Thiyl radicals in biological systems: significant or trivial?

1995 ◽  
Vol 61 ◽  
pp. 55-63 ◽  
Author(s):  
B. Kalyanaraman
Keyword(s):  
Mammalian Cells ◽  
Hydrogen Abstraction ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Oxidative Modification ◽  
Addition Reactions ◽  
Thiyl Radicals ◽  
Protein Thiols ◽  
Spin Resonance

Thiyl radicals are formed from one-electron oxidation of thiols. Thiyl radicals participate in a number of reactions including electron transfer, hydrogen abstraction and addition reactions with several biological constituents and xenobiotics. Thiyl radicals can be detected by optical spectroscopy or by electron spin resonance (ESR) spectroscopy. Thiyl radicals appear to play a role in the nitrosylation of thiols and protein thiols. The exact mechanism of thiol-induced enhancement of oxidative modification of low-density lipoprotein remains questionable. The proposed role of thiyl radicals in lipid peroxidation needs to be re-examined. It has been proposed that thiyl radicals are detoxified by superoxide dismutase in mammalian cells and by a thiol-specific enzyme in bacterial systems. We propose that thiols or protein thiols act as potent antioxidants in radical-induced damage via formation of thiyl radicals.

Antiphospholipid antibodies and myocardial infarction

Lupus ◽  
1998 ◽  
Vol 7 (2_suppl) ◽  
pp. 132-134 ◽  
Author(s):  
O Vaarala
Keyword(s):  
Myocardial Infarction ◽  
Heart Disease ◽  
Antiphospholipid Antibodies ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Epidemiological Data ◽  
Oxidative Modification ◽  
Increased Risk ◽  
Different Types

In prospective studies, increased levels of cardiolipin-biding antibodies and autoantibodies to oxidized low-density lipoprotein (LDL) have been observed in patients with myocardial infarction (MI). These findings suggest that antiphospholipid antibodies may contribute to the development of MI. The ‘oxidative-modification hypothesis’ in the pathogenesis of atherosclerotic heart disease is based on the oxidation of LDL, its accumulation into arterial wall, and the development of chronic inflammation in the atheroma. Evidence of enhanced lipid peroxidation and its association with antiphospholipid antibodies has been recently reported in SLE patients. There is also epidemiological data showing a remarkably increased risk of MI in SLE. In this review, the role of different types of antiphospholipid antibodies in the development of atherosclerotic heart disease is evaluated with particular attention to their potential pathogenic mechanisms and the possibilities in the prevention of MI associated with antiphospholipid antibodies.

scholarly journals The role of oxidative stress and NADPH oxidase in the pathogenesis of atherosclerosis

2017 ◽  
Vol 71 (1) ◽  
pp. 57-68
Author(s):  
Dorota Bryk ◽  
Wioletta Olejarz ◽  
Danuta Zapolska-Downar
Keyword(s):  
Oxidative Stress ◽  
Nadph Oxidase ◽  
Low Density Lipoprotein ◽  
Experimental Studies ◽  
Density Lipoprotein ◽  
Oxidative Modification ◽  
Regulatory Subunits ◽  
Cell Migration And Proliferation ◽  
Nox Family

Reactive oxygen species (ROS) play a key role in the pathogenesis of atherosclerosis. The main mechanisms which are involved are low-density lipoprotein oxidative modification, inactivation of nitric oxide and modulation of redox-sensitive signaling pathways. ROS contribute to several aspects of atherosclerosis including endothelial cell dysfunction, monocyte/macrophage recruitment and activation, stimulation of inflammation, and inducing smooth muscle cell migration and proliferation. NADPH oxidase is the main source of ROS in the vasculature. This enzyme consists of a membrane-bound heterodimer of gp91phox and p22phox, cytosolic regulatory subunits p47phox, p67phox and p40phox, and small GTP-binding proteins rac1 and rac 2. Seven distinct isoforms of this enzyme have been identified, of which four (NOX1, 2, 4 and 5) may have cardiovascular function. In this paper, we review the current state of knowledge concerning the role of oxidative stress and NOX enzymes in pathogenesis of atherosclerosis. Moreover, we analyze the experimental studies that explore the relationship between the NOX family and atherosclerosis.

The Role of the Low-Density Lipoprotein Receptor-Related Protein (LRP) in the Plasma Clearance and Liver Uptake of Recombinant Single-chain Urokinase-type Plasminogen Activator in Rats

1997 ◽  
Vol 77 (04) ◽  
pp. 710-717 ◽  
Author(s):  
Marieke E van der Kaaden ◽  
Dingeman C Rijken ◽  
J Kar Kruijt ◽  
Theo J C van Berkel ◽  
Johan Kuiper
Keyword(s):  
Plasminogen Activator ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Single Chain ◽  
Liver Uptake ◽  
Type Plasminogen Activator ◽  
Parenchymal Liver ◽  
Urokinase Type Plasminogen Activator ◽  
Density Lipoprotein Receptor

SummaryUrokinase-type plasminogen activator (u-PA) is used as a thrombolytic agent in the treatment of acute myocardial infarction. In vitro, recombinant single-chain u-PA (rscu-PA) expressed in E.coli is recognized by the Low-Density Lipoprotein Receptor-related Protein (LRP) on rat parenchymal liver cells. In this study we investigated the role of LRP in the liver uptake and plasma clearance of rscu-PA in rats. A preinjection of the LRP inhibitor GST-RAP reduced the maximal liver uptake of 125I-rscu-PA at 5 min after injection from 50 to 30% of the injected dose and decreased the clearance of rscu-PA from 2.37 ml/min to 1.58 ml/min. Parenchymal, Kupffer and endothelial cells were responsible for 40, 50 and 10% of the liver uptake, respectively. The reduction in liver uptake of rscu-PA by the preinjection of GST-RAP was caused by a 91 % and 62% reduction in the uptake by parenchymal and Kupffer cells, respectively. In order to investigate the part of rscu-PA that accounted for the interaction with LRP, experiments were performed with a mutant of rscu-PA lacking residues 11-135 (= deltal25- rscu-PA). Deletion of residues 11-135 resulted in a 80% reduction in liver uptake and a 2.4 times slower clearance (0.97 ml/min). The parenchymal, Kupffer and endothelial cells were responsible for respectively 60, 33 and 7% of the liver uptake of 125I-deltal25-rscu-PA. Preinjection of GST-RAP completely reduced the liver uptake of delta 125-rscu-PA and reduced its clearance to 0.79 ml/min. Treatment of isolated Kupffer cells with PI-PLC reduced the binding of rscu-PA by 40%, suggesting the involvement of the urokinase-type Plasminogen Activator Receptor (u-PAR) in the recognition of rscu-PA. Our results demonstrate that in vivo LRP is responsible for more than 90% of the parenchymal liver cell mediated uptake of rscu-PA and for 60% of the Kupffer cell interaction. It is also suggested that u-PAR is involved in the Kupffer cell recognition of rscu-PA.

The Role of the Endothelium in Premature Atherosclerosis: Molecular Mechanisms

2020 ◽  
Vol 27 (7) ◽  
pp. 1041-1051 ◽  
Author(s):  
Michael Spartalis ◽  
Eleftherios Spartalis ◽  
Antonios Athanasiou ◽  
Stavroula A. Paschou ◽  
Christos Kontogiannis ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Low Density Lipoprotein ◽  
Critical Role ◽  
Density Lipoprotein ◽  
Number Of Genes ◽  
Causes Of Mortality ◽  
Artery Disease ◽  
Genetic And Environmental Factors ◽  
Made In

Atherosclerotic disease is still one of the leading causes of mortality. Atherosclerosis is a complex progressive and systematic artery disease that involves the intima of the large and middle artery vessels. The inflammation has a key role in the pathophysiological process of the disease and the infiltration of the intima from monocytes, macrophages and T-lymphocytes combined with endothelial dysfunction and accumulated oxidized low-density lipoprotein (LDL) are the main findings of atherogenesis. The development of atherosclerosis involves multiple genetic and environmental factors. Although a large number of genes, genetic polymorphisms, and susceptible loci have been identified in chromosomal regions associated with atherosclerosis, it is the epigenetic process that regulates the chromosomal organization and genetic expression that plays a critical role in the pathogenesis of atherosclerosis. Despite the positive progress made in understanding the pathogenesis of atherosclerosis, the knowledge about the disease remains scarce.

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