MRI and pathology correlations in the medulla in sudden unexpected death in epilepsy (SUDEP): a postmortem study

AIMS

Sudden unexpected death in epilepsy (SUDEP) likely arises as a result of autonomic dysfunction around the time of a seizure. In vivo MRI studies report volume reduction in the medulla and other brainstem autonomic regions. Our aim, in a pathology series, is to correlate regional quantitative features on 9.4T MRI with pathology measures in medullary regions.

METHODS

Forty-seven medullae from 18 SUDEP, 18 nonepilepsy controls and 11 epilepsy controls were studied. In 16 cases, representing all three groups, ex vivo 9.4T MRI of the brainstem was carried out. Five regions of interest (ROI) were delineated, including the reticular formation zone (RtZ), and actual and relative volumes (RV), as well as T1, T2, T2* and magnetization transfer ratio (MTR) measurements were evaluated on MRI. On serial sections, actual and RV estimates using Cavalieri stereological method and immunolabelling indices for myelin basic protein, synaptophysin and Microtubule associated protein 2 (MAP2) were carried out in similar ROI.

RESULTS

Lower relative RtZ volumes in the rostral medulla but higher actual volumes in the caudal medulla were observed in SUDEP (P < 0.05). No differences between groups for T1, T2, T2* and MTR values in any region was seen but a positive correlation between T1 values and MAP2 labelling index in RtZ (P < 0.05). Significantly lower MAP2 LI were noted in the rostral medulla RtZ in epilepsy cases (P < 0.05).

CONCLUSIONS

Rostro-caudal alterations of medullary volume in SUDEP localize with regions containing respiratory regulatory nuclei. They may represent seizure-related alterations, relevant to the pathophysiology of SUDEP.

Spatiotemporal dynamics of PDGFRβ expression in pericytes and glial scar formation in penetrating brain injuries in adults

Aims

Understanding the spatiotemporal dynamics of reactive cell types following brain injury is important for future therapeutic interventions. We have previously used penetrating cortical injuries following intracranial recordings as a brain repair model to study scar‐forming nestin‐expressing cells. We now explore the relationship between nestin‐expressing cells, PDGFRβ⁺ pericytes and Olig2⁺ glia, including their proliferation and functional maturation.

Methods

In 32 cases, ranging from 3 to 461 days post injury (dpi), immunohistochemistry for PDGFRβ, nestin, GFAP, Olig2, MCM2, Aquaporin 4 (Aq4), Glutamine Synthetase (GS) and Connexin 43 (Cx43) was quantified for cell densities, labelling index (LI) and cellular co‐expression at the injury site compared to control regions.

Results

PDGFRβ labelling highlighted both pericytes and multipolar parenchymal cells. PDGFRβ LI and PDGFRβ⁺/MCM2⁺ cells significantly increased in injury Zones at 10–13 dpi with migration of pericytes away from vessels with increased co‐localization of PDGRFβ with nestin compared to control regions (P < 0.005). Olig2⁺/MCM2⁺ cell populations peaked at 13 dpi with significantly higher cell densities at injury sites than in control regions (P < 0.01) and decreasing with dpi (P < 0.05). Cx43 LI was reduced in acute injuries but increased with dpi (P < 0.05) showing significant cellular co‐localization with nestin and GFAP (P < 0.005 and P < 0.0001) but not PDGFRβ.

Conclusions

These findings indicate that PDGFRβ⁺ and Olig2⁺ cells contribute to the proliferative fraction following penetrating brain injuries, with evidence of pericyte migration. Dynamic changes in Cx43 in glial cell types with dpi suggest functional alterations during temporal stages of brain repair.

Review: The past, present and future challenges in epilepsy-related and sudden deaths and biobanking

Awareness and research on epilepsy-related deaths (ERD), in particular Sudden Unexpected Death in Epilepsy (SUDEP), have exponentially increased over the last two decades. Most publications have focused on guidelines that inform clinicians dealing with these deaths, educating patients, potential risk factors and mechanisms. There is a relative paucity of information available for pathologists who conduct these autopsies regarding appropriate post mortem practice and investigations. As we move from recognizing SUDEP as the most common form of ERD toward in-depth investigations into its causes and prevention, health professionals involved with these autopsies and post mortem procedure must remain fully informed. Systematizing a more comprehensive and consistent practice of examining these cases will facilitate (i) more precise determination of cause of death, (ii) identification of SUDEP for improved epidemiological surveillance (the first step for an intervention study), and (iii) biobanking and cell-based research. This article reviews how pathologists and healthcare professionals have approached ERD, current practices, logistical problems and areas to improve and harmonize. The main neuropathology, cardiac and genetic findings in SUDEP are outlined, providing a framework for best practices, integration of clinical, pathological and molecular genetic investigations in SUDEP, and ultimately prevention.

Review: Challenges in the histopathological classification of ganglioglioma and DNT: microscopic agreement studies and a preliminary genotype-phenotype analysis

Low-grade epilepsy-associated brain tumours (LEAT) are the second most common cause for drug-resistant, focal epilepsy, that is ganglioglioma (GG) and dysembryoplastic neuroepithelial tumours (DNT). However, molecular pathogenesis, risk factors for malignant progression and their frequent association with drug-resistant focal seizures remain poorly understood. This contrasts recent progress in understanding the molecular-genetic basis and targeted treatment options in diffuse gliomas. The Neuropathology Task Force of the International League Against Epilepsy examined available literature to identify common obstacles in diagnosis and research of LEAT. Analysis of 10 published tumour series from epilepsy surgery pointed to poor inter-rater agreement for the histopathology diagnosis. The Task Force tested this hypothesis using a web-based microscopy agreement study. In a series of 30 LEAT, 25 raters from 18 countries agreed in only 40% of cases. Highest discordance in microscopic diagnosis occurred between GG and DNT variants, when oligodendroglial-like cell patterns prevail, or ganglion cells were difficult to discriminate from pre-existing neurons. Suggesting new terminology or major histopathological criteria did not satisfactorily increase the yield of histopathology agreement in four consecutive trials. To this end, the Task Force applied the WHO 2016 strategy of integrating phenotype analysis with molecular-genetic data obtained from panel sequencing and 450k methylation arrays. This strategy was helpful to distinguish DNT from GG variants in all cases. The Task Force recommends, therefore, to further develop diagnostic panels for the integration of phenotype-genotype analysis in order to reliably classify the spectrum of LEAT, carefully characterize clinically meaningful entities and make better use of published literature.

The effect of different regimens of oestrogens on the clotting and fibrinolytic system of the post-menopausal woman

The effects of six different regimens of hormone replacement therapy on coagulation, fibrinolysis and platelet aggregation were sudied in 33 symptomatic, post-menopausal women. Studies were performed before and after 3 months of therapy in the six treatment groups, Premarin, Progynova, Harmogen, Serial 28, ethynodiol diacetate and a testosterone and oestradiol implant. No changes in any parameter were detected following administration of Premarin, Progynova or an implant of testosterone and oestradiol. Serial 28 produced a significant increase in plasminogen concentration and increased the extent of platelet aggregation in 0.5 micron adrenalin solution. Harmogen produced an increase in the extent of platelet aggregation in 1.0 micron adrenalin solution, but a decrease in the rate of platelet aggregation in 1.0 micron solution. Ethynodiol diacetate caused a significant decrease in the kaolin-cephalin clotting time but decreased the extent of platelet aggregation in 0.5 and 1.0 micron solutions of adrenalin. FDPs developed following therapy in 9 of the 33 patients. These were evenly distributed between the groups. No patients had any change in anti-Xa concentration, platelet count or platelet aggregation in thrombin.

Interictal psychosis following temporal lobe surgery: dentate gyrus pathology

BACKGROUND

De novo interictal psychosis, albeit uncommon, can develop in patients following temporal lobe surgery for epilepsy. Pathological alterations of the dentate gyrus, including cytoarchitectural changes, immaturity and axonal reorganization that occur in epilepsy, may also underpin co-morbid psychiatric disorders. Our aim was to study candidate pathways that may be associated with the development of interictal psychosis post-operatively in patients with hippocampal sclerosis (HS).

METHOD

A total of 11 patients with HS who developed interictal psychosis (HS-P) post-operatively were compared with a matched surgical HS group without psychosis (HS-NP). Resected tissues were investigated for the extent of granule cell dispersion, mossy fibre sprouting and calbindin expression in the granule cells. We quantified doublecortin, mini-chromosome maintenance protein 2 (MCM2) and reelin-expressing neuronal populations in the dentate gyrus as well as the distribution of cannabinoid type 1 receptor (CBR1).

RESULTS

The patterns of neuronal loss and gliosis were similar in both groups. HS-P patients demonstrated less mossy fibre sprouting and granule cell dispersion (p < 0.01) and more frequent reduction in calbindin expression in granule cells. There were no group differences in the densities of immature MCM2, doublecortin and reelin-positive cells. CBR1 labelling was significantly lower in Cornu ammonis area CA4 relative to other subfields (p < 0.01); although reduced staining in all hippocampal regions was noted in HS-P compared with HS-NP patients, the differences were not statistically significant.

CONCLUSIONS

The alterations in dentate gyrus pathology found in HS-P patients could indicate underlying differences in the cellular response to seizures. These mechanisms may predispose to the development of psychosis in epilepsy and warrant further investigation.

A comparative study of the dentate gyrus in hippocampal sclerosis in epilepsy and dementia

Aims:

Hippocampal sclerosis (HS) is long-recognized in association with epilepsy (HS_E) and more recently in the context of cognitive decline or dementia in the elderly (HS_D), in some cases as a component of neurodegenerative diseases, including Alzheimer's disease (AD) and fronto-temporal lobe dementia (FTLD). There is an increased risk of seizures in AD and spontaneous epileptiform discharges in the dentate gyrus of transgenic AD models; epilepsy can be associated with an age-accelerated increase in AD-type pathology and cognitive decline. The convergence between these disease processes could be related to hippocampal pathology. HS_E typically shows re-organization of both excitatory and inhibitory neuronal networks in the dentate gyrus, and is considered to be relevant to hippocampal excitability. We sought to compare the pathology of HS_E and HS_D, focusing on re-organization in the dentate gyrus. Methods: In nine post mortem cases with HS_E and bilateral damage, 18 HS_D and 11 controls we carried out immunostaining for mossy fibres (dynorphin), and interneuronal networks (NPY, calbindin and calretinin) on sections from the mid-hippocampal body. Fibre sprouting (FS) or loss of expression in the dentate gyrus was semi-quantitatively graded from grade 0 (normal) to grade 3 (marked alteration). Results: Significantly more re-organization was seen with all four markers in the HS_E than HS_D group (P < 0.01). Mild alterations were noted in HS_D group with dynorphin (FS in 3 cases), calretinin (FS in 6 cases), NPY (FS in 11 cases) and calbindin (loss in 10 cases). In eight HS_D cases, alteration was seen with more than one antibody but in no cases were the highest grades seen. We also noted NPY and, to a lesser extent, calretinin labelling of Hirano bodies in CA1 of AD cases and some older controls, but not in HS_E. Conclusion: Reorganization of excitatory and inhibitory networks in the dentate gyrus is more typical of HS_E. Subtle alterations in HS_D may be a result of increased hippocampal excitability, including unrecognized seizure activity. An unexpected finding was the identification of NPY-positive Hirano bodies in HS_D but not HS_E, which may be a consequence of the relative vulnerabilities of interneurons in these conditions.

Changes in cortical thickness in the frontal lobes in schizophrenia are a result of thinning of pyramidal cell layers

Decreased cortical thickness and reduced activity as measured by fMRI in the grey matter of the subgenual cingulate cortex have been reported in schizophrenia and bipolar disorder, and cortical grey matter loss has been reliably reported in the frontal and temporal lobes in schizophrenia. The aim of this study was to examine the thickness of each of the six cortical layers in the subgenual cingulate cortex, five frontal lobe and four temporal lobe gyri. We examined two separate cohorts. Cohort 1 examines the subgenual cingulate cortex (SCC) in schizophrenia (n = 10), bipolar disorder (n = 15) and major depressive disorder (n = 20) against control subjects (n = 19). Cohort two examines frontal and temporal gyri in schizophrenia (n = 16), major depressive disorder (n = 6) against matched controls (n = 32). The cohorts were selected with identical clinical criteria, but underwent different tissue processing to contrast the effect of chemical treatment on tissue shrinkage. Measurements of layer I-VI thickness were taken from cresyl-violet- and haematoxylin-stained sections in cohort one and from cresyl-violet- and H&E-stained sections in cohort two. SCC cortical thickness decreased in male subjects with bipolar disorder (p = 0.048), and male schizophrenia cases showed a specific decrease in the absolute thickness of layer V (p = 0.003). Compared to controls, the relative thickness of layer V in the crown of the SCC decreased in schizophrenia (p < 0.001). A significant decrease in total cortical thickness was observed across the frontal lobe in schizophrenia (p < 0.0001), with specific pyramidal layer thinning in layers III (p = 0.0001) and V (p = 0.005). There was no effect of lateralization. No changes were noted in temporal lobe cortical thickness. This study demonstrates diminished pyramidal layer thickness resulting in decreased frontal lobe thickness in schizophrenia.

Group translocation as a mechanism for sucrose transfer into vacuoles from sugarcane cells

Isolated vacuoles from sugarcane cells took up uridine diphosphate glucose (UDP-Glc) from the surrounding medium at a rapid rate. After a 7-min incubation of vacuoles with UDP-[14C]Glc, sucrose and sucrose phosphate were identified in the vacuole extract. UDP-Glc in the incubation medium was converted to hexose phosphates, sucrose, and glucose, with very little UDP-Glc remaining. Fructose 6-phosphate was not required for UDP-Glc uptake nor was [(14)C]fructose 6-phosphate taken up even in the presence of UDP-Glc. Glucose 6-phosphate and glucose 1-phosphate also were not taken up into vacuoles. UDP-Glc uptake showed saturation kinetics with a K(m) of 0.7 mM and a V(max) of 11.1 nmol/min per 10(6) vacuoles. The optimum pH for UDP-Glc uptake was between 6.5 and 7.0. Uptake of UDP-Glc could be inhibited by p-chloromercuriphenylsulfonic acid, UDP, and GDP, and to a lesser extent by carbonyl cyanide m-chlorophenylhydrazone. The UDP-Glc binding site was specific for UDP-Glc; adenosine diphosphate glucose was not taken up, and guanosine diphosphate glucose did not compete with UDP-Glc for the binding site. The results suggest that sucrose transfer into vacuoles from sugarcane is via a group translocation mechanism, probably involving five tonoplast-bound enzymes.

Production and characterization of two monoclonal antibodies to bovine tumour necrosis factor alpha (TNF-alpha) and their cross-reactivity with ovine TNF-alpha

Tumour necrosis factor alpha (TNF-alpha) is an innate pro-inflammatory cytokine involved in protection against intracellular pathogens. Existing methods for measuring TNF-alpha production and function in ruminants are limited to ELISA and many rely on polyclonal antisera. With a view to developing improved detection methods for bovine (bov) TNF-alpha, monoclonal antibodies (mAb) were produced by immunising mice with a plasmid encoding bov TNF-alpha. Two of the resulting mAb, termed CC327 and CC328, were used to develop a sandwich ELISA capable of detecting both native and recombinant bov TNF-alpha. This ELISA did not detect recombinant ovine (ov) TNF-alpha. A luminometric method was applied to the ELISA to improve sensitivity for detection of native bov TNF-alpha in culture supernatants derived from bovine monocyte-derived dendritic cells (DC) infected with Mycobacterium bovis. Both CC327 and CC328 detected intracytoplasmic expression of TNF-alpha in mitogen-activated bovine T lymphocytes. However, only CC328 detected intracytoplasmic ovine TNF-alpha in transfected cells, explaining the failure of the sandwich ELISA to detect recombinant ov TNF-alpha. These mAbs have generated the capability to study the role of TNF-alpha in host immune protection and disease pathogenesis in ruminants.

Expression patterns of glial fibrillary acidic protein (GFAP)-delta in epilepsy-associated lesional pathologies

AIMS

Glial fibrillary acidic protein (GFAP)-delta is a novel isoform that differs in its C-terminal sequence from other GFAP isoforms. Previous studies suggest restriction of expression to the subpial layer, subventricular zone and the subgranular zone astrocytes, with an absence in pathological conditions causing reactive gliosis. GFAP-delta is speculated to have roles in regulation of astrocyte size and motility and a subpopulation of GFAP-delta-positive glia may be multipotent stem cells. The aim of this study was to investigate its expression in common causes of lesion-related refractory epilepsy.

METHODS

Hippocampal sclerosis (HS), focal cortical dysplasia (FCD) type IIB, cortical tuberous sclerosis (TSC) lesions, gangliogliomas, grey matter heterotopias and hemimegalencephaly from a wide age range of patients using both surgical and post mortem tissue specimens were studied.

RESULTS

GFAP-delta expression was observed in CA4 and CA1 astrocytes in HS with less frequent labelling in the granule cell layer, even where granule cell dispersion was present. No significant labelling was noted in the subiculum in HS cases or in any subfields in non-HS epilepsy cases. Balloon cells in FCDIIB and hemimegalencephaly, giant cells in TSC and the astrocytic component of gangliogliomas showed immunoreactivity, colocalizing with conventional GFAP. No neuronal expression for GFAP-delta was seen in any of the pathologies. Quantitative analysis in 10 FCDIIB and five TSC cases revealed greater numbers of GFAP-delta-positive balloon cells than conventional GFAP. There was no GFAP-delta expression within nodular heterotopia.

CONCLUSIONS

GFAP-delta expression patterns in HS overall appears to mirror regional reactive gliosis. It is a useful marker for the demonstration of balloon cells in FCD and TSC, which may be relevant to their abnormal size and localization. The lack of GFAP-delta within heterotopia supports their composition from cells destined for deeper cortical layers.

Bilateral reorganization of the dentate gyrus in hippocampal sclerosis: a postmortem study

BACKGROUND

Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry.

METHODS

Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21-96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death.

RESULTS

Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients.

CONCLUSION

Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon.

Balloon cells associated with granule cell dispersion in the dentate gyrus in hippocampal sclerosis

Granule cell dispersion (GCD) is a common finding in hippocampal sclerosis in patients with intractable focal epilepsy. It is considered to be an acquired, post-developmental rather than a pre-existing abnormality, involving dispersion of either mature or newborn neurones, but the precise factors regulating it and its relationship to seizures are unknown. We present two cases of GCD with associated CD34-immunopositive balloon cells, a cell phenotype associated with focal cortical dysplasia type IIB, considered to be a developmental cortical lesion promoting epilepsy. This observation opens up the debate regarding the origin of balloon cells and CD34 expression and their temporal relationship to seizures.

Correlation of quantitative MRI and neuropathology in epilepsy surgical resection specimens--T2 correlates with neuronal tissue in gray matter

Newer MRI methods can detect cerebral abnormalities not identified on routine imaging in patients with focal epilepsy. Correlation of MRI with histopathology is necessary to understand the basis of MRI abnormalities and subsequently predict histopathology from in vivo MRI. The aim of this study was to determine if particular quantitative MR parameters were associated with particular histological features.

Nine patients with temporal lobe epilepsy were imaged at 1.5 T using standard presurgical volumetric and quantifiable sequences: magnetization transfer and FFT2. The resected temporal lobe was registered with the volumetric MRI data according to our previously described method to permit correlation of the modalities. Stereologically measured neuronal densities and field fraction of GFAP, MAP2, synaptophysin and NeuN immunohistochemistry were obtained. Analyses were performed in the middle temporal gyrus and compared with quantitative MRI data from the equivalent regions.

There was a significant Spearman Rho negative correlation between NeuN field fraction and the T2 value in gray matter (correlation coefficient − 0.72, p = 0.028). There were no significant correlations between any neuropathological and MR measures in white matter.

These preliminary findings suggest that T2 in gray matter is sensitive to the proportion of neuronal tissue. Novel quantitative MRI measures acquired with higher field strength magnets, and so with superior signal to noise ratios, may generate data that correlate with histopathological measures. This will enable better identification and delineation of the structural causes of refractory focal epilepsy, and will be of particular benefit in patients in whom current optimal MRI does not identify a relevant abnormality.

Methodological aspects of 3D and automated 2D analyses of white matter neuronal density in temporal lobe epilepsy

White matter neuronal density has been correlated with clinical outcome after temporal lobectomy for refractory epilepsy. Both morphometric 2D (two-dimensional) and stereological 3D (three-dimensional) analyses of neuronal density have been performed. 3D analyses are thought to be more accurate than 2D counts, but more time-consuming. We compared 3D and automated 2D measurements in the same specimens. Adjacent 20-microm (for 3D analyses) and 5-microm (for 2D analyses) sections from 10 temporal lobectomies were stained for NeuN immunohistochemistry. Analysis of 100% of a region of interest (ROI) in deep white matter was performed using an image analysis system (Histometrix, Kinetic Imaging, UK). 3D analyses were undertaken using x 63 magnification (6 h/case). Automated 2D analyses were undertaken using automatic neuronal identification at x 10 magnification with three to four repeats (1.5 h/case). The range of neuronal densities for 3D measurements was 2120-4910 neurones/mm(3), and for automated 2D measurements 17.4-47.1 neurones/mm2. There was a linear correlation between the two methods with an r2 of 0.58. [corrected] Count-recount variability was 1.4-9.9% for the 3D and 5.1-36.6% for the automated 2D measurements. We found a wide range of white matter neuronal densities using either analysis. The low agreement between methods, and the high count-recount variability for the automated 2D analyses, indicate that despite being more time-consuming, rigorous 3D stereological analyses have to be performed to obtain reliable results. These findings have implications for studies requiring neuronal counts in normal and disease states.

Mixed glioneuronal tumour of the fourth ventricle with prominent rosette formation

We describe three unusual tumours characterized by a mixture of glial and neuronal differentiation, involvement of the posterior fossa and formation of rosettes. Mixed glial-neuronal tumours of the posterior fossa are rare and poorly described neoplasms. However, several distinctive entities have appeared in the literature over recent years under a variety of different names. Our cases demonstrate the morphological features of the 'rosette-forming glioneuronal tumour of the fourth ventricle', a recently identified tumour characterised by its unique location, neurocytic pseudo-rosette formation and the presence of a low grade astrocytoma component. The long term prognosis of these tumours remains unclear. However, the clinical data available including the cases presented here, along with the histological features, suggest that these are low grade tumours with a good prognosis after surgical resection.

The neuropathology of paraneoplastic syndromes

The term "paraneoplastic neurological syndromes" encompasses a number of uncommon disorders associated with systemic malignancies. In order to be classified a paraneoplastic neurological syndrome, the malignancies must not invade, compress, or metastasize to the nervous system. They can either focally or diffusely involve the central and peripheral nervous system or the neuromuscular junction. This paper reviews the neuropathology of the syndrome. It will first describe the clinical presentation and give an account of the systemic tumors most commonly associated with the various types of disorders. Then it will review the general pathological features that consist of an inflammatory process predominantly affecting the gray matter. Finally, it will describe in detail the main clinico-pathological types, including 1) encephalomyelitis, 2) cortical cerebellar degeneration, 3) peripheral neuropathy, 4) opsoclonus-myoclonus and 5) retinopathy. The Lambert-Eaton myasthenic syndrome will be dealt with separately in another paper in this symposium.

Vascular colocalization of P-glycoprotein, multidrug-resistance associated protein 1, breast cancer resistance protein and major vault protein in human epileptogenic pathologies

Multidrug transporters, such as P-glycoprotein (P-gp), multidrug-resistance associated protein 1 (MRP1) and breast cancer resistance protein (BCRP), are associated with multidrug resistance in cancers; other molecules, such as major vault protein (MVP), have a similar association with drug-resistant cancer. These proteins are postulated to generate drug resistance in epilepsy. They have been shown individually to be up-regulated in epileptogenic brain tissue. In any consideration of the function, inhibition or evasion of the activity of such proteins, the colocalization of such proteins needs to be understood. We systematically determined the presence of such colocalization, focusing on microvascular endothelium from epileptogenic human brain tissue. Double labelling immunofluorescence and confocal laser scanning microscopy were used to determine colocalization of P-gp, MRP1, BCRP and MVP in one case of hippocampal sclerosis and two cases of focal cortical dysplasia type IIb. Endothelial colocalization was examined with double labelling using antibodies to CD34 and Factor VIII. The presence of P-gp, BCRP and MVP in microvascular endothelium was confirmed. P-gp, BCRP and MVP colocalized in microvascular endothelium, though not all proteins appeared to be identically distributed within this tissue. MRP1 did not colocalize to endothelium. These findings were not unexpected but required formal confirmation. The demonstrated colocalization of P-gp, BCRP and MVP in microvascular endothelium in epileptogenic human brain tissue has important implications for functional experiments (including single knock-out mice studies), work with specific and broad-spectrum inhibitors of transport function, and any eventual trials of treatment of refractory epilepsy involving modulation of the function of these proteins.

Mcm2 labelling of balloon cells in focal cortical dysplasia

Balloon cells (BC) are the prominent and defining cellular component of type IIB Focal Cortical Dysplasia (FCD), a common cause of focal epilepsy in patients undergoing surgical treatment. BC are considered immature cells of uncommitted cellular differentiation having immunophenotypical characteristics of both neurones and glia. They are often located in the lower cortical layers and white matter underlying the dysplastic cortex, suggesting migratory arrest during development. We investigated the proliferative potential of BC in 15 cases of FCD from patients with a wide range of ages using immunohistochemistry for Mcm2 (mini chromosome maintenance protein) and Ki67. In the majority of cases, BC showed Mcm2 nuclear positivity. In addition, cells with intermediate neuronal-glial characteristics were labelled whilst the dysmorphic or hypertrophic pyramidal neuronal components of FCD were not. Ki67 labelled only occasional BC. These findings support the view that BC cells represent a pool of less differentiated glial cells with proliferative capacity which may have potential for delayed neuronal differentiation. Furthermore, as Mcm2 specifically identifies BC populations, this marker may be of diagnostic value in the subtyping of FCD lesions in patients with epilepsy.

ALK positive inflammatory myofibroblastic tumour of the pineal region

Inflammatory myofibroblastic tumours (IMTs) are an uncommon spindle cell neoplasm with a dense inflammatory infiltrate, usually encountered in children. IMTs of the central nervous system are extremely rare. This report describes the case of an IMT in a 61 year old man, in the pineal region. The tumour was completely excised, and immunohistochemistry demonstrated anaplastic lymphoma kinase 1 expression. There was no tumour recurrence during 18 months of follow-up. Our case extends both the age range and sites of occurrence of this rare tumour.

Cortical neuronal densities and lamination in focal cortical dysplasia

Focal cortical dysplasia (FCD) is considered to represent a malformation due to abnormal cortical development (MCD) and is an important cause of focal epilepsy. The histopathological features include abnormal laminar architecture, the presence of hypertrophic and dysmorphic neurones in FCD type IIA and additional balloon cells in FCD type IIB. The events causing these sporadic lesions are unknown, but abnormal progenitor cell proliferation occurring late in corticogenesis has been proposed. FCD-like lesions have, however, also been described following a cerebral injury early in life. We carried out a stereological assessment on 15 cases of FCD on NeuN- and Nissl-stained sections from patients with a wide age range, and identified a significant reduction in the neuronal density in all cases in the region of dysplasia compared to the adjacent unaffected cortex (mean neuronal densities 19.2x10(3)/mm3 in the region of dysplasia; 42.8x10(3)/mm3 in the adjacent cortex). Relative differences in neuronal density and size in FCD cases between the superficial (layer I and II) and deep cortical laminae (layer V and VI) were similar to that observed in other pathologies including mild MCD, temporal neocortex adjacent to hippocampal sclerosis as well as in a non-epilepsy surgical control group. The lower overall neuronal densities observed in FCD may reflect neuropil expansion, a local failure of neuronal migration, proliferation or secondary neuronal loss. The preservation of relative differences in neuronal densities between cortical layers and laminar patterns of neurofilament staining in FCD would support the view that the temporal sequence of lamination is not affected.

Development of detection methods for ruminant interleukin (IL)-4

Recombinant bovine IL-4 (rbo IL-4) was transiently expressed in COS-7 cells. Mice were immunised with a plasmid encoding rbo IL-4 and boosted with rbo IL-4. A number of monoclonal antibodies (mAb) were generated that reacted with rbo IL-4 in an ELISA and these cloned hybridomas were termed CC311, CC312, CC313 and CC314. A pair of mAb (CC313 and CC314) was identified that together could be used to detect both recombinant and native bovine IL-4 by ELISA and a luminometric detection method was applied to the ELISA. Using this method native bovine IL-4 was detected in supernatants of PBMC stimulated with mitogens. In addition, high level secretion of IL-4 by Fasciola hepatica specific Th2 clones, but not by a Babesia bovis specific Th1 clone, was confirmed. The ELISA was also able to detect recombinant ovine IL-4. The pair of mAb used for ELISA could also be used for the detection of IL-4 spot forming cells by ELISPOT. In addition intracytoplasmic expression of IL-4 could be detected. The ability to detect ruminant IL-4 by three methods: ELISA, ELISPOT and by flow cytometric analysis of intracytoplasmic expression will permit studies of the role of this important cytokine in the immunology and pathogenesis of animal diseases.

Brain biopsy in dementia

Brain biopsy has an uncertain role in the diagnosis of dementia. Here we report a retrospective analysis of 90 consecutive cerebral biopsies undertaken for the investigation of dementia in adults at a tertiary referral centre between 1989 and 2003. In most cases (90%), biopsy consisted of a right frontal full thickness resection of cortex, white matter and overlying leptomeninges. Fifty-seven per cent of biopsies were diagnostic: the most frequent diagnoses were Alzheimer's disease (18%), Creutzfeldt-Jakob disease (12%) and inflammatory disorders (9%). Other diagnoses in individual patients included Pick's disease, corticobasal degeneration and other tauopathies, Lewy body dementia, multiple sclerosis, Whipple's disease, progressive multifocal leucoencephalopathy, cerebral autosomal dominant arteriopathy with subcortical ischaemic leucoencephalopathy, vasculopathies and paraneoplastic encephalopathy. The most frequent biopsy finding in the non-diagnostic group and for the series as a whole (37%) was non-specific gliosis variably affecting both cortex and white matter. Complications (11%) included seizures, intracranial and wound infections, and intracranial haemorrhage; there were no deaths or lasting neurological sequelae attributable to the procedure. No trends in diagnostic yield or complication rate over the course of the series were identified. Information obtained at biopsy determined treatment in 11%. A raised cerebrospinal fluid cell count was the only robust predictor of a potentially treatable (inflammatory) process at biopsy. The constellation of behavioural change, raised CSF protein and matched oligoclonal bands in CSF and serum was associated with non-specific gliosis at biopsy. This series underlines the value of cerebral biopsy in the diagnosis of dementia, and suggests that certain clinical and laboratory features may be useful in guiding the decision to proceed to brain biopsy where a treatable disease cannot be excluded by other means.

The effect of repeated tuberculin skin testing of cattle on immune responses and disease following experimental infection with Mycobacterium bovis

The comparative intradermal skin test, in which a delayed type hypersensitivity (DTH) response to purified protein derivative of tuberculin (PPD) from Mycobacterium bovis and M. avium is assessed and compared, may be used repeatedly on non-infected animals on farms where bovine tuberculosis (TB) has occurred. A skin test is known to affect subsequent skin tests in infected animals. The reported study was to determine whether repeated skin testing prior to infection with M. bovis might affect the development of the comparative skin test and IFNgamma response subsequent to exposure to virulent M. bovis. The comparative intradermal skin test was applied to one group of six calves five times at 8-week intervals. These and six control calves were subsequently inoculated intratracheally with a dose of M. bovis that produced mild disease. The development of the DTH reaction, IFNgamma, IL-10 and proliferative responses were compared in the two groups of animals. No differences in IFNgamma, IL-10 and proliferative responses were seen between the two groups of calves prior to challenge. After infection with M. bovis no differences in the development of the DTH and IFNgamma responses to PPD were noted as a consequence of the repeated skin testing prior to challenge. No differences between the groups were evident when ESAT-6 was used as antigen and IFNgamma was assayed, although two animals that responded to PPD did not respond with ESAT-6. However, there did appear to be subtle effects of repeated skin testing on the immune response post-challenge that did not affect the diagnostic tests. After challenge control animals showed greater proliferative responses than animals given repeated skin tests prior to challenge, indicating that the procedure did have consequences for immune responses following infection. In both groups a marked reduction in the intensity of the skin test and in the number of animals that would be recognized as reactors was evident when animals were tested 15 weeks post-infection compared to their responses 8 weeks earlier that could have consequences for diagnosis of TB. An antibody response was not evident as a result of repeat skin testing prior to infection but was seen in both groups of calves following skin testing performed 7 weeks after infection.

Cajal-Retzius cells, inhibitory interneuronal populations and neuropeptide Y expression in focal cortical dysplasia and microdysgenesis

Focal cortical dysplasia (FCD) and microdysgenesis (MD) are likely to represent abnormalities of radial neuronal migration during cortical development. We investigated the distribution of reelin-positive Cajal-Retzius cells, known to be important in the later stages of radial neuronal migration and cortical organization, in 12 surgical cases of both MD and FCD. Quantitation revealed significantly higher numbers of these cells in MD cases compared to controls. As the majority of cortical interneurones arise via tangential rather than radial migration, we studied the distribution and morphology of inhibitory interneuronal subsets immunolabelled for calbindin, parvalbumin and calretinin within these malformations. Frequent findings were a reduction of inhibitory interneurones in the region of FCD and abnormally localised hypertrophic or multipolar calbindin-positive interneurones in both FCD and MD. Neuropeptide Y immunostaining showed a striking increase in the density of the superficial plexus of fibres in both MD and FCD cases in addition to labelling of dysplastic neurones, which may represent an adaptive anti-convulsant mechanism to dampen down seizure propagation.

Sudden and unexpected death in epilepsy (SUDEP): evidence of acute neuronal injury using HSP-70 and c-Jun immunohistochemistry

Post-mortem and neuropathological examination in sudden and unexpected death in epilepsy (SUDEP) shows no specific lesions and the exact cause and mechanism of death in these cases remains undetermined. There is clinical evidence to support the fact that SUDEP is a seizure-mediated event, and patients with poorly controlled seizures are at higher risk. We aimed to identify any evidence of acute neuronal injury in SUDEP cases at post-mortem to support that a recent seizure had occurred. We analysed the distribution and frequency of heat shock protein (HSP)-70 and c-Jun immunopositive neurones in the hippocampus in 18 SUDEP cases and 22 control cases, both markers being nonspecific but early and reliable indicators of acute neuronal injury. Post-mortem control groups included patients with epilepsy with cause of death other than SUDEP (including status epilepticus and accidental death), and patients with sudden cardiac death without an epilepsy history. An additional surgical control group included patients with refractory epilepsy and hippocampal sclerosis who had undergone temporal lobectomy. Semiquantitative analysis of the distribution of HSP-70 staining showed significantly more SUDEP cases with positively labelled neurones in hippocampal subfields compared to epilepsy and cardiac post-mortem controls (P < 0.001) but not compared to the epilepsy surgical controls (P = 0.4). No significant difference in immunostaining patterns between groups was seen in the parahippocampal gyrus with HSP-70 or with c-Jun in either the hippocampus or parahippocampal gyrus regions. The detection of HSP-70 positive neurones in the hippocampus in SUDEP is supportive of ante-mortem neuronal injury including a recent seizure prior to death.

GABA(B1a), GABA(B1b) AND GABA(B2) mRNA variants expression in hippocampus resected from patients with temporal lobe epilepsy

The aim of this study was to investigate the mRNA expression of the two GABA(B1) receptor isoforms and the GABA(B2) subunit, in human postmortem control hippocampal sections and in sections resected from epilepsy patients using quantitative in situ hybridisation autoradiography. Utilising human control hippocampal sections it was shown that the oligonucleotides employed were specific to the receptor. Hippocampal slices from surgical specimens obtained from patients with hippocampal sclerosis and temporal lobe epilepsy were compared with neurologically normal postmortem control subjects for neuropathology and GABA(B) mRNA expression. Neuronal loss was observed in most of the hippocampal subregions, but in the subiculum no significant difference was detected. The localisation of GABA(B1a) and GABA(B1b) isoform mRNAs in human control hippocampal sections supported and extended earlier studies using the GABA(B1) pan probe, which does not distinguish between the two GABA(B1) isoforms. Moreover, the GABA(B2) mRNA location confirmed the heterodimerisation of the receptor. Thus, although there was an apparent correlation between GABA(B1b) and GABA(B2), GABA(B1a) exhibited no such relationship. GABA(B1b) and GABA(B2) showed a similar intensity of expression whilst GABA(B1a) displayed a lower hybridisation signal. Comparison of the expression of the three mRNAs between control and epileptic subjects showed significant decreases or increases in different hippocampal subregions.GABA(B) isoforms and subunit mRNA expression per remaining neuron was significantly increased in the hilus and dentate gyrus. These results demonstrate that altered GABA(B) receptor mRNA expression occurs in human TLE; possibly the observed changes may also serve to counteract ongoing hyperexcitability.

Drug resistance in epilepsy: human epilepsy

The basis of drug resistance in human epilepsy is not understood. Parallels with resistance in cancer suggest that drug resistance proteins may have a role. To examine this possibility, we have studied human brain tissue containing pathologies capable of causing refractory epilepsy. Using immunohistochemistry for P glycoprotein (Pgp) and multidrug resistance-associated protein 1 (MRP1), we examined both pathological tissue and control tissue. We demonstrate expression of Pgp and MRP1 in glia from cases of malformation of cortical development studied both before and after the onset of epilepsy, as well as in cases of hippocampal sclerosis and dysembryoplastic neuroepithelial tumours. In one particular type of malformation, we also demonstrate that dysplastic neurons express MRP1. The pattern of immunolabelling suggests overexpression is concentrated particularly around vessels in most of the pathologies. The timing shows that expression may be constitutive in some pathologies. These findings suggest that drug resistance proteins may contribute to drug resistance in refractory epilepsy.

Abnormalities of grey and white matter [11C]flumazenil binding in temporal lobe epilepsy with normal MRI

In 20% of potential surgical candidates with refractory epilepsy, current optimal MRI does not identify the cause. GABA is the principal inhibitory neurotransmitter in the brain, and GABA(A) receptors are expressed by most neurones. [(11)C]Flumazenil (FMZ) PET images the majority of GABA(A) receptor subtypes. We investigated abnormalities of FMZ binding in grey and white matter in 18 patients with refractory temporal lobe epilepsy (TLE) and normal quantitative MRI. Parametric images of FMZ volume of distribution (FMZ-V(d)) were calculated. Twenty-one healthy controls were scanned for comparison. Statistical parametric mapping (SPM99) was used to localize significant changes in FMZ-V(d) in individual patients and between groups, specifically including the entire white matter in all subjects through explicit masking. Sixteen of 18 patients showed single or multiple abnormalities of FMZ-V(d). Six had hippocampal decreases of FMZ-V(d). Eleven patients showed increased FMZ-V(d) in the temporal lobe white matter (TLWM). Outside the mesial temporal structures, seven showed multiple areas of increase or decrease and only one a single area of decrease. In seven of the 16 patients with abnormalities, findings were concordant with EEG and clinical data, enabling further presurgical evaluation. Group findings were: (i) decreased FMZ-V(d) in the ipsilateral (Z = 3.01) and contralateral (Z = 2.56) hippocampus; (ii) increased FMZ-V(d) in the ipsilateral (Z = 3.71) and contralateral TLWM (two clusters, Z = 3.11 and 2.79); and (iii) increased FMZ-V(d) in the ipsilateral frontal lobe white matter between the superior and medial frontal gyrus (Z = 3.80) with similar changes contralaterally (Z = 4.87). No changes were found in the thalamus and basal ganglia. Region-of-interest analyses indicated an average increase in FMZ binding of 16% in the TLWM ipsilateral to the epileptic focus. PET findings were corroborated by invasive EEG or pathology in five cases. FMZ-PET, analysed by SPM with explicit masking, was sensitive in patients with normal MRI, and hippocampal abnormalities were detected in a third of these patients. Furthermore, increases in FMZ binding in TLWM, indicating microdysgenesis, were detected in the majority of these patients and may represent the structural basis of their epilepsy.

Studies of GABA(B) receptors labelled with [(3)H]-CGP62349 in hippocampus resected from patients with temporal lobe epilepsy

1 The aim of this study was to investigate the binding of a novel GABA(B) receptor radioligand, [(3)H]-CGP62349, to human post-mortem control and epileptic hippocampal sections using quantitative receptor autoradiography. Utilizing human control hippocampal sections it was shown that [(3)H]-CGP62349 bound with high affinity (K(D) 0.5 nM) to this tissue. 2 Hippocampal slices from surgical specimens obtained from patients with hippocampal sclerosis (HS) and temporal lobe epilepsy (TLE) were compared with neurologically normal post-mortem control subjects for neuropathology and GABA(B) receptor density and affinity. Neuronal loss was observed in most of the hippocampal subregions, but in the subiculum no significant difference was detected. 3 The localization of GABA(B) receptors with the antagonist [(3)H]-CGP62349 in human control hippocampal sections supported and extended earlier studies using the agonist ligand [(3)H]-GABA. 4 The kinetics of binding to the GABA(B) receptor in human hippocampus using this novel compound was comparable to previous data obtained in rat hippocampal membranes. 5 GABA(B) receptor density (B(max)) was significantly reduced in CA3, hilus, and dentate gyrus (DG); the affinity was increased exclusively in DG. The trend is identical in all the hippocampal subregions with the agonist and the antagonist, although significant differences with the antagonist where recorded in CA3 and hilus, whereas with the agonist a significant reduction was reported in all of the hippocampal subfields. 6 GABA(B) receptor expression per remaining neuron appeared significantly increased in CA3 and hilus. These results suggest altered GABA(B) receptor function may occur in human TLE, possibly as a result of synaptic reorganization, and may contribute to epileptogenesis.

Bilateral isolated hippocampal malformation in temporal lobe epilepsy

Hippocampal malformations in patients with epilepsy usually are reported in the context of widespread cortical malformations. Isolated hippocampal malformations are more rarely identified in MRI studies with little documentation of their pathologic appearance. Postmortem examination revealed abnormal position and complex convolutional malformations isolated to the hippocampal formation in an adult with temporal lobe epilepsy in whom MRI demonstrated bilateral hippocampal abnormalities.

Progesterone receptors are expressed with higher frequency by optic nerve sheath meningiomas

Optic nerve sheath meningiomas are infrequent neuropathological specimens as conservative management of these benign tumors is often adopted. It is established that progesterone receptor expression in meningiomas may be of functional significance in the growth of these neoplasms and is related to the tumor grade and likelihood of recurrence. In addition, progesterone receptor expression can be indicative of a potential response of surgically less accessible meningiomas to hormonal treatments. We analyzed 30 surgically resected optic nerve sheath meningiomas and showed high levels of progesterone receptor expression compared to benign meningiomas from other intracranial sites suggesting these tumors may be amenable to hormonal therapy.