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Int. j. morphol ; 41(1): 188-194, feb. 2023. ilus, tab
Article in English | LILACS | ID: biblio-1430540


SUMMARY: Microsurgical procedures are the treatment of choice of peripheral nerve injuries, but often fail to reach full functional recovery. Melatonin has neuroprotective actions and might be used as a possible proregenerative pharmacological support. Therefore, the aim of this study was to analyze the time-dependence of the neuroprotective effect of melatonin on the overall fascicular structures of both ends of the transected nerve. Sciatic nerve transection was performed in 34 adult male Wistar rats divided in four groups: two vehicle groups (N=7) treated intraperitoneally for 7 (V7) or 21 (V21) consecutive days with vehicle (5 % ethanol in Ringer solution) and two melatonin groups (N=10) administered intraperitoneally 30 mg/kg of melatonin for 7 (M7) or 21 (M21) consecutive days. At the end of the experiment, proximal stump neuroma and distal stump fibroma were excised and processed for qualitative and quantitative histological analysis. Intrafascicular neural structures were better preserved and the collagen deposition was reduced in the melatonin treated groups than in the vehicle groups. Myelin sheath regeneration observed through its thickness measurement was statistically significantly (p<0,05) more pronounced in the M21 (1,23±0,18 µm) vs. V21 group (0,98±0,13 µm). The mean volume density of the endoneurium was lower in both melatonin treated groups in comparison to the matching vehicle treated groups. Although not statistically different, the endoneural tube diameter was larger in both melatonin groups vs. vehicle groups, and the effect of melatonin was more pronounced after 21 days (24,97 % increase) vs. 7 days of melatonin treatment (18,8 % increase). Melatonin exerts a time-dependent proregenerative effect on nerve fibers in the proximal stump and an anti-scarring effect in both stumps.

Los procedimientos microquirúrgicos son el tratamiento de elección de las lesiones de los nervios periféricos, pero a menudo no logran una recuperación funcional completa. La melatonina tiene acciones neuroprotectoras y podría ser utilizada como un posible apoyo farmacológico proregenerativo. Por lo tanto, el objetivo de este estudio fue analizar la dependencia del tiempo del efecto neuroprotector de la melatonina sobre las estructuras fasciculares generales de ambos extremos del nervio seccionado. La sección del nervio ciático se realizó en 34 ratas Wistar macho adultas divididas en cuatro grupos: dos grupos de vehículo (N=7) tratados por vía intraperitoneal durante 7 (V7) o 21 (V21) días consecutivos con vehículo (5 % de etanol en solución Ringer) y dos grupos grupos de melatonina (N=10) a los que se les administró por vía intraperitoneal 30 mg/kg de melatonina durante 7 (M7) o 21 (M21) días consecutivos. Al final del experimento, se extirparon y procesaron el neuroma del muñón proximal y el fibroma del muñón distal del nervio para un análisis histológico cualitativo y cuantitativo. Las estructuras neurales intrafasciculares se conservaron mejor y el depósito de colágeno se redujo en los grupos tratados con melatonina respecto a los grupos con vehículo. La regeneración de la vaina de mielina observada a través de la medición de su espesor fue estadísticamente significativa (p<0,05) más pronunciada en el grupo M21 (1,23±0,18 µm) vs V21 (0,98±0,13 µm). La densidad de volumen media del endoneuro fue menor en ambos grupos tratados con melatonina en comparación con los grupos tratados con vehículo equivalente. Aunque no fue estadísticamente diferente, el diámetro del tubo endoneural fue mayor en ambos grupos de melatonina frente a los grupos de vehículo, y el efecto de la melatonina fue más pronunciado después de 21 días (aumento del 24,97 %) frente a los 7 días de tratamiento con melatonina (18,8 % de aumento). La melatonina ejerce un efecto proregenerativo dependiente del tiempo sobre las fibras nerviosas del muñón proximal y un efecto anticicatricial en ambos muñones.

Animals , Male , Rats , Sciatic Nerve/drug effects , Melatonin/pharmacology , Nerve Regeneration/drug effects , Peripheral Nerves , Sciatic Nerve/physiology , Time Factors , Rats, Wistar , Myelin Sheath/drug effects , Nerve Regeneration/physiology
Neuroscience Bulletin ; (6): 541-552, 2023.
Article in English | WPRIM | ID: wpr-971571


Astrocytes (ASTs) and oligodendroglial lineage cells (OLGs) are major macroglial cells in the central nervous system. ASTs communicate with each other through connexin (Cx) and Cx-based network structures, both of which allow for quick transport of nutrients and signals. Moreover, ASTs interact with OLGs through connexin (Cx)-mediated networks to modulate various physiological processes in the brain. In this article, following a brief description of the infrastructural basis of the glial networks and exocrine factors by which ASTs and OLGs may crosstalk, we focus on recapitulating how the interactions between these two types of glial cells modulate myelination, and how the AST-OLG interactions are involved in protecting the integrity of the blood-brain barrier (BBB) and regulating synaptogenesis and neural activity. Recent studies further suggest that AST-OLG interactions are associated with myelin-related diseases, such as multiple sclerosis. A better understanding of the regulatory mechanisms underlying AST-OLG interactions may inspire the development of novel therapeutic strategies for related brain diseases.

Humans , Myelin Sheath , Astrocytes , Oligodendroglia , Brain , Brain Diseases
Neuroscience Bulletin ; (6): 453-465, 2023.
Article in English | WPRIM | ID: wpr-971570


Myelin-forming oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system (PNS) are essential for structural and functional homeostasis of nervous tissue. Albeit with certain similarities, the regulation of CNS and PNS myelination is executed differently. Recent advances highlight the coordinated regulation of oligodendrocyte myelination by amino-acid sensing and growth factor signaling pathways. In this review, we discuss novel insights into the understanding of differential regulation of oligodendrocyte and Schwann cell biology in CNS and PNS myelination, with particular focus on the roles of growth factor-stimulated RHEB-mTORC1 and GATOR2-mediated amino-acid sensing/signaling pathways. We also discuss recent progress on the metabolic regulation of oligodendrocytes and Schwann cells and the impact of their dysfunction on neuronal function and disease.

Amino Acids , Myelin Sheath/metabolism , Schwann Cells/metabolism , Oligodendroglia/metabolism , Signal Transduction , Intercellular Signaling Peptides and Proteins/metabolism
China Journal of Chinese Materia Medica ; (24): 5-12, 2023.
Article in Chinese | WPRIM | ID: wpr-970495


Multiple sclerosis(MS) shows the pathological characteristics of "inflammatory injury of white matter" and "myelin repair disability" in the central nervous system(CNS). It is very essential for MS treatment and reduction of disease burden to strengthen repair, improve function, and reduce disability. Accordingly, different from the simple immunosuppression, we believe that key to strengthening remyelination and maintaining the "damage-repair" homeostasis of tissue is to change the current one-way immunosuppression strategy and achieve the "moderate pro-inflammation-effective inflammation removal" homeostasis. Traditional Chinese medicine shows huge potential in this strategy. Through literature research, this study summarized the research on remyelination, discussed the "mode-rate pro-inflammation-effective inflammation removal" homeostasis and the "damage-repair" homeostasis based on microglia, and summed up the key links in remyelination in MS. This review is expected to lay a theoretical basis for improving the function of MS patients and guide the application of traditional Chinese medicine.

Humans , Multiple Sclerosis/pathology , Remyelination/physiology , Myelin Sheath/pathology , Inflammation/drug therapy , Homeostasis
Rev. bras. oftalmol ; 81: e0038, 2022. graf
Article in English | LILACS | ID: biblio-1376777


ABSTRACT Myelinated retinal nerve fibers are rare congenital anomalies that appear as gray-white patches. They may be present in a syndrome characterized by ipsilateral myelinated retinal nerve fibers, myopia and amblyopia. The author reported an ellipsoid zone defect on spectral domain optical coherence tomography in a case of Straatsma syndrome without macular extension.

RESUMO Fibras nervosas retinais mielinizadas são anomalias congênitas raras que aparecem como manchas branco-acinzentadas. Eles podem se apresentar em uma síndrome caracterizada por fibras nervosas retinais mielinizadas ipsilaterais, miopia e ambliopia. O autor relatou um defeito na zona elipsoide na tomografia de coerência óptica de domínio espectral em um caso de síndrome de Straatsma sem extensão macular.

Humans , Female , Adolescent , Retinal Diseases/pathology , Retinal Diseases/diagnostic imaging , Nerve Fibers/pathology , Nerve Fibers, Myelinated/pathology , Optic Disk , Amblyopia , Eye Abnormalities/diagnostic imaging , Tomography, Optical Coherence , Fundus Oculi , Myelin Sheath , Myopia
Neuroscience Bulletin ; (6): 720-740, 2022.
Article in English | WPRIM | ID: wpr-939842


Enhancing remyelination after injury is of utmost importance for optimizing the recovery of nerve function. While the formation of myelin by Schwann cells (SCs) is critical for the function of the peripheral nervous system, the temporal dynamics and regulatory mechanisms that control the progress of the SC lineage through myelination require further elucidation. Here, using in vitro co-culture models, gene expression profiling of laser capture-microdissected SCs at various stages of myelination, and multilevel bioinformatic analysis, we demonstrated that SCs exhibit three distinct transcriptional characteristics during myelination: the immature, promyelinating, and myelinating states. We showed that suppressor interacting 3a (Sin3A) and 16 other transcription factors and chromatin regulators play important roles in the progress of myelination. Sin3A knockdown in the sciatic nerve or specifically in SCs reduced or delayed the myelination of regenerating axons in a rat crushed sciatic nerve model, while overexpression of Sin3A greatly promoted the remyelination of axons. Further, in vitro experiments revealed that Sin3A silencing inhibited SC migration and differentiation at the promyelination stage and promoted SC proliferation at the immature stage. In addition, SC differentiation and maturation may be regulated by the Sin3A/histone deacetylase2 (HDAC2) complex functionally cooperating with Sox10, as demonstrated by rescue assays. Together, these results complement the recent genome and proteome analyses of SCs during peripheral nerve myelin formation. The results also reveal a key role of Sin3A-dependent chromatin organization in promoting myelinogenic programs and SC differentiation to control peripheral myelination and repair. These findings may inform new treatments for enhancing remyelination and nerve regeneration.

Animals , Rats , Axons , Chromatin/metabolism , Gene Expression Profiling , Myelin Sheath/metabolism , Nerve Regeneration/physiology , Schwann Cells/metabolism , Sciatic Nerve/injuries
Chinese Journal of Contemporary Pediatrics ; (12): 711-716, 2022.
Article in Chinese | WPRIM | ID: wpr-939652


Leukodystrophy (LD) is a group of genetic heterogeneous diseases characterized by primary abnormalities in glial cells and myelin sheath, and it is a common nervous system disease in children and has significant genotype-phenotype correlation. In recent years, the improvement in high-throughput sequencing has changed the diagnostic and therapeutic mode of LD, and elaborative phenotype analysis, such as the collection of natural history and multimodal neuroimaging evaluation during development, also provides important information for subsequent genetic diagnosis. This article reviews LD from the perspective of clinical genetics, in order to improve the awareness of this disease among pediatricians in China.

Humans , Demyelinating Diseases , High-Throughput Nucleotide Sequencing , Myelin Sheath , Neurodegenerative Diseases , Phenotype
Int. j. morphol ; 39(1): 179-185, feb. 2021. ilus
Article in English | LILACS | ID: biblio-1385323


SUMMARY: Despite the existence of a large amount of actin in the axons, the concentration F-actin was quite low in the myelinated axons and almost all the F-actin were located in the peripheries of the myelinated axons. Until now, the ultrastructural localization of F-actin has still not been reported in the myelinated axons, probably due to the lack of an appropriate detection method. In the present study, a phalloidin-based FITC-anti-FITC technique was adopted to investigate the subcellular localization of F-actin in the myelinated axons. By using this technique, F-actin is located in the outer and inner collars of myelinated cytoplasm surrounding the intermodal axon, the Schmidt-Lanterman incisures, the paranodal terminal loops and the nodal microvilli. In addition, the satellite cell envelope, which encapsulates the axonal initial segment of the peripheral sensory neuron, was also demonstrated as an F-actin-enriched structure. This study provided a hitherto unreported ultrastructural view of the F-actin in the myelinated axons, which may assist in understanding the unique organization of axonal actin cytoskeleton.

RESUMEN: A pesar de la existencia de una gran cantidad de actina en los axones, la concentración de F-actina era bastante baja en los axones mielinizados y casi la totalidad de F-actina se localizaba en las periferias de los axones mielinizados. A la fecha aún no se ha reportado la localización ultraestructural de F-actina en los axones mielinizados, probablemente debido a la falta de un método de detección apropiado. En el presente estudio, se adoptó una técnica FITC-anti-FITC basada en faloidina para investigar la localización subcelular de F-actina en los axones mielinizados. Mediante el uso de esta técnica, la F-actina se localiza en los collares externo e interno del citoplasma mielinizado que rodea el axón intermodal, a las incisiones de Schmidt-Lanterman,a las asas terminales paranodales y a las microvellosidades nodales. Además, la envoltura de la célula satélite, que encapsula el segmento axonal inicial de la neurona sensorial periférica, también se demostró como una estructura enriquecida con F-actina. Este estudio proporcionó una vista ultraestructural de la F-actina en los axones mielinizados, que puede ayudar a comprender la organización única del citoesqueleto de actina axonal.

Animals , Female , Rats , Axons/ultrastructure , Actins/ultrastructure , Myelin Sheath/ultrastructure , Microscopy, Electron
Clinics ; 76: e2167, 2021. tab, graf
Article in English | LILACS | ID: biblio-1249576


OBJECTIVES: Leukoaraiosis is described as white matter lesions that are associated with cognitive dysfunction, neurodegenerative disorders, etc. Myelin depletion is a salient pathological feature of, and the loss of oligodendrocytes is one of the most robust alterations evident in, white matter degeneration. Recent studies have revealed that claudin proteins are aberrantly expressed in leukoaraiosis and regulate oligodendrocyte activity. However, the roles of claudin-1 and claudin-3 in oligodendrocytes and leukoaraiosis are still not well-defined. METHODS: Quantitative polymerase chain reaction was used to measure the expression of claudin-1 (CLDN1), claudin-3 (CLDN3), and myelinogenesis-related genes such as myelin basic protein (MBP), proteolipid protein (PLP), oligodendrocyte transcription factor 2 (OLIG2), and SRY-box transcription factor 10 (SOX10) in leukoaraiosis patients (n=122) and healthy controls (n=122). The expression of claudin-1 and claudin-3 was either ectopically silenced or augmented in Oli-neu oligodendrocytes, and colony formation, apoptosis, and migration assays were performed. Finally, the expression of myelin proteins was evaluated by western blotting. RESULTS: Our results revealed that in addition to SOX10, the expression levels of claudin-1, claudin-3, and myelinogenesis-related proteins were prominently downregulated in leukoaraiosis patients, compared to those in healthy controls. Furthermore, the growth and migration of Oli-neu cells were downregulated upon silencing claudin-1 or claudin-3. However, the overexpression of claudin-1 or claudin-3 resulted in the reduction of the degree of apoptosis in Oli-neu cells. In addition, claudin-1 and claudin-3 promoted the expression of MBP, OLIG2, PLP, and SOX10 at the translational level. CONCLUSION: Our data has demonstrated that the abnormal expression of claudin-1 and claudin-3 regulates the pathological progression of leukoaraiosis by governing the viability and myelination of oligodendrocytes. These findings provide novel insights into the regulatory mechanisms underlying the roles of claudin-1 and claudin-3 in leukoaraiosis.

Humans , Leukoaraiosis , Oligodendroglia , Claudin-1 , Claudin-3/genetics , Myelin Sheath
Chinese Journal of Contemporary Pediatrics ; (12): 410-415, 2021.
Article in Chinese | WPRIM | ID: wpr-879868


OBJECTIVE@#To study the effect of human oligodendrocyte precursor cell (hOPC) transplantation in the treatment of white matter injury (WMI).@*METHODS@#Neonatal rats were randomly divided into a sham-operation group, a model group, and a transplantation group (@*RESULTS@#The place navigation test using the Morris water maze showed that the model group had a significantly longer escape latency than the sham-operation group, and compared with the model group, the transplantation group had a significant reduction in escape latency (@*CONCLUSIONS@#Intrathecal hOPC transplantation may alleviate neurological injury and promote remyelination in a rat model of WMI.

Animals , Humans , Rats , Animals, Newborn , Myelin Sheath , Oligodendrocyte Precursor Cells , Oligodendroglia , White Matter
Neuroscience Bulletin ; (6): 1397-1411, 2021.
Article in English | WPRIM | ID: wpr-922649


Exposure to chronic hypoxia is considered to be a risk factor for deficits in brain function in adults, but the underlying mechanisms remain largely unknown. Since active myelinogenesis persists in the adult central nervous system, here we aimed to investigate the impact of chronic hypoxia on myelination and the related functional consequences in adult mice. Using a transgenic approach to label newly-generated myelin sheaths (NG2-CreER

Animals , Mice , Clemastine , Hypoxia/complications , Mice, Inbred C57BL , Mice, Transgenic , Myelin Sheath , Oligodendroglia
Neuroscience Bulletin ; (6): 1314-1324, 2021.
Article in English | WPRIM | ID: wpr-922627


The exacerbation of progressive multiple sclerosis (MS) is closely associated with obstruction of the differentiation of oligodendrocyte progenitor cells (OPCs). To discover novel therapeutic compounds for enhancing remyelination by endogenous OPCs, we screened for myelin basic protein expression using cultured rat OPCs and a library of small-molecule compounds. One of the most effective drugs was pinocembrin, which remarkably promoted OPC differentiation and maturation without affecting cell proliferation and survival. Based on these in vitro effects, we further assessed the therapeutic effects of pinocembrin in animal models of demyelinating diseases. We demonstrated that pinocembrin significantly ameliorated the progression of experimental autoimmune encephalomyelitis (EAE) and enhanced the repair of demyelination in lysolectin-induced lesions. Further studies indicated that pinocembrin increased the phosphorylation level of mammalian target of rapamycin (mTOR). Taken together, our results demonstrated that pinocembrin promotes OPC differentiation and remyelination through the phosphorylated mTOR pathway, and suggest a novel therapeutic prospect for this natural flavonoid product in treating demyelinating diseases.

Animals , Mice , Rats , Cell Differentiation , Flavanones , Mice, Inbred C57BL , Myelin Sheath/metabolism , Oligodendroglia/metabolism , Remyelination , Signal Transduction , TOR Serine-Threonine Kinases/metabolism
Int. j. morphol ; 38(6): 1606-1613, Dec. 2020. tab, graf
Article in English | LILACS | ID: biblio-1134486


SUMMARY: Disturbances of sensory and motor nerve conduction velocity in the spinal cord as well as degenerated myelin sheaths are observed in diabetic patients and animal models. Indeed, oligodendrocytes (OLs), which are important neuroglial cells, generate myelin in the central nervous system. Spinal enlargement, including cervical and lumbar enlargements, innervates all limbs. Thus, the purposes of this study were to examine and compare the ultrastructural alterations of OLs in spinal enlargements of streptozotocin (STZ)- induced diabetic rats and controls. Thirteen male Sprague-Dawley rats were induced with STZ in citrate buffer and six control rats were injected with the same buffer solution. All rats were sacrificed after inductions at four (short-term DM) and twenty-four weeks (long-term DM). The selected spinal enlargements were processed for transmission electron microscopy. The OL alterations in both the cervical and lumbar enlargements were apparently the same. In short-term DM, the nuclei of OLs became swelled with chromatin clumping. Cytoplasmic organelles were moderately damaged. In long-term DM, OLs contained shrinkage nuclei with thick heterochromatin clumping. Severely degenerated mitochondria with disrupted cristae and broken membranes were observed. Moreover, distended and fragmented rough endoplasmic reticulum were observed, and large clear areas were present in the cytoplasm. Additionally, the loosening, splitting, and destruction of myelin lamellae were found. This study can provide important preliminary information about the alteration of OLs in the spinal cords of diabetic patients, which might be involve in the impairments of sensory and motor conduction velocities in these individuals.

RESUMEN: En pacientes diabéticos y modelos animales se observan alteraciones de la velocidad de conducción nerviosa sensorial y motora en la médula espinal, así como vainas de mielina degeneradas. De hecho, los oligodendrocitos (OL), que son importantes células neurogliales, generan mielina en el sistema nervioso central. La intumescencia espinal, a nivel cervical y lumbar, inerva los miembros. Por lo tanto, los propósitos de este estudio fueron examinar y comparar las alteraciones ultraestructurales de los OL en la intumescencia espinal de ratas diabéticas inducidas por estreptozotocina (STZ) y controles. Se indujeron trece ratas macho Sprague-Dawley con STZ en tampón citrato y se inyectaron seis ratas de control con la misma solución tampón. Todas las ratas se sacrificaron después de la inducción a las cuatro (DM a corto plazo) y a las veinticuatro semanas (DM a largo plazo). Las ampliaciones de la columna seleccionadas se procesaron para microscopía electrónica de transmisión. Las alteraciones de OL en las intumescencias cervical y lumbar eran aparentemente las mismas. En la DM a corto plazo, los núcleos de los OL se hincharon con la acumulación de cromatina. Los orgánulos citoplasmáticos sufrieron daños moderados. En la DM a largo plazo, los OL contenían núcleos de contracción con aglutinación de heterocromatina gruesa. Se observaron mitocondrias severamente degeneradas con crestas y membranas rotas. Además, se observó un retículo endoplásmico rugoso distendido y fragmentado, y estaban presentes grandes áreas claras en el citoplasma. Además, se encontraron el aflojamiento, la división y la destrucción de las laminillas de mielina. Este estudio puede proporcionar información preliminar importante sobre la alteración de los OL en la médula espinal de los pacientes diabéticos, que podría estar involucrada en las alteraciones de las velocidades de conducción sensorial y motora en estos individuos.

Animals , Male , Rats , Spinal Cord/pathology , Oligodendroglia/pathology , Diabetes Mellitus, Experimental/pathology , Spinal Cord/ultrastructure , Central Nervous System , Oligodendroglia/ultrastructure , Rats, Sprague-Dawley , Microscopy, Electron, Transmission , Myelin Sheath
Int. j. morphol ; 38(5): 1197-1200, oct. 2020. graf
Article in English | LILACS | ID: biblio-1134424


SUMMARY: Histological techniques are the study of animal and human tissues through staining and examining them under a microscope. To demonstrate the axonal degeneration and demyelination in histological studies, the Luxol Fast Blue staining is gold standard techniques. In this study, a new histochemical method based on modified Luxol Fast Blue for the staining of the myelin sheath in sciatic nerve tissues described. The sciatic nerves of rats were removed and then the sciatic nerve was immersed in 10 % formaldehyde for one week and embedded in paraffin block. Next, thin sections (5 µm) were cut, using a microtome and stained with conventional and modified Luxol Fast Blue. Our results showed that a new method of modified Luxol Fast Blue staining can accurately identify the myelin in the sciatic nerve fibers. The current study showed that the Luxol Fast Blue combination with Light Green has a good effect on myelin coloration, and the results of this study are comparable to LFB combination with Sirius red.

RESUMEN: Las técnicas histológicas son el estudio de tejidos animales y humanos mediante tinción y examen bajo un microscopio. Para demostrar la degeneración axonal y la desmielinización en estudios histológicos, la tinción Luxol Fast Blue es una técnica estándar de oro. En este estudio, se describe un nuevo método histoquímico basado en Luxol Fast Blue modificado para la tinción de mielina en los tejidos del nervio ciático. Se seccionaron los nervios ciáticos de ratas y luego el nervio ciático se sumergió en formaldehído al 10 % durante una semana y se fijó en bloque de parafina. Posteriormente, se cortaron secciones delgadas (5 µm) usando un microtomo y se tiñeron con Luxol Fast Blue convencional y modificado. Nuestros resultados mostraron que un nuevo método de tinción Luxol Fast Blue modificado puede identificar con precisión la mielina en las fibras del nervio ciático. El estudio actual mostró que la combinación Luxol Fast Blue con Light Green es un buen efecto sobre la coloración de mielina, y los resultados de este estudio son comparables a la combinación LFB con Sirius red.

Animals , Rats , Sciatic Nerve/anatomy & histology , Staining and Labeling/methods , Myelin Sheath , Paraffin , Histological Techniques , Formaldehyde , Microscopy/methods
Int. j. morphol ; 38(2): 505-512, abr. 2020. graf
Article in English | LILACS | ID: biblio-1056469


Sexual dimorphism exists at all levels of the nervous system. These sex differences could underlie genderrelated differences in behavior and neuropsychological function, as well as the gender differences in the prevalence of various mental disorders such as autism, attention deficit disorders, and schizophrenia. Myelination, on the other hand, is a unique cellular process that can have a dramatic impact on the structure and physiology of an axon and its surrounding tissue. The corpus callosum (CC) is the largest of the brain commissures, which connects the cerebral cortices of the two hemispheres, and provides interhemispheric connectivity for information transfer and processing between cortical regions. Variation in the axonal properties of CC will alter the interhemispheric connectivity. The CC consists of myelinated and unmyelinated axons, glial cells and blood vessels. Several functional studies have reported that the function of CC is associated with its axons density and myelination properties. The sexual dimorphism in the axonal content of the CC has always been controversial; hence, the aim of this study was to analyze the differences in axons' diameter and myelin sheath thickness of the CC between male and female rats. For this purpose, five pairs of adult male and female rats were perfused and the CC were removed and sectioned. Four sections from different subregions of the corpus callosum that represent the genu, anterior body, posterior body, and splenium of the CC were stained and electron microscopic images were captured using stereological guidelines. Later, the axons diameter and myelin sheath thickness for each subregion were calculated and compared between males and females. Our preliminary findings of the present study indicated region specific differences in the myelinated axon thickness and diameter in the CC between male and female rats.

El dimorfismo sexual existe en todos los niveles del sistema nervioso. Estas diferencias de sexo podrían ser la base de las diferencias de comportamiento y función neuropsicológica relacionadas con el sexo, así como las diferencias en la prevalencia de diversos trastornos mentales, como el autismo, los trastornos por déficit de atención y la esquizofrenia. La mielinización, por otro lado, es un proceso celular único que puede tener un impacto dramático en la estructura y fisiología de un axón y su tejido circundante. El cuerpo calloso (CC) es la mayor comisura cerebral, que conecta las cortezas cerebrales de ambos hemisferios, y proporciona la conectividad interhemisférica para la transferencia y el procesamiento de información entre regiones corticales. La variación en las propiedades axonales de CC alterará la conectividad interhemisférica. El CC consiste en axones mielinizados y no mielinizados, células gliales y vasos sanguíneos. Varios estudios funcionales han informado que la función de CC está asociada con la densidad de axones y las propiedades de mielinización. El dimorfismo sexual en el contenido axonal del CC siempre ha sido controvertido; por lo tanto, el objetivo de este estudio fue analizar las diferencias en el diámetro de los axones y el grosor de la vaina de mielina del CC entre ratas macho y hembra. Para este propósito, se perfundieron cinco pares de ratas macho y hembra adultas y se extrajeron y seccionaron las CC. Se tiñeron cuatro secciones de diferentes subregiones del cuerpo calloso que representan el genu, el cuerpo anterior, el cuerpo posterior y el esplenio y se capturaron imágenes de microscopía electrónicas utilizando referencias estereológicas. Posteriormente se calculó el diámetro de los axones y el grosor de la vaina de mielina para cada subregión y se compararon entre machos y hembras. Nuestros hallazgos preliminares del presente estudio indicaron diferencias específicas en el grosor y diámetro del axón mielinizado en el CC entre ratas macho y hembra.

Animals , Male , Female , Rats , Axons/ultrastructure , Sex Characteristics , Corpus Callosum/ultrastructure , Myelin Sheath/ultrastructure , Microscopy, Electron , Corpus Callosum/cytology
Rev. bras. oftalmol ; 79(1): 66-68, Jan.-Feb. 2020. graf
Article in English | LILACS | ID: biblio-1092650


Abstract The presence of retinal myelinated nerve fibers is not a rare finding during routine examinations, and it is usually a benign and isolated finding. However, in some rare cases, it can be associated with other ophthalmological conditions. We describe a case of a patient with the triad myelin nerve fibers, myopia and ambliopia, which configures the Straatsma Syndrome.

Resumo A presença de fibras de mielina é um achado comum durante exames oftalmológicos de rotina. Na maior parte das vezes, tem caráter beningno e é um achado isolado. No entanto, em alguns raros casos, a presença de mielinização pode estar associada a outras condições oftalmológicas. Descrevemos um caso de paciente com a tríade presença de fibras nervosas retinianas mielinizadas, miopia, e ambliopia, configurando a síndrome de Straatsma.

Humans , Female , Middle Aged , Retinal Diseases/diagnosis , Amblyopia/diagnosis , Myopia/diagnosis , Nerve Fibers, Myelinated/pathology , Ophthalmoscopy , Optic Nerve/abnormalities , Visual Acuity , Anisometropia , Tomography, Optical Coherence , Fundus Oculi , Myelin Sheath
Rev. colomb. anestesiol ; 47(3): 180-183, July-Sept. 2019.
Article in English | LILACS, COLNAL | ID: biblio-1020677


Abstract Introduction: It is uncommon to come across patients with neuromuscular diseases in the daily practice of anesthesia, given the low prevalence of those conditions. Charcot-Marie-Tooth (CMT) disease is the most frequently, caused by an inherited abnormal myelin structure pattern. In view of the low prevalence of this condition (1:25,000), there is little information, derived mostly from case reports, about the use of neuroaxial anesthesia in these patients. Case presentation: Description of a patient with underlying CMT disease compromising lower limb mobility, who comes to the emergency service due to lower limb pain. After being diagnosed with an acetabular fracture, the patient underwent orthopedic surgery under spinal anesthesia, selected based on patient comorbidities, and the immediate postoperative follow-up. Results: The anesthetic and surgical procedures proceeded uneventfully and no neuropathic worsening was observed during the next 24 hours. Conclusion: Uneventful neuroaxial anesthesia is reported in a patient with neuromuscular disease. The case contributes to show the benefits and safety of this form of anesthesia when compared with other options.

Resumen Introducción: En la práctica anestésica diaria es raro enfrentarse a pacientes con patologías neuromusculares, dada la poca pre-valencia de dichas patologías. La más frecuente de ellas es la enfermedad de Charcot-Marie-Tooth, en la cual se hereda un patrón alterado en la estructura de la mielina. Debido a la baja prevalencia de esta patología (1:25000), el uso de anestesia neuroaxial en dichos pacientes no cuenta con mucha información, y mucha de ella proviene de reportes de casos. Presentación del caso: Se describe el caso de un paciente con enfermedad de Charcot-Marie-Tooth, de base, con compromiso de la movilidad en miembros inferiores, y quien asiste a urgencias por dolor en miembro inferior. Tras ser diagnosticado con fractura de acetábulo, fue sometido a cirugía ortopédica bajo anestesia raquídea, indicada a la luz de sus comorbilidades, y el posterior seguimiento inmediato. Resultados: Se realiza el procedimiento anestésico y quirúrgico sin complicaciones, y no se presenta empeoramiento de la neuropatía en las 24 horas posteriores. Conclusiones: Se reporta un caso de anestesia neuroaxial en paciente con enfermedad neuromuscular sin incidencias, que ayuda así a ir mostrando los beneficios de la mencionada anestesia y su seguridad frente a otras opciones.

Humans , Male , Middle Aged , Charcot-Marie-Tooth Disease , Orthopedic Procedures , Anesthesia, Spinal , Surgical Procedures, Operative , Aftercare , Lower Extremity , Fractures, Bone , Acetabulum , Myelin Sheath , Neuromuscular Diseases
Saude e pesqui. (Impr.) ; 12(1): 97-106, jan.-abr. 2019. ilus
Article in Portuguese | LILACS | ID: biblio-995593


O objetivo deste trabalho é estudar a morfologia neuronal a partir de modelos animais, fornecer informações biológicas difíceis de serem obtidas em humanos, permitindo estudar condições neuropsiquiátricas como doença de Alzheimer, ansiedade, dentre outras. O presente trabalho descreveu metodologia de estudo para cérebro de roedores, duas técnicas neuroanatômicas, Klüver-Barrera e Golgi-Cox, e seus respectivos processos de quantificação. A técnica de Klüver-Barrera permitiu visualização da substância branca e cinzenta com destaque na bainha de mielina. A técnica de Golgi-Cox, adaptada para realidade de nosso laboratório, mostrou-se eficiente para visualização de neurônios e seus prolongamentos, como dendritos e espinhas dendríticas, permitindo assim a quantificação. A partir de imagens obtidas de microscópio descreveu-se os diferentes passos para quantificação, a determinação de volume de estruturas internas cerebrais (corpo caloso e camada celular do hipocampo) assim como a quantificação das espinhas dendríticas em neurônios piramidais. Os métodos descritos e detalhados poderão ser utilizados em vários campos da neurociência

Neuronal morphology is analyzed in animal models to provide biological information difficult to obtain in humans. The above makes possible the study of neuro-psychiatric, such as Alzheimer´s disease, anxiety and others. Current study described methodology for rodents´ brains, two neuro-anatomic techniques, Klüver-Barrera and Golgi-Cox, and their respective quantification processes. Klüver-Barrera technique visualized the white and gray matter, particularly the myelin sheath. Golgi-Cox technique, adapted for current research, was efficient to visualize neurons and their prolongations, such as dendrites and dendritic spines, with quantification. Images by microscope described the different steps for the quantification, determination of volume of the brain´s internal structures (callous body and the hypocampus´s cell layer) coupled to the quantification of dendritic spines in pyramid neurons. Described and detailed methods will be useful in several fields of neuroscience

Animals , Central Nervous System , Dendritic Spines , Myelin Sheath , Neurosciences
Rev chil anest ; 48(1): 57-61, 2019. ilus, tab
Article in Spanish | LILACS | ID: biblio-1451540


Intracranial pressure (ICP) is a parameter of high clinical relevance. Today invasive methods are reference for its measurement. The diameter of the optic nerve sheath (NOSD) is influenced by changes in ICP. A NOSD higher than 5 mm is well correlated with a ICP over 20 mmHg. OBJECTIVE: To evaluate the feasibility in measuring NOSD by ultrasound (ECO) made by an anesthesiologist. The secondary objective is to assess the impact of the Trendelenburg position in the NOSD. MATERIAL AND METHODS: A descriptive study was carried out between April-September 2014, with the participation of 89 volunteers, ages 20 to 39 years old, 49 men, without fasting, with defined inclusion criteria to ensure absence of underlying disease, chronic drugs intake and normovolemic state. After application of gel, a linear transducer (10-15 MHz) was positioned on the eyeball to measure the NOSD; measurements were performed with 0º tilt and then after five minutes in 45º. Statistical analysis was performed with STATA 10.0, with p-value < 0,05 for statistical significance. RESULTS: The procedure was well tolerated. Echocardiograph windows obtained allowed measurements in all cases with an average NOSD of 2.3 ± 6 mm at 0º and 2,4 ± 0,8 mm at 45º (p = 67). CONCLUSION: In this group of patients, young, healthy, without underlying disease, not undergoing anesthesia and outside the operating room, the use of ocular ECO allowed measurements of DVNO in a simple and reproducible way, without adverse effects. The existence of this tool, that estimates the PIC indirectly, is of great anesthesiology utility.

La presión intracraneal (PIC) es un parámetro de alta relevancia clínica. En la actualidad los métodos invasivos son su referencia para medición. El diámetro de la vaina del nervio óptico (DVNO) medida con ecografía se ve influenciado por cambios en la PIC. Se ha demostrado que el DVNO superior a 5 mm se correlaciona con PIC mayor que 20 mmHg. OBJETIVO: Evaluar la factibilidad en la medición del DVNO mediante ecografía (ECO) realizada por anestesiólogos. Como objetivo secundario, evaluar el impacto de la posición de Trendelenburg (PT) en el DVNO. MATERIAL Y MÉTODOS: Se realizó estudio descriptivo, entre abril-octubre 2014, con la participación de 89 voluntarios, entre 20 y 39 años, 49 hombres, sin ayuno, con criterios de inclusión definidos para asegurar inexistencia de patología de base, ingesta crónica de fármacos y estado de normovolemia. Tras aplicación de gel se posicionó un transductor linear (10-15 Mhz) sobre el globo ocular para la medición del DVNO; las mediciones fueron realizadas con 0º de inclinación y luego tras cinco minutos en PT. El análisis estadístico fue realizado con STATA 10.0, valor-p < 0,05 para significancia estadística. RESULTADOS: El procedimiento fue tolerado de manera adecuada. Las ventanas ecográficas obtenidas permitieron realizar mediciones en todos los casos con valor de DVNO promedio de 2,3 ± 0,6 mm a 0º y 2,4 ± 0,8 mm a 45º (p = 67), sin diferencia estadística. CONCLUSIÓN: En este grupo de pacientes, jóvenes, sanos, sin patología de base, no sometidos a anestesia y en el contexto "fuera de pabellón", la realización de la ECO ocular permitió la medición del DVNO de manera sencilla, reproducible y sin efectos adversos. La existencia de esta herramienta que estima la PIC de manera indirecta puede ser de gran utilidad anestesiológica.

Humans , Male , Female , Adult , Young Adult , Optic Nerve/diagnostic imaging , Intracranial Pressure/physiology , Reproducibility of Results , Ultrasonography , Myelin Sheath