Biomedical subjects

C Schwer

Publications and source records attributed to C Schwer.

7 recordsLinked to original sources

PubMed1998

Characterization of the F(ab')2 fragment of a murine monoclonal antibody using capillary isoelectric focusing and electrospray ionization mass spectrometry.

We characterized a F(ab')2 fragment obtained by pepsin cleavage from a murine monoclonal IgG3 by means of electrospray ionization (ESI) mass spectrometry (MS), capillary isoelectric focusing (cIEF), high-performance anion-exchange chromatography-pulsed amperometric detection (HPAEC-PAD) and LC-MS peptide mapping. Separation of the fragment by cIEF under nonreducing conditions resulted in a number of distinct peaks. Using reducing conditions the heavy chain and the light chain were separated into two peaks each. Analysis by ESI-MS revealed a high mass heterogeneity of the molecule. Digestion with neuraminidase simplified both the cIEF pattern and the mass spectrum. The cIEF of the reduced molecule showed that the sialic acids were located only on the heavy chain of the F(ab')2-fragment. By incubation with O-glycosidase a further reduction of the complexity of the mass spectrum was achieved showing 8 different isoforms. By LC-MS peptide mapping these isoforms could be attributed to the heterogeneity of the pepsin cleavage site in the hinge region of the antibody. The sugars of the O-linked carbohydrate chain were identified by HPAEC-PAD as galactosyl-N-acetyl-galactosamine (GalNAcGal) with terminal N-glycolylneuraminic acid. The glycosylation site was identified by peptide mapping and amino acid sequence analysis as Ser222.

Amino Acid Sequence↗

PubMed1996

Quantitative competitive polymerase chain reaction: analysis of amplified products of the HIV-1 gag gene by capillary electrophoresis with laser-induced fluorescence detection.

A quantitative competitive polymerase chain reaction (PCR) assay for the detection and quantification of HIV-1 has been developed using capillary electrophoresis. Separation of the PCR products is carried out in coated capillaries filled with replaceable linear polyacrylamide, and detection is performed using laser-induced fluorescence. The quantitative capabilities of this assay are described. We show results from analysis of a noninfectious plasmid encoding the HIV genome and integrated proviral DNA. Potential applications of this assay are discussed.

Cell Line↗

PubMed1995

Capillary isoelectric focusing: a routine method for protein analysis?

Although isoelectric focusing (IEF) in the slab gel format is a widely used technique in protein analysis, capillary isoelectric focusing (CIEF) is not yet a method used routinely, despite major advantages. This may be due to the fact that several methods for performing IEF in the capillary can be found in the literature, differing in the manner of mobilizing the focused protein zones for detection. We therefore discuss and compare the three most widely used CIEF techniques - using chemical, pressure, or electroosmotic flow (EOF) mobilization - with respect to linearity of the calibration curve, resolution, and reproducibility.

Electrophoresis, Capillary↗

PubMed1994

Purification, crystallization and preliminary X-ray diffraction analysis of recombinant human neutrophil-activating peptide 2 (rhNAP-2).

The potent activator and chemoattractant for human neutrophils, neutrophil-activating peptide 2 (NAP-2), has been cloned and expressed in Escherichia coli. The protein has been purified to homogeneity (> 98%) by a series of chromatographic techniques, including reversed phase HPLC. The biological activity of recombinant human NAP-2 (rhNAP-2), characterized by the induction of elastase release from human neutrophils, was found to be comparable to natural NAP-2. rhNAP-2 has been crystallized by the hanging drop vapor diffusion method. The crystals belong to space group P222 with unit cell dimensions of a = 30.8 A, b = 39.5 A and c = 95.3 A. A packing density of 3.8 A3/Da with a solvent content of approximately 68% is obtained when one molecule per asymmetric unit is assumed. The crystals were shown to diffract to beyond 2.0 A on a conventional X-ray source. They are stable to X-rays for several days and are thus suitable for high resolution structure determination.

Amino Acid Sequence↗

PubMed1992

Analytical and micropreparative separation of peptides by capillary zone electrophoresis using discontinuous buffer systems.

The tiny injection volumes that are usually necessary to maintain the high efficiency of capillary zone electrophoresis present a major problem if only limited sample amounts are available. To increase the sample load, discontinuous buffer systems were developed that allow the on-column concentration of dilute samples. Injection volumes can be increased in this way by at least a factor of 30. These stacking systems were applied to the analysis of tryptic peptides, to the purity checking of high-performance liquid chromatographic fractions and for the micropreparative separation of peptides with subsequent amino acid sequence analysis.

Amino Acid Sequence↗

PubMedDate not supplied

Determination of 1,2,4-trimethylbenzene (pseudocumene) in serum of a person exposed to liquid scintillation counting solutions by GC/MS.

1,2,4-Trimethylbenzene (pseudocumene) is often used as the solvent for liquid scintillation counting solutions. In the present work, the determination of 1,2,4-trimethylbenzene in the serum of a person exposed to the solvent vapor during the handling of liquid scintillation counting cocktails is described. The identification of 1,2,4-trimethylbenzene was carried out by GC/MS. The analyte was quantified by GC with flame ionization detection. The detection limit of the method is 0.01 ppm. Two hours after exposure of a person to the solvent vapor, the concentration of 1,2,4-trimethylbenzene in her serum was found to be 0.20 ppm.

Benzene Derivatives↗

PubMedDate not supplied

A simple superimposition method for anatomical adjustments of CT and SPECT images.

A technique for superimposition of CT and single photon emission CT (SPECT) images is described. Regions of interest can be placed on SPECT images and projected to CT images. In this way, anatomical registration of regions of increased or decreased activity is possible. The equipment is easy to handle and available at low cost.

Humans↗