Fatal spontaneous thrombosis of a cerebral arteriovenous malformation in a young patient with a rare heterozygousprothrombingene mutation

The authors report a case of fatal stroke due to thrombosis of a cerebral arteriovenous malformation (AVM) in a young patient. The patient presented with a progressive severe headache that had lasted for a few days, followed by a rapid deterioration in the level of consciousness. Computed tomography and magnetic resonance imaging were immediately performed, and the images showed a large area of venous ischemia in the left hemisphere as well as a left temporal pial AVM. An emergency decompressive craniectomy was unsuccessful in preventing deterioration in the patient's condition. An autopsy examination revealed a thrombosed AVM leading to a wide area of venous ischemia and massive brain swelling. Thrombophilia investigations identified a heterozygous mutation at position 20209 of the prothrombin gene, a recently reported rare prothrombotic defect. Acute neurological decline after spontaneous thrombosis of an intracranial AVM is rare, and an association with the prothrombin defect in this patient is likely.

Subtypes of oligodendroglioma defined by 1p,19q deletions, differ in the proportion of apoptotic cells but not in replication-licensed non-proliferating cells

Oligodendrogliomas may be divided into those with deletion of chromosomes 1p and 19q (Del+), and those without (Del−). Del+ tumours show better survival and chemoresponsiveness but the reason for this difference is unknown. We have investigated whether these subgroups differ in (a) apoptotic index, (b) the proportion of cells licensed for DNA replication but not in-cycle, and (c) the relative length of G₁-phase. Fluorescence in situ hybridisation with probes to 1p and 19q was used to determine the deletion status of 54 oligodendrogliomas, including WHO grades II and III. The apoptotic index was determined using counts of apoptotic bodies. Replication-licensed non-proliferating cells were determined from the Mcm2 minus Ki67 labelling index, whilst the geminin to Ki67 ratio was used as a measure of the relative length of G₁. Del+ oligodendrogliomas showed a higher apoptotic index than Del− tumours (P = 0.037); this was not accounted for by differences in tumour grade or in proliferation. There were no differences in the Mcm2 − Ki67 index or in the geminin/Ki67 ratio between the subgroups, but grade III tumours showed a higher proportion of licensed non-proliferating cells than grade II tumours (P = 0.001). An increased susceptibility to apoptosis in oligodendrogliomas with 1p ± 19q deletion may be important in their improved clinical outcome compared to Del− tumours.

Myopathy associated with gluten sensitivity

Ataxia and peripheral neuropathy are the most common neurological manifestations of gluten sensitivity. Myopathy is a less common and poorly characterized additional neurological manifestation of gluten sensitivity. We present our experience with 13 patients who presented with symptoms and signs suggestive of a myopathy and in whom investigation led to the diagnosis of gluten sensitivity. Three of these patients had a neuropathy with or without ataxia in addition to the myopathy. The mean age at onset of the myopathic symptoms was 54 years. Ten patients had neurophysiological evidence of myopathy. Inflammatory myopathy was the most common finding on neuropathological examination. One patient had basophilic rimmed vacuoles suggestive of inclusion-body myositis. Six patients received immunosuppressive treatment in addition to starting on a gluten-free diet; five improved and one remained unchanged. Among seven patients not on immunosuppressive treatment, four showed clinical improvement of the myopathy with a gluten-free diet. The improvement was also associated with reduction or normalization of serum creatine kinase level. The myopathy progressed in one patient who refused the gluten-free diet. Myopathy may be another manifestation of gluten sensitivity and is likely to have an immune-mediated pathogenesis. A gluten-free diet may be a useful therapeutic intervention.

Neuropathy associated with gluten sensitivity

OBJECTIVES

To prospectively study the clinical, neurophysiological and neuropathological characteristics of axonal neuropathies associated with positive antigliadin antibodies and the prevalence of such neuropathies in a cohort of patients with sporadic axonal neuropathy.

METHODS

Prospective screening (using antigliadin, antiendomysium and tissue transglutaminase antibodies) of patients with peripheral neuropathy attending a neurology clinic.

RESULTS

215 patients with axonal neuropathy were screened. 141 patients had symmetrical sensorimotor neuropathy, 47 had mononeuropathy multiplex, 17 had motor neuropathy and 10 had small-fibre neuropathy. Despite extensive investigations of the 215 patients, 140 had idiopathic neuropathy. Positive immunoglobulin (Ig)G with or without IgA antigliadin antibodies was found in 34% (47/140) of the patients with idiopathic neuropathy. This compares with 12% prevalence of these antibodies in the healthy controls. The prevalence of coeliac disease as shown by biopsy in the idiopathic group was at least 9% as compared with 1% in the controls. The clinical features of 100 patients (47 from the prevalence study and 53 referred from elsewhere) with gluten neuropathy included a mean age at onset of 55 (range 24-77) years and a mean duration of neuropathy of 9 (range 1-33) years. Gluten-sensitive enteropathy was present in 29% of patients. The human leucocyte antigen types associated with coeliac disease were found in 80% of patients.

CONCLUSIONS

Gluten sensitivity may be aetiologically linked to a substantial number of idiopathic axonal neuropathies.

White Matter Lesions in an Unselected Cohort of the Elderly

Background and Purpose— “Incidental” MRI white matter (WM) lesions, comprising periventricular lesions (PVLs) and deep subcortical lesions (DSCLs), are common in the aging brain. Direct evidence of ischemia associated with incidental WM lesions (WMLs) has been lacking, and their pathogenesis is unresolved.

Methods— A population-based, postmortem cohort (n=456) of donated brains was examined by MRI and pathology. In a subsample of the whole cohort, magnetic resonance images were used to sample and compare WMLs and nonlesional WM for molecular markers of hypoxic injury.

Results— PVL severity was associated with loss of ventricular ependyma ( P =0.004). For DSCLs, there was arteriolar sclerosis compared with normal WM (vessel wall thickness and perivascular enlargement; both P <0.001). Capillary endothelial activation (ratio of intercellular adhesion molecule to basement membrane collagen IV; P <0.001) and microglial activation (CD68 expression; P =0.002) were elevated in WMLs. Immunoreactivity for hypoxia-inducible factors (HIFs) HIF1α and HIF2α was elevated in DSCLs ( P =0.003 and P =0.005). Other hypoxia-regulated proteins were also increased in WMLs: matrix metalloproteinase-7 (PVLs P <0.001; DSCLs P =0.009) and the number of neuroglobin-positive cells (WMLs P =0.02) reaching statistical significance. The severity of congophilic amyloid angiopathy was associated with increased HIF1α expression in DSCLs ( P =0.04).

Conclusion— The data support a hypoxic environment within MRI WMLs. Persistent HIF expression may result from failure of normal adaptive mechanisms. WM ischemia appears to be a common feature of the aging brain.

Expression of Vascular Endothelial Growth Factor and Its Receptors in the Central Nervous System in Amyotrophic Lateral Sclerosis

Vascular endothelial growth factor (VEGF) prolongs survival in the mutant SOD1 transgenic mouse model of amyotrophic lateral sclerosis (ALS), whereas dysregulation of VEGF through deletion of its hypoxia-regulatory element causes motor neuron degeneration in mice. We investigated the expression of VEGF and its major agonist receptors in the normal central nervous system and in patients with ALS. Immunohistochemistry demonstrated similar expression patterns of VEGF and VEGF receptor 2 (VEGFR2) in the spinal cord with finely punctate staining of the neuropil and strong expression in anterior horn cells (AHCs). Granular staining on the surface of some AHCs, similar to that seen with synaptic markers, suggested synaptic labeling. VEGFR2 staining was reduced in the neuropil of ALS cases (p=0.018) associated with a reduction of synaptophysin but not SNAP25 expression. A greater proportion of AHCs in ALS cases showed low expression of VEGF (p=0.006) and VEGFR2 (p=0.009) compared with controls. Expression of VEGF and VEGFR2 was confirmed by Western blotting and quantitative reverse transcriptase-polymerase chain reaction (QPCR). The similar expression patterns of VEGF and VEGFR2 suggests autocrine/paracrine effects on spinal motor neurons, and the reduction in their expression seen in ALS cases would support the hypothesis that, as in mouse models of the disease, reduced VEGF signaling may play a role in the pathogenesis of ALS.

Production of monocyte chemoattractant protein-1 in amyotrophic lateral sclerosis

The presence of activated microglia in the spinal cord of amyotrophic lateral sclerosis (ALS) patients is usually accompanied by inflammatory biochemical changes, but these are largely unexplored. Monocyte chemoattractant protein-1 (MCP-1) is critical for recruitment of inflammatory cells of monocytic lineage after inflammation or injury to the central nervous system. MCP-1 concentrations were measured by an enzyme-linked immunosorbent assay in the cerebrospinal fluid (CSF) and the serum of 27 patients with ALS and 30 patients with noninflammatory neurological diseases. In ALS, circulating MCP-1 levels were significantly increased in the serum and particularly in the CSF. Immunoreactivity for MCP-1 in ALS spinal cord was detected mostly in astrocytes but also in microglia, neurons, and within the vasculature of the cord. Our findings suggest a role for MCP-1 as an important molecular mediator of the injury response in ALS.

Expression of Ki67, PCNA and the chromosome replication licensing protein Mcm2 in glial cells of the ageing human hippocampus increases with the burden of Alzheimer-type pathology

Cell-cycle mechanisms may be aberrantly reactivated in the ageing brain and associated with the development of pathology, including Alzheimer's disease. Activation of cell-cycle mechanisms in glia has, however, been little studied. Our aim was to determine whether expression of a marker for chromosomal replication licensing, Mcm2, occurs in glia of the ageing hippocampus, and to compare its expression to that of Ki67 and PCNA. Blocks of hippocampus were obtained from 19 elderly brains derived from the MRC-CFAS neuropathology cohort, which included a spectrum of Alzheimer-type pathology, semi-quantified using the Braak scoring system for neurofibrillary tangles. Mcm2, PCNA and Ki67 were detected immunohistochemically. Expression of Mcm2, Ki67 and PCNA was observed in glial cells and neurons, with a trend to increased expression in association with higher burdens of Alzheimer-type pathology. Mcm2 expression in glial cells showed a significant linear trend across Braak stages (P = 0.043). This study demonstrates that grey and white matter glial cells show expression of cell-cycle markers in the ageing brain and that re-licensing for chromosomal replication is a component of the mechanisms activated. A quantitative relationship to the burden of Alzheimer-type pathology suggests that cell-cycle re-entry in glial cells may be important in the pathogenesis of age-related neurodegeneration.

Progressive Loss of Motor Neuron Function in Wasted Mice: Effects of a Spontaneous Null Mutation in the Gene for the eEF1A2 Translation Factor

Wasted (wst) is a spontaneous autosomal recessive mutation in which the gene encoding translation factor eEF1A2 is deleted. Homozygous mice show tremors and disturbances of gait shortly after weaning, followed by motor neuron degeneration, paralysis, and death by about 28 days. We have now conducted a more detailed analysis of neuromuscular pathology in these animals. Reactive gliosis was observed at 19 days postnatal in wst/wst cervical spinal cord, showing a rostrocaudal gradient. This was followed a few days later by motor neuron vacuolation and neurofilament accumulation, again with a rostrocaudal progression. Thoracic/abdominal muscles from wst/wst mice aged 17 days showed evidence of progressive denervation of motor endplates, including weak synaptic transmission and retraction of motor nerve terminals. Similar abnormalities appeared in distal, lumbrical muscles from about 25 days of age. We conclude that spontaneous failure of eEF1A2 expression in the wasted mutant first triggers gliosis in spinal cord and retraction of motor nerve terminals in muscle, and then motor neuron pathology and death. The early initiation and rapid progression of motor unit degeneration in wst/wst mice suggest that they should be considered an important and accessible model of early-onset motor neuron degeneration in humans.

Discovery of a perinecrotic 60 kDa MDM2 isoform within glioma spheroids and glioblastoma biopsy material

Necrosis in glioblastoma is often associated with high levels of Fas (APO-1), HIF-1alpha and PARP expression. The presence of such molecules suggests a regulative element to cell death within this tissue, which may involve p53. We aimed to establish whether p53 and its downstream targets Bax, MDM2 and p21 play a role in perinecrotic cell death in glioblastoma. Following sequencing of the p53 gene in U87 and U373 glioma cell lines, p53 was found to be reactive in the p53 wild-type line U87 in response to hypoxia but not in the p53 mutant line, U373. Although no increase in perinecrotic p53 expression was detected in spheroid cultures derived from these lines, a 60 kDa MDM2 isoform lacking a C-terminal domain showed perinecrotic localization, irrespective of p53 status. Similar findings were observed surrounding regions of necrosis in 80% of glioblastoma biopsies examined. Increasing levels of wild-type p53 did not affect cell death in U87 spheroid cultures but killed all U373 cells 3 days post transfection. Dominant negative p53 did not affect cell death in U373 and U87 spheroid cultures. Although p53 accumulation appeared not to be important for the onset of cell death both in spheroid and biopsy cases, high levels of perinecrotic 60 kDa MDM2 may have implications for glioma cell death susceptibility in both p53 mutant and wild-type tumour cell populations.

A robust assay for alternative lengthening of telomeres in tumors shows the significance of alternative lengthening of telomeres in sarcomas and astrocytomas

PURPOSE AND EXPERIMENTAL DESIGN

Telomeres of tumor cells may be maintained by telomerase or by alternative lengthening of telomeres (ALT). The standard ALT assay requires Southern analysis of high molecular weight genomic DNA. We aimed to establish and validate an ALT assay suitable for archived paraffin-embedded tumors and to use it to examine the prevalence and clinical significance of ALT in various types of tumors that are often telomerase negative.

RESULTS

To assay for ALT, we detected ALT-associated promyelocytic leukemia (PML) bodies (APBs) by combined PML immunofluorescence and telomere fluorescence in situ hybridization. APBs are PML nuclear domains containing telomeric DNA and are a known hallmark of ALT in cell lines. The APB assay concurred with the standard ALT assay in 62 of 62 tumors and showed that 35% of 101 soft tissue sarcomas (STS), 47% of 58 osteosarcomas (especially younger patients), 34% of 50 astrocytomas, and 0% of 17 papillary thyroid carcinomas were ALT positive (ALT+). The prevalence of ALT varied greatly among different STS subtypes: malignant fibrous histiocytomas, 77%; leiomyosarcomas, 62%; liposarcomas, 33%; synovial sarcomas, 9%; and rhabdomyosarcomas, 6%. ALT correlated with survival in glioblastoma multiforme and occurred more often in lower-grade astrocytomas, but ALT+ and ALT- sarcomas were equally aggressive in terms of grade and clinical outcome.

CONCLUSION

The APB assay for ALT is suitable for paraffin-embedded tumors. It showed that a substantial proportion of STS, osteosarcomas, and astrocytomas, but not papillary thyroid carcinomas use ALT. APB positivity correlated strongly with survival of patients with astrocytomas.

A Robust Assay for Alternative Lengthening of Telomeres in Tumors Shows the Significance of Alternative Lengthening of Telomeres in Sarcomas and Astrocytomas

Purpose and Experimental Design: Telomeres of tumor cells may be maintained by telomerase or by alternative lengthening of telomeres (ALT). The standard ALT assay requires Southern analysis of high molecular weight genomic DNA. We aimed to establish and validate an ALT assay suitable for archived paraffin-embedded tumors and to use it to examine the prevalence and clinical significance of ALT in various types of tumors that are often telomerase negative.

Results: To assay for ALT, we detected ALT-associated promyelocytic leukemia (PML) bodies (APBs) by combined PML immunofluorescence and telomere fluorescence in situ hybridization. APBs are PML nuclear domains containing telomeric DNA and are a known hallmark of ALT in cell lines. The APB assay concurred with the standard ALT assay in 62 of 62 tumors and showed that 35% of 101 soft tissue sarcomas (STS), 47% of 58 osteosarcomas (especially younger patients), 34% of 50 astrocytomas, and 0% of 17 papillary thyroid carcinomas were ALT positive (ALT+). The prevalence of ALT varied greatly among different STS subtypes: malignant fibrous histiocytomas, 77%; leiomyosarcomas, 62%; liposarcomas, 33%; synovial sarcomas, 9%; and rhabdomyosarcomas, 6%. ALT correlated with survival in glioblastoma multiforme and occurred more often in lower-grade astrocytomas, but ALT+ and ALT− sarcomas were equally aggressive in terms of grade and clinical outcome.

Conclusion: The APB assay for ALT is suitable for paraffin-embedded tumors. It showed that a substantial proportion of STS, osteosarcomas, and astrocytomas, but not papillary thyroid carcinomas use ALT. APB positivity correlated strongly with survival of patients with astrocytomas.

DNA replication licensing and cell cycle kinetics of oligodendroglial tumours

The convergence point of growth-signalling pathways that control cell proliferation is the initiation of genome replication, the core of which is the assembly of pre-replicative complexes (pre-RCs), resulting in chromatin being ‘licensed’ for DNA replication in the subsequent S phase. The Mcm2–7 complex is a core constituent of the pre-RC, whose recruitment to replication origins is dependent on the Cdt1 loading factor. Geminin is a potent inhibitor of the initiation of DNA replication by preventing Mcm2–7 assembly at origins via its interaction with Cdt1, ensuring genomic integrity through suppression of re-initiation events in S phase. Here we investigate the regulation of Ki67, Mcm2, p21, caspase 3 and Geminin in a series of 55 oligodendrogliomas to provide an integrated picture of how cellular proliferation and programmed cell death are dysregulated in these tumours. Geminin does not behave as an inhibitor of cell proliferation, its labelling index rising with increasing growth fraction as defined by Ki67 or Mcm2 expression. Geminin is expressed in a higher proportion of cells in higher grade tumours (P<0.001) and shows a strong correlation to proliferation and replication licensing (P<0.01), but not apoptosis. Increasing tumour anaplasia is not associated with loss of Geminin. Importantly, the G1 phase of the proliferative cell cycle, as assessed by the Geminin/Ki67 ratio, shortens with increasing anaplasia, providing new potential algorithms for prognostic assessment. Origin licensing proteins thus provide powerful novel tools for assessment of tumour cell cycle kinetics in routinely processed surgical biopsy material.

Hereditary spastic paraparesis: disrupted intracellular transport associated with spastin mutation

The commonest cause of hereditary spastic paraplegia (HSP) is mutation in the spastin gene. Both the normal function of spastin in the central nervous system and the mechanism by which mutation in spastin causes axonal degeneration are unknown. One hypothesis is that mutant spastin disrupts microtubule dynamics, causing an impairment of organelle transport on the microtubule network, which leads to degeneration in the distal parts of long axons. To study this neuronal and non-neuronal cells were transfected with either wild type or mutant spastin proteins. We demonstrated evidence of a transient interaction of wild-type spastin with microtubules, with resulting disassembly of microtubules, supporting a role for wild-type spastin as a microtubule-severing protein. Mutant spastin demonstrated an abnormal interaction with microtubules, colocalizing with but no longer severing microtubules. The abnormal interaction of mutant spastin with microtubules was demonstrated to be associated with an abnormal perinuclear clustering of mitochondria and peroxisomes, suggestive of an impairment of kinesin-mediated intracellular transport. Our findings indicate that an abnormal interaction of mutant spastin with microtubules, which disrupts organelle transport on the microtubule cytoskeleton, is likely to be the primary disease mechanism in HSP caused by missense mutations in the spastin gene.

The cellular and molecular pathology of the motor system in hereditary spastic paraparesis due to mutation of the spastin gene

Hereditary spastic paraparesis (HSP) is a genetically heterogeneous disorder, the most common cause of which is mutation of the spastin gene. Recent evidence suggests a role for spastin in microtubule dynamics, but the distribution of the protein within the CNS is unknown. The core neuropathology of HSP is distal degeneration of the lateral corticospinal tract and of fasciculus gracilis, but there are few neuropathological studies of cases with a defined mutation. We aimed to determine the distribution of spastin expression in the human CNS and to investigate the cellular pathology of the motor system in HSP due to mutation of the spastin gene. Using an antibody to spastin, we have carried out immunohistochemistry on postmortem brain. We have demonstrated that spastin is a neuronal protein. It is widely expressed in the CNS so that the selectivity of the degeneration in HSP is not due to the normal cellular distribution of the protein. We have identified mutation of the spastin gene in 3 autopsy cases of HSP. Distal degeneration of long tracts in the spinal cord, consistent with a dying back axonopathy, was accompanied by a microglial reaction. The presence of novel hyaline inclusions in anterior horn cells and an alteration in immunostaining for cytoskeletal proteins and mitochondria indicates that long tract degeneration is accompanied by cytopathology in the motor system and may support a role for derangement of cytoskeletal function. All 3 cases also demonstrated evidence of tau pathology outside the motor system, suggesting that the neuropathology is not confined to the motor system in spastin-related HSP.

Morphological changes and stress responses in neurons in cerebral cortex infiltrated by diffuse astrocytoma

Local dysfunction in cerebral cortex infiltrated by astrocytoma can cause epilepsy and focal neurological deficits, but the cellular pathology of peritumoral cortex remains poorly defined. The aims of the present study were to define the morphological changes which occur in neurons in tumor-infiltrated cerebral cortex, and to determine whether peritumoral neurons show expression of cell stress-related proteins. Archival specimens of diffuse astrocytoma (n = 28) were identified with areas of both tumor-infiltrated cortex and apparently non-infiltrated cortex. Immunohistochemistry was performed to structural neuronal proteins (MAP-2, neurofilament proteins), beta-amyloid precursor protein, growth associated protein-43 and to injury response proteins (poly(ADP-ribose) polymerase, poly(ADP-ribose), c-fos, and c-jun). Tumor-infiltrated cortex revealed neuronal loss and architectural disarray compared to non-infiltrated cortex. Pyramidal neurons showed thinning of the cytoplasmic rim and their neuritic processes showed increasing tortuosity, varicosity, fragmentation and loss, with axonal spheroid formation and dendritic beading. Poly(ADP-ribose) polymerase, poly(ADP-ribose) and c-fos were up-regulated in both infiltrated and non-infiltrated cortex, but c-jun expression was greater in areas of tumor-infiltrated cortex. Surviving neurons in cortex infiltrated by astrocytoma demonstrate, therefore, a sequence of morphological alterations in their dendritic, somatic and axonal compartments, and demonstrate a cell stress response. The patterns of cellular pathology identified suggest possible mechanisms, by which neurons are damaged and eventually lost in peritumoral brain.

Comparative genomic hybridization and pathological findings in atypical teratoid/rhabdoid tumour of the central nervous system

The atypical teratoid/rhabdoid tumour (AT/RT) is an uncommon tumour of the central nervous system in children, characterized by the presence of a rhabdoid cell component associated with variable combinations of primitive neuroectodermal tumour, mesenchymal and epithelial differentiation. Immunohistochemistry reveals a complex pattern of antigen expression and cytogenetic studies have demonstrated losses from chromosome 22. We have performed comparative genomic hybridization (CGH) on paraffin-embedded material from three cases of AT/RT. Two cases showed losses from chromosome 22 associated with other chromosome imbalances including losses from 1p in both cases. The third case demonstrated a loss from 8p as the sole abnormality. While monosomy or deletion from chromosome 22 is a useful diagnostic marker for AT/RT, it is not present in all cases. The variation in cytogenetic patterns reported for this tumour type raises the possibility that different genetic pathways may underlie this tumour phenotype and warrants the further definition of the cytogenetic spectrum for this rare tumour.

Corticospinal tract degeneration in the progressive muscular atrophy variant of ALS

OBJECTIVE

Examining the unresolved relationship between the lower motor neuron disorder progressive muscular atrophy (PMA) and ALS is important in clinical practice because of emerging therapies.

METHODS

Spinal and brainstem tissues donated from patients with ALS/motor neuron disorder (n = 81) were examined. Using retrospective case note review, the authors assigned patients into three categories: PMA (12), PMA progressing to ALS (6), and ALS ab initio (63). Conventional stains for long tract degeneration and immunocytochemistry for ubiquitin and the macrophage marker CD68 were examined.

RESULTS

Rapid progression and typical ubiquitinated inclusions in lower motor neurons were present in 77 (95%) of the cases. Immunocytochemistry for CD68 was a more sensitive marker of long tract pathology in comparison with conventional stains. Half of the cases with PMA showed corticospinal tract degeneration by CD68.

CONCLUSION

Patients with PMA frequently have undetected long tract pathology and most have ubiquitinated inclusions typical of ALS. A patient presenting with PMA with rapid clinical evolution likely has the pathology and pathophysiology of ALS whether or not upper motor neuron signs evolve.

Proliferation and death of conditionally immortalized neural cells from murine neocortex: p53 alters the ability of neuron-like cells to re-enter the cell cycle

Neurons are distinctive in that they are generally considered to be permanently post-mitotic cells. The oncoprotein p53 is a key regulator in neuronal development, notably in cell proliferation and neuronal death. We hypothesize that p53 maintains the post-mitotic characteristic of differentiated neurons. New lines of conditionally immortalized cortical cells were generated to test this hypothesis. Populations of cells were obtained from the neocortices of dual transgenic mice that were null for p53 and expressed a temperature-sensitive SV40 large T antigen. At a permissive temperature (32 degrees C), the cells continued to proliferate and most expressed nestin and proteins associated with glia. At a non-permissive temperature (39 degrees C), the cells expressed cytoskeletal proteins associated with differentiated neurons such as microtubule associated protein 2 and neurofilament 200. Under permissive conditions, both p53(+/-) and p53(-/-) cells exhibited similar cycling behaviors; the length of the cell cycle was 13-15 h and >85% of the cells were actively cycling. In non-permissive conditions, most p53(+/-) cells stopped dividing, whereas the p53(-/-) cells continued to proliferate. The survival of the cells also differed. In the non-permissive conditions, many p53(+/-) cells died following treatment with a neurotoxin (ethanol, 400 mg/dl), whereas the p53(-/-) cells did not. After re-introduction to the permissive conditions, both cell lines expressed neuron-like characteristics, but only the p53(-/-) cells retained their ability to cycle. Therefore, p53-mediated activities appear to be involved in the proliferation, survival, and post-mitotic nature of neuron-like cells.

Glioma tumourgenicity is decreased by iNOS knockout: experimental studies using the C6 striatal implantation glioma model

Nitric oxide synthase (NOS) has recently been shown to be an important pathophysiological regulator in experimental implantation glioma since manipulation of NOS can significantly alter tumoural blood flow and inhibit tumour growth. In this study we investigated the role of iNOS (inducible NOS) in glioma tumourogenisis using the rodent C6 striatal implantation model. We produced genetically engineered C6 clones that do not express iNOS activity even after stimulation with a mixture of lipopolysaccaride (LPS) and tumour necrosis factor (TNF)-alpha. These iNOS knockout cells showed a similar growth rate to control cells in vivo at 5 days. We then performed an in vivo implantation glioma study using either the iNOS knockout clone or two genetically engineered control C6 clones. There was a significant reduction (p < 0.01) of tumour mass with the iNOS knockout clone 28 days after the implantation. Immunocytochemistry indicated infiltrates of CD3 positive T cells and macrophages in the controls and the iNOS knockout group. These studies indicate that iNOS expression by tumour parenchymal cells is a critical factor for tumour growth with this model. The mechanisms that cause failure of tumour growth need clarification prior to considering that specific iNOS inhibitors might be candidates for adjuvant treatment of malignant glioma.

Highly unsaturated fatty acid induced tumour regression in glioma pharmacodynamics and bioavailability of gamma linolenic acid in an implantation glioma model: effects on tumour biomass, apoptosis and neuronal tissue histology

Highly unsaturated fatty acids (HUFAs) are naturally occurring anti-tumour agents. HUFAs act as intracellular signalling molecules in cell proliferation and death. In human glioma, HUFAs may stimulate tumour regression and apoptosis. An implantation glioma model, using the C6 glioma cell line, was used to investigate the bioactivity of locally infused n-6 HUFA gamma linolenic acid (GLA). Rat brains (15 normal and 37 C6 tumour bearing) were infused with vehicle or GLA 200 microM-2 mM. The most active local concentration of GLA for anti-tumour activity was 2 mM, infused at 1 microl/h over 7 days. Tumour regression, increased apoptosis and decreased proliferation were observed in tumours of rats infused with this concentration of GLA. Little effect on normal neuronal tissue was detected. The intraparenchymal route was an effective method of GLA administration in the treatment of glioma. These studies provide further insights into the potential role of HUFAs as anti-glioma agents.