91 research outputs found
Making and breaking order via clothing Clothing regulation, cross-dressing, and the ordering mentality in later medieval and early modern England
Following the events which disrupted social stability in fourteenth and fifteenth-century England, individuals from a variety of social contexts demonstrated a particular necessity to see order visibly displayed in society. This thesis examines sumptuary regulations and cross-dressing side by side to demonstrate clothing's relationship to both making and breaking order. In the act of revealing this relationship, this thesis will argue that the two cases demonstrate clothing’s importance in creating a visible confirmation of social order which ultimately brings to the surface an underlying collective ordering mentality that equated a sense of security with arranging everyone in society in their rightful place
Developmental patterns in human blood–brain barrier and blood–cerebrospinal fluid barrier ABC drug transporter expression
When drugs exert their effects in the brain, linear extrapolation of doses from adults could be harmful for children as the blood–brain barrier (BBB) and blood–CSF barrier (BCSFB) function is still immature. More specifically, age-related variation in membrane transporters may impact brain disposition. As human data on brain transporter expression is scarce, age dependent [gestational age (GA), postnatal age (PNA), and postmenstrual age (PMA)] variation in immunohistochemical localization and staining intensity of the ABC transporters P-glycoprotein (Pgp), breast cancer resistance protein (BCRP), and multidrug resistance-associated proteins 1, 2, 4, and 5 (MRP1/2/4/5) was investigated. Post mortem brain cortical and ventricular tissue was derived from 23 fetuses (GA range 12.9–39 weeks), 17 neonates (GA range 24.6–41.3 weeks, PNA range 0.004–3.5 weeks), 8 children (PNA range 0.1–3 years), and 4 adults who died from a wide variety of underlying conditions. In brain cortical BBB, immunostaining increased with age for Pgp and BCRP, while in contrast, MRP1 and MRP2 staining intensity appeared higher in fetuses, neonates, and children, as compared to adults. BCSFB was positively stained for Pgp, MRP1, and MRP2 and appeared stable across age, while BCRP was not detected. MRP4 and MRP5 were not det
Multipole interaction between atoms and their photonic environment
Macroscopic field quantization is presented for a nondispersive photonic
dielectric environment, both in the absence and presence of guest atoms.
Starting with a minimal-coupling Lagrangian, a careful look at functional
derivatives shows how to obtain Maxwell's equations before and after choosing a
suitable gauge. A Hamiltonian is derived with a multipolar interaction between
the guest atoms and the electromagnetic field. Canonical variables and fields
are determined and in particular the field canonically conjugate to the vector
potential is identified by functional differentiation as minus the full
displacement field. An important result is that inside the dielectric a dipole
couples to a field that is neither the (transverse) electric nor the
macroscopic displacement field. The dielectric function is different from the
bulk dielectric function at the position of the dipole, so that local-field
effects must be taken into account.Comment: 17 pages, to be published in Physical Review
On a coupled PDE model for image restoration
In this paper, we consider a new coupled PDE model for image restoration.
Both the image and the edge variables are incorporated by coupling them into
two different PDEs. It is shown that the initial-boundary value problem has
global in time dissipative solutions (in a sense going back to P.-L. Lions),
and several properties of these solutions are established. This is a rough
draft, and the final version of the paper will contain a modelling part and
numerical experiments
Interaction of nonsteroidal anti-inflammatory drugs with multidrug resistance protein (MRP) 2/ABCC2- and MRP4/ABCC4-mediated methotrexate transport.
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34599.pdf (publisher's version ) (Open Access)Methotrexate (MTX) has been used in combination with nonsteroidal anti-inflammatory drugs (NSAIDs) in the treatment of inflammatory diseases as well as malignancies. Especially at high MTX dosages, severe adverse effects with this combination may occur, usually resulting from an impaired renal elimination. It has been shown that the mechanism of this interaction cannot be fully attributed to inhibition of basolateral MTX uptake in renal proximal tubules. Here, we studied the effect of various NSAIDs on MTX transport in membrane vesicles isolated from cells overexpressing the proximal tubular apical efflux transporters human multidrug resistance protein (MRP) 2/ABCC2 and MRP4/ABCC4. MTX was transported by MRP2 and MRP4 with Km values of 480 +/- 90 and 220 +/- 70 microM, respectively. The inhibitory potency of the NSAIDs was generally higher against MRP4- than MRP2-mediated MTX transport, with therapeutically relevant IC50 values, ranging from approximately 2 microM to 1.8 mM. Salicylate, piroxicam, ibuprofen, naproxen, sulindac, tolmetin, and etodolac inhibited MRP2- and MRP4-mediated MTX transport according to a one-site competition model. In some cases, more complex interaction patterns were observed. Inhibition of MRP4 by diclofenac and MRP2 by indomethacin and ketoprofen followed a two-site competition model. Phenylbutazone stimulated MRP2 and celecoxib MRP4 transport at low concentrations and inhibited both transporters at high concentration. Our data suggest that the inhibition by NSAIDs of renal MTX efflux via MRP2 and MRP4 is a potential new site and mechanism contributing to the overall interaction between these drugs
Multidrug resistance protein 4 (MRP4/ABCC4): a versatile efflux transporter for drugs and signalling molecules.
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70675.pdf (publisher's version ) (Closed access)Multidrug resistance protein (MRP) 4 is a member of the MRP/ABCC subfamily of ATP-binding cassette transporters, which are capable of pumping a wide variety of endogenous and xenobiotic organic anionic compounds out of the cell. In addition to its role in the body distribution and renal excretion of a wide variety of antiviral, cytostatic, antibiotic and cardiovascular drugs, MRP4/ABCC4 has the remarkable ability to transport molecules involved in cellular signalling. These molecules include cyclic nucleotides, eicosanoids, urate and conjugated steroids. The unique structure, regulation and dual localisation of MRP4 in polarised cells could be connected with a key function in cellular protection and extracellular signalling pathways. This review focuses on recent insights into the versatile transport function of MRP4 and its potential as a new therapeutic target to modulate various pathophysiological signalling processes.8 p
PfMDR2 and PfMDR5 are dispensable for Plasmodium falciparum asexual parasite multiplication but change in vitro susceptibility to anti-malarial drugs
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153635.pdf (publisher's version ) (Open Access)BACKGROUND: Membrane-associated ATP binding cassette (ABC) transport proteins hydrolyze ATP in order to translocate a broad spectrum of substrates, from single ions to macromolecules across membranes. In humans, members from this transport family have been linked to drug resistance phenotypes, e.g., tumour resistance by enhanced export of chemotherapeutic agents from cancer cells due to gene amplifications or polymorphisms in multidrug resistance (MDR) protein 1. Similar mechanisms have linked the Plasmodium falciparum PfMDR1 transporter to anti-malarial drug resistance acquisition. In this study, the possible involvement of two related MDR proteins, PfMDR2 and PfMDR5, to emerging drug resistance is investigated by a reverse genetics approach. METHODS: A homologous double crossover strategy was used to generate P. falciparum parasites lacking the Pfmdr2 (PfDeltamdr2) or Pfmdr5 (PfDeltamdr5) gene. Plasmodium lactate dehydrogenase activity was used as read-out for sensitivity to artemisinin (ART), atovaquone (ATO), dihydroartemisinin (DHA), chloroquine (CQ), lumefantrine (LUM), mefloquine (MQ), and quinine (QN). Differences in half maximal inhibitory concentration (IC(5)(0)) values between wild type and each mutant line were determined using a paired t-test. RESULTS: Both PfDeltamdr2 and PfDeltamdr5 clones were capable of asexual multiplication. Upon drug exposure, PfDeltamdr2 showed a marginally decreased sensitivity to ATO (IC(5)(0) of 1.2 nM to 1.8 nM), MQ (124 nM to 185 nM) and QN (40 nM to 70 nM), as compared to wild type (NF54) parasites. On the other hand, PfDeltamdr5 showed slightly increased sensitivity to ART (IC(5)(0) of 26 nM to 19 nM). CONCLUSION: Both Pfmdr2 and Pfmdr5 are dispensable for blood stage development while the deletion lines show altered sensitivity profiles to commonly used anti-malarial drugs. The findings show for the first time that next to PfMDR2, the PfMDR5 transport protein could play a role in emerging drug resistance
Oxidative stress in malaria and artemisinin combination therapy: Pros and Cons
Artemisinin-based combination therapy (ACT) has been adopted as a strategy to mitigate multidrug resistance to antimalarial monotherapies. ACT combines the rapid and effective but rather short plasma half-life antimalarial action of an artemisinin derivative with a longer acting partner drug. Although the exact mechanisms of action of artemisinins are not well understood, several studies have proposed multiple cellular targets of artemisinins with involvement of reactive oxygen species (ROS). Most of the currently used ACT partner drugs are also known to involve ROS production in their mechanisms of action. This review gives a brief account of the oxidative stress and redox systems in malaria and discusses the context of antimalarial effectiveness of different ACTs compared with monotherapies of the partner drugs. A final account on the Pros and Cons of ACT as a strategy is discussed
Electrophysiological analysis of the mutated Na,K-ATPase cation binding pocket.
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142631.pdf (Publisher’s version ) (Open Access)Na,K-ATPase mediates net electrogenic transport by extruding three Na+ ions and importing two K+ ions across the plasma membrane during each reaction cycle. We mutated putative cation coordinating amino acids in transmembrane hairpin M5-M6 of rat Na,K-ATPase: Asp776 (Gln, Asp, Ala), Glu779 (Asp, Gln, Ala), Asp804 (Glu, Asn, Ala), and Asp808 (Glu, Asn, Ala). Electrogenic cation transport properties of these 12 mutants were analyzed in two-electrode voltage-clamp experiments on Xenopus laevis oocytes by measuring the voltage dependence of K+-stimulated stationary currents and pre-steady-state currents under electrogenic Na+/Na+ exchange conditions. Whereas mutants D804N, D804A, and D808A hardly showed any Na+/K+ pump currents, the other constructs could be classified according to the [K+] and voltage dependence of their stationary currents; mutants N776A and E779Q behaved similarly to the wild-type enzyme. Mutants E779D, E779A, D808E, and D808N had in common a decreased apparent affinity for extracellular K+. Mutants N776Q, N776D, and D804E showed large deviations from the wild-type behavior; the currents generated by mutant N776D showed weaker voltage dependence, and the current-voltage curves of mutants N776Q and D804E exhibited a negative slope. The apparent rate constants determined from transient Na+/Na+ exchange currents are rather voltage-independent and at potentials above -60 mV faster than the wild type. Thus, the characteristic voltage-dependent increase of the rate constants at hyperpolarizing potentials is almost absent in these mutants. Accordingly, dislocating the carboxamide or carboxyl group of Asn776 and Asp804, respectively, decreases the extracellular Na+ affinity
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