C-MYC expression in medulloblastoma and its prognostic value.

To identify prognostic factors in medulloblastoma, a common malignant brain tumor of childhood, expression of the oncogene c-myc was examined at the mRNA level by in situ hybridization. c-myc mRNA expression was observed in 30 of 72 tumors (42%). The c-myc gene copy number was determined by quantitative PCR from genomic DNA of paraffin-embedded tumors. c-myc gene amplification was present in 5 of 62 cases (8.3%). Therefore, c-myc amplification was obviously not the cause of c-myc mRNA expression in most samples. Kaplan-Meier estimation revealed a significant correlation between c-myc mRNA expression and survival (total mean follow-up 4.6 +/- 3.6 years, log-rank p = 0.02). Multivariate logistic regression analysis including sex, age, histological type, degree of surgical resection and expression of synaptophysin, GFAP and c-myc, was carried out on 54 patients who received both radiotherapy and chemotherapy. The analysis identified expression of c-myc as an independent predictive factor of death from disease.

Neural expression profile of Elav-like genes in human brain.

BACKGROUND: Hel-N1 and HuD belong to the elav gene family and have a considerable role in neuronal development. However, there is only limited information available on the expression profile in human brain and neural tumor cell lines. METHOD: Therefore, RT-PCR analysis has been performed on human fetal, normal adult, and psychiatric brains (from patients with schizophrenia, Alzheimer's disease, and alcoholism) as well as 20 glioblastoma and 9 medulloblastoma cell lines. RESULTS: Both, Hel-N1 and HuD were abundantly expressed in all brain samples with no obvious difference. However, the neural tumor cell lines showed a differential expression pattern. The medulloblastoma cell lines expressed at least one of the genes in a frequency of 67% for HuD and 78% for Hel-N1 transcripts, respectively. In contrast to the glioblastoma cell lines, which revealed no evidence for HuD RT-PCR products. Surprisingly, 55% of the glioblastoma cell lines showed Hel-N1 expression. CONCLUSION: These observations indicate that Hel-N1 and HuD participate in molecular processes in human brain, both during development and in the mature adult brain. Hel-N1 and HuD transcriptional activity are stable markers for medulloblastoma cell lines, a tumor, which is thought to be derived from a neuronal precursor cell. The role of Hel-N1 in glioblastomas, the most prominent representative of the glial tumors is presently unclear. This finding is the first indication for a possible involvement of an Elav-like gene product in the glial cell lineage.

The production and utilization of nitric oxide by a new, denitrifying strain of Pseudomonas aeruginosa.

When a new strain of Pseudomonas aeruginosa was grown aerobically and then transferred to anaerobic conditions, cells reduced NO3- quantitatively to NO2- in NO3(-)-respiration. In the absence of nitrate, NO2- was immediately reduced to NO or N2O but not to N2 indicating that NO2(-)-reductase but not N2O-reductase was active. The formation of the products NO or N2O depended on the pH in the medium and the concentration of NO2- present. When P. aeruginosa was grown anaerobically for at least three days N2O-reductase was also active. Such cells reduced NO to N2 via N2O. The new strain generated at H(+)-gradient and grew by reducing N2O to N2 but not by converting NO to N2O. For comparison, Azospirillum brasilense Sp7 showed the same pattern of NO-reduction. In contrast, Paracoccus denitrificans formed 3.5 H+/NO during the reduction of NO to N2O in oxidant pulse experiments but could not grow in the presence of NO. Thus the NO-reduction pattern in P. denitrificans on one side and P. aeruginosa and A. brasilense on the other was very different. The mechanistic implications of such differences are discussed.