Granulocyte-colony stimulating factor for mobilizing bone marrow stem cells in subacute stroke: the stem cell trial of recovery enhancement after stroke 2 randomized controlled trial

BACKGROUND AND PURPOSE

Granulocyte-colony stimulating factor (G-CSF) is neuroprotective in experimental stroke and mobilizes CD34(+) peripheral blood stem cells into the circulation. We assessed the safety of G-CSF in recent stroke in a phase IIb single-center randomized, controlled trial.

METHODS

G-CSF (10 μg/kg) or placebo (ratio 2:1) was given SC for 5 days to 60 patients 3 to 30 days after ischemic or hemorrhagic stroke. The primary outcome was the frequency of serious adverse events. Peripheral blood counts, CD34(+) count, and functional outcome were measured. MRI assessed lesion volume, atrophy, and the presence of iron-labeled CD34(+) cells reinjected on day 6.

RESULTS

Sixty patients were recruited at mean of 8 days (SD ± 5) post ictus, with mean age 71 years (± 12 years) and 53% men. The groups were well matched for baseline minimization/prognostic factors. There were no significant differences between groups in the number of participants with serious adverse events: G-CSF 15 (37.5%) of 40 versus placebo 7 (35%) of 20, death or dependency (modified Rankin Score: G-CSF 3.3 ± 1.3, placebo 3.0 ± 1.3) at 90 days, or the number of injections received. G-CSF increased CD34(+) and total white cell counts of 9.5- and 4.2-fold, respectively. There was a trend toward reduction in MRI ischemic lesion volume with respect to change from baseline in G-CSF-treated patients (P=0.06). In 1 participant, there was suggestion that labeled CD34(+) cells had migrated to the ischemic lesion.

CONCLUSIONS

This randomized, double-blind, placebo-controlled trial suggests that G-CSF is safe when administered subacutely. It is feasible to label and readminister iron-labeled CD34(+) cells in patients with ischemic stroke.

CLINICAL TRIAL REGISTRATION

URL: www.controlled-trials.com. Unique identifier: ISRCTN63336619.

Genome-wide molecular characterization of central nervous system primitive neuroectodermal tumor and pineoblastoma

Central nervous system primitive neuroectodermal tumor (CNS PNET) and pineoblastoma are highly malignant embryonal brain tumors with poor prognoses. Current therapies are based on the treatment of pediatric medulloblastoma, even though these tumors are distinct at both the anatomical and molecular level. CNS PNET and pineoblastoma have a worse clinical outcome than medulloblastoma; thus, improved therapies based on an understanding of the underlying biology of CNS PNET and pineoblastoma are needed. To this end, we characterized the genomic alterations of 36 pediatric CNS PNETs and 8 pineoblastomas using Affymetrix single nucleotide polymorphism arrays. Overall, the majority of CNS PNETs contained a greater degree of genomic imbalance than pineoblastomas, with gain of 19p (8 [27.6%] of 29), 2p (7 [24.1%] of 29), and 1q (6 [20.7%] of 29) common events in primary CNS PNETs. Novel gene copy number alterations were identified and corroborated by Genomic Identification of Significant Targets In Cancer (GISTIC) analysis: gain of PCDHGA3, 5q31.3 in 62.1% of primary CNS PNETs and all primary pineoblastomas and FAM129A, 1q25 in 55.2% of primary CNS PNETs and 50% of primary pineoblastomas. Comparison of our GISTIC data with publically available data for medulloblastoma confirmed these CNS PNET-specific copy number alterations. With use of the collection of 5 primary and recurrent CNS PNET pairs, we found that gain of 2p21 was maintained at relapse in 80% of cases. Novel gene copy number losses included OR4C12, 11p11.12 in 48.2% of primary CNS PNETs and 50% of primary pineoblastomas. Loss of CDKN2A/B (9p21.3) was identified in 14% of primary CNS PNETs and was significantly associated with older age among children (P = .05). CADPS, 3p14.2 was lost in 27.6% of primary CNS PNETs and was associated with poor prognosis (P = .043). This genome-wide analysis revealed the marked molecular heterogeneity of CNS PNETs and enabled the identification of novel genes and clinical associations potentially involved in the pathogenesis of these tumors.

Histological and confocal microscopy changes in chronic corneal edema: implications for endothelial transplantation

PURPOSE

To report in vivo confocal microscopic (IVCM) features in corneal edema supported by histopathologic correlation.

METHODS

This was an observational study with evaluation of diagnostic technology. Twenty patients with clinically diagnosed corneal edema were involved, including 11 with Fuchs' endothelial dystrophy (FED). All cases, in addition to a control group of six normal eyes, were examined with IVCM before keratoplasty. Four eyes were examined after surgery. Thirteen corneal samples obtained by penetrating keratoplasty were examined by light and/or electron microscopy. IVCM and histopathologic sections were then analyzed for correlation and proper interpretation. Seven patients underwent Descemet's stripping endothelial keratoplasty (DSEK).

RESULTS

Subepithelial fibroblasts were seen histologically and with IVCM in 7 (53.8%) of 13 full-thickness corneal samples. IVCM alone detected these changes in 11 (55%) subjects before surgery, as well as after postoperative clinical improvement. Other IVCM features included absent (30%) or reduced (70%) subbasal corneal nerves, expanded hyperreflective keratocyte cell bodies, and processes with small vacuoles and large extracellular lacunae (95%), seen on IVCM only. Endothelial changes with polymegathism and reduced cell density were seen in non-FED cases.

CONCLUSIONS

This is the first study in which IVCM features of corneal edema have been compared in detail with histopathologic findings. Subepithelial fibroblasts, reduced subbasal corneal nerves, and stromal keratocyte morphology were well documented in this study. With increasing popularity of DSEK this work supports the role of IVCM in quantitative evaluation of corneal edema in early preoperative stages, as well as after surgery, when the cornea appear clinically, but not histologically, normal.

Corneal nerve aberrations in bullous keratopathy

PURPOSE

To study the corneal nerves in patients with chronic bullous keratopathy.

DESIGN

Prospective observational case series with histologic evaluation.

METHODS

We studied 25 eyes of 25 bullous keratopathy patients of different etiologies (17 female, 8 male; mean age, 76.3 years) as well as 6 eyes of 6 normal control subjects (5 male, 1 female; mean age, 38 years). All subjects were scanned by laser scanning confocal microscope. Five corneal buttons obtained following penetrating keratoplasty from 5 of the above patients and 6 normal control corneal buttons were stained as whole mounts with acetylcholinesterase (AChE) method for corneal nerve demonstration and scanned in multiple layers with digital pathology scanning microscope.

RESULTS

The density, branching pattern, and diameter of sub-basal nerves were significantly lower in corneas with bullous keratopathy compared with normal corneas (density: 4.42 ± 1.91 mm/mm(2) vs 20.05 ± 4.24 mm/mm(2); branching pattern: 36.02% ± 26.57% vs 70.79% ± 10.53%; diameter: 3.07 ± 0.64 μm vs 4.57 ± 1.12 μm). Aberrations such as localized thickenings or excrescences, abnormal twisting, coiling, and looping of the (mid) stromal nerves were observed in the study group both by in vivo confocal microscopy and on histology.

CONCLUSIONS

Striking alterations in corneal innervation are present in corneas with bullous keratopathy that are unrelated to any specific etiology of bullous keratopathy. This study provides histologic confirmation of novel in vivo confocal microscopy findings related to corneal nerves in bullous keratopathy.

Corneal intraepithelial neoplasia: in vivo confocal microscopic study with histopathologic correlation

PURPOSE

To ascertain in vivo confocal microscopic features of corneal/conjunctival intraepithelial neoplasia (CIN) and correlate these with histology of the same lesions.

DESIGN

Observational case series with evaluation of diagnostic technology.

METHODS

Four patients with unilateral CIN (3 men and 1 woman) were examined with the Heidelberg Retina Tomograph II (HRT II) Rostock Cornea Module (RCM) confocal microscope before, during, and after treatment. Corneal epithelial samples were taken by alcohol delamination technique in 2 patients, while impression cytology (IC) samples were obtained in the other 2 patients. Morphometric analysis of confocal and histologic images was carried out and the findings correlated. Four controls (all men, 2 with limbal stem cell deficiency, 1 with a limbal lesion, and 1 with diffuse keratoconjunctival proliferation) were similarly examined. Two of these had biopsy for histologic examination. Main outcome measures comprised the degree of correlation between histology and confocal microscopic features of CIN.

RESULTS

Dysplastic cellular changes were noticed on histopathology and correlated well with confocal microscopy, corresponding to the different corneal epithelial layers. Bright nucleoli within huge nuclei and ill-defined cell borders were a feature of the basal epithelium on histopathology and confocal microscopy. Subbasal corneal nerves were not visualized on confocal microscopy in areas affected by CIN. These features disappeared in response to treatment cycles as the basal epithelium reverted to its normal pattern, as seen by confocal microscopy.

CONCLUSION

Confocal microscopy findings highly correlate with histologic features in CIN. Confocal microscopic features of CIN as defined in this study will enable a reliable diagnosis in a noninvasive manner. Confocal microscopy will also allow real-time monitoring of the condition during treatment.

Duplication of amyloid precursor protein (APP), but not prion protein (PRNP) gene is a significant cause of early onset dementia in a large UK series

Amyloid precursor protein gene (APP) duplications have been identified in screens of selected probands with early onset familial Alzheimer's disease (FAD). A causal role for copy number variation (CNV) in the prion protein gene (PRNP) in prion dementias is not known. We aimed to determine the prevalence of copy number variation in APP and PRNP in a large referral series, test a screening method for detection of the same, and expand knowledge of clinical phenotype. We used a 3-tiered screening assay for APP and PRNP duplication (exonic real-time quantitative polymerase chain reaction [exon-qPCR], fluorescent microsatellite quantitative PCR [fm-q-PCR], and Illumina array [Illumina Inc., San Diego, CA, USA]) for analysis of a heterogeneous referral series comprising 1531 probands. Five of 1531 probands screened showed APP duplication, a similar prevalence to APP missense mutation. Real-time quantitative PCR and fluorescent microsatellite quantitative PCR were similar individually but are theoretically complementary; we used Illumina arrays as our reference assay. Two of 5 probands were from an autosomal dominant early onset Alzheimer's disease (familial Alzheimer's disease) pedigree. One extensive, noncontiguous duplication on chromosome 21 was consistent with an unbalanced translocation not including the Down's syndrome critical region. Seizures were prominent in the other typical APP duplications. A range of imaging, neuropsychological, cerebrospinal fluid, and pathological findings are reported that extend the known phenotype. APP but not PRNP duplication is a significant cause of early onset dementia in the UK. The recognized phenotype may be expanded to include the possibility of early seizures and apparently sporadic disease which, in part, may be due to different mutational mechanisms. The pros and cons of our screening method are discussed.

Ubiquitin-like protein conjugation and the ubiquitin-proteasome system as drug targets

Ubiquitin is a highly conserved 76 amino-acid protein that covalently attaches to protein substrates targeted for degradation by the 26S proteasome. The coordinated effort of a series of enzymes, including an activating enzyme (E1), a conjugating enzyme (E2) and a ligase (E3), uses ATP to ultimately form an isopeptide bond between ubiquitin and a substrate.

Another class of enzymes called deubiquitylating enzymes (DUBs) deconstruct these linkages and also have an essential role in ubiquitin function. In addition, ubiquitin-like proteins (UBLs), including NEDD8, SUMO and ISG15, share a characteristic three-dimensional fold with ubiquitin but have their own dedicated enzyme cascades and distinct (although sometimes overlapping) biological functions.

The ubiquitin–proteasome system (UPS) and UBL conjugation pathways have important roles in various human diseases, including numerous types of cancer, cardiovascular disease, viral diseases and neurodegenerative disorders. The proteasome inhibitor bortezomib (Velcade; Millennium Pharmaceuticals) is the first clinically validated drug to target the UPS and is approved for the treatment of multiple myeloma. This suggests that other diseases may conceivably be targeted by modulating components of the UPS and UBL conjugation pathways using small-molecule inhibitors.

A significant hurdle to identifying drug-like inhibitors of enzyme targets within the UPS and UBL conjugation pathways is the limited understanding of the molecular mechanisms and biological consequences of UBL conjugation.

Here, we provide an overview of the enzyme classes in the UPS and UBL pathways that are potential therapeutic targets, and highlight considerations that are important for drug discovery. We also discuss the progress in the development of small-molecule inhibitors, and review developments in understanding of the role of the components of the UPS and the UBL pathways in disease and their potential for therapeutic intervention.

The ubiquitin–proteasome system (UPS) and ubiquitin-like protein (UBL) conjugation pathways are integral to cellular protein homeostasis, and their functional importance in various diseases, including cancer, cardiovascular disease and neurodegenerative disorders, is now beginning to emerge. Brownell and colleagues review developments in understanding of the role of the components of the UPS and the UBL pathways in disease and their potential for therapeutic intervention.

The ubiquitin–proteasome system (UPS) and ubiquitin-like protein (UBL) conjugation pathways are integral to cellular protein homeostasis. The growing recognition of the fundamental importance of these pathways to normal cell function and in disease has prompted an in-depth search for small-molecule inhibitors that selectively block the function of these pathways. However, our limited understanding of the molecular mechanisms and biological consequences of UBL conjugation is a significant hurdle to identifying drug-like inhibitors of enzyme targets within these pathways. Here, we highlight recent advances in understanding the role of some of these enzymes and how these new insights may be the key to developing novel therapeutics for diseases including immuno-inflammatory disorders, cancer, infectious diseases, cardiovascular disease and neurodegenerative disorders.

Homozygous loss of ADAM3A revealed by genome-wide analysis of pediatric high-grade glioma and diffuse intrinsic pontine gliomas

Overall, pediatric high-grade glioma (pHGG) has a poor prognosis, in part due to the lack of understanding of the underlying biology. High-resolution 244 K oligo array comparative genomic hybridization (CGH) was used to analyze DNA from 38 formalin-fixed paraffin-embedded predominantly pretreatment pHGG samples, including 13 diffuse intrinsic pontine gliomas (DIPGs). The patterns of gains and losses were distinct from those seen in HGG arising in adults. In particular, we found 1q gain in up to 27% of our cohort compared with 9% reported in adults. A total of 13% had a balanced genetic profile with no large-scale copy number alterations. Homozygous loss at 8p12 was seen in 6 of 38 (16%) cases of pHGG. This novel deletion, which includes the ADAM3A gene, was confirmed by quantitative real-time PCR (qPCR). Loss of CDKN2A/CDKN2B in 4 of 38 (10%) samples by oligo array CGH was confirmed by fluorescent in situ hybridization on tissue microarrays and was restricted to supratentorial tumors. Only ∼50% of supratentorial tumors were positive for CDKN2B expression by immunohistochemistry (IHC), while ∼75% of infratentorial tumors were positive for CDKN2B expression (P = 0.03). Amplification of the 4q11-13 region was detected in 8% of cases and included PDGFRA and KIT, and subsequent qPCR analysis was consistent with the amplification of PDGFRA. MYCN amplification was seen in 5% of samples being significantly associated with anaplastic astrocytomas (P= 0.03). Overall, DIPG shared similar spectrum of changes to supratentorial HGG with some notable differences, including high-frequency loss of 17p and 14q and lack of CDKN2A/CDKN2B deletion. Informative genetic data providing insight into the underlying biology and potential therapeutic possibilities can be generated from archival tissue and typically small biopsies from DIPG. Our findings highlight the importance of obtaining pretreatment samples.

Pediatric brain tumor cancer stem cells: cell cycle dynamics, DNA repair, and etoposide extrusion

Reliable model systems are needed to elucidate the role cancer stem cells (CSCs) play in pediatric brain tumor drug resistance. The majority of studies to date have focused on clinically distinct adult tumors and restricted tumor types. Here, the CSC component of 7 newly established primary pediatric cell lines (2 ependymomas, 2 medulloblastomas, 2 gliomas, and a CNS primitive neuroectodermal tumor) was thoroughly characterized. Comparison of DNA copy number with the original corresponding tumor demonstrated that genomic changes present in the original tumor, typical of that particular tumor type, were retained in culture. In each case, the CSC component was approximately 3–4-fold enriched in neurosphere culture compared with monolayer culture, and a higher capacity for multilineage differentiation was observed for neurosphere-derived cells. DNA content profiles of neurosphere-derived cells expressing the CSC marker nestin demonstrated the presence of cells in all phases of the cell cycle, indicating that not all CSCs are quiescent. Furthermore, neurosphere-derived cells demonstrated an increased resistance to etoposide compared with monolayer-derived cells, having lower initial DNA damage, potentially due to a combination of increased drug extrusion by ATP-binding cassette multidrug transporters and enhanced rates of DNA repair. Finally, orthotopic xenograft models reflecting the tumor of origin were established from these cell lines. In summary, these cell lines and the approach taken provide a robust model system that can be used to develop our understanding of the biology of CSCs in pediatric brain tumors and other cancer types and to preclinically test therapeutic agents.

Juvenile ALS with basophilic inclusions is a FUS proteinopathy with FUS mutations

BACKGROUND

Juvenile amyotrophic lateral sclerosis (ALS) with basophilic inclusions is a form of ALS characterized by protein deposits in motor neurons that are morphologically and tinctorially distinct from those of classic sporadic ALS. The nosologic position of this type of ALS in the molecular pathologic and genetic classification of ALS is unknown.

METHODS

We identified neuropathologically 4 patients with juvenile ALS with basophilic inclusions and tested the hypothesis that specific RNA binding protein pathology may define this type of ALS. Immunohistochemical findings prompted us to sequence the fused in sarcoma (FUS) gene.

RESULTS

Motor symptoms began between ages 17 and 22. Disease progression was rapid without dementia. No family history was identified. Basophilic inclusions were strongly positive for FUS protein but negative for TAR DNA binding protein 43 (TDP-43). Granular and compact FUS deposits were identified in glia and neuronal cytoplasm and nuclei. Ultrastructure of aggregates was in keeping with origin from fragmented rough endoplasmic reticulum. Sequencing of all 15 exons of the FUS gene in 3 patients revealed a novel deletion mutation (c.1554_1557delACAG) in 1 individual and the c.1574C>T (P525L) mutation in 2 others.

CONCLUSION

Juvenile ALS with basophilic inclusions is a FUS proteinopathy and should be classified as ALS-FUS. The FUS c.1574C>T (P525L) and c.1554_1557delACAG mutations are associated with this distinct phenotype. The molecular genetic relationship with frontotemporal lobar degeneration with FUS pathology remains to be clarified.

Integrated molecular genetic profiling of pediatric high-grade gliomas reveals key differences with the adult disease

PURPOSE

To define copy number alterations and gene expression signatures underlying pediatric high-grade glioma (HGG).

PATIENTS AND METHODS

We conducted a high-resolution analysis of genomic imbalances in 78 de novo pediatric HGGs, including seven diffuse intrinsic pontine gliomas, and 10 HGGs arising in children who received cranial irradiation for a previous cancer using single nucleotide polymorphism microarray analysis. Gene expression was analyzed with gene expression microarrays for 53 tumors. Results were compared with publicly available data from adult tumors.

RESULTS

Significant differences in copy number alterations distinguish childhood and adult glioblastoma. PDGFRA was the predominant target of focal amplification in childhood HGG, including diffuse intrinsic pontine gliomas, and gene expression analyses supported an important role for deregulated PDGFRalpha signaling in pediatric HGG. No IDH1 hotspot mutations were found in pediatric tumors, highlighting molecular differences with adult secondary glioblastoma. Pediatric and adult glioblastomas were clearly distinguished by frequent gain of chromosome 1q (30% v 9%, respectively) and lower frequency of chromosome 7 gain (13% v 74%, respectively) and 10q loss (35% v 80%, respectively). PDGFRA amplification and 1q gain occurred at significantly higher frequency in irradiation-induced tumors, suggesting that these are initiating events in childhood gliomagenesis. A subset of pediatric HGGs showed minimal copy number changes.

CONCLUSION

Integrated molecular profiling showed substantial differences in the molecular features underlying pediatric and adult HGG, indicating that findings in adult tumors cannot be simply extrapolated to younger patients. PDGFRalpha may be a useful target for pediatric HGG, including diffuse pontine gliomas.

Architecture and distribution of human corneal nerves

AIMS

To comprehensively study the gross anatomy of human corneal innervation.

METHODS

Twenty-one specimens, including 12 normal human corneas from seven deceased patients, two eye-bank corneo-scleral buttons, two eye-bank corneo-scleral rims and five post-surgical specimens from three patients with keratoconus were studied. Corneal whole mounts were stained for cholinesterase enzyme using the Karnovsky & Roots direct colouring thiocholine modification of acetylcholinesterase (AchE) technique.

RESULTS

Approximately 44 thick nerve bundles were found to enter the human cornea in a relatively equal distribution round the limbus and move randomly towards the central cornea. At the mid-peripheral zone, anterior stromal nerves showed a characteristic budding and branching pattern. After passing through Bowman's zone they were noted to terminate into bulb-like thickenings from which multiple sub-basal nerves arose. The perforation sites were predominantly located in the mid-peripheral cornea. The orientation of sub-basal nerves was mainly vertical at their origin from the perforation sites. Nerves from all directions converged towards the infero-central cornea to form a characteristic clockwise whorl pattern.

CONCLUSIONS

This study provides a comprehensive account of the architecture and distribution of nerves in the human cornea. It reconciles some of the existing information obtained from other modalities of investigation and identifies some novel features that provide a more complete picture of corneal innervation.

Epidemiological pathology of dementia: attributable-risks at death in the Medical Research Council Cognitive Function and Ageing Study

BACKGROUND

Dementia drug development aims to modulate pathological processes that cause clinical syndromes. Population data (epidemiological neuropathology) will help to model and predict the potential impact of such therapies on dementia burden in older people. Presently this can only be explored through post mortem findings. We report the attributable risks (ARs) for dementia at death for common age-related degenerative and vascular pathologies, and other factors, in the MRC Cognitive Function and Ageing Study (MRC CFAS).

METHODS AND FINDINGS

A multicentre, prospective, longitudinal study of older people in the UK was linked to a brain donation programme. Neuropathology of 456 consecutive brain donations assessed degenerative and vascular pathologies. Logistic regression modelling, with bootstrapping and sensitivity analyses, was used to estimate AR at death for dementia for specific pathologies and other factors. The main contributors to AR at death for dementia in MRC CFAS were age (18%), small brain (12%), neocortical neuritic plaques (8%) and neurofibrillary tangles (11%), small vessel disease (12%), multiple vascular pathologies (9%), and hippocampal atrophy (10%). Other significant factors include cerebral amyloid angiopathy (7%) and Lewy bodies (3%).

CONCLUSIONS

Such AR estimates cannot be derived from the living population; rather they estimate the relative contribution of specific pathologies to dementia at death. We found that multiple pathologies determine the overall burden of dementia. The impact of therapy targeted to a specific pathology may be profound when the dementia is relatively "pure," but may be less impressive for the majority with mixed disease, and in terms of the population. These data justify a range of strategies, and combination therapies, to combat the degenerative and vascular determinants of cognitive decline and dementia. Please see later in the article for the Editors' Summary.

Greater loss of axons in primary progressive multiple sclerosis plaques compared to secondary progressive disease

The pathological substrate of progressive disability in multiple sclerosis is hypothesized to be axonal loss. Differences in the demographic, pathological and radiological features of patients with primary progressive compared with secondary progressive multiple sclerosis raise the question as to whether they actually represent separate clinical entities. So far, large pathological studies comparing axonal damage between primary progressive and secondary progressive multiple sclerosis have not been reported. In this clinico-pathological study we examined the cervical spinal cord in patients with primary and secondary progressive multiple sclerosis. Human cervical spinal cord was derived at autopsy from 54 patients (17 primary progressive, 30 secondary progressive and 7 controls). Tissue was stained immunohistochemically and examined to determine: (i) the number of surviving corticospinal tract axons; (ii) the extent of grey and white matter demyelination; (iii) the degree of inflammation inside and outside of lesions; and (iv) the relationship between demyelination and axonal loss. Associated clinical data was used to calculate expanded disability status scale for each patient preceding death. Motor disability in the primary progressive and secondary progressive groups was similar preceding death. Secondary progressive multiple sclerosis patients showed considerably more extensive demyelination of both the white and grey matter of the cervical spinal cord. The total number of corticospinal axons was equally low in primary progressive and secondary progressive multiple sclerosis groups versus controls. The reduction of axonal density in demyelinated regions compared to normal appearing white matter was significantly more extensive in primary progressive versus secondary progressive patients (33% reduction versus 16% reduction, P < 0.001). These findings suggest axonal loss is the pathological substrate of progressive disability in both primary progressive and secondary progressive multiple sclerosis with a common plaque-centred mechanism. More extensive axonal loss within areas of demyelination in primary progressive multiple sclerosis could explain high levels of axonal loss observed in these patients despite low levels of demyelination.

Pediatric ependymoma: biological perspectives

Pediatric ependymomas are enigmatic tumors that continue to present a clinical management challenge despite advances in neurosurgery, neuroimaging techniques, and radiation therapy. Difficulty in predicting tumor behavior from clinical and histological factors has shifted the focus to the molecular and cellular biology of ependymoma in order to identify new correlates of disease outcome and novel therapeutic targets. This article reviews our current understanding of pediatric ependymoma biology and includes a meta-analysis of all comparative genomic hybridization (CGH) studies done on primary ependymomas to date, examining more than 300 tumors. From this meta-analysis and a review of the literature, we show that ependymomas in children exhibit a different genomic profile to those in adults and reinforce the evidence that ependymomas from different locations within the central nervous system (CNS) are distinguishable at a genomic level. Potential biological markers of prognosis in pediatric ependymoma are assessed and the ependymoma cancer stem cell hypothesis is highlighted with respect to tumor resistance and recurrence. We also discuss the shifting paradigm for treatment modalities in ependymoma that target molecular alterations in tumor-initiating cell populations.

An investigation of WNT pathway activation and association with survival in central nervous system primitive neuroectodermal tumours (CNS PNET)

Central nervous system primitive neuroectodermal tumours (CNS PNET) are high-grade, predominantly paediatric, brain tumours. Previously they have been grouped with medulloblastomas owing to their histological similarities. The WNT/β-catenin pathway has been implicated in many tumour types, including medulloblastoma. On pathway activation β-catenin (CTNNB1) translocates to the nucleus, where it induces transcription of target genes. It is commonly upregulated in tumours by mutations in the key pathway components APC and CTNNB1. WNT/β-catenin pathway status was investigated by immunohistochemical analysis of CTNNB1 and the pathway target cyclin D1 (CCND1) in 49 CNS PNETs and 46 medulloblastomas. The mutational status of APC and CTNNB1 (β-catenin) was investigated in 33 CNS PNETs and 22 medulloblastomas. CTNNB1 nuclear localisation was seen in 36% of CNS PNETs and 27% of medulloblastomas. A significant correlation was found between CTNNB1 nuclear localisation and CCND1 levels. Mutations in CTNNB1 were identified in 4% of CNS PNETs and 20% of medulloblastomas. No mutations were identified in APC. A potential link between the level of nuclear staining and a better prognosis was identified in the CNS PNETs, suggesting that the extent of pathway activation is linked to outcome. The results suggest that the WNT/β-catenin pathway plays an important role in the pathogenesis of CNS PNETs. However, activation is not caused by mutations in CTNNB1 or APC in the majority of CNS PNET cases.

Regional variations in the extent and pattern of grey matter demyelination in multiple sclerosis: a comparison between the cerebral cortex, cerebellar cortex, deep grey matter nuclei and the spinal cord

BACKGROUND

Substantial grey matter (GM) demyelination occurs in both the cerebral cortex and spinal cord in multiple sclerosis (MS). GM demyelination also occurs in the cerebellar cortex and the deep GM nuclei of the brain. However, no study has made a direct "within subject" comparison of the extent of GM pathology between these regions.

AIM

To examine the extent and pattern of GM demyelination in the motor cortex, cingulate gyrus, cerebellum, thalamus and spinal cord in MS.

METHODS

Postmortem study using material from 14 MS cases and three controls. Sections were taken from the five predetermined areas and stained for proteolipid protein. The extent of GM and white matter (WM) demyelination was assessed in each region.

RESULTS AND CONCLUSION

Overall, 28.8% of the GM was demyelinated compared with 15.6% of the WM (p<0.001), with demyelination being greater in the GM than in the WM at each of the anatomical sites. There was substantial variation in the extent of demyelination between the different CNS regions. GM demyelination was most extensive in the spinal cord and cerebellum while WM demyelination was most prominent in the spinal cord.

Rheumatoid arthritis: a novel radiographic projection for hand assessment

Rheumatoid arthritis (RA) is the most common form of inflammatory disease, affecting 1-2% of the population. Posteroanterior (PA) and Brewerton projections are well established in radiographic practice for scoring and monitoring RA, but there is little evidence to demonstrate the diagnostic efficacy of these techniques. This work, by varying the positioning of a cadaveric hand, investigates whether an alternative radiographic projection could yield greater diagnostic information than the traditional techniques. Phase I of the study evaluated moving the hand 15 degrees from the anteroposterior position and then in 5 degrees increments in four directions: medial rotation, lateral rotation, flexion of the wrist and extension of the wrist. Phase II of the study took the optimum projections from Phase I and further manipulated these positions in a direction at right angles to the original position. Images were scored based on joint space visualisation in 29 joints. Results demonstrated that significantly higher diagnostic efficacy was evident with 15 degrees lateral rotation of the hand or 15 degrees flexion at the wrist compared to the Brewerton projection. Either projection is recommended, but on the basis of patient comfort, the latter of these novel positions, now known as the UCD projection, was chosen as the optimum procedure to replace the Brewerton projection. The value of using cadavers for the establishment of optimum radiographic procedures is highlighted.

Spinal cord neuronal pathology in multiple sclerosis

The objective of this study was to assess neuronal pathology in the spinal cord in multiple sclerosis (MS), both within myelinated and demyelinated tissue. Autopsy material was obtained from 38 MS cases and 21 controls. Transverse sections were taken from three spinal cord levels and stained using Luxol Fast Blue/Cresyl Violet and myelin protein immunohistochemistry. Measurements of neuronal number and size were made for all neurons within the anterior horns of the gray matter. Neurons were classified as motoneurons or interneurons according to size criteria. In comparison with controls, both motoneuron and interneuron number were reduced in MS cases at the upper cervical (interneuron P = 0.0549; motoneuron P = 0.0073) and upper thoracic (interneuron P = 0.0507; motoneuron P = 0.0144), but not the lumbar level. Interneuron cross-sectional area was reduced in MS cases at all levels (upper cervical, P = 0.0000; upper thoracic, P = 0.0002; lumbar, P = 0.0337). Neuronal loss appears to be predominantly related to local gray matter plaques, whereas interneuron atrophy occurs in both myelinated and demyelinated areas.

Expression of Sox1, Sox2 and Sox9 is maintained in adult human cerebellar cortex

Neural stem cells (NSCs) have been found to reside in defined areas of the vertebrate brain, where they can be identified by the expression of specific markers such as Sox1, Sox2 and Sox9. In the mouse, expression of Sox1, Sox2 and Sox9 genes has recently been reported outside of these recognised NSC niches, in the Purkinje cell layer of the adult cerebellum. The present study establishes that expression of these marker genes is also found in the human cerebellum beyond the maturation phase. Expression of Sox1, Sox2 and Sox9 was detected at the mRNA level in both foetal and adult cerebellum samples, suggesting that the maintenance of these markers in adult tissue is also observed in the human cerebellum. Expression of these markers was further confirmed at the protein level on human tissue sections, as Sox1, Sox2 and Sox9 expression was detected in the Purkinje cell layer of the adult cerebellum. The present study demonstrates that Sox1 and Sox2 are expressed in the human adult cerebellum, outside of the characterised NSC niches.

Multifactorial analysis of predictors of outcome in pediatric intracranial ependymoma

Pediatric ependymomas are enigmatic tumors, and their clinical management remains one of the more difficult in pediatric oncology. The identification of biological correlates of outcome and therapeutic targets remains a significant challenge in this disease. We therefore analyzed a panel of potential biological markers to determine optimal prognostic markers. We constructed a tissue microarray from 97 intracranial tumors from 74 patients (WHO grade II-III) and analyzed the candidate markers nucleolin, telomerase catalytic subunit (hTERT; antibody clone 44F12), survivin, Ki-67, and members of the receptor tyrosine kinase I (RTK-I) family by immunohistochemistry. Telomerase activity was determined using the in vitro-based telomere repeat amplification protocol assay, and telomere length was measured using the telomere restriction fragment assay. Primary tumors with low versus high nucleolin protein expression had a 5-year event-free survival of 74%+/-13% and 31%+/-7%, respectively. Multivariate analysis identified low nucleolin expression to be independently associated with a more favorable prognosis (hazard ratio=6.25; 95% confidence interval, 1.6-24.2; p=0.008). Ki-67 and survivin correlated with histological grade but not with outcome. Immunohistochemical detection of the RTK-I family did not correlate with grade or outcome. Telomerase activity was evident in 19 of 22 primary tumors, with telomere lengthening and/or maintenance occurring in five of seven recurrent cases. Low nucleolin expression was the single most important biological predictor of outcome in pediatric intracranial ependymoma. Furthermore, telomerase reactivation and maintenance of telomeric repeats appear necessary for childhood ependymoma progression. These findings require corroboration in a clinical trial setting.

Flexible eating and flexible insulin dosing in patients with diabetes: Results of an intensive self-management course

AIMS

To evaluate the outcomes of an established programme to teach patients to match their insulin dose to their carbohydrate intake.

RESEARCH DESIGN AND METHODS

A prospective observational study in Australia (Newcastle, NSW) of 137 consecutive patients with type 1 (n=82) or type 2 diabetes (n=55) over two successive years. Four educational principles were used to teach intensive insulin management and diabetes self-care skills including: carbohydrate counting and insulin dose adjustment, exercise, appropriate treatment of hypoglycaemia and hyperglycaemia, managing sickness, problem solving, communication with health professionals, goal setting, and the importance of support. Outcomes included changes at 4 and 12 months in HbA1c, self-efficacy measured by a diabetes empowerment scale (DES), diabetes specific quality of life (ADDQoL), and problem solving. Both intention to treat and efficacy analyses were performed.

RESULTS

Diabetes-related quality of life and diabetes problem solving skills improved significantly. Excluding 16 people who failed to adopt intensive insulin management and 24 who started with an HbA1c less than 7%, intention to treat analysis showed the average HbA1c fell from 8.7% initially to 8.1% at 12 months and the number of people with an HbA1c of less than 8% rose from 67 (48.9%) before the program to 86 (62.8%) afterwards.

CONCLUSIONS

An intensive diabetes self-management program led to improvements in HbA1c, empowerment, and quality of life that were largely sustained at 1 year. This is all the more remarkable given that the intervention was once only, entailed no long-term follow-up, and took place in normal clinical operations.

Enterobacter sakazakii invades brain capillary endothelial cells, persists in human macrophages influencing cytokine secretion and induces severe brain pathology in the neonatal rat

Enterobacter sakazakii is an opportunistic pathogen associated with contaminated powdered infant formula and a rare cause of Gram-negative sepsis that can develop into meningitis and brain abscess formation in neonates. Bacterial pathogenesis remains to be fully elucidated. In this study, the host inflammatory response was evaluated following intracranial inoculation of Ent. sakazakii into infant rats. Infiltrating macrophages and neutrophils composed multiple inflammatory foci and contained phagocytosed bacteria. Several genotypically distinct Ent. sakazakii strains (16S cluster groups 1-4) were shown to invade rat capillary endothelial brain cells (rBCEC4) in vitro. Further, the persistence of Ent. sakazakii in macrophages varied between strains. The presence of putative sod genes and SOD activity may influence the survival of acidic conditions and macrophage oxidase and contribute to Ent. sakazakii intracellular persistence. The influence of macrophage uptake of Ent. sakazakii on immunoregulatory cytokine expression was assessed by ELISA. This demonstrated that the IL-10/IL-12 ratio is high after 24 h. This is suggestive of a type 2 immune response which is inefficient in fighting intracellular infections. These findings may help explain how the diversity in virulence traits among Ent. sakazakii isolates and an unsuccessful immune response contribute to the opportunistic nature of this infection.

Repeated novel cage exposure-induced improvement of early Alzheimer's-like cognitive and amyloid changes in TASTPM mice is unrelated to changes in brain endocannabinoids levels

Environmental factors (e.g. stress, exercise, enrichment) are thought to play a role in the development of Alzheimer's disease later in life. We investigated the influence of repeated novel cage exposure on the development of early Alzheimer's-like pathology in adult (4 months old) double transgenic mice over-expressing the amyloid precursor protein and presenilin-1 genes (TASTPM mouse line). The procedure involves the repeated placement of the animal into a novel clean cage, a manipulation which induces a stress response and exploratory activity and, as such, can also be seen as a mild form of enrichment. Before and after exposure to the novel cage procedure, separate groups of mice were evaluated for locomotor performance and short-term contextual memory in the fear-conditioning test. Repeated novel cage exposure prevented the onset of a short-term memory deficit that was apparent in 5.5- but not 4-month-old TASTPM mice, without reversing the deficit in extinction already evident at 4 months of age. Brain regional levels of soluble and insoluble amyloid and of endocannabinoids were quantified. Novel cage exposure attenuated soluble and insoluble amyloid accumulation in the hippocampus and frontal cortex, without affecting the age-related increases in regional brain endocannabinoids levels. These beneficial effects are likely to be the consequence of the increase in physical and exploratory activity induced by novel cage exposure and suggest that the impact of environmental factors on Alzheimer's-like changes may be dependent on the degree of activation of stress pathways.

The Met Office Hadley Centre climate modelling capability: the competing requirements for improved resolution, complexity and dealing with uncertainty

Predictions of future climate change require complex computer models of the climate system to represent the full range of processes and interactions that influence climate. The Met Office Hadley Centre uses 'families' of models as part of the Met Office Unified Model Framework to address different classes of problems. The HadGEM family is a suite of state-of-the-art global environment models that are used to reduce uncertainty and represent and predict complex feedbacks. The HadCM3 family is a suite of well established but cheaper models that are used for multiple simulations, for example, to quantify uncertainty or to test the impact of multiple emissions scenarios.

Evaluation of the topical hemostatic efficacy and safety of TISSEEL VH S/D fibrin sealant compared with currently licensed TISSEEL VH in patients undergoing cardiac surgery: a phase 3, randomized, double-blind clinical study

AIM

TISSEEL VH is the only commercially available fibrin sealant indicated as an adjunct to conventional methods of hemostasis during cardiac surgery. A next generation fibrin sealant (TISSEEL VH S/D) has been developed in frozen, ready-to-use form with an added virus inactivation step (solvent/detergent [S/D] treatment) to provide added safety and convenience to the currently licensed product. This study was performed to compare efficacy and safety of the two products.

METHODS

Phase 3, prospective, randomized, double-blind, multicenter study to compare TISSEEL VH S/D to TISSEEL VH during cardiac surgery. The primary efficacy endpoint was the proportion of patients who achieved hemostasis at the primary treatment site within 5 min, and maintained hemostasis until surgical closure.

RESULTS

The proportion of patients who achieved hemostasis at the primary treatment site within 5 min, and maintained hemostasis until surgical closure was 88.2% for TISSEEL VH S/D and 89.6% for TISSEEL VH in the intent-to-treat population. The difference in proportions, TISSEEL VH S/D minus TISSEEL VH, was 1.4% with a standard error of 3.70%. The lower 97.5% confidence bound of this difference was 8.6%, which is above the predefined noninferiority margin of 15%. Therefore, TISSEEL VH S/D is at least as efficacious as TISSEEL VH. The safety profile of TISSEEL VH S/D was very similar to that of currently licensed TISSEEL VH as assessed by the safety endpoints.

CONCLUSION

TISSEEL VH S/D is safe and effective for use as an adjunct to hemostasis in patients undergoing cardiac surgery.

The absence of endogenous beta-endorphin selectively blocks phosphorylation and desensitization of mu opioid receptors following partial sciatic nerve ligation

Phosphorylation of specific sites in the second intracellular loop and in the C-terminal domain have previously been suggested to cause desensitization and internalization of the mu-opioid receptor (MOP-R). To assess sites of MOP-R phosphorylation in vivo, affinity-purified, phosphoselective antibodies were raised against either phosphothreonine-180 in the second intracellular loop (MOR-P1) or the C-terminal domain of MOP-R containing phosphothreonine-370 and phosphoserine-375 (MOR-P2). We found that MOR-P2-immunoreactivity (IR) was significantly increased within the striatum of wild-type C57BL/6 mice after injection of the agonist fentanyl. Pretreatment with the antagonist naloxone blocked the fentanyl-induced increase. Furthermore, mutant mice lacking MOP-R showed only non-specific nuclear MOR-P2-IR before or after fentanyl treatment, confirming the specificity of the MOR-P2 antibodies. To assess whether MOP-R phosphorylation occurs following endogenous opioid release, we induced chronic neuropathic pain by partial sciatic nerve ligation (pSNL), which caused a significant increase in MOR-P2-IR in the striatum. pSNL also induced signs of mu opioid receptor tolerance demonstrated by a rightward shift in the morphine dose response in the tail withdrawal assay and by a reduction in morphine conditioned place preference (CPP). Mutant mice selectively lacking all forms of the beta-endorphin peptides derived from the proopiomelanocortin (Pomc) gene did not show increased MOR-P2-IR, decreased morphine antinociception, or reduced morphine CPP following pSNL. In contrast gene deletion of either proenkephalin or prodynorphin opioids did not block the effects of pSNL. These results suggest that neuropathic pain caused by pSNL in wild-type mice activates the release of the endogenous opioid beta-endorphin, which subsequently induces MOP-R phosphorylation and opiate tolerance.

A novel, non-substrate-based series of glycine type 1 transporter inhibitors derived from high-throughput screening

The synthesis and structure-activity relationships (SAR) of a series of indane and tetralin inhibitors of the type 1 glycine transporter, derived from a high-throughput screening (HTS) hit, are described. Key modifications that reduced the 5HT1B receptor affinity of the HTS hit and the P450 2D6 inhibition of subsequent analogues are delineated. While these modifications led to potent and selective GlyT1 inhibitors, HERG affinity and human microsomal clearance remain an issue for this series of compounds.

Spinal cord gray matter demyelination in multiple sclerosis-a novel pattern of residual plaque morphology

The extent and pattern of gray matter (GM) demyelination in the spinal cord in multiple sclerosis (MS) has not been examined in detail. Human autopsy material was obtained from 36 MS cases and 12 controls. Transverse sections were taken from five levels of the spinal cord (upper cervical, lower cervical, upper thoracic, lower thoracic and lumbar levels) and the extent of GM and white matter (WM) demyelination evaluated using proteolipid protein immunohistochemistry (IHC). The proportion of the GM that was demyelinated (33%) was significantly greater than the proportion of demyelinated WM (20%) (P < 0.0001). Similarly, demyelination was more extensive in the GM than in the WM at each of the five cord levels. The extent of GM demyelination was not significantly different between the five cord levels while WM demyelination was greatest at the upper cervical level. Morphologically, the borders of a proportion of the GM plaques show a strict respect for the GM/WM boundary. We demonstrate that extensive demyelination occurs in the GM of the spinal cord in MS. Myelin protein IHC reveals a novel pattern of residual plaque morphology challenging previous work suggesting that MS plaques display a total disregard for anatomical boundaries.

Morphological characteristics of the limbal epithelial crypt

AIM

In 2005 we reported the discovery of a novel anatomical structure at the limbus, which we termed the limbal epithelial crypt (LEC). The purpose of this study was to further evaluate the distribution, immunophenotypical, and ultra structural characteristics of the LEC as a putative niche of stem cells.

METHODS

Sequential histological sections of human corneo-scleral limbal rims were examined for the presence and distribution of the LEC. Immunophenotypical characterisation of the LEC cells using a panel of antibodies of interest was undertaken. Transmission electron microscopy of the LEC was used to examine the ultra structural and morphometric features of cells within the LEC and adjacent limbus.

RESULTS

A total of 74 LECs were identified in eight corneo-scleral rims. These varied in number, size and distribution within rims. Cells within the crypt demonstrated the following phenotype: CK3-/CK19+/CD 34-/Vimentin+/p63+/Connexin 43+/MIB1 (Ki67)-. Presence of Cx43 was also demonstrated in the rete pegs adjacent to the LEC. Basal cells of the LEC were significantly smaller than basal cells found in adjacent rete pegs and also smaller than suprabasal limbal and central corneal epithelial cells (p<0.05). Morphologically they had a high nuclear:cytoplasmic ratio and were adherent to the underlying basement membrane by means of complex convolutions of cytoplasmic processes.

CONCLUSIONS

LECs are sparse but a consistent finding in the human corneo-scleral limbus. The LEC contains a unique sub-population of cells expressing several characteristics that are consistent with it representing a putative stem cell niche.