Distinctive molecular profiles of high-grade and low-grade gliomas based on oligonucleotide microarray analysis

Astrocytomas are heterogeneous intracranial glial neoplasms ranging from the highly aggressive malignant glioblastoma multiforme (GBM) to the indolent, low-grade pilocytic astrocytoma. We have investigated whether DNA microarrays can identify gene expression differences between high-grade and low-grade glial tumors. We compared the transcriptional profile of 45 astrocytic tumors including 21 GBMs and 19 pilocytic astrocytomas using oligonucleotide-based microarrays. Of the approximately 6800 genes that were analyzed, a set of 360 genes provided a molecular signature that distinguished between GBMs and pilocytic astrocytomas. Many transcripts that were increased in GBM were not previously associated with gliomas and were found to encode proteins with properties that suggest their involvement in cell proliferation or cell migration. Microarray-based data for a subset of genes was validated using real-time quantitative reverse transcription-PCR. Immunohistochemical analysis also localized the protein products of specific genes of interest to the neoplastic cells of high-grade astrocytomas. Our study has identified a large number of novel genes with distinct expression patterns in high-grade and low-grade gliomas.

The gene for the axonal cell adhesion molecule TAX-1 is amplified and aberrantly expressed in malignant gliomas

The human TAX-1 gene encodes a Mr 135,000 glycoprotein that is transiently expressed on the surface of a subset of neurons during development and is involved in neurite outgrowth. The TAX-1 gene has been mapped to a region on chromosome 1 that has been implicated in microcephaly and the Van der Woude syndrome. Using restriction landmark genome scanning to search for amplified genes in gliomas, we found TAX-1 to be amplified in 2 high-grade gliomas among a group of 26 gliomas investigated. Real-time reverse transcription-quantitative PCR analysis detected high levels of TAX-1 mRNA in glial tumors, even in the absence of TAX-1 gene amplification. Immunohistochemical analysis revealed abundant levels of TAX-1 in neoplastic glial cells of glioblastoma multiforme tumors. Because glial tumors are highly invasive and in view of the role of TAX-1 in neurite outgrowth, we investigated the potential role of TAX-1 in glioma cell migration. Using an in vitro assay, we found that the migration of glioma tumor cells is profoundly reduced in the presence of either an anti-TAX-1 antibody or a TAX-1 antisense oligonucleotide. Our findings suggest that TAX-1 plays a role in glial tumorigenesis and may provide a potential target for therapeutic intervention.

Whole-genome methylation scan in ICF syndrome: hypomethylation of non-satellite DNA repeats D4Z4 and NBL2

The ICF (immunodeficiency, centromeric instability and facial abnormalities) syndrome is a rare recessive disease characterized by immunodeficiency, extraordinary instability of certain heterochromatin regions and mutations in the gene encoding DNA methyltransferase 3B. In this syndrome, chromosomes 1 and 16 are demethylated in their centromere-adjacent (juxtacentromeric) heterochromatin, the same regions that are highly unstable in mitogen-treated ICF lymphocytes and B cell lines. We investigated the methylation abnormalities in CpG islands of B cell lines from four ICF patients and their unaffected parents. Genomic DNA digested with a CpG methylation-sensitive restriction enzyme was subjected to two-dimensional gel electrophoresis. Most of the restriction fragments were identical in the digests from the patients and controls, indicating that the methylation abnormality in ICF is restricted to a small portion of the genome. However, ICF DNA digests prominently displayed multicopy fragments absent in controls. We cloned and sequenced several of the affected DNA fragments and found that the non-satellite repeats D4Z4 and NBL2 were strongly hypomethylated in all four patients, as compared with their unaffected parents. The high degree of methylation of D4Z4 that we observed in normal cells may be related to the postulated role of this DNA repeat in position effect variegation in facio- scapulohumeral muscular dystrophy and might also pertain to abnormal gene expression in ICF. In addition, our finding of consistent hypomethylation and overexpression of NBL2 repeats in ICF samples suggests derangement of methylation-regulated expression of this sequence in the ICF syndrome.

Use of factor IX complex in warfarin-related intracranial hemorrhage

OBJECTIVE

Anticoagulation-treated patients presenting with intracranial hemorrhage, including subdural hematoma, epidural hematoma, subarachnoid hemorrhage, and intracerebral hemorrhage, require urgent correction of their coagulopathy to prevent worsening hemorrhage and to facilitate surgical intervention when necessary. In this study, we compared the use of fresh frozen plasma (FFP) with that of Factor IX complex concentrate (FIXCC) to achieve rapid correction of warfarin anticoagulation.

METHODS

Patients admitted to a tertiary care center with computed tomography-proven intracranial hemorrhage and a prothrombin time of more than 17 seconds were considered for inclusion in the study protocol. Complete data sets were obtained for eight patients randomized to treatment with FFP and five patients randomized to treatment with FFP supplemented with FIXCC. The prothrombin time and International Normalized Ratio were measured every 2 hours for 14 hours. Correction of anticoagulation was defined as an International Normalized Ratio of < or =1.3.

RESULTS

A difference in repeated International Normalized Ratio measurements during the first 6 hours of correction was observed between the FIXCC and FFP groups (P < 0.03). The rate of correction was greater (P < 0.01) and the time to correction was shorter (P < 0.01) for the FIXCC-treated group. No difference in neurological outcomes was detected between groups, but a higher complication rate was observed for the FFP-treated group.

CONCLUSION

The use of FIXCC accelerated correction of warfarin-related anticoagulation in the presence of intracranial hemorrhage.

Aseptic meningitis caused by Teflon implantation for microvascular decompression. Case report

The authors present the case of a 47-year-old man who, after undergoing microvascular decompression for trigeminal neuralgia, experienced symptomatic pain relief but developed prolonged aseptic meningitis. This case is unusual in that the patient remained dependent on steroid medications for nearly 5 months following the initial surgery and the aseptic meningitis did not resolve until after surgical removal of the Teflon used to pad the trigeminal nerve. The pathophysiological characteristics of the body's reaction to implanted Teflon are discussed along with the rationale for removing this substance in cases of prolonged intractable aseptic meningitis.