Review of the Brain's Behaviour after Injury and Disease for Its Application in an Agent-Based Model (ABM).

The brain is the most complex organ in the human body and, as such, its study entails great challenges (methodological, theoretical, etc.). Nonetheless, there is a remarkable amount of studies about the consequences of pathological conditions on its development and functioning. This bibliographic review aims to cover mostly findings related to changes in the physical distribution of neurons and their connections-the connectome-both structural and functional, as well as their modelling approaches. It does not intend to offer an extensive description of all conditions affecting the brain; rather, it presents the most common ones. Thus, here, we highlight the need for accurate brain modelling that can subsequently be used to understand brain function and be applied to diagnose, track, and simulate treatments for the most prevalent pathologies affecting the brain.

Using the Mooney Space to Characterize the Non-Affine Behavior of Elastomers.

The formulation of the entropic statistical theory and the related neo-Hookean model has been a major advance in the modeling of rubber-like materials, but the failure to explain some experimental observations such as the slope in Mooney plots resulted in hundreds of micromechanical and phenomenological models. The origin of the difficulties, the reason for the apparent need for the second invariant, and the reason for the relative success of models based on the Valanis-Landel decomposition have been recently explained. From that insight, a new micro-macro chain stretch connection using the stretch tensor (instead of the right Cauchy-Green deformation tensor) has been proposed and supported both theoretically and from experimental data. A simple three-parameter model using this connection has been suggested. The purpose of this work is to provide further insight into the model, to provide an analytical expression for the Gaussian contribution, and to provide a simple procedure to obtain the parameters from a tensile test using the Mooney space or the Mooney-Rivlin constants. From different papers, a wide variety of experimental tests on different materials and loading conditions have been selected to demonstrate that the simple model calibrated only from a tensile test provides accurate predictions for a wide variety of elastomers under different deformation levels and multiaxial patterns.

An Agent-Based Model to Reproduce the Boolean Logic Behaviour of Neuronal Self-Organised Communities through Pulse Delay Modulation and Generation of Logic Gates.

The human brain is arguably the most complex "machine" to ever exist. Its detailed functioning is yet to be fully understood, let alone modelled. Neurological processes have logical signal-processing and biophysical aspects, and both affect the brain's structure, functioning and adaptation. Mathematical approaches based on both information and graph theory have been extensively used in an attempt to approximate its biological functioning, along with Artificial Intelligence frameworks inspired by its logical functioning. In this article, an approach to model some aspects of the brain learning and signal processing is presented, mimicking the metastability and backpropagation found in the real brain while also accounting for neuroplasticity. Several simulations are carried out with this model to demonstrate how dynamic neuroplasticity, neural inhibition and neuron migration can reshape the brain's logical connectivity to synchronise signal processing and obtain certain target latencies. This work showcases the importance of dynamic logical and biophysical remodelling in brain plasticity. Combining mathematical (agents, graph theory, topology and backpropagation) and biomedical ingredients (metastability, neuroplasticity and migration), these preliminary results prove complex brain phenomena can be reproduced-under pertinent simplifications-via affordable computations, which can be construed as a starting point for more ambitiously accurate simulations.

A simple agent-based hybrid model to simulate the biophysics of glioblastoma multiforme cells and the concomitant evolution of the oxygen field.

BACKGROUND AND OBJECTIVES: Glioblastoma multiforme (GBM) is one of the most aggressive cancers of the central nervous system. It is characterized by a high mitotic activity and an infiltrative ability of the glioma cells, neovascularization and necrosis. GBM evolution entails the continuous interplay between heterogeneous cell populations, chemotaxis, and physical cues through different scales. In this work, an agent-based hybrid model is proposed to simulate the coupling of the multiscale biological events involved in the GBM invasion, specifically the individual and collective migration of GBM cells and the concurrent evolution of the oxygen field and phenotypic plasticity. An asset of the formulation is that it is conceptually and computationally simple but allows to reproduce the complexity and the progression of the GBM micro-environment at cell and tissue scales simultaneously. METHODS: The migration is reproduced as the result of the interaction between every single cell and its micro-environment. The behavior of each individual cell is formulated through genotypic variables whereas the cell micro-environment is modeled in terms of the oxygen concentration and the cell density surrounding each cell. The collective behavior is formulated at a cellular scale through a flocking model. The phenotypic plasticity of the cells is induced by the micro-environment conditions, considering five phenotypes. RESULTS: The model has been contrasted by benchmark problems and experimental tests showing the ability to reproduce different scenarios of glioma cell migration. In all cases, the individual and collective cell migration and the coupled evolution of both the oxygen field and phenotypic plasticity have been properly simulated. This simple formulation allows to mimic the formation of relevant hallmarks of glioblastoma multiforme, such as the necrotic cores, and to reproduce experimental evidences related to the mitotic activity in pseudopalisades. CONCLUSIONS: In the collective migration, the survival of the clusters prevails at the expense of cell mitosis, regardless of the size of the groups, which delays the formation of necrotic foci and reduces the rate of oxygen consumption.

Posterior hamstring harvest improves aesthetic satisfaction and decreases sensory complications as compared to the classic anterior approach in anterior cruciate ligament reconstruction surgery.

PURPOSE: The use of the posterior approach for harvesting hamstring grafts has recently become popular thanks to new all-inside techniques and retrograde drills. This study aims to compare the classic anterior approach with the posterior approach in the popliteal fossa. METHODS: Retrospective comparative study of 100 consecutive cases of primary ligamentoplasty performed using ipsilateral semitendinosus autograft with at least one year of follow-up. 50 patients with anterior approach (group A) and 50 patients with posterior approach (P). Ratio men/women: 9/1. Mean age: 32 ± 13 years. Mean operative time: 64.88 ± 12.28 min. STUDY VARIABLES: Graft harvest time; intraoperative complications (semitendinous [ST] tendon cut); postoperative neurological complications (allodynia, paresthesia, pain) or hematoma in the donor area; atrophy of the operated thigh compared to the contralateral thigh, postoperative VAS score, aesthetic satisfaction and overall satisfaction. RESULTS: Graft harvest time of 9.5 min in group A versus 5.25 min in group P (p < 0.05). Sensory complications: 16% in group A versus 2% in group P (p < 0.05). Regarding the patient's evaluation of the aesthetic result of the surgery, 80% in group A and 92% in group P were very satisfied, 16% in group A and 8% in group P were satisfied and 4% in group A and no patients in group P not very satisfied (p < 0.05). No significant differences were found in terms of total operative time, postoperative joint movement, atrophy of the operated thigh, postoperative VAS, or overall patient satisfaction. CONCLUSIONS: The posterior approach to harvesting the ipsilateral hamstring graft obtained better results than the anterior approach in terms of aesthetic satisfaction of the patient, lower rate of neurological complications (allodynia, paresthesias and hypoesthesia in the anterior region of the knee and leg) and shorter hamstring harvest time. LEVEL OF EVIDENCE: IV.

High prevalence of obstructive sleep apnea syndrome in Spain's Stroke Belt.

OBJECTIVE: Spain's so-called Stroke Belt is an area with high prevalence of vascular disease. We aimed to determine the prevalence of undetected obstructive sleep apnea-hypopnea syndrome (OSAHS) among patients with acute ischemic stroke (AIS) in southern Spain. METHODS: We conducted a cross-sectional study at the Virgen Macarena University Hospital Stroke Unit during 2018 to 2019. We included patients <72 hours after AIS with a neuroimaging lesion and performed sleep tests. RESULTS: Seventy-two patients were included. The median participant age was 72 years. Mean body mass index was 27.07 kg/m2, and 40.28% were daily alcohol drinkers. Hypertension, atrial fibrillation, ischemic cardiomyopathy, and previous stroke were detected in 63.9%, 11.1%, 15.3%, and 17.6% of patients, respectively. Polygraphy was feasible in 91.38% of patients. The prevalence of OSAHS was 84.72% (apnea-hypopnea index ≥5). Patients with moderate and severe OSAHS were more likely to be obese and to have a larger neck circumference and facial palsy. The diagnostic criteria of central sleep apnea syndrome were met in only 1.38% of patients. CONCLUSIONS: The high prevalence of OSAHS found in the Spanish Stroke Belt justifies further investigation and development of a screening program as a strategy to identify patients with undetected OSAHS.

Manejo del SAHS mediante dispositivos de avance mandibular. Estudio preliminar / Sleep apnea-hypopnea syndrome management using a mandibular advancement device. Preliminary study

El tratamiento que ha demostrado mayor eficacia en los pacientes con síndrome de apneas-hipopneas del sueño (SAHS) es la presión positiva continua de la vía aérea (CPAP). Los mayores inconvenientes son la incomodidad y la sensación de claustrofobia, que en algunos pacientes provoca rechazo o intolerancia. Una alternativa son los dispositivos de avance mandibular (DAM), que insertados en las arcadas dentarias producen el avance de la mandíbula y de la lengua, aumentando el volumen de la vía aérea. Objetivo: Presentar nuestra experiencia en el tratamiento del SAHS mediante dispositivos de avance mandibular tipo Herbst. Metodologia: Estudio de seguimiento prospectivo desde junio de 2006 hasta enero de 2009 de 7 pacientes del Área Hospitalaria Virgen Macarena con SAHS que rechazan el tratamiento con CPAP y a los que se ofrece tratamiento con DAM. Las variables analizadas son: índice de apneas-hipopneas por hora, índice de desaturaciones por hora, intensidad subjetiva del ronquido y el test de somnolencia de Epworth, antes del tratamiento y al menos 6 meses después desde el inicio de su uso. Utilizamos el test de Wilcoxon para detectar diferencias estadísticas significativas (p<0,05). Resultados: Se observó una reducción estadísticamente significativa del índice de apneahipopneas por hora (p<0,018) y del índice de desaturaciones por hora (p<0,018), así como una reducción no significativa del ronquido y de la somnolencia. Conclusiones: El uso de DAM tipo Herbst en pacientes afectos de SAHS que rechazan el uso de la CPAP podría ser útil, mejorando clínica y funcionalmente su situación(AU)

The most effective treatment in patients with sleep apnea-hypopnea syndrome (SAHS) is CPAP (continuous positive airway pressure). The main drawback of CPAP is the discomfort and claustrophobic sensation that it causes, which elicits rejection or intolerance by some patients. A non-surgical alternative to CPAP is the mandibular advancement device (MAD), which consists of a plastic splint inserted between the dental arches to shift the jaw and tongue forward and thus increase airway volume. Objective: Report our experience with the treatment of SAHS using the Herbst mandibular advancement device. Material and method: A prospective follow-up study was carried out from June 2006 until January 2009 at the Virgen Macarena University Hospital with 7 patients with SAHS who refused treatment with CPAP and were treated with the mandibular advancement device. The outcome variables analyzed were: apnea-hypopnea disruptions per hour index, desaturations per hour index, subjective intensity of snoring, and the Epworth Sleepiness Scale. Variables were evaluated pre-treatment and at least once 6 months after initiation MAD use. The Wilcoxon test for paired samples was used to detect statistically significant differences (p<0.05). Results: A statistically significant reduction in the hourly indices of apnea-hypopnea disruptions (p<0.018) and desaturations (p<0.018) was observed, as well as a statistically nonsignificant reduction in snoring and sleepiness. Conclusions: Use of the Herbst mandibular advancement device in patients with obstructive sleep apnea syndrome who refuse CPAP may be helpful as it improves the clinical and functional parameters of the condition(AU)