The process of induction of tryptophan oxygenase in Pseudomonas acidovorans is typical of many microbial enzyme induction systems, in that it (i) requires cell multiplication and de novo protein synthesis, (ii) is subject to catabolite repression, (iii) results in the formation of a stable enzyme, whose level, upon removal of inducer, is diluted out by cell proliferation, and (iv) exhibits prod...

AIMS We have previously suggested that acute ethanol consumption by normal subjects decreases the availability of circulating tryptophan (Trp) to the brain by activating liver Trp pyrrolase, the first and rate-limiting enzyme of the (major) kynurenine pathway of Trp degradation. The aim of the present study was to examine this hypothesis further by measuring plasma levels of kynurenine metaboli...

Liver tryptophan pyrrolase and kynureninase activity decreased when rats were fed the hepatic carcinogen 3'-methyl-4-dimethylaminoazobenzene, whereas li ver kynurenine transaminase activity did not differ significantly from that of the controls. Liver tumors induced by this aminoazo dye had very low kynurenine transaminase activity and no detectable tryptophan pyrrolase or kynureninase activity...

T-cell dysfunction after human hematopoietic stem-cell transplantation (HSCT) is generally attributed to intrinsic T-cell defects. Here we show that the characteristic impaired proliferative responses to polyclonal stimulation of post-HSCT peripheral blood mononuclear cells (PB-MCs) were markedly (4-fold) improved by T-cell enrichment. Conversely, addback of post-HSCT monocytes to these enriche...

OBJECTIVE Obesity is associated with increased inflammation and insulin resistance. In conditions with chronic immune activation, low plasma vitamin B6-levels are described, as well as an increased kynurenine:tryptophan-ratio (KTR). We investigated circulating tryptophan, kynurenine and its metabolites, neopterin, B-vitamins, CRP, and HbA1c in individuals with obesity before and after bariatric...

In chronic granulomatous disease (CGD), defective phagocytic nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity causes reduced superoxide anion (O(2)(·)) radical production leading to frequent infections as well as granulomas and impaired wound healing indicative of excessive inflammation. Based on recent mouse studies, the lack of O(2)(·)-dependent interferon γ (IFNγ)-induced...

The enzyme reactions bringing about oxidation in the indole ring of tryptophan and kynurenine formation furnish a convenient example of those poorly understood systems producing aromatic ring oxidations. The metabolism of tryptophan via kynurenine has been studied in different instances by nutritional, isotopic, genetic, and adaptive experiments; thus this metabolic pathway has been well docume...

1. Nicotinylalanine, an inhibitor of kynurenine metabolism, has been shown to elevate brain levels of endogenous kynurenic acid, an excitatory amino acid receptor antagonist. This study examined the potential of nicotinylalanine to influence excitotoxic damage to striatal NADPH diaphorase (NADPH-d) and gamma-aminobutyric acid (GABA)ergic neurones that are selectively lost in Huntington's diseas...

Psychosocial stress is a major risk factor for mood and anxiety disorders, in which excessive reactivity to aversive events/stimuli is a major psychopathology. In terms of pathophysiology, immune-inflammation is an important candidate, including high blood and brain levels of metabolites belonging to the kynurenine pathway. Animal models are needed to study causality between psychosocial stress...

BACKGROUND AND PURPOSE Depression is a commonly occurring and persistent sequel of stroke affecting approximately 29% of patients. An immunological hypothesis has been put forward, and synthesis of kynurenine from tryptophan has been proposed to link inflammatory activity with neurotoxicity and neurotransmitter dysfunction. This study assessed the relationship between peripheral blood kynurenin...