Publications by authors named "Peter Dirks"

Glioblastoma is an incurable brain malignancy. By the time of clinical diagnosis, these tumours exhibit a degree of genetic and cellular heterogeneity that provides few clues to the mechanisms that initiate and drive gliomagenesis. Here, to explore the early steps in gliomagenesis, we utilized conditional gene deletion and lineage tracing in tumour mouse models, coupled with serial magnetic resonance imaging, to initiate and then closely track tumour formation.

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Background: Gliomas are a major cause of cancer-related death among children, adolescents, and young adults (age 0-40 years). Primary mismatch repair deficiency (MMRD) is a pan-cancer mechanism with unique biology and therapeutic opportunities. We aimed to determine the extent and impact of primary MMRD in gliomas among children, adolescents, and young adults.

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  • * This study aimed to assess the detectability of circulating-tumor DNA (ctDNA) in cerebrospinal fluid (CSF) as a biomarker for monitoring CNS-GCT patients.
  • * Results showed that ctDNA could be detected in 89% of diagnostic samples, indicating its potential for non-invasive diagnosis and treatment response monitoring in future CNS-GCT research.
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  • * A study at Toronto's Hospital for Sick Children assessed 17 children with a history of childhood ICH, discovering that their average Full Scale IQ (FSIQ) is in the clinically average range but tends to be lower overall.
  • * About 50-60% of participants showed deficits in areas like verbal learning, verbal memory, and processing speed, indicating a need for thorough clinical evaluations of neuropsychological abilities in these youth.
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Adolescents and young adults (AYAs; ages 15-39 years) are a vulnerable population facing challenges in oncological care, including access to specialized care, transition of care, unique tumor biology, and poor representation in clinical trials. Brain tumors are the second most common tumor type in AYA, with malignant brain tumors being the most common cause of cancer-related death. The 2021 WHO Classification for central nervous system (CNS) Tumors highlights the importance of integrated molecular characterization with histologic diagnosis in several tumors relevant to the AYA population.

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Glioblastoma (GBM) is the most common and lethal primary brain tumor in adults and is driven by self-renewing glioblastoma stem cells (GSC) that persist after therapy and seed treatment-refractory recurrent tumors. GBM tumors display a high degree of intra- and intertumoral heterogeneity that is a prominent barrier to targeted treatment strategies. This heterogeneity extends to GSCs that exist on a gradient between two transcriptional states or subtypes termed developmental and injury response.

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Cancer stem cells (CSCs) established from surgical biopsies closely mimic the human context and can be used to investigate disease mechanisms, genetic fitness, and therapeutic evaluation. Here, we present a protocol for the derivation of primary patient-derived CSC lines from ependymal tumors. We describe the necessary steps, from surgical intervention and biopsy to the dissociation of ependymomas to derive cultures.

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Background: The gold standard for evaluation of the severity of moyamoya vasculopathy is the Suzuki grade determined with cerebral catheter angiography (CA). With greater use of magnetic resonance angiography (MRA) it is important to understand if MRA is truly comparable to CA.

Methods: Children with moyamoya were evaluated using the Suzuki score for CA and the modified MRA six-stage Suzuki score to describe the angiographic findings in moyamoya from initial narrowing of the distal internal carotid artery to the "puff of smoke" appearance of the lenticulostriate collaterals and finally to the disappearance of this network of collaterals.

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A broad range of brain pathologies critically relies on the vasculature, and cerebrovascular disease is a leading cause of death worldwide. However, the cellular and molecular architecture of the human brain vasculature remains incompletely understood. Here we performed single-cell RNA sequencing analysis of 606,380 freshly isolated endothelial cells, perivascular cells and other tissue-derived cells from 117 samples, from 68 human fetuses and adult patients to construct a molecular atlas of the developing fetal, adult control and diseased human brain vasculature.

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We identify a population of Protogenin-positive (PRTG) MYC NESTIN stem cells in the four-week-old human embryonic hindbrain that subsequently localizes to the ventricular zone of the rhombic lip (RL). Oncogenic transformation of early Prtg rhombic lip stem cells initiates group 3 medulloblastoma (Gr3-MB)-like tumors. PRTG stem cells grow adjacent to a human-specific interposed vascular plexus in the RL, a phenotype that is recapitulated in Gr3-MB but not in other types of medulloblastoma.

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Background: Moyamoya is a progressive, non-atherosclerotic cerebral arteriopathy that may present in childhood and currently has no cure. Early diagnosis is critical to prevent a lifelong risk of neurological morbidity. Blood-oxygen-level-dependent (BOLD) MRI cerebrovascular reactivity (CVR) imaging provides a non-invasive, in vivo measure of autoregulatory capacity and cerebrovascular reserve.

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Published in 2021, the fifth edition of the World Health Organization (WHO) classification of tumors of the central nervous system (CNS) introduced new molecular criteria for tumor types that commonly occur in either pediatric or adult age groups. Adolescents and young adults (AYAs) are at the intersection of adult and pediatric care, and both pediatric-type and adult-type CNS tumors occur at that age. Mortality rates for AYAs with CNS tumors have increased by 0.

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Objective: Extent of resection (EOR) is the most important modifiable prognostic variable for pediatric patients with posterior fossa ependymoma. An understanding of primary and recurrent ependymoma complications is essential to inform clinical decision-making for providers, patients, and families. In this study, the authors characterize postsurgical complications following resection of primary and recurrent pediatric posterior fossa ependymoma in a molecularly defined cohort.

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  • Ion channels and transporters, part of the "ion permeome," are frequently targeted in drug research, but their specific roles in cancer have been underexplored.
  • A study using pan-cancer transcriptome analysis found that ion permeome genes are often highly expressed in certain cancer types, leading to the identification of 410 survival-associated ion permeome genes across 33 cancers.
  • The genes GJB2 and SCN9A are particularly noteworthy for their high expression in glioblastoma, influencing tumor behavior and patient survival, suggesting these genes could be leveraged for new cancer therapies.
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Glioblastoma stem cells (GSCs) play an important role in the invasive nature of glioblastoma (GBM); yet, the mechanisms driving this behavior are poorly understood. To recapitulate tumor invasion in vitro, we developed a GBM tumor-mimetic hydrogel using extracellular matrix components upregulated in patients. We show that our hydrogel facilitates the infiltration of a subset of patient-derived GSCs, differentiating samples based on phenotypic invasion.

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Background: Cerebellar mutism syndrome (CMS) is a common and debilitating complication of posterior fossa tumor surgery in children. Affected children exhibit communication and social impairments that overlap phenomenologically with subsets of deficits exhibited by children with Autism spectrum disorder (ASD). Although both CMS and ASD are thought to involve disrupted cerebro-cerebellar circuitry, they are considered independent conditions due to an incomplete understanding of their shared neural substrates.

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  • Intracranial pyogenic complications from sinusitis in children can lead to serious health issues, as revealed by a 20-year study examining clinical and microbiologic data from 104 cases.
  • The majority of affected children were male, with common complications including epidural and subdural empyema, and a significant portion required neurosurgery or otolaryngologic intervention.
  • The findings highlight the prevalence of Streptococcus anginosus and polymicrobial infections, indicating the necessity for broad-spectrum antibiotics and the importance of timely diagnosis to reduce the likelihood of lasting neurologic effects.
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Unlabelled: Immune checkpoint inhibition (ICI) is effective for replication-repair-deficient, high-grade gliomas (RRD-HGG). The clinical/biological impact of immune-directed approaches after failing ICI monotherapy is unknown. We performed an international study on 75 patients treated with anti-PD-1; 20 are progression free (median follow-up, 3.

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Glioblastoma (GBM) is an incurable brain cancer that lacks effective therapies. Here we show that EAG2 and Kvβ2, which are predominantly expressed by GBM cells at the tumor-brain interface, physically interact to form a potassium channel complex due to a GBM-enriched Kvβ2 isoform. In GBM cells, EAG2 localizes at neuron-contacting regions in a Kvβ2-dependent manner.

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  • Surgical revascularization can lower long-term stroke risks in children with moyamoya arteriopathy, but increases stroke risk during surgery, highlighting a need for improved perioperative care practices.
  • Experts used a modified Delphi process to gather insights from 30 specialists on effective management strategies for these patients, culminating in 39 consensus statements.
  • Key recommendations include preadmission for high-risk children, mandatory intravenous fluids around surgery, continuous aspirin usage, and rigorous monitoring of vital signs and neurological status post-surgery.
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Cerebellar granule neurons (CGNs) are the most abundant neurons in the human brain. Dysregulation of their development underlies movement disorders and medulloblastomas. It is suspected that these disorders arise in progenitor states of the CGN lineage, for which human models are lacking.

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Self-renewal is a crucial property of glioblastoma cells that is enabled by the choreographed functions of chromatin regulators and transcription factors. Identifying targetable epigenetic mechanisms of self-renewal could therefore represent an important step toward developing effective treatments for this universally lethal cancer. Here we uncover an epigenetic axis of self-renewal mediated by the histone variant macroH2A2.

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  • This study analyzed how various factors like age at stroke, lesion size, and socioeconomic status affect neurocognitive functioning in young people who experienced pediatric strokes.
  • Results showed that larger lesion sizes and lower socioeconomic status were linked to poorer outcomes, particularly in areas like attention and executive functioning.
  • Overall, the findings emphasize the importance of understanding these predictors to help clinicians assess and develop better treatment plans for youth recovering from strokes.
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Background: The Belonidae family of fish has been implicated in various penetrating injuries; to date, however, there have been limited reports of brain injury due to this species.

Observations: The authors present the case of a young patient who suffered an ocular penetrating injury from a needlefish with a resultant cavernous sinus thrombosis and concomitant carotid-cavernous fistula. This case highlights the interdisciplinary management of this rare condition through a strategy of anticoagulation titration to the endpoint of fistula closure.

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