On-Demand Activity: Oligodendroglia ensheath axons in the brain with myelin, which provides the insulation that speeds up transmission of neuronal electrical impulses. The process of myelination in the human brain goes on for decades, concurrent with all manner of brain development and cognitive activity. Gibson et al. (p. 10.1126/science.1252304 , published online 10 April; see the Perspective by Bechler and ffrench-Constant ) used optogenetics to study myelination in response to neural activity. Electrical activity in the motor cortex of the brain of awake mice led to proliferation and differentiation of oligodendrocytes and consequently increased myelination and alterations in motor response.

Diffuse midline gliomas (DMGs) are universally lethal malignancies occurring chiefly during childhood and involving midline structures of the central nervous system, including thalamus, pons, and spinal cord. These molecularly related cancers are characterized by high prevalence of the histone H3K27M mutation. In search of effective therapeutic options, we examined multiple DMG cultures in sequential quantitative high-throughput screens (HTS) of 2706 approved and investigational drugs. This effort generated 19,936 single-agent dose responses that inspired a series of HTS-enabled drug combination assessments encompassing 9195 drug-drug examinations. Top combinations were validated across patient-derived cell cultures representing the major DMG genotypes. In vivo testing in patient-derived xenograft models validated the combination of the multi–histone deacetylase (HDAC) inhibitor panobinostat and the proteasome inhibitor marizomib as a promising therapeutic approach. Transcriptional and metabolomic surveys revealed substantial alterations to key metabolic processes and the cellular unfolded protein response after treatment with panobinostat and marizomib. Mitigation of drug-induced cytotoxicity and basal mitochondrial respiration with exogenous application of nicotinamide mononucleotide (NMN) or exacerbation of these phenotypes when blocking nicotinamide adenine dinucleotide (NAD⁺) production via nicotinamide phosphoribosyltransferase (NAMPT) inhibition demonstrated that metabolic catastrophe drives the combination-induced cytotoxicity. This study provides a comprehensive single-agent and combinatorial drug screen for DMG and identifies concomitant HDAC and proteasome inhibition as a promising therapeutic strategy that underscores underrecognized metabolic vulnerabilities in DMG.

The upcoming transition of the United States Medical Licensing Examination Step 1 to pass/fail score reporting has wide-ranging implications for the medical education community. The decision to discontinue 3-digit numeric score reporting comes following advocacy to change the exam because of its disproportionate importance in the residency match process, the negative impact the exam has on student well-being, and the prominent influence the exam has on medical school curricula. Shifting to pass/fail score reporting for Step 1 creates significant uncertainties to be addressed by the stakeholders in the transition from undergraduate medical education to graduate medical education. In this Invited Commentary, the authors reflect on the positive implications of this scoring change, potential negative ramifications that need to be proactively addressed, and future ways that the transition to residency can be optimized. The transition to pass/fail score reporting for Step 1 creates an opportunity to redefine the residency match process, to support applicant decision making, and to encourage a holistic review of applicants. These changes to the review process will require grace and trust among stakeholders, including students, as well as active support for students who might be negatively impacted during a complex implementation phase. By removing the dominance of Step 1 numeric scores from the residency selection process, the change to pass/fail scoring provides a unique opportunity for all stakeholders to work together and redefine the transition to residency while protecting students from unintended negative consequences.

Diffuse Intrinsic Pontine Glioma (DIPG) is a childhood brainstem tumor that carries a universally fatal prognosis. Because surgical resection is not a viable treatment strategy and biopsy is not routinely performed, the availability of patient samples for research is limited. Consequently, efforts to study this disease have been challenged by a paucity of faithful disease models. To address this need, we describe here a protocol for the rapid processing of post-mortem autopsy tissue samples in order to generate durable patient-derived cell culture models that can be used in in vitro assays or in vivo orthotopic xenograft experiments. These models can be used to screen for potential drug targets and to study fundamental pathobiological processes within DIPG. This protocol can further be extended to analyze and isolate tumor and microenvironmental cells using Fluorescence-activated Cell Sorting (FACS), which enables subsequent analysis of gene expression, protein expression, or epigenetic modifications of DNA at the bulk cell or single cell level. Finally, this protocol can also be adapted to generate patient-derived cultures for other central nervous system tumors.

This Viewpoint discusses the actions resident physicians and fellows are increasingly taking through labor unions to counteract physician burnout, improve health care equity, and reprioritize the patient-physician relationship.