections of the diabetic foot. Patients and methods. Multi-centre, prospective study in which 150 patients with diabetic foot infection received piperacillin-tazobactam as antibiotic therapy. Results. Clinical outcome was favourable in 92.3% of patients and the microbiological efficacy obtained at the end of treatment was 89.9%. There were adverse reactions to treatment in 10 patients (6.6%) and 84 patients required amputation (56%), with minor amputations performed in 78 patients and major amputations in 6 patients. Conclusions. The clinical and microbiological efficacy and the lack of adverse events make piperacillin-tazobactam an efficacious alternative in the management of these infections