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Frontiers in Cell and Developmental... 2022The development of the nervous system is a time-ordered and multi-stepped process that includes neurogenesis and neuronal specification, axonal navigation, and circuits... (Review)
Review
The development of the nervous system is a time-ordered and multi-stepped process that includes neurogenesis and neuronal specification, axonal navigation, and circuits assembly. During axonal navigation, the growth cone, a dynamic structure located at the tip of the axon, senses environmental signals that guide axons towards their final targets. The expression of a specific repertoire of receptors on the cell surface of the growth cone together with the activation of a set of intracellular transducing molecules, outlines the response of each axon to specific guidance cues. This collection of axon guidance molecules is defined by the transcriptome of the cell which, in turn, depends on transcriptional and epigenetic regulators that modify the structure and DNA accessibility to determine what genes will be expressed to elicit specific axonal behaviors. Studies focused on understanding how axons navigate intermediate targets, such as the floor plate of vertebrates or the mammalian optic chiasm, have largely contributed to our knowledge of how neurons wire together during development. In fact, investigations on axon navigation at these midline structures led to the identification of many of the currently known families of proteins that act as guidance cues and their corresponding receptors. Although the transcription factors and the regulatory mechanisms that control the expression of these molecules are not well understood, important advances have been made in recent years in this regard. Here we provide an updated overview on the current knowledge about the transcriptional control of axon guidance and the selection of trajectories at midline structures.
PubMed: 35265625
DOI: 10.3389/fcell.2022.840005 -
Acta Neurobiologiae Experimentalis Sep 2023Studies have shown that vitamin D plays a crucial role in brain development, brain metabolism and neuroprotection. There is little evidence for the neuroprotective...
Studies have shown that vitamin D plays a crucial role in brain development, brain metabolism and neuroprotection. There is little evidence for the neuroprotective effect of 1, 25‑dihydroxyvitamin D3 (1,25‑(OH)2D3) on various brain injury models. The aim of this study was to investigate the neuroprotection effect of 1,25‑(OH)2D3 against hyperoxia‑induced brain injury in premature rats. Sprague‑Dawley rats were exposed to 95% oxygen or room air for 24 h and treated with 1,25‑(OH)2D3 or normal saline for 14 consecutive days. The histopathological changes of optic chiasma tissue were observed by hematoxylin‑eosin staining. Immunohistochemistry, qRT‑PCR, and western blot were performed to detect the expression of integrin‑β1 and yes‑associated protein (YAP) in the organization of the optic chiasm. Histopathological sections of optic chiasma showed visible optic nerve swelling, expanded nerve fiber space, uneven staining, obvious oligodendrocyte proliferation and disordered cell arrangement accompanied by inflammatory cell infiltration and exudation after 7 days and 14 days of hyperoxia exposure. The hyperoxia group treated with 1,25‑(OH)2D3 were showed improvement of brain injury with reduced inflammatory exudation, uniform nerve fiber staining and less obvious oligodendrocyte proliferation. Immunohistochemical staining, qRT‑PCR and western blot indicated that 1,25‑(OH)2D3 treatment upregulated the expression of integrin‑β1 and YAP in the hyperoxia group on day 7. However, the expression of YAP was significantly increased compared with control group and treatment with 1,25‑(OH)2D3 reduced the expression of YAP in the hyperoxic group on day 14. 1,25‑(OH)2D3 may regulate the expression of integrin‑β1 and YAP to alleviate hyperoxia‑induced brain injury in premature rats.
Topics: Rats; Animals; Calcitriol; Neuroprotective Agents; Hyperoxia; Rats, Sprague-Dawley; Vitamin D; Brain Injuries; Integrins
PubMed: 37874188
DOI: 10.55782/ane-2023-2435 -
Neural Regeneration Research Mar 2022Retinal ganglion cell (RGC) axons provide the only link between the light sensitive and photon transducing neural retina and visual centers of the brain. RGC axon...
Retinal ganglion cell (RGC) axons provide the only link between the light sensitive and photon transducing neural retina and visual centers of the brain. RGC axon degeneration occurs in a number of blinding diseases and the ability to stimulate axon regeneration from surviving ganglion cells could provide the anatomic substrate for restoration of vision. OTX2 is a homeoprotein transcription factor expressed in the retina and previous studies showed that, in response to stress, exogenous OTX2 increases the in vitro and in vivo survival of RGCs. Here we examined and quantified the effects of OTX2 on adult RGC axon regeneration in vitro and in vivo. The results show that exogenous OTX2 stimulates the regrowth of axons from RGCs in cultures of dissociated adult retinal cells and from explants of adult retinal tissue and that RGCs respond directly to OTX2 as regrowth is observed in cultures of purified adult rat RGCs. Importantly, after nerve crush in vivo, we observed a positive effect of OTX2 on the number of regenerating axons up to the optic chiasm within 14 days post crush and a very modest level of acuity absent in control mice. The effect of OTX2 on RGC survival and regeneration is of potential interest for degenerative diseases affecting this cell type. All animal procedures were approved by the local "Comié d'éιthique en expérimentation animale n°59" and authorization n° 00702.01 delivered March 28, 2014 by the French "Ministére de l'enseignement supérieur et de la recherche".
PubMed: 34380911
DOI: 10.4103/1673-5374.320989 -
Journal of the Formosan Medical... Jan 2022
Topics: Hemorrhage; Humans; Magnetic Resonance Imaging; Optic Chiasm
PubMed: 34602317
DOI: 10.1016/j.jfma.2021.09.012 -
Ceska a Slovenska Oftalmologie :... 2023Prolactinoma is a pituitary adenoma that secretes prolactin. Approximately 40% of all pituitary adenomas are prolactinomas. According to size, they are divided into...
AIM
Prolactinoma is a pituitary adenoma that secretes prolactin. Approximately 40% of all pituitary adenomas are prolactinomas. According to size, they are divided into micro, macro and giant prolactinomas. In women, prolactinomas cause irregularities of the menstrual cycle such as amenorrhea, galactorrhea, weight gain, in both sexes they cause sterility, hypogonadism, decreased libido and depression. In macroadenomas, symptoms due to the compression of the surrounding structures are also manifested, such as headache, vomiting, lower chiasmatic syndrome and ophthalmoplegia. Loss of the visual field due to compression of the optic chiasm is caused by a tumor larger than 10-15 mm with suprasellar spreading, which breaks through the diaphragma sellae. Giant prolactinomas are larger than 40 mm and make up 1-5% of all prolactinomas.
CASE REPORT
In this article I present the case of a 38-year-old woman from Ukraine with advanced chiasmatic syndrome caused by a giant prolactinoma. The tumor is infiltrating the left cavernous sinus, causing left-sided amaurosis and right-sided temporal hemianopsia.
CONCLUSION
Inferior chiasmatic syndrome is characterized by bitemporal hemianopsia, a deterioration of visual acuity, bilateral bow-tie descendent atrophy of the optic nerve disc, and hemianopic rigidity of the pupils. Macroprolactinomas occur more frequently in men than in women. The diagnosis is often delayed, probably because the symptoms of hyperprolactinemia are less obvious in men, while women tend to present earlier due to menstrual cycle irregularities. Prolactinomas usually have a good prognosis. Effective medical treatment with dopamine agonists is available. Knowledge of the prolactinoma symptoms could help the diagnosis of compressive lesions of the optic chiasm.
Topics: Male; Pregnancy; Female; Humans; Adult; Prolactinoma; Pituitary Neoplasms; Hyperprolactinemia; Dopamine Agonists; Prolactin
PubMed: 37344216
DOI: 10.31348/2023/20 -
Brain Tumor Research and Treatment Apr 2022Optic pathway glioma (OPG) is a rare tumor located in optic nerve, optic tract, or optic chiasm. Treatment options for OPG include surgery, radiation therapy (RT), and... (Review)
Review
Optic pathway glioma (OPG) is a rare tumor located in optic nerve, optic tract, or optic chiasm. Treatment options for OPG include surgery, radiation therapy (RT), and chemotherapy. Although RT may provide favorable long-term outcomes in manner of either adjuvant or salvage aim, chemotherapy-first approach is increasingly performed due to possible late effects of RT. Proton beam RT may allow normal tissue sparing of radiation exposure compared to conventional X-ray treatment. Therefore, proton beam RT is expected to reduce complications from RT. This review discusses the recent updates on oncologic outcomes of OPG, late toxicities following RT, and compares the outcomes between X-ray treatment and proton beam RT.
PubMed: 35545828
DOI: 10.14791/btrt.2022.0003 -
Arquivos de Neuro-psiquiatria Jun 2023There is clinical and radiological overlap among demyelinating diseases. However, their pathophysiological mechanisms are different and carry distinct prognoses and...
BACKGROUND
There is clinical and radiological overlap among demyelinating diseases. However, their pathophysiological mechanisms are different and carry distinct prognoses and treatment demands.
OBJECTIVE
To investigate magnetic resonance imaging (MRI) features of patients with myelin-oligodendrocyte glycoprotein associated disease (MOGAD), antibody against aquaporin-4(AQP-4)-immunoglobulin G-positive neuromyelitis optica spectrum disorder (AQP4-IgG NMOSD), and double-seronegative patients.
METHODS
A cross-sectional retrospective study was performed to analyze the topography and morphology of central nervous system (CNS) lesions. Two neuroradiologists consensually analyzed the brain, orbit, and spinal cord images.
RESULTS
In total, 68 patients were enrolled in the study (25 with AQP4-IgG-positive NMOSD, 28 with MOGAD, and 15 double-seronegative patients). There were differences in clinical presentation among the groups. The MOGAD group had less brain involvement (39.2%) than the NMOSD group ( = 0.002), mostly in the subcortical/juxtacortical, the midbrain, the middle cerebellar peduncle, and the cerebellum. Double-seronegative patients had more brain involvement (80%) with larger and tumefactive lesion morphology. In addition, double-seronegative patients showed the longest optic neuritis ( = 0.006), which was more prevalent in the intracranial optic nerve compartment. AQP4-IgG-positive NMOSD optic neuritis had a predominant optic-chiasm location, and brain lesions mainly affected hypothalamic regions and the postrema area (MOGAD versus AQP4-IgG-positive NMOSD, = 0 .013). Furthermore, this group had more spinal cord lesions (78.3%), and bright spotty lesions were a paramount finding to differentiate it from MOGAD ( = 0.003).
CONCLUSION
The pooled analysis of lesion topography, morphology, and signal intensity provides critical information to help clinicians form a timely differential diagnosis.
Topics: Myelin-Oligodendrocyte Glycoprotein; Cross-Sectional Studies; Retrospective Studies; Magnetic Resonance Imaging; Immunoglobulin G
PubMed: 37379865
DOI: 10.1055/s-0043-1768669 -
NeuroImage. Clinical 2023The anterior optic pathway (AOP) is a system of three structures (optic nerves, optic chiasma, and optic tracts) that convey visual stimuli from the retina to the... (Review)
Review
The anterior optic pathway (AOP) is a system of three structures (optic nerves, optic chiasma, and optic tracts) that convey visual stimuli from the retina to the lateral geniculate nuclei. A successful reconstruction of the AOP using tractography could be helpful in several clinical scenarios, from presurgical planning and neuronavigation of sellar and parasellar surgery to monitoring the stage of fiber degeneration both in acute (e.g., traumatic optic neuropathy) or chronic conditions that affect AOP structures (e.g., amblyopia, glaucoma, demyelinating disorders or genetic optic nerve atrophies). However, its peculiar anatomy and course, as well as its surroundings, pose a serious challenge to obtaining successful tractographic reconstructions. Several AOP tractography strategies have been adopted but no standard procedure has been agreed upon. We performed a systematic review of the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 guidelines in order to find the combinations of acquisition and reconstruction parameters that have been performed previously and have provided the highest rate of successful reconstruction of the AOP, in order to promote their routine implementation in clinical practice. For this purpose, we reviewed data regarding how the process of anatomical validation of the tractographies was performed. The Cochrane Handbook for Systematic Reviews of Interventions was used to assess the risk of bias and thus the study quality We identified thirty-nine studies that met our inclusion criteria, and only five were considered at low risk of bias and achieved over 80% of successful reconstructions. We found a high degree of heterogeneity in the acquisition and analysis parameters used to perform AOP tractography and different combinations of them can achieve satisfactory levels of anterior optic tractographic reconstruction both in real-life research and clinical scenarios. One thousand s/mm was the most frequently used b value, while both deterministic and probabilistic tractography algorithms performed morphological reconstruction of the tract satisfactorily, although probabilistic algorithms estimated a more realistic percentage of crossing fibers (45.6%) in healthy subjects. A wide heterogeneity was also found regarding the method used to assess the anatomical fidelity of the AOP reconstructions. Three main strategies can be found: direct visual direct visual assessment of the tractography superimposed to a conventional MR image, surgical evaluation, and computational methods. Because the latter is less dependent on a priori knowledge of the anatomy by the operator, computational methods of validation of the anatomy should be considered whenever possible.
Topics: Humans; Diffusion Magnetic Resonance Imaging; Magnetic Resonance Imaging; Diffusion Tensor Imaging; Retina; Amblyopia
PubMed: 37651845
DOI: 10.1016/j.nicl.2023.103494