Evaluation of melatonin and AFMK levels in women with breast cancer.

PURPOSE: Changes in the circadian rhythm may contribute to the development of cancer and are correlated with the high risk of breast cancer (BC) in night workers. Melatonin is a hormone synthesized by the pineal gland at night in the absence of light. Levels of melatonin and the metabolite of oxidative metabolism AFMK (acetyl-N-formyl-5-methoxykynurenamine), are suggested as potential biomarkers of BC risk. The aims of this study were to evaluate levels of melatonin and AFMK in women recently diagnosed with BC, women under adjuvant chemotherapy, and night-shift nurses, and compare them with healthy women to evaluate the relation of these compounds with BC risk. METHODS: Blood samples were collected from 47 women with BC, 9 healthy women, 10 healthy night shift nurses, and 6 patients under adjuvant chemotherapy. Compound levels were measured by mass spectrometry. RESULTS AND CONCLUSIONS: Our results showed that women with BC had lower levels of melatonin compared to control group women, and even lower in night-shift nurses and in patients under adjuvant chemotherapy. There was no significant difference of AFMK levels between the groups. In addition to this, high levels of melatonin and AFMK were related to patients with metastasis, and high levels of AFMK were related to the presence of lymph node-positive, tumor > 20 mm and patients who sleep with light at night. Our results showed a reduction of melatonin levels in BC patients, suggesting a relation with the disease, and in addition, point to the importance of melatonin supplementation in women that work at night to reduce the BC risk.

Three serum metabolite signatures for diagnosing low-grade and high-grade bladder cancer.

To address the shortcomings of cystoscopy and urine cytology for detecting and grading bladder cancer (BC), ultrahigh performance liquid chromatography (UHPLC) coupled with Q-TOF mass spectrometry in conjunction with univariate and multivariate statistical analyses was employed as an alternative method for the diagnosis of BC. A series of differential serum metabolites were further identified for low-grade(LG) and high-grade(HG) BC patients, suggesting metabolic dysfunction in malignant proliferation, immune escape, differentiation, apoptosis and invasion of cancer cells in BC patients. In total, three serum metabolites including inosine, acetyl-N-formyl-5-methoxykynurenamine and PS(O-18:0/0:0) were selected by binary logistic regression analysis, and receiver operating characteristic (ROC) test based on their combined use for HG BC showed that the area under the curve (AUC) was 0.961 in the discovery set and 0.950 in the validation set when compared to LG BC. Likewise, this composite biomarker panel can also differentiate LG BC from healthy controls with the AUC of 0.993 and 0.991 in the discovery and validation set, respectively. This finding suggested that this composite serum metabolite signature was a promising and less invasive classifier for probing and grading BC, which deserved to be further investigated in larger samples.

The microbiota and the gut-brain axis: insights from the temporal and spatial mucosal alterations during colonisation of the germfree mouse intestine.

The influence of the gut microbiota on the nervous system, brain development and behaviour, in particular during microbial colonisation of the host, has recently been receiving profound interest. Our time-resolved mining of combined data analyses of the ex-germfree mouse intestine during a 30-day course of colonisation with conventional mouse faecal microbiota (conventionalisation), shed light on temporal altered expression of genes of which the products influenced functions of the nervous system. Plasma tryptophan and kynurenine levels reflected high indoleamine dioxygenase activity, which was supported by significant temporal induction of the encoding gene in all gut tissues. However, the majority of genes associated with neuronal development and function were reduced. Colonic substance P elevation in response to conventionalisation was higher only after 30-days. These results support a functional microbiota-neurohumoral relationship during conventionalisation and suggest a delayed neuronal response that is elicited only after the microbiota accommodating homeostasis has been accomplished.

Altered tryptophan metabolism in FIV-positive cats.

BACKGROUND: Feline immunodeficiency virus (FIV) is analogous to human immunodeficiency virus, the causative agent of human acquired immunodeficiency syndrome (AIDS). In AIDS patients, a progressive reduction in serum tryptophan concentration occurs because of activation of an inducible tryptophan degradation pathway mediated by elevated lamda-interferon production. HYPOTHESIS: Cats infected with FIV have increased tryptophan catabolism evidenced by reduced circulating concentrations of tryptophan and increased concentrations of the tryptophan catabolite kynurenine. ANIMALS: Convenience sample of 235 cats submitted for diagnostic FIV serology (115 FIV-negative and 120 FIV-positive cats). METHODS: Retrospective, cross-sectional study. Serum was assayed for tryptophan and kynurenine using a high performance liquid chromatography assay with fluorescence and ultraviolet detection, respectively. RESULTS: Tryptophan and kynurenine concentrations were log-normally distributed. Geometric mean concentrations were: tryptophan: FIV-positive 30.6 microM (95% CI: 26.8 34.8 microM), FIV-negative 48.9 [microM (95% CI: 43.6-54.9 microM) (P < .001); kynurenine: FIV-positive 22.7 microM (95% CI: 25.5-10.9 microM), FIV-negative 9.9 microM (95% CI: 20.3-9.03 microM) (P < .001). The ratio of kynurenine to tryptophan was: FIV-positive 4.93 (95% CI: 5.62-4.32), FIV-negative 1.34 (95% CI: 1.53 1.17) (P < .0001). CONCLUSIONS AND CLINICAL IMPORTANCE: Serum tryptophan concentration was significantly lower and serum kynurenine concentration was significantly higher in FIV-positive cats. The kynurenine: tryptophan ratio was >3-fold higher in FIV-positive animals, indicating increased tryptophan catabolism in this group. Dietary or pharmacologic intervention to support serum tryptophan concentrations has been shown to be clinically useful in humans with AIDS and might be applicable to cats with FIV infection.

Inhibition of indoleamine 2,3-dioxygenase-mediated tryptophan catabolism accelerates collagen-induced arthritis in mice.

Indoleamine 2,3-dioxygenase (IDO) is one of the initial and rate-limiting enzymes involved in the catabolism of the essential amino acid tryptophan. In cultured cells, the induction of IDO leads to depletion of tryptophan and tryptophan starvation. Recent studies suggest that modulation of tryptophan concentration via IDO plays a fundamental role in innate immune responses. Induction of IDO by interferon-gamma in macrophages and dendritic cells results in tryptophan depletion and suppresses the immune-mediated activation of fibroblasts and T, B, and natural killer cells. To assess the role of IDO in collagen-induced arthritis (CIA), a model of rheumatoid arthritis characterized by a primarily Th1-like immune response, activity of IDO was inhibited by 1-methyl-tryptophan (1-MT) in vivo. The results showed significantly increased incidence and severity of CIA in mice treated with 1-MT. Activity of IDO, as determined by measuring the levels of kynurenine/tryptophan ratio in the sera, was increased in the acute phase of arthritis and was higher in collagen-immunized mice that did not develop arthritis. Treatment with 1-MT resulted in an enhanced cellular and humoral immune response and a more dominant polarization to Th1 in mice with arthritis compared with vehicle-treated arthritic mice. The results demonstrated that development of CIA was associated with increased IDO activity and enhanced tryptophan catabolism in mice. Blocking IDO with 1-MT aggravated the severity of arthritis and enhanced the immune responses. These findings suggest that IDO may play an important and novel role in the negative feedback of CIA and possibly in the pathogenesis of rheumatoid arthritis.

Association of interferon-gamma +874(T/A) single nucleotide polymorphism with the rate of tryptophan catabolism in healthy individuals.

Abstract Mechanisms induced by tryptophan (trp) catabolism are important in the regulation of both normal and pathogenetic immune responses. The key enzyme is indoleamine-pyrrole 2,3-dioxygenase (EC 1.13.11.42) (IDO) which converts trp to kynurenine (kyn), the main toxic metabolite. It is known that interferon-gamma (IFN-gamma) is able to activate IDO. We wanted to analyse whether the strength of this mechanism would be under genetic control. To this end, we analysed the IFN-gamma+874(T/A) genotypes, which are known to have an effect on IFN-gamma production, of 309 healthy blood donors and correlated these to the levels of trp and kyn in their blood. The data obtained demonstrate that the presence of the high producer T allele was associated with increased IDO activity (i.e. elevated kyn and kyn/trp levels), but this effect was observed only in females. These data show that trp catabolism is genetically controlled by the IFN-gamma gene and may thus be operative in those disease conditions associated with the polymorphisms of the IFN-gamma gene.

Synthesis of internal labeled standards of melatonin and its metabolite N1-acetyl-N2-formyl-5-methoxykynuramine for their quantification using an on-line liquid chromatography-electrospray tandem mass spectrometry system.

Melatonin (N-acetyl-5-methoxytryptamine) is implicated in physiologic changes related to light-dark cycles and has been recently found to display antioxidant properties. It is known that the reaction of melatonin with certain reactive oxygen and nitrogen species, such as hydrogen peroxide and singlet oxygen, produces N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK). We report herein on the development of a new liquid chromatography/tandem mass spectrometry (LC/ESI/MS-MS) assay to quantitatively determine melatonin and AFMK. The stable isotopic internal standard of melatonin-D3 was synthesized by the reaction of 5-methoxytryptamine with deuterated acetyl chloride (CD3COCl). Labeled AFMK (AFMK-D3) was obtained after photooxidation of melatonin-D3. The predominant ion [M + H]+ in the full scan mass spectra of melatonin, melatonin-D3, AFMK and AFMK-D3 were located, respectively, at m/z = 233, 236, 265 and 268. The collision-induced dissociation of the molecules revealed a predominant fragment at m/z = 174 for melatonin and melatonin-D3 (loss of the N-acetyl group), and at m/z = 178 for AFMK and AFMK-D3 (loss of both the N-acetyl and the N-formyl groups). The m/z transitions from 233 to 174 (melatonin), from 236 to 174 (melatonin-D3), from 265 to 178 (AFMK), and from 268 to 178 (AFMK-D3) were therefore chosen for the multiple reaction monitoring detection experiments, ensuring a high specificity and an accurate quantification of melatonin and AFMK in human plasma.

Possible relationship between pervasive developmental disorders and platelet monoamine oxidase activity.

1. The present study was undertaken to determine if the platelet monoamine oxidase (MAO) activity of children with childhood-onset Pervasive Developmental Disorders (PDD), atypical PDD and autistic children differs from MAO of normal children of the same age. 2. The kinetic parameters of MAO activity (Km and Vmax for kynuramine as substrate in 100 mM sodium phosphate buffer, pH 7.4 at 37 degrees C) were determined for platelets from autistic (N = 6), childhood onset PDD (N = 6) and atypical PDD (N = 6) children and 14 controls aged 6-10 years. 3. PDD children had significantly lower Km (4.41 +/- 0.26 vs 5.30 +/- 0.23 microM) and Vmax (16.77 +/- 1.56 vs 22.15 +/- 2.16 nmol h-1 mg protein-1) than control children. The reduction in Vmax was demonstrable in MAO activity measured with 100 microM substrate (14.93 +/- 1.13 vs 20.96 +/- 2.10 nmol h-1 mg-1). 4. These data show that childhood-onset PDD patients, in which the syndrome was complete, presented the lowest levels of platelet MAO activity.

A new metabolic pathway for N,N-dimethyltryptamine.

N,N-Dimethyltryptamine (DMT) undergoes a major structural alteration when added to whole human blood or its red blood cells in vitro. A new high-pressure liquid chromatography (HPLC) peak is present in extracts of these treated tissues. The compound responsible for this peak has been identified by ultraviolet spectrophotometry and by mass spectrometry as dimethylkynuramine (DMK). The enzyme responsible for this appears to be different from tryptophan 2,3-dioxygenase and also from indoleamine 2,3-dioxygenase.