Dolor en pediatría / Pediatric pain

Enero 20, 2018. No. 2969

Los enfoques metodológicos actuales en la evaluación de la modulación condicionada del dolor en pediatría. Current methodological approaches in conditioned pain modulation assessment in pediatrics. Hwang PS1, Ma ML1,2,3, Spiegelberg N1, Ferland CE1,2,3,4,5. Author information J Pain Res. 2017 Dec 12;10:2797-2802. doi: 10.2147/JPR.S150857. eCollection 2017. Abstract Conditioned pain modulation (CPM) paradigms have been used in various studies with healthy and non-healthy adult populations in an attempt to elucidate the mechanisms of pain processing. However, only a few studies so far have applied CPM in pediatric populations. Studies finding associations with chronic pain conditions suggest that deficiencies in underlying descending pain pathways may play an important role in the development and persistence of pain early in life. Twelve studies were identified using a PubMed search which examine solely pediatric populations, and these are reviewed with regard to demographics studied, methodological approaches, and conclusions reached. This review aimed to provide both clinicians and researchers with a brief overview of the current state of research regarding the use of CPM in children and adolescents, both healthy and clinical patients. The implications of CPM in experimental and clinical settings and its potential to aid in refining considerations to individualize treatment of pediatric pain syndromes will be discussed. KEYWORDS: chronic pain; conditioned pain modulation; descending endogenous pain inhibition; pediatrics PDF Safe Anaesthesia Worldwide Delivering safe anaesthesia to the world's poorest people Informes / Information World Congress on Regional Anesthesia & Pain Medicine April 19-21, 2018, New York City, USA Informes / Information

Anestesiología y Medicina del Dolor 52 664 6848905 vwhizar@anestesia-dolor.org anestesia-dolor.org

Sistema glimfático cerebral / The brain glymphatic system

Enero 21, 2018. No. 2970

El sistema glimfático cerebral fue descrito por Maiken Nedergaard, y nombrado así por la participación de la neuroglia. Los descubrimientos han demostrado que es una vía peri vascular de eliminación de productos metabólicos del cerebro (función pseudolinfática) en el cual los astrocitos juegan un papel vital. Se le ha relacionado con la fisiología cerebral y algunas enfermedades del SNC y la posibilidad de manipularlo con efectos terapéuticos que sin duda pronto estaremos utilizando en clínica. Hoy y mañana enviaremos información disponible con acceso abierto sobre este interesante tópico. The glymphatic system was described by Maiken Nedergaard, and named for the participation of the neuroglia. The discoveries have shown that it is a peri-vascular pathway for the elimination of metabolic products from the brain (pseudolymphatic function), in which astrocytes play a vital role. It has been related to brain physiology and some CNS diseases, and the possibility of manipulating it with therapeutic effects that we will soon be using in the clinic. Today and tomorrow we will send information available with open access on this interesting topic. ¿Hay un sistema linfático cerebral? Is there a cerebral lymphatic system? Iliff JJ1, Nedergaard M. Stroke. 2013 Jun;44(6 Suppl 1):S93-5. doi: 10.1161/STROKEAHA.112.678698. PDF El camino paravascular para la eliminación de desechos cerebrales: comprensión actual, importancia y controversia. The Paravascular Pathway for Brain Waste Clearance: Current Understanding, Significance and Controversy. Bacyinski A1, Xu M2, Wang W2, Hu J3. Author information Front Neuroanat. 2017 Nov 7;11:101. doi: 10.3389/fnana.2017.00101. eCollection 2017. Abstract The paravascular pathway, also known as the "glymphatic" pathway, is a recently described system for waste clearance in the brain. According to this model, cerebrospinal fluid (CSF) enters the paravascular spaces surrounding penetrating arteries of the brain, mixes with interstitial fluid (ISF) and solutes in the parenchyma, and exits along paravascular spaces of draining veins. Studies have shown that metabolic waste products and solutes, including proteins involved in the pathogenesis of neurodegenerative diseases such as amyloid-beta, may be cleared by this pathway. Consequently, a growing body of research has begun to explore the association between glymphatic dysfunction and various disease states. However, significant controversy exists in the literature regarding both the direction of waste clearance as well as the anatomical space in which the waste-fluid mixture is contained. Some studies have found no evidence of interstitial solute clearance along the paravascular space of veins. Rather, they demonstrate a perivascular pathway in which waste is cleared from the brain along an anatomically distinct perivascular space in a direction opposite to that of paravascular flow. Although possible explanations have been offered, none have been able to fully reconcile the discrepancies in the literature, and many questions remain. Given the therapeutic potential that a comprehensive understanding of brain waste clearance pathways might offer, further research and clarification is highly warranted. KEYWORDS: amyloid-beta; brain waste clearance; glymphatic system; paravascular pathway; perivascular pathway PDF Comprendiendo las funciones y relaciones del sistema glimfático y linfático meníngeo. Understanding the functions and relationships of the glymphatic system and meningeal lymphatics. Louveau A1, Plog BA2, Antila S3, Alitalo K3, Nedergaard M2,4, Kipnis J1. Author information J Clin Invest. 2017 Sep 1;127(9):3210-3219. doi: 10.1172/JCI90603. Epub 2017 Sep 1. Abstract Recent discoveries of the glymphatic system and of meningeal lymphatic vessels have generated a lot of excitement, along with some degree of skepticism. Here, we summarize the state of the field and point out the gaps of knowledge that should be filled through further research. We discuss the glymphatic system as a system that allows CNS perfusion by the cerebrospinal fluid (CSF) and interstitial fluid (ISF). We also describe the recently characterized meningeal lymphatic vessels and their role in drainage of the brain ISF, CSF, CNS-derived molecules, and immune cells from the CNS and meninges to the peripheral (CNS-draining) lymph nodes. We speculate on the relationship between the two systems and their malfunction that may underlie some neurological diseases. Although much remains to be investigated, these new discoveries have changed our understanding of mechanisms underlying CNS immune privilege and CNS drainage. Future studies should explore the communications between the glymphatic system and meningeal lymphatics in CNS disorders and develop new therapeutic modalities targeting these systems. PDF Safe Anaesthesia Worldwide Delivering safe anaesthesia to the world's poorest people Informes / Information World Congress on Regional Anesthesia & Pain Medicine April 19-21, 2018, New York City, USA Informes / Information

Anestesiología y Medicina del Dolor 52 664 6848905 vwhizar@anestesia-dolor.org anestesia-dolor.org

El sistema glimfático / The glymphatic system

Enero 22, 2018. No. 2971

El sistema glimfático: una guía para principiantes. El sistema glimfático es un sistema de eliminación de residuos macroscópico recientemente descubierto que utiliza un sistema único de túneles perivasculares, formado por células astrogliales, para promover la eliminación eficiente de proteínas solubles y metabolitos del sistema nervioso central. Además de la eliminación de desechos, el sistema glimfático también facilita la distribución de varios compuestos en el cerebro, incluyendo glucosa, lípidos, aminoácidos, factores de crecimiento y neuromoduladores. Curiosamente, el sistema glimfático funciona principalmente durante el sueño y se desconecta en gran medida durante la vigilia. La necesidad biológica de dormir en todas las especies puede por lo tanto reflejar que el cerebro debe entrar en un estado de actividad que permita la eliminación de productos de desecho potencialmente neurotóxicos, incluido el β-amiloide. Dado que el concepto del sistema glimfático es relativamente nuevo, revisaremos aquí sus elementos estructurales básicos, organización, regulación y funciones. También discutiremos los estudios recientes que indican que la función glimfatica se suprime en varias enfermedades y que la falla de la función glimfatica a su vez puede contribuir a la patología en trastornos neurodegenerativos, lesión cerebral traumática y apoplejía. The Glymphatic System: A Beginner's Guide. Jessen NA1, Munk AS2, Lundgaard I2, Nedergaard M2. Author information Neurochem Res. 2015 Dec;40(12):2583-99. doi: 10.1007/s11064-015-1581-6. Epub 2015 May 7. Abstract The glymphatic system is a recently discovered macroscopic waste clearance system that utilizes a unique system of perivascular tunnels, formed by astroglial cells, to promote efficient elimination of soluble proteins and metabolites from the central nervous system. Besides waste elimination, the glymphatic system also facilitates  brain-wide distribution of several compounds, including glucose, lipids, amino acids, growth factors, and neuromodulators. Intriguingly, the glymphatic system function mainly during sleep and is largely disengaged during wakefulness. The biological need for sleep across all species may therefore reflect that the brain must enter a state of activity that enables elimination of potentially neurotoxic waste products, including β-amyloid. Since the concept of the glymphatic system is relatively new, we will here review its basic structural elements, organization, regulation, and functions. We will also discuss recent studies indicating that glymphatic function is suppressed in various diseases and that failure of glymphatic function in turn might contribute to pathology in neurodegenerative disorders, traumatic brain injury and stroke. KEYWORDS: Aging; Astrocytes; Cerebrospinal fluid secretion; Neurodegenerative diseases; Perivascular spaces; Sleep; The glymphatic system; Traumatic brain injury; Virchow-Robin spaces PDF La anestesia general inhibe la actividad del sistema glimfático General Anesthesia Inhibits the Activity of the "Glymphatic System". Gakuba C1,2, Gaberel T1,3, Goursaud S1,2, Bourges J1,2, Di Palma C1,3, Quenault A1, de Lizarrondo SM1, Vivien D1,4, Gauberti M1,5. Author information Theranostics. 2018 Jan 1;8(3):710-722. doi: 10.7150/thno.19154. eCollection 2018. Abstract INTRODUCTION: According to the "glymphatic system" hypothesis, brain waste clearance is mediated by a continuous replacement of the interstitial milieu by a bulk flow of cerebrospinal fluid (CSF). Previous reports suggested that this cerebral CSF circulation is only active during general anesthesia or sleep, an effect mediated by the dilatation of the extracellular space. Given the controversies regarding the plausibility of this phenomenon and the limitations of currently available methods to image the glymphatic system, we developed original whole-brain in vivo imaging methods to investigate the effects of general anesthesia on the brain CSF circulation. METHODS: We used magnetic resonance imaging (MRI) and near-infrared fluorescence imaging (NIRF) after injection of a paramagnetic contrast agent or a fluorescent dye in the cisterna magna, in order to investigate the impact of general anesthesia (isoflurane, ketamine or ketamine/xylazine) on the intracranial CSF circulation in mice. RESULTS:In vivo imaging allowed us to image CSF flow in awake and anesthetized mice and confirmed the existence of a brain-wide CSF circulation. Contrary to what was initially thought, we demonstrated that the parenchymal CSF circulation is mainly active during wakefulness and significantly impaired during general anesthesia. This effect was especially significant when high doses of anesthetic agent were used (3% isoflurane). These results were consistent across the different anesthesia regimens and imaging modalities. Moreover, we failed to detect a significant change in the brain extracellular water volume using diffusion weighted imaging in awake and anesthetized mice. CONCLUSION: The parenchymal diffusion of small molecular weight compounds from the CSF is active during wakefulness. General anesthesia has a negative impact on the intracranial CSF circulation, especially when using a high dose of anesthetic agent. KEYWORDS: Alzheimer; anesthesia; choroid plexus.; glymphatic system; magnetic resonance imaging PDF La interferencia del sistema glimfático como mediador del trauma cerebral y la encefalopatía traumática crónica. Glymphatic system disruption as a mediator of brain trauma and chronic traumatic encephalopathy. Sullan MJ1, Asken BM2, Jaffee MS3, DeKosky ST4, Bauer RM5. Author information Neurosci Biobehav Rev. 2018 Jan;84:316-324. doi: 10.1016/j.neubiorev.2017.08.016. Epub 2017 Aug 30. Abstract Traumatic brain injury (TBI) is an increasingly important issue among veterans, athletes and the general public. Difficulties with sleep onset and maintenance are among the most commonly reported symptoms following injury, and sleep debt is associated with increased accumulation of beta amyloid (Aβ) and phosphorylated tau (p-tau) in the interstitial space. Recent research into the glymphatic system, a lymphatic-like metabolic clearance mechanism in the central nervous system (CNS) which relies on cerebrospinal fluid (CSF), interstitial fluid (ISF), and astrocytic processes, shows that clearance is potentiated during sleep. This system is damaged in the acute phase following mTBI, in part due to re-localization of aquaporin-4 channels away from astrocytic end feet, resulting in reduced potential for waste removal. Long-term consequences of chronic dysfunction within this system in the context of repetitive brain trauma and insomnia have not been established, but potentially provide one link in the explanatory chain connecting repetitive TBI with later neurodegeneration. Current research has shown p-tau deposition in perivascular spaces and along interstitial pathways in chronic traumatic encephalopathy (CTE), pathways related to glymphatic flow; these are the main channels by which metabolic waste is cleared. This review addresses possible links between mTBI-related damage to glymphatic functioning and physiological changes found in CTE, and proposes a model for the mediating role of sleep disruption in increasing the risk for developing CTE-related pathology and subsequent clinical symptoms following repetitive brain trauma. KEYWORDS: Aquaporin 4; Chronic traumatic encephalopathy; Glymphatic system; Insomnia; Sleep; Traumatic brain injury PDF Safe Anaesthesia Worldwide Delivering safe anaesthesia to the world's poorest people Informes / Information World Congress on Regional Anesthesia & Pain Medicine April 19-21, 2018, New York City, USA Informes / Information

Anestesiología y Medicina del Dolor 52 664 6848905 vwhizar@anestesia-dolor.org anestesia-dolor.org

Flexoelectricidad en huesos

http://www.artroscopiayreemplazos.com.mx/academia/flexoelectricidad-en-huesos/

Flexoelectricity in Bones.

Fuente

Este artículo es originalmente publicado en:

https://www.ncbi.nlm.nih.gov/pubmed/29345377

http://onlinelibrary.wiley.com/doi/10.1002/adma.201705316/abstract;jsessionid=F38FEA628757A858239DC2AF20E3ED8B.f02t01

De:

Vasquez-Sancho F1,2, Abdollahi A3, Damjanovic D4, Catalan G1,5.

Author information

1 Institut Català de Nanociencia i Nanotecnologia (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST), Campus UAB, Bellaterra, 08193, Barcelona, Catalonia, Spain.

2 Centro de Investigación en Ciencia e Ingeniería de Materiales (CICIMA), Universidad de Costa Rica, San José, 11501, Costa Rica.

3 Laboratori de Càlcul Numèric (LaCàN), Universitat Politècnica de Catalunya (UPC), Campus Nord UPC-C2, E-08034, Barcelona, Spain.

4 Ecole Politechnique Federale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland.

5 Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, E-08010, Barcelona, Catalonia, Spain.

Adv Mater. 2018 Jan 18. doi: 10.1002/adma.201705316. [Epub ahead of print]

Todos los derechos reservados para:

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Abstract

Bones generate electricity under pressure, and this electromechanical behavior is thought to be essential for bone’s self-repair and remodeling properties. The origin of this response is attributed to the piezoelectricity of collagen, which is the main structural protein of bones. In theory, however, any material can also generate voltages in response to strain gradients, thanks to the property known as flexoelectricity. In this work, the flexoelectricity of bone and pure bone mineral (hydroxyapatite) are measured and found to be of the same order of magnitude; the quantitative similarity suggests that hydroxyapatite flexoelectricity is the main source of bending-induced polarization in cortical bone. In addition, the measured flexoelectric coefficients are used to calculate the (flexo)electric fields generated by cracks in bone mineral. The results indicate that crack-generated flexoelectricity is theoretically large enough to induce osteocyte apoptosis and thus initiate the crack-healing process, suggesting a central role of flexoelectricity in bone repair and remodeling.

KEYWORDS:

bone remodeling; cracks; flexoelectricity; hydroxyapatite

Resumen

Los huesos generan electricidad bajo presión, y se considera que este comportamiento electromecánico es esencial para las propiedades de auto reparación y remodelación del hueso. El origen de esta respuesta se atribuye a la piezoelectricidad del colágeno, que es la principal proteína estructural de los huesos. En teoría, sin embargo, cualquier material también puede generar tensiones en respuesta a los gradientes de deformación, gracias a la propiedad conocida como flexoelectricidad. En este trabajo, se mide la flexoelectricidad del hueso y el mineral óseo puro (hidroxiapatita) y se encuentra que es del mismo orden de magnitud; la similitud cuantitativa sugiere que la flexoelectricidad de hidroxiapatita es la principal fuente de polarización inducida por flexión en el hueso cortical. Además, los coeficientes flexoeléctricos medidos se usan para calcular los campos eléctricos (flexo) generados por las grietas en el mineral óseo. Los resultados indican que la flexoelectricidad generada por grietas es teóricamente lo suficientemente grande como para inducir la apoptosis de osteocitos y, por lo tanto, iniciar el proceso de curación de grietas, lo que sugiere un papel central de la flexoelectricidad en la reparación y remodelación óseas.

PALABRAS CLAVE:

remodelación ósea; grietas; flexoelectricidad; hidroxiapatita

PMID:  29345377    DOI:   10.1002/adma.201705316