Position Of Label Research Articles

Private label positioning: Quality versus feature differentiation from the national brand

This paper investigates the retailer's problem of positioning her private label against two national brands in terms of both product quality and product features. Using a demand function derived from consumer utility, we show that the private label's best positioning strategy depends on the nature of the national brands’ competition and its own quality. When the national brands are differentiated, a high quality private label should position closer to a stronger national brand, and a low quality private label should position closer to a weaker national brand. When the national brands are undifferentiated, the private label should differentiate from both national brands.

Reaction of 5−40 eV Ions with Self-Assembled Monolayers

The reaction of 5-40 eV O(+) and Ne(+) ions with alkanethiolate and semifluorinated alkanethiolate self-assembled monolayers (SAMs) is studied under ultrahigh vacuum (UHV) conditions. Whereas Ne(+) simply sputters fragments from the surface, O(+) can also abstract surface atoms and break C-C bonds in both the hydrocarbon and fluorocarbon SAM chains. Isotopic labeling experiments reveal that O(+) initially abstracts hydrogen atoms from the outermost two carbon atoms on an alkanethiolate SAM chain. However, the position of the isotopic label quickly becomes scrambled along the chain as the SAM is damaged through continuous ion bombardment. Scanning tunneling microscopy (STM) monitors changes in the SAM conformational structure at various stages during 5 eV ion bombardment. STM images indicate that O(+) reacts less efficiently with dodecanethiolate molecules packed internally within a structural domain than it does with molecules adsorbed at domain boundaries or near defect sites. STM images recorded after Ne(+) bombardment suggest that Ne(+) attacks the SAM exclusively near the domain boundaries. Taken collectively, these experiments advance our understanding of the degradation pathways suffered by polymeric satellite materials in the low-earth orbit (LEO) space environment.

Position of the fluorescent label is a crucial factor determining signal intensity in microarray hybridizations

A key issue in applications of short oligonucleotide-based microarrays is how to design specific probes with high sensitivity. Some details of the factors affecting microarray hybridization remain unclear, hampering a reliable quantification of target nucleic acids. We have evaluated the effect of the position of the fluorescent label [position of label (POL)] relative to the probe-target duplex on the signal output of oligonucleotide microarrays. End-labelled single-stranded DNA targets of different lengths were used for hybridization with perfect-match oligonucleotide probe sets targeting different positions of the same molecule. Hybridization results illustrated that probes targeting the labelled terminus of the target showed significantly higher signals than probes targeting other regions. This effect was independent of the target gene, the fluorophore and the slide surface chemistry. Comparison of microarray signal patterns of fluorescently end-labelled, fluorescently internally random-labelled and radioactively end-labelled target-DNAs with the same set of oligonucleotide probes identified POL as a critical factor affecting signal intensity rather than binding efficiency. Our observations define a novel determinant for large differences of signal intensities. Application of the POL effect may contribute to better probe design and data interpretation in microarray applications.

Synthesis of Aliphatic [carbonyl‐11C]Esters Using [11C]Carbon Monoxide

AbstractAliphatic esters were labelled with a short‐lived radionuclide, 11C with t½ = 20.3 min, at the carbonyl position using [11C]carbon monoxide via rapid (6 min) photoinduced radical‐mediated carbonylation reactions. The esters were prepared from primary, secondary, and tertiary alkyl iodides, and various alcohols, including tert‐butyl alcohol and phenol. The use of strong bases was necessary to achieve good radiochemical yields in short reaction times. Isolated decay‐corrected radiochemical yields were in the range of 40–68 %. For example, methyl hydrogen dodecanoate was labelled at the ester carbonyl in 61 % isolated decay‐corrected radiochemical yield with a specific radioactivity of 158 GBq/μmol within approximately 25 min of the production of [11C]carbon monoxide. Two (13C)substituted esters were synthesised using this method to verify the labelling position. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Palladium‐Mediated 11C‐Carbonylative Cross‐Coupling of Alkyl/Aryl Iodides with Organostannanes: An Efficient Synthesis of Unsymmetrical Alkyl/Aryl [11C‐carbonyl]Ketones

Abstract[11C]Carbon monoxide in low concentration, palladium complexes, alkyl/aryl iodides, and organostannanes are utilized in the synthesis of twenty alkyl [carbonyl‐11C]ketones. The activated palladium(0) species [Pd{P(o‐Tol)3}2] was generated in situ from tris(dibenzylideneacetone)palladium(0) [Pd2(dba)3] and a large excess of tri‐o‐tolylphosphane [P(o‐Tol)3]. The Stille coupling reactions were performed in a micro‐autoclave system. Radiochemical yields of 11C‐labelled alkyl/aryl ketones were in the range of 37–98 % with specific radioactivity up to 300 GBq μmol–1. Using this method, 4'‐aminoacetophen[13C‐arbonyl)one 6 was synthesised in order to confirm the position of labelling (δ = 196.7 ppm, CDCl3). The presented approach is an efficient way for synthesising 11C‐labelled alkyl/aryl ketones with acceptable radiochemical yield and is generally applicable in 13C‐labelling syntheses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

N,1-15N2]-2‘-Deoxyadenosines

[reaction: see text] An efficient route to deoxyadenosine derivatives labeled on both the amino group and nitrogen 1 is uncovered. First, 3',5'-di-O-acetyl-2'-deoxy-1-(2-nitrobenzenesulfonyl)inosine (2a) and only 1.1 equiv of (15)NH4Cl are used for labeling position 1 (1a) through the isolation of the open intermediate and its cyclization with DBU in anhydrous CH3CN. Inosine 1a is then converted to [N,1-(15)N2]-3',5'-di-O-acetyl-N6-benzoyl-2'-deoxyadenosine (5a, the precursor of 6a) via a Pd/dppf-catalyzed chloride-to-benzamide replacement, by using again only 1.1 equiv of the labeling source.

Localization of the N-terminal Domain in Light-harvesting Chlorophyll a/b Protein by EPR Measurements

The conformational distribution of the N-terminal domain of the major light-harvesting chlorophyll a/b protein (LHCIIb) has been characterized by electron-electron double resonance yielding distances between spin labels placed in various domains of the protein. Distance distributions involving residue 3 near the N terminus turned out to be bimodal, revealing that this domain, which is involved in regulatory functions such as balancing the energy flow through photosystems (PS) I and II, exists in at least two conformational states. Models of the conformational sub-ensembles were generated on the basis of experimental distance restraints from measurements on LHCIIb monomers and then checked for consistency with the experimental distance distribution between residues 3 in trimers. Only models where residue 3 is located above the core of the protein and extends into the aqueous phase on the stromal side fit the trimer data. In the other state, which consequently is populated only in monomers, the N-terminal domain extends sideways from the protein core. The two conformational states may correspond to two functional states of LHCIIb, namely trimeric LHCIIb associated with PSII in stacked thylakoid membranes and presumably monomeric LHCIIb associated with PSI in nonstacked thylakoids. The switch between these two is known to be triggered by phosphorylation of Thr-6. A similar phosphorylation-induced conformational change of the N-terminal domain has been observed by others in bovine annexin IV which, due to the conformational switch, also loses its membrane-aggregating property.

Structural Uncoupling between Opposing Domains of Oxidized Calmodulin Underlies the Enhanced Binding Affinity and Inhibition of the Plasma Membrane Ca-ATPase

Stabilization of the plasma membrane Ca-ATPase (PMCA) in an inactive conformation upon oxidation of multiple methionines in the calcium regulatory protein calmodulin (CaM) is part of an adaptive cellular response to minimize ATP utilization and the generation of reactive oxygen species (ROS) under conditions of oxidative stress. To differentiate oxidant-induced structural changes that selectively modify the amino-terminal domain of CaM from those that modulate the conformational coupling between the opposing domains, we have engineered a tetracysteine binding motif within helix A in the amino-terminal domain of calmodulin (CaM) that permits the selective and rigid attachment of the conformationally sensitive fluorescent probe 4',5'-bis(1,3,2-dithioarsolan-2-yl)fluorescein-(1,2-ethanedithiol)(2) (FlAsH-EDT(2)). The position of the FlAsH label in the amino-terminal domain provides a signal for monitoring its binding to the CaM-binding sequence of the PMCA. Following methionine oxidation, there is an enhanced binding affinity between the amino-terminal domain and the CaM-binding sequence of the PMCA. To identify oxidant-induced structural changes, we used frequency domain fluorescence anisotropy measurements to assess the structural coupling between helix A and the amino- and carboxyl-terminal domains of CaM. Helix A undergoes large amplitude motions in apo-CaM; following calcium activation, helix A is immobilized as part of a conformational switch that couples the opposing domains of CaM to stabilize the high-affinity binding cleft associated with target protein binding. Methionine oxidation disrupts the structural coupling between opposing globular domains of CaM, without affecting the calcium-dependent immobilization of helix A associated with activation of the amino-terminal domain to promote high-affinity binding to target proteins. We suggest that this selective disruption of the structural linkage between the opposing globular domains of CaM relieves steric constraints associated with high-affinity target binding, permitting the formation of new contact interactions between the amino-terminal domain and the CaM-binding sequence that stabilizes the PMCA in an inhibited conformation.

Phospholamban Pentamer Quaternary Conformation Determined by In-Gel Fluorescence Anisotropy,

We measured in-gel fluorescence anisotropy of phospholamban (PLB) labeled with the biarsenical fluorophore FlAsH at three different sites on the cytoplasmic domain. The 6 kDa monomer bands of FlAsH-tetracysPLB showed high anisotropy (r = 0.29), reflecting null homotransfer and low mobility (S = 0.85) on the nanosecond time scale of the FlAsH fluorescence lifetime. 30 kDa bands (pentameric PLB) within the same lanes exhibited low anisotropy, suggesting intrapentameric fluorescence energy homotransfer between PLB subunits. FlAsH labels positioned at residue -6, 5, or 23 showed a graduated pattern of fluorescence depolarization corresponding to resonance energy transfer radii of 46 +/-2, 38 +/- 4, and <25 A, respectively. Pentamer anisotropy increased with heating or fluorescence photobleaching toward a maximum value similar to that determined for monomeric PLB. Fluorescence resonance energy heterotransfer was also observed in vitro and in vivo within PLB pentamers colabeled with FlAsH and the biarsenical fluorophore ReAsH. In vitro heterotransfer efficiencies were graduated by labeling position, in harmony with homotransfer results. The calculated transfer radii compare favorably to distances predicted by a computer molecular model of the phospholamban pentamer constructed from NMR solution structures. The data support a helical pinwheel model for the PLB pentamer, in which the cytoplasmic domains bend sharply outward from the central bundle of helices.

Ab Initio Modeling of Amide I Coupling in Antiparallel β-Sheets and the Effect of 13C Isotopic Labeling on Infrared Spectra

Isotopic substitution with 13C on the amide C=O has become an important means of determining localized structural information about peptide conformations with vibrational spectroscopy. Various approaches to the modeling of the interactions between labeled amide sites, specifically for antiparallel two-stranded, beta-forming peptides, were investigated, including different force fields [dipole-dipole interaction vs density functional theory (DFT) treatments], basis sets, and sizes of model peptides used for ab initio calculations, as well as employing models of solvation. For these beta-sheet systems the effect of the relative positions of the 13C isotopic labels in each strand on their infrared spectra was investigated. The results suggest that the interaction between labeled amide groups in different strands can be used as an indicator of local beta-structure formation, because coupling between close-lying C=O groups on opposing chains leads to the largest frequency shifts, yet some alternate placements can lead to intensity enhancements. The basic character of the coupling interaction between labeled modes on opposing strands is independent of changes in peptide length, water solvent environment, twisting of the sheet structure, and basis set used in the calculations, although the absolute frequencies and detailed coupling magnitudes change under each of these perturbations. In particular, two strands of three amides each contain the basic interactions needed to simulate larger sheets, with the only exception that the C=O groups forming H-bonded rings at the termini can yield different coupling values than central ones of the same structure. Spectral frequencies and intensities were modeled ab initio by DFT primarily at the BPW91/6-31G** level for pairs of three, four, and six amide strands. Comparison to predictions of a classical coupled oscillator model show qualitative but not quantitative agreement with these DFT results.

Radical-Mediated Carboxylation of Alkyl Iodides with [11C]Carbon Monoxide in Solvent Mixtures

[reaction: see text] [carboxyl-(11)C]Carboxylic acids were prepared from alkyl iodides via photoinitiated radical reactions using 10(-)(8) mol of [(11)C]carbon monoxide in binary and ternary homogeneous solvent mixtures. Short- (isobutyric), medium-, and long-chain saturated fatty acids (heptadecanoic) were labeled with isolated decay-corrected radiochemical yields ranging from 55% to 70% in 5-7-min reactions. The conversion of [(11)C]carbon monoxide to products reached 80-90%. To obtain good yields in the reactions performed in water-acetonitrile and water-THF mixtures, the addition of tetrabutylammonium hydroxide or potassium hydroxide was essential. The carboxylation was efficient for primary and secondary alkyl iodides. The carboxylation of tertiary iodides was feasible for 1-iodoadamantane but not for tert-butyl iodide. The dependence of the radiochemical yields on reaction time, photoirradiation conditions, and organic and inorganic additives was studied. The method provides a one-step route to [carboxyl-(11)C]carboxylic acids; traditional methods, in contrast, would require several steps. For example, using the devised reaction conditions, 3.19 GBq of purified [1-(11)C]1,10-decanedicarboxylic acid (specific radioactivity 188 GBq/mumol) was obtained within 35 min of the end of 10 muAh bombardment. (1-(13)C)4-Phenylbutyric acid was synthesized using ((13)C)carbon monoxide for identifying the labeling position with (1)H and (13)C NMR.

Membrane-bound ARF1 peptide: interpretation of neutron diffraction data by molecular dynamics simulation methods

Adenosine diphosphate ribosylation factor-1 (ARF1) is activated by cell membrane binding of a self-folding N-terminal domain. We have previously presented four possible conformations of the membrane bound, human ARF1 N-terminal peptide in planar lipid bilayers of DOPC and DOPG (7:3 molar ratio), determined from lamellar neutron diffraction and circular dichroism data. In this paper we analyse the four possible conformations by molecular dynamics simulations. The aim of these simulations was to use MD to distinguish which of the four possible membrane bound structures was the most likely. The most likely conformation was determined according to the following criteria: (a) location of label positions on the peptide in relation to the bilayer, (b) lowest mean square displacement from the initial structure, (c) lowest system energy, (d) most peptide-lipid headgroup hydrogen bonding, (e) analysis of phi/psi angles of the peptide. These findings demonstrate the application of molecular dynamics simulations to explore neutron diffraction data.

Consumers' use of written product information

Two studies were conducted to investigate the predictive role of person-specific, product-specific, and situation-specific influences on the use of instruction manuals in the field of electrical consumer products. In a laboratory study, 42 participants were observed while putting a vacuum cleaner into operation. Situational primes (i.e., receiving a verbal cue that the packaging contains an instruction manual) increased the probability of the user manual being read. Additional verbal information that the manual contains information on energy-saving behaviours was especially motivating for persons with high environmental concern. Self-report data, collected on a wide range of products, suggest that product complexity is the best predictor of instruction manual use. In a second study with 30 participants, different positions of product labels were compared, i.e. placing the information on the packaging or directly onto the product. Information placed directly onto the product had a significantly higher influence on participants' actual behaviour than providing the same information on the packaging.

Infrared Dichroism of Isotope-edited α-Helices and β-Sheets

Isotope editing of amide infrared bands not only localises secondary structural elements within the protein but also yields conformational information that is not available from the linear dichroism of aligned samples without isotope editing. The additional information that can be derived on the orientational distribution of α-helices in membranes by the combined use of different amide bands and several positions of labelling is presented here. Also, the relationship between the azimuthal orientation of the transition moment and the protein structure is treated explicitly. A comprehensive analysis of the infrared dichroism for β-sheets and β-barrels is given here, for the first time. The orientation of the individual transition moments in a β-sheet that is essential for this analysis is derived for the different amide bands.

Empirical Relationships between Isotope-Edited IR Spectra and Helix Geometry in Model Peptides

Infrared spectroscopy (IR) is commonly used to study secondary structure of both peptides and proteins. The amide I band is very sensitive to peptide secondary structure, and the conformation of a peptide can be probed at the residue level by introducing site-specific isotope-labels into the peptide backbone. The replacement of a carbonyl (12)C with a (13)C results in a approximately 40 cm(-1) shift in the amide I' band. The amide I bands of specifically labeled helices should vary systematically as a function of the number and relative spacing of the labeled residues; thus one should be able to describe the conformation of a polypeptide in substantial detail by probing the changes in IR spectra as a function of the number and positioning of isotope labels. In this study, we report IR spectra of a series of differently labeled helical peptides. A series of 25mer peptides were synthesized based on the repeat sequence (AAAAK)(n). We have varied the number and spacing of the labels on each peptide and studied the changes in the (12)C and (13)C amide I' band due to label position. Our results indicate that changing the number of labels changes the frequency and intensity of both the (12)C and the (13)C amide mode. We also found that varying the spacing between labels causes these amide peaks to shift. Isotope labeling, combined with IR spectroscopy and theoretical predictions, may generate a description of peptide backbone conformations at the residue level.

Synthesis of 11C‐/13C‐Ketones by Suzuki Coupling

AbstractAryl triflates, methyl‐ or arylboronic acids, and a low concentration of [11C]carbon monoxide were employed on small scale in the syntheses of fifteen 11C‐labelled ketones using palladium‐mediated Suzuki coupling reactions. The reagents were confined in a micro‐autoclave and heated at 150 °C for 5 min. The reaction required the presence of LiBr, but no additional base. The 11C‐labelled products were obtained with decay‐corrected radiochemical yields in the range 10−70% and with high specific radioactivity (150−640 GBq/μmol). The radiochemical purity of the final products exceeded 98%. One 13C‐substituted ketone ([13C]‐2′‐benzonaphthone) was prepared and analysed by NMR spectroscopy for confirmation of the labelling position. The reference compound 2′‐benzonaphthone was prepared by a palladium‐catalysed reaction between sodium tetraphenylborate and 2‐naphthoyl chloride. 2‐Thienyl p‐tolyl ketone, 4‐nitrophenyl 2‐thienyl ketone and 2‐naphthyl 2‐thienyl ketone were prepared by reactions between thiophene‐2‐boronic acid and the corresponding acid chlorides. The presented approach is novel and seems to be an efficient method for the synthesis of a wide range of 11C‐ as well as 13C‐labelled ketones. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2004)

Conformational response of the phosphatidylcholine headgroup to bilayer surface charge: torsion angle constraints from dipolar and quadrupolar couplings in bicelles.

The effects of bilayer surface charge on the conformation of the phosphocholine group of phosphatidylcholine were investigated using a torsion angle analysis of quadrupolar and dipolar splittings in, respectively, (2)H and (13)C NMR spectra of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) labelled in the phosphocholine group with either deuterons (POPC-alpha-d(2), POPC-beta-d(2) and POPC-gamma-d(9)) or carbon-13 (POPC-alpha-(13)C and POPC-alphabeta-(13)C(2)) and incorporated into magnetically aligned bicelles containing various amounts of either the cationic amphiphile 1,2-dimyristoyl-3-trimethylammoniumpropane (DMTAP) or the anionic amphiphile 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG). Three sets of quadrupolar splittings, one from each of the three deuteron labelling positions, and three sets of dipolar splittings ((13)C(alpha)-(31)P, (13)C(alpha)-(13)C(beta), (13)C(beta)-(14)N), were measured at each surface charge, along with the (31)P residual chemical shift anisotropy. The torsion angle analysis assumed fast anisotropic rotation of POPC about its long molecular axis, thus projecting all NMR interactions onto that director axis of motion. Dipolar, quadrupolar and chemical shift anisotropies were calculated as a function of the phosphocholine internal torsion angles by first transforming into a common reference frame affixed to the phosphocholine group prior to motional averaging about the director axis. A comparison of experiment and calculation provided the two order parameters specifying the director orientation relative to the molecule, plus the torsion angles alpha(3), alpha(4) and alpha(5). Surface charge was found to have little effect on the torsion angle alpha(5) (rotations about C(alpha)-C(beta)), but to have large and inverse effects on torsion angles alpha(3) [rotations about P-O(11)] and alpha(4) [rotations about O(11)-C(alpha)], yielding a net upwards tilt of the P-N vector in the presence of cationic surface charge, and a downwards tilt in the presence of anionic surface charge, relative to neutrality.

A hopfield neural network algorithm for automatic name placement for point feature

This paper presents a method of adding label to the map especially for the point feature. This method overcomes the shortcoming of traditional methods, e.g. Conflict-Backtracking method. Its kernel algorithm use the hopfield neural network to find the best label position for point feature. The experimental results proves that this algorithm has good permanence and high speed.

Synthesis of [11C]/(13C)amines via carbonylation followed by reductive amination.

Twelve 11C-labelled amines were prepared via 11C-carbonylation followed by reductive amination. The 11C-carbonylation was performed in the presence of tetrakis(triphenylphosphine)palladium using aryl iodides or aryl triflates, [11C]carbon monoxide and phenyl-/methylboronic acid. The [11C]ketones formed in this step were then transformed directly into amines by reductive amination using different amines in the presence of TiCl4 and NaBH3CN. The 11C-labelled amines were obtained with decay-corrected radiochemical yields in the range 2-78%. The radiochemical purity of the isolated products exceeded 98%. (13C)Benzhydryl-phenyl-amine was synthesised and analysed by NMR spectroscopy for confirmation of the labelling position. Specific radioactivity was determined for the same compound. The reference compounds were prepared by reductive amination of ketones using conventional reaction conditions and three of the compounds were novel. The presented approach is a new method for the synthesis of [11C]/(13C)amines.

Visual registration for unprepared augmented reality environments

Despite the increasing sophistication of augmented reality (AR) tracking technology, tracking in unprepared environments still remains an enormous challenge according to a recent survey. Most current systems are based on a calculation of the optical flow between the current and previous frames to adjust the label position. Here we present two alternative algorithms based on geometrical image constraints. The first is based on epipolar geometry and provides a general description of the constraints on image flow between two static scenes. The second is based on the calculation of a homography relationship between the current frame and a stored representation of the scene. A homography can exactly describe the image motion when the scene is planar, or when the camera movement is a pure rotation, and provides a good approximation when these conditions are nearly met. We assess all three styles of algorithms with a number of criteria including robustness, speed and accuracy. We demonstrate two real-time AR systems here, which are based on the estimation of homography. One is an outdoor geographical labelling/overlaying system, and the other is an AR Pacman game application.