Tumors derived from rat C6 cell implants into rat brain exhibit similar morphological characteristics and degree of vascularization to human glioblastomas. To establish a molecular basis for C6 gliosarcoma malignancy, we have constructed a molecular profile of the most abundantly expressed genes, using serial analysis of gene expression (SAGE). Sequence tags (1168) representing 738 individual transcripts were collected and tag-to-gene mapping was carried out using the UniGene data set for rat. Differentially expressed C6 transcripts were identified by comparison of tags collected for C6 cells with a similar number (1002) of tags from a rat primary astrocyte library. Genes found to be expressed at increased levels in C6 cells are associated with cell surface interactions, migration, or metastasis formation and proliferation. These include the receptor for hyaluronan-mediated motility (RHAMM), S-100 related protein 42A, galectin I, preproenkephalin, osteopontin, autocrine motility factor, alpha-tubulin, ad1 antigen, and cofilin. In addition, a tag with no database match probably representing a previously uncharacterized transcript was differentially expressed in C6 cells. Transcripts showing reduced expression in C6 cells relative to astrocytes included the extracellular matrix glycoprotein osteonectin/SPARC (secreted protein, acidic, rich in cysteine), actin-binding proteins thymosins beta-4 and beta-10, the cysteine protease inhibitor cystatin C, the actin-gelling protein SM22/transgelin, and ferritin-H. SAGE results were confirmed by Northern blot for all transcripts tested, reaffirming the value of the SAGE technique for expression profiling in cancer biology.
Background Intracranial pressure (ICP) monitoring requires placing a hole in the skull through which an invasive pressure monitor is inserted into the brain. This approach has risks for the patient and is expensive. We have developed a non-invasive brain pulse monitor that uses red light to detect a photoplethysmographic (PPG) signal arising from the blood vessels on the brain’s cortical surface. The brain PPG and the invasive ICP waveform share morphological features which may allow measurement of the intracranial pressure. Methods We enrolled critically ill patients with an acute brain injury with invasive ICP monitoring to assess the new monitor. A total of 24 simultaneous invasive ICP and brain pulse monitor PPG measurements were undertaken in 12 patients over a range of ICP levels. Results The waveform morphologies were similar for the invasive ICP and brain pulse monitor PPG approach. Both methods demonstrated a progressive increase in the amplitude of P2 relative to P1 with increasing ICP levels. An automated algorithm was developed to assess the PPG morphological features in relation to the ICP level. A correlation was demonstrated between the brain pulse waveform morphology and ICP levels, R 2 =0.66, P < 0.001. Conclusion The brain pulse monitor’s PPG waveform demonstrated morphological features were similar to the invasive ICP waveform over a range of ICP levels, these features may provide a method to measure ICP levels. Trial Registration ACTRN12620000828921.
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