Long γ-ray bursts (GRBs) are the most dramatic examples of massive stellar deaths, often associated with supernovae. They release ultra-relativistic jets, which produce non-thermal emission through synchrotron radiation as they interact with the surrounding medium. Here we report observations of the unusual GRB 101225A. Its γ-ray emission was exceptionally long-lived and was followed by a bright X-ray transient with a hot thermal component and an unusual optical counterpart. During the first 10 days, the optical emission evolved as an expanding, cooling black body, after which an additional component, consistent with a faint supernova, emerged. We estimate its redshift to be z = 0.33 by fitting the spectral-energy distribution and light curve of the optical emission with a GRB-supernova template. Deep optical observations may have revealed a faint, unresolved host galaxy. Our proposed progenitor is a merger of a helium star with a neutron star that underwent a common envelope phase, expelling its hydrogen envelope. The resulting explosion created a GRB-like jet which became thermalized by interacting with the dense, previously ejected material, thus creating the observed black body, until finally the emission from the supernova dominated. An alternative explanation is a minor body falling onto a neutron star in the Galaxy.
The aim of this study was to show the benefits of combining therapeutic drug monitoring (TDM) and pharmacogenetic analyses to optimize efavirenz (EFV) therapy. Patients were selected to minimize nongenetic differences between patients: 32 HIV adherent patients without drug interactions treated with an EFV nonindividualized dose over at least 1 year and included in a TDM program were genotyped according to minimum steady-state concentrations (C ss min). The EFV plasma concentrations (n = 158) were quantified by high-performance liquid chromatography-ultraviolet, and genetic polymorphisms were analyzed using the PHARMAchip. Central nervous system side effects were assessed systematically. Genetic polymorphisms were detected in 79.2% of patients with EFV Css min outside the therapeutic range (1-4 mg/L), showing the high diagnostic efficacy of combining TDM with pharmacogenetic testing. CYP2B6 (516 G>T) polymorphisms were associated with a significant decrease in EFV plasma clearance in 80% of the poor metabolizer patients (G/T, T/T). All homozygous patients had C ss min greater than 4 mg/L, 75% of them showing central nervous system side effects. For such patients, pharmacogenetic testing with TDM could be advantageous because the polymorphism is a determinant of these circumstances and TDM would allow reductions in dose to be specified without assuming an equal dose for any given genotype. In fact, poor metabolizer patients required less than a 600 mg standard starting dose, implying that if CYP2B6 screening were available, EFV therapy could be started at 400 mg and later TDM-individualized. The results of this study clarify the genotype versus phenotype debate for optimizing drug therapy. Pharmacogenetic testing together with TDM links genotype to phenotypic differences in drug concentrations and adverse events, providing additional support for dosage adjustment and a more efficient use of both approaches. As genotype screens become cheaper, and in combination with TDM, adjusting dosages in the light of genetic polymorphisms will become a reality.
The Acknowledgements of this Letter should have included the following line: ''We thank A. J. Castro-Tirado for help in obtaining the data from the BTA 6-m telescope and comments on an early draft.'' This has been added to the PDF and HTML versions online.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.