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Biomedical subjects

M Fuchs

Publications and source records attributed to M Fuchs.

At least 109 records · Page 6Linked to original sources
PubMed1996

Antigen presentation by Leishmania mexicana-infected macrophages: activation of helper T cells by a model parasite antigen secreted into the parasitophorous vacuole or expressed on the amastigote surface.

Leishmania are protozoan parasites which invade mammalian macrophages and multiply as amastigotes in phagolysosomes (parasitophorous vacuoles). Using L. mexicana and bone marrow-derived macrophages (BMM), the question is addressed whether infected BMM induced to express major histocompatibility complex class II molecules can present defined antigens to specific T helper type 1 cells. As a model antigen, a membrane-bound acid phosphatase (MAP), a minor protein associated with intracellular vesicles in amastigotes, was either overexpressed at the surface of the parasites or overexpressed in a soluble form leading to antigen secretion into the parasitophorous vacuole. Presentation of MAP epitopes by these three types of amastigotes was then compared for macrophages containing live parasites or amastigotes inactivated by drug treatment. It is shown that surface-exposed and secreted MAP can be efficiently presented to T cells by macrophages harboring live amastigotes. Therefore, the parasitophorous vacuole communicates by vesicular membrane traffic with the plasmalemma of the host cell. The intracellular MAP of wild-type cells or the abundant lysosomal cysteine proteinases are not or only inefficiently presented, respectively. After killing of the parasites, abundant proteins such as overexpressed MAP and the cysteine proteinases efficiently stimulate T cells, while wild-type MAP levels are not effective. We conclude that intracellular proteins of intact amastigotes are not available for presentation, while after parasite inactivation, presentation depends on antigen abundance and possibly stability. The cell biological and possible immunological consequences of these results are discussed.

Animals↗
PubMed1996

[Women in dermatology. German and other European clinics in a comparison].

The situation of women in dermatology was evaluated with the aid of questionnaires in spring 1994. A questionnaire was sent to 33 clinics in Germany and 46 in other European countries, asking about the proportions of male and female physicians in each department. In addition, individual department members were asked in another questionnaire about their reasons for choosing dermatology and about possible sex discrimination. The clinic questionnaires were returned from 22 German and 37 other European clinics and the individual questionnaires by 548 German physicians and 1164 physicians from the other countries (overall 52% women). We found that 41.8% of the dermatologists in German clinics were women, as against 43.4% in the other countries. Women made up about half of the fully qualified specialists, but accounted for only a small percentage of those in higher positions (10.8% in Germany, 27.9% in other countries). Of the 1712 physicians who answered the individual questionnaire, the majority had chosen dermatology because of their interest in the specialty. Slightly more women than men gave other reasons, such as more free time--mostly for family matters--or less physical strain. Clearly more women than men felt they were discriminated against professionally because of their sex. The reasons for this related primarily to the biological and social role of women in society. Overall, women are thus well represented in our specialty, except in leading positions.

Career Choice↗
PubMed1996

[HPV-5 typing with nested PCR and sequencing in epidermodysplasia verruciformis].

We report a case of epidermodysplasia verruciformis (EV) with typical cutaneous manifestations in light-exposed areas. The diagnostic criteria were the characteristic macular lesions, the virus transformed keratinocytes on histological examination and the detection of human papillomavirus (HPV) DNA by a nested-PCR approach for EV-associated types. In this case we found HPV-type 5, the most common type of HPV in EV, directly by sequencing and sequence analysis.

Adult↗
PubMed1996

Isolation and developmental expression analysis of Enx-1, a novel mouse Polycomb group gene.

Members of the Polycomb group (Pc-G) of genes encode transcriptional regulators that control the expression of key developmental effector genes in Drosophila melanogaster. Although multiple Pc-G genes have been identified and characterized in Drosophila, information about these important regulatory proteins in vertebrates, including their precise expression patterns, has remained scarce. We report here the cloning of Enx-1, a novel vertebrate Pc-G gene, which encodes the murine homolog of the Drosophila Enhancer of zeste (E(z)) gene. Drosophila E(z) controls the expression of several homeobox genes as well as some segmentation genes and its disruption causes multiple phenotypes in Drosophila development. Analysis of the primary structure of murine Enx-1 reveals the conservation of several regions, including the previously described SET domain and a newly defined CXC domain. In addition, we find the SET domain to be conserved in evolutionarily distant species ranging from vertebrates to plants and fungi. The expression pattern analysis of Enx-1 reveals ubiquitous expression throughout early embryogenesis, while in later embryonic development Enx-1 expression becomes restricted to specific sites within the central and peripheral nervous system and to the major sites of fetal hematopoiesis. In adult stages we also find Enx-1 expression to be restricted to specific tissues, including spleen, testis and placenta.

Amino Acid Sequence↗
PubMed1996

Feedback regulation of bile acid synthesis measured by stable isotope kinetics in humans.

OBJECTIVE: To investigate the effect of a low dose of exogenous bile acids and a non-absorbable antibiotic on bile acid kinetics in healthy human subjects. METHODS: Pool size, synthesis rate and fractional turnover rate of the three main bile acids were determined simultaneously with stable isotope labelled bile acids in volunteers before and during intake of 500 mg cholic acid (n = 6), chenodeoxycholic acid (n = 6) or deoxycholic acid (n = 5) per day for 4 weeks or 1 g of paromomycin (n = 6) per day for 2 weeks. RESULTS: Administration of cholic acid nearly doubled the input and pool of deoxycholic acid; chenodeoxycholic acid synthesis was inhibited by 38% and pool size was reduced by 50%. Deoxycholic acid administration resulted in a suppression of both cholic acid and chenodeoxycholic acid synthesis by 53%; the corresponding pool sizes were reduced by 64% and 57%, respectively. The degree of suppression of chenodeoxycholic acid synthesis correlated significantly (P < 0.001) with the relative change of deoxycholic acid input and pool size. Oral chenodeoxycholic acid resulted in an inhibition of cholic acid synthesis (65%) and deoxycholic acid input (67%). The effects of the antibiotic were variable. CONCLUSION: The suppressive effect of cholic acid may be mediated by deoxycholic acid, which is nearly as effective as chenodeoxycholate.

Administration, Oral↗
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↗