Christian Hartmann

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A recent study reported on mutations in the active site of the isocitrate dehydrogenase (IDH1) gene in 12% of glioblastomas. All mutations detected resulted in an amino acid exchange in position 132. We analyzed the genomic region spanning wild type R132 of IDH1 by direct sequencing in 685 brain tumors including 41 pilocytic astrocytomas, 12 subependymal(More)
This paper investigates the connectivity of wireless multihop networks in a log--normal shadow fading environment. Assuming a spatial Poisson distribution of the network nodes, we derive (a) a closed--form expression for the probability that a node is isolated and (b) a tight bound for the minimum node density that is needed to obtain an almost surely(More)
In modern clinical neuro-oncology, histopathological diagnosis affects therapeutic decisions and prognostic estimation more than any other variable. Among high-grade gliomas, histologically classic glioblastomas and anaplastic oligodendrogliomas follow markedly different clinical courses. Unfortunately, many malignant gliomas are diagnostically challenging;(More)
Glioblastoma (GBM) is a brain tumor that carries a dismal prognosis and displays considerable heterogeneity. We have recently identified recurrent H3F3A mutations affecting two critical amino acids (K27 and G34) of histone H3.3 in one-third of pediatric GBM. Here, we show that each H3F3A mutation defines an epigenetic subgroup of GBM with a distinct global(More)
PURPOSE The standard of care for anaplastic gliomas is surgery followed by radiotherapy. The NOA-04 phase III trial compared efficacy and safety of radiotherapy followed by chemotherapy at progression with the reverse sequence in patients with newly diagnosed anaplastic gliomas. PATIENTS AND METHODS Patients (N = 318) were randomly assigned 2:1:1(More)
Somatic mutations in the IDH1 gene encoding cytosolic NADP+-dependent isocitrate dehydrogenase have been shown in the majority of astrocytomas, oligodendrogliomas and oligoastrocytomas of WHO grades II and III. IDH2 encoding mitochondrial NADP+-dependent isocitrate dehydrogenase is also mutated in these tumors, albeit at much lower frequencies. Preliminary(More)
Missense mutations of the V600E type constitute the vast majority of tumor-associated somatic alterations in the v-RAF murine sarcoma viral oncogene homolog B1 (BRAF) gene. Initially described in melanoma, colon and papillary thyroid carcinoma, these alterations have also been observed in primary nervous system tumors albeit at a low frequency. We analyzed(More)
PURPOSE The prognostic value of genetic alterations characteristic of glioblastoma in patients treated according to present standards of care is unclear. PATIENTS AND METHODS Three hundred one patients with glioblastoma were prospectively recruited between October 2004 and December 2006 at the clinical centers of the German Glioma Network. Two hundred(More)
This paper analyzes the impact of beamforming antennas on the topological connectivity of multihop wireless networks. As a metric for the connectivity of the network, we use the percentage P (path) of nodes that are connected via a multihop path. We show that simple randomized beamforming — i.e., each node adjusts its main beam into a randomly chosen(More)
WHO grading of human brain tumors extends beyond a strictly histological grading system by providing a basis predictive for the clinical behavior of the respective neoplasm. For example, patients with glioblastoma WHO grade IV usually show a less favorable clinical course and receive more aggressive first-line treatment than patients with anaplastic(More)