Progressive multifocal leukoencephalopathy and Creutzfeldt-Jakob disease: population-wide incidences, comorbidities, costs of care, and outcomes.

Neurological disorders associated with chronic infections are often progressive as well as challenging to diagnose and manage. Among 4.4 million persons from 2004 to 2019 receiving universal health, progressive multifocal leukoencephalopathy (PML, n = 58) and Creutzfeldt-Jakob disease (CJD, n = 93) cases were identified, revealing stable yearly incidence rates with divergent comorbidities: HIV/AIDS affected 37.8% of PML cases while cerebrovascular disease affected 26.9% of CJD cases. Most CJD cases died within 1 year (73%) although PML cases lived beyond 5 years (34.1%) despite higher initial costs of care. PML and CJD represent important neurological disorders with evolving risk variables and impact on health care.

Diagnostic Accuracy of Centrally Restricted Diffusion in the Differentiation of Treatment-Related Necrosis from Tumor Recurrence in High-Grade Gliomas.

BACKGROUND AND PURPOSE: Centrally restricted diffusion has been demonstrated in recurrent high-grade gliomas treated with bevacizumab. Our purpose was to assess the accuracy of centrally restricted diffusion in the diagnosis of radiation necrosis in high-grade gliomas not treated with bevacizumab. MATERIALS AND METHODS: In this prospective study, we enrolled patients with high-grade gliomas who developed a new ring-enhancing necrotic lesion and who underwent re-resection. The presence of a centrally restricted diffusion within the ring-enhancing lesion was assessed visually on diffusion trace images and by ADC measurements on 3T preoperative diffusion tensor examination. The percentage of tumor recurrence and radiation necrosis in each surgical specimen was defined histopathologically. The association between centrally restricted diffusion and radiation necrosis was assessed using the Fisher exact test. Differences in ADC and the ADC ratio between the groups were assessed via the Mann-Whitney U test, and receiver operating characteristic curve analysis was performed. RESULTS: Seventeen patients had re-resected ring-enhancing lesions: 8 cases of radiation necrosis and 9 cases of tumor recurrence. There was significant association between centrally restricted diffusion by visual assessment and radiation necrosis (P = .015) with a sensitivity of 75% and a specificity of 88.9%, a positive predictive value 85.7%, and a negative predictive value of 80% for the diagnosis of radiation necrosis. There was a statistically significant difference in the ADC and ADC ratio between radiation necrosis and tumor recurrence (P = .027). CONCLUSIONS: The presence of centrally restricted diffusion in a new ring-enhancing lesion might indicate radiation necrosis rather than tumor recurrence in high-grade gliomas previously treated with standard chemoradiation without bevacizumab.

Correlation of Tumor Immunohistochemistry with Dynamic Contrast-Enhanced and DSC-MRI Parameters in Patients with Gliomas.

BACKGROUND AND PURPOSE: Tumor CBV is a prognostic and predictive marker for patients with gliomas. Tumor CBV can be measured noninvasively with different MR imaging techniques; however, it is not clear which of these techniques most closely reflects histologically-measured tumor CBV. Our aim was to investigate the correlations between dynamic contrast-enhanced and DSC-MR imaging parameters and immunohistochemistry in patients with gliomas. MATERIALS AND METHODS: Forty-three patients with a new diagnosis of glioma underwent a preoperative MR imaging examination with dynamic contrast-enhanced and DSC sequences. Unnormalized and normalized cerebral blood volume was obtained from DSC MR imaging. Two sets of plasma volume and volume transfer constant maps were obtained from dynamic contrast-enhanced MR imaging. Plasma volume obtained from the phase-derived vascular input function and bookend T1 mapping (Vp_Φ) and volume transfer constant obtained from phase-derived vascular input function and bookend T1 mapping (Ktrans_Φ) were determined. Plasma volume obtained from magnitude-derived vascular input function (Vp_SI) and volume transfer constant obtained from magnitude-derived vascular input function (Ktrans_SI) were acquired, without T1 mapping. Using CD34 staining, we measured microvessel density and microvessel area within 3 representative areas of the resected tumor specimen. The Mann-Whitney U test was used to test for differences according to grade and degree of enhancement. The Spearman correlation was performed to determine the relationship between dynamic contrast-enhanced and DSC parameters and histopathologic measurements. RESULTS: Microvessel area, microvessel density, dynamic contrast-enhanced, and DSC-MR imaging parameters varied according to the grade and degree of enhancement (P < .05). A strong correlation was found between microvessel area and Vp_Φ and between microvessel area and unnormalized blood volume (rs ≥ 0.61). A moderate correlation was found between microvessel area and normalized blood volume, microvessel area and Vp_SI, microvessel area and Ktrans_Φ, microvessel area and Ktrans_SI, microvessel density and Vp_Φ, microvessel density and unnormalized blood volume, and microvessel density and normalized blood volume (0.44 ≤ rs ≤ 0.57). A weaker correlation was found between microvessel density and Ktrans_Φ and between microvessel density and Ktrans_SI (rs ≤ 0.41). CONCLUSIONS: With dynamic contrast-enhanced MR imaging, use of a phase-derived vascular input function and bookend T1 mapping improves the correlation between immunohistochemistry and plasma volume, but not between immunohistochemistry and the volume transfer constant. With DSC-MR imaging, normalization of tumor CBV could decrease the correlation with microvessel area.

Comparison of the Diagnostic Accuracy of DSC- and Dynamic Contrast-Enhanced MRI in the Preoperative Grading of Astrocytomas.

BACKGROUND AND PURPOSE: Dynamic contrast-enhanced MR imaging parameters can be biased by poor measurement of the vascular input function. We have compared the diagnostic accuracy of dynamic contrast-enhanced MR imaging by using a phase-derived vascular input function and "bookend" T1 measurements with DSC MR imaging for preoperative grading of astrocytomas. MATERIALS AND METHODS: This prospective study included 48 patients with a new pathologic diagnosis of an astrocytoma. Preoperative MR imaging was performed at 3T, which included 2 injections of 5-mL gadobutrol for dynamic contrast-enhanced and DSC MR imaging. During dynamic contrast-enhanced MR imaging, both magnitude and phase images were acquired to estimate plasma volume obtained from phase-derived vascular input function (Vp_Φ) and volume transfer constant obtained from phase-derived vascular input function (K(trans)_Φ) as well as plasma volume obtained from magnitude-derived vascular input function (Vp_SI) and volume transfer constant obtained from magnitude-derived vascular input function (K(trans)_SI). From DSC MR imaging, corrected relative CBV was computed. Four ROIs were placed over the solid part of the tumor, and the highest value among the ROIs was recorded. A Mann-Whitney U test was used to test for difference between grades. Diagnostic accuracy was assessed by using receiver operating characteristic analysis. RESULTS: Vp_ Φ and K(trans)_Φ values were lower for grade II compared with grade III astrocytomas (P < .05). Vp_SI and K(trans)_SI were not significantly different between grade II and grade III astrocytomas (P = .08-0.15). Relative CBV and dynamic contrast-enhanced MR imaging parameters except for K(trans)_SI were lower for grade III compared with grade IV (P ≤ .05). In differentiating low- and high-grade astrocytomas, we found no statistically significant difference in diagnostic accuracy between relative CBV and dynamic contrast-enhanced MR imaging parameters. CONCLUSIONS: In the preoperative grading of astrocytomas, the diagnostic accuracy of dynamic contrast-enhanced MR imaging parameters is similar to that of relative CBV.

Preoperative prognostic value of dynamic contrast-enhanced MRI-derived contrast transfer coefficient and plasma volume in patients with cerebral gliomas.

BACKGROUND AND PURPOSE: The prognostic value of dynamic contrast-enhanced MR imaging-derived plasma volume obtained in tumor and the contrast transfer coefficient has not been well-established in patients with gliomas. We determined whether plasma volume and contrast transfer coefficient in tumor correlated with survival in patients with gliomas in addition to other factors such as age, type of surgery, preoperative Karnofsky score, contrast enhancement, and histopathologic grade. MATERIALS AND METHODS: This prospective study included 46 patients with a new pathologically confirmed diagnosis of glioma. The contrast transfer coefficient and plasma volume obtained in tumor maps were calculated directly from the signal-intensity curve without T1 measurements, and values were obtained from multiple small ROIs placed within tumors. Survival curve analysis was performed by dichotomizing patients into groups of high and low contrast transfer coefficient and plasma volume. Univariate analysis was performed by using dynamic contrast-enhanced parameters and clinical factors. Factors that were significant on univariate analysis were entered into multivariate analysis. RESULTS: For all patients with gliomas, survival was worse for groups of patients with high contrast transfer coefficient and plasma volume obtained in tumor (P < .05). In subgroups of high- and low-grade gliomas, survival was worse for groups of patients with high contrast transfer coefficient and plasma volume obtained in tumor (P < .05). Univariate analysis showed that factors associated with lower survival were age older than 50 years, low Karnofsky score, biopsy-only versus resection, marked contrast enhancement versus no/mild enhancement, high contrast transfer coefficient, and high plasma volume obtained in tumor (P < .05). In multivariate analysis, a low Karnofsky score, biopsy versus resection in combination with marked contrast enhancement, and a high contrast transfer coefficient were associated with lower survival rates (P < .05). CONCLUSIONS: In patients with glioma, those with a high contrast transfer coefficient have lower survival than those with low parameters.

Diagnostic accuracy of dynamic contrast-enhanced MR imaging using a phase-derived vascular input function in the preoperative grading of gliomas.

BACKGROUND AND PURPOSE: The accuracy of tumor plasma volume and K(trans) estimates obtained with DCE MR imaging may have inaccuracies introduced by a poor estimation of the VIF. In this study, we evaluated the diagnostic accuracy of a novel technique by using a phase-derived VIF and "bookend" T1 measurements in the preoperative grading of patients with suspected gliomas. MATERIALS AND METHODS: This prospective study included 46 patients with a new pathologically confirmed diagnosis of glioma. Both magnitude and phase images were acquired during DCE MR imaging for estimates of K(trans)_φ and V(p_)φ (calculated from a phase-derived VIF and bookend T1 measurements) as well as K(trans)_SI and V(p_)SI (calculated from a magnitude-derived VIF without T1 measurements). RESULTS: Median K(trans)_φ values were 0.0041 minutes(-1) (95 CI, 0.00062-0.033), 0.031 minutes(-1) (0.011-0.150), and 0.088 minutes(-1) (0.069-0.110) for grade II, III, and IV gliomas, respectively (P ≤ .05 for each). Median V(p_)φ values were 0.64 mL/100 g (0.06-1.40), 0.98 mL/100 g (0.34-2.20), and 2.16 mL/100 g (1.8-3.1) with P = .15 between grade II and III gliomas and P = .015 between grade III and IV gliomas. In differentiating low-grade from high-grade gliomas, AUCs for K(trans)_φ, V(p_φ), K(trans)_SI, and V(p_)SI were 0.87 (0.73-1), 0.84 (0.69-0.98), 0.81 (0.59-1), and 0.84 (0.66-0.91). The differences between the AUCs were not statistically significant. CONCLUSIONS: K(trans)_φ and V(p_)φ are parameters that can help in differentiating low-grade from high-grade gliomas.

Mutations in KRT5 and KRT14 cause epidermolysis bullosa simplex in 75% of the patients.

BACKGROUND: Epidermolysis bullosa simplex (EBS) is a mechanobullous genodermatosis that may be caused by mutations in the genes KRT5 and KRT14 encoding the basal epidermal keratins 5 (K5) and 14 (K14). Three main clinical subtypes of EBS exist, differing in onset, distribution and severity of skin blistering. Previous reports of KRT5 and KRT14 mutations suggest a correlation between the location of the mutation and the severity of the associated EBS phenotype. OBJECTIVES: The prevalence of KRT5/KRT14 mutations and the genotype-phenotype correlation in the largest tissue-confirmed EBS population is investigated. METHODS: KRT5 and KRT14 genomic DNA and cDNA sequences of 76 clinically well-defined unrelated EBS probands were amplified and then subjected to direct sequencing and product length analysis. Immunofluorescence microscopy on patients' skin biopsies with antibodies against K5 and K14 was performed to study protein expression. RESULTS: In 57 of 76 (75%) probands 41 different KRT5 and KRT14 mutations were identified, of which 12 were novel. Mutations affecting the highly conserved helix boundary motifs of the rod domains of K5 and K14, and the K14 helix initiation motif in particular, were associated with the severest, EBS Dowling-Meara, phenotype. In 21 EBS probands (37%) the mutation was de novo. In 19 probands (25%) KRT5 or KRT14 mutations were excluded. CONCLUSIONS: The phenotype-genotype correlation observed in this large EBS population underscores the importance of helix boundary motifs for keratin assembly. Only three-quarters of biopsy-confirmed EBS probands have KRT5 or KRT14 mutations, indicating genetic heterogeneity in EBS. Alternative gene candidates are discussed.

Effects of fulvestrant alone or combined with different steroids in human breast cancer cells in vitro.

OBJECTIVES: Fulvestrant is an estrogen receptor (ER) antagonist that binds, blocks and degrades the estrogen receptor and is currently used in adjuvant treatment in postmenopausal women with ER-positive breast cancer as an alternative for tamoxifen. As an antagonist, it may induce or aggravate climacteric symptoms. In order to alleviate these symptoms, one could consider hormone therapy. The objective of this study was to analyze the effect of fulvestrant alone or in combination with different steroids in human breast cancer cells in vitro, and to demonstrate whether these steroids will compromise the efficacy of fulvestrant in ER-positive breast cancer cells. METHODS: We performed experiments in vitro with various hormone therapy preparations (estradiol (E2), dihydrodydrogesterone (DHD) and tibolone) at a concentration of 10(-6) mol/l alone or combined with fulvestrant in different breast cancer cell lines, ER-positive and ER-negative. After an incubation of 144 h, proliferation and apoptosis were measured. The first was measured by quantification of the expression of cyclin D1 mRNA, the latter by the Nicoletti fragmentation assay. RESULTS: This in vitro study revealed clear differences in results when various hormone therapy preparations, alone or combined with fulvestrant, are added to ER-positive and ER-negative breast cancer cell lines. CONCLUSIONS: Our study demonstrated that fulvestrant, an ER antagonist used in the treatment of ER-positive breast cancer, combined with E2 and DHD or in combination with tibolone, is not compromised in its efficacy in inducing apoptosis in ER-positive breast cancer cell lines in vitro.

[Diagnostic image (336). A woman with a calcified pelvic mass]. / Diagnose in beeld (336). Een vrouw met een verkalkte pelviene massa.

In a 34-year-old woman with uterine fibroids, one of the fibroids was calcified and was therefore visible on a conventional radiograph.

Voxel-based analysis of the evolution of magnetization transfer ratio to quantify remyelination and demyelination with histopathological validation in a multiple sclerosis lesion.

We present a new method for advanced image processing to separately quantify significant decreases and increases in the magnetization transfer ratio (MTR) of individual voxels of MS lesions as markers of demyelination and remyelination. We used this method to analyze the evolution of MTR in individual voxels of an acute, Gadolinium (Gd)-enhancing lesion that was available for pathology. Over 6.5 months following enhancement, MTR was low and stable in the lesion center (81% of the initially Gd-enhancing lesion volume (GdLV)) and MTR increased at the lesion border with normal-appearing white matter (14%GdLV). The estimated error of these measurements was less than 1.8%GdLV based on scan/rescan analysis. Histopathological analysis confirmed a demyelinated lesion centre with diffuse presence of macrophages/microglia and marked loss of oligodendrocytes and a partially remyelinated lesion border with diffuse presence of macrophages/microglia and relatively more oligodendrocytes compared to the lesion centre. The correlation of imaging and histopathological findings support the validity and sensitivity of our method of voxel-based MTR image processing for monitoring demyelination and remyelination in vivo.

The role of quantitative electromyography (EMG) in horses suspected of acute and chronic grass sickness.

REASONS FOR PERFORMING THE STUDY: Clinical evidence of motor neuron involvement in equine grass sickness (EGS) has not been reported. HYPOTHESIS: Quantitative electromyography (EMG) analysis can elucidate subtle changes of the lower motor neuron system present in horses with EGS, performed ante mortem. METHODS: Fourteen horses diagnosed clinically with acute, subacute or chronic EGS were examined and quantitative EMG performed. Previously published data on healthy horses and horses with proven lower motor neuron disease (LMND) were used as controls. In 8 horses post mortem examination was performed, and in 7 muscle biopsies of the lateral vastus muscle underwent histopathology and morphometry. RESULTS: Clinical electrophysiological evidence of neuropathy was present in 12 horses. Analysis of data from the first 4 horses resulted in 95% confidence intervals (CI) of nontransformed data for motor unit action potential (MUP) duration in subclavian, triceps and lateral vastus muscle of 11.0-13.7, 14.8-20.3 and 12.2-17.2 msecs, respectively, and for MUP amplitude 291-453, 1026-1892 and 957-1736 microV, respectively. For number of phases the 95% CI was 3.6-4.4, 2.9-3.6 and 2.9-3.4, respectively, and for number of turns 5.0-6.5, 4.3-5.3 and 3.7-4.6, respectively. No changes in duration of insertional activity were measured. Pathological spontaneous activity was observed in all horses. EGS as evidenced by degenerative changes in the autonomic ganglia in combination with minor degenerative changes of the spinal lower motor neurons was observed on post mortem examination in all 8 available autopsies. In muscle biopsies of 4 out of 7 horses changes consistent with slight neurogenic atrophy were found. CONCLUSIONS AND POTENTIAL RELEVANCE: EMG results demonstrated the presence of a neuropathy of skeletal muscles in all horses suspected to have EGS. The combination of clinical and electrophysiological evidence may aid differential diagnosis of neurogenic disease in cases of weight loss and colic.

Expression and cellular distribution of multidrug transporter proteins in two major causes of medically intractable epilepsy: focal cortical dysplasia and glioneuronal tumors.

The cell-specific distribution of multidrug resistance extrusion pumps was studied in developmental glioneuronal lesions, including focal cortical dysplasia (15 cases) and ganglioglioma (15 cases) from patients with medically intractable epilepsy. Lesional, perilesional, as well as normal brain regions were examined for the expression of the multidrug resistance gene 1 encoded P-glycoprotein (P-gp) and the multidrug resistance-associated protein 1 (MRP1) by immunocytochemistry. In normal brain MRP1 expression was below detection, whereas P-gp staining was present only in blood vessels. MRP1 and P-gp immunoreactivity was observed in dysplastic neurons of 11/15 cases of focal cortical dysplasia, as well as in the neuronal component of 14/15 ganglioglioma. Glial cells with astrocytic morphology within the lesion showed multidrug-resistant protein immunoreactivity (P-gp>MRP1). Moderate to strong MRP1 and P-gp immunoreactivity was observed in a population of large ballooned neuroglial cells. P-gp appeared to be most frequently expressed in glial fibrillary acidic protein-positive balloon cells (glial type), whereas MRP1 was more frequently expressed in microtubule-associated protein 2-positive balloon cells (neuronal type). In both types of lesions strong P-gp immunoreactivity was found in lesional vessels. Perilesional regions did not show increased staining in vessels or in neuronal cells compared with normal cortex. The predominant intralesional cell-specific distribution of multidrug transporter proteins supports the hypothesis of a constitutive overexpression as common mechanism underlying the intrinsic pharmaco-resistance to antiepileptic drugs of both malformative and neoplastic glioneuronal developmental lesions.

A novel germline mutation of PTEN associated with brain tumours of multiple lineages.

We have identified a novel germline mutation in the PTEN tumour suppressor gene. The mutation was identified in a patient with a glioma, and turned out to be a heterozygous germline mutation of PTEN (Arg234Gln), without loss of heterozygosity in tumour DNA. The biological consequences of this germline mutation were investigated by means of transfection studies of the mutant PTEN molecule compared to wild-type PTEN. In contrast to the wild-type molecule, the mutant PTEN protein is not capable of inducing apoptosis, induces increased cell proliferation and leads to high constitutive PKB/Akt activation, which cannot be increased anymore by stimulation with insulin. The reported patient, in addition to glioma, had suffered from benign meningioma in the past but did not show any clinical signs of Cowden disease or other hereditary diseases typically associated with PTEN germline mutations. The functional consequences of the mutation in transfection studies are consistent with high proliferative activity. Together, these findings suggest that the Arg234Gln missense mutation in PTEN has oncogenic properties and predisposes to brain tumours of multiple lineages.

[Creutzfeldt-Jakob disease: diagnosis, incidence, prevention and treatment]. / Ziekte van Creutzfeldt-Jakob: diagnostiek, incidentie, preventie en behandeling.

Creutzfeldt-Jakob disease (CJD) is a rare, neurodegenerative disorder belonging to the spongiform encephalopathies. A variant form (vCJD) is most likely the result of infection with the agent that causes bovine spongiform encephalopathy (BSE). Diagnostic information can be obtained by EEG, testing cerebrospinal fluid for the presence of the 14-3-3 protein, MRI, brain biopsy, tonsil biopsy, and postmortem brain examination. Some tests, such as MRI and postmortem brain examination, can be used to distinguish between CJD and vCJD. Pathological prions in a tonsil biopsy are only found with vCJD. In the Netherlands, there are four known cases of iatrogenic CJD. On the basis of certain exposure to BSE via the food chain, cases of vCJD are also to be expected. Chloropromazine and mepacrine are known to inhibit the formation of pathological prion conformations, but clinical trials have not yet been carried out.

Patients with persistent pain after enucleation studied by MRI dynamic color mapping and histopathology.

PURPOSE: To study possible causes of persistent pain in patients who underwent enucleation of the globe and in whom all other noninvasively detectable causes of pain had been ruled out. METHODS: Twenty patients were studied, 10 with intractable pain (score >5 on a 0-to-9 self-reporting pain scale) persisting for more than 6 months after enucleation (for various reasons) and 10 without pain (score <4) at least 6 months after enucleation. Magnetic resonance imaging (MRI) with dynamic color mapping (MRI-DCM) was used to quantify the motion of the optic nerve in millimeters per degree of gaze, 2 to 3 mm behind the implant. Histopathologic study of biopsy specimens was used to verify imaging findings. RESULTS: The optic nerve was attached to the implant in almost all (19/20) patients. On average, the motion was significantly less in patients with persistent intractable pain (0.04 mm/deg) than in patients without pain (0.08 mm/deg; normal orbit, 0.13 mm/deg). A biopsy specimen was available in 5 of 10 patients with persistent pain, and in 4 of those 5, microscopic neuroma was found close to the optic nerve-implant junction. CONCLUSIONS: In the enucleated orbit, the optic nerve is usually attached to the implant and soft tissue motion is decreased. In patients who have persistent pain after enucleation, motion is decreased even more, and a high percentage of microscopic amputation neuromas are found. Increased stiffness of orbital soft tissue and optic nerve attachment after enucleation are detectable using MRI-DCM, and may play a role in susceptible patients in the development of microscopic amputation neuroma and pain.

Ionotropic and metabotropic glutamate receptor protein expression in glioneuronal tumours from patients with intractable epilepsy.

Glioneuronal tumours are an increasingly recognized cause of chronic pharmaco-resistant epilepsy. In the present study the immunocytochemical expression of various glutamate receptor (GluR) subtypes was investigated in 41 gangliogliomas (GG) and 16 dysembryoplastic neuroepithelial tumours (DNT) from patients with intractable epilepsy. Immunocytochemistry with antibodies specific for ionotropic NR1, NR2A/B (NMDA) GluR1, GluR2 (AMPA), GluR5-7 (kainate), and metabotropic mGluR1, mGluR2-3, mGluR5, mGluR7a subtypes demonstrated in both GG and DNT the presence of an highly differentiated neuronal population, containing subunits from each receptor class. More than 50% of tumours contained a high percentage of neuronal cells immunolabelled for NMDA, AMPA and kainate receptor subunits. A high percentage of neurones showed strong expression of NR2A-B, which co-localized with NR1. Group I mGluRs (mGluR1 and mGluR5) were highly represented in the neuronal component of the tumours. Immunolabelling for several GluRs was also present in the glial component. Increased expression of mGluR2-3, mGluR5 and GluR5-7 was observed in reactive astrocytes in the perilesional zone compared to normal cortex. The neurochemical profile of glioneuronal tumours, with high expression of specific GluR subtypes, supports the central role of glutamatergic transmission in the mechanisms underlying the intrinsic and high epileptogenicity of these lesions.

Expression of connexin 43 and connexin 32 gap-junction proteins in epilepsy-associated brain tumors and in the perilesional epileptic cortex.

The expression of the gap-junction proteins connexin (CX) 43 and 32 was evaluated in surgical specimens of brain tumors and perilesional cortex from patients with chronic medically intractable epilepsy. In human normal brain CX32 was expressed in neurons and oligodendrocytes. CX32 immunoreactivity (IR) was observed in the neuronal component of glioneuronal tumors and in all oligodendrogliomas, 50% of which showed strong labeling, independent of the grade of differentiation. CX43, normally expressed in astrocytes, was also detected in most of the human astrocytomas and in the astroglial component of glioneuronal tumors. Whereas most of the low-grade gliomas (>60%) showed strong membranous staining, most high-grade astrocytomas exhibited a reduction of the typical plasma membrane CX43-IR and intracytoplasmic localization. Immunoblot analysis showed different CX43 isoforms in control cortex and in low-grade gliomas. However, only one single isoform (corresponding to the non-phosphorylated form of CX43) appeared to be present in most high-grade gliomas. Increased expression of CX43 protein was present in reactive astrocytes in the epileptic cortex surrounding low-grade tumors as compared to control cortex, indicating the existence of a regulatory pathway involving CX43 in the reorganization of the astrocytic syncytium in regions undergoing reactive gliosis. The high expression of connexin proteins in low-grade tumors and in the peritumoral reactive astrocytes suggests that they could contribute to tumor-related seizures.

Expression of brain-derived neurotrophic factor and tyrosine kinase B receptor proteins in glioneuronal tumors from patients with intractable epilepsy: colocalization with N-methyl-D-aspartic acid receptor.

Recent evidence suggests that brain-derived neurotrophic factor (BDNF) and its tyrosine kinase B (TrkB) receptor, in addition to promoting neuronal survival and differentiation, modulates synaptic transmission by increasing N-methyl-D-aspartic acid receptor (NMDAR) activity. Overexpression of BDNF may, then, interfere with normal brain function, causing increased excitability. We have examined the immunohistochemical expression of BDNF, full-length TrkB receptor and the NMDAR subunit 1 and subunit 2A/B proteins (NMDAR1 and NMDAR2A/B) in glioneuronal tumors (gangliogliomas, GG, n = 40; dysembryoplastic neuroepithelial tumors, DNT, n = 15), from patients with chronic intractable epilepsy. The great majority of tumors studied were positive for all markers examined, supporting the high level of neurochemical differentiation of these lesions. BDNF and TrkB immunoreactivity (ir) was mainly observed in the neuronal component of the tumors. In GG, more than 90% of tumors contained very intense BDNF-ir ganglion cells. Double labeling confirmed the presence of BDNF-ir and TrkB-ir in neurons which contained NMDAR1. NMDAR2A/B intensely labeled abnormal neurons in both GG and DNT and co-localized with NMDAR1. The presence of BDNF and its receptor in the neuronal component of GG and DNT may suggest a role for this neurotrophin in the development of these lesions, preventing the death of abnormal neuronal cells. In addition, since these neurons contain both NMDAR1 and NMDAR2A/B subunits, the BDNF-TrkB pathway may also contribute through a modulation of glutamatergic transmission to the intrinsic epileptogenicity of glioneuronal tumors.