RESUMEN
Cerebral creatine deficiency syndrome (CCDS) is an inborn error of metabolism characterized by intellectual delays, seizures, and autistic-like behavior. However, the role of endogenously synthesized creatine on CNS development and function remains poorly understood. Here, magnetic resonance spectroscopy of adult mouse brains from both sexes revealed creatine synthesis is dependent on the expression of the enzyme, guanidinoacetate methyltransferase (GAMT). To identify Gamt-expressed cells, and how Gamt affects postnatal CNS development, we generated a mouse line by knocking-in a GFP, which is expressed on excision of Gamt We found that Gamt is expressed in mature oligodendrocytes during active myelination in the developing postnatal CNS. Homozygous deletion of Gamt resulted in significantly reduced mature oligodendrocytes and delayed myelination in the corpus callosum. Moreover, the absence of endogenous creatine resulted in altered AMPK signaling in the brain, reduced brain creatine kinase expression in cortical neurons, and signs of axonal damage. Experimental demyelination in mice after tamoxifen-induced conditional deletion of Gamt in oligodendrocyte lineage cells resulted in delayed maturation of oligodendrocytes and myelin coverage in lesions. Moreover, creatine and cyclocreatine supplementation can enhance remyelination after demyelination. Our results suggest endogenously synthesized creatine controls the bioenergetic demand required for the timely maturation of oligodendrocytes during postnatal CNS development, and that delayed myelination and altered CNS energetics through the disruption of creatine synthesis might contribute to conditions, such as CCDS.SIGNIFICANCE STATEMENT Cerebral creatine deficiency syndrome is a rare disease of inborn errors in metabolism, which is characterized by intellectual delays, seizures, and autism-like behavior. We found that oligodendrocytes are the main source of endogenously synthesized creatine in the adult CNS, and the loss of endogenous creatine synthesis led to delayed myelination. Our study suggests impaired cerebral creatine synthesis affects the timing of myelination and may impact brain bioenergetics.
Asunto(s)
Enfermedades Desmielinizantes , Discapacidad Intelectual , Masculino , Femenino , Ratones , Animales , Creatina/metabolismo , Homocigoto , Eliminación de Secuencia , Oligodendroglía/metabolismo , Discapacidad Intelectual/genética , Enfermedades Desmielinizantes/patología , ConvulsionesRESUMEN
PURPOSE: In high-acuity situations such as cardiac arrest, clinicians rely on prepared medications stocked in code carts to provide timely and accurate pharmacotherapy. We examined shortage trends for medications commonly used in code carts. METHODS: Drug shortage data from 2001 to 2022 were retrieved from the University of Utah Drug Information Service (UUDIS) to characterize shortages reported for commonly used code cart medications. Data extracted included the number of shortages, shortage duration, drug characteristics, and reason for the shortage. RESULTS: From 2001 to 2022, 71 drug shortages for code cart medications were reported. The number of new shortages peaked in 2010, and the number of total shortages peaked in 2010. At the end of the study period, 61 (84.7%) shortages had been resolved. For resolved shortages, the mean shortage duration was 18.2 months. The drug with the greatest number of reported shortages was dextrose (10 total), the drug with the longest resolved shortage was calcium chloride injection (116 months), and the drug with the longest active shortage was atropine injection (165 months at the end of the study period). Throughout the entire study period, only 2 suppliers provided commercially available prefilled syringes of dextrose for stocking on code carts. The most common reason for shortages, when reported, was manufacturing delays. CONCLUSION: Medications commonly used in code carts were frequently impacted by drug shortages, which have the potential to impact patient care. Institutional protocols for mitigation and larger efforts to promote a more resilient drug supply chain are critical to ensure patient safety and quality care.