Ornithine decarboxylase is involved in repair of small intestine after ischemia-reperfusion in rats

1991 ◽  
Vol 261 (3) ◽  
pp. G523-G529 ◽  
Author(s):  
K. Fujimoto ◽  
D. N. Granger ◽  
V. H. Price ◽  
P. Tso
Keyword(s):  
Ornithine Decarboxylase ◽  
Ischemia Reperfusion ◽  
Arterial Occlusion ◽  
Repair Process ◽  
Lipid Absorption ◽  
Lipid Transport ◽  
Irreversible Inhibitor ◽  
Complete Restoration ◽  
Series Of Experiments ◽  
Lymph Lipid

To assess whether ornithine decarboxylase (ODC) is involved in mucosal repair after ischemia-reperfusion (I/R), two approaches were used: 1) measurement of mucosal ODC activity at different intervals after I/R, and 2) inhibition of ODC activity with alpha-difluoromethylornithine (DFMO, an irreversible inhibitor). In the first series of experiments, rats were allowed to recover after superior mesenteric arterial occlusion (10 min) before harvesting the intestinal mucosa for measurement of ODC activity. ODC activity increased markedly 6 h after I/R, and greater than 72 h were required for enzyme activity to return to normal. DFMO treatment completely abolished the I/R-induced increase in ODC activity. In another series of experiments, rats with an intestinal lymph fistula were infused intraduodenally at 3 ml/h with vehicle or 2% DFMO in vehicle immediately after I/R. Lipid absorption was measured at 24 and 48 h after I/R. In the DFMO group, lymph radioactive lipid output at 24 h after I/R was significantly lower compared with time-matched sham-operated controls. Lymph lipid output in rats receiving the vehicle was restored to a normal level at 48 h after I/R. However, this restoration of normal lymphatic lipid transport at 48 h I/R was not observed in the DFMO group. These observations indicate that ODC activity plays an important role in the repair process that results in complete restoration of mucosal function 2 days after I/R.

Polyamine-mediated regulation of mouse ornithine decarboxylase is posttranslational

1989 ◽  
Vol 9 (12) ◽  
pp. 5484-5490
Author(s):  
T van Daalen Wetters ◽  
M Macrae ◽  
M Brabant ◽  
A Sittler ◽  
P Coffino
Keyword(s):  
Ornithine Decarboxylase ◽  
Translational Regulation ◽  
Feedback Inhibition ◽  
Chimeric Protein ◽  
Sequence Information ◽  
Pulse Label ◽  
Protein Coding ◽  
Coding Sequence ◽  
Series Of Experiments ◽  
The Difference

The activity of ornithine decarboxylase (ODC) is negatively regulated by intracellular polyamines, which thereby mediate a form of feedback inhibition of the initial enzyme in the pathway of their synthesis. This phenomenon has been believed to result, at least in part, from translational regulation. To investigate this further, we performed four series of experiments. First, we found that a chimeric protein encoded by an mRNA containing the ODC 5' leader sequence did not exhibit polyamine-dependent regulation. Second, we showed that transcripts containing the protein-coding sequence of ODC, but no other ODC-derived sequence information, exhibited regulation. Third, we found that the association of ODC mRNA with ribosomes was not altered when intracellular polyamine levels were modulated under conditions previously deemed to cause translational regulation. Last, we carried out experiments to measure the incorporation of [35S]methionine into ODC in polyamine-starved and polyamine-replete cells. Differential incorporation diminished progressively as pulse-label times were shortened; at the shortest labeling time used (4 min), the difference in favor of ODC in polyamine-starved cells was less than twofold. These findings suggest that it is necessary to reevaluate the question of whether polyamines cause alterations of translation of ODC mRNA.

Blockade of platelet-mediated relaxation in rat aortic rings exposed to xanthine-xanthine oxidase

1994 ◽  
Vol 266 (6) ◽  
pp. H2212-H2219 ◽  
Author(s):  
B. C. Yang ◽  
S. Khan ◽  
J. L. Mehta
Keyword(s):  
Free Radicals ◽  
Xanthine Oxidase ◽  
Hydroxyl Radicals ◽  
Vascular Tone ◽  
Oxygen Free Radicals ◽  
Ischemia Reperfusion ◽  
Arterial Occlusion ◽  
Superoxide Anions ◽  
Vascular Tissues ◽  
Hydroxyl Radical Scavengers

Platelet-induced relaxation of endothelium-intact vascular tissues, mediated via release of endothelium-derived relaxing factor (EDRF), is diminished or lost after ischemia and reperfusion. Release of oxygen free radicals during ischemia-reperfusion may degrade EDRF and influence response of vascular tissues to platelets. To determine platelet modulation of tone of blood vessels treated with oxygen free radicals, rat aortic rings with intact endothelium were exposed to xanthine (X) plus xanthine oxidase (XO) 5 min before contraction with norepinephrine followed by exposure of rings to platelets. Treatment of aortic rings with X+XO caused a modest contraction, potentiated norepinephrine-mediated contraction, and inhibited platelet-mediated vasorelaxation. Exposure of aortic rings to X+XO also decreased ADP- as well as acetylcholine-mediated relaxation. Pretreatment of rings with superoxide dismutase or catalase did not change X+XO-induced inhibition of platelet-mediated relaxation, but it abolished the X+XO-induced contraction of rings as well as subsequent potentiation of norepinephrine-mediated contraction. Pretreatment of rings with hydroxyl radical scavengers dimethyl-2-thiourea, dimethyl sulfoxide, mannitol, or histidine attenuated the X+XO-induced inhibition of platelet-mediated relaxation, although these agents did not affect X+XO-induced contraction of rings. This study indicates that the vasoconstriction on exposure of aortic rings to X+XO is due to generation of superoxide anions, whereas inhibition of platelet-mediated relaxation after exposure of vessels to X+XO is due, at least in part, to release of hydroxyl radicals. Release of superoxide anions and hydroxyl radicals after temporary arterial occlusion may be the basis of subsequent modulation of vascular tone.

scholarly journals Response of enzymes involved in the metabolism of polyamines to phytohaemagglutinin-induced activation of human lymphocytes

1981 ◽  
Vol 196 (3) ◽  
pp. 733-738 ◽  
Author(s):  
H Korpela ◽  
E Hölttä ◽  
T Hovi ◽  
J Jänne
Keyword(s):  
Ornithine Decarboxylase ◽  
Human Lymphocytes ◽  
Lymphocyte Activation ◽  
Decarboxylase Activity ◽  
Spermidine Synthase ◽  
Irreversible Inhibitor ◽  
Adenosylmethionine Decarboxylase ◽  
Spermine Synthase ◽  
Diamine Oxidase Activity ◽  
Stimulation Of

The stimulation of lymphocyte ornithine decarboxylase and adenosylmethionine decarboxylase produced by phytohaemagglutinin was accompanied by an equally marked, but delayed, stimulation of spermidine synthase, which is not commonly considered as an inducible enzyme. In contrast with the marked stimulation of these biosynthetic enzymes, less marked changes were observed in the biodegradative enzymes of polyamines in response to phytohaemagglutinin. Diamine oxidase activity was undetectable during all stages of the transformation. The activity of polyamine oxidase remained either constant or was slightly decreased several days after addition of the mitogen. The activity of polyamine acetylase (employing all the natural polyamines as substrates) distinctly increased both in the cytosolic and crude nuclear preparations of the cells during later stages of mitogen activation. Difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase, although powerfully inhibiting ornithine decarboxylase, produced a gradual enhancement of adenosylmethionine decarboxylase activity during lymphocyte activation, without influencing the activities of the two propylamine transferases (spermidine synthase and spermine synthase).

scholarly journals Polyamine-mediated regulation of mouse ornithine decarboxylase is posttranslational.

1989 ◽  
Vol 9 (12) ◽  
pp. 5484-5490 ◽  
Author(s):  
T van Daalen Wetters ◽  
M Macrae ◽  
M Brabant ◽  
A Sittler ◽  
P Coffino
Keyword(s):  
Ornithine Decarboxylase ◽  
Translational Regulation ◽  
Feedback Inhibition ◽  
Chimeric Protein ◽  
Sequence Information ◽  
Pulse Label ◽  
Protein Coding ◽  
Coding Sequence ◽  
Series Of Experiments ◽  
The Difference

The activity of ornithine decarboxylase (ODC) is negatively regulated by intracellular polyamines, which thereby mediate a form of feedback inhibition of the initial enzyme in the pathway of their synthesis. This phenomenon has been believed to result, at least in part, from translational regulation. To investigate this further, we performed four series of experiments. First, we found that a chimeric protein encoded by an mRNA containing the ODC 5' leader sequence did not exhibit polyamine-dependent regulation. Second, we showed that transcripts containing the protein-coding sequence of ODC, but no other ODC-derived sequence information, exhibited regulation. Third, we found that the association of ODC mRNA with ribosomes was not altered when intracellular polyamine levels were modulated under conditions previously deemed to cause translational regulation. Last, we carried out experiments to measure the incorporation of [35S]methionine into ODC in polyamine-starved and polyamine-replete cells. Differential incorporation diminished progressively as pulse-label times were shortened; at the shortest labeling time used (4 min), the difference in favor of ODC in polyamine-starved cells was less than twofold. These findings suggest that it is necessary to reevaluate the question of whether polyamines cause alterations of translation of ODC mRNA.

Tetrahedral framework nucleic acids prevent retina ischemia-reperfusion injury from oxidative stress via activating the Akt/Nrf2 pathway

Nanoscale ◽  
2019 ◽  
Vol 11 (43) ◽  
pp. 20667-20675 ◽  
Author(s):  
Xin Qin ◽  
Ni Li ◽  
Mei Zhang ◽  
Shiyu Lin ◽  
Junyao Zhu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Diabetic Retinopathy ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Arterial Occlusion ◽  
Retinal Ischemia ◽  
Tetrahedral Framework ◽  
Nrf2 Pathway ◽  
Retinal Arterial Occlusion ◽  
Ophthalmic Diseases

Retinal ischemia-reperfusion (I/R) injuries are involved in the universal pathological processes of many ophthalmic diseases, including glaucoma, diabetic retinopathy, and retinal arterial occlusion.

scholarly journals Targeting HIF-1α to Prevent Renal Ischemia-Reperfusion Injury: Does It Work?

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Kapil Sethi ◽  
Kenny Rao ◽  
Damien Bolton ◽  
Oneel Patel ◽  
Joseph Ischia
Keyword(s):  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Tissue Injury ◽  
Ischemia Reperfusion ◽  
Arterial Occlusion ◽  
Small Animal ◽  
Kidney Injury ◽  
Renal Ischemia ◽  
Metabolic Adaptation ◽  
Critical Ischemia

Partial nephrectomy (open or minimally invasive) usually requires temporary renal arterial occlusion to limit intraoperative bleeding and improve access to intrarenal structures. This is a time-critical step due to the critical ischemia period of renal tissue. Prolonged renal ischemia may lead to irreversible nephron damage in the remaining tissue and, ultimately, chronic kidney disease. This is potentiated by the incompletely understood ischemia-reperfusion injury (IRI). A key mechanism in IRI prevention appears to be the upregulation of an intracellular transcription protein, Hypoxia-Inducible Factor (HIF). HIF mediates metabolic adaptation, angiogenesis, erythropoiesis, cell growth, survival, and apoptosis. Upregulating HIF-1α via ischemic preconditioning (IPC) or drugs that simulate hypoxia (hypoxia-mimetics) has been investigated as a method to reduce IRI. While many promising chemical agents have been trialed for the prevention of IRI in small animal studies, all have failed in human trials. The aim of this review is to highlight the techniques and drugs that target HIF-1α and ameliorate IRI associated with renal ischemia. Developing a technique or drug that could reduce the risk of acute kidney injury associated with renal IRI would have an immediate worldwide impact on multisystem surgeries that would otherwise risk ischemic tissue injury.

Role of polyamines in differentiation of 3T3-L1 fibroblasts into adipocytes

1984 ◽  
Vol 246 (3) ◽  
pp. C293-C300 ◽  
Author(s):  
B. G. Erwin ◽  
D. R. Bethell ◽  
A. E. Pegg
Keyword(s):  
Ornithine Decarboxylase ◽  
Biosynthetic Enzymes ◽  
Irreversible Inhibitor ◽  
Inhibition Of Differentiation ◽  
Increased Activity ◽  
Adipose Cells ◽  
Partial Reversal

The role of polyamines in the differentiation of 3T3-L1 fibroblasts into adipose cells was studied. This conversion was blocked by the addition of alpha-difluoromethylornithine, an enzyme-activated irreversible inhibitor of ornithine decarboxylase, which prevented a rise in spermidine content in the differentiating cells. The inhibition of differentiation could be overcome completely by the provision of exogenous putrescine, spermidine, or spermine. Partial reversal could be produced by exposure to nonphysiological homologues of the natural polyamines such as 1,3-diaminopropane, 1,5-diaminopentane, and sym-norspermine. Reversal of the inhibition of differentiation by exogenous polyamines required a period of exposure to the amines, indicating that the lack of differentiation is not due simply to an obligatory role for polyamines in the biosynthesis of lipids. These results indicate that spermidine is required for the differentiation, but spermidine alone was not able to replace insulin and 1-methyl-3-isobutylxanthine in stimulating conversion to adipocytes. Therefore spermidine appears to be necessary but not sufficient for differentiation to occur. Finally, the elevation of spermidine content that occurs during the conversion of fibroblasts to adipocytes did not correlate with an increased activity of the polyamine biosynthetic enzymes. This implies that the increase must be regulated by changes in the rate of degradation or excretion of the polyamines.

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