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Biomedical subjects

D Dudziak

Publications and source records attributed to D Dudziak.

5 recordsLinked to original sources
PubMed2001

The extracellular domain of CD83 inhibits dendritic cell-mediated T cell stimulation and binds to a ligand on dendritic cells.

CD83 is an immunoglobulin (Ig) superfamily member that is upregulated during the maturation of dendritic cells (DCs). It has been widely used as a marker for mature DCs, but its function is still unknown. To approach its potential functional role, we have expressed the extracellular Ig domain of human CD83 (hCD83ext) as a soluble protein. Using this tool we could show that immature as well as mature DCs bind to CD83. Since CD83 binds a ligand also expressed on immature DCs, which do not express CD83, indicates that binding is not a homophilic interaction. In addition we demonstrate that hCD83ext interferes with DC maturation downmodulating the expression of CD80 and CD83, while no phenotypical effects were observed on T cells. Finally, we show that hCD83ext inhibits DC-dependent allogeneic and peptide-specific T cell proliferation in a concentration dependent manner in vitro. This is the first report regarding functional aspects of CD83 and the binding of CD83 to DCs.

Antigen Presentation↗
PubMed2001

Antagonistic effects of c-myc and Epstein-Barr virus latent genes on the phenotype of human B cells.

Epstein-Barr virus (EBV) immortalized cells and Burkitt lymphoma cells have a completely different growth pattern and phenotype. EBV immortalized cells express a set of 11 viral genes to accommodate B cell activation and proliferation, whereas EBV-positive Burkitt lymphoma cells highly express the c-myc oncogene that is activated through translocation into 1 of the immunoglobulin loci and EBNA1 as the only viral protein. We have developed a primary human B cell line conditionally immortalized by Epstein-Barr virus in which the viral gene program responsible for the induction of proliferation can be switched on and off by the addition or withdrawal of estrogen (cell line EREB2-5). Starting from this cell line we have generated 2 daughter cell lines that proliferate in a c-myc dependent fashion, 1 with a highly active exogenous c-myc gene (cell line A1) and 1 with a regulatable c-myc gene that can be switched on by withdrawal and switched off by addition of tetracycline (cell line P493-6). The comparison of the 3 cell lines has allowed us to dissect the contribution of c-myc and EBV genes to the regulation of the growth pattern and expression of cell surface molecules. We show that MYC and EBNA2 (and their respective target genes) have opposing effects on the expression of several surface markers involved in B cell activation. We show that MYC contributes to the phenotype of Burkitt lymphoma cells by upregulating CD10 and CD38 and downregulating activation markers. The phenotype of the cells is determined on one hand by the absence of the viral gene products EBNA2 and LMP1 that mediate the phenotype of activated lymphoblasts and to a lesser extent by an active contribution of the c-myc gene.

ADP-ribosyl Cyclase↗
PubMed1999

[Investigations on the dependence of hematologic and blood chemical parameters on the age of health lambs--a contribution to the definition of reference values in sheep].

Haematological and biochemical examinations were carried out in 284 clinically healthy lambs aged from birth to nine month. The 122 male and 164 female animals belonged to the following breeds: German blackheaded mutton sheep (n = 114), Merino (n = 21), Frisian milksheep (n = 98), Texel (n = 31), Bentheimer landrace (n = 16) and Leine sheep (n = 5). The lambs were selected from a larger number of probationers by use of outlier tests. No differences were found between sexes for any of examined parameters. For the period from two to eight weeks of age breed differences could be proven for glutamate dehydrogenase and creatinin. Many parameters showed a strong dependence on the age of the lambs in a linear or polynomial function. While lymphocytes, protein, urea, creatinin, 3-hydroxybutyrate and copper increased, bilirubin, glucose, calcium, inorganic phosphate and the activities of alkaline phosphatase and gamma-glutamyl-transferase decreased with age. Body weight had no influence on any examined parameter within the age dependence. Reference values (limits) are defined for healthy lambs and for healthy ewes, summarized from former studies.

Aging↗
PubMed1995

[Treatment of swine with chronic pneumonia with chlortetracycline-medicated feed].

26 fattening pigs with spontaneous severe chronic bronchopneumonitis were orally treated with feed containing 800 ppm chlortetracycline (CTC) over 3 weeks. With the help of clinical investigation, transcutaneous measurement of the oxygen-saturation of the blood, X-ray of the thorax and bronchoalveolar lavage significant effects could be measured during and after finishing the treatment. In 19 spontaneous fallen ill untreated control animals recovery could not be detected by the used methods. After the end of the 3 weeks interval there were significant differences between treated and untreated animals detectable. By this investigations practical observations that oral treatment with 800 ppm in fattening pigs is effective was verified. But because of pharmacokinetic data higher concentrations would be recommendable. In the treated pigs a significant increase of the oxygen saturation of the blood occurred not before the 8th day of treatment. This underlines the importance of sufficient length of the treatment interval.

Administration, Oral↗