Search results for "Pterin"
showing 10 items of 75 documents
Arginine and nitric oxide synthase: regulatory mechanisms and cardiovascular aspects
2014
L-Arginine (L-Arg) is a conditionally essential amino acid in the human diet. The most common dietary sources of L-Arg are meat, poultry and fish. L-Arg is the precursor for the synthesis of nitric oxide (NO); a key signaling molecule via NO synthase (NOS). Endogenous NOS inhibitors such as asymmetric-dimethyl-L-Arg inhibit NO synthesis in vivo by competing with L-Arg at the active site of NOS. In addition, NOS possesses the ability to be "uncoupled" to produce superoxide anion instead of NO. Reduced NO bioavailability may play an essential role in cardiovascular pathologies and metabolic diseases. L-Arg deficiency syndromes in humans involve endothelial inflammation and immune dysfunctions…
Cardiovascular and Endocrine Properties of L-Tryptophan in Combination with Various Diets
1991
Brain serotonin neurons are intimately involved in a number of relevant physiological functions such as cardiovascular regulation, neuroendocrine output from the anterior pituitary (e.g. ACTH, prolactin), regulation of behavior (e.g. agression, sleep, locomotor and sexual behavior), mood or appetite control (Fernstrom, 1983; Lehnert et al., 1987; Spring et al., 1987; Wurtman, 1987). The synthesis of brain serotonin is dependent on the availability of the large neutral amino acid L-tryptophan that is hydroxylated to 5-L-hydroxytryptophan and subsequently decarboxylated to yield serotonin. The rate-limiting enzyme tryptophan hydroxylase has a Michaelis constant of approximately 2–3 x 10−5 M w…
Neopterin, cellular adhesion molecules and myeolperoxidase in patients with stable and unstable angina pectoris
2011
Neopterin, cellular adhesion molecules and myeolperoxidase in patients with stable and unstable angina pectoris Recent data indicate that the serum level of neopterin, a marker of inflammation and immune modulator secreted by monocytes/macrophages, is elevated in patients with acute coronary syndrome (ACS) and seems to be a prognostic marker for major cardiovascular events. Soluble cellular adhesion molecules (sCAMs) and myeloperoxidase (MPO) levels are also related to ACS. The aim of the present study was to evaluate differences in serum levels of neopterin, sCAMs and MPO between coronary artery disease and metabolic syndrome (CAD-MetS) patients with stable and unstable angina pectoris (SA…
Immunomodulatory and Hematopoietic Effects of Recombinant Human Interleukin-6 in Patients with Advanced Renal Cell Cancer
1996
Interleukin-6 (IL-6) is a cytokine with pleiotropic biologic activities on B cells, T cells, and hematopoietic progenitors. The present study was undertaken to assess pharmacodynamic effects of subcutaneous administration of IL-6 on blood counts, immunologic parameters, and acute-phase reactants. Blood samples were taken from patients with advanced renal cell cancer participating in a phase II trial of recombinant human IL-6. Multiparameter FACS analyses of peripheral blood mononuclear cells were performed using antibodies against CD3, CD4, CD8, HLA-DR, CD56, CD28, CD38, CD19, sIgM, and sIgG. Serum levels of IL-10, soluble CD23 (sCD23), sCD25, IL-1 receptor antagonist protein (IL-1RA), solu…
Nitric Oxide Synthesis in Vascular Physiology and Pathophysiology
2015
Nitric oxide (NO) is produced by three NO synthase (NOS) isoforms: neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS). Under physiological conditions, vascular NO is produced by eNOS and nNOS, with both playing atheroprotective roles. Under pathological conditions, iNOS can be induced and eNOS may become uncoupled. iNOS produces a large amount of NO, induces vascular dysfunction, and promotes atherogenesis. Uncoupled eNOS generates superoxide instead of NO and contributes significantly to endothelial dysfunction and atherogenesis. Major mechanisms of eNOS uncoupling include depletion of tetrahydrobiopterin, an essential co-factor for the eNOS enzyme, and deficiency of L-a…
Nitric oxide synthases: regulation and function
2011
Nitric oxide (NO), the smallest signalling molecule known, is produced by three isoforms of NO synthase (NOS; EC 1.14.13.39). They all utilize l-arginine and molecular oxygen as substrates and require the cofactors reduced nicotinamide-adenine-dinucleotide phosphate (NADPH), flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), and (6R-)5,6,7,8-tetrahydrobiopterin (BH(4)). All NOS bind calmodulin and contain haem. Neuronal NOS (nNOS, NOS I) is constitutively expressed in central and peripheral neurons and some other cell types. Its functions include synaptic plasticity in the central nervous system (CNS), central regulation of blood pressure, smooth muscle relaxation, and vasodila…
eNOS Uncoupling in Cardiovascular Diseases - the Role of Oxidative Stress and Inflammation
2013
Many cardiovascular diseases and drug-induced complications are associated with - or even based on - an imbalance between the formation of reactive oxygen and nitrogen species (RONS) and antioxidant enzymes catalyzing the break-down of these harmful oxidants. According to the “kindling radical” hypothesis, the formation of RONS may trigger in certain conditions the activation of additional sources of RONS. According to recent reports, vascular dysfunction in general and cardiovascular complications such as hypertension, atherosclerosis and coronary artery diseases may be connected to inflammatory processes. The present review is focusing on the uncoupling of endothelial nitric oxide synthas…
Biopterin metabolism and eNOS expression during hypoxic pulmonary hypertension in mice.
2013
International audience; Tetrahydrobiopterin (BH$_4$), which fosters the formation of and stabilizes endothelial NO synthase (eNOS) as an active dimer, tightly regulates eNOS coupling / uncoupling. Moreover, studies conducted in genetically-modified models demonstrate that BH$_4$ pulmonary deficiency is a key determinant in the pathogenesis of pulmonary hypertension. The present study thus investigates biopterin metabolism and eNOS expression, as well as the effect of sepiapterin (a precursor of BH$_4$) and eNOS gene deletion, in a mice model of hypoxic pulmonary hypertension. In lungs, chronic hypoxia increased BH$_4$ levels and eNOS expression, without modifying dihydrobiopterin (BH$_2$, t…
Prevention of Atherosclerosis by Interference with the Vascular Nitric Oxide System
2009
Nitric oxide (NO) produced by endothelial NO synthase (eNOS) represents an anti-atherosclerotic principle. NO bioavailability is decreased in atherosclerosis due to increased NO inactivation by reactive oxygen species and reduced NO synthesis. Various types of vascular pathophysiology are associated with oxidative stress, with NADPH oxidases as the major source of reactive oxygen species. These inactivate NO. Also, oxidative stress is likely to be the main cause for oxidation of the essential NOS cofactor, tetrahydrobiopterin (BH(4)). A lack of BH(4) leads to eNOS uncoupling (i.e., uncoupling of oxygen reduction from NO synthesis in eNOS). Based on these pathomechanisms, the therapeutic pot…
Influence of cold ischemia time on complement activation, neopterin, and cytokine release in liver transplantation.
2004
The aim of this study was to determine whether a cold ischemia time (CIT) of12 hours influences the activation of complement as well as the plasma concentrations of neopterin, interleukin (IL)-6, or IL-8 in orthotopic liver transplantation (OLT).Eighteen consecutive patients undergoing OLT using a veno-venous bypass technique were divided into 2 groups: duration of CIT12 hours (group 1; n = 11), and CIT12 hours (group 2; n = 7). Blood samples were drawn preoperatively, 1 minute before, and 120 minutes after reperfusion.Preoperatively, complement split products, neopterin, IL-6, and IL-8 levels did not differ between the groups. At 120 minutes after reperfusion, the concentrations of C3a, SC…