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Biomedical subjects

G Neurauter

Publications and source records attributed to G Neurauter.

6 recordsLinked to original sources
PubMed2004

PADMA 28 modulates interferon-gamma-induced tryptophan degradation and neopterin production in human PBMC in vitro.

Tibetan herbal remedy PADMA 28 revealed promising results to support treatment of intermittent claudication, atherosclerosis and chronic hepatitis. The remedy was confirmed to be closely linked with anti- and pro-oxidative properties in vitro. In this study, effect of PADMA 28 was investigated in stimulated and unstimulated human peripheral blood mononuclear cells (PBMC) in vitro. Neopterin production and tryptophan degradation were measured in supernatants of PBMC in the presence or absence of mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A). Stimulation of PBMC induced neopterin formation and tryptophan degradation (p<0.001 compared to unstimulated PBMC), and PADMA 28 inhibited both immunobiochemical effects (p<0.001) in a concentration-dependent manner. Higher concentrations of PADMA 28 were more effective and were able to completely block the pathways induced upon mitogenic stimulation. Data allow to conclude that PADMA 28 is able to inhibit immunobiological effects in stimulated PBMC in vitro. The suppression of neopterin production and tryptophan degradation suggests a specific influence on biochemical pathways induced by Th1-type cytokine interferon-gamma.

Cells, Cultured↗
PubMed2003

Atorvastatin suppresses interferon-gamma -induced neopterin formation and tryptophan degradation in human peripheral blood mononuclear cells and in monocytic cell lines.

Inhibitors of 3-hydroxy-3methylglutaryl-co-enzyme A (HMG-CoA) reductase, so-called statins, are used in medical practice because of their lipid-lowering effect and to reduce the risk of coronary heart disease. Recent findings indicate that statins also have anti-inflammatory properties and can modulate the immune response. In vitro, we investigated the effect of atorvastatin on the T cell/macrophage system in peripheral blood mononuclear cells (PBMC) and in the human monocytic cell lines THP-1 and MonoMac6. We monitored neopterin production and tryptophan degradation in PBMC after treatment with 10 micro m and 100 micro m atorvastatin in the presence or absence of 100 U/ml IFN-gamma, 10 micro g/ml phytohaemagglutinin (PHA) or 10 micro g/ml concanavalin A (ConA) and in monocytic cell lines THP-1 and MonoMac6 with or without stimulation with 100 U/ml IFN-gamma or 10 ng/ml to 1 micro g/ml lipopolysaccharide (LPS). In stimulated PBMC 100 micro m atorvastatin inhibited neopterin formation and tryptophan degradation completely, whereas 10 micro m atorvastatin was only partially effective. Also in monocytic cell lines THP-1 and MonoMac6, atorvastatin was able to suppress IFN-gamma- and LPS-induced formation of neopterin and degradation of tryptophan. Our data from PBMC agree well with previous investigations that statins inhibit T cell activation within the cellular immune response. In addition we demonstrate that atorvastatin directly inhibits IFN-gamma-mediated pathways in monocytic cells, suggesting that both immunoreactivity of T cells and of monocyte-derived macrophages are down-regulated by this statin.

Atorvastatin↗
PubMed2003

Immune activation and degradation of tryptophan in coronary heart disease.

BACKGROUND: Inflammation and immune activation appear to be important in the pathogenesis of coronary heart disease (CHD). Cytokine interferon-gamma, which is released during cell-mediated immune responses, induces indoleamine (2,3)-dioxygenase (IDO), an enzyme degrading tryptophan to kynurenine. Therefore, immune stimulation is commonly associated with an increased kynurenine to tryptophan ratio (kyn trp-1) indicative for activated indoleamine (2,3)-dioxygenase and a measurable decline of tryptophan. METHODS: Blood concentrations of kynurenine and free tryptophan and the kynurenine to tryptophan ratio were examined in 35 patients with coronary heart disease verified by coronary angiography and compared with healthy controls. Patients were observed before percutaneous transluminal coronary angioplasty (21 patients: one with artery disease, nine with 2- or 3-artery disease, and five with restenosis). RESULTS AND CONCLUSIONS: Decreased tryptophan concentrations were found in a significant proportion of coronary heart disease patients and coincided with increased kyn trp-1 and also with increased neopterin concentrations, indicating an activated cellular immune response. We conclude that in coronary heart disease immune activation is associated with an increased rate of tryptophan degradation and thereby lowered tryptophan levels. Results may provide a basis for a better understanding of the pathogenesis of mood disturbances and depression in coronary heart disease patients.

Aged↗
PubMed2003

Interferon-gamma-induced conversion of tryptophan: immunologic and neuropsychiatric aspects.

Tryptophan is an essential amino acid and the least abundant constituent of proteins. In parallel it represents a source for two important biochemical pathways: the generation of neurotransmitter 5-hydroxytryptamine (serotonin) by the tetrahydrobiopterin-dependent tryptophan 5-hydroxylase, and the formation of kynurenine derivatives and nicotinamide adenine dinucleotides initiated by the enzymes tryptophan pyrrolase (tryptophan 2,3-dioxygenase, TDO) and indoleamine 2,3-dioxygenase (IDO). Whereas TDO is located in the liver cells, IDO is expressed in a large variety of cells and is inducible by the cytokine interferon-gamma. Therefore, accelerated tryptophan degradation is observed in diseases and disorders concomitant with cellular immune activation, e. g. infectious, autoimmune, and malignant diseases, as well as during pregnancy. According to the cytostatic and antiproliferative properties of tryptophan-depletion on T lymphocytes, activated T-helper type 1 (Th-1) cells may down-regulate immune response via degradation of tryptophan. Especially in states of persistent immune activation availability of free serum tryptophan is diminished and as a consequence of reduced serotonin production, serotonergic functions may as well be affected. Accumulation of neuroactive kynurenine metabolites such as quinolinic acid may contribute to the development of neurologic/psychiatric disorders. Thus, IDO seems to represent a link between the immunological network and neuroendocrine functions with far reaching consequences in regard to the psychological status of patients. These observations provide a basis for the better understanding of mood disorder and related symptoms in chronic diseases.

Animals↗
PubMed2000

Fiber-optic microsensor for high resolution pCO2 sensing in marine environment.

A fast responding fiber-optic microsensor for sensing pCO2 in marine sediments with high spatial resolution is presented. The tip diameter varies typically between 20 and 50 microm. In order to make the pH-indicator 8-hydroxypyrene-1,3,6-trisulfonate soluble in the ethyl cellulose matrix, it was lipophilized with tetraoctylammonium as the counterion [HPTS-(TOA)4]. The microsensor was tuned to sense very low levels of dissolved carbon dioxide which are typically present in marine systems. The detection limit is 0.04 hPa pCO2 which corresponds to 60 ppb CO2 of dissolved carbon dioxide. A soluble Teflon derivative with an extraordinarily high gas permeability was chosen as a protective coating to eliminate interferences by ionic species like chloride or pH. Response times of less than 1 min were observed. The performance of the new microsensor is described with respect to reproducibility of the calibration curves, dynamic range, temperature behavior, long term stability and storage stability. The effect of hydrogen sulfide as an interferent, which is frequently present in anaerobic sediment layers, was studied in detail.

Journal Article↗