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1.
Frataxin deficiency in Friedreich’s ataxia (FRDA) causes cardiac, endocrine, and nervous system manifestations. Frataxin is a mitochondrial protein, and adequate amounts are essential for cellular iron homeostasis. The main histological lesion in the brain of FRDA patients is neuronal atrophy and a peculiar proliferation of synaptic terminals in the dentate nucleus termed grumose degeneration. This cerebellar nucleus may be especially susceptible to FRDA because it contains abundant iron. We examined total iron and selected iron-responsive proteins in the dentate nucleus of nine patients with FRDA and nine normal controls by biochemical and microscopic techniques. Total iron (1.53 ± 0.53 μmol/g wet weight) and ferritin (206.9 ± 46.6 μg/g wet weight) in FRDA did not significantly differ from normal controls (iron: 1.78 ± 0.88 μmol/g; ferritin: 210.9 ± 9.0 μg/g) but Western blots exhibited a shift to light ferritin subunits. Immunocytochemistry of the dentate nucleus revealed loss of juxtaneuronal ferritin-containing oligodendroglia and prominent ferritin immunoreactivity in microglia and astrocytes. Mitochondrial ferritin was not detectable by immunocytochemistry. Stains for the divalent metal transporter 1 confirmed neuronal loss while endothelial cells reacting with antibodies to transferrin receptor 1 protein showed crowding of blood vessels due to collapse of the normal neuropil. Regions of grumose degeneration were strongly reactive for ferroportin. Purkinje cell bodies, their dendrites and axons, were also ferroportin-positive, and it is likely that grumose degeneration is the morphological manifestation of mitochondrial iron dysmetabolism in the terminals of corticonuclear fibers. Neuronal loss in the dentate nucleus is the likely result of trans-synaptic degeneration.  相似文献   
2.
OBJECTIVE: Increasing evidence suggests a significant comorbidity between attention-deficit/hyperactivity disorder (ADHD) and restless legs syndrome (RLS). Iron deficiency may underlie common pathophysiological mechanisms in subjects with ADHD plus RLS (ADHD+RLS). To date, the impact of iron deficiency, RLS and familial history of RLS on ADHD severity has been scarcely examined in children. These issues are addressed in the present study. METHODS: Serum ferritin levels, familial history of RLS (diagnosed using National Institutes of Health (NIH) criteria) and previous iron supplementation in infancy were assessed in 12 ADHD+RLS children, 10 ADHD children and 10 controls. RLS was diagnosed using NIH-specific pediatric criteria, and ADHD severity was assessed using the Conners' Parent Rating scale. RESULTS: ADHD symptom severity was higher, although not significantly, in children with ADHD+RLS compared to ADHD. The mean serum ferritin levels were significantly lower in children with ADHD than in the control group (p<0.0005). There was a trend for lower ferritin levels in ADHD+RLS subjects versus ADHD. Both a positive family history of RLS and previous iron supplementation in infancy were associated with more severe ADHD scores. CONCLUSIONS: Children with ADHD and a positive family history of RLS appear to represent a subgroup particularly at risk for severe ADHD symptoms. Iron deficiency may contribute to the severity of symptoms. We suggest that clinicians consider assessing children with ADHD for RLS, a family history of RLS, and iron deficiency.  相似文献   
3.
Hereditary ferritinopathies are dominant inherited movement disorders associated with extensive alterations of the l-ferritin C-terminus peptide caused by nucleotide insertions in l-ferritin gene (FTL). We describe the characterization of the most common variant, produced by the 460InsA mutations and here named Ln1. The recombinant Ln1 assembled into 24-mer ferritin shells with low efficiency, however, it was able to form heteropolymers that showed a reduced capacity to incorporate iron in vitro. The Ln1 expressed in HeLa cells formed hybrid ferritins, with the endogenous H and L chains, and caused an iron excess phenotype. Ferritin inactivation and faster degradation in Ln1 transfectants concurred in increasing iron availability, which was probably responsible for the higher sensitivity to H(2)O(2) toxicity and higher level of oxidized proteins. The findings suggest that the pathogenic effects of Ln1 expression are more likely due to deregulation of cellular iron homeostasis rather than to protein conformational problems.  相似文献   
4.
Neuroferritinopathy (MIM 606159, also labeled hereditary ferritinopathy and neurodegeneration with brain iron accumulation type 2, NBIA2) is an adult-onset progressive movement disorder caused by mutations in the ferritin light chain gene (FTL1). Four pathogenic mutations in FTL1 have been described to date; 460insA was our original founder mutation in Cumbria, North West England, where it arose before 1800. The same mutation appears to have arisen separately in France. The resulting altered reading frame extends the peptide, disrupting the ferritin dodecahedron structure and causing accumulation of ferritin and iron, primarily in central neurons. A wide range of neurologic symptoms may occur; 50% present with chorea, 43% with limb dystonia, and 7% with Parkinsonian features. The disorder provides a direct link between disordered iron storage and a neurodegenerative disease, opening new avenues for treatment by altering brain iron stores in addition to symptomatic treatments such as local Botulinum toxin and oral anti oxidants.  相似文献   
5.
This study mapped the distribution of ferroportin in the developing rat brain using Wistar rats aged postnatal (P) days P7, P21, and P70 (adult). Ferroportin immunoreactivity was observed in neurons throughout the CNS regardless of the age of the animals studied. The neuronal labeling was detected in both perikarya, and axons and dendrites. The labeling intensity within the neurons varied among the different ages of the rats with an overall higher ferroportin immunoreactivity seen at P21, particularly in axons and white matter tracts. The neuronal labeling was high in the neocortex, striatum, hippocampus, brain stem nuclei, deep cerebellar nuclei, catecholaminergic neurons, and reticular nuclei, and particularly high in neurons of the mesencephalic trigeminal nucleus and medial habenular nucleus. In axonal tracts, ferroportin immunoreactivity was high in fibers of the internal capsule, fimbria, mamillothalamic tract and the habenulo-interpedunculo pathway. Slight ferroportin immunoreactivity was observed in oligodendrocytes and differentiating macrophages that invade the postnatal brain. The finding of a pronounced content of ferroportin in axons of the developing brain are in keeping with the idea of elevated axonal transport and export of iron possibly because of higher metabolic needs.  相似文献   
6.
OBJECTIVE: To determine the minimum prevalence of spinocerebellar ataxia type 17 (SCA17) in the north east of England. PATIENTS AND METHODS: A defined region containing 2,516,500 individuals with 192 families with undiagnosed ataxia, 90 patients with a Huntington's disease-like phenotype and 292 controls. The number of (CAG/CAA)(n) repeats in the SCA17/TBP gene was determined by fluorescent PCR and sequenced in affected individuals. RESULTS: The mean repeat size for 584 control alleles was 34 (S.D.=3.58), ranging from 25 to 40. Two index cases had larger alleles with repeat lengths greater than the control range. Affected family members presented in adult life with ataxia followed by extrapyramidal features and cognitive impairment. In one family 44 repeats were associated with a younger age of onset than has been previously described. CONCLUSIONS: The minimum prevalence of SCA17 in the north east of England was 0.16/100,000 (upper 95% confidence interval 0.31/100,000).  相似文献   
7.
Aceruloplasminemia (ACP) is an inherited disorder of iron metabolism caused by the lack of ceruloplasmin activity; the neuropathological hallmarks are excessive iron deposition, neuronal loss, bizarrely deformed astrocytes, and numerous 'grumose or foamy spheroid bodies (GFSBs)'. We histopathologically examined two autopsied ACP brains, and observed for the first time that GFSBs form in clusters at the ends of perivascular astrocytic foot processes. Both the deformed astrocytes and the GFSBs contained ferric iron and were intensely immunolabelled with antibodies against the antioxidant proteins ferritin and manganese superoxide dismutase (Mn SOD). Ceruloplasmin is largely produced by perivascular astrocytes in the central nervous system and exhibits a ferroxidase activity that inhibits iron-associated lipid peroxidation and hydroxyl radical formation; therefore, the lack of ceruloplasmin causes direct oxidative stress on astrocytes. The intense immunolabelling of ferritin and Mn SOD most likely reflects a defensive response to iron-mediated oxidative stress. This study suggests that astrocytes play key roles in iron trafficking and the detoxification of iron-mediated free radicals at the blood-brain barrier and in the parenchyma in ACP brain. The antioxidative ability of astrocytes is one of their essential neuroprotective effects, and the decompensation of this ability may lead to secondary neuronal cell death in ACP.  相似文献   
8.
BACKGROUND AND OBJECTIVE: Hemodialysis (HD) is associated with restless legs syndrome (RLS) and periodic leg movements in sleep (PLMS), but the mechanisms underlying these relationships remain unclear. African-American HD patients have been reported previously to have a reduced likelihood of RLS. Alterations in iron metabolism, known to be a risk factor for idiopathic forms of RLS, could represent the basis for these racial differences. PATIENTS AND METHODS: In secondary data analyses from a previously published study, we examined raw and log-transformed values for plasma ferritin and polysomnographically recorded PLMS in Caucasian and African-American HD patients. RESULTS: African-American (n=36) HD patients had higher ferritin and lower PLMS than Caucasians (n=10). However, within the African-American population, ferritin levels were unrelated to PLMS. CONCLUSIONS: These results are compatible with previously reported racial differences in RLS to the extent that PLMS were less common in the African-American population. However, they suggest that if a differential genetic vulnerability underlies those racial differences, it may not manifest as a deficiency in iron metabolism, at least within the constraints of the marker of iron stores used here (e.g. serum ferritin) and in the specific population studied (hemodialysis). Future studies with larger, more representative samples of African-Americans and Caucasians will be required to replicate such differences.  相似文献   
9.
Objectives Subarachnoid hemorrhage (SAH) is a common cause of chronic hydrocephalus. Blood in the subarachnoid space is intracranially metabolized to bilirubin and iron, and free iron is thereafter detoxified by ferritin. However, no studies have reported the relationship between intracranial heme metabolism and chronic hydrocephalus after SAH. The goal of this prospective study was to clarify the relationship between intracranial heme metabolism and chronic hydrocephalus after SAH. Methods The authors measured the levels of bilirubin, iron and ferritin in the cerebrospinal fluid (CSF) of 70 consecutive patients with aneurysmal SAH of Fisher computed tomography Group III, and determined the relationship between these substances’ levels and hydrocephalus requiring ventriculoperitoneal shunting. Results The CSF concentrations of ferritin and inflammatory cells were significantly higher in shunted patients (n = 27) than in non-shunted patients (n = 43) on Days 3 and 4 (p<0.05 in ferritin and p<0.01 in inflammatory cells) and 11 to 14 (p<0.005 in ferritin) post-SAH. These results were independent of other clinical factors. The occurrence of chronic hydrocephalus was not affected by the extent of the intracranial heme metabolism in terms of the bilirubin and iron levels. Conclusions This is the first study to show that patients who subsequently had chronic hydrocephalus requiring CSF shunting were associated with higher CSF levels of ferritin in the acute stage of SAH. Higher CSF ferritin levels may not reflect the amount of blood in the subarachnoid space that was intracranially metabolized, but rather more intense subarachnoid inflammatory reactions which may cause chronic hydrocephalus after SAH. Received in revised form: 19 January 2006  相似文献   
10.
Hypertrophic cardiomyopathy is a common complication of Friedreich's ataxia (FRDA). Histological sections reveal abnormal cardiomyocytes, muscle fiber necrosis, reactive inflammation, and increased endomysial connective tissue. Scattered muscle fibers display perinuclear collections of minute iron-positive granules that lie in rows between myofibrils. Frataxin deficiency in FRDA causes mitochondrial iron dysmetabolism. We studied total iron and the iron-related proteins ferritin, mitochondrial ferritin, divalent metal transporter 1 (DMT1), and ferroportin in FRDA hearts by biochemical and histological techniques. Total iron in the left ventricular wall of FRDA patients (30.7+/-19.3 mg/100 g dry weight) was not significantly higher than normal (31.3+/-24.1 mg/100 g dry weight). Similarly, cytosolic holoferritin levels in FRDA hearts (230+/-172 microg/g wet weight) were not significantly elevated above normal (148+/-86 microg/g wet weight). The iron-positive granules exhibited immunoreactivity for cytosolic ferritin, mitochondrial ferritin, and ferroportin. Electron microscopy showed enhanced electron density of mitochondrial deposits after treatment with bismuth subnitrate supporting ferritin accumulation. The inflammatory cells in the endomysium were reactive for CD68, cytosolic ferritin, and the DMT1 isoform(s) translated from messenger ribonucleic acids containing iron-responsive elements (DMT1+). Progressive cardiomyopathy in FRDA is the likely result of iron-catalyzed mitochondrial damage followed by muscle fiber necrosis and a chronic reactive myocarditis.  相似文献   
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