In vivo MR evaluation of Gd-DTPA conjugated to dextran in normal rabbits.

A dextran-Gd-DTPA compound has been recently synthesized utilizing 70,800 Da molecular weight dextran. This polymeric contrast agent for magnetic resonance imaging has been found chemically to be very stable and to demonstrate in vitro improved relaxivities of 1.5 to 2.3 times that of monomeric Gd-DTPA at 100 MHz. This MR experiment examines the in vivo distribution and relaxivity of the 70,800 Da molecular weight dextran-Gd-DTPA compound in a rabbit model by measuring the change in signal-to-noise ratio of a variety of organs (renal cortex, renal medulla, liver, brain, and torcula herophile) compared to the preinjection state. Results demonstrate prolonged (beyond 60 min) enhancement of the renal cortex, renal medulla, liver and torcula, and no enhancement of brain parenchyma.     

Measurement of theZ0 line shape parameters and the electroweak couplings of charged leptons

We report on an improved measurement of the mass of theZ ⁰ boson, its total width and its partial decay widths into hadrons and leptons, as well as the effective axial vector and vector couplings to charged leptons. These measurements are based on a data set of approximately 160 000 hadronicZ ⁰ decays and 18 000 decays into electrons, muons and taus, recorded by the OPAL experiment at centre of mass energies near the mass of theZ ⁰. The total width and the partial widths to visible final states, derived from the measured cross sections, are used to extract the invisible width. The effective couplings of theZ ⁰ to charged leptons are studied using measurements of the lepton pair cross sections and forward-backward asymmetries at the different centre of mass energy points of theZ ⁰ scan. The implications of our results in the context of the Standard Model are discussed.On leave from Research Institute for Computer Peripherals, Hangzhou, China     

On the electric current from electrodes in a magnetized semiconductor film

The problem on the electric current from electrodes in a magnetizedsemiconductor film is reduced to the skew derivative problemfor the Laplace equation outside cuts in a plane. The problemfor the Laplace equation is studied under different conditionsat infinity, which have a certain physical meaning. With thehelp of potential theory, the skew derivative problem is reducedto a Fredholm integral equation of the second kind, which isuniquely solvable. The Neumann problem for the Laplace equationin the exterior of cuts in a plane is a particular case of ourproblem.     

Conditions for separately subharmonic functions to be subharmonic

Letu be a function on ^m × ⁿ , wherem2 andn2, such thatu(x, .) is subharmonic on ⁿ for each fixedx in ^m andu(.,y) is subharmonic on ^m for each fixedy in ⁿ . We give a local integrability condition which ensures the subharmonicity ofu on ^m × ⁿ , and we show that this condition is close to being sharp. In particular, the local integrability of (log⁺ u ⁺) ^m+n–2+ is enough to secure the subharmonicity ofu if >0, but not if <0.     

A recoverable enzymatic microgel based on biomolecular recognition

The enzyme beta-galactosidase has been immobilized through incorporation into a selectively soluble microgel, prepared from DNA, biotinylated peptide nucleic acid (PNA), and the protein avidin. The enzyme was conjugated to avidin, allowing it to be integrated directly into the microgel network. Efficient hydrolysis of a small-molecule substrate occurred at 37 degrees , but cooling and centrifuging led to precipitation of the microgels and product separation. The microgels were then reconstituted by adding fresh buffer and shaking. The enzymatic activity was completely recovered through repeated cycles. This method should be generalizable to a wide variety of other enzymes and substrates.     

THE SULFUR (11)-NITROGEN BOND. PART IV1. AMINOSULFENATES

Abstract

Aminosulfenates R₂NSOR' have been prepared from aminosulfenyl chlorides and tin alkoxides. They form sulfenyl chlorides with chlorosilanes, bisaminosulfides with secondary amines and polysulfides with thiols.     

Fragmentation of negative ions from N‐linked carbohydrates,Part 4. Fragmentation of complex glycans lacking substitution on the 6‐antenna

Negative ion CID spectra of N‐linked glycans released from glycoproteins contain many ions that are diagnostic for specific structural features such as the detailed arrangement of antennae and the location of fucose residues. Identification of such ions requires reference glycans that are often difficult to acquire in a pure state. The recent acquisition of a sample of N‐glycans from a patient lacking the enzyme N‐acetylglucosaminyltransferase‐2 provided an opportunity to investigate fragmentation of glycans lacking a 6‐antenna. These glycans contained one or two galactose‐N‐acetylglucosamine‐chains attached to the 3‐linked mannose residue of the trimannosyl‐chitobiose core with and without fucose substitution. The spectra from the patient sample clearly defined the antenna distribution and showed striking differences from the spectra of isomeric compounds obtained from normal subjects. Furthermore, they provided additional information on previously identified antenna‐specific fragment ions and indicated the presence of additional ions that were diagnostic of fucose substitution. Glycans obtained from such enzyme‐deficient patients can, thus, be a valuable way of obtaining spectra of specific isomers in a relatively pure state for interpretation of mass spectra. Copyright © 2010 John Wiley & Sons, Ltd.