Mechanisms underlying Andersen's syndrome pathology in skeletal muscle are revealed in human myotubes

Andersen's syndrome is a rare disorder that has been defined with a triad: periodic paralysis, cardiac arrhythmia, and development anomalies. Muscle weakness has been reported in two-thirds of the patients. KCNJ2 remains the only gene linked to Andersen's syndrome; this gene encodes for the α-subunit of the strong inward-rectifier K+ channel Kir2.1. Several studies have shown that Andersen's syndrome mutations lead to a loss of function of the K+ channel activity in vitro. However, ex vivo studies on isolated patient muscle tissue have not been reported. We have performed muscle biopsies of controls and patients presenting with clinically and genetically defined Andersen's syndrome disorder. Myoblasts were cultured and characterized morphologically and functionally using the whole cell patch-clamp technique. No morphological difference was observed between Andersen's syndrome and control myoblasts at each passage of the cell culture. Cellular proliferation and viability were quantified in parallel with direct cell counts and showed no difference between control and Andersen's syndrome patients. Moreover, our data show no significant difference in myoblast fusion index among Andersen's syndrome and control patients. Current recordings carried out on myotubes revealed the absence of an inwardly rectifying Ba2+-sensitive current in affected patient cells. One consequence of the Ik1 current loss in Andersen's syndrome myotubes is a shift of the resting membrane potential toward depolarizing potentials. Our data describe for the first time the functional consequences of Andersen's syndrome mutations ex vivo and provide clues to the K+ channel pathophysiology in skeletal muscle.

Multiparametric differentiation of posterior fossa tumors in children using diffusion-weighted imaging and short echo-time 1H-MR spectroscopy

PURPOSE

To assess the combined value of diffusion-weighted imaging (DWI) and proton magnetic resonance spectroscopy (1H-MRS) in differentiating medulloblastoma, ependymoma, pilocytic astrocytoma, and infiltrating glioma in a pediatric population.

MATERIALS AND METHODS

A total of 17 children with untreated posterior fossa tumors (seven medulloblastoma, four infiltrating glioma, two ependymoma, and four pilocytic astrocytoma), were investigated with conventional MRI, DWI, and MRS using a single-voxel technique. Within the nonnecrotic tumor core, apparent diffusion coefficient (ADC) values using a standardized region of interest (ROI) were retrieved. Quantification of water signal and analysis of metabolite signals from MRS measurements in the same tumorous area were reviewed using multivariant linear discriminant analysis.

RESULTS

Combination of ADC values and metabolites, which were normalized using water as an internal standard, allowed discrimination between the four tumor groups with a likelihood below 1 x 10(-9). Positive predictive value was 1 in all cases. Tumors could not be discriminated when using metabolite ratios or ADC values alone, nor could they be differentiated using creatine (Cr) as an internal reference even in combination with ADC values.

CONCLUSION

Linear discriminant analysis using DWI and MRS using water as internal reference, fully discriminates the four most frequent posterior fossa tumors in children.

[Frontal giant cell glioblastoma: radio-induced tumor? Case report and literature review]

The current WHO classification recognizes two distinct variants of glioblastoma multiforme (GBMs): giant cell glioblastoma (GCG) and gliosarcoma, based on histological heterogeneity. Unlike conventional GBMs, GCGs preferentially occur in younger individuals and are associated with a better prognosis, a few reports documenting prolonged survival up to 17 years after diagnosis. However, transformation to gliosarcoma is possible and has been already reported. Radio-induced glioblastoma, which meets Cahan's criteria for radio-induced tumor, is very rare; the first case was published by Kleriga et al. We report a rare case observed in a 46-year-old man with a past history of right nose leiomyosarcoma treated 40 years earlier by surgery and interstitial and external beam radiation. At admission, the patient presented left hemiparesis revealing a right frontal GCG confirmed by pathology after cranial surgery. We describe this case firstly because of its rare histological variety and discuss its clinical, radiological, histopathological, therapeutic and prognostic characteristics with literature data. Secondly, because of its occurrence 40 years after external radiotherapy, which could suggest the hypothesis of radio-induced glioblastoma.

Transcriptional explorations of CAPN3 identify novel splicing mutations, a large-sized genomic deletion and evidence for messenger RNA decay

Mutations in the gene encoding calpain-3 (CAPN3) cause autosomal recessive limb-girdle muscular dystrophy type 2A (LGMD2A) and idiopathic eosinophilic myositis. Accurate diagnosis and genetic counselling are based on the identification of disease-causing mutations on both alleles of CAPN3 in the patients. In the present study, we used transcriptional analysis as a complementary approach for patients suspected of being affected with LGMD2A, in whom initial denaturing high-performance liquid chromatography genomic mutation screening evidenced no or only one CAPN3 mutation obviously considered as disease causing. This allowed to identify and characterize cDNA deletions. Further genomic analysis allowed to determine the origin of these deletions, either as splicing defects caused by intronic mutations or as an internal multi-exonic deletion. In particular, we report two novel CAPN3 mutations (c.1745 + 4_1745 + 7delAGTG in IVS13 and c.2185-16A>G in IVS20) and a recurrent large-sized genomic deletion including exons 2-8 for which genomic breakpoints have been characterized. In addition, our results indicate nonsense-mediated messenger RNA decay as a mechanism for under-expression of CAPN3 associated to some specific variations.

Neuroimaging of neonatal encephalopathies

Neonatal brain disorders consist of a wide chapter including brain malformations, hypoxic-ischemic encephalopathy (HIE), intracranial infections, perinatal trauma and metabolic encephalopathy. We will focus here on HIE, intracranial infections (especially materno-fetal infection with or without prolonged and/or premature rupture of membranes) and metabolic encephalopathy, those three conditions being the most frequent so far in our experience. Neonatal stroke is also analyzed. Moreover minor perinatal events might be superimposed on an already damaged (infective, edematous, metabolically abnormal or maldeveloped) brain, highlighting the main role and potential benefits of neuroimaging during the neonatal period. The different methods of brain imaging are thus reported with their advantages and disadvantages.

MR imaging of brain maturation

Magnetic resonance imaging (MRI) is the imaging tool of choice to evaluate brain maturation and especially brain myelination. Magnetic resonance imaging also provides functional insight through diffusion images and proton spectroscopy. In this review the MRI techniques are analyzed for both pre- and postnatal periods. The origin of MR signal changes is also detailed in order to understand normal myelination evolution and the consequences on brain maturation of the different pathologies encountered prior and after birth. Because MRI is "blind" in terms of signal on conventional sequences after 2 years of age, a particular attention is given to diffusion images and proton spectroscopy of the developing brain.

A novel mutation 3090 G>A of the mitochondrial 16S ribosomal RNA associated with myopathy

We describe a young woman who presented with a progressive myopathy since the age of 9. Spectrophotometric analysis of the respiratory chain in muscle tissue revealed combined and profound complex I, III, II+III, and IV deficiency ranging from 60% to 95% associated with morphological and histochemical abnormalities of the muscle. An exhaustive screening of mitochondrial transfer and ribosomal RNAs showed a novel G>A substitution at nucleotide position 3090 which was detected only in urine sediment and muscle of the patient and was not found in her mother's blood cells and urine sample. We suggest that this novel de novo mutation in the 16S ribosomal RNA, a nucleotide which is highly conserved in different species, would impair mitochondrial protein synthesis and would cause a severe myopathy.

Épendymomes intracrâniens de l'adulte. Diagnostic histologique et facteurs histopronostiques

BACKGROUND

Intracranial ependymomas are rare in adults and histopathological prognostic factors are poorly determined.

PURPOSE

A retrospective multicentric study was conducted in France in order to assess the prognostic value of histology.

MATERIAL

Between 1990 and 2004, 216 adult patients with newly diagnosed ependymomas were treated in 19 French centers. Eligibility required institutional histopathological confirmation of an ependymoma and available clinical history and MRI features (see comparison paper).

METHODS

Histological preparations and one paraffin embedded block from each patient were sent to Pr D. Figarella-Branger in Marseille. Central review by four neuropathologists (D. Figarella-Branger, A. Maues de Paula, C. Fernandez and A. Jouvet) was performed. Specimens for which all pathologists agreed with the histological diagnosis of ependymomas were included, whereas cases for which all disagree were excluded and reclassified. In the event of doubt and/or discrepancies between pathologists immunostaining was performed in order to reach a consensus diagnosis. Diagnostic of ependymomas was confirmed in 121 cases (56%). In theses cases, ependymomas were classified according to the WHO system (subtype and grade). The potential prognostic value (overall survival OS and disease free survival DFS) of the following histological parameters was examined: perivascular pseudorosettes, ependymal rosettes, hyalinized vessels, mitotic index, microvascular proliferation, necrosis, area of increased cellularity, nuclear atypia, brain invasion and Mib-1 labelling index.

RESULTS

Among the 121 ependymomas, 88 were grade II (47 classic, 17 cellular, 2 papillar, 6 clear cells and 16 tanicytic) and 33 grade III. WHO grading, occurrence of microvascular proliferation, necrosis, nuclear atypia and high proliferative index were correlated with both OS and DFS. Moreover, quantification of certain parameters enabled a reproducible grading system correlated with both OS and DFS.

Duane retraction syndrome: MRI features in two cases

PURPOSE

Neuroimaging findings in Duane's retraction syndrome (DRS), through magnetic resonance imaging (MRI), suggest that aplasia of the abducens nerve (VI) can be responsible for several forms of DRS.

METHODS

Brain MRI was performed in two children of 2.5 and 7 years of age with left sided DRS type II and right sided DRS type I, respectively. 3D T2 weighted images through the brainstem were acquired in order to visualize the cranial nerves especially the abducens (VI) and oculomotor (III) nerves.

RESULTS

The abducens nerve on the affected side could not be observed in these two different types of DRS with normal morphology of the third nerves.

CONCLUSION

Absence of the VI nerve has been described recently in DRS types I and III only, while DRS type II is usually associated with normal VI nerve on MRI. However our results show that aplasia of the VI nerve can also be seen in DRS type II resulting in new insight of the pathogenesis of this clinical entity.

Diffusion-weighted imaging in normal fetal brain maturation

Diffusion-weighted imaging (DWI) provides information about tissue maturation not seen on conventional magnetic resonance imaging. The aim of this study is to analyze the evolution over time of the apparent diffusion coefficient (ADC) of normal fetal brain in utero. DWI was performed on 78 fetuses, ranging from 23 to 37 gestational weeks (GW). All children showed at follow-up a normal neurological evaluation. ADC values were obtained in the deep white matter (DWM) of the centrum semiovale, the frontal, parietal, occipital and temporal lobe, in the cerebellar hemisphere, the brainstem, the basal ganglia (BG) and the thalamus. Mean ADC values in supratentorial DWM areas (1.68 +/- 0.05 mm(2)/s) were higher compared with the cerebellar hemisphere (1.25 +/- 0.06 mm(2)/s) and lowest in the pons (1.11 +/- 0.05 mm(2)/s). Thalamus and BG showed intermediate values (1.25 +/- 0.04 mm(2)/s). Brainstem, cerebellar hemisphere and thalamus showed a linear negative correlation with gestational age. Supratentorial areas revealed an increase in ADC values, followed by a decrease after the 30th GW. This study provides a normative data set that allows insights in the normal fetal brain maturation in utero, which has not yet been observed in previous studies on premature babies.

Lethal paradoxical cerebral vein thrombosis due to suspicious anticoagulant rodenticide intoxication with chlorophacinone

Superwarfarin exposure is a growing health problem, described in many countries. The authors report a case of suspicious chlorophacinone poisoning with a problematic diagnosis. They review the literature and discuss particularities of anticoagulant rodenticide intoxication, as well as the apparent contradiction between anticoagulant intoxication and lethal thrombosis.

Infratentorial pediatric brain tumors: the value of new imaging modalities

The correct assessment of the four most frequent infratentorial brain tumors in children (medulloblastoma, ependymoma, pilocytic astrocytoma and infiltrating glioma) has always been problematic. They are known to often resemble one another on conventional magnetic resonance (MR) imaging. We tested the hypothesis whether the combined strength of diffusion-weighted imaging (DWI) and proton MR spectroscopy (MRS) could help differentiate these tumors. Seventeen children with untreated posterior fossa tumors were investigated between January 2005 and January 2006 with conventional MR imaging and combined DWI and MR spectroscopy using a single-voxel technique at short and long echo time (TE) of 30 ms and 135 ms respectively. Apparent diffusion coefficient (ADC) values were retrieved after regions of interest were manually positioned within non necrotic tumor core. Water signal was quantified and metabolite signals were compared and analyzed using linear discriminant analysis. When a combination of ADC values and normalized metabolites was used, all tumors could be discriminated against one other. This could only be achieved when metabolites were normalized using water as an internal standard. They could not be discriminated when using metabolite ratios or ADC values alone, nor could they be differentiated using creatine (Cr) as an internal reference even in combination with ADC values. In conclusion, linear discriminant analysis and multiparametric combination of DWI and MRS, although not replacing histology, fully discriminates the four most frequent posterior fossa tumors in children, but metabolites have to be normalized using water and not Cr signal as an internal reference.

Les oligodendrogliomes supra-tentoriels : imagerie métabolique

Metabolic imaging with positron emission tomography (PET) provides, in neuro-oncology, information complementary to that provided by anatomic imaging obtained with CT-scanner or MRI. Only a few publications have yet reported its use in oligodendroglial tumors. These findings and partial results obtained in ongoing work, suggest some preliminary conclusions: 11C-MET (L-methyl-methionine) is a more appropriate tracer than 18F-FDG (fluoro-deoxy-glucose), in terms of both specificity and sensitivity, for the assessment of patients with this category of tumor. PET/MET allows differentiation between grade II and grade III oligodendrogliomas; better targeting for stereotactic biopsy; more accurate assessment of the post-operative residual tumor; identification of progression from low-grade to anaplastic grade during the disease course; differentiation between recurrence and a post-radiation processes. PET/MET allows, to some extent, prediction of response to radiotherapy; and, probably, to chemotherapy.

Screening of TP53 mutations by DHPLC and sequencing in brain tumours from patients with an occupational exposure to pesticides or organic solvents

The aetiology of brain tumours remains unclear. Occupational exposures to pesticides and organic solvents are suspected risk factors. The case-control study CEREPHY (221 cases, 442 controls) carried in the Departement de la Gironde in France revealed a significantly increased risk of brain tumours for subjects most exposed to pesticides. In some cancers, TP53 mutations could reflect exposure to specific carcinogens. These mutations are present in approximately 30% of astrocytic brain tumours. In a pilot study, we explored the hypothesis that pesticide or solvent exposure could raise the frequency of TP53 mutations in brain tumour cells. We investigated TP53 mutations in exons 2-11 by denaturing high performance liquid chromatography (DHPLC) and sequencing, and p53 accumulation by immunohistochemistry in brain tumour of the 30 patients from CEREPHY study with a history of occupational exposure to pesticides (n = 21) and/or organic solvents (n = 14) for whom tumoral tissue was available. Included cases concerned 27% of CEREPHY cases exposed to pesticides and, based on the cumulative index of occupational exposure, they were more exposed to pesticides. There were 12 gliomas, 6 meningiomas, 7 neurinomas, 2 central nervous system lymphomas and 3 tumours of other histological types. We detected TP53 mutations in three tumours, which is similar to the expected number (3.3) calculated from 46 published studies referenced in the IARC TP53 mutations database, taking into account histological types. Considering TP53 mutations previously detected in the laboratory by DHPLC and the frequency of TP53 polymorphisms detected in this sample (similar to published data), the TP53 mutations rate is probably not underestimated. These preliminary results, even if it was on a limited number of tumours, are not in favour of the role of pesticide or organic solvent exposure in the occurrence of TP53 mutations in brain tumours.

[Stent-graft treatment of a ruptured aortic graft: a case report]

The authors report the clinical and imaging features of a patient with rupture of an aortoiliac graft successfully treated by endovascular approach. The endovascular treatment is easy to perform and effective. The main pitfall of this technique is the limited availability of stent-grafts.

[A case of nasal septum schwannoma: endoscopic resection]

OBJECTIVES

To define clinical and radiological characteristics of nasal septal schwannoma, and to propose endoscopic surgery.

PATIENT AND METHODS

We report a case of an isolated schwannoma of the anterior part of the nasal septum, without involvement of any local structure. The only preoperative symptom was nasal obstruction. Imaging study included a CT scan and an MRI study.

RESULTS

Schwannoma is a sheath tumor originating from Schwann cells of peripheral nerves. It rarely occurs in nasal and paranasal sinuses and its development on the nasal septum is extremely rare. Complete removal of the tumor was performed by endoscopic sinus surgery technique. Limits of the excision were free of tumor and the histological type was Antoni type A Schwannoma. After a year of follow up, the patient is free of recurrence.

CONCLUSION

The Schwannoma of the nasal septum is a rare tumour whose clinical and radiological diagnosis by CT scan and IRM is relatively easy. Its treatment is surgical and the endoscopic surgery can be proposed in the forms slightly extensive.

CDKN2A , CDKN2B and p14 ARF are frequently and differentially methylated in ependymal tumours

Ependymal tumours are histologically and clinically varied lesions. Numerical abnormalities of chromosome 9 are frequently associated with these tumours. Nevertheless, the three important tumour suppressor genes located in this chromosome, CDKN2A, CDKN2B and p14 ARF, have not been reported to be commonly altered in them. We studied promoter methylation of these genes, an important mechanism associated with gene silencing in a series of 152 ependymal tumours of WHO grades I to III. Methylation status of the CDKN2A, CDKN2B and p14 ARF promoters was assessed by methylation-specific polymerase chain reaction and the genetic results were correlated to clinicopathological features. We observed promoter methylation for CDKN2A in 21% (26/123) of tumours, for CDKN2B in 32% (23/71) and p14 ARF in 21% (23/108). For all three genes, posterior fossa ependymomas were less frequently methylated in paediatric patients than in adults. For CDKN2B, extracranial tumours were more frequently methylated than intracranial ones. For CDKN2B and p14 ARF, methylation was more frequent in low-grade tumours; the reverse was observed for CDKN2A. CDKN2A, CDKN2B and p14 ARF promoters were methylated in 21-32% of the tumours. Frequencies of methylation varied according to clinicopathological features. This suggests a role for these genes in ependymoma tumorigenesis.

[Sphenoid sinusitis]

Sphenoid sinusitis is uncommon, with an incidence of about 2.7%. Failure to diagnose and treat sphenoid sinus disease has been shown to lead to serious neurologic sequellae. Plain radiographs play a limited role in the management of sinusitis. CT scan can provide a positive diagnosis by the visualization of mucosal thickening, air-fluid level and complete opacification of the sinusal cavities. In addition, CT can provide more information about the anatomy and abnormalities of the sphenoid sinus. MRI is used in cases of suspected tumors or neurologic involvement. The most common presenting symptom is headache that arise characteristically, but rarely, from the vertex. Sphenoiditis has a high risk of severe neurologic involvement, cavernous sinus thrombosis being one of the most serious complications.