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Tuberous Sclerosis Complex
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Joana Jesus Ribeiro, Filipe Palavra, Flávio Reis
Cortical tubers are regions of cortical dysplasia that likely result from aberrant neuronal migration during corticogenesis and are observed in ∼90% of TSC patients [2,28]. Dysplastic neurons have disrupted radial orientation in the cortex and abnormal dendritic arborization, showing γ-aminobutyric acid (GABA)-transporter defect and low GABAergic inhibition [1,78]. Tubers are static lesions with variable size and can be multiple in the same individual [77]. They are directly related to the more prevalent neurologic manifestations of TSC, including epilepsy, cognitive impairment, challenging behavioral problems, and autism [13]. These symptoms are highly variable in age at onset and can be detected by fetal MRI or pathological findings as early as 26 weeks of gestation [42]. Cerebral white matter radial migration lines arise from a similar pathologic process as cortical tubers and can be observed in 20%–30% of patients [77]. It is not unusual to find tubers and white matter migrational abnormalities together [2].
Thymus and Neuro-Endocrine-Immune Regulation of Homeostasis
Published in Marek P. Dabrowski, Barbara K. Dabrowska-Bernstein, Immunoregulatory Role of Thymus, 2019
Marek P. Dabrowski, Barbara K. Dabrowska-Bernstein
On the grounds of these data, Hall et al. considered the possibility of a central site of action of thymosin which could result in an increased corticogenesis.154 To test the hypothesis, they first used an in vitro model of isolated adrenal fasciculata cells which normally respond to ACTH with elaboration of glucocorticoids and cAMP. In contrast to the ACTH effects, neither cAMP nor corticosterone release were increased by different regimes of incubation with thymosin fraction 5 or thymosin alpha 1. The thymosins were also unable to potentiate the stimulatory effects of ACTH. In consequence, the authors assumed that the corticogenic effects of thymic hormones could hardly be due to direct stimulation of the adrenal cortex. As the other possible site of thymosin action could be the pituitary cells which produce ACTH, the minced pituitary tissue from adult rats was superfused with thymosin fraction 5 in the next experiment. The results were negative again, as, in contrast to the significant release of ACTH into the medium triggered by corticotropin releasing factor (CRF), the addition of thymosin fraction 5 was without any effect. The pituitary cells were still viable after thymosin treatment as indicated by the preserved ability to release ACTH in response to the subsequent stimulation with CRF. The results, then, were consistently negative for the adrenal cortex and for anterior pituitary as possible sites of thymosin action.
Serum claudin-5, claudin-11, occludin, vinculin, paxillin, and beta-catenin levels in preschool children with autism spectrum disorder
Published in Nordic Journal of Psychiatry, 2023
Ayhan Bilgiç, Hurşit Ferahkaya, Hülya Karagöz, İbrahim Kılınç, Vesile Meltem Energin
Our results showed elevated serum levels of occludin in children with ASD compared to healthy children. We also found a positive relationship between serum occludin levels and the severity of language problems of ASD patients according to the AuBC. A recent study evaluated the potential implications of occludin in ASD and in contradiction with our findings demonstrated lower levels of occludin in patients with ASD than in controls [27]. A recent animal study showed downregulated expression of occludin in the colon of a valproic acid rat model of autism [43]. Alteration in the intestinal paracellular pathway with a breakdown of occludin has been also reported in schizophrenia [26]. Occludin is one of the major tight junction proteins and upregulation or down regulation of its expression causes changes in barrier permeability [44]. Thus, this molecule can have implications for the etiopathogenesis of ASD by affecting permeability. Occludin is also important for early corticogenesis by modulating early neuronal differentiation, progenitor self-renewal, and increased apoptosis [45]. In this context, occludin may have a role in the development of ASD by causing impairment in the developing brain.
Smoking by pregnant mothers and risk of future tobacco use by offspring: a meta-analysis
Published in Journal of Substance Use, 2022
Nicotine dependence is most likely to develop during one of two periods of vulnerability – the prenatal period and adolescence(Mamun, Lawlor et al., 2006) . The adolescent period is critical to cortical development. The frontal cortex develops late in adolescence and helps refine reasoning, setting of priorities and goals, impulse control, and evaluation of long- and short-term rewards (Crews et al., 2007). Therefore, adolescents are particularly vulnerable to addiction. However, prenatal nicotine exposure also influences offspring corticogenesis. Nicotine can transverse the placental barrier, subjecting the fetus to nicotine blood concentrations that exceed those of the mother(Wickstrom, 2007).This phenomenon can result in modifications to the specific neural circuitry of the fetus. Such changes to the function and structure of the brain may lead to clinically characterized deficits, such as sudden infant death syndrome and auditory-cognitive dysfunction (Dwyer et al., 2008). In the fourth gestational week, fetuses develop nicotine acetylcholine receptors, and nicotine exposure thereafter is suggested to produce sensitization and disruption of the pathways mediated by acetylcholine as well as potential birth defects. These changes in children/fetuses or offspring can increase their susceptibility to nicotine dependence. Indeed, uteroexposure to nicotine in rats has been demonstrated to affect the development of the dopaminergic and central serotonergic systems of offspring. Therefore, fetuses exposed to nicotine may experience alterations in the pathways associated with drug rewards.
Neuroimaging and genetic characteristics of malformation of cortical development due to mTOR pathway dysregulation: clues for the epileptogenic lesions and indications for epilepsy surgery
Published in Expert Review of Neurotherapeutics, 2021
Nicola Specchio, Chiara Pepi, Luca De Palma, Marina Trivisano, Federico Vigevano, Paolo Curatolo
TMS is more frequently detected in patients with type IIb than type IIa and is the MRI indicator for type IIb FCD [58–60]. The TMS on MRI overlays the path of migrating neuroblasts, which is consistent with a disruption of early corticogenesis, and is associated with balloon cells and hypomyelination in the WM of the dysplastic lesion [20]. Prognostically, finding the TMS suggests a high probability of a seizure-free outcome post-surgery [61], thought this finding has not always been seen [62]. Further detail from the TMS using T1WI was recently suggested with a group of nine children with FCD type IIb among whom significantly higher number of balloon cells were observed in the group with T1 high signal of the TMS [63]. Confirmation and clinical significance of this latter finding remains to be determined.