A system for exposing molecules and cells to biologically relevant and accurately controlled steady-state concentrations of nitric oxide and oxygen

Nitric oxide (NO) plays key roles in cell signaling and physiology, with diverse functions mediated by NO concentrations varying over three orders-of-magnitude. In spite of this critical concentration dependence, current approaches to NO delivery in vitro result in biologically irrelevant and poorly controlled levels, with hyperoxic conditions imposed by ambient air. To solve these problems, we developed a system for controlled delivery of NO and O[subscript 2] over large concentration ranges to mimic biological conditions. Here we describe the fabrication, operation and calibration of the delivery system. We then describe applications for delivery of NO and O[subscript 2] into cell culture media, with a comparison of experimental results and predictions from mass transfer models that predict the steady-state levels of various NO-derived reactive species. We also determined that components of culture media do not affect the steady-state levels of NO or O[subscript 2] in the device. This system provides critical control of NO delivery for in vitro models of NO biology and chemistry.National Cancer Institute (U.S.) (CA026731)National Cancer Institute (U.S.) (CA116318)National Institute of Environmental Health Sciences (ES002109

Review of microdialysis in brain tumors, from concept to application: First Annual Carolyn Frye-Halloran Symposium

In individuals with brain tumors, pharmacodynamic and pharmacokinetic studies of therapeutic agents have historically used analyses of drug concentrations in serum or cerebrospinal fluid, which unfortunately do not necessarily reflect concentrations within the tumor and adjacent brain. This review article introduces to neurological and medical oncologists, as well as pharmacologists, the application of microdialysis in monitoring drug metabolism and delivery within the fluid of the interstitial space of brain tumor and its surroundings. Microdialysis samples soluble molecules from the extracellular fluid via a semipermeable membrane at the tip of a probe. In the past decade, it has been used predominantly in neurointensive care in the setting of brain trauma, vasospasm, epilepsy, and intracerebral hemorrhage. At the first Carolyn Frye-Halloran Symposium held at Massachusetts General Hospital in March 2002, the concept of microdialysis was extended to specifically address its possible use in treating brain tumor patients. In doing so we provide a rationale for the use of this technology by a National Cancer Institute consortium, New Approaches to Brain Tumor Therapy, to measure levels of drugs in brain tissue as part of phase 1 trials. Originally published Neuro-oncology, Vol. 6, No. 1, Jan 200

Integrated mapping of pharmacokinetics and pharmacodynamics in a patient-derived xenograft model of glioblastoma

Therapeutic options for the treatment of glioblastoma remain inadequate despite concerted research efforts in drug development. Therapeutic failure can result from poor permeability of the blood-brain barrier, heterogeneous drug distribution, and development of resistance. Elucidation of relationships among such parameters could enable the development of predictive models of drug response in patients and inform drug development. Complementary analyses were applied to a glioblastoma patient-derived xenograft model in order to quantitatively map distribution and resulting cellular response to the EGFR inhibitor erlotinib. Mass spectrometry images of erlotinib were registered to histology and magnetic resonance images in order to correlate drug distribution with tumor characteristics. Phosphoproteomics and immunohistochemistry were used to assess protein signaling in response to drug, and integrated with transcriptional response using mRNA sequencing. This comprehensive dataset provides simultaneous insight into pharmacokinetics and pharmacodynamics and indicates that erlotinib delivery to intracranial tumors is insufficient to inhibit EGFR tyrosine kinase signaling.National Institutes of Health (U.S.) (U54 CA210180)MIT/Mayo Physical Sciences Center for Drug Distribution and Drug Efficacy in Brain TumorsDana-Farber Cancer Institute (PLGA Fund)Lundbeck FoundationNovo Nordisk Foundatio

Abcg2/Bcrp1 mediates the polarized transport of antiretroviral nucleosides abacavir and zidovudine,” Drug Metabolism and Disposition: The Biological Fate of Chemicals

ABSTRACT: The bioavailability and targeted distribution of abacavir (ABC) and zidovudine (AZT) to viral reservoirs may be influenced by efflux transporters. The purpose of this study was to characterize the interaction of these nucleoside reverse transcriptase inhibitors with the Abcg2/Bcrp1 transporter, the murine homolog of human breast cancer resistance protein (BCRP), using a Bcrp1-trans