[Superior canal dehiscence - Case report].

UNLABELLED: Superior canal dehiscence is a rare syndrome. The symptoms consist of hearing loss, dizziness and autophonia. The patient can be cured with surgery. A 28 year old woman went to several doctors for several months due to diminished hearing, dizziness and autophonia. The symptoms got worse. A work-up led to the diagnosis of superior canal dehiscence in the left ear. She underwent surgery and her symptoms improved. A latency in diagnosis is expected as the syndrome is rare. It's important to think of superior canal dehiscence when patients complain of these symptoms. KEY WORDS: superior canal dehiscence, autophonia, dizziness, hearing deficit. Correspondence: Bryndis Baldvinsdottir, bryndisbaldvins@gmail.com.

Genetic correction of human induced pluripotent stem cells from patients with spinal muscular atrophy.

Spinal muscular atrophy (SMA) is among the most common genetic neurological diseases that cause infant mortality. Induced pluripotent stem cells (iPSCs) generated from skin fibroblasts from SMA patients and genetically corrected have been proposed to be useful for autologous cell therapy. We generated iPSCs from SMA patients (SMA-iPSCs) using nonviral, nonintegrating episomal vectors and used a targeted gene correction approach based on single-stranded oligonucleotides to convert the survival motor neuron 2 (SMN2) gene into an SMN1-like gene. Corrected iPSC lines contained no exogenous sequences. Motor neurons formed by differentiation of uncorrected SMA-iPSCs reproduced disease-specific features. These features were ameliorated in motor neurons derived from genetically corrected SMA-iPSCs. The different gene splicing profile in SMA-iPSC motor neurons was rescued after genetic correction. The transplantation of corrected motor neurons derived from SMA-iPSCs into an SMA mouse model extended the life span of the animals and improved the disease phenotype. These results suggest that generating genetically corrected SMA-iPSCs and differentiating them into motor neurons may provide a source of motor neurons for therapeutic transplantation for SMA.

Direct reprogramming of human astrocytes into neural stem cells and neurons.

Generating neural stem cells and neurons from reprogrammed human astrocytes is a potential strategy for neurological repair. Here we show dedifferentiation of human cortical astrocytes into the neural stem/progenitor phenotype to obtain progenitor and mature cells with a neural fate. Ectopic expression of the reprogramming factors OCT4, SOX2, or NANOG into astrocytes in specific cytokine/culture conditions activated the neural stem gene program and induced generation of cells expressing neural stem/precursor markers. Pure CD44+ mature astrocytes also exhibited this lineage commitment change and did not require passing through a pluripotent state. These astrocyte-derived neural stem cells gave rise to neurons, astrocytes, and oligodendrocytes and showed in vivo engraftment properties. ASCL1 expression further promoted neuronal phenotype acquisition in vitro and in vivo. Methylation analysis showed that epigenetic modifications underlie this process. The restoration of multipotency from human astrocytes has potential in cellular reprogramming of endogenous central nervous system cells in neurological disorders.

Comparative long-term adverse effects elicited by invasive group B and C meningococcal infections.

BACKGROUND: Given the identity between Neisseria meningitidis serogroup B (MenB) capsular polysaccharide (polysialic acid; PSA) and PSA found on neural cell adhesion molecules, it has been proposed that infection with MenB or vaccination with PSA may be associated with subsequent autoimmune or neurological disease. METHODS: We conducted 2 studies. The first was a retrospective nationwide study of invasive meningococcal disease (IMD) in Iceland (with 541 subjects) during the period 1975-2004, and we cross referenced this cohort with databases with respect to subsequent diagnosis of autoimmune disorders. A follow-up study involving 120 survivors of IMD was performed. The study included 70 patients with a history of MenB and 50 patients with N. meningitidis serogroup C (MenC) infection, who served as control subjects. Participants answered standardized questionnaires (Beck's Depression Inventory [BDI] II, Depression Anxiety Stress Scales [DASS], and Patient Health Questionnaire [PHQ]), and serum levels of immunoglobulin (Ig) G against MenB and MenC capsular polysaccharides were measured. RESULTS: The nationwide cohort had 9166 patient-years of follow up. No evidence of increased autoimmunity was found to be associated with MenB, compared with MenC. In the follow-up study, patients were evaluated 16.6 years after the infection, representing 2022 patient-years of observation. Comparable rates of most complications were recorded, but MenC infections were associated with arthritis (P = .008) and migraine headaches (P = .01) more frequently than were MenB infections. No difference was observed with respect to scores on BDI-II, DASS, or PHQ. IgG anti-MenB and anti-MenC capsular polysaccharide levels were not related to patient complaints. CONCLUSIONS: This study does not support the hypothesis that MenB infection may predispose to autoimmunity. MenC infections are associated with a higher prevalence of arthritis and migraine headaches. No evidence of antibody-associated pathology was detected at long-term follow-up.

Beta-lactam antibiotic offers neuroprotection in a spinal muscular atrophy model by multiple mechanisms.

Spinal muscular atrophy (SMA) is a devastating genetic motoneuron disease leading to infant death. No effective therapy is currently available. It has been suggested that ß-lactam antibiotics such as ceftriaxone may offer neuroprotection in motoneuron diseases. Here, we investigate the therapeutic effect of ceftriaxone in a murine model of SMA. Treated animals present a modest, but significant ameliorated neuromuscular phenotype and increased survival, which correlate with protection of neuromuscular units. Whole gene expression profiling in treated mice demonstrates modifications in several genes including those involved in RNA metabolism toward wild-type. The neuroprotective effect seems to be mediated by multiple mechanisms that encompass the increase of the glutamate transporter Glt1, the transcription factor Nrf2, as well as SMN protein. This study provides the first evidence of a potential positive effect of this class of molecules in SMA. Further investigation of analogs with increased and more specific therapeutic effects warrants the development of useful therapies for SMA.

Systemic transplantation of c-kit+ cells exerts a therapeutic effect in a model of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal, neurodegenerative disease characterized by the loss of motor neurons. Motor neuron degeneration is probably both a cell autonomous and a non-autonomous event. Therefore, manipulating the diseased microenvironment via non-neural cell replacement could be a therapeutic strategy. We investigated a cell therapy approach using intravascular injection to transplant a specific population of c-kit(+) stem/progenitor cells from bone marrow into the SOD1G93A mouse model of ALS. Transplanted cells engrafted within the host spinal cord. Cell transplantation significantly prolonged disease duration and lifespan in superoxide dismutase 1 mice, promoted the survival of motor neurons and improved neuromuscular function. Neuroprotection was mediated by multiple effects, in particular by the expression of primary astrocyte glutamate transporter GLT1 and by the non-mutant genome. These findings suggest that this type of somatic cell transplantation strategy merits further investigation as a possible effective therapy for ALS and other neurodegenerative diseases.

Embryonic stem cell-derived neural stem cells improve spinal muscular atrophy phenotype in mice.

Spinal muscular atrophy, characterized by selective loss of lower motor neurons, is an incurable genetic neurological disease leading to infant mortality. We previously showed that primary neural stem cells derived from spinal cord can ameliorate the spinal muscular atrophy phenotype in mice, but this primary source has limited translational value. Here, we illustrate that pluripotent stem cells from embryonic stem cells show the same potential therapeutic effects as those derived from spinal cord and offer great promise as an unlimited source of neural stem cells for transplantation. We found that embryonic stem cell-derived neural stem cells can differentiate into motor neurons in vitro and in vivo. In addition, following their intrathecal transplantation into spinal muscular atrophy mice, the neural stem cells, like those derived from spinal cord, survived and migrated to appropriate areas, ameliorated behavioural endpoints and lifespan, and exhibited neuroprotective capability. Neural stem cells obtained using a drug-selectable embryonic stem cell line yielded the greatest improvements. As with cells originating from primary tissue, the embryonic stem cell-derived neural stem cells integrated appropriately into the parenchyma, expressing neuron- and motor neuron-specific markers. Our results suggest translational potential for the use of pluripotent cells in neural stem cell-mediated therapies and highlight potential safety improvements and benefits of drug selection for neuroepithelial cells.

Motoneuron transplantation rescues the phenotype of SMARD1 (spinal muscular atrophy with respiratory distress type 1).

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a fatal form of infantile motoneuron disease. There is currently no effective treatment, although motor neuron replacement is a possible therapeutic strategy. We transplanted purified motor neurons into the spinal cord of nmd mice, an animal model of SMARD1. We also administered pharmacological treatment targeting the induction of axonal growth toward skeletal muscle target. At the end stage of the disease, donor-derived motor neurons were detected in the nmd anterior horns, extended axons into the ventral roots, and formed new neuromuscular junctions. These data correlated with improved neuromuscular function and increased life spans. The neuroprotective effect was associated with a reduction in proinflammatory molecules in treated spinal cords. This is the first report that functional restoration of motor units with transplanted motoneurons is feasible in an animal model of a human motoneuron disease, opening up new possibilities for therapeutic intervention.

Is erythropoietin gene a modifier factor in amyotrophic lateral sclerosis?

To investigate the role of erythropoietin (EPO) as genetic determinant in the susceptibility to sporadic amyotrophic lateral sclerosis (SALS). We sequenced a 259-bp region spanning the 3'hypoxia-responsive element of the EPO gene in 222 Italian SALS patients and 204 healthy subjects, matched for age and ethnic origin. No potentially causative variation was detected in SALS subjects; in addition, two polymorphic variants (namely C3434T and G3544T) showed the same genotype and haplotype frequencies in patients and controls. Conversely, a weak but significant association between G3544T and age of disease onset was observed (p=0.04). Overall, our data argue against the hypothesis of EPO as a genetic risk factor for motor neuron dysfunction, at least in Italian population. However, further studies on larger cohort of patients are needed to confirm the evidence of EPO gene as modifier factor.

Neural stem cell transplantation can ameliorate the phenotype of a mouse model of spinal muscular atrophy.

Spinal muscular atrophy (SMA), a motor neuron disease (MND) and one of the most common genetic causes of infant mortality, currently has no cure. Patients with SMA exhibit muscle weakness and hypotonia. Stem cell transplantation is a potential therapeutic strategy for SMA and other MNDs. In this study, we isolated spinal cord neural stem cells (NSCs) from mice expressing green fluorescent protein only in motor neurons and assessed their therapeutic effects on the phenotype of SMA mice. Intrathecally grafted NSCs migrated into the parenchyma and generated a small proportion of motor neurons. Treated SMA mice exhibited improved neuromuscular function, increased life span, and improved motor unit pathology. Global gene expression analysis of laser-capture-microdissected motor neurons from treated mice showed that the major effect of NSC transplantation was modification of the SMA phenotype toward the wild-type pattern, including changes in RNA metabolism proteins, cell cycle proteins, and actin-binding proteins. NSC transplantation positively affected the SMA disease phenotype, indicating that transplantation of NSCs may be a possible treatment for SMA.

Absence of angiogenic genes modification in Italian ALS patients.

To investigate the role of vascular endothelial growth factor (VEGF) and angiogenin (ANG) as genetic determinants in the susceptibility to sporadic ALS in Italian patients. VEGF genotype and haplotype analysis revealed no association between any variants and the risk of ALS. Regarding ANG gene, no mutation was detected and the rs11701 polymorphism, previously described as associated with ALS, was not differently distributed between patients and controls. Overall, our data argue against the hypothesis of both genes as risk factors for motoneuron neurodegeneration, at least in an Italian population.

Fas small interfering RNA reduces motoneuron death in amyotrophic lateral sclerosis mice.

OBJECTIVE: Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease characterized by selective motoneuron death. Understanding of the molecular mechanisms that trigger and regulate motoneuron degeneration could be relevant to ALS and other motoneuron disorders. This study investigates the role of Fas-linked motoneuron death in the pathogenesis of ALS. METHODS: We performed in vitro and in vivo small interfering RNA-mediated interference, by silencing the Fas receptor on motoneurons that carry the superoxide dismutase-1 (SOD1)-G93A mutation. RESULTS: We observed a significant reduction in Fas expression at messenger RNA (p < 0.001) and protein levels. Treated motoneurons demonstrated an increase in survival and a reduction in cytochrome c release from mitochondria. In vivo, continuous intrathecal administration of Fas small interfering RNA by an osmotic minipump improved motor function and survival in SOD1-G93A mice (mean increase, 18 days; p < 0.0001). Treated mice showed a significant reduction in Fas and Fas mediators p38 mitogen-activated protein kinase, neuronal nitric oxide synthase, and caspase-8. INTERPRETATION: Fas silencing interferes with motoneuron-specific downstream death pathways and results in increased motoneuron survival and amelioration of the SOD1-G93A phenotype, suggesting new possible strategies for molecular therapy of ALS.

Isolation and characterization of murine neural stem/progenitor cells based on Prominin-1 expression.

The identification of strategies for the isolation of neural stem cells (NSCs) has important implications for the understanding of their biology and the development of therapeutic applications. It has been previously described that human neural stem and progenitor cells (NSPCs) can be isolated from the central nervous system (CNS) using antibodies to prominin (CD133) and fluorescence-activated cell sorting (FACS). Although this antigen displayed an identical membrane topology in several human and murine tissues there was uncertainty as to the relationship between human and mouse prominin because of the low level of amino acid identity. Here we show that prominin expression can be used to identify and isolate also murine NSPCs from the developing or adult brain. Prominin is co-expressed with known neural stem markers like SOX 1-2, Musashi and Nestin. Moreover, neurosphere-forming cells with multipotency and self-renewal capacity reside within the prominin-positive fraction. Transplantation experiments show that CD133-positive cells give rise to neurons and glial cells in vivo, and that many neurons display appropriate phenotypic characteristics of the recipient tissues. The demonstration that CD133 is a stem cell antigen for murine NSPCs as it is for human NSPCs is useful for the investigation of mammal neurogenesis and development of preclinical tests of NSPCs transplantation in mouse analogues of human diseases.

Neural stem cells LewisX+ CXCR4+ modify disease progression in an amyotrophic lateral sclerosis model.

Amyotrophic lateral sclerosis (ALS) is a fatal neurological disease characterized by the degeneration of the motor neurons. We tested whether treatment of superoxide dismutase (SOD1)-G93A transgenic mouse, a model of ALS, with a neural stem cell subpopulation double positive for Lewis X and the chemokine receptor CXCR4 (LeX+CXCR4+) can modify the disease's progression. In vitro, after exposure to morphogenetic stimuli, LeX+CXCR4+ cells generate cholinergic motor neuron-like cells upon differentiation. LeX+CXCR4+ cells deriving from mice expressing Green Fluorescent Protein in all tissues or only in motor neurons, after a period of priming in vitro, were grafted into spinal cord of SOD1-G93A mice. Transplanted transgenic mice exhibited a delayed disease onset and progression, and survived significantly longer than non-treated animals by 23 days. Examination of the spinal cord revealed integration of donor-derived cells that differentiated mostly in neurons and in a lower proportion in motor neuron-like cells. Quantification of motor neurons of the spinal cord suggests a significant neuroprotection by LeX+CXCR4+ cells. Both VEGF- and IGF1-dependent pathways were significantly modulated in transplanted animals compared to controls, suggesting a role of these neurotrophins in MN protection. Our results support the therapeutic potential of neural stem cell fractions through both neurogenesis and growth factors release in motor neuron disorders.

XHas2 activity is required during somitogenesis and precursor cell migration in Xenopus development.

In vertebrates, hyaluronan biosynthesis is regulated by three transmembrane catalytic enzymes denoted Has1, Has2 and Has3. We have previously cloned the Xenopus orthologues of the corresponding genes and defined their spatiotemporal distribution during development. During mammalian embryogenesis, Has2 activity is known to be crucial, as its abrogation in mice leads to early embryonic lethality. Here, we show that, in Xenopus, morpholino-mediated loss-of-function of XHas2 alters somitogenesis by causing a disruption of the metameric somitic pattern and leads to a defective myogenesis. In the absence of XHas2, early myoblasts underwent apoptosis, failing to complete their muscle differentiation programme. XHas2 activity is also required for migration of hypaxial muscle cells and trunk neural crest cells (NCC). To approach the mechanism whereby loss of HA, following XHas2 knockdown, could influence somitogenesis and precursor cell migration, we cloned the orthologue of the primary HA signalling receptor CD44 and addressed its function through an analogous knockdown approach. Loss of XCD44 did not disturb somitogenesis, but strongly impaired hypaxial muscle precursor cell migration and the subsequent formation of the ventral body wall musculature. In contrast to XHas2, loss of function of XCD44 did not seem to be essential for trunk NCC migration, suggesting that the HA dependence of NCC movement was rather associated with an altered macromolecular composition of the ECM structuring the cells' migratory pathways. The presented results, extend our knowledge on Has2 function and, for the first time, demonstrate a developmental role for CD44 in vertebrates. On the whole, these data underlie and confirm the emerging importance of cell-ECM interactions and modulation during embryonic development.

5-HT2B-mediated serotonin signaling is required for eye morphogenesis in Xenopus.

In this paper, we show that serotonin, via 5-HT2B receptor, is involved in Xenopus retinal histogenesis and eye morphogenesis by supporting cell proliferation and survival. To analyze the 5-HT2B function in retinal development, we performed a loss-of-function study using both a pharmacological and a morpholino antisense oligonucleotide approach. Gain-of-function experiments were made by microinjecting 5-HT2B mRNA. Misregulation of the 5-HT2B receptor activity causes alterations in the proliferation rate and survival of retinal precursors, resulting in abnormal retinal morphology, where lamination is severely compromised. Clones derived from lipofected retinoblasts that overexpress 5-HT2B show an increase in the relative percentage of ganglion cells, possibly due to protection from apoptosis. This effect is reversed in clones lipofected with a 5-HT2B-specific morpholino. We hypothesize that the survival of the correct number of ganglion cells is controlled by 5-HT/5-HT2B signaling. Serotonin, acting as a neurotrophic factor, may contribute by refining retinal connectivity and cytoarchitecture.

Regulated gene expression of hyaluronan synthases during Xenopus laevis development.

Here reported is the developmental gene expression pattern of the three known vertebrate hyaluronan synthases (XHas1, XHas2 and XHas3) and a comparative analysis of their mRNAs spatio-temporal distribution during Xenopus laevis development. We found that while XHas2 shows a steady-state expression from gastrula to late tailbud stage, XHas1 is mainly present in the early phases of development while XHas3 is predominantly transcribed in tailbud embryos. XHas1, XHas2 and XHas3 show distinct tissue expression patterns. In particular, XHas1 is localized in ectodermal derivatives and in cranial neural crest cells, whereas XHas2 is mainly found in mesoderm-derived structures and in trunk neural crest cells. Moreover, the expression pattern of XHas2 overlaps that of MyoD in cells committed to a muscle fate. Unlike the other hyaluronan synthases, XHas3 mRNA distribution is very restricted. In particular, XHas3 is expressed in the otic vesicles and closely follows the inner ear development. In conclusion, XHas1, XHas2 and XHas3 mRNAs have distinct and never overlapping spatial expression domains, which would suggest that these three enzymes may play different roles during embryogenesis.

Expression of 5-HT2B and 5-HT2C receptor genes is associated with proliferative regions of Xenopus developing brain and eye.

Here we clone the Xenopus 5-HT2B receptor cDNA and describe its spatio-temporal mRNA expression within the developing larval brain and visual system. Expression of the 5-HT2B transcripts is compared to that of 5-HT2C as well as proliferation and neurogenic markers. In developing brain and retina, 5-HT2B and 2C mRNAs are mainly expressed in proliferative regions. We suggest that these receptors may play a role in the larval secondary neurogenesis by mediating mitogenic effects of serotonin.