scholarly journals In Vivo Bypass Efficiencies and Mutational Signatures of the Guanine Oxidation Products 2-Aminoimidazolone and 5-Guanidino-4-nitroimidazole

2004 ◽  
Vol 279 (42) ◽  
pp. 43568-43573 ◽  
Author(s):  
William L. Neeley ◽  
James C. Delaney ◽  
Paul T. Henderson ◽  
John M. Essigmann
2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Andrea Iorga ◽  
Gabriel Wong ◽  
Denise Mai ◽  
Jingyuan Li ◽  
Salil Sharma ◽  
...  

Pulmonary hypertension (PH) is a chronic lung disease characterized by progressively elevated pulmonary arterial pressures and severe pulmonary vascular remodeling resulting from interactions between oxidized lipoprotein deposition and increased endothelial proliferation. Previously we have shown increased plasma levels of biological oxidation products such as hydroxyoctadecadienoic acids (HODEs) and hydroxyeicosatetraenoic acids (HETEs) in the rat monocrotaline model of PH. Here we investigated the role of HETEs and HODEs in the development of PH and whether their inhibition with the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) attenuates the progression of PH. Mice were placed in a hypoxic chamber with O2 concentrations of ≤10% for 21 days and either left untreated to develop PH (n=7) or treated with NDGA daily (10mg/kg/day, i.p., n=4) from day 1. Direct RV catheterization was terminally performed to record RV pressure (RVP). Pulmonary arteriolar thickening and oxidized lipid deposition were assessed by staining lung sections with Masson’s Trichrome or with α-smooth muscle actin and E-06 (marker for oxidized low-density lipoproteins). In vitro, human pulmonary artery smooth muscle cell (hPASMC) proliferation was assessed by MTT assays in the absence or presence of 12-HETE (100ng/ml), 9-HODE (1µg/ml) and 13-HODE (1µg/ml) alone or together with NDGA (10, 25 and 50µM). In-vitro, HETE/HODE treatment increased hPASMC proliferation ~ 2-fold when compared to untreated cells and NDGA significantly inhibited the proliferative effects of all three oxidized lipids. In-vivo, NDGA treatment prevented the development of PH. RVP was lower in the NDGA-treated group vs. the PH group (24.01±1.39mmHg vs. 36.91±5.74mmHg, p<0.05) and was comparable to control normoxic mice (20.93±2.52mmHg). RV hypertrophy index was significantly elevated in the PH mice versus control mice (0.38±0.03 vs. 0.28±0.02 (p<0.001), while NDGA treatment completely prevented the development of RV hypertrophy (0.28±0.04). Lung sections demonstrated arteriolar thickening and E-06 positive deposits in the PH group, which was prevented by NDGA therapy. We conclude that oxidized fatty acid deposition and accumulation might play a role in the development of PH.


2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Priya Putta ◽  
Andrew H Smith ◽  
Pinaki Chaudhuri ◽  
Linda M Graham

During vascular intervention oxidized low-density lipoprotein (oxLDL) and lysophosphatidylcholine (lysoPC) accumulate at the site of arterial injury, which inhibits endothelial cell (EC) migration, and impedes endothelium healing. We have previously shown that lysoPC activates canonical transient receptor potential 6 (TRPC6) channel that leads to a prolonged [Ca2+]i influx, causing the inhibition in EC migration. We hypothesize that lysoPC activates phospholipase A 2 (PLA 2 ) crucial for TRPC6 activation; PLA 2 acts on cellular membranes to release arachidonic acid that opens arachidonate regulated calcium channel to release the initial calcium required to trigger TRPC6, blocking PLA 2 will prevent the opening of TRPC6 channels, preserve migration and promote endothelium healing. After incubation of bovine aortic EC with ATK or Ax048 to block PLA2G4, or with BEL, FKGK11, or FKGK18 to block PLA2G6, the effect of lysoPC-induced TRPC6 externalization and EC migration was assessed. Reversible PLA2G6 pharmacological inhibitors maximally blocked lysoPC-induced TRPC6 externalization, arachidonic acid release and preserved EC migration; exemplified with biotinylation assay, arachidonate enzyme assay, and razor scrape migration assay respectively. Immunofluorescence microscopy for TRPC6 plasma membrane translocation and PLA 2 enzyme activity assay supported these findings. To further verify the specific isoforms involved in blocking TRPC6 externalization, siRNA mediated transient knockdown studies were performed with PLA2G4A, PLA2G4C, PLA2G6A, and PLA2G6B siRNAs in EA.hy926— human endothelial cell line. PLA2G6A and not PLAG6B/4A/4C downregulation completely blocked TRPC6 externalization and preserved migration comparable to control levels. These studies confirmed the role of PLA2G6A (a calcium-independent cytosolic phospholipase A 2 group VI β isoform) in blocking lysoPC-induced TRPC6 activation and preservation of EC migration. Additional studies are in progress to confirm in vivo relevance of these findings. Our results show the potential for developing PLA 2 targeted therapies to block TRPC6 activation and promote endothelium healing, thus improving the outcomes for patients undergoing cardiovascular intervention.


2017 ◽  
Vol 39 (1) ◽  
Author(s):  
Katsuhito Kino ◽  
Masayo Hirao-Suzuki ◽  
Masayuki Morikawa ◽  
Akane Sakaga ◽  
Hiroshi Miyazawa

1992 ◽  
Vol 263 (4) ◽  
pp. E615-E623 ◽  
Author(s):  
O. L. Francone ◽  
G. Griffaton ◽  
A. D. Kalopissis

Triacylglycerol (TG) stored in cytoplasmic lipid droplets of hepatocytes was labeled by in vivo [1-(14)C]oleic acid injection to study the effect of a high-fat diet on its incorporation into very-low-density lipoproteins (VLDL). Compared with the control diet, hepatocytes of fat-fed rats 1) contained 7.6 times more cytoplasmic (floating fat) TG and 1.9 times more endoplasmic reticulum (microsomal) TG; 2) had 8 and 6 times lower TG specific activities in cytoplasm and endoplasmic reticulum, respectively; 3) incorporated 22% less 14C label into hepatocyte esterified lipids (TG, cholesterol, phospholipid); 4) secreted 48 and 33% less radioactive and total VLDL-TG, respectively; 5) oxidized more cytoplasmic TG-fatty acid (FA); and 6) showed a 50% decreased total utilization of stored TG-FA. With both diets, the lysosomal inhibitor chloroquine concomitantly decreased productions of labeled VLDL-TG, CO2, and acid-soluble oxidation products. The decreased incorporation of stored TG into VLDL-TG appreciably contributes to the overall inhibition of hepatic VLDL secretion by fat feeding. It appears to be related to the decreased mobilization rate of stored TG and its increased channelling toward oxidation.


2007 ◽  
Vol 293 (3) ◽  
pp. E776-E782 ◽  
Author(s):  
Paolo Tessari ◽  
Anna Coracina ◽  
Lucia Puricelli ◽  
Monica Vettore ◽  
Alessandra Cosma ◽  
...  

Nitric oxide (NO) is a key regulatory molecule with wide vascular, cellular, and metabolic effects. Insulin affects NO synthesis in vitro. No data exist on the acute effect of insulin on NO kinetics in vivo. By employing a precursor-product tracer method in humans, we have directly estimated the acute effect of insulin on intravascular NOx (i.e., the NO oxidation products) fractional (FSR) and absolute (ASR) synthesis rates in vivo. Nine healthy male volunteers were infused iv with l-[15N2-guanidino]arginine ([15N2]arginine) for 6 h. Timed measurements of 15NOx and [15N2]arginine enrichments in whole blood were performed in the first 3 h in the fasting state and then following a 3-h euglycemic-hyperinsulinemic clamp (with plasma insulin raised to ≈1,000 pmol/l). In the last 60 min of each experimental period, at ≈steady-state arginine enrichment, a linear increase of 15NOx enrichment (mean r = 0.9) was detected in both experimental periods. In the fasting state, NOx FSR was 27.4 ± 4.3%/day, whereas ASR was 0.97 ± 0.36 mmol/day, accounting for 0.69 ± 0.27% of arginine flux. Following hyperinsulinemia, both FSR and ASR of NOx increased (FSR by ≈50%, to 42.4 ± 6.7%/day, P < 0.005; ASR by ≈25%, to 1.22 ± 0.41 mmol/day, P = 0.002), despite a ≈20–30% decrease of arginine flux and concentration. The fraction of arginine flux used for NOx synthesis was doubled, to 1.13 ± 0.35% ( P < 0.003). In conclusion, whole body NOx synthesis can be directly measured over a short observation time with stable isotope methods in humans. Insulin acutely stimulates NOx synthesis from arginine.


1996 ◽  
Vol 42 (3) ◽  
pp. 440-444 ◽  
Author(s):  
I M Mackenzie ◽  
A Ekangaki ◽  
J D Young ◽  
C S Garrard

Abstract Nitric oxide is too short-lived to measure in vivo, but its production can be estimated by measuring its stable oxidation products, nitrites and nitrates, in serum. Renal elimination of these ions has been demonstrated, but the effect of renal function on their concentrations in serum is currently unknown. We evaluated serum and urine nitrates + nitrites as serum nitrogen oxides (sNOx), nitrogen oxide (NOx) clearance, and creatinine clearance in 71 patients on the Intensive Therapy Unit. The correlation between sNOx and plasma creatinine was strong and highly significant (P &lt;0.001). These results suggest that renal function has a significant effect on sNOx concentrations. Studies in which the sNOx concentration is used as an index of nitric oxide production can therefore be interpreted only if renal function has been taken into account.


Pteridines ◽  
2003 ◽  
Vol 14 (3) ◽  
pp. 88-93 ◽  
Author(s):  
Barbara Frick ◽  
Gabriele Neurauter ◽  
Antonio Diez-Ruiz ◽  
Katharina Schroecksnadel ◽  
Barbara Wirleitner ◽  
...  

Abstract Human monocyte-derived macrophages and dendritic cells produce increased amounts of neopterin derivatives upon stimulation with interferon-γ (IFN-γ). In parallel, such stimulated cells release a record of oxidizing specics as part of their cytocidal repertoire. Production of reactive oxygen species by stimulated immunocompetent cells may be the reason for the depletion of antioxidant vitamins and the development of oxidative stress during diseases with stimulated immune system. Noteworthy also neopterin derivatives are able to interfere with reactive oxygen, chlorine, and nitrogen species, and neopterin itself could contribute to oxidative stress. In vivo, neopterin concentrations thus allow not only to monitor cell-mediated immune response, they also allow to estimate the extent of oxidative stress which emerges during immune response. In certain diseases associations between higher neopterin levels and markers of oxidative stress have been reported. In neurodegenerative diseases, neopterin concentrations in scrum and cerebrospinal fluid also correlate with the cognitive decline in patients. In this studv we compared serum concentrations of neopterin with serum concentrations of peroxides and homocysteine in patients with various forms of dementia and in 5 healthy elderly controls. In patients of either form of dementia serum concentrations of peroxides and neopterin were increased compared to controls. There existed a positive correlation between age and concentrations of peroxides, neopterin and homocysteine. The data further supportile view that increased neopterin concentrations are associated with oxidative stress which could underlie c¡r increased demand of antioxidants in neurodegenerative disorders. It appears important that such changes can h> detected in the blood of patients with dementia, albeit its pathogenesis is considered to be confined to the brain The results further suggest that aging is associated with immune system activation which may lead to the increased production of peroxides.


2006 ◽  
Vol 401 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Barry Halliwell

‘Reactive species’ (RS) of various types are formed in vivo and many are powerful oxidizing agents, capable of damaging DNA and other biomolecules. Increased formation of RS can promote the development of malignancy, and the ‘normal’ rates of RS generation may account for the increased risk of cancer development in the aged. Indeed, knockout of various antioxidant defence enzymes raises oxidative damage levels and promotes age-related cancer development in animals. In explaining this, most attention has been paid to direct oxidative damage to DNA by certain RS, such as hydroxyl radical (OH•). However, increased levels of DNA base oxidation products such as 8OHdg (8-hydroxy-2′-deoxyguanosine) do not always lead to malignancy, although malignant tumours often show increased levels of DNA base oxidation. Hence additional actions of RS must be important, possibly their effects on p53, cell proliferation, invasiveness and metastasis. Chronic inflammation predisposes to malignancy, but the role of RS in this is likely to be complex because RS can sometimes act as anti-inflammatory agents.


Redox Biology ◽  
2014 ◽  
Vol 2 ◽  
pp. 878-883 ◽  
Author(s):  
Huiqin Zhong ◽  
Jianhong Lu ◽  
Lin Xia ◽  
Mingjiang Zhu ◽  
Huiyong Yin
Keyword(s):  

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