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Abstract In this paper, the formation of laser‐induced periodic surface structures (LIPSS) on atomic‐layer deposited MoS2 layers are studied experimentally. The process parameters (laser fluence and the pulse overlap) corresponding to formation of low‐ and high‐spatial frequency LIPSS as well as ablation and modification of the layers are identified for different pulse durations in the range from 0.2 to 10 ps. The role of the temperature accumulation is evaluated by changing the repetition rate from 0.2 to 2 MHz. The negative accumulation effect, i.e., the ablation of the layers becomes more difficult at higher laser pulse overlaps, is also observed. A simple model explaining the transition between different types of the LIPSS and the decrease of the ablation efficiency with the pulse overlap is suggested.

The formation of laser-induced periodic surface structures (LIPSSs) on the atomic layer-deposited (ALD) molybdenum disulfide (MoS2) upon femtosecond laser processing is studied experimentally. Laser-processing parameters such as average laser power and the scan speed at which the formation of the periodic nanostructures takes place are identified. Optical and scanning electron microscopy are applied to identify the parameter regions for the different LIPSS formations and transitions between them. High- and low-spatial frequency LIPSS (HSFL and LSFL) with two distinct periods λLSFL ≈ 1.1 μm and λHSFL ≈ 83 nm can be observed. The HSFL are dominating at higher and the LSFL at lower laser average powers. Formation of LIPSS is found to inhibit laser ablation at lower scan speeds.

Abstract Pediatric high-grade gliomas, specifically diffuse midline gliomas, account for only 20% of clinical cases but are 100% fatal. A majority of the DMG cases are characterized by the signature K27M mutation in histone H3. The H3K27M mutation opposes the function of enhancer of zeste homolog 2 (EZH2), the methyltransferase enzyme of the polycomb repressor complex 2. However, the role of EZH2 in DMG pathogenesis is unclear. In this study, we demonstrate a tumor suppressor function for EZH2 using Ezh2 loss- and gain-of-function studies in H3WT DMG mouse models. Genetic ablation of Ezh2 increased cell proliferation and tumor grade while expression of an Ezh2 gain-of-function mutation significantly reduced tumor incidence and increased tumor latency. Transcriptomic analysis revealed that Ezh2 deletion upregulates an inflammatory response with upregulation of immunoproteasome genes such as Psmb8, Psmb9, and Psmb10. Ezh2 gain-of-function resulted in enrichment of the oxidative phosphorylation/mitochondrial metabolic pathway namely the isocitrate dehydrogenase Idh1/2/3 genes. Pharmacological inhibition of EZH2 augmented neural progenitor cell proliferation, supporting the tumor suppressive role of EZH2. In vivo 7-day treatment of H3K27M DMG tumor bearing mice with an EZH2 inhibitor, Tazemetostat, did not alter proliferation or significantly impact survival. Together our results suggest that EZH2 has a tumor suppressor function in DMG and warrants caution in clinical translation of EZH2 inhibitors to treat patients with DMG.

Diffuse midline gliomas (DMG) are a highly aggressive and universally fatal subgroup of pediatric tumors responsible for the majority of childhood brain tumor deaths. Median overall survival is less than 12 months with a 90% mortality rate at 2 years from diagnosis. Research into the underlying tumor biology and numerous clinical trials have done little to change the invariably poor prognosis. Continued development of novel, efficacious therapeutic options for DMGs remains a critically important area of active investigation. Given that DMGs are not amenable to surgical resection, have only limited response to radiation, and are refractory to traditional chemotherapy, immunotherapy has emerged as a promising alternative treatment modality. This review summarizes the various immunotherapy-based treatments for DMG as well as their specific limitations. We explore the use of cell-based therapies, oncolytic virotherapy or immunovirotherapy, immune checkpoint inhibition, and immunomodulatory vaccination strategies, and highlight the recent clinical success of anti-GD2 CAR-T therapy in diffuse intrinsic pontine glioma (DIPG) patients. Finally, we address the challenges faced in translating preclinical and early phase clinical trial data into effective standardized treatment for DMG patients.

Abstract Background Platelet‐derived growth factor (PDGF) signaling, through the ligand PDGF‐A and its receptor PDGFRA, is important for the growth and maintenance of oligodendrocyte progenitor cells (OPCs) in the central nervous system (CNS). PDGFRA signaling is downregulated prior to OPC differentiation into mature myelinating oligodendrocytes. By contrast, PDGFRA is often genetically amplified or mutated in many types of gliomas, including diffuse midline glioma (DMG) where OPCs are considered the most likely cell‐of‐origin. The cellular and molecular changes that occur in OPCs in response to unregulated PDGFRA expression, however, are not known. Methods Here, we created a conditional knock‐in (KI) mouse that overexpresses wild type (WT) human PDGFRA (hPDGFRA) in prenatal Olig2‐expressing progenitors, and examined in vivo cellular and molecular consequences. Results The KI mice exhibited stunted growth, ataxia, and a severe loss of myelination in the brain and spinal cord. When combined with the loss of p53, a tumor suppressor gene whose activity is decreased in DMG, the KI mice failed to develop tumors but still exhibited hypomyelination. RNA‐sequencing analysis revealed decreased myelination gene signatures, indicating a defect in oligodendroglial development. Mice overexpressing PDGFRA in prenatal GFAP‐expressing progenitors, which give rise to a broader lineage of cells than Olig2‐progenitors, also developed myelination defects. Conclusion Our results suggest that embryonic overexpression of hPDGFRA in Olig2‐ or GFAP‐progenitors is deleterious to OPC development and leads to CNS hypomyelination.

The oncolytic virus Delta-24-RGD is in clinical trial for adult glioma. Here, the authors show that this virus elicits an immune response in mouse models of pediatric high-grade glioma and diffuse pontine intrinsic glioma, resulting in improved survival.

Abstract Pediatric high grade gliomas (pHGG), including diffuse intrinsic pontine gliomas (DIPGs), are aggressive tumors with a dismal outcome. Radiotherapy (RT) is part of the standard of care of these tumors; however, radiotherapy only leads to a transient clinical improvement. Delta-24-RGD is a genetically engineered tumor-selective adenovirus that has shown safety and clinical efficacy in adults with recurrent gliomas. In this work, we evaluated the feasibility, safety and therapeutic efficacy of Delta-24-RGD in combination with radiotherapy in pHGGs and DIPGs models. Our results showed that the combination of Delta-24-RGD with radiotherapy was feasible and resulted in a synergistic anti-glioma effect in vitro and in vivo in pHGG and DIPG models. Interestingly, Delta-24-RGD treatment led to the downregulation of relevant DNA damage repair proteins, further sensitizing tumors cells to the effect of radiotherapy. Additionally, Delta-24-RGD/radiotherapy treatment significantly increased the trafficking of immune cells (CD3, CD4+ and CD8+) to the tumor niche compared with single treatments. In summary, administration of the Delta-24-RGD/radiotherapy combination to pHGG and DIPG models is safe and significantly increases the overall survival of mice bearing these tumors. Our data offer a rationale for the combination Delta-24-RGD/radiotherapy as a therapeutic option for children with these tumors. Significance Delta-24-RGD/radiotherapy administration is safe and significantly increases the survival of treated mice. These positive data underscore the urge to translate this approach to the clinical treatment of children with pHGG and DIPGs.

ACVR1 and H3.1K27M mutations co-occur in diffuse intrinsic pontine glioma. Here, the authors generate a mouse model that recapitulates these genetic lesions and show, using genetic and pharmacological approaches, that the bone morphogenetic protein pathway may be a therapeutic target in these tumours.

Abstract We compared the effect of cholesterol at different concentration on the phase behaviour of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) multilamellar vesicles. We used pressure perturbation differential scanning calorimetry (PPC) that studies a system on the whole by giving access to relevant thermodynamic quantities, and elastic incoherent neutron scattering (EINS) that probes local motions of a system at the atomic level by allowing extraction of dynamical parameters. PPC revealed that the volume expansion coefficient of DMPC and DMPC/Cholesterol samples with 13 and 25 mol% cholesterol is a linear function of the heat capacity measured by differential scanning calorimetry. Neutron backscattering spectroscopy showed that the mean square displacements of H atoms do exhibit an increase with temperature and a decrease under increasing pressure. Cholesterol added at concentrations of 25 and 50 mol% led to suppression of the main phase transition. Taking advantage of these results, the present study aims (i) to show that calorimetry and EINS using the Bicout and Zaccai model equally permit to get access to thermodynamic quantities characterizing pure DMPC and DMPC/cholesterol mixtures, thus directly confirming the theoretical method, and (ii) to validate our approach as function of temperature and of pressure, as both are equally important and complementary thermodynamic variables.

Abstract. Objectives:. To evaluate if a skeletal survey protocol initiated after 48 hours of intubation will decrease time to diagnosis and the treatment of occult fractures in the obtunded polytrauma patient. Design:. Prospective cohort trial with a retrospective cohort comparison arm. Setting:. A single level 1 trauma center. Patients:. Forty-seven patients were identified prospectively for the skeletal survey protocol to screen for occult fractures. The results of the new protocol were compared to a retrospective comparison arm of 46 patients who would have met the same criteria. Intervention:. A skeletal survey protocol using 2-view x-rays of the patients’ extremities to evaluate for any occult injuries after 48 hours of intubation in trauma patients with altered mental status and an unreliable tertiary examination. Main Outcome Measure:. Time to diagnosis of delayed fractures and surgical intervention from date of admission. Results:. The average time to fracture diagnosis and time to surgical intervention in days was not statistically significant between the retrospective and prospective groups [fracture diagnosis: 1.6 ± 5.1 (retrospective) versus 0.5 ± 0.9 (prospective) (P = .159); time to initial surgery: 2.7 ± 5.6 (retrospective) versus 1.1 ± 1.7 (prospective) (P = .064); time to final surgery: 5.3 ± 8.5 (retrospective) versus 2.4 ± 3.0 (prospective) (P = .029)]. In addition, only 24% (4/17) of patients with a delayed fracture diagnosis required surgical intervention making most nonoperative. Conclusions:. Given the inability to have a clinically or statistically significant impact on time to fracture diagnosis or subsequent treatment, we cannot advocate for the routine use of a skeletal survey protocol in obtunded polytrauma patients. Level of Evidence: Level III

Diffuse intrinsic pontine gliomas (DIPGs) are incurable childhood brain tumors, whereby the standard of care is focal radiation, a treatment that provides temporary relief for most patients. Surprisingly, decades of clinical trials have failed to identify additional therapies that can prolong survival in this disease. In this conference manuscript, we discuss how genetic engineered mouse modeling techniques with the use of a retroviral gene delivery system can help dissect the complex pathophysiology of this disease. With this approach, autochthonous murine DIPG models can be readily induced to (1) help interrogate the function of novel genetic alterations in tumorigenesis, (2) identify candidate cells of origin for this disease, (3) address how region-specific differences in the central nervous system influence the process of gliomagenesis, and (4) evaluate novel therapeutics in an immunocompetent model.

Diffuse intrinsic pontine glioma (DIPG) is a rare and incurable brain tumor that arises predominately in children and involves the pons, a structure that along with the midbrain and medulla makes up the brainstem. We have previously developed genetically engineered mouse models of brainstem glioma using the RCAS/Tv-a system by targeting PDGF-B overexpression, p53 loss, and H3.3K27M mutation to Nestin-expressing brainstem progenitor cells of the neonatal mouse. Here we describe a novel mouse model targeting these same genetic alterations to Pax3-expressing cells, which in the neonatal mouse pons consist of a Pax3+/Nestin+/Sox2+ population lining the fourth ventricle and a Pax3+/NeuN+ parenchymal population. Injection of RCAS-PDGF-B into the brainstem of Pax3-Tv-a mice at postnatal day 3 results in 40% of mice developing asymptomatic low-grade glioma. A mixture of low- and high-grade glioma results from injection of Pax3-Tv-a;p53fl/fl mice with RCAS-PDGF-B and RCAS-Cre, with or without RCAS-H3.3K27M. These tumors are Ki67+, Nestin+, Olig2+, and largely GFAP− and can arise anywhere within the brainstem, including the classic DIPG location of the ventral pons. Expression of the H3.3K27M mutation reduces overall H3K27me3 as compared with tumors without the mutation, similar to what has been previously shown in human and mouse tumors. Thus, we have generated a novel genetically engineered mouse model of DIPG, which faithfully recapitulates the human disease and represents a novel platform with which to study the biology and treatment of this deadly disease.