Biomedical subjects

Birgit Strobl

Publications and source records attributed to Birgit Strobl.

6 recordsLinked to original sources

PubMed2003

Of JAKs, STATs, blind watchmakers, jeeps and trains.

Janus kinase/signal transducer and activator of transcription (JAK/STAT) signalling is essential but not sufficient for full responses to the interferons (IFNs), most cytokines and some growth factors. The IFN-gamma and interleukin-6 (IL-6) response pathways have been used as model systems to investigate both the signals involved and their organisation. Activated STAT1 diffuses freely in the cytoplasmic and nuclear compartments of the cell providing a 'random walk' element in the IFN-gamma response. Completely foreign chimeric receptors and, remarkably, in the absence of STAT3, the endogenous IL-6 receptor can efficiently mediate an IFN-gamma-like response. Accordingly all of the signals required for an IFN-gamma response can be generated through physiological levels of a foreign ligand. JAK/STAT signalling, therefore, appears 'soft-wired', modular and highly flexible with substantial overlap between different response pathways. The data are consistent with a generic or 'core' set of signals from JAK/receptor complexes with 'add-on' modulation through specific receptor motifs. The cellular background likely profoundly affects the nature of the response.

Animals↗

PubMed2002

Cell-type and donor-specific transcriptional responses to interferon-alpha. Use of customized gene arrays.

A sensitive, specific, reproducible, robust, and cost-effective customized cDNA array system based on established nylon membrane technology has been developed for convenient multisample expression profiling for several hundred genes of choice. The genes represented are easily adjusted (depending on the availability of corresponding cDNAs) and the method is accordingly readily applicable to a wide variety of systems. Here we have focused on the expression profiles for interferon-alpha2a, the most widely used interferon for the treatment of viral hepatitis and malignancies, in primary cells (peripheral blood mononuclear cells, T cells, and dendritic cells) and cell lines (Kit255, HT1080, HepG2, and HuH7). Of 150 genes studied, only six were consistently induced in all cell types and donors, whereas 74 genes were induced in at least one cell type. IRF-7 was identified as the only gene exclusively induced in the hematopoietic cells. No gene was exclusively induced in the nonhematopoietic cell lines. In T cells 12, and in dendritic cells, 25 genes were induced in all donors whereas 45 and 42 genes, respectively, were induced in at least one donor. The data suggest that signaling through IFN-alpha2 can be substantially modulated to yield significant cell-type and donor-specific qualitative and quantitative differences in gene expression in response to this cytokine under highly standardized conditions.

Cell Line↗

PubMed2002

Mutational switch of an IL-6 response to an interferon-gamma-like response.

Signaling through Janus kinases (JAKs) and signal transducers and activators of transcription (STATs) is central to the responses to the majority of cytokines and some growth factors, including the interferons (IFNs) and the IL-6 family of cytokines. The biological responses to stimulation through the widely distributed IL-6 and IFN-gamma receptors are, however, completely different. Remarkably, it is shown here that, in mouse embryo fibroblasts lacking STAT3, IL-6 mediates an IFN-gamma-like response including prolonged activation of STAT1, the induction of multiple IFN-gamma-inducible genes, the expression of class II MHC antigens, and an antiviral state. Normal cells exposed to IL-6 thus require a STAT3-dependent function(s) to down-regulate STAT1 activity and prevent an IFN-gamma-like response. The data encourage the view that the very disparate IFN-gamma and IL-6 JAK/receptor complexes mediate a common set of generic or "core" signals which are subject to STAT3-dependent modulation to provide IL-6 specificity. The switching of one cytokine response to one closely mimicking another as a result of the loss of a single signaling component has profound implications, for example, for the interpretation of the phenotypes of knockout mice and for the clinical use of inhibitors of signaling.

Animals↗

PubMed2002

Aortic arch variation analyzed by using plastination.

Different ramification patterns can be observed during the development of the aortic arch. In this study a common trunk (CT), which subsequently branched into the brachiocephalic trunk (BT) and left common carotid artery (LCCA), arose from the aortic arch. The LCCA arose from the CT 10.27 mm above the aortic arch. After crossing the ventral aspect of the trachea and esophagus, the LCCA became situated on the left side of the esophagus. The caliber and length of the main branches of the aortic arch were determined and compared to reports in the literature. This variation was discovered in the context of producing transverse body slices using an E12 plastination process.

Aged↗

PubMed2002

Release of toxic metals from button batteries retained in the stomach: An in vitro study.

BACKGROUND: Ingestion of button batteries by children is a rapidly growing problem, and opinions differ on how button batteries distal to the gastroesophageal junction should be managed. The authors therefore performed an experimental study to determine the cumulative load of various toxic elements released from retained button cells in simulated gastric juice. METHODS: Eight different groups of button cells were immersed in simulated gastric juice. Analyzed elements included Al, Ba, Cd, Cr, Cu, Fe, Hg, Li, Mg, Mn, Ni, Pb, Sb, Sn, Sr, Te, TI, V, W; and Zn. Inductively coupled plasma mass spectrometry (ICP-MS) was used to evaluate the residual amounts of elements after 4, 24, 72, and 120 hours. RESULTS: At 4 hours, leakage was seen with almost all batteries, with the levels increasing in a time-dependent manner. The highest detected levels at 4 hours were 1.20 microgram for Cd, 280.51 ng for Hg, and 2.63 microgram for Pb. Dissolution, holes, and defragmentation were seen within 24 to 72 hours. Battery weight loss varied between 22 and 104 mg over the course of the study. CONCLUSIONS: Toxic elements contained in button cells are released quickly in gastric juice. This finding might change the current policy of watchful waiting or conservative management of batteries lodged in the stomach.

Electric Power Supplies↗

PubMed2002

The antiviral response to gamma interferon.

A role for alpha/beta interferon (IFN-alpha/beta) in the IFN-gamma antiviral response has long been suggested. Accordingly, possible roles for autocrine or double-stranded-RNA (dsRNA)-induced IFN-alpha/beta in the IFN-gamma response were investigated. Use was made of wild-type and a variety of mutant human fibrosarcoma cell lines, including mutant U5A cells, which lack a functional IFN-alpha/beta receptor and hence an IFN-alpha/beta response. IFN-gamma did not induce detectable levels of IFN-alpha/beta in any of the cell lines, nor was the IFN-gamma response per se dependent on autocrine IFN-alpha/beta. On the other hand, a number of responses to dsRNA [poly(I). poly(C)] and encephalomyocarditis virus were greatly enhanced by IFN-gamma pretreatment (priming) of wild-type cells or of mutant cells lacking an IFN-alpha/beta response; these include the primary induction of dsRNA-inducible mRNAs, including IFN-beta mRNA, and, to a lesser extent, the dsRNA-mediated activation of the p38 mitogen-activated protein (MAP) kinase(s). IFN-gamma priming of mRNA induction by dsRNA is dependent on JAK1 and shows biphasic kinetics, with an initial rapid (<30-min) response being followed by a more substantial effect on overnight incubation. The IFN-gamma-primed dsRNA responses appear to be subject to modulation through the p38, phosphatidylinositol 3-kinase, and ERK1/ERK2 MAP kinase pathways. It can be concluded that despite efficient priming of IFN-beta production, the IFN-alpha/beta pathways play no significant role in the primary IFN-gamma antiviral response in these cell-virus systems. The observed IFN-gamma priming of dsRNA responses, on the other hand, will likely play a significant role in combating virus infection in vivo.

Antiviral Agents↗