ABSTRACT
Modulating the abundance of the blood-brain barrier (BBB) efflux transporter breast cancer resistance protein (BCRP) has the potential to impact brain levels of drugs and endogenous substrates. Studies have demonstrated that the metal ionophore clioquinol (CQ) increases BBB abundance of P-glycoprotein (P-gp), an effect associated with increased endothelial cell levels of Cu2+. This study therefore assessed whether human brain endothelial (hCMEC/D3) cell abundance and function of BCRP is modulated by CQ. hCMEC/D3 cells were treated with CQ, Zn2+ and Cu2+ (CZC) (0.5 µM, 0.5 µM, 0.1 µM, respectively) for 24 h and BCRP mRNA and protein abundance was determined by Western blot and qPCR, respectively. After a series of optimisation studies assessing specificity of bodipy prazosin (BP) and Ko143 as a substrate and inhibitor of BCRP, respectively, the impact of CZC on BP uptake was assessed. While CZC did not increase mRNA expression of BCRP, BCRP abundance was increased 1.8 ± 0.1-fold; this was associated with a 68.1 ± 3.3% reduction in accumulation of BP in hCMEC/D3 cells. This is the first study to demonstrate that augmenting metal ion availability enhances protein abundance and function of BCRP at the BBB, which may be exploited to modulate CNS access of therapeutics and endogenous substrates.
Subject(s)
Breast Neoplasms , Clioquinol , Pharmaceutical Preparations , ATP Binding Cassette Transporter, Subfamily G, Member 2/genetics , ATP Binding Cassette Transporter, Subfamily G, Member 2/metabolism , Blood-Brain Barrier/metabolism , Brain/metabolism , Clioquinol/pharmacology , Copper , Endothelial Cells/metabolism , Female , Humans , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , ZincABSTRACT
BACKGROUND: Recent government initiatives in the NHS have seen patient care becoming increasingly target-driven. However, the impact of targets, particularly those based on a timeframe, have not been extensively studied, and concerns remain about unintended consequences for patients. The aim of this study was to evaluate the effect of a 4 h target in the Emergency Department (ED) on patient care and outcomes. METHODS: The study comprised an interrupted time-series regression analysis of anonymised patient-level data from 580,000 new patient episodes in the ED between April 2000 and Feb 2006. Outcomes were time in ED, time to clinician, mortality, admission and reattendance rates, and number of investigations. RESULTS: 90% target was associated with reductions in time in department and fewer patients admitted for less than 24 and 48 h, and a slight increase in the number reattending within 7 days. 98% target was associated with levelling-off of time in department and reductions in numbers admitted and reattending within 7 days. Neither target was associated with change in time to clinician. The introduction of a minor injuries unit (MIU) was associated with reductions in time to clinician and percentage not waiting, and increases in number of investigations, percentages admitted, admitted for 24 h and reattendances within 7 days. Mortality was unaffected by either target or MIU. CONCLUSION: Although time target introduction is associated with changes in patient care, the introduction of a co-located MIU had greater impact.
