Biomedical subjects

R Lanz

Publications and source records attributed to R Lanz.

At least 19 recordsLinked to original sources

PubMed2003

Efficacy and safety of ketotifen eye drops in the treatment of seasonal allergic conjunctivitis.

BACKGROUND: Ketotifen blocks histamine H(1) receptors, stabilises mast cells, and prevents eosinophil accumulation. These multiple, pharmacological mechanisms provided the rationale for assessing the efficacy and safety of ketotifen 0.025% eye drops in subjects with seasonal allergic conjunctivitis (SAC) in an environmental setting. METHODS: This was a double masked, randomised, multicentre trial conducted in Australia. Subjects were randomly assigned to ketotifen fumarate 0.025% ophthalmic solution, placebo (as vehicle), or levocabastine hydrochloride 0.05% ophthalmic suspension, twice daily in each eye for a 4 week period. Subjects were assessed at follow up (days 5-8) and termination (days 25-31) visits. The primary efficacy variable was the responder rate, based on the subjects' assessment of global efficacy at the follow up visit. RESULTS: 519 subjects were randomised to treatment. At the follow up visit, the responder rate, based on subjects' assessment of global efficacy, was significantly greater in the ketotifen group (49.5%) than in the placebo group (33.0%) for subjects with a positive diagnostic test for pollen allergy (p = 0.02). The investigators' assessment of responder rates also showed that ketotifen was superior to placebo (p = 0.001). Ketotifen produced a significantly better outcome than levocabastine (p<0.05) for relief of signs and symptoms of SAC, at both the follow up and the termination visit. The type and frequency of adverse events were similar across treatment groups. CONCLUSIONS: In an environmental setting, ketotifen fumarate 0.025% ophthalmic solution was well tolerated and effective in reducing the signs and symptoms of SAC, and in preventing their recurrence. Ketotifen consistently showed the best efficacy in comparison with both placebo and levocabastine. These results indicate that ketotifen eye drops are a valuable treatment option for this condition.

Anti-Allergic Agents↗

PubMed2000

RAC-3 is a NF-kappa B coactivator.

It has been shown that the molecular mechanism by which cytokines and glucocorticoids mutually antagonize their functions involves a mutual glucocorticoid receptor (GR)/nuclear factor-kappa B (NF-kappa B) transrepression. Here we report a role for the nuclear receptor coactivator RAC3, in modulating NF-kappa B transactivation. We found that RAC3 functions as a coactivator by binding to the active form of NF-kappa B and that overexpression of RAC3 restores GR-dependent transcription neglecting GR/NF-kappa B transrepression. The competition between GR and NF-kappa B for binding to RAC3 may represent a general mechanism by which both transcription factors mutually antagonize their activity.

Binding, Competitive↗

PubMed1999

Mechanism of phosphoryl transfer in the dimeric IIABMan subunit of the Escherichia coli mannose transporter.

The mannose transporter of bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) mediates uptake of mannose, glucose, and related hexoses by a mechanism that couples translocation with phosphorylation of the substrate. It consists of the transmembrane IICMan.IIDMan complex and the cytoplasmic IIABMan subunit. IIABMan has two domains (IIA and IIB) that are linked by a 60-A long alanine-proline-rich linker. IIABMan transfers phosphoryl groups from the phospho-histidine-containing phospho-carrier protein of the PTS to His-10 on IIA, hence to His-175 on IIB, and finally to the 6'-OH of the transported hexose. IIABMan occurs as a stable homodimer. The subunit contact is mediated by a swap of beta-strands and an extensive contact area between the IIA domains. The H10C and H175C single and the H10C/H175C double mutants were used to characterize the phosphoryl transfer between IIA to IIB. Subunits do not exchange between dimers under physiological conditions, but slow phosphoryl transfer can take place between subunits from different dimers. Heterodimers of different subunits were produced in vitro by GuHCl-induced unfolding and refolding of mixtures of two different homodimers. With respect to wild-type homodimers, the heterodimers have the following activities: wild-type.H10C, 50%; wild-type.H175C 45%; H10C.H175C, 37%; and wild-type.H10C/H175C (double mutant), 29%. Taken together, this indicates that both cis and trans pathways contribute to the maximal phosphotransferase activity of IIABMan. A phosphoryl group on a IIA domain can be transferred either to the IIB domain on the same or on the second subunit in the dimer, and interruption of one of the two pathways results in a reduction of the activity to 70-80% of the control.

Bacterial Proteins↗

PubMed1999

Effects of tryptophan to phenylalanine substitutions on the structure, stability, and enzyme activity of the IIAB(Man) subunit of the mannose transporter of Escherichia coli.

The hydrophilic subunit of the mannose transporter (IIAB(Man)) of Escherichia coli is a homodimer that contains four tryptophans per monomer, three in the N-terminal domain (Trp12, Trp33, and Trp69) and one in the C-terminal domain (Trp182). Single and double Trp-Phe mutants of IIABMan and of the IIA domain were produced. Fluorescence emission studies revealed that Trp33 and Trp12 are the major fluorescence emitters, Trp69 is strongly quenched in the native protein and Trp182 strongly blue shifted, indicative of a hydrophobic environment. Stabilities of the Trp mutants of dimeric IIA(Man) and IIAB(Man) were estimated from midpoints of the GdmHCl-induced unfolding transitions and from the amount of dimers that resisted dissociation by SDS (sodium dodecyl sulfate), respectively. W12F exhibited increased stability, but only 6% of the wild-type phosphotransferase activity, whereas W33F was marginally and W69F significantly destabilized, but fully active. Second site mutations W33F and W69F in the background of the W12F mutation reduced protein stability and suppressed the functional defect of W12F. These results suggest that flexibility is required for the adjustments of protein-protein contacts necessary for the phosphoryltransfer between the phosphorylcarrier protein HPr, IIA(Man), IIB(Man), and the incoming mannose bound to the transmembrane IIC(Man)-IID(Man) complex.

Amino Acid Substitution↗

PubMed1998

Neurite fasciculation mediated by complexes of axonin-1 and Ng cell adhesion molecule.

Neural cell adhesion molecules composed of immunoglobulin and fibronectin type III-like domains have been implicated in cell adhesion, neurite outgrowth, and fasciculation. Axonin-1 and Ng cell adhesion molecule (NgCAM), two molecules with predominantly axonal expression exhibit homophilic interactions across the extracellular space (axonin- 1/axonin-1 and NgCAM/NgCAM) and a heterophilic interaction (axonin-1-NgCAM) that occurs exclusively in the plane of the same membrane (cis-interaction). Using domain deletion mutants we localized the NgCAM homophilic binding in the Ig domains 1-4 whereas heterophilic binding to axonin-1 was localized in the Ig domains 2-4 and the third FnIII domain. The NgCAM-NgCAM interaction could be established simultaneously with the axonin-1-NgCAM interaction. In contrast, the axonin-1-NgCAM interaction excluded axonin-1/axonin-1 binding. These results and the examination of the coclustering of axonin-1 and NgCAM at cell contacts, suggest that intercellular contact is mediated by a symmetric axonin-12/NgCAM2 tetramer, in which homophilic NgCAM binding across the extracellular space occurs simultaneously with a cis-heterophilic interaction of axonin-1 and NgCAM. The enhanced neurite fasciculation after overexpression of NgCAM by adenoviral vectors indicates that NgCAM is the limiting component for the formation of the axonin-12/NgCAM2 complexes and, thus, neurite fasciculation in DRG neurons.

Animals↗

PubMed1998

Mutational analysis of invariant arginines in the IIAB(Man) subunit of the Escherichia coli phosphotransferase system.

The mannose transporter of bacterial phosphotransferase system mediates uptake of mannose, glucose, and related hexoses by a mechanism that couples translocation with phosphorylation of the substrate. It consists of the transmembrane IIC(Man)-IID(Man) complex and the cytoplasmic IIAB(Man) subunit. IIAB(Man) has two flexibly linked domains, IIA(Man) and IIB(Man), each containing a phosphorylation site (His-10 and His-175). Phosphoryl groups are transferred from the phosphoryl carrier protein phospho-HPr to His-10, hence to His-175 and finally to the 6' OH of the transported hexose. Phosphate-binding sites and phosphate-catalytic sites frequently contain arginines, which by their guanidino group can stabilize phosphate through hydrogen bonding and electrostatic interactions. IIB(Man) contains five arginines which are invariant in the homologous IIB subunits of Escherichia coli, Klebsiella pneumoniae and Bacillus subtilis. The IIA domains have no conserved arginines. The five arginines were replaced by Lys or Gln one at a time, and the mutants were analyzed for transport and phosphorylation activity. All five IIB mutants can still be phosphorylated at His-175 by the IIA domain. R172Q is completely inactive with respect to glucose phosphotransferase (phosphoryltransfer from His-175 to the 6' OH of Glc) and hexose transport activity. R168Q has no hexose transport and strongly reduced phosphotransferase activity. R204K has no transport but almost normal phosphotransferase activity. R304Q has only slightly reduced transport activity. R190K behaves like wild-type IIAB(Man). Arg-168, Arg-172, and Arg-304 are part of the hydrogen bonding network on the surface of IIB, which contains the active site His-175 and the interface with the IIA domain (Schauder, S., Nunn, R.S., Lanz, R., Erni, B. and Schirmer, T. (1998) J. Mol. Biol. 276, 591-602) (Protein Data Bank accession code 1BLE). Arg-204 is at the putative interface between IIB(Man) and the IIC(Man)-IID(Man) complex.

Arginine↗

PubMed1998

The glucose transporter of the Escherichia coli phosphotransferase system. Mutant analysis of the invariant arginines, histidines, and domain linker.

The glucose transporter of the bacterial phosphotransferase system (PTS) consists of a hydrophilic (IIAGlc) and a transmembrane subunit (IICBGlc). IICBGlc has two domains (C and B), which are linked by a highly invariant sequence. Transport of glucose by IIC and phosphorylation by IIB are tightly coupled processes. Three motifs that are strongly conserved in 12 homologous PTS transporters, namely two invariant arginines (Arg-424 and Arg-426) adjacent to the phosphorylation site (Cys-421), the invariant interdomain sequence KTPGRED, and two conserved histidines (His-211 and His-212) in the IIC domain were mutated and the mutant proteins characterized in vivo and in vitro for transport and phosphorylation activity. Replacement of the strongly beta-turn favoring residues Thr and Gly of the linker by alpha-helix favoring Ala results in strong reduction of activity, whereas the substitutions of the other residues have only minor effects. The R424K and R426K mutants can be phosphorylated by IIAGlc but can no longer donate the phosphoryl group to glucose. The H211Q and H212Q mutants continue to phosphorylate glucose at a reduced rate but H212Q can no longer transport glucose. Mixtures of purified R424K/H212Q and R426K/H212Q have 10% of wild-type phosphorylation activity and when coexpressed in Escherichia coli support glucose transport.

Alanine↗

PubMed1998

Determination of dimethindene in human tears by high-performance liquid chromatography.

A high-performance liquid chromatographic method is described for the determination of dimethindene in human tears. The tear samples were diluted in a 0.01 M hydrochloric acid-n-propanol mixture to prevent the irreversible adsorption of dimethindene. The diluted samples were directly injected into the chromatographic system to avoid sample pretreatment. The validation data demonstrate that the method is specific, precise and accurate within the calibration range of 12 to 1000 ng/ml dimethindene free base.

Anti-Allergic Agents↗

PubMed1998

Crystal structure of the IIB subunit of a fructose permease (IIBLev) from Bacillus subtilis.

The bacterial phosphoenolpyruvate-dependent phosphotransferase system (PTS) mediates both the uptake of carbohydrates across the cytoplasmic membrane and their phosphorylation. During this process, a phosphoryl group is transferred from phosphoenolpyruvate via the general PTS proteins enzyme I, HPr and the sugar-specific components IIA, IIB to the transported sugar. The crystal structure of the IIB subunit of a fructose transporter from Bacillus subtilis (IIBLev) was solved by MIRAS to a resolution of 2.9 A. IIBLev comprises 163 amino acid residues that are folded into an open, mainly parallel beta-sheet with helices packed on either face. The phosphorylation site (His15) is located on the first loop (1/A) at one of the topological switch-points of the fold. Despite different global folds, IIBLev and HPr have very similar active-site loop conformations with the active-site histidine residues located close to the N terminus of the first helix. This resemblance may be of functional importance, since both proteins exchange a phosphoryl group with the same IIA subunit. The structural basis of phosphoryl transfer from HPr to IIAMan to IIBMan was investigated by modeling of the respective transition state complexes using the known HPr and IIAMan structures and a homology model of IIBMan that was derived from the IIBLev structure. All three proteins contain a helix that appears to be suitable for stabilization of the phospho-histidine by dipole and H-bonding interactions. Smooth phosphoryl transfer from one N-cap position to the other appears feasible with a minimized transition state energy due to simultaneous interactions with the donor and the acceptor helix.

Amino Acid Sequence↗

PubMed1997

Glucose transporter of Escherichia coli: NMR characterization of the phosphocysteine form of the IIB(Glc) domain and its binding interface with the IIA(Glc) subunit.

The transmembrane subunit of the glucose transporter, IICB(Glc), mediates vectorial transport with concomitant phosphorylation of glucose. Glucose phosphorylation proceeds through a cystein phosphate intermediate of the cytosolic IIB domain of IIC(Glc), which is phosphorylated by the IIA(Glc) subunit of the glucose transporter. Two- and three-dimensional NMR experiments were used to characterize the phosphorylation of the 10 kDa subclonal IIB domain and the complementary binding interfaces of [15N]IIB and [15N]IIA(Glc). The largest chemical shift perturbations and the only NOE differences accompanying IIB phosphorylation are confined to the active site residue Cys35, as well as Ile36, Thr37, Arg38, Leu39, and Arg40, which are all located in the turn between strands beta1 and beta2 and on beta2 itself. The significant increase of the amide cross-peak intensities of Ile36, Thr37, and Arg38 upon phosphorylation suggests that the conformational freedom of these groups becomes restrained, possibly due to hydrogen bonding to the oxygens of the bound phosphate and to interactions between the guanidinium group of Arg38 and the phosphoryl group. The residues of IIB which experience chemical shift perturbations upon binding of IIA are located on a protruding surface formed by residues of strands beta1, beta2, and beta4, the beta4/alpha3 loop, and residues from the first two turns of alpha3. The corresponding binding surface of the IIA(Glc) domain is comprised of residues on five adjacent beta-strands and two short helices surrounding the active site His90. The binding surface of IIA(Glc) for IIB coincides with the binding surface for HPr, the phosphoryl carrier protein by which IIA(Glc) is phosphorylated [Chen, Y., Reizer, J., Saier, M. H., Fairbrother, W. J., & Wright, P. E. (1993) Biochemistry 32, 32-37].

Binding Sites↗

PubMed1997

Secondary structure of the IIB domain of the Escherichia coli mannose transporter, a new fold in the class of alpha/beta twisted open-sheet structures.

The mannose transporter of the Escherichia coli bacterial phosphotransferase system consists of three subunits: IIAB, IIC and IID. IIABMan transfers phosphoryl groups to the transported substrate via phosphohistidine intermediates. Its IIB domain was overexpressed and isotopically labelled with 13C, 15N and 2H. Heteronuclear 3D triple-resonance NMR experiments combined with a semi-automatic assignment procedure yielded the sequential assignment of the 1H, 13C and 15N backbone resonances. Based on the evaluation of conformationally sensitive parameters, the secondary structure of the IIBMan domain has been determined as an alpha/beta twisted open-sheet structure consisting of a six-stranded parallel beta-sheet with the novel strand order 3-2-4-1-5-6, six helices and a short two-stranded antiparallel beta-sheet.

Amino Acid Sequence↗

PubMed1997

The fructose transporter of Bacillus subtilis encoded by the lev operon: backbone assignment and secondary structure of the IIB(Lev) subunit.

The fructose transporter of the Bacillus subtilis phosphotransferase system consists of two membrane associated (IIA and IIB) and two transmembrane (IIC and IID) subunits [Martin-Verstraete, I., Débarbouille, M., Klier, A. & Rapoport, G. (1990) J. Mol. Biol. 214, 657-671] . It mediates uptake by a mechanism which couples translocation to phosphorylation of the transported solute. The 18-kDa IIBLev subunit transfers phosphoryl groups from His9 of the IIA subunit to the sugar. The three-dimensional structure of IIBLev or similar proteins is not known. IIBLev was overexpressed in Escherichia coli and isotopically labelled with 13C/15N in H2O as well as in 70% D2O. 15N-edited NOESY, 13C-edited NOESY and 13C,15N triple-resonance experiments yielded a nearly complete assignment of the 1H, 13C and 15N resonances. Based on qualitative interpretation of NOE, scalar couplings, chemical shift values and amide exchange data, the secondary structure and topology of IIBLev was determined. IIBLev comprises six parallel beta-strands, one antiparallel beta-strand and 5 alpha-helices. The order of the major secondary-structure elements is (beta alpha)5beta (strand order 7651423). Assuming that the (beta alpha beta)-motives form right-handed turn structures, helices alphaA and alphaB are packed to one face and helices alphaC, alphaD and alphaE to the opposite face of the parallel beta-sheet. His15 which is transiently phosphorylated during catalysis is located in the loop beta1/alphaA of the topological switch point. The amino terminal (beta/alpha)4 part of IIBLev has the same topology as phosphoglyceromutase (PGM; PDB entry 3pgm). Both proteins catalyze phosphoryltransfer reactions which proceed through phosphohistidine intermediates and they show a similar distribution of invariant residues in the topologically equivalent positions of their active sites. The protein fold of IIBLev has no similarity to any of the known structures of other phosphoenolpyruvate-dependent-carbohydrate-phosphotransferase-system proteins.

Amino Acid Sequence↗

PubMed1995

[Ecology and postmodernity. An ethical point of view].

This essay deals with critique of the "Modern Reason". Also, it aims to promote the debate about ethical and political issues of our technological/eco-depredating and environmentally unsound model of development. We argue about ecology like a new knowledge point of view, from which to define criteria for the reformulation of the environment/society relationship, in a postmodern context.

Conservation of Natural Resources↗

PubMed1990

[Covering physician system in the regional hospital].

1. At first the socio-political context is shown. Equality and inflation of demands have their price in the modern society of prosperity. Health, however, has become number one in our demands. 2. Nearly half of all the 700 surgeons of Switzerland are working in public hospitals. A few more than the other half are in private practice. Stationary surgery is done either in a public hospital or in a private clinic, the last one being either subsidized or not. 3. All the hospitals for surgical formation and the places with private hospitals are mentioned. 4. "Belegärzte" treat their patients in their private practice and operate on them, when they become stationary, in all the three types of hospitals cited above. 5. An analysis of the status quo is thought to prepare the questions for the following round table discussion, which might show us new ways in between tradition on one hand and alteration and futurism on the other hand.

Hospital Departments↗

PubMed1986

Antipyretic analgesics inhibit prostaglandin release from astrocytes and macrophages similarly.

The effect of acid and non-acid antipyretic analgesics on prostaglandin (PG) release from cultured mouse astrocytes and peritoneal macrophages was investigated in order to test the hypothesis that the non-acid compounds are more potent inhibitors of PG formation in brain than in peripheral tissues. Stimulation of the cells by the divalent cation ionophore A 23187 (10(-6) mol/l) induced PG release from astrocytes and macrophages (mainly PGD2 and PGE2, respectively). This PG release was inhibited by acetylsalicylic acid (10(-5) - 10(-6) mol/l) and indomethacin (10(-6) - 10(-9) mol/l) but also by high concentrations (10(-3) - 10(-5) mol/l) of the non-acid compounds 4-methyl-aminophenazone, the main active metabolite of dipyrone (metamizol), and acetaminophen (paracetamol). No difference was found in the inhibitory potency of the drugs in astrocytes and macrophages, suggesting that a specific sensitivity of brain cells toward non-acid antipyretic analgesics does not contribute to their analgesic effect.

Animals↗

PubMed1986

Release of cytoprotective PGE2 from cultured macrophages induced by antacids and sucralfate.

Aluminium-containing antacids and sucralfate possess cytoprotective effects supposedly due to the release of endogenous prostaglandins. In the present study possible mechanisms of prostaglandin production by aluminium-containing and related compounds were investigated in cultured macrophages. We found no indication that mechanical action, particle size or hyperosmolality (up to certain limits) play a major role in initiating enhanced prostaglandin production. Instead, it is likely that specific physicochemical properties as surface charge and the corresponding octahedral crystalline structure of Al(OH)3 are major factors mediating the necessary membrane interactions leading to prostaglandin release.

Aluminum↗

PubMed1986

Tissue culture methods for the investigation of anti-inflammatory drugs.

Tissue culture methods are used increasingly in the investigation of anti-inflammatory drugs. Compared to in vivo experiments they offer the advantages of a) relative reproducibility, b) reduced cost, and c) simplified interpretation of results. Moreover, tissue culture methods can be applied without major ethical concern. The disadvantage of cell culture techniques is the need to re-check in vivo the medical relevance of all data obtained. A few applications of cell culture methods are exemplified by results obtained in our laboratory from experiments using macrophages, endothelial cells and chondrocytes.

Anti-Inflammatory Agents↗

PubMed1986

The effects of acidic and nonacidic pyrazoles on arachidonic acid metabolism in mouse peritoneal macrophages.

The effects of acidic and nonacidic pyrazole derivatives and their metabolites on arachidonic acid metabolism have been investigated in mouse peritoneal macrophages stimulated with the calcium ionophore A 23 187 (10(-6) Mol/l). In the group of the acidic compounds with anti-inflammatory properties, phenylbutazone and butyl malonic acid mono (1-phenylhydrazide), the hydrolysis product of mofebutazone, inhibited prostaglandin production in a dose-dependent manner (10(-4)-10(-6) Mol/l). In contrast, mofebutazone itself and its hydroxylation product, 4-OH-mofebutazone, failed to show any activity. Similarly, in the case of bumadizone, an anti-inflammatory drug structurally related to phenylbutazone, no inhibitory effect on prostaglandin release was found either. The nonacidic pyrazole derivatives with antipyretic and anti-inflammatory activity, antipyrine, isopropylaminophenazone, as well as metamizol and its active metabolites 4-methylaminophenazone and 4-aminophenazone, also inhibited prostaglandin release dose-dependently. This was found to be paralleled by an increased leukotriene C4 production. Neither of the main excretory metabolites of metamizol, acetyl- and formylaminophenazone, showed any effect. The concentration levels at which the nonacidic compounds affected arachidonic acid metabolism (approx. 10(-4) Mol/l) were high enough to elicit anti-inflammatory effects. They were far higher, though, than the plasma levels producing antipyretic and analgesic effects that are reached after therapeutic doses.

Aminopyrine↗