Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0406810 (NAME)
 13,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent studies indicate that sepsis is associated with enhanced generation of several free radical species (nitric oxide, superoxide, hydrogen peroxide) in skeletal muscle. While studies suggest that free radical generation causes uncoupling of oxidative phosphorylation in sepsis, no previous report has examined the role of free radicals in modulating skeletal muscle oxygen consumption during State 3 respiration or inhibiting the electron transport chain in sepsis. The purpose of the present study was to examine the effects of endotoxin-induced sepsis on State 3 diaphragm mitochondrial oxygen utilization and to determine if inhibitors/scavengers of various free radical species would protect against these effects. We also examined mitochondrial protein electrophoretic patterns to determine if observed endotoxin-related physiological derangements were accompanied by overt alterations in protein composition. Studies were performed on: (a) control animals, (b) endotoxin-treated animals, (c) animals given endotoxin plus PEG-SOD, a superoxide scavenger, (d) animals given endotoxin plus L-NAME, a nitric oxide synthase inhibitor, (e) animals given only PEG-SOD or L-NAME, (f) animals given endotoxin plus D-NAME, and (g) animals given endotoxin plus denatured PEG-SOD. We found: (a) no alteration in maximal State 3 mitochondrial oxygen consumption rate at 24 h after endotoxin administration, but (b) a significant reduction in oxygen consumption rate at 48 h after endotoxin, (c) no effect of endotoxin to induce uncoupling of oxidative phosphorylation, (d) either PEG-SOD or L-NAME (but neither denatured PEG-SOD nor D-NAME) prevented endotoxin-mediated reductions in State 3 respiration rates, (e) some mitochondrial proteins underwent tyrosine nitrosylation at 24 h after endotoxin administration, and (f) SDS-page electrophoresis of mitochondria from endotoxin-treated animals revealed a selective depletion of several proteins at 48 h after endotoxin administration (but not at 24 h); (g) administration of L-NAME or PEG-SOD prevented this protein depletion. These data provide the first evidence that endotoxin-induced reductions in State 3 mitochondrial oxygen consumption are free radical-mediated.
 ...
PMID:Free radicals alter maximal diaphragmatic mitochondrial oxygen consumption in endotoxin-induced sepsis. 1113 3

Recent studies have indicated that sepsis is associated with enhanced generation of several free-radical species (nitric oxide [NO], superoxide, hydrogen peroxide) in skeletal muscle. It is also known that this enhanced free-radical generation results in reductions in skeletal muscle force-generating capacity, but the precise mechanism(s) by which free radicals exert this effect in sepsis has not been determined. We postulated that free radicals might react directly with the contractile proteins in this condition, altering contractile protein force-generating capacity. To test this theory, we compared the force generation of single Triton-skinned diaphragmatic fibers (Triton skinning exposes the contractile apparatus, permitting direct assessment of contractile protein function) from the following groups of rats: (1) control animals; (2) endotoxin-treated animal; (3) animals given endotoxin plus polyethylene glycol- superoxide dismutase (PEG-SOD), a superoxide scavenger; (4) animals given endotoxin plus N(omega)-nitro-L-arginine methylester (L-NAME), a NO synthase inhibitor; (5 ) animals given only PEG-SOD or L-NAME; and (6 ) animals given endotoxin plus denatured PEG-SOD. We found that endotoxin administration produced both a reduction in the maximum force-generating capacity (Fmax) (i.e., a decrease in Fmax) of muscle fibers and a reduction in fiber calcium sensitivity (i.e., an increase in the Ca2+ concentration required to produce half-maximal activation [Ca50]). L-NAME and PEG-SOD administration preserved Fmax and Ca50 in endotoxin-treated animals; neither drug affected these parameters in non-endotoxin treated animals. Denatured PEG-SOD failed to inhibit endotoxin-related alterations in contractile protein function. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of skinned fibers from endotoxin-treated animals revealed a selective depletion of several proteins; administration of L-NAME or PEG-SOD to endotoxin-treated animals prevented this protein depletion, paralleling the effect of these two agents to prevent a reduction in contractile protein force-generating capacity. These data indicate that free radicals (superoxide, NO, or daughter species of these radicals) play a central role in altering skeletal muscle contractile protein force-generating capacity in endotoxin-induced sepsis.
 ...
PMID:Free radical-induced contractile protein dysfunction in endotoxin-induced sepsis. 1115 56

We hypothesized that transient high-glucose concentration interferes with mediation by nitric oxide (NO) of flow-induced dilation (FID) of arterioles due to enhanced production of superoxide. In isolated, pressurized (80 mmHg) rat gracilis muscle arterioles ( approximately 130 microm) after transient high-glucose treatment (tHG; incubation with 30 mM glucose for 1 h), FID was reduced (maximum: control, 38 +/- 4%; after tHG, 17 +/- 3%), which was not further diminished by the NO synthase (NOS) inhibitor N(omega)-nitro-l-arginine methyl ester (l-NAME; 18 +/- 2%). Correspondingly, an enhanced polyethylene-glycol-SOD (PEG-SOD)-sensitive superoxide production was detected after tHG in carotid arteries by dihydroethydine (DHE) staining. Presence of PEG-SOD during tHG prevented the reduction of FID (41 +/- 3%), which could be inhibited by l-NAME (20 +/- 4%). Administration of PEG-SOD after tHG did not prevent the reduction of FID (22 +/- 3%). Sepiapterin, a precursor of the NO synthase cofactor tetrahydrobiopterin (BH(4)), administered during tHG did not prevent the reduction of FID (maximum, 15 +/- 5%); however, it restored FID when administered after tHG (32 +/- 4%). Furthermore, inhibition of either glycolysis by 2-deoxyglucose or mitochondrial complex II by 2-thenoyltrifluoroacetone reduced the tHG-induced DHE-detectable enhanced superoxide production in carotid arteries and prevented FID reduction in arterioles (39 +/- 5 and 35 +/- 2%). Collectively, these findings suggest that in skeletal muscle arterioles, a transient elevation of glucose via its increased metabolism, elicits enhanced production of superoxide, which decreases the bioavailability of NO and the level of the NOS cofactor BH(4), resulting in a reduction of FID mediated by NO.
 ...
PMID:Microvascular dysfunction after transient high glucose is caused by superoxide-dependent reduction in the bioavailability of NO and BH(4). 1504 90

Identification and quantification of specific reactive oxygen species (ROS) is essential to allow greater understanding into the role that ROS play in tissues and extracellular fluids. Previous studies have examined the reduction of cytochrome c and the hydroxylation of salicylate to detect superoxide and hydroxyl activity, respectively, although the specificity of these assays has been the subject of debate. This study aimed to identify the factors influencing hydroxylation of salicylate and reduction of cytochrome c in microdialysates from skeletal muscle extracellular fluid. Mice were anesthetized and treated with either polyethylene glycol-tagged superoxide dismutase (PEG-SOD), desferrioxamine mesylate (desferal) or N(G)-nitro-l-arginine methyl ester (l-NAME). A further cohort of untreated mice was also studied. Microdialysis probes were placed into the gastrocnemius muscle and perfused with salicylate or cytochrome c prior to, during, and after a period of demanding electrically stimulated contractions. Microdialysates were analysed for the reduction of cytochrome c and hydroxylation of salicylate. Contractile activity was found to increase both the reduction of cytochrome c and the hydroxylation of salicylate in the microdialysates. The reduction of cytochrome c was greater in mice treated with l-NAME compared with control untreated mice and was attenuated in mice treated with PEG-SOD. The hydroxylation of salicylate was attenuated in mice treated with desferal while there was no effect of l-NAME compared with untreated mice. Data support the hypothesis that superoxide and hydroxyl radical activity are the major contributors to the reduction of cytochrome c and hydroxylation of salicylate respectively in microdialysates from skeletal muscle extracellular fluid and indicate that these ROS are increased by contractile activity in skeletal muscle extracellular fluid.
 ...
PMID:Microdialysis studies of extracellular reactive oxygen species in skeletal muscle: factors influencing the reduction of cytochrome c and hydroxylation of salicylate. 1627 81

1. This study investigates the role of nitric oxide (NO) and reactive oxygen species (ROS) on endothelial function of pulmonary arteries in a mice model of hypoxia-induced pulmonary hypertension. 2. In pulmonary arteries from control mice, the NO-synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME) potentiated contraction to prostaglandin F2alpha (PGF2alpha) and completely abolished relaxation to acetylcholine. In extrapulmonary but not intrapulmonary arteries, acetylcholine-induced relaxation was slightly inhibited by polyethyleneglycol-superoxide dismutase (PEG-SOD) or catalase. 3. In pulmonary arteries from hypoxic mice, ROS levels (evaluated using dihydroethidium staining) were higher than in controls. In these arteries, relaxation to acetylcholine (but not to sodium nitroprusside) was markedly diminished. L-NAME abolished relaxation to acetylcholine, but failed to potentiate PGF2-induced contraction. PEG-SOD or catalase blunted residual relaxation to acetylcholine in extrapulmonary arteries, but did not modify it in intrapulmonary arteries. Hydrogen peroxide elicited comparable (L-NAME-insensitive) relaxations in extra- and intrapulmonary arteries from hypoxic mice. 4. Exposure of gp91phox(-/-) mice to chronic hypoxia also decreased the relaxant effect of acetylcholine in extrapulmonary arteries. However, in intrapulmonary arteries from hypoxic gp91phox(-/-) mice, the effect of acetylcholine was similar to that obtained in mice not exposed to hypoxia. 5. Chronic hypoxia increases ROS levels and impairs endothelial NO-dependent relaxation in mice pulmonary arteries. Mechanisms underlying hypoxia-induced endothelial dysfunction differ along pulmonary arterial bed. In extrapulmonary arteries from hypoxic mice, endothelium-dependent relaxation appears to be mediated by ROS, in a gp91phox-independent manner. In intrapulmonary arteries, endothelial dysfunction depends on gp91phox, the latter being rather the trigger than the mediator of impaired endothelial NO-dependent relaxation
 ...
PMID:Role of reactive oxygen species and gp91phox in endothelial dysfunction of pulmonary arteries induced by chronic hypoxia. 1671 16

Sepsis-induced acute lung injury (ALI) is characterized by injury of the pulmonary microvascular endothelial cells (PMVEC) leading to high-protein pulmonary edema. Inducible NO synthase (iNOS) mediates trans-PMVEC protein leak in septic mice in vivo and in murine PMVEC under septic conditions in vitro, but the role of iNOS in human PMVEC protein leak has not been addressed. We hypothesized that iNOS in human neutrophils, but not human PMVEC, mediates septic trans-PMVEC protein leak in vitro. We isolated human PMVEC from lung tissue using magnetic bead-bound anti-PECAM antibody and assessed Evans blue albumin leak across human PMVEC monolayers under septic conditions in the presence/absence of human neutrophils. PMVEC were used at passages 3-4, seeded on 3 mum Transwell inserts and grown to confluence. Cytomix-stimulated trans-PMVEC albumin leak was not attenuated by pre-treatment with 1400 W, a selective iNOS inhibitor, or l-NAME, a non-selective NOS inhibitor. In neutrophil-PMVEC co-culture, basal unstimulated trans-EB-albumin leak was 0.6+/-0.3%, which was increased by cytomix stimulation to 11.5+/-4.4%, p<0.01. Cytomix-stimulated EB-albumin leak in neutrophil-PMVEC co-cultures was inhibited by pre-treatment with 1400 W (3.8+/-1.0%, p<0.05) or l-NAME (4.0+/-1.1%, p<0.05). Pre-treatment of neutrophil-PMVEC co-cultures with PEG-SOD (superoxide scavenger) and FeTPPS (peroxynitrite scavenger) also significantly attenuated neutrophil-dependent cytomix-stimulated leak (4.7+/-3.0%, p<0.05; 0.5+/-1.0%, p<0.01, respectively). In conclusion, trans-human PMVEC albumin leak under septic conditions is dependent on iNOS activity specifically in neutrophils, but not in PMVEC themselves. Septic neutrophil-dependent trans-PMVEC albumin leak may be mediated by peroxynitrite.
 ...
PMID:Inducible NO synthase (iNOS) in human neutrophils but not pulmonary microvascular endothelial cells (PMVEC) mediates septic protein leak in vitro. 1745 52

Activation of the NO/cGMP pathway modulates smooth muscle cells relaxation and hence vasoconstriction, a major hindrance for the use of cell-free haemoglobin (Hb) as blood substitute, despite conjugation with 5-kDa maleimide poly(ethylene)-glycol (PEG) reduces vasoconstriction in vivo. We aimed at assessing how a recently developed PEGylated-Hb (Deoxy-PEGHb) and manipulation of the NO/cGMP pathway enable modulation of vasoconstriction in isolated rat hearts. Hearts were Langendorff-perfused with oxygenated Krebs-Henseleit (15 ml/min) while monitoring the coronary pressure (CPP) after injection (1 min) of 50 nM norepinephrine followed by a 1 microM Hb or Deoxy-PEGHb bolus, without altering the flow. Deoxy-PEGHb induced less vasoconstriction than Hb. Although the presence of PEG could contribute to vasoconstriction, Deoxy-PEGHb did not contain appreciable amounts of free PEG. Whereas reducing endothelial NO release by 0.2 mM L-NAME increased vasoconstriction, abolishing NO scavenging by Hb using its cyanomet derivative almost completely blunted it. Furthermore, maintaining intracellular cyclic GMP by inhibiting phosphodiesterase-5 with 0.02 mM sildenafil enabled control of Hb-induced vasoconstriction. We conclude that, although PEG-Hb represents a possible approach to limit Hb-induced vasoconstriction, manipulating the NO/cGMP pathway may provide a powerful way to circumvent this problem.
 ...
PMID:Modulation of the NO/cGMP pathway reduces the vasoconstriction induced by acellular and PEGylated haemoglobin. 1824 81

Inducible nitric oxide (NO) synthase (iNOS) from neutrophils and alveolar macrophages (AM) contributes to the pathophysiology of murine septic acute lung injury (ALI). It is not known if AM iNOS has a direct effect on septic pulmonary microvascular endothelial cell (PMVEC) permeability. We hypothesized that AM iNOS mediates PMVEC permeability in vitro under septic conditions through NO and peroxynitrite. 100,000 confluent PMVEC on cell-culture inserts were co-incubated with iNOS+/+ vs. iNOS-/- AM, in various ratios of AM to PMVEC. PMVEC injury was assessed by trans-PMVEC Evans Blue-labelled albumin flux in the presence or absence of cytomix (equimolar TNF-alpha, IL-1beta and IFN-gamma). Cytomix stimulation dose-dependently increased trans-PMVEC EB-albumin flux, which was exaggerated (1.4+/-0.1% vs. 0.4+/-0.1% in unstimulated PMVEC, p<0.05) in the presence of iNOS+/+, but not iNOS-/-, AM in the upper compartment. Similarly, iNOS+/+, but not iNOS-/-, AM in the lower compartment also enhanced septic trans-PMVEC albumin leak. The mechanism of iNOS-dependent septic PMVEC permeability was pursued through pharmacologic studies with inhibitors of NOS, and scavengers of NO, superoxide, and peroxynitrite, and treatment of PMVEC with the NO donor, DETA-NONOate. Septic iNOS+/+ AM-dependent trans-PMVEC albumin leak was significantly attenuated by pharmacologic iNOS inhibition (L-NAME and 1400W), and scavenging of either NO (oxyhemoglobin), superoxide (PEG-SOD), or peroxynitrite (FeTPPS). Exogenous NO (DETA-NONOate) had no effect on PMVEC permeability. These data are consistent with a direct role of AM iNOS in septic PMVEC barrier dysfunction, which is likely mediated, in part, through peroxynitrite.
 ...
PMID:Alveolar macrophage inducible nitric oxide synthase-dependent pulmonary microvascular endothelial cell septic barrier dysfunction. 1870 74

A new polyethylene glycol fiber was developed for solid-phase microextraction (SPME) of styrene by electrodepositing porous Zn film on Ag wire substrate followed by coating with polyethylene glycol sol-gel (Ag/Zn/PEG sol-gel fiber). The scanning electron micrographs of fibers surface revealed a highly porous structure. The extraction property of the developed fiber-to-styrene residue from polystyrene packaged food was investigated by headspace solid-phase microextraction (HS-SPME) and analyzed with a gas chromatograph coupled with flame ionization detection (GC-FID). The new Ag/Zn/PEG sol-gel fiber is simple to prepare, low cost, robust, has high thermal stability and long lifetime, up to 359 extractions. Repeatability of one fiber (n=6) was in the range of 4.7-7.5% and fiber-to-fiber reproducibility (n=4) for five concentration values were in the range 3.4-10%. This Ag/Zn/PEG sol-gel fiber was compared to two commercial SPME fibers, 75 microm carboxen/polydimethylsiloxane (CAR/PDMS) and 100 microm polydimethylsiloxane (PDMS). Under their optimum conditions, Ag/Zn/PEG sol-gel fiber showed the highest sensitivity and the lowest detection limit at 0.28+/-0.01 ng mL(-1).
 ...
PMID:A new polyethylene glycol fiber prepared by coating porous zinc electrodeposited onto silver for solid-phase microextraction of styrene. 2022 31

In numerous vascular beds, acetylcholine (ACh) evokes the simultaneous release of endothelium-derived relaxing and contracting factors (EDRF and EDCF, respectively). We aimed to determine whether ACh evokes the release of an EDCF in the chicken ductus arteriosus (DA) and to identify its nature. Isolated rings DA from 19-d chicken embryos (total incubation: 21-d) were studied in a wire myograph. Low concentrations of ACh (30 nM-1 microM) elicited a relaxation, which was followed by a contraction at higher concentrations (3 microM-0.1 mM). Both relaxation and contraction were abolished by removal of endothelium and were sensitive to the antimuscarinic agents atropine and 4-DAMP (M3-receptor antagonist). ACh-induced contraction was impaired in the presence of the non-selective inhibitor of cyclooxygenase (COX) indomethacin, the selective COX-1 inhibitor valeryl salicylate, and the thromboxane (TX)/prostaglandin (PG) H2 (TP) receptor blocker SQ-29458, whereas the response was not affected by the selective COX-2 inhibitor nimesulide, the TX synthase inhibitor furegrelate, the H2O2 scavenger PEG-catalase, the nitric oxide synthase inhibitor L-NAME, or the soluble guanylate cyclase inhibitor ODQ. Enzyme immunoassay determined that, under basal conditions, the chicken DA produced PGE2, PGF2alpha and TXB2 (stable metabolite of TXA2). Prostanoid production was inhibited by indomethacin but was not significantly affected by ACh. We conclude that in the chicken DA, stimulation of muscarinic receptors by ACh induces an endothelium-dependent relaxation followed by an endothelium-dependent contraction. The contraction involves COX-1 activation and TP receptor stimulation.
 ...
PMID:Endothelium-dependent contraction induced by acetylcholine in the chicken ductus arteriosus involves cyclooxygenase-1 activation and TP receptor stimulation. 2048 53


1 2 3 Next >>