Alberto Prats

Basal ganglia calcification induced by excitotoxicity: an experimental model characterised by electron microscopy and X-ray microanalysis

Abstract Activation of glutamate receptors induces an excitotoxic neurodegenerative process characterised in some brain areas by the formation of calcium precipitates. To examine the pathogenesis of basal ganglia calcification (BGC), an improved procedure of X-ray microanalysis was used to study experimental excitotoxic calcification in the rat. Three weeks after injection of ibotenic acid (IBO) in the rat basal forebrain, calcified inclusions within hypertrophied astrocytes were characterised. They appeared to form part of a filamentous structure localised in the cytoplasm in association with normal mitochondria and other organelles. Larger inclusions were surrounded by reactive microglia. The main inorganic components in these deposits were Ca and P, frequently accompanied by S, Al, Si and K. The shape and Ca/P molar ratio of the large deposits (> 10 μm) indicate that they may be biological apatites. Aluminosilicates were detected as small deposits (< 4 μm) free of other mineral constituents. To our knowledge this is the first report showing that IBO lesion induces brain accumulation of aluminosilicates similar to that described in Alzheimer’s or Fahr’s patients. Our data indicate that precipitation of Ca and Al may reduce their IBO-induced increased concentration. In conclusion, the experimental model and the improved efficiency of X-ray analysis described may help us to understand the pathogenesis of BGC.

Ultrasound-guided popliteal sciatic block with a single injection at the sciatic division results in faster block onset than the classical nerve stimulator technique.

BACKGROUND: For successful, fast-onset sciatic popliteal block (SPB), either a single injection above the division of the sciatic nerve, or 2 injections to block the tibial nerve (TN) and common peroneal nerve (CPN) separately have been recommended. In this study, we compared the traditional nerve stimulator (NS)-guided SPB above the division of the sciatic nerve with the ultrasound (US)-guided block with single injection of local anesthetic (LA) between the TN and CPN at the level of their division. We hypothesized that US-SPB with a single injection between TN and CPN would result in faster block onset than a single-injection NS-SPB. METHODS: Fifty-two patients were randomized to receive either an NS-SPB or a US-SPB. For both blocks, a single injection of 20 mL mepivacaine 1.5% was given using an automated injection pump while controlling for injection force. For NS-SPB, a TN response below 0.5 mA was sought 7 cm above the popliteal fossa crease (and proximal to the divergence of the TN and peroneal nerves). For US-SPB, the injection was made after a US-guided needle was inserted between the TN and CPN at the level of their separation. Motor response was not actively sought but registered if present. The location and spread of LA were evaluated by US in both groups. Onset of motor and sensory blocks was serially assessed in 5-minute intervals in the TN and CPN divisions and compared between the groups. RESULTS: All patients in both groups had successful block at 30 minutes after the injection, defined as sensory block to allow surgery without supplementation. A higher proportion of patients in the US-SPB group had a complete sensory (80% vs 4%, P < 0.001) and motor block (60% vs 8%, P < 0.001), defined as anesthesia and paralysis in all nerve territories, at 15 minutes after injection. US signs of intraepineural injection were present in 19 patients (73%) in the NS-SPB group and 25 patients (100%) in the US-SPB group (P < 0.001). CONCLUSIONS: A single injection of LA in US-SPB with needle insertion at the separation of the TN and CPN results in a similar success rate at 30 minutes; however, more patients in the US-SPB group than in the NS-SPB group had complete block at 15 minutes.

Pattern of Injury with a Graded Excitotoxic Insult and Ensuing Chronic Medial Septal Damage in the Rat Brain

Brain damage caused by an acute injury depends on the initial severity of the injury and the time elapsed after the injury. To determine whether these two variables activate common mechanisms, we compared the response of the rat medial septum to insult with a graded series of concentrations of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) with the time-course effects of a low dose of AMPA. For this purpose we conducted a dose-response study at concentrations of AMPA between 0.27 and 10.8 nmol to measure atrophy of the septal area, losses of cholinergic and GABAergic neurons, astroglial and microglial reactions, and calcification. Cholinergic neurons, whose loss paralleled the degree of septal atrophy produced by AMPA, are more sensitive than GABAergic neurons to the injury produced by AMPA. At doses of AMPA above 2.7 nmol, calcification and the degree of microglial reaction increased only in the GABAergic region of the septal area, whereas atrophy and neuronal loss reached a plateau. We chose the 2.7-nmol dose of AMPA to determine how these parameters were modified between 4 days and 6 months after injection. We found that atrophy and neuronal loss increased progressively through the 6-month study period, whereas astrogliosis ceased to be observed after 1 month, and calcium precipitates were never detected. We conclude that septal damage does not increase with the intensity of an excitotoxic insult. Rather, it progresses continuously after the insult. Because these two situations involve different mechanisms, short-term paradigms are inappropriate for interpreting the pathogenic mechanisms responsible for long-term neurodegenerative processes.

Morphological and Volumetric Assessment of Cerebral Ventricular System with 3D Slicer Software

We present a technological process based on the 3D Slicer software for the three-dimensional study of the brain’s ventricular system with teaching purposes. It values the morphology of this complex brain structure, as a whole and in any spatial position, being able to compare it with pathological studies, where its anatomy visibly changes. 3D Slicer was also used to obtain volumetric measurements in order to provide a more comprehensive and detail representation of the ventricular system. We assess the potential this software has for processing high resolution images, taken from Magnetic Resonance and generate the three-dimensional reconstruction of ventricular system.

Augmented reality techniques, using mobile devices, for learning human anatomy

We present a technological tool we developed under a portable environment by taking a specific fixed image from an anatomy atlas and visualizing it as a three dimensional and dynamic model; an enrichment of the anatomical image and an important aid in the student learning process. The system consists of an augmented reality library called Vuforia. After the images were scanned, they were stored in a database. The three dimensional models seen are created with Unity3D and Maya. The system allows Android and iOS platforms. The use of these mobile devices will allow managing the knowledge for students, developing new ways of teaching innovation and improving the quality of the academic process. These applications encourage student learning, promoting a more interactive attention. There is no doubt that smartphones and tablets are an additional teaching resource nowadays, they enrich and facilitate the transmission of educational contents in health science, specifically in the field of Human Anatomy.

Disminución del transportador de dopamina estriatal en primeros episodios psicóticos de pacientes esquizofrénicos tratados con risperidona

Resumen El parkinsonismo (PS) es uno de los efectos secundarios mas comunes de los farmacos antipsicoticos. Un 24 % de pacientes esquizofrenicos nunca tratados tienen PS, lo cual contrasta con el 1% observado en la poblacion normal. El 123I-FP-CIT podria determinar el estado funcional dopaminergico presinaptico de estos pacientes, ya que permite diferenciar PS degenerativo de no degenerativo. Objetivo Evaluar la concentracion del transportador de la dopamina (DAT) en un grupo homogeneo de pacientes jovenes diagnosticados de esquizofrenia durante su primer episodio. Material y metodo Estudio abierto, transversal. Se incluyeron 30 pacientes y 15 controles sanos. Los pacientes se trataron con dosis similares de risperidona y a todos los sujetos del estudio se les realizo una tomogammagrafia (SPECT) con 123I-FP-CIT. Se valoraron sintomas extrapiramidales y psicopatologicos mediante escalas Simpson-Angus, CGI y PANSS. El analisis de las imagenes de SPECT se realizo utilizando regions de interes (ROI) en nucleos caudados, putamen anterior, medio, posterior y cortex occipital. Resultados Los indices de captacion global de 123I-FP-CIT fueron significativamente menores en pacientes esquizofrenicos que en sujetos sanos (t = 2,56; p Conclusion En nuestra serie los pacientes esquizofrenicos con primer episodio psicotico tuvieron una disminucion significativa de la captacion estriatal del 123I-FP-CIT. Esta alteracion podria ser debida a la propia enfermedad o ser secundaria al tratamiento antipsicotico.

DTIWeb: a web-based framework for DTI data visualization and processing

Diffusion tensor imaging (DTI) is an extension of the conventional magnetic resonance imaging with the capability to characterize the diffusion behavior of water in a tissue. The study of DTI and its visualization has beome an emerging focus of research in brain studies since it provides the information required to reconstruct white matter fiber paths. In this paper, we present DTIWeb, a robust, portable and extensible Java application for visualizing and processing DTI data. The proposed framework is based on the Java3D programming platform that provides and object-oriented programming model and independence of computer hard-ware configuration and operating system. The platform is designed to work through the world wide web and only requires a web browser.

Computer-Based Visualization System for the Study of Deep Brain Structures Involved in Parkinson's Disease

Parkinson’s Disease is characterized by alterations in deep brain structures and pathways involved in movement control. However, the understanding of neuroanatomy and spatial relationships of deep brain structures remains a challenge for medical students. Recent developments in information technology may help provide new instructional material that addresses this problem. This paper aims to develop an interactive and digital tool to enhance the study of the anatomical and functional neurological basis involved in Parkinson’s Disease. This tool allows the organization and exploration of complex neuroanatomical contents related with Parkinson’s Disease in an attractive and interactive way. Educational implications of this tool are analyzed.

Application of the 3D slicer software in the study of the brain's ventricular system

We present a technological process based on the 3D Slicer software for the three-dimensional study of the brains ventricular system with teaching purposes. It values the morphology of this complex brain structure, in any spatial position or as a whole, being able to compare it with pathological studies where its anatomy visibly changes. This will lead to a better understanding of the ventricles anatomy and radiology. We assess the potential this software has for processing radiological images, taken from Magnetic Resonance serial sections and the three-dimensional reconstruction of anatomical structures.

Generation of teaching material through interactive electronic formats using iBook author

We present an example of an interactive electronic book developed using the iBook Author tool, designed by Apple for Mac OS. It is an easy system for the design of complementary teaching material in our university education systems, given its different presentation and development options. It features an interactive atlas for the study of the nervous system, through different neuroimaging techniques. The iBook format also allows the incorporation of dynamic animations that enable the understanding of an anatomical structure.