Contribution of organic anion-transporting polypeptides 1a/1b to doxorubicin uptake and clearance

The organic anion-transporting polypeptides represent an important family of drug uptake transporters that mediate the cellular uptake of a broad range of substrates including numerous drugs. Doxorubicin is a highly efficacious and well-established anthracycline chemotherapeutic agent commonly used in the treatment of a wide range of cancers. Although doxorubicin is a known substrate for efflux transporters such as P-glycoprotein (P-gp; MDR1, ABCB1), significantly less is known regarding its interactions with drug uptake transporters. Here, we investigated the role of organic anion transporting polypeptide (OATP) transporters to the disposition of doxorubicin. A recombinant vaccinia-based method for expressing uptake transporters in HeLa cells revealed that OATP1A2, but not OATP1B1 or OATP1B3, and the rat ortholog Oatp1a4 were capable of significant doxorubicin uptake. Interestingly, transwell assays using Madin-Darby canine kidney II cell line cells stably expressing specific uptake and/or efflux transporters revealed that OATP1B1, OATP1B3, and OATP1A2, either alone or in combination with MDR1, significantly transported doxorubicin. An assessment of polymorphisms in SLCO1A2 revealed that four variants were associated with significantly impaired doxorubicin transport in vitro. In vivo doxorubicin disposition studies revealed that doxorubicin plasma area under the curve was significantly higher (1.7-fold) in Slco1a/1b-/- versus wild-type mice. The liver-to-plasma ratio of doxorubicin was significantly decreased (2.3-fold) in Slco1a/1b2-/- mice and clearance was reduced by 40% compared with wild-type mice, suggesting Oatp1b transporters are important for doxorubicin hepatic uptake. In conclusion, we demonstrate important roles for OATP1A/1B in transporter mediated uptake and disposition of doxorubicin

Phase I and Phase II Therapies for Acute Ischemic Stroke: An Update on Currently Studied Drugs in Clinical Research.

Acute ischemic stroke is a devastating cause of death and disability, consequences of which depend on the time from ischemia onset to treatment, the affected brain region, and its size. The main targets of ischemic stroke therapy aim to restore tissue perfusion in the ischemic penumbra in order to decrease the total infarct area by maintaining blood flow. Advances in research of pathological process and pathways during acute ischemia have resulted in improvement of new treatment strategies apart from restoring perfusion. Additionally, limiting the injury severity by manipulating the molecular mechanisms during ischemia has become a promising approach, especially in animal research. The purpose of this article is to review completed and ongoing phases I and II trials for the treatment of acute ischemic stroke, reviewing studies on antithrombotic, thrombolytic, neuroprotective, and antineuroinflammatory drugs that may translate into more effective treatments

Solid-state metathesis reactions under pressure: A rapid route to crystalline gallium nitride

High pressure chemistry has traditionally involved applying pressure and increasing temperature until conditions become thermodynamically favorable for phase transitions or reactions to occur. Here, high pressure alone is used as a starting point for carrying out rapid, self-propagating metathesis reactions. By initiating chemical reactions under pressure, crystalline phases, such as gallium nitride, can be synthesized which are inaccessible when initiated from ambient conditions. The single-phase gallium nitride made by metathesis reactions under pressure displays significant photoluminescence intensity in the blue/ultraviolet region. The absence of size or surface-state effects in the photoluminescence spectra show that the crystallites are of micron dimensions. The narrow lines of the x-ray diffraction patterns and scanning electron microscopy confirm this conclusion. Brightly luminescent thin films can be readily grown using pulsed laser deposition

Contribution of hepatic organic anion-transporting polypeptides to docetaxel uptake and clearance

The antimicrotubular agent docetaxel is a widely used chemotherapeutic drug for the treatment of multiple solid tumors and is predominantly dependent on hepatic disposition. In this study, we evaluated drug uptake transporters capable of transporting radiolabeled docetaxel. By screening an array of drug uptake transporters in HeLa cells using a recombinant vacciniabased method, five organic anion-transporting polypeptides (OATP) capable of docetaxel uptake were identified: OATP1A2, OATP1B1, OATP1B3, OATP1C1, and Oatp1b2. Kinetic analysis of docetaxel transport revealed similar kinetic parameters among hepatic OATP1B/1b transporters. An assessment of polymorphisms (SNPs) in SLCO1B1 and SLCO1B3 revealed that a number of OATP1B1 and OATP1B3 variants were associated with impaired docetaxel transport. A Transwell-based vectorial transport assay using MDCKII stable cells showed that docetaxel was transported significantly into the apical compartment of double-transfected (MDCKII-OATP1B1/MDR1 and MDCKII-OATP1B3/MDR1) cells compared with singletransfected (MDCKII-OATP1B1 and MDCKII-OATP1B3) cells (P \u3c 0.05) or control (MDCKII-Co) cells (P \u3c 0.001). In vivo docetaxel transport studies in Slco1b2-/- mice showed approximately \u3e5.5-fold higher plasma concentrations (P \u3c 0.01) and approximately 3-fold decreased liver-to-plasma ratio (P \u3c 0.05) of docetaxel compared with wild-type (WT) mice. The plasma clearance of docetaxel in Slco1b2-/- mice was 83% lower than WT mice (P \u3c 0.05). In conclusion, this study demonstrates the important roles of OATP1B transporters to the hepatic disposition and clearance of docetaxel, and supporting roles of these transporters for docetaxel pharmacokinetics

Interaction of three regiospecific amino acid residues is required for OATP1B1 gain of OATP1B3 substrate specificity

The human organic anion-transporting polypeptides OATP1B1 (SLCO1B1) and OATP1B3 (SLCO1B3) are liver-enriched membrane transporters of major importance to hepatic uptake of numerous endogenous compounds, including bile acids, steroid conjugates, hormones, and drugs, including the 3-hydroxy-3- methylglutaryl Co-A reductase inhibitor (statin) family of cholesterol-lowering compounds. Despite their remarkable substrate overlap, there are notable exceptions: in particular, the gastrointestinal peptide hormone cholecystokinin-8 (CCK-8) is a high affinity substrate for OATP1B3 but not OATP1B1. We utilized homologous recombination of linear DNA by E. coli to generate a library of cDNA containing monomer size chimeric OATP1B1-1B3 and OATP1B3-1B1 transporters with randomly distributed chimeric junctions to identify three discrete regions of the transporter involved in conferring CCK-8 transport activity. Site-directed mutagenesis of three key residues in OATP1B1 transmembrane helices 1 and 10, and extracellular loop 6, to the corresponding residues in OATP1B3, resulted in a gain of CCK-8 transport by OATP1B1. The residues appear specific to CCK-8, as the mutations did not affect transport of the shared OATP1B substrate atorvastatin or the OATP1B1-specific substrate estrone sulfate. Regions involved in gain of CCK-8 transport by OATP1B1, when mapped to the crystal structures of bacterial transporters from the major facilitator superfamily, are positioned to suggest these regions could readily interact with drug substrates. Accordingly, our data provide new insight into the molecular determinants of the substrate specificity of these hepatic uptake transporters with relevance to targeted drug design and prediction of drug-drug interactions. © 2012 American Chemical Society

Dynamic Sulfur Tolerant Process and System with Inline Acid Gas-Selective Removal for Generating Hydrogen for Fuel Cells

This invention relates to a sulfur tolerant, dynamic, compact, lightweight fuel process and system that is capable of converting sulfur bearing carbonaceous fuels to hydrogen rich gases suitable for fuel cells or chemical processing applications. The process and system is based on the AHR and WGS reactions, followed by cleanup of byproduct sulfur-containing gases and carbon oxides that would otherwise poison the fuel cell electrocatalyst. Advantageously, this is accomplished via an ASMS and a methanator or an AWMR. The process and system preferably uses a special sulfur tolerant catalysts and hardware designs that enable the conversion in an energy efficient manner while maintaining desirable performance characteristics such as rapid start-stop and fast response to load change capabilities

From Fair Decision Making to Social Equality

The study of fairness in intelligent decision systems has mostly ignored long-term influence on the underlying population. Yet fairness considerations (e.g. affirmative action) have often the implicit goal of achieving balance among groups within the population. The most basic notion of balance is eventual equality between the qualifications of the groups. How can we incorporate influence dynamics in decision making? How well do dynamics-oblivious fairness policies fare in terms of reaching equality? In this paper, we propose a simple yet revealing model that encompasses (1) a selection process where an institution chooses from multiple groups according to their qualifications so as to maximize an institutional utility and (2) dynamics that govern the evolution of the groups' qualifications according to the imposed policies. We focus on demographic parity as the formalism of affirmative action. We then give conditions under which an unconstrained policy reaches equality on its own. In this case, surprisingly, imposing demographic parity may break equality. When it doesn't, one would expect the additional constraint to reduce utility, however, we show that utility may in fact increase. In more realistic scenarios, unconstrained policies do not lead to equality. In such cases, we show that although imposing demographic parity may remedy it, there is a danger that groups settle at a worse set of qualifications. As a silver lining, we also identify when the constraint not only leads to equality, but also improves all groups. This gives quantifiable insight into both sides of the mismatch hypothesis. These cases and trade-offs are instrumental in determining when and how imposing demographic parity can be beneficial in selection processes, both for the institution and for society on the long run.Comment: Short version appears in the proceedings of ACM FAT* 201

Polymorphic variants in the human bile salt export pump (BSEP; ABCB11): Functional characterization and interindividual variability

OBJECTIVES: Our aims were to identify and functionally characterize coding region nonsynonymous single nucleotide polymorphisms in the hepatic efflux transporter, bile salt export pump (BSEP; ABCB11), and to assess interindividual variability in BSEP expression. METHODS: We identified 24 single nucleotide polymorphisms, including nine nonsynonymous variants, in ABCB11 from genomic DNA of ∼250 ethnically diverse healthy individuals using denaturing high-performance liquid chromatography analysis and DNA sequencing. Wild type and variant BSEP were generated and functionally characterized for taurocholate transport activity in vitro in HeLa cells using a recombinant vaccinia-based method. BSEP expression was assessed by real-time mRNA analysis, western blot analysis, and immunofluorescence confocal microscopy. RESULTS: For the most part, polymorphisms were rare and ethnic-dependent. In vitro functional studies revealed several rare variants, including 616A\u3eG, 1674G\u3eC, 1772A\u3eG, and 3556G\u3eA, to be associated with significantly impaired taurocholate transport activity while the 890A\u3eG variant trended towards impaired function but was not statistically significant. The 3556G\u3eA variant was associated with reduced cell surface to total protein expression compared with wild-type BSEP. Expression of BSEP by mRNA and protein analysis was determined from a bank of human liver samples. Wide interindividual variability was noted in both mRNA (19-fold) and protein (31-fold) expression levels. The common variant 1331T\u3eC was associated with significantly reduced hepatic BSEP mRNA levels. CONCLUSION: Accordingly, our study indicates there are functionally relevant polymorphisms in ABCB11 which may be of potential relevance in the predisposition to acquired liver disorders such as drug-induced cholestasis. © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins

Cathelicidin preserves intestinal barrier function in polymicrobial sepsis.

ObjectivesThe intestinal epithelium compartmentalizes the sterile bloodstream and the commensal bacteria in the gut. Accumulating evidence suggests that this barrier is impaired in sepsis, aggravating systemic inflammation. Previous studies reported that cathelicidin is differentially expressed in various tissues in sepsis. However, its role in sepsis-induced intestinal barrier dysfunction has not been investigated.DesignTo examine the role of cathelicidin in polymicrobial sepsis, cathelicidin wild-(Cnlp+/+) and knockout (Cnlp-/-) mice underwent cecal-ligation and puncture (CLP) followed by the assessment of septic mortality and morbidity as well as histological, biochemical, immunological, and transcriptomic analyses in the ileal tissues. We also evaluated the prophylactic and therapeutic efficacies of vitamin D3 (an inducer of endogenous cathelicidin) in the CLP-induced murine polymicrobial sepsis model.ResultsThe ileal expression of cathelicidin was increased by three-fold after CLP, peaking at 4 h. Knockout of Cnlp significantly increased 7-day mortality and was associated with a higher murine sepsis score. Alcian-blue staining revealed a reduced number of mucin-positive goblet cells, accompanied by reduced mucin expression. Increased number of apoptotic cells and cleavage of caspase-3 were observed. Cnlp deletion increased intestinal permeability to 4kD fluorescein-labeled dextran and reduced the expression of tight junction proteins claudin-1 and occludin. Notably, circulating bacterial DNA load increased more than two-fold. Transcriptome analysis revealed upregulation of cytokine/inflammatory pathway. Depletion of Cnlp induced more M1 macrophages and neutrophils compared with the wild-type mice after CLP. Mice pre-treated with cholecalciferol (an inactive form of vitamin D3) or treated with 1alpha, 25-dihydroxyvitamin D3 (an active form of VD3) had decreased 7-day mortality and significantly less severe symptoms. Intriguingly, the administration of cholecalciferol after CLP led to worsened 7-day mortality and the associated symptoms.ConclusionsEndogenous cathelicidin promotes intestinal barrier integrity accompanied by modulating the infiltration of neutrophils and macrophages in polymicrobial sepsis. Our data suggested that 1alpha, 25-dihydroxyvitamin D3 but not cholecalciferol is a potential therapeutic agent for treating sepsis