Immunoproteasome deficiency results in age-dependent development of epilepsy

The immunoproteasome is a central protease complex required for optimal antigen presentation. Immunoproteasome activity is also associated with facilitating the degradation of misfolded and oxidized proteins, which prevents cellular stress. While extensively studied during diseases with increasing evidence suggesting a role for the immunoproteasome during pathological conditions including neurodegenerative diseases, this enzyme complex is believed to be mainly not expressed in the healthy brain. In this study, we show an age-dependent increase in polyubiquitination in the brains of wild-type mice, accompanied by an induction of immunoproteasomes, which was most prominent in neurons and microglia. In contrast, mice completely lacking immunoproteasomes (triple-knockout mice), displayed a strong increase in polyubiquitinated proteins already in the young brain and developed spontaneous epileptic seizures, beginning at the age of 6 months. Injections of kainic acid led to high epilepsy-related mortality of aged triple-knockout mice, confirming increased pathological hyperexcitability states. Notably, the expression of the immunoproteasome was reduced in the brains of patients suffering from epilepsy. In addition, the aged triple-knockout mice showed increased anxiety, tau hyperphosphorylation and degeneration of Purkinje cell population with the resulting ataxic symptoms and locomotion alterations. Collectively, our study suggests a critical role for the immunoproteasome in the maintenance of a healthy brain during ageing.

CPEB4-CLOCK crosstalk during temporal lobe epilepsy

OBJECTIVE

Posttranscriptional mechanisms are increasingly recognized as important contributors to the formation of hyperexcitable networks in epilepsy. Messenger RNA (mRNA) polyadenylation is a key regulatory mechanism governing protein expression by enhancing mRNA stability and translation. Previous studies have shown large-scale changes in mRNA polyadenylation in the hippocampus of mice during epilepsy development. The cytoplasmic polyadenylation element-binding protein CPEB4 was found to drive epilepsy-induced poly(A) tail changes, and mice lacking CPEB4 develop a more severe seizure and epilepsy phenotype. The mechanisms controlling CPEB4 function and the downstream pathways that influence the recurrence of spontaneous seizures in epilepsy remain poorly understood.

METHODS

Status epilepticus was induced in wild-type and CPEB4-deficient male mice via an intra-amygdala microinjection of kainic acid. CLOCK binding to the CPEB4 promoter was analyzed via chromatin immunoprecipitation assay and melatonin levels via high-performance liquid chromatography in plasma.

RESULTS

Here, we show increased binding of CLOCK to recognition sites in the CPEB4 promoter region during status epilepticus in mice and increased Cpeb4 mRNA levels in N2A cells overexpressing CLOCK. Bioinformatic analysis of CPEB4-dependent genes undergoing changes in their poly(A) tail during epilepsy found that genes involved in the regulation of circadian rhythms are particularly enriched. Clock transcripts displayed a longer poly(A) tail length in the hippocampus of mice post-status epilepticus and during epilepsy. Moreover, CLOCK expression was increased in the hippocampus in mice post-status epilepticus and during epilepsy, and in resected hippocampus and cortex of patients with drug-resistant temporal lobe epilepsy. Furthermore, CPEB4 is required for CLOCK expression after status epilepticus, with lower levels in CPEB4-deficient compared to wild-type mice. Last, CPEB4-deficient mice showed altered circadian function, including altered melatonin blood levels and altered clustering of spontaneous seizures during the day.

SIGNIFICANCE

Our results reveal a new positive transcriptional-translational feedback loop involving CPEB4 and CLOCK, which may contribute to the regulation of the sleep-wake cycle during epilepsy.

Anaplastic ganglioglioma - a diagnosis comprising several distinct tumour types

Anaplastic ganglioglioma is a rare tumour and diagnosis has been based on histological criteria. The 5^th edition of the World Health Organization Classification of Tumours of the Central Nervous System (CNS WHO) does not list anaplastic ganglioglioma as a distinct diagnosis due to lack of molecular data in previous publications AIM: We retrospectively compiled a cohort of 54 histologically diagnosed anaplastic gangliogliomas to explore whether the molecular profiles of these tumours represent a separate type or resolve into other entities METHODS: Samples were subjected to histological review, DNA methylation profiling and next generation sequencing. Morphologic and molecular data were summarised to an integrated diagnosis RESULTS: The majority of histologically diagnosed anaplastic gangliogliomas resolved into CNS WHO diagnoses of glial tumours, most commonly pleomorphic xanthoastrocytoma (16/54), glioblastoma, IDH wildtype and diffuse paediatric-type high-grade glioma, H3 wildtype and IDH wildtype (11 and 2/54) followed by low-grade glial or glioneuronal tumours including pilocytic astrocytoma, dysembryoplastic neuroepithelial tumour and diffuse leptomeningeal glioneuronal tumour (5/54), IDH mutant astrocytoma (4/54) and others (6/54). A subset of tumours (10/54) was not assignable to a CNS WHO diagnosis and common molecular profiles pointing to a separate entity were not evident CONCLUSION: In summary, we show that tumours histologically diagnosed as anaplastic ganglioglioma comprise a wide spectrum of CNS WHO tumour types with different prognostic and therapeutic implications. We therefore suggest assigning this designation with caution and recommend comprehensive molecular workup.

Polyadenylation of mRNA as a novel regulatory mechanism of gene expression in temporal lobe epilepsy

Temporal lobe epilepsy is the most common and refractory form of epilepsy in adults. Gene expression within affected structures such as the hippocampus displays extensive dysregulation and is implicated as a central pathomechanism. Post-transcriptional mechanisms are increasingly recognized as determinants of the gene expression landscape, but key mechanisms remain unexplored. Here we show, for first time, that cytoplasmic mRNA polyadenylation, one of the post-transcriptional mechanisms regulating gene expression, undergoes widespread reorganization in temporal lobe epilepsy. In the hippocampus of mice subjected to status epilepticus and epilepsy, we report >25% of the transcriptome displays changes in their poly(A) tail length, with deadenylation disproportionately affecting genes previously associated with epilepsy. Suggesting cytoplasmic polyadenylation element binding proteins (CPEBs) being one of the main contributors to mRNA polyadenylation changes, transcripts targeted by CPEBs were particularly enriched among the gene pool undergoing poly(A) tail alterations during epilepsy. Transcripts bound by CPEB4 were over-represented among transcripts with poly(A) tail alterations and epilepsy-related genes and CPEB4 expression was found to be increased in mouse models of seizures and resected hippocampi from patients with drug-refractory temporal lobe epilepsy. Finally, supporting an adaptive function for CPEB4, deletion of Cpeb4 exacerbated seizure severity and neurodegeneration during status epilepticus and the development of epilepsy in mice. Together, these findings reveal an additional layer of gene expression regulation during epilepsy and point to novel targets for seizure control and disease-modification in epilepsy.

MicroRNA-22 Controls Aberrant Neurogenesis and Changes in Neuronal Morphology After Status Epilepticus

Prolonged seizures (status epilepticus, SE) may drive hippocampal dysfunction and epileptogenesis, at least partly, through an elevation in neurogenesis, dysregulation of migration and aberrant dendritic arborization of newly-formed neurons. MicroRNA-22 was recently found to protect against the development of epileptic foci, but the mechanisms remain incompletely understood. Here, we investigated the contribution of microRNA-22 to SE-induced aberrant adult neurogenesis. SE was induced by intraamygdala microinjection of kainic acid (KA) to model unilateral hippocampal neuropathology in mice. MicroRNA-22 expression was suppressed using specific oligonucleotide inhibitors (antagomir-22) and newly-formed neurons were visualized using the thymidine analog iodo-deoxyuridine (IdU) and a green fluorescent protein (GFP)-expressing retrovirus to visualize the dendritic tree and synaptic spines. Using this approach, we quantified differences in the rate of neurogenesis and migration, the structure of the apical dendritic tree and density and morphology of dendritic spines in newly-formed neurons.SE resulted in an increased rate of hippocampal neurogenesis, including within the undamaged contralateral dentate gyrus (DG). Newly-formed neurons underwent aberrant migration, both within the granule cell layer and into ectopic sites. Inhibition of microRNA-22 exacerbated these changes. The dendritic diameter and the density and average volume of dendritic spines were unaffected by SE, but these parameters were all elevated in mice in which microRNA-22 was suppressed. MicroRNA-22 inhibition also reduced the length and complexity of the dendritic tree, independently of SE. These data indicate that microRNA-22 is an important regulator of morphogenesis of newly-formed neurons in adults and plays a role in supressing aberrant neurogenesis associated with SE.

Evaluation of the specificity of the central diagnostic criterion for chronic traumatic encephalopathy

INTRODUCTION

Chronic traumatic encephalopathy (CTE) is a postmortem diagnosis. Consensus postmortem, but not antemortem, diagnostic criteria have been established. A key factor in these criteria is evidence of phosphorylated-tau (p-tau) around sulcal vessels in the cortex. However, this sign has been observed anecdotally in a diverse range of neurodegenerative diseases (NDD). We therefore hypothesise that this criterion may lack specificity.

METHODS

To test this, we assessed patients with NDD, but no documented history of brain trauma, for sulcal p-tau. Tissue was retrieved from Dublin Brain Bank (known NDD n = 17; control with no diagnosed NDD n = 6; CTE n = 1), and slides were prepared from three sites with a predilection for trauma: superior frontal gyrus, temporal pole, and superior temporal gyrus. We stained the resulting anonymised slides with both hemotoxylin and eosin (H&E) and p-tau. Three neuropathologists, blinded to the clinical history and neuropathological diagnosis in each instance, evaluated each case for sulcal p-tau. We calculated the interrater agreement, using Fleiss's kappa, and the specificity of this neuropathological sign.

RESULTS

Sulcal p-tau was highly specific to diagnosed CTE cases (specificity 0.98), with moderate interrater agreement (κ = 0.45).

CONCLUSION

In conclusion, therefore, we observed sulcal p-tau to be a sign highly specific to CTE when compared with NDD cases in the absence of head trauma.

Temporal stability of MGMT promoter methylation in glioblastoma patients undergoing STUPP protocol

Epigenetic silencing of O-6-methylguanine-DNA methyltransferase (MGMT) promoter via methylation in a glioblastoma (GBM), has been correlated with a more favourable response to alkylating chemotherapeutic agents such as temozolomide. The use of global methylation surrogates such as Long Interspersed Nucleotide Element 1 (LINE1) may also be valuable in order to fully understand these highly heterogeneous tumours. In this study, we analysed both original and recurrent GBMs in 22 patients (i.e. 44 tumours), for both MGMT and LINE1 methylation status. In the 22 patients: 14 (63.6%) displayed MGMT methylation stability in the recurrent GBM versus 8 (36.4%), with instability of methylation status. No significant differences in overall and progression free survival was evident between these two groups. LINE1 methylation status remained stable for 12 (54.5%) of recurrent GBM patients versus 9 (41%) of the patients with instability in LINE1 methylation status (p = 0.02), resulting in an increase in overall survival of the stable LINE1 group (p = 0.04). The results obtained demonstrated major epigenetic instability of GBMs treated with temozolomide as part of the STUPP protocol. GBMs appear to undergo selective evolution post-treatment, and have the ability to recur with a newly reprogrammed epigenetic status. Selective targeting of the altered epigenomes in recurrent GBMs may facilitate the future development of both prognostic biomarkers and enhanced therapeutic strategies.

The significance of BRAF V600E mutation status discordance between primary cutaneous melanoma and brain metastases: The implications for BRAF inhibitor therapy

To compare BRAF V600E status of primary melanoma and brain metastases to assess for discordance by cross-sectional study, and to evaluate clinical implications on BRAF inhibitor therapy.Brain metastases are common in patients with advanced melanoma. Between 40% and 60% of melanomas demonstrate BRAF mutations, BRAF V600E being most common. Selective BRAF inhibitor therapy has shown improvement in outcome in patients with melanoma. It has been demonstrated that not all metastatic lesions carry the same BRAF mutation status as the primary, but the frequency in which discordance occurs remains unclear. Establishing this may have implications in the use of BRAF inhibitors in patients with melanoma brain metastases.Patients who underwent metastectomy for melanoma brain metastases were identified using our local histopathology database. A review of histology of the primary lesion and the metastasis was performed for each patient, assessing for BRAF mutation status discordance.Fourty-two patients who underwent a brain metastectomy following excision of a melanoma primary were identified over a 7-year period. Median survival was 9 months. The median Breslow thickness for the primary lesion was 3.4 mm. Six patients (14%) had discrepancy between the BRAF status of a melanoma primary and metastatic lesion. Of these 6 patients, 3 had a BRAF mutation positive primary with a BRAF mutation negative metastatic lesion, while the other 3 had a BRAF mutation negative primary with BRAF mutation positive metastasis.There is an important discordance rate in the BRAF mutation status of melanoma primaries versus brain metastases.

Brain biopsies requiring Creutzfeldt-Jakob disease precautions in the Republic of Ireland 2005-2016

AIMS

Creutzfeldt-Jakob disease (CJD) risk precautions are required when performing brain biopsies on patients with a dementing illness and in 'risk' groups. The impact on a diagnostic neuropathology service is considerable. We sought to determine if better case selection might reduce the necessity for application of CJD risk precautions.

METHODS

We reviewed the clinical information, contributory investigations and final neuropathologic diagnosis in a cohort of patients (n = 21), referred to the National CJD Surveillance Centre between January 1, 2005, and December 31, 2016.

RESULTS

Of this 21-patient cohort, five were positive for CJD, four belonged to the 'at risk of CJD' category requiring brain surgery, while the remaining 12 were referred to the National CJD Surveillance Unit with CJD as part of their differential diagnosis. CJD was confirmed in 5/21 (three sporadic [s]CJD, one variant [v]CJD and one iatrogenic [i] CJD). CJD was clinically probable in 4/5 proven CJD patients (80%). The patients (n = 4) in the 'at risk of CJD' group were diagnosed with tumour (n = 2), inflammation (n = 1) and non-specific changes (n = 1). Of the remaining 12 patients (in whom CJD was included in the differential diagnosis), the final neuropathologic diagnoses included tumour (n = 2), neurodegenerative (n = 2), inflammatory (n = 1), metabolic (n = 2), vascular (n = 2) and non-specific gliosis (n = 3).

CONCLUSIONS

More often than not, the clinical suspicion of CJD was not borne out by the final neuropathological diagnosis. Failure by clinicians to adhere to the recommended CJD investigation algorithm impacts adversely on the neuropathology workload and causes unnecessary concern among operating theatre, laboratory and nursing personnel.

Expression and function of the metabotropic purinergic P2Y receptor family in experimental seizure models and patients with drug-refractory epilepsy

OBJECTIVE

ATP is released into the extracellular space during pathologic processes including increased neuronal firing. Once released, ATP acts on P2 receptors including ionotropic P2X and metabotropic P2Y receptors, resulting in changes to glial function and neuronal network excitability. Evidence suggests an involvement of P2Y receptors in the pathogenesis of epilepsy, but there has been no systematic effort to characterize the expression and function of the P2Y receptor family during seizures and in experimental and human epilepsy.

METHODS

Status epilepticus was induced using either intra-amygdala kainic acid or pilocarpine to characterize the acute- and long-term changes in hippocampal P2Y expression. P2Y expression was also investigated in brain tissue from patients with temporal lobe epilepsy. Finally, we analyzed the effects of two specific P2Y agonists, ADP and UTP, on seizure severity and seizure-induced cell death.

RESULTS

Both intra-amygdala kainic acid and pilocarpine-induced status epilepticus increased the transcription of the uracil-sensitive P2Y receptors P2ry₂ , P2ry₄ , and P2ry₆ and decreased the transcription of the adenine-sensitive P2Y receptors P2ry₁ , P2ry₁₂ , P2ry₁₃ . Protein levels of P2Y₁ , P2Y₂ , P2Y₄ , and P2Y₆ were increased after status epilepticus, whereas P2Y₁₂ expression was decreased. In the chronic phase, P2ry₁ , P2ry₂ , and P2ry₆ transcription and P2Y₁ , P2Y₂ , and P2Y₁₂ protein levels were increased with no changes for the other P2Y receptors. In hippocampal samples from patients with temporal lobe epilepsy, P2Y₁ and P2Y₂ protein expression was increased, whereas P2Y₁₃ levels were lower. Demonstrating a functional contribution of P2Y receptors to seizures, central injection of ADP exacerbated seizure severity, whereas treatment with UTP decreased seizure severity during status epilepticus in mice.

SIGNIFICANCE

The present study is the first to establish the specific hippocampal expression profile and function of the P2Y receptor family after experimental status epilepticus and in human temporal lobe epilepsy and offers potential new targets for seizure control and disease modification.

A microRNA-129-5p/Rbfox crosstalk coordinates homeostatic downscaling of excitatory synapses

Synaptic downscaling is a homeostatic mechanism that allows neurons to reduce firing rates during chronically elevated network activity. Although synaptic downscaling is important in neural circuit development and epilepsy, the underlying mechanisms are poorly described. We performed small RNA profiling in picrotoxin (PTX)-treated hippocampal neurons, a model of synaptic downscaling. Thereby, we identified eight microRNAs (miRNAs) that were increased in response to PTX, including miR-129-5p, whose inhibition blocked synaptic downscaling in vitro and reduced epileptic seizure severity in vivo Using transcriptome, proteome, and bioinformatic analysis, we identified the calcium pump Atp2b4 and doublecortin (Dcx) as miR-129-5p targets. Restoring Atp2b4 and Dcx expression was sufficient to prevent synaptic downscaling in PTX-treated neurons. Furthermore, we characterized a functional crosstalk between miR-129-5p and the RNA-binding protein (RBP) Rbfox1. In the absence of PTX, Rbfox1 promoted the expression of Atp2b4 and Dcx. Upon PTX treatment, Rbfox1 expression was downregulated by miR-129-5p, thereby allowing the repression of Atp2b4 and Dcx. We therefore identified a novel activity-dependent miRNA/RBP crosstalk during synaptic scaling, with potential implications for neural network homeostasis and epileptogenesis.

RNA sequencing of synaptic and cytoplasmic Upf1-bound transcripts supports contribution of nonsense-mediated decay to epileptogenesis

The nonsense mediated decay (NMD) pathway is a critical surveillance mechanism for identifying aberrant mRNA transcripts. It is unknown, however, whether the NMD system is affected by seizures in vivo and whether changes confer beneficial or maladaptive responses that influence long-term outcomes such the network alterations that produce spontaneous recurrent seizures. Here we explored the responses of the NMD pathway to prolonged seizures (status epilepticus) and investigated the effects of NMD inhibition on epilepsy in mice. Status epilepticus led to increased protein levels of Up-frameshift suppressor 1 homolog (Upf1) within the mouse hippocampus. Upf1 protein levels were also higher in resected hippocampus from patients with intractable temporal lobe epilepsy. Immunoprecipitation of Upf1-bound RNA from the cytoplasmic and synaptosomal compartments followed by RNA sequencing identified unique populations of NMD-associated transcripts and altered levels after status epilepticus, including known substrates such as Arc as well as novel targets including Inhba and Npas4. Finally, long-term video-EEG recordings determined that pharmacologic interference in the NMD pathway after status epilepticus reduced the later occurrence of spontaneous seizures in mice. These findings suggest compartment-specific recruitment and differential loading of transcripts by NMD pathway components may contribute to the process of epileptogenesis.

Potent Anti-seizure Effects of Locked Nucleic Acid Antagomirs Targeting miR-134 in Multiple Mouse and Rat Models of Epilepsy

Current anti-epileptic drugs (AEDs) act on a limited set of neuronal targets, are ineffective in a third of patients with epilepsy, and do not show disease-modifying properties. MicroRNAs are small noncoding RNAs that regulate levels of proteins by post-transcriptional control of mRNA stability and translation. MicroRNA-134 is involved in controlling neuronal microstructure and brain excitability and previous studies showed that intracerebroventricular injections of locked nucleic acid (LNA), cholesterol-tagged antagomirs targeting microRNA-134 (Ant-134) reduced evoked and spontaneous seizures in mouse models of status epilepticus. Translation of these findings would benefit from evidence of efficacy in non-status epilepticus models and validation in another species. Here, we report that electrographic seizures and convulsive behavior are strongly reduced in adult mice pre-treated with Ant-134 in the pentylenetetrazol model. Pre-treatment with Ant-134 did not affect the severity of status epilepticus induced by perforant pathway stimulation in adult rats, a toxin-free model of acquired epilepsy. Nevertheless, Ant-134 post-treatment reduced the number of rats developing spontaneous seizures by 86% in the perforant pathway stimulation model and Ant-134 delayed epileptiform activity in a rat ex vivo hippocampal slice model. The potent anticonvulsant effects of Ant-134 in multiple models may encourage pre-clinical development of this approach to epilepsy therapy.

Rapid Clinical Course of Multiple Metastatic Cerebral Angiosarcoma

Central nervous system (CNS) angiosarcoma, both primary and secondary, is an exceptionally rare malignant tumor. The behaviour of angiosarcoma is one of rapid progression with early metastatic spread but as with all sarcomas, the primary site may not clinically evident by the time metastases develop. Identification of the primary site of origin is masked by the carpet-like growth pattern that may occur in the left atrium, the most frequently encountered primary site for angiosarcoma. This rare tumor presents many diagnostic challenges. We describe the clinical and neuropathologic features of two patients with angiosarcoma of the brain and review the previously published cases described to date.

Autoregulated paracellular clearance of amyloid-β across the blood-brain barrier

The blood-brain barrier (BBB) is essential for maintaining brain homeostasis and protecting neural tissue from damaging blood-borne agents. The barrier is characterized by endothelial tight junctions that limit passive paracellular diffusion of polar solutes and macromolecules from blood to brain. Decreased brain clearance of the neurotoxic amyloid-β (Aβ) peptide is a central event in the pathogenesis of Alzheimer's disease (AD). Whereas transport of Aβ across the BBB can occur via transcellular endothelial receptors, the paracellular movement of Aβ has not been described. We show that soluble human Aβ(1-40) monomers can diffuse across the paracellular pathway of the BBB in tandem with a decrease in the tight junction proteins claudin-5 and occludin in the cerebral vascular endothelium. In a murine model of AD (Tg2576), plasma Aβ(1-40) levels were significantly increased, brain Aβ(1-40) levels were decreased, and cognitive function was enhanced when both claudin-5 and occludin were suppressed. Furthermore, Aβ can cause a transient down-regulation of claudin-5 and occludin, allowing for its own paracellular clearance across the BBB. Our results show, for the first time, the involvement of the paracellular pathway in autoregulated Aβ movement across the BBB and identify both claudin-5 and occludin as potential therapeutic targets for AD. These findings also indicate that controlled modulation of tight junction components at the BBB can enhance the clearance of Aβ from the brain.

Migrating partial seizures of infancy: expansion of the electroclinical, radiological and pathological disease spectrum

Migrating partial seizures of infancy, also known as epilepsy of infancy with migrating focal seizures, is a rare early infantile epileptic encephalopathy with poor prognosis, presenting with focal seizures in the first year of life. A national surveillance study was undertaken in conjunction with the British Paediatric Neurology Surveillance Unit to further define the clinical, pathological and molecular genetic features of this disorder. Fourteen children with migrating partial seizures of infancy were reported during the 2 year study period (estimated prevalence 0.11 per 100,000 children). The study has revealed that migrating partial seizures of infancy is associated with an expanded spectrum of clinical features (including severe gut dysmotility and a movement disorder) and electrographic features including hypsarrhythmia (associated with infantile spasms) and burst suppression. We also report novel brain imaging findings including delayed myelination with white matter hyperintensity on brain magnetic resonance imaging in one-third of the cohort, and decreased N-acetyl aspartate on magnetic resonance spectroscopy. Putaminal atrophy (on both magnetic resonance imaging and at post-mortem) was evident in one patient. Additional neuropathological findings included bilateral hippocampal gliosis and neuronal loss in two patients who had post-mortem examinations. Within this cohort, we identified two patients with mutations in the newly discovered KCNT1 gene. Comparative genomic hybridization array, SCN1A testing and genetic testing for other currently known early infantile epileptic encephalopathy genes (including PLCB1 and SLC25A22) was non-informative for the rest of the cohort.

CHOP regulates the p53-MDM2 axis and is required for neuronal survival after seizures

Hippocampal sclerosis is a frequent pathological finding in patients with temporal lobe epilepsy and can be caused by prolonged single or repeated brief seizures. Both DNA damage and endoplasmic reticulum stress have been implicated as underlying molecular mechanisms in seizure-induced brain injury. The CCAAT/enhancer-binding protein homologous protein (CHOP) is a transcriptional regulator induced downstream of DNA damage and endoplasmic reticulum stress, which can promote or inhibit apoptosis according to context. Recent work has proposed inhibition of CHOP as a suitable neuroprotective strategy. Here, we show that transcript and protein levels of CHOP increase in surviving subfields of the hippocampus after prolonged seizures (status epilepticus) in mouse models. CHOP was also elevated in the hippocampus from epileptic mice and patients with pharmacoresistant epilepsy. The hippocampus of CHOP-deficient mice was much more vulnerable to damage in mouse models of status epilepticus. Moreover, compared with wild-type animals, CHOP-deficient mice subject to status epilepticus developed more spontaneous seizures, displayed protracted hippocampal neurodegeneration and a deficit in a hippocampus-dependent object-place recognition task. The absence of CHOP was associated with a supra-maximal induction of p53 after status epilepticus, and inhibition of p53 abolished the cell death-promoting consequences of CHOP deficiency. The protective effect of CHOP could be partly explained by activating transcription of murine double minute 2 that targets p53 for degradation. These data demonstrate that CHOP is required for neuronal survival after seizures and caution against inhibition of CHOP as a neuroprotective strategy where excitotoxicity is an underlying pathomechanism.

Human anti-Aβ IgGs target conformational epitopes on synthetic dimer assemblies and the AD brain-derived peptide

Soluble non-fibrillar assemblies of amyloid-beta (Aβ) and aggregated tau protein are the proximate synaptotoxic species associated with Alzheimer's disease (AD). Anti-Aβ immunotherapy is a promising and advanced therapeutic strategy, but the precise Aβ species to target is not yet known. Previously, we and others have shown that natural human IgGs (NAbs) target diverse Aβ conformers and have therapeutic potential. We now demonstrate that these antibodies bound with nM avidity to conformational epitopes on plate-immobilized synthetic Aβ dimer assemblies, including synaptotoxic protofibrils, and targeted these conformers in solution. Importantly, NAbs also recognized Aβ extracted from the water-soluble phase of human AD brain, including species that migrated on denaturing PAGE as SDS-stable dimers. The critical reliance on Aβ's conformational state for NAb binding, and not a linear sequence epitope, was confirmed by the antibody's nM reactivity with plate-immobilized protofibrills, and weak uM binding to synthetic Aβ monomers and peptide fragments. The antibody's lack of reactivity against a linear sequence epitope was confirmed by our ability to isolate anti-Aβ NAbs from intravenous immunoglobulin using affinity matrices, immunoglobulin light chain fibrils and Cibacron blue, which had no sequence similarity with the peptide. These findings suggest that further investigations on the molecular basis and the therapeutic/diagnostic potential of anti-Aβ NAbs are warranted.

Alzheimer's disease brain-derived amyloid-β-mediated inhibition of LTP in vivo is prevented by immunotargeting cellular prion protein

Synthetic amyloid-β protein (Aβ) oligomers bind with high affinity to cellular prion protein (PrP(C)), but the role of this interaction in mediating the disruption of synaptic plasticity by such soluble Aβ in vitro is controversial. Here we report that intracerebroventricular injection of Aβ-containing aqueous extracts of Alzheimer's disease (AD) brain robustly inhibits long-term potentiation (LTP) without significantly affecting baseline excitatory synaptic transmission in the rat hippocampus in vivo. Moreover, the disruption of LTP was abrogated by immunodepletion of Aβ. Importantly, intracerebroventricular administration of antigen-binding antibody fragment D13, directed to a putative Aβ-binding site on PrP(C), prevented the inhibition of LTP by AD brain-derived Aβ. In contrast, R1, a Fab directed to the C terminus of PrP(C), a region not implicated in binding of Aβ, did not significantly affect the Aβ-mediated inhibition of LTP. These data support the pathophysiological significance of SDS-stable Aβ dimer and the role of PrP(C) in mediating synaptic plasticity disruption by soluble Aβ.

Percutaneous cryoablation of renal masses >or=3 cm: efficacy and safety in treatment of 108 patients

PURPOSE

To evaluate our single institution experience with percutaneous cryoablation of renal masses >or=3 cm in diameter for complications and short-term outcomes.

PATIENTS AND METHODS

Between March 2003 and February 2009, 108 patients with 110 renal masses >or=3 cm in diameter were treated with percutaneous cryoablation therapy. Technical success of the ablation procedure, complications, and evidence for local tumor recurrence were evaluated for each patient.

RESULTS

Average maximal renal tumor diameter was 4.1 cm (range 3.0-8.3 cm; standard deviation 1.1 cm). A single cryoablation procedure was performed for treatment of each patient. A technically successful ablation was achieved for 107 of 110 (97%) tumors. The three technical failures all resulted from incomplete cryoablation of the deepest margin of a centrally located renal tumor. A total of 9 severe adverse events occurred in six patients, resulting in an 8% major complication rate. Two patients in whom major complications developed were part of the group of only four patients for whom ablation was performed for tumors > 7 cm in diameter. There were no procedural-related deaths. No evidence for local tumor recurrence was identified in any patients with follow-up contrast-enhanced CT or MRI obtained 3 months or longer from the time of the ablation. Follow-up in these patients averaged 15 months (range 3-42 mos).

CONCLUSION

Percutaneous cryoablation of renal masses >or=3 cm in diameter can be performed with high technical success and low complication rates. Extra scrutiny is needed during cryoablation of central renal masses to make sure the ablation zone extends to include the deepest margin of the tumor. Although our experience is limited, percutaneous cryoablation of renal tumors > 7 cm in diameter may be associated with increased complications. The lack of local renal tumor recurrences seen in this study on short-term follow-up is encouraging, but long-term follow-up remains necessary to ensure treatment durability.

Recessive mutations in RYR1 are a common cause of congenital fiber type disproportion

The main histological abnormality in congenital fiber type disproportion (CFTD) is hypotrophy of type 1 (slow twitch) fibers compared to type 2 (fast twitch) fibers. To investigate whether mutations in RYR1 are a cause of CFTD we sequenced RYR1 in seven CFTD families in whom the other known causes of CFTD had been excluded. We identified compound heterozygous changes in the RYR1 gene in four families (five patients), consistent with autosomal recessive inheritance. Three out of five patients had ophthalmoplegia, which may be the most specific clinical indication of mutations in RYR1. Type 1 fibers were at least 50% smaller, on average, than type 2 fibers in all biopsies. Recessive mutations in RYR1 are a relatively common cause of CFTD and can be associated with extreme fiber size disproportion.

Role of intraarterial embolization before cryoablation of large renal tumors: a pilot study

A retrospective review of patients who underwent percutaneous cryoablations of renal tumors (> or = 5 cm) with/without previous selective intraarterial embolization from March 2003 to January 2008 was performed to compare periprocedural complications. Of 129 treated tumors, 11 (8.5%) were larger than 5 cm. One patient was lost to follow-up. Of the remaining 10 follow-up patients, four (40%) underwent selective intraarterial tumor embolization before cryoablation. The mean hematoma volume in patients who underwent embolization before cryoablation (n = 4) was 18.3 mL +/- 25.9, whereas that in patients who underwent cryoablation alone (n = 6) was 357.3 mL +/- 460.9 (P< .01). Only one patient required transfusion and prolonged hospitalization. Combination therapy can provide a decrease in postprocedural cryoablation-related hemorrhage.

Vacuolar leucoencephalopathy and pulvinar sign in association with coeliac disease

Several neurological disorders have been associated with coeliac disease, including epilepsy, ataxia and neuropathy. Here we report a rare case of white matter disease in a 55-year-old man with coeliac disease. He presented with anxiety, headache and left upper limb jerking. He subsequently developed epilepsy and brain MRI revealed diffuse white matter abnormality. He died 6 months after presentation due to status epilepticus and sepsis. Brain biopsy demonstrated vacuolar leucoencephalopathy with no evidence of vCJD. An extensive clinical screen excluded infectious, inflammatory and para-neoplastic causes for this condition. Coeliac disease may be causally associated with vacuolar leucoencephalopathy in this case.

Adult-onset nemaline myopathy presenting as respiratory failure

Nemaline myopathy is a rare congenital myopathy that generally presents in childhood. We report a case of a 44-year-old man who presented with severe hypoxic hypercapnic respiratory failure as the initial manifestation of nemaline myopathy. After starting noninvasive ventilation, his pulmonary function test results improved substantially, and over the 4 years since diagnosis his respiratory function remained stable. There are few reported cases of respiratory failure in patients with adult-onset nemaline myopathy, and the insidious onset in this case is even more unusual. This case highlights the varied presenting features of adult-onset nemaline myopathy and that noninvasive ventilation improves respiratory function.

Radiofrequency ablation of renal tumors in the solitary kidney

OBJECTIVES

Radiofrequency ablation (RFA) is a minimally invasive therapy aimed at maximal preservation of renal function in the nonsurgical renal mass patient. We evaluate our experience with RFA of renal tumors in the solitary kidney.

PATIENTS AND METHODS

A retrospective review of all patients with a solitary kidney treated with RFA for renal mass was performed. Two radiologists reviewed all images. From December 2001 to June 2006, 55 renal tumors were treated with RFA in 30 patients with a solitary kidney. Percutaneous approach was used in 44 tumors (26 patients) and intraoperative open approach in 11 tumors (4 patients). Average mass size was 2.0 cm (1.2-5.4). Biopsy performed prior to ablation in 14 tumors showed renal cell carcinoma in 12 (86%) and was non diagnostic in 2 (14%).

RESULTS

There were no major post procedural complications. Initial technical success was noted in 98% of tumors in 97% of patients. Average follow-up with contrast enhanced CT or MRI was 25 months (3-47) in 26 patients (50 tumors) and showed local tumor control in 100%. No difference in preoperative and postoperative calculated creatinine clearance was noted (p = 0.072). There was no difference in systolic (p = 0.102) and diastolic (p = 0.790) blood pressure pre and post ablation.

CONCLUSIONS

RFA of renal masses in the solitary kidney appears to be a safe, minimally invasive alternative to open surgical resection in properly selected patients. Local tumor control was achieved with no adverse effects on renal function and blood pressure in this series.

Percutaneous cryoablation of large renal masses: technical feasibility and short-term outcome

OBJECTIVE

This retrospective study was performed to assess the feasibility, safety, and short-term outcome of percutaneous cryoablation of large solid renal tumors.

MATERIALS AND METHODS

We reviewed 40 percutaneous cryoablation procedures performed on 40 patients with renal tumors 3 cm in diameter or larger. All patients underwent cryoablation with CT monitoring. Technical success was defined by extension of the ice ball beyond the tumor margin and postablation imaging findings of no contrast enhancement in the area encompassing the original tumor. Complications meeting grade 3 of the National Cancer Institute Common Terminology Criteria for Adverse Events were recorded.

RESULTS

Mean +/- SD tumor diameter was 4.2 +/- 1.1 cm (range, 3.0-7.2 cm). Technical success was achieved in 38 (95%) of 40 cryoablation procedures. There was one grade 3 adverse event (3% rate of significant complications). Follow-up images obtained 3 months or longer (mean, 9 +/- 6 months; range, 3-22 months) after ablation were available for 26 (65%) of the 40 patients. No local tumor recurrence or tumor progression was found.

CONCLUSION

Percutaneous cryoablation of renal tumors measuring 3 cm or larger is technically feasible and relatively safe. Short-term follow-up results are encouraging, although long-term follow-up is necessary to assess true treatment efficacy.

Percutaneous cryoablation of 40 solid renal tumors with US guidance and CT monitoring: initial experience

PURPOSE

To retrospectively determine the safety and effectiveness of percutaneous cryoablation, monitored with computed tomography (CT), for the treatment of solid renal masses.

MATERIALS AND METHODS

This study was compliant with the Health Insurance Portability and Accountability Act and had institutional review board approval; informed consent was waived. From March 12, 2003, through August 4, 2005, 23 men and 17 women (mean age, 76 years +/- 9.7 [standard deviation]; range, 53-92 years), each with a single renal tumor, underwent one percutaneous cryoablation treatment session that combined ultrasonographic (US) guidance and CT monitoring. Technical success was defined as extension of the visible ice ball 5 mm beyond the tumor margin. Local tumor progression was defined as any tumor with intralesional enhancement or a serial increase in tumor size when compared with that on images obtained immediately after ablation. Tumor characteristics, complications, and follow-up were evaluated.

RESULTS

The maximum diameter of the 40 treated lesions ranged from 1.5 to 7.2 cm (mean, 3.4 cm +/- 1.3). Twenty (50%) of 40 tumors were 3 cm or larger in diameter. Nineteen tumors (48%) extended into the renal sinus fat. One complication (2%) conformed to a grade 3 event, as determined with the Common Terminology Criteria for Adverse Events (version 3.0) of the National Cancer Institute; the overall complication rate was 8%. Thirty-eight (95%) of 40 cryoablation procedures were technically successful. Twenty-nine patients underwent follow-up (mean, 8.0 months +/- 4.3; range, 1.2-18.4 months); no local tumor recurrence was found.

CONCLUSION

Percutaneous cryoablation with US guidance and CT monitoring is safe and effective for the treatment of solid renal tumors. Longer follow-up should provide further proof of the effectiveness of this technique.

Painful metastases involving bone: percutaneous image-guided cryoablation--prospective trial interim analysis

PURPOSE

To prospectively determine the safety and effectiveness of percutaneous cryoablation for the reduction of pain, improvement in the activities of daily life, and reduction in the use of analgesic medications for patients with painful metastatic lesions involving bone.

MATERIALS AND METHODS

This study was compliant with HIPAA and was approved by the institutional review board. Written informed consent was obtained. During 18 months, 14 patients (eight men, six women; age range, 21-72 years; mean age, 54 years) with one or two painful metastatic lesions involving bone, with a score of 4 or greater out of 10 for worst pain in a 24-hour period, and who did not respond to or refused conventional radiation treatment or chemotherapy were treated with percutaneous cryoablation. Patient response was measured with the Brief Pain Inventory, and analgesic use was recorded before and after the procedure at days 1 and 4, weekly for 4 weeks, and then every other week for a total of 6 months. Complications were monitored. Analysis of the primary end points was undertaken with paired comparison procedures by using paired t tests across individual time points supplemented with repeated measures analysis of variance.

RESULTS

Treated lesions were 1-11 cm in diameter. Before cryoablation, the mean score for worst pain in a 24-hour period was 6.7 of 10; the score decreased to 3.8 (P = .003) 4 weeks after treatment. Mean pain interference with activities of daily living was 5.5 of 10 before treatment and decreased to 3.2 (P = .004) 4 weeks after treatment. All eight (100%) patients (exact 95% binomial confidence interval: 63%, 100%) for whom narcotics were prescribed prior to the procedure reported a reduction in these medications after cryoablation. No serious complications were observed.

CONCLUSION

Percutaneous cryoablation is a safe and effective method for palliation of pain due to metastatic disease involving bone.

Relapsing granulomatous angiitis of the central nervous system in a patient while in remission from Hodgkin lymphoma

We present a patient with granulomatous angiitis of the central nervous system (GANS) and Hodgkin lymphoma. His GANS resolved with treatment for the lymphoma, but then reactivated six months later in the absence of activate lymphoma. He made a full neurological recovery after treatment with reducing oral prednisolone over one year. This case indicates that prolonged use of steroids may be necessary to treat GANS in this setting and that it can run a course independent of the Hodgkin lymphoma.

Primary cerebellopontine angle craniopharyngioma in a patient with Gardner syndrome

✓The authors report on the case of a craniopharyngioma arising in the cerebellopontine angle (CPA) in a patient with Gardner syndrome. Although familial adenomatous polyposis (FAP) is associated with intracranial neoplasms, the current case is only the third reported craniopharyngioma in a patient with Gardner syndrome. Two of these tumors, including that of the current case, originated in the CPA, an unusual location for craniopharyngiomas. The literature concerning FAP and its associations with intracranial neoplasia, as well as the pathogenesis of craniopharyngiomas in the posterior fossa, is discussed.

Malignant Hypertension during Cryoablation of an Adrenal Gland Tumor

The authors report a case of hypertensive crisis during cryoablation of an adrenal metastasis. This case is of particular interest not only because of the nature of the complication but also because of the timing of the hypertensive crisis. Based on their observations, the authors suggest that it may be prudent to pretreat this patient population with alpha-adrenergic blocking medications (eg, phenoxybenzamine), as is typically done for patients with neuroendocrine tumors such as pheochromocytoma. Preemptive intervention with these medications requires close collaboration between radiology and anesthesia care teams.

Breast lesions: evaluation with US strain imaging--clinical experience of multiple observers

PURPOSE

To prospectively determine the accuracy of using an ultrasonographic (US) strain imaging technique known as lesion size comparison to differentiate benign from malignant breast lesions.

MATERIALS AND METHODS

Institutional Review Board approval and patient informed consent were obtained for this HIPPA-compliant study. US strain imaging was performed prospectively for 89 breast lesions in 88 patients. Lesions were imaged by using freehand compression and a real-time strain imaging algorithm. Five observers obtained manual measurements of lesion height, width, and area from B-mode and strain images. By using these size measurements, individual observer and group performances were assessed by using the area under the receiver operating characteristic curve (A(z)). The performance of a single size parameter versus that of a combination of size parameters was evaluated by using univariate and multivariate logistic regression.

RESULTS

Group A(z) values showed that width ratio and area ratio yielded the best results for differentiating benign and malignant breast lesions, and they were not statistically different from one another (P = .499). For the group, the performance of area and width, which was superior to that of height and aspect ratio, was statistically significant for all cases (P < .011) except for those that compared area with aspect ratio (P = .118). By using a group threshold of 1.04 for width ratio and 1.13 for area ratio, the sensitivity and specificity of the technique were 96% and 21%, respectively, for width and 96% and 24%, respectively, for area. The best observer achieved a sensitivity of 96% and a specificity of 61% by using the area ratio. For all but one observer, combined size parameters did not improve observer performance (P > .258). Significant interobserver performance variability was observed (P < .001).

CONCLUSION

Results suggest that US strain imaging has the potential to aid diagnosis of breast lesions. However, manually tracing lesion boundaries for size ratio differentiation in a busy clinical setting did not match the diagnostic performance levels previously reported. Focusing on measurements of lesion width, along with additional observer training or automated processes, may yield a suitable method for routine clinical application.

Image-guided ablation of painful metastatic bone tumors: a new and effective approach to a difficult problem

Painful skeletal metastases are a common problem in cancer patients. Although external beam radiation therapy is the current standard of care for cancer patients who present with localized bone pain, 20-30% of patients treated with this modality do not experience pain relief, and few further options exist for these patients. For many patients with painful metastatic skeletal disease, analgesics remain the only alternative treatment option. Recently, image-guided percutaneous methods of tumor destruction have proven effective for treatment of this difficult problem. This review describes the application, limitations, and effectiveness of percutaneous ablative methods including ethanol, methyl methacrylate, laser-induced interstitial thermotherapy (LITT), cryoablation, and percutaneous radiofrequency ablation (RFA) for palliation of painful skeletal metastases.

Intraperitoneal drop metastasis after radiofrequency ablation of pararenal tumor recurrences

We report the case of a 66-year-old woman who developed intraperitoneal drop metastasis after radiofrequency ablation of recurrent renal cell carcinoma. This patient had undergone multiple nephron-sparing procedures, including radiofrequency ablation to treat local recurrences. At routine follow-up, she was noted to have two intraperitoneal drop metastases, one in the right paracolic gutter and the other in the cul-de-sac of Douglas. The metastases were treated with complete surgical resection. To our knowledge, this is the first reported case of drop metastasis after radiofrequency ablation, drawing attention to the potential complications of this new treatment modality.

Treatment of neuroendocrine cancer metastatic to the liver: the role of ablative techniques

Carcinoid tumors and islet cell neoplasms are neuroendocrine neoplasms with indolent patterns of growth and association with bizarre hormone syndromes. These tumors behave in a relatively protracted and predictable manner, which allows for multiple therapeutic options. Even in the presence of hepatic metastases, the standard of treatment for neuroendocrine malignancy is surgery, either with curative intent or for tumor cytoreduction, i.e., resection of 90% or more of the tumor volume. Image-guided ablation, as either an adjunct to surgery or a primary treatment modality, can be used to treat neuroendocrine cancer metastatic to the liver. Image-guided ablative techniques, including radiofrequency ablation, alcohol injection, and cryoablation, can be used in selected patients to debulk hepatic tumors and improve patient symptoms. Although long-term follow-up data are not available, the surgical literature indicates that significant ablative debulking may improve patient survival. In this review, we discuss metastatic neuroendocrine disease and its treatment options, especially image-guided ablative techniques.

Fatal toxic leukoencephalopathy: clinical, radiological, and necropsy findings in two patients

BACKGROUND

Toxic leukoencephalopathy has been described with inhalation and intravenous consumption of heroin and cocaine. The clinical picture varies widely but the imaging and histological features are characteristic. Magnetic resonance imaging (MRI) typically reveals diffuse bihemispheric white matter lesions. Histologically there is extensive spongiform degeneration of the cerebral white matter.

OBJECTIVE

To report two cases of fatal toxin associated leukoencephalopathy, along with detailed imaging and neuropathological studies.

RESULTS

MRI revealed diffuse white matter changes. Histologically there was widespread confluent vacuolar degeneration of the deep white matter. In both cases, there was sparing of the brain stem and cerebellar white matter. There was evidence of severe and extensive axonal injury.

CONCLUSIONS

This pattern of radiological involvement and histological findings has not previously been reported and may reflect the presence of a yet unidentified impurity.