Publications by authors named "Iris Heer"

Background: In children, monitoring depth of anesthesia is challenging because of the still developing brain. Electroencephalographic density spectral array monitoring provides age- and anesthetic drug-specific electroencephalographic patterns, making it suitable for use in children. Yet, not much is known about the benefits of using density spectral array on post-operative recovery in children.

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  • Accurate grading of IDH-mutant gliomas is crucial for predicting patient outcomes and selecting treatment strategies, yet histological grading remains difficult, with limited molecular markers available.
  • Researchers performed RNA-sequencing on 138 IDH-mutant astrocytomas from the CATNON trial and analyzed multi-omics data to create a Continuous Grading Coefficient (CGC), which proved to be a better survival predictor than current grading systems.
  • The study identified four distinct transcriptional clusters linked to various gene expression patterns, revealing that higher-grade IDH-mutant astrocytomas exhibit DNA-methylation signatures correlated with increased cell cycling, tumor de-differentiation, and changes in the extracellular matrix.
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Accurate grading of IDH-mutant gliomas defines patient prognosis and guides the treatment path. Histological grading is however difficult and, apart from CDKN2A/B homozygous deletions in IDH-mutant astrocytomas, there are no other objective molecular markers used for grading. Experimental Design: RNA-sequencing was conducted on primary IDH-mutant astrocytomas (n=138) included in the prospective CATNON trial, which was performed to assess the prognostic effect of adjuvant and concurrent temozolomide.

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Introduction: Propofol and sevoflurane have a long history in pediatric anesthesia. Combining both drugs at low dose levels offers new opportunities. However, monitoring the hypnotic effects of this drug combination in children is challenging, because the currently available processed EEG-based systems are insufficiently validated in young children and the co-administration of anesthetics.

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  • The T2-FLAIR mismatch sign on MRI indicates a specific feature of IDH-mutant astrocytomas, showing signal loss that may relate to microcystic changes in the tumor, but not all tumors display this sign.
  • A study of patients with lower-grade IDH-mutant astrocytomas aimed to explore the prognostic significance of this sign after surgical resections and its relationship with tumor characteristics.
  • Results revealed that the presence of the T2-FLAIR mismatch is associated with Grade 2 tumors, a better overall survival rate, and expansive tumor growth, suggesting its potential as a positive prognostic marker for these patients.
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  • Researchers studied glioblastoma, a type of brain cancer, to improve treatments by looking at how these tumors change over time.
  • They used special tests (RNA sequencing) on tumor samples from patients to see how the cells and their environment evolve when the tumors come back after treatment.
  • The study found that instead of changing the main cancer genes, the tumors' surroundings changed a lot, which affected how patients did after their tumors came back.
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Depth of hypnosis monitoring using numerical index based processed electroencephalography is part of the standard anesthesia equipment in many operating rooms. Unfortunately, this method has its limitations, especially in pediatric patients. Therefore, there is an increasing interest in raw electroencephalography parameters.

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  • There's a significant challenge in glioma research due to the absence of in vitro models that mimic the characteristics of glioma cells found in live tissues.
  • Researchers have developed a 3D-engineered scaffold using advanced polymerization techniques to create a more accurate cell culture system with patient-derived glioma cells.
  • This 3D model allows for improved observation of cell behavior and structure compared to traditional 2D cultures, making it a valuable tool for studying brain cancer mechanics and testing potential treatments.
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Purpose: Despite recent advances in the molecular characterization of gliomas, it remains unclear which patients benefit most from which second-line treatments. The TAVAREC trial was a randomized, open-label phase II trial assessing the benefit of the addition of the angiogenesis inhibitor bevacizumab to treatment with temozolomide in patients with a first enhancing recurrence of World Health Organization grade 2 or 3 glioma without 1p/19q codeletion. We evaluated the prognostic significance of genome-wide DNA methylation profiles and copy-number variations on the TAVAREC trial samples.

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Purpose: In a post hoc analysis of the CATNON trial (NCT00626990), we explored whether adding temozolomide to radiotherapy improves outcome in patients with IDH1/2 wildtype (wt) anaplastic astrocytomas with molecular features of glioblastoma [redesignated as glioblastoma, isocitrate dehydrogenase-wildtype (IDH-wt) in the 2021 World Health Organization (WHO) classification of central nervous system tumors].

Patients And Methods: From the randomized phase III CATNON study examining the addition of adjuvant and concurrent temozolomide to radiotherapy in anaplastic astrocytomas, we selected a subgroup of IDH1/2wt and H3F3Awt tumors with presence of TERT promoter mutations and/or EGFR amplifications and/or combined gain of chromosome 7 and loss of chromosome 10. Molecular abnormalities including MGMT promoter methylation status were determined by next-generation sequencing, DNA methylation profiling, and SNaPshot analysis.

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Background: EGFR is among the genes most frequently altered in glioblastoma, with exons 2-7 deletions (EGFRvIII) being among its most common genomic mutations. There are conflicting reports about its prognostic role and it remains unclear whether and how it differs in signaling compared with wildtype EGFR.

Methods: To better understand the oncogenic role of EGFRvIII, we leveraged 4 large datasets into 1 large glioblastoma transcriptome dataset (n = 741) alongside 81 whole-genome samples from 2 datasets.

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The brain is considered as the major target organ of anesthetic agents. Despite that, a reliable means to monitor its function during anesthesia is lacking. Mid latency auditory evoked potentials are known to be sensitive to anesthetic agents and might therefore be a measure of hypnotic state in pediatric patients.

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Background: The CATNON trial investigated the addition of concurrent, adjuvant, and both current and adjuvant temozolomide to radiotherapy in adults with newly diagnosed 1p/19q non-co-deleted anaplastic gliomas. The benefit of concurrent temozolomide chemotherapy and relevance of mutations in the IDH1 and IDH2 genes remain unclear.

Methods: This randomised, open-label, phase 3 study done in 137 institutions across Australia, Europe, and North America included patients aged 18 years or older with newly diagnosed 1p/19q non-co-deleted anaplastic gliomas and a WHO performance status of 0-2.

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Background: Survival in patients with IDH1/2-mutant (mt) anaplastic astrocytomas is highly variable. We have used the prospective phase 3 CATNON trial to identify molecular factors related to outcome in IDH1/2mt anaplastic astrocytoma patients.

Methods: The CATNON trial randomized 751 adult patients with newly diagnosed 1p/19q non-codeleted anaplastic glioma to 59.

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Somatic mutations in the isocitrate dehydrogenase genes IDH1 and IDH2 occur at high frequency in several tumour types. Even though these mutations are confined to distinct hotspots, we show that gliomas are the only tumour type with an exceptionally high percentage of IDH1 mutations. Patients harbouring IDH1 mutated tumours have lower levels of genome-wide DNA-methylation, and an associated increased gene expression, compared to tumours with other IDH1/2 mutations ("non-R132H IDH1/2 mutations").

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Background: In children, the preoperative hydration status is an important part of the overall clinical assessment. The assumed preoperative fluid deficit is often routinely replaced during induction without knowing the child's actual fluid status.

Aim: We investigated the predictive value of the Pleth Variability Index as a measure of fluid responsiveness in spontaneously breathing anesthetized children.

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Background: The randomized phase II INTELLANCE-2/EORTC_1410 trial on EGFR-amplified recurrent glioblastomas showed a trend towards improved overall survival when patients were treated with depatux-m plus temozolomide compared with the control arm of alkylating chemotherapy only. We here performed translational research on material derived from this clinical trial to identify patients that benefit from this treatment.

Methods: Targeted DNA-sequencing and whole transcriptome analysis was performed on clinical trial samples.

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Background: Clinical responses to EGFR tyrosine kinase inhibitors (TKIs) are restricted to tumors harboring specific activating mutations and even then, not all tyrosine kinase inhibitors provide clinical benefit. All TKIs however, effectively inhibit EGFR phosphorylation regardless of the mutation present.

Methods: High-throughput, high-content imaging analysis, western blot, Reversed phase protein arrays, mass spectrometry and RT-qPCR.

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Background: Recently published articles address concerns about the safe use of currently available index-based depth of hypnosis monitors. Electroencephalographic Density Spectral Array monitoring facilitates the interpretation of unprocessed electroencephalogram data, providing the anesthesiologist with real-time drug-specific information on hypnotic depth. The primary aim of this study was to investigate the clinical applicability of Density Spectral Array with a commercially available monitor as the Narcotrend EEG monitor in teenagers under procedural sedation using propofol.

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Background: Precision medicine trials targeting the epidermal growth factor receptor (EGFR) in glioblastoma patients require selection for EGFR-amplified tumors. However, there is currently no gold standard in determining the amplification status of EGFR or variant III (EGFRvIII) expression. Here, we aimed to determine which technique and which cutoffs are suitable to determine EGFR amplification status.

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Objectives: From a pharmaceutical point of view, we see a need to develop stable preclinical test systems to identify and investigate effects of potentized remedies as used in Anthroposophic Medicine and Homeopathy. We evaluated a plant bioassay regarding its capacity to distinguish homeopathic remedies from placebo, applied as sucrose pillules.

Methods: Pea seed (Pisum sativum L) was soaked for 24 hours in water with dissolved homeopathic or placebo pillules, or in water only.

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Background: Bevacizumab is frequently used in the treatment of recurrent WHO grade II and III glioma, but without supporting evidence from randomised trials. Therefore, we assessed the use of bevacizumab in patients with first recurrence of grade II or III glioma who did not have 1p/19q co-deletion.

Methods: The TAVAREC trial was a randomised, open-label phase 2 trial done at 32 centres across Europe in patients with locally diagnosed grade II or III glioma without 1p/19q co-deletion, with a first and contrast-enhancing recurrence after initial radiotherapy or chemotherapy, or both.

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