Bilateral cavitations of ganglionic eminence: a fetal MR imaging sign of halted brain development.

SUMMARY: Ganglionic eminence is the main transitory proliferative structure of the ventral telencephalon in human fetal brain and it contributes for at least 35% to the population of cortical interneurons; however data on the human GE anomalies are scarce. We report 5 fetal MR imaging observations with bilateral symmetric cavitations in their GE regions resembling an inverted open C shape and separating the GE itself form the deeper parenchyma. Imaging, neuropathology, and follow-up features suggested a malformative origin. All cases had in common characteristics of lissencephaly with agenesis or severe hypoplasia of corpus callosum of probable different genetic basis. From our preliminary observation, it seems that GE cavitations are part of conditions which are also accompanied by severe cerebral structure derangement.

Anti-cyclic citrullinated peptide antibodies in systemic lupus erythematosus patients with articular involvement: a predictive marker for erosive disease?

A small number of systemic lupus erythematosus (SLE) patients develop an erosive disease. Some studies have suggested an association between anti-cyclic citrullinated (anti-CCP) antibodies and this pattern of arthritis, but their exact significance in SLE patients remains unclear. The aim of this study was to evaluate the prevalence of anti-CCP antibodies in SLE patients with different subsets of articular disease. Among 521 SLE patients followed in this center from 1976 to 2011, those with articular involvement (n=298) were selected to take part in the study. We searched for anti-CCP2 IgG antibodies in 198 patients using a commercial enzyme linked immunosorbent assay (Immunoscan RA, Eurodiagnostica). In 174 patients the results for rheumatoid factor (RF) by nephelometry were retrospectively collected. C reactive protein (CRP) was obtained from clinical records. Patients were classified into 3 groups: erosive, non-erosive deforming, non-erosive non-deforming arthritis. Results of the different tests were compared among the groups. P<0.05 was considered statistically significant. Anti-CCP antibodies were significantly associated with erosive disease. We also found that RF positivity and increased CRP were more frequent in erosive arthritis and erosive or non-deforming arthritis, respectively, than in non-erosive non-deforming arthritis. This study supports the evidence that anti-CCP antibodies could be a useful marker of erosive disease in SLE patients. Increase in RF and CRP could be an additional means of identifying lupus patients with arthritis at risk of a worse prognosis.

In vivo detection of cortical abnormalities in BCNU-treated rats, model of cortical dysplasia, using manganese-enhanced magnetic resonance imaging.

The 1-3-bis-chloroethyl-nitrosurea (BCNU)-treated rats represent a good model of cortical dysplasia (CD), as proved by the presence of some histological alterations similar to those observed in human CD, including cortical thinning, laminar disorganization, and heterotopia. The cortical cytoarchitectonics of BCNU-treated rats has been widely investigated by means of histological procedures, immunocytochemistry, and in situ hybridization techniques, implying the sacrifice of the animals. With the aim of identifying brain alterations in vivo to have the possibility of performing longitudinal studies, we used both conventional T(2)-weighted magnetic resonance imaging (MRI) and manganese-enhanced MRI (MEMRI). Though the T(2)-weighted MRI showed the gross anatomical landmarks of BCNU-treated rats, only following Mn(2+) administration T(1)-weighted MRI did reveal the brain cytoarchitectonics both of control and BCNU-treated rats. In particular, changes in MEMRI signal depicted the laminar architecture of control rats while BCNU-treated cortex showed no appreciable changes in MEMRI contrast, consistent with their abnormal cortical lamination. Furthermore, in the treated animals MEMRI revealed hyperintense signals corresponding to heterotopia, as shown by the comparison between MEMRI images and Thionin staining and calbindin immunocytochemistry from the same animals. The qualitative findings obtained with MEMRI were semi-quantitatively confirmed by image segmentation of grey matter. Overall, these data show that MEMRI can be used as a non-invasive technique to investigate cortical alterations in animal models of CD in vivo, giving the possibility to perform longitudinal studies, such as electrophysiological recordings or behavioural investigations.

Development of cortical malformations in BCNU-treated rat, model of cortical dysplasia.

Cortical dysplasia (CD) comprises a wide range of cerebral cortex alterations ranging from severe brain malformations to local disruption of the cortical structure. Most hypotheses focused on the role of embryonic/perinatal development insults as the main cause for the majority of CD. Rats with prenatal exposure to BCNU (1-3-bis-chloroethyl-nitrosurea) represent an injury-based model and reproduce many anatomical features seen in human patients with CD, such as altered cortical layering and the presence of heterotopia and dysmorphic/heterotopic neurons. With the aim to investigate the formation and evolution of CD during development, we analysed the expression of a panel of layer-specific genes (Nurr1, Er81, Ror-ß and Cux2, markers of layers VI, V, IV and superficial layers, respectively) in BCNU-treated cortices from E17 to postnatal day 14. By means of appropriate immunohistochemical markers, we also analysed the structural organization of embryonic ventricular zone and of glial and axonal fibres, substrates supporting radial and tangential migration, respectively. The main results of the present study are: (i) the ventricular zone appeared disorganized and the neuroependyma was partially disrupted; (ii) radial glia scaffold and tangential fibres were deeply disarranged, thus explaining the neuronal migration defects; (iii) cortical heterotopia were detectable by E19, whereas periventricular heterotopia were detectable after birth; (iv) both cortical and periventricular heterotopia showed a pseudo-laminar structure, with cells of the upper cortical layers in the core of the nodules and cells of layer IV and V at their border; (v) the distribution of GABAergic cells was altered since the embryonic stages, as a consequence of the derangement of tangential fibres. Our analysis sheds light on how a malformed cortex develops after a temporally discrete environmental insult and adds additional knowledge on specific aspects of the etiopathogenesis of CD.

Joubert syndrome with bilateral polymicrogyria: clinical and neuropathological findings in two brothers.

Joubert syndrome (JS) is characterized by hypotonia, ataxia, developmental delay, and a typical neuroimaging finding, the so-called "molar tooth sign" (MTS). The association of MTS and polymicrogyria (PMG) has been reported as a distinct JS-related disorder (JSRD). So far, five patients have been reported with this phenotype, only two of them being siblings. We report on one additional family, describing a living child with JS and PMG, and the corresponding neuropathological picture in the aborted brother. No mutations were detected in the AHI1 gene, the only so far associated with the JS + PMG phenotype. Moreover, linkage analysis allowed excluding all known gene loci, suggesting further genetic heterogeneity.

Expression of layer-specific markers in the adult neocortex of BCNU-Treated rat, a model of cortical dysplasia.

The experimental model of cortical dysplasia (CD) obtained by administering carmustine (1-3-bis-chloroethyl-nitrosurea [BCNU]) in pregnant rat uterus mimics the histopathological abnormalities observed in human CD patients: altered cortical layering, and presence of heterotopia and dysmorphic/heterotopic neurons. To investigate further the cortical layering disruption and the neuronal composition of heterotopia in BCNU-exposed cortex, we analyzed the expression pattern of the transcription factors Nurr1, Er81, Ror-beta, and Cux2 (respectively specific markers of layers VI, V, IV and superficial layers) in the cortical areas of BCNU-treated rats by means of in situ hybridization, and compared the findings with those observed in adult control rats. Combining in situ hybridization and immunohistochemistry we also investigated the origin of dysmorphic or heterotopic neurons. The main results of the present study are (i) the analysis of cortical layer thickness revealed that the cortical thinning in the BCNU model was prevalently restricted to the superficial layers; (ii) in cortical and periventricular heterotopia, the prevalent presence of superficial layer neurons in the internal areas, and deeper layer neurons in a more peripheral region, demonstrated a rudimentary pattern of laminar organization in nodule formation; and (iii) the Er81 signal in the dysmorphic and heterotopic pyramidal neurons located in layers I/II showed that they belong to layer V. These results shed light on the disorganization of the laminar architecture of the BCNU model by providing correlations with normal cortical layering and revealing the ontogenesis of heterotopia and heterotopic/dysmorphic neurons. They also provide strong evidence of the usefulness of layer-specific markers in investigating the neuropathology of CD, thus opening up the possibility of expanding their application to human neuropathology.

GABA immunoreactivity in the developing rat thalamus and Otx2 homeoprotein expression in migrating neurons.

We investigated the expression of gamma-aminobutyric acid (GABA) in the developing rat thalamus by immunohistochemistry, using light, confocal and electron microscopy. We also examined the relationship between the expression of the homeoprotein Otx2, a transcription factor implicated in brain regionalization, and the radial and non-radial migration of early generated thalamic neurons, identified by the neuronal markers calretinin (CR) and GABA. The earliest thalamic neurons generated between embryonic days (E) 13 and 15 include those of the reticular nucleus, entirely composed by GABAergic neurons. GABA immunoreactivity appeared at E14 in immature neurons and processes laterally to the neuroepithelium of the diencephalic vesicle. The embryonic and perinatal periods were characterized by the presence of abundant GABA-immunoreactive fibers, mostly tangentially oriented, and of growth cones. At E15 and E16, GABA was expressed in radially and non-radially oriented neurons in the region of the reticular thalamic migration, between the dorsal and ventral thalamic primordia, and within the dorsal thalamus. At these embryonic stages, some CR- and GABA-immunoreactive migrating-like neurons, located in the migratory stream and in the dorsal thalamus, expressed the homeoprotein Otx2. In the perinatal period, the preponderance of GABAergic neurons was restricted to the reticular nucleus and several GABAergic fibers were still detectable throughout the thalamus. The immunolabeling of fibers progressively decreased and was no longer visible by postnatal day 10, when the adult configuration of GABA immunostaining was achieved. These results reveal the spatio-temporal features of GABA expression in the developing thalamus and suggest a novel role of Otx2 in thalamic cell migration.

Analysis of SNAP-25 immunoreactivity in hippocampal inhibitory neurons during development in culture and in situ.

Synaptosomal associated protein of 25 kDa (SNAP-25) is a component of the soluble N-ethylmaleimide-sensitive fusion protein (NSF) attachment protein receptor (SNARE) complex which plays a central role in synaptic vesicle exocytosis. We have previously demonstrated that adult rat hippocampal GABAergic synapses, both in culture and in brain, are virtually devoid of SNAP-25 immunoreactivity and are less sensitive to the action of botulinum toxin type A, which cleaves this SNARE protein [Neuron 41 (2004) 599]. In the present study, we extend our findings to the adult mouse hippocampus and we also provide demonstration that hippocampal inhibitory synapses lacking SNAP-25 labeling belong to parvalbumin-, calretinin- and cholecystokinin-positive interneurons. A partial colocalization between SNAP-25 and glutamic acid decarboxylase is instead detectable in developing mouse hippocampus at P0 and, at a lesser extent, at P5. In rat embryonic hippocampal cultures at early developmental stages, SNAP-25 immunoreactivity is detectable in a percentage of GABAergic neurons, which progressively reduces with time in culture. Consistent with the presence of the substrate, botulinum toxin type A is partially effective in inhibiting synaptic vesicle recycling in immature GABAergic neurons. Since SNAP-25, beside its role as a SNARE protein, is involved in additional processes, such as neurite outgrowth and regulation of calcium dynamics, the presence of higher levels of the protein at specific stages of neuronal differentiation may have implications for the construction and for the functional properties of brain circuits.