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Biomedical subjects

M Fuchs

Publications and source records attributed to M Fuchs.

At least 127 records · Page 7Linked to original sources
PubMed1995

GCAP-II: isolation and characterization of the circulating form of human uroguanylin.

The systematic isolation of circulating regulatory peptides which generate cGMP as second messenger resulted in the identification of a novel member of the guanylin family. In the present study we describe the purification and amino acid sequence of a new guanylate cyclase C activating peptide (GCAP-II). GCAP-II contains 24 amino acids in the following sequence: FKTLRTIANDDCELCVNVACTGCL. Its molecular mass is 2597.7 Da. The 16 C-terminal amino acids are identical to uroguanylin from human urine. native and synthetic GCAP-II activate GC-C, the specific guanylate cyclase receptor, of cultured human colon carcinoma (T84) cells. GCAP-II stimulates chloride secretion in isolated human intestinal mucosa mediated by intracellular cGMP increase. GCAP-II specific antibodies were used to localize the peptide by immunohistochemistry in entero-endocrine cells of the colonic mucosa.

Amino Acid Sequence↗
PubMed1995

Capillary electrophoresis-based immunoassay for cortisol in serum.

A competitive immunoassay for cortisol based on capillary electrophoresis (CE) and laser-induced fluorescence is described. The work involved the production of assay reagents and the development of separation conditions allowing for routine analysis of serum samples. Fluorescein-labeled cortisol was synthesized and purified. Fab fragments were produced from mouse monoclonal anticortisol antibody and purified using a POROS cation exchange chromatography column. After incubation of these reagents with serum, free and bound labeled antigen were separated by CE with high reproducibility. No prior sample cleanup of the serum samples was necessary. Serum calibration curves were established and used for the quantitation of cortisol in serum. The results demonstrate feasibility for a cortisol assay based on CE operating directly on serum samples.

Electrophoresis↗
PubMed1995

Origin of P16 median nerve SEP component identified by dipole source analysis--subthalamic or within the thalamo-cortical radiation?

Following median nerve stimulation, several monophasic peaks were recorded at the scalp in the 15-18 ms time range. Source analysis, using three different methods, modelled a source near the centre of the head with an orientation towards the activated hemisphere and a peak activity at 16 ms post stimulus. Magnetic recordings detected no signal in this time range, which confirmed a subcortical location of the source. From dipole localization it was not possible to assign the exact origin of the P16 source to either the subthalamic level or the thalamo-cortical radiation, because of the limited spatial resolution at the centre of the spherical head model. An estimate of the conduction velocity of the medial lemniscus pointed towards a subthalamic origin. The P16 source was preserved in two patients with a lesion of the thalamo-cortical radiation and the ventral thalamus. Further evidence for a subthalamic location of P16 was derived from the physical mechanisms generating far-field potentials.

Adult↗
PubMed1995

Comparison of realistically shaped boundary-element and spherical head models in source localization of early somatosensory evoked potentials.

Source localizations of early somatosensory evoked potentials and electrical potentials produced by dipoles in the region of the central sulcus were computed using realistically shaped boundary-element head models (BEM) and compared to localizations obtained using 3-shell spherical models. Realistically shaped 3-shell boundary-element-models were constructed on the basis of the individual anatomy obtained from 3D-MR-tomography in 6 subjects. Spherical head models were fitted to the actual locations of the electrodes and to the surface of the heads, respectively. Source locations calculated within the spherical head models differed by an average of 4 mm (range: 2 to 7 mm) with respect to the 3-shell BEM, taking into account the limited accuracy of this model. This mislocation was most prominently due to deeper source locations predicted using a spherical head model and caused by incorrect modelling of the geometry of the heads, although sources were located in a favourable region of the heads.

Adult↗
PubMed1995

Coordinate system matching for neuromagnetic and morphological reconstruction overlay.

The overlay of functional and morphological images is an essential tool for advanced and improved functional diagnosis showing the correlation between spatial structures or lesions and functional areas. We present an improved coordinate system matching technique. The well known method of three orthogonal coils combined in one coilset for an angular-independent measure is validated for the use of first- or higher order gradiometers instead of magnetometers. The coilset localization procedure was modified with lock-in detection and current feedback for better long range sensitivity. Real measurements with the 31-channel Philips-MEG system have been carried out. A very good localization accuracy below the measuring area with deviations below 2 mm was found. For coordinate system matching, a 3-D cursor with surface images from segmented MR-data was implemented and an optimized, weighted least squares fit transformation algorithm between functional and morphological systems was developed. The resulting transformations consist of weighted shifts and best-fit rotations and lead to deviations of marker positions in the mm range, depending mainly on the spatial accuracy of the marker fixation.

Algorithms↗
PubMed1995

The role of macrophage receptors in adhesion and uptake of Leishmania mexicana amastigotes.

Amastigotes of the protozoan parasite Leishmania proliferate in phagolysosomes of mammalian macrophages. Propagation of the infection is considered to occur by host-cell rupture and uptake of released parasites by uninfected macrophages. In this study, the kinetics of binding of L mexicana mexicana amastigotes to COS cells and to COS cells transfected with three different macrophage receptors (FcRII-B2, receptor for the Fc-domain of immunoglobulins; CR3, complement type 3 receptor and the mannose receptor) is compared to the rate of adhesion to peritoneal macrophages. Amastigotes isolated from macrophages cultivated in vitro bind with slow, sigmoid kinetics to COS cells expressing either of the three receptors, or to peritoneal macrophages. In contrast, amastigotes isolated from mouse lesions bind with rapid, hyperbolic kinetics to COS cells expressing the Fc receptor or to peritoneal macrophages but with slow, sigmoid kinetics to COS cells expressing the CR3 or the mannose receptor. As shown by immunofluorescence experiments, lesion-derived amastigotes contain host-derived immunoglobulins (Ig) but no complement component 3 at their surface. It is concluded that amastigotes contain no intrinsic ligand at their surface, which enables high-affinity interactions with macrophages. Opsonization by specific Ig may be of relevance in vivo because firstly, in cryosections of mouse lesions extracellular amastigotes containing surface Ig can be detected and, secondly, B cell-deficient mice reconstituted with parasite-specific Ig show a modest increase in the rate of lesion development. In addition, it is shown that amastigotes are internalized by COS cells and grow in large parasitophorous vacuoles similar to those observed in macrophages.

Adhesiveness↗
PubMed1995

[Effect of various methods of resection of the stomach in liberation of cholecystokinin, neurotensin and on pancreatic function].

In a follow up study 19 patients after Billroth-I, 22 patients after Billroth-II-resection and 38 patients after total gastrectomy (23 with Roux-Y-reconstruction and 15 with Longmire-Gütgemann) underwent a stool fat determination and an indirect pancreatic function test with fluorescein dilaurate in serum und urine. In 9 of 19 cases (47.3%) after B-I-resection and 14 of 22 patients (63.5%) after B-II-resection there were pathological results of the PLT-test in urine. After total gastrectomy as well with reconstruction of the duodenal passage as with its exclusion the PLT-test results were pathological in 60% resp. 87%. These results indicate a secondary pancreatic insufficiency following gastric resection.

Adult↗
PubMed1995

Solution-phase immunoassay for determination of cortisol in serum by capillary electrophoresis.

We describe a competitive solution-phase immunoassay for serum cortisol determination that involves capillary electrophoresis (CE) combined with laser-induced fluorescence for separation and quantification. A polyclonal antibody preparation and fluorescein-labeled cortisol are used as assay reagents. 8-Anilino-1-naphthalenesulfonic acid was added to the serum sample during the assay to promote the release of cortisol from endogenous binding proteins. Conditions for the rapid separation of free and bound labeled antigen by CE were developed. Aspects of assay performance are evaluated in this report. The resulting assay protocol allows for the analysis of serum samples without extraction or other sample preparation steps.

Anilino Naphthalenesulfonates↗