PubMed Health⌕ Search

Biomedical subjects

H Dinter

Publications and source records attributed to H Dinter.

11 recordsLinked to original sources
PubMed1997

Inhibition of tumour necrosis factor production in endotoxin-stimulated human mononuclear leukocytes by the prostacyclin analogue iloprost: cellular mechanisms.

The prostacyclin analogue iloprost has been shown to inhibit effectively TNF-alpha production in human peripheral blood mononuclear leukocytes (PBMC) stimulated with bacterial lipopolysaccharide (LPS). The current paper set out to analyse further the possible mechanisms involved in the regulation of TNF-alpha synthesis by iloprost. Healthy human PBMC were challenged with Escherichia coli LPS and assessed for TNF-alpha gene transcription, mRNA stability and protein secretion. Iloprost reduced both steady-state TNF-alpha mRNA expression and protein release as assessed by Northern blot analysis, polymerase chain reaction and enzyme immunoassay. This effect was related both to a reduction of TNF-alpha transcriptional activity (as evaluated by nuclear run-on transcription analysis) and a decrease in TNF-alpha mRNA stability (as assessed by serial Northern blot analysis of TNF-alpha mRNA content in PBMC blocked with actinomycin D). When collectively assessed, these data demonstrate that iloprost regulates TNF-alpha synthesis at both transcriptional and post-transcriptional level.

Cells, Cultured↗
PubMed1997

Phosphodiesterase type IV inhibitors in the treatment of multiple sclerosis.

Multiple sclerosis is an autoimmune disease with inflammatory lesions localized to the white matter of the central nervous system. Early on, the disease is characterized by episodes of exacerbations and remissions. During exacerbations there is an acute inflammatory infiltrate characterized by the presence of mononuclear cells, monocytes, and T lymphocytes. These cells produce proinflammatory cytokines that have been implicated in the amplification of the inflammatory response as well as in the damage of oligodendrocytes. The inflammation ultimately results in loss of myelin and oligodendrocyte cell death (demyelination). Thus therapies aimed at preventing the inflammatory response may have a beneficial effect on the course of the disease. One such therapy is treatment with inhibitors of phosphodiesterase type IV. These drugs have proven to be extremely effective in the prevention and treatment of experimental allergic encephalomyelitis, the animal model for multiple sclerosis. These experiments, as well as other data discussed here, provide a rationale for the treatment of multiple sclerosis with inhibitors of phosphodiesterase type IV.

Animals↗
PubMed1995

Splice variants of the human EP3 receptor for prostaglandin E2.

The EP3 receptor for prostaglandin E2 (PGE2) mediates various biological activities such as uterine contraction, inhibition of gastric acid secretion, presynaptic inhibition of neurotransmitter release and potentiation of platelet aggregation. In an attempt to understand the molecular basis of this diversity of biological function, we cloned full-length cDNAs encoding EP3 receptors for PGE2 from human uterus cDNA libraries. Seven cDNA variants were identified which code for six distinct EP3-receptor isoforms. Sequencing revealed that the receptor isoforms differ in their intracellular C-terminal domains. Southern blot experiments indicate that the isoforms are generated by alternative splicing. The EP3-receptor gene is expressed in various tissues with high expression in kidney and pancreas, as demonstrated by Northern blot analysis. All receptors, stably expressed in baby hamster kidney (BHK) cells, bind PGE2 specifically with similar Kd of 2.2-5.8 nM. The binding of [3H]PGE2 is competed with by unlabelled prostaglandins in the order sulprostone (a PGE2-like agonist) approximately PGE2 >> PGF2 alpha > Iloprost (a prostacyclin analogue) > PGD2, which is specific for EP3 receptors. Analysis of the signal-transduction pathways demonstrated that all receptors respond with inhibition of forskolin-induced cAMP accumulation with an IC50 of 0.1-3 nM PGE2. In addition, some isoforms induce an increase in intracellular free calcium ([Ca2+]i) at PGE2 concentrations greater than or equal to 10 nM. These results may offer an explanation for the different physiological responses observed in various tissues following activation of EP3 receptors.

Amino Acid Sequence↗
PubMed1992

High-level secretion of the four salivary plasminogen activators from the vampire bat Desmodus rotundus by stably transfected baby hamster kidney cells.

The cDNAs coding for the four Desmodus rotundus salivary plasminogen activators (DSPAs) were subcloned into the mammalian expression vector, pMPSV/CMV, which carries the myeloproliferative sarcoma virus promoter and the cytomegalovirus enhancer. These constructs were transfected, together with plasmids harbouring Geneticin (G418)-resistance and puromycin-resistance genes, into baby hamster kidney cells. Through the selective pressure of both antibiotics, cell clones constitutively overexpressing the DSPA alpha 1, DSPA alpha 2, DSPA beta or DSPA gamma cDNAs were obtained. Secretion of active DSPAs was confirmed by zymographic analysis and quantified using a fibrin plate assay and ELISA.

Animals↗
PubMed1987

In vitro activation of the HIV-1 enhancer in extracts from cells treated with a phorbol ester tumor promoter.

The transition from persistent to lytic infection by the human immunodeficiency virus, HIV, is marked by a burst of viral replication and gene expression that occurs when infected cells are stimulated by physiological inducers or tumor promoters like 12-O-tetradecanoyl phorbol acetate (TPA). We report here that the HIV enhancer is activated specifically by TPA in several non-lymphoid cell types, and that this transcriptional regulation can be reproduced in a cell-free system. In vitro transcription experiments revealed a 6-fold activation of the HIV promoter in nuclear extracts prepared from TPA-induced HeLa tk- cells, whereas a control (human alpha-globin) promoter was transcribed with equal efficiency in either induced or uninduced cell extracts. A corresponding increase in the activity of a cellular DNA-binding protein that interacts with the HIV enhancer was detected in TPA-treated cells with DNase I footprint experiments. This increase occurred in the absence of de novo protein synthesis, suggesting a post-transcriptional activation mechanism. Analysis of HIV deletion mutants suggests that the enhancer is the target for the TPA effect both in vitro and in vivo. The cell-free system described here should facilitate studies on the mechanism of phorbol ester induction of gene-specific transcription factors.

Cell Line↗
PubMed1987

Cooperative interaction of multiple DNA elements in the human interferon-beta promoter.

Analysis of promoter mutants and hybrids in permanently transformed murine L cells reveals several regulatory DNA sequence elements in the 5' flanking region of the human interferon-beta gene, which together constitute the inducible promoter. The elements consist almost exclusively of purine runs in the region -111 to -1. Deletion of single elements reduces the expression capacity drastically, whereas duplication leads to a synergism of inducible expression. These elements act together in a cooperative way to achieve high inducibility. Natural and mutant promoter fragments containing these elements impose inducibility on a heterologous promoter. However, typical enhancer activity in this system is not observed.

Animals↗
PubMed1987

Superinduction of the human interferon-beta promoter.

Superinduction, that is induction with simultaneous blocking of mRNA translation, enhances the induction of interferon-beta in response to virus or double-stranded RNA in human fibroblasts. Expression of the cloned IFN-beta gene upon transfer into heterologous cells reflects the endogeneous interferon expression with respect to induction or superinduction indicating the involvement of cellular mediators in this mode of gene regulation. Expression from gene hybrids in mouse Mo57/2 cells reveals that 5' flanking DNA sequences from the human IFN-beta gene are responsible for induction and superinduction. Superinduction of the human IFN-beta promoter is demonstrated in several rodent and primate cell lines. In addition, expression from promoter mutants in mouse cells indicates that DNA sequences responsible for induction and superinduction are identical.

Animals↗