In Vivo Fluorine Imaging Using 1.5 Tesla MRI for Depiction of Experimental Myocarditis in a Rodent Animal Model.

The usefulness of perfluorocarbon nanoemulsions for the imaging of experimental myocarditis has been demonstrated in a high-field 9.4 Tesla MRI scanner. Our proof-of-concept study investigated the imaging capacity of PFC-based F/H MRI in an animal myocarditis model using a clinical field strength of 1.

Design of Nanohydrogels for Targeted Intracellular Drug Transport to the Trans-Golgi Network.

Nanohydrogels combine advantages of hydrogels and nanoparticles. In particular, they represent promising drug delivery systems. Nanogel synthesis by oxidative condensation of polyglycidol prepolymers, that are modified with thiol groups, results in crosslinking by disulfide bonds.

Evaluation of the Influence of Biosurface Design on the Interaction between the Regulatory Peptide RS1-reg and ODC1 Reveals a Membrane-Dependent Affinity Increase.

The regulatory solute carrier protein, family 1, member 1 (RS1) modulates via its N-terminal domain RS1-reg the activity of Na -d-glucose cotransporter 1 (SGLT1) and thereby the glucose uptake in the small intestine by blocking the release of SGLT1-containing vesicles at the trans-Golgi network (TGN). The antidiabetic activity of RS1 is mediated by ornithindecarboxylase 1 (ODC1), catalyzing the conversion of ornithine to putrescine. Putrescine can bind to a buddying protein complex for SGLT1-containing vesicles at the membrane of the TGN, triggering vesicle release.

TEMPO/TCC as a Chemo Selective Alternative for the Oxidation of Hyaluronic Acid.

Hyaluronic acid (HA)-based hydrogels are very commonly applied as cell carriers for different approaches in regenerative medicine. HA itself is a well-studied biomolecule that originates from the physiological extracellular matrix (ECM) of mammalians and, due to its acidic polysaccharide structure, offers many different possibilities for suitable chemical modifications which are necessary to control, for example, network formation. Most of these chemical modifications are performed using the free acid function of the polymer and, additionally, lead to an undesirable breakdown of the biopolymer's backbone.

Polyoxazolines with a Vicinally Double-Bioactivated Terminus for Biomacromolecular Affinity Assessment.

Interactions between proteins and carbohydrates with larger biomacromolecules, e.g., lectins, are usually examined using self-assembled monolayers on target gold surfaces as a simplified model measuring setup.

Rat Organic Cation Transporter 1 Contains Three Binding Sites for Substrate 1-Methyl-4-phenylpyridinium per Monomer.

Organic cation transporters OCT1 () and OCT2 () are critically involved in absorption and excretion of diverse cationic drugs. Because drug-drug interactions at these transporters may induce adverse drug effects in patients, in vitro testing during drug development for interaction with the human transporters is mandatory. Recent data performed with rat OCT1 (rOCT1) suggest that currently performed in vitro tests assuming one polyspecific binding site are insufficient.

A Modified Tripeptide Motif of RS1 () Down-Regulates Exocytotic Pathways of Human Na-d-glucose Cotransporters SGLT1, SGLT2, and Glucose Sensor SGLT3 in the Presence of Glucose.

A domain of protein RS1 () called RS1-Reg down-regulates the plasma membrane abundance of Na-d-glucose cotransporter SGLT1 by blocking the exocytotic pathway at the -Golgi. This effect is blunted by intracellular glucose but prevails when serine in a QSP (Gln-Ser-Pro) motif is replaced by glutamate [RS1-Reg(S20E)]. RS1-Reg binds to ornithine decarboxylase (ODC) and inhibits ODC in a glucose-dependent manner.

Protein RS1 (RSC1A1) Downregulates the Exocytotic Pathway of Glucose Transporter SGLT1 at Low Intracellular Glucose via Inhibition of Ornithine Decarboxylase.

Na-d-glucose cotransporter 1 (SGLT1) is rate-limiting for glucose absorption in the small intestine. Shortly after intake of glucose-rich food, SGLT1 abundance in the luminal membrane of the small intestine is increased. This upregulation occurs via glucose-induced acceleration of the release of SGLT1-containing vesicles from the trans-Golgi network (TGN), which is regulated by a domain of protein RS1 (RSC1A1) named RS1-Reg.

Role of Human Organic Cation Transporter 1 (hOCT1) Polymorphisms in Lamivudine (3TC) Uptake and Drug-Drug Interactions.

Lamivudine (3TC), a drug used in the treatment of HIV infection, needs to cross the plasma membrane to exert its therapeutic action. Human Organic cation transporter 1 (hOCT1), encoded by the SLC22A1 gene, is the transporter responsible for its uptake into target cells. As SLC22A1 is a highly polymorphic gene, the aim of this study was to determine how SNPs in the OCT1-encoding gene affected 3TC internalization and its interaction with other co-administered drugs.

Phosphorylation of RS1 (RSC1A1) Steers Inhibition of Different Exocytotic Pathways for Glucose Transporter SGLT1 and Nucleoside Transporter CNT1, and an RS1-Derived Peptide Inhibits Glucose Absorption.

Cellular uptake adapts rapidly to physiologic demands by changing transporter abundance in the plasma membrane. The human gene RSC1A1 codes for a 67-kDa protein named RS1 that has been shown to induce downregulation of the sodium-D-glucose cotransporter 1 (SGLT1) and of the concentrative nucleoside transporter 1 (CNT1) in the plasma membrane by blocking exocytosis at the Golgi. Injecting RS1 fragments into Xenopus laevis oocytes expressing SGLT1 or CNT1 and measuring the expressed uptake of α-methylglucoside or uridine 1 hour later, we identified a RS1 domain (RS1-Reg) containing multiple predicted phosphorylation sites that is responsible for this post-translational downregulation of SGLT1 and CNT1.

The impact of high-fat diet on metabolism and immune defense in small intestine mucosa.

Improved procedures for sample preparation and proteomic data analysis allowed us to identify 7700 different proteins in mouse small intestinal mucosa and calculate the concentrations of >5000 proteins. We compared protein concentrations of small intestinal mucosa from mice that were fed for two months with normal diet (ND) containing 34.4% carbohydrates, 19.

Substrate- and cell contact-dependent inhibitor affinity of human organic cation transporter 2: studies with two classical organic cation substrates and the novel substrate cd2+.

Polyspecific organic cation transporter Oct2 from rat (gene Slc22A2) has been previously shown to transport Cs(+). Here we report that human OCT2 (hOCT2) is able to transport Cd(2+) showing substrate saturation with a Michaelis-Menten constant (Km) of 54 ± 5.8 μM.

A substrate binding hinge domain is critical for transport-related structural changes of organic cation transporter 1.

Organic cation transporters are membrane potential-dependent facilitative diffusion systems. Functional studies, extensive mutagenesis, and homology modeling indicate the following mechanism. A transporter conformation with a large outward-open cleft binds extracellular substrate, passes a state in which the substrate is occluded, turns to a conformation with an inward-open cleft, releases substrate, and subsequently turns back to the outward-open state.

The large extracellular loop of organic cation transporter 1 influences substrate affinity and is pivotal for oligomerization.

Polyspecific organic anion transporters (OATs) and organic cation transporters (OCTs) of the SLC22 transporter family play a pivotal role in absorption, distribution, and excretion of drugs. Polymorphisms in these transporters influence therapeutic effects. On the basis of functional characterizations, homology modeling, and mutagenesis, hypotheses for how OCTs bind and translocate structurally different cations were raised, assuming functionally competent monomers.

Cell free expression and functional reconstitution of eukaryotic drug transporters.

Polyspecific organic cation and anion transporters of the SLC22 protein family are critically involved in absorption and excretion of drugs. To elucidate transport mechanisms, functional and biophysical characterization of purified transporters is required and tertiary structures must be determined. Here, we synthesized rat organic cation transporters OCT1 and OCT2 and rat organic anion transporter OAT1 in a cell free system in the absence of detergent.

Identification of cysteines in rat organic cation transporters rOCT1 (C322, C451) and rOCT2 (C451) critical for transport activity and substrate affinity.

Effects of the sulfhydryl reagent methylmethanethiosulfonate (MMTS) on functions of organic cation transporters (OCTs) were investigated. Currents induced by 10 mM choline [I(max(choline))] in Xenopus laevis oocytes expressing rat OCT1 (rOCT1) were increased four- to ninefold after 30-s incubation with 5 mM MMTS whereas I(max(choline)) by rat OCT2 was 70% decreased. MMTS activated the rOCT1 transporter within the plasma membrane without changing stoichiometry between translocated charge and cation.

RS1 (RSC1A1) regulates the exocytotic pathway of Na+-D-glucose cotransporter SGLT1.

The product of gene RSC1A1, named RS1, participates in transcriptional and posttranscriptional regulation of the sodium-d-glucose cotransporter SGLT1. Using coexpression in oocytes of Xenopus laevis, posttranscriptional inhibition of human SGLT1 (hSGLT1) and some other transporters by human RS1 (hRS1) was demonstrated previously. In the present study, histidine-tagged hRS1 was expressed in oocytes or Sf9 cells and purified using nickel(II)-charged nitrilotriacetic acid-agarose.

Purification and functional reconstitution of the rat organic cation transporter OCT1.

The rat organic cation transporter rOCT1 with six histidine residues added to the C-terminus was expressed in Sf9 insect cells, and expression of organic cation transport was demonstrated. To purify rOCT1 protein, Sf9 cells were lysed with 1% (w/v) CHAPS [3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate], centrifuged, and subjected to sequential affinity chromatography using lentil-lectin Sepharose and nickel(II)-charged nitrilotriacetic acid-agarose. This procedure yielded approximately 70 microg of purified rOCT1 protein from 10 standard culture plates.

A secreted metallo protease from Aeromonas hydrophila exhibits prothrombin activator activity.

Detection, purification, and partial characterization of a protease from Aeromonas hydrophila capable of cleaving prothrombin into active thrombin is described. The protease has been characterized with respect to enzymatic characteristics such as optimum reaction conditions for prothrombin activation, usage of additional substrates, as well as sensitivity against inhibitors. The protease activity can reversibly be inhibited by Me2+ chelating agents like ethylenediamine tetraacetic acid.

Identification of manganese superoxide dismutase as a NO-regulated gene in rat glomerular mesangial cells by 2D gel electrophoresis.

The course of inflammatory glomerular diseases is accompanied by changes in the expression of matrix-associated proteins, growth factors, and mediators in renal mesangial cells. Furthermore, the production of nitric oxide (NO) by the inducible isoform of nitric oxide synthase (iNOS) is enhanced after stimulation with pro-inflammatory cytokines. NO has been demonstrated to be a potent modulator of gene expression.