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J Wessendorf

Publications and source records attributed to J Wessendorf.

6 recordsLinked to original sources
PubMed2002

Antigen-presenting cells and tolerance induction.

T cell tolerance induction to foreign and self-antigens has occupied research since the beginning of the understanding of the immune system. Much controversy still exists on this question even though new methods became available to investigate immunoregulatory mechanisms. Antigen-presenting cells play a pivotal role in transferring information from the periphery of the organism to lymphoid organs. There, they initiate not only the activation of naive T cells but seem to deliver important signals which result in T cell unresponsiveness with antigen-specific tolerance induction.

Animals↗
PubMed1994

Induction of cyclooxygenase-2 by interleukin-1 alpha. Evidence for post-transcriptional regulation.

Prostanoids, produced by diverse cell types, modulate a variety of pathophysiological processes. The rate of prostanoid synthesis is determined, in part, by the levels of prostanoid-synthetic enzymes, such as cyclooxygenase (Cox), a rate-limiting enzyme in the conversion of arachidonic acid to prostanoids. While two Cox genes have been identified, Cox-2 is unique because it is highly induced in response to cell activation processes including inflammation. We have studied the effect of interleukin-1 alpha (IL-1 alpha), a proinflammatory cytokine that facilitates its actions in part by inducing the synthesis of prostanoids, on the expression of Cox-2 in a human cell line (ECV304) and demonstrated that IL-1 alpha induces a sustained increase in the expression of the Cox-2 mRNA as well as the functional enzyme. Three mechanistically distinct inhibitors of translation stimulated the expression of the Cox-2 mRNA and potentiated the effect of IL-1 alpha. Furthermore, IL-1 alpha induced rapid but transient activation of Cox-2 transcription and, in the absence of transcription, prolonged the half-life of the Cox-2 mRNA. Together, these data suggest that post-transcriptional mechanisms are important in the sustained induction of the Cox-2 mRNA and that IL-1 alpha may increase the stability of the Cox-2 transcript.

Base Sequence↗
PubMed1992

Interleukin-1 alpha mediates an alternative pathway for the antiproliferative action of poly(I.C) on human endothelial cells.

The antiproliferative effect of double-stranded RNA (dsRNA) on human tumor and normal cells has been well established. However, the genes involved in the dsRNA-induced antiproliferative response and the molecular mechanisms by which this occurs remain less well defined. We have studied the ability of synthetic dsRNA, polyinosinic:polycytidylic acid (poly(I.C)) to modify human umbilical vein endothelial cell (HUVEC) growth and report that poly(I.C) induces a dose-dependent inhibition of HUVEC proliferation in vitro. In addition, the mRNA levels for the cytokines interleukin-1 alpha (IL-1 alpha) and interferon-beta 1 are induced in poly(I.C)-treated cells. Moreover, the growth inhibitory effects of poly(I.C) are relieved when cells are grown in the presence of an IL-1 alpha antisense oligonucleotide to the human IL-1 alpha transcript. Thus, the effects of poly(I.C) appear to be mediated, in part, through the function of IL-1 alpha, suggesting an alternative pathway for dsRNA-mediated inhibition of human endothelial cell growth.

Base Sequence↗
PubMed1985

Degradation of lawsone by Pseudomonas putida L2.

From humus obtained from Stuttgart, a bacterium was isolated with lawsone (2-hydroxy-1,4-naphthoquinone) as selective source of carbon. This bacterium is capable of utilizing lawsone as sole source of carbon and energy. Morphological and physiological characteristics of the bacterium were examined and it was identified as a strain of Pseudomonas putida. The organism is referred to as Pseudomonas putida L2. The degradation of lawsone by Pseudomonas putida L2 was investigated. Salicylic acid and catechol were isolated and identified as metabolites. In lawsone-induced cells of Pseudomonas putida L2, salicylic acid is converted to catechol by salicylate 1-monooxygenase. Catechol 1,2-dioxygenase catalyses ortho-fission of catechol which is then metabolized via the beta-ketoadipate pathway. Formation of cis,cis-muconate and beta-ketoadipate was demonstrated by enzyme assays. Salicylate 1-monooxygenase and catechol 1,2-dioxygenase are induced sequentially. The enzymes of the beta-ketoadipate pathway are also inducible. Naphthoquinone hydroxylase, however, was demonstrated in induced and non-induced cells. This constitutive enzyme enables Pseudomonas putida L2 to degrade various 1,4-naphthoquinones in experiments with resting cells.

Biotransformation↗