Clinical significance of plasma-free amino acids and tryptophan metabolites in patients with non-small cell lung cancer receiving PD-1 inhibitor: a pilot cohort study for developing a prognostic multivariate model.

BACKGROUND: Amino acid metabolism is essential for tumor cell proliferation and regulation of immune cell function. However, the clinical significance of free amino acids (plasma-free amino acids (PFAAs)) and tryptophan-related metabolites in plasma has not been fully understood in patients with non-small cell lung cancer (NSCLC) who receive immune checkpoint inhibitors. METHODS: We conducted a single cohort observational study. Peripheral blood samples were collected from 53 patients with NSCLC before treatment with PD-1 (Programmed cell death-1) inhibitors. The plasma concentrations of 21 PFAAs, 14 metabolites, and neopterin were measured by liquid chromatography-mass spectrometry. Using Cox hazard analysis with these variables, a multivariate model was established to stratify patient overall survival (OS). Gene expression in peripheral blood mononuclear cells (PBMCs) was compared between the high-risk and low-risk patients by this multivariate model. RESULTS: On Cox proportional hazard analysis, higher concentrations of seven PFAAs (glycine, histidine, threonine, alanine, citrulline, arginine, and tryptophan) as well as lower concentrations of three metabolites (3h-kynurenine, anthranilic acid, and quinolinic acid) and neopterin in plasma were significantly correlated with better OS (p<0.05). In particular, the multivariate model, composed of a combination of serine, glycine, arginine, and quinolinic acid, could most efficiently stratify patient OS (concordance index=0.775, HR=3.23, 95% CI 2.04 to 5.26). From the transcriptome analysis in PBMCs, this multivariate model was significantly correlated with the gene signatures related to immune responses, such as CD8 T-cell activation/proliferation and proinflammatory immune responses, and 12 amino acid-related genes were differentially expressed between the high-risk and low-risk groups. CONCLUSIONS: The multivariate model with PFAAs and metabolites in plasma might be useful for stratifying patients who will benefit from PD-1 inhibitors.

Ischemic Stroke and Kynurenines: Medicinal Chemistry Aspects.

Ischemic stroke is one of the leading causes of mortality and permanent disability in developed countries. Stroke induces massive glutamate release, which in turn causes N-Methyl-D-aspartate (NMDA) receptor over-excitation and thus, calcium overload in neurons leading to cell death via apoptotic cascades. The kynurenine pathway is a complex enzymatic cascade of tryptophan catabolism, generating various neuroactive metabolites. One metabolite, kynurenic acid (KYNA), is a potent endogenous NMDA glutamate receptor antagonist, making it a possible therapeutic tool to decrease excitotoxicity and neuroinflammation. Recently, clinical investigations have shown that during the acute phase of ischemic stroke, kynurenine pathway is activated and peripheral levels of metabolites correlated with worse outcome. In this review, we set out to summarize the current literature on the connection of the kynurenine pathway and ischemic stroke and set a course for future investigations and potential drug development.

Actividad In vitro de norfloxacina en 183 patogenos urinarios / In vitro activity of norfoxacin in 183 urinary pathogens

Determinacion y comparacion de la actividad in vitro de la norfloxacina con otros antimicrobianos en bacterias obtenidas de urocultivos

[Changes in the activity of an epileptogenic focus in the hippocampus of rats treated with the chief metabolites of tryptophan]. / Izmenenie aktivnosti épileptogennogo ochaga v gippokampe krys pod vliianiem osnovnykh metabolitov triptofana.

It has been shown in rats, as previously on frogs, with electrochemotrodes chronically implanted into dorsal hippocampuses that some kynurenine metabolites of tryptophan (quinolinic acid, d, 1-kynurenine) can provoke an increase in the pathological activity of the penicillin-induced epileptogenic focus in the hippocampus. Unlike kynurenines, serotonin, another tryptophan metabolite, and the serotoninomimetic 5-methoxytryptamine suppress the pathological activity of the epileptogenic focus. The results obtained support the hypothesis about a certain role of kynurenines and serotonin in the pathogenesis of epilepsy.

Inhibition of renal gluconeogenesis by guinolinate and hydrazine in diabetic rats.

Renal as well as hepatic gluconeogenesis is inappropriately accelerated in the diabetic state when plasma glucose levels are elevated. Known regulatory mechanisms influence gluconeogenesis in both organs. However, under certain circumstances gluconeogenesis may be affected in one organ and not the other. Recent studies with the tryptophan metabolite, quinolinate, suggest that hepatic gluconeogenesis in the diabetic is unaffected by this agent, whereas gluconeogenesis is blocked in the normal liver. These experiments have been interpreted as providing evidence for the lack of a specific physiologic repressor for gluconeogenesis in diabetic liver. In the present study quinolinate and hydrazine are shown to be effective inhibitors of the accelerated gluconeogenesis in the renal cortex of diabetic rats. Thus, the renal gluconeogenic mechanism in diabetics retains the capacity to recognize quinolinate as an inhibitor, but may be influenced by the depressed conversion of tryptophan to quinolinate in the intact diabetic organism.