Levels Of Acrolein Research Articles

Air Starved Wood Crib Compartment Fire Heat Release and Toxic Gas Yields

4.6 kg pine wood crib fires were investigated in 1.6m3 fire compartment with air ventilation between 3 and 40 air changes per hour (ACH). The cribs were 380mm tall and 300mm square. The fires rapidly self extinguished at 3ACH and struggled to continue to propagate at 5 ACH, where only 15% of the initial crib mass was burnt. For 11, 21 and 37 ACH the cribs burned completely and the oxygen consumption HRR increased with ventilation. All three fully burned fires had rich equivalence ratios for most of the fire duration and associated high CO yields. Extremely toxic levels of CO, acrolein, formaldehyde and benzene were generated and the total toxic N on an LC50 basis was over 30. The combustion efficiency was very low due to the very high CO and total hydrocarbon emissions and this led to a major difference in the HRR by mass loss and that by oxygen consumption. The results demonstrate the severe toxic conditions that occur in ventilation restricted compartment fires with wood as the main fire load.

Air Starved Wood Crib Compartment Fire Heat Release and Toxic Gas Yields

Pine wood crib fires (4.6 kg) were investigated in a 1.6 m fire compartment with air ventilation between 3 and 40 air changes per hour (ACH). The cribs were 380 mm tall and 300 mm square. The fires rapidly self extinguished at 3ACH and struggled to continue to propagate at 5 ACH, where only 15 % of the initial crib mass was burnt. For 11, 21 and 37 ACH the cribs burned completely and the oxygen consumption HRR increased with ventilation. All three fully burned fires had rich equivalence ratios for most of the fire duration and associated high CO yields. Extremely toxic levels of CO, acrolein, formaldehyde and benzene were generated and the total toxic N on an LC50 basis was over 30. The combustion efficiency was very low due to the very high CO and total hydrocarbon emissions and this led to a major difference in the HRR by mass loss and that by oxygen consumption. The results demonstrate the severe toxic conditions that occur in ventilation restricted fires with wood as the main fire load.

Differentially-expressed genes related to atherosclerosis in acrolein-stimulated human umbilical vein endothelial cells

Acrolein is a highly reactive α, β-unsaturated aldehyde that is an environmental pollutant, a product of endogenous lipid peroxidation and a major component of cigarette smoke, which has been linked to the development of atherosclerotic vascular disease. Activation of endothelial cells by stimuli such as cigarette smoke is an important risk factor in atherosclerosis. Several studies have reported that acrolein levels are increased in atherosclerosis. Presently, a whole human DNA chip containing 24,000 genes was utilized to examine atherogenesis-related gene expression profiles of acrolein-stimulated human umbilical vein endothelial cells (HUVECs). Genes whose expression changed more than 2-fold included 3,174 up-regulated genes and 551 down-regulated genes. The affected genes included human atherogenesis-related genes such as cytokines, chemokines and adhesion molecules. These results support the view that acrolein-stimulated changes in HUVEC gene expression contribute to the development of atherosclerosis.

Molecular Regulations Induced by Acrolein in Neuroblastoma SK-N-SH Cells: Relevance to Alzheimer's Disease

Acrolein is the most reactive aldehyde among the by-products of lipid peroxidation. Growing evidence indicates that acrolein may play an important role in the pathogenesis of Alzheimer's disease (AD). In AD, levels of acrolein are significantly higher in hippocampus and temporal cortex regions of the brain. However, little is known about its toxicity in neuronal cells. Using the neuroblastoma cell line SK-N-SH, our results show that acrolein is toxic from 10 μM, but its toxicity does not induce the activation of caspase-3 and DNA fragmentation. Protein carbonylation and 4-hydroxynonenal levels were increased after 0.5 hr and 1 hr of treatment, respectively. Furthermore acrolein induced a biphasic effect on glutathione levels with a rapid depletion followed by a progressive increase. We have further investigated the regulation of different redox signaling pathways. A treatment with 10 μM of acrolein for 30 min activated NFκB while this activation was suppressed after a 24 hrs of treatment. In contrast, Nrf2 was activated only after 24 hrs of acrolein exposure. Consequently, the expression of heme oxygenase-1 and γ-glutamyl-cysteine-synthase were elevated after 24 hrs of acrolein treatment. Sirt-1 was also upregulated after 24 hrs of acrolein treatment. The p66Shc and ERK1/2 proteins are known to be involved in oxidative stress. Acrolein, at 10 μM, induced the phosphorylation of p66Shc and ERK1/2 only after a short period of treatment. Collectively, these data strengthen the contribution of acrolein in the induction of oxidative stress as observed in mild cognitive impairment and in AD brain.

Exposure to acrolein by inhalation causes platelet activation

Acrolein is a common air pollutant that is present in high concentrations in wood, cotton, and tobacco smoke, automobile exhaust and industrial waste and emissions. Exposure to acrolein containing environmental pollutants such as tobacco smoke and automobile exhaust has been linked to the activation of the coagulation and hemostasis pathways and thereby to the predisposition of thrombotic events in human. To examine the effects of acrolein on platelets, adult male C57Bl/6 mice were subjected acute (5 ppm for 6 h) or sub-chronic (1 ppm, 6 h/day for 4 days) acrolein inhalation exposures. The acute exposure to acrolein did not cause pulmonary inflammation and oxidative stress, dyslipidemia or induce liver damage or muscle injury. Platelet GSH levels in acrolein-exposed mice were comparable to controls, but acrolein-exposure increased the abundance of protein-acrolein adducts in platelets. Platelets isolated from mice, exposed to both acute and sub-chronic acrolein levels, showed increased ADP-induced platelet aggregation. Exposure to acrolein also led to an increase in the indices of platelet activation such as the formation of platelet-leukocyte aggregates in the blood, plasma PF4 levels, and increased platelet-fibrinogen binding. The bleeding time was decreased in acrolein exposed mice. Plasma levels of PF4 were also increased in mice exposed to environmental tobacco smoke. Similar to inhalation exposure, acrolein feeding to mice also increased platelet activation and established a pro-thrombotic state in mice. Together, our data suggest that acrolein is an important contributing factor to the pro-thrombotic risk in human exposure to pollutants such as tobacco smoke or automobile exhaust, or through dietary consumption.

Modulation of Hydrogen Peroxide and Acrolein-Induced Oxidative Stress, Mitochondrial Dysfunctions and Redox Regulated Pathways by the Bacopa Monniera Extract: Potential Implication in Alzheimer's Disease

Acrolein is one of the by-products of lipid peroxidation. Due to its high reactivity, it is not only a marker of lipid peroxidation but could also be an initiator of oxidative stress by adducting cellular nucleophilic groups. In brains of Alzheimer's disease (AD) patients, levels of acrolein are significantly higher in vulnerable brain region and, on primary hippocampal culture, it is more toxic than 4-hydroxyl-nonenal. The toxicity of the amyloid-beta peptide is mediated through the generation of hydrogen peroxide (H2O2). The actions of H2O2 include oxidative modifications of proteins, lipids, and DNA as observed in AD. Bacopa monniera (BM) has a long history of use in India as a memory-enhancing therapy. The objective of our study was to investigate the neuroprotective effects of the standardized extracts of BM against acrolein and H2O2 and to elucidate the mechanisms underlying this protection. Our results show that a pre-treatment with the BM extract protected the human neuroblastoma cell line SK-N-SH against H2O2 and acrolein. We demonstrated that BM pre-treatment significantly inhibited the generation of intracellular reactive oxygen species in addition to preserving the mitochondrial membrane potential. BM pre-treatment also prevented the modifications of the activity of several redox regulated proteins, i.e., NF-kappaB, Sirt1, ERK1/2, and p66Shc, so as to favor cell survival in response to oxidative stress. Thus, our findings demonstrate that BM can protect human neuroblastoma cells against H2O2 and acrolein through different mechanisms involved in the pathophysiology of AD and could have a therapeutic application in the prevention of AD.

Correlation between images of silent brain infarction, carotid atherosclerosis and white matter hyperintensity, and plasma levels of acrolein, IL-6 and CRP

Objective We found previously that the measurement of plasma levels of protein-conjugated acrolein (PC-Acro) together with IL-6 and CRP can be used to identify silent brain infarction (SBI) with high sensitivity and specificity. The aim of this study was to clarify how three biochemical markers are correlated to SBI, carotid atherosclerosis (CA) and white matter hyperintensity (WMH). Methods The levels of PC-Acro, IL-6 and CRP in plasma were measured by ELISA. SBI and WMH were evaluated by MRI, and CA was evaluated by duplex carotid ultrasonography. Results A total of 790 apparently healthy volunteers were classified into 260 control, 214 SBI, 263 CA and 245 WMH subjects, which included 187 subjects with two or three pathologies. When the combined measurements of PC-Acro, IL-6 and CRP were evaluated together with age, using a receiver operating characteristic curve and artificial neural networks, the relative risk value (RRV), an indicator of tissue damage, was in the order SBI with CA (0.90) > SBI (0.80) > CA (0.76) > WMH with CA (0.65) > WMH (0.46) > control (0.14). RRV was also correlated with severity in each group of SBI, CA and WMH. Conclusion The RRV supports the idea that the degree of risk to develop a stroke is in the order SBI > CA > WMH.

Increased levels of 4-hydroxynonenal and acrolein in the brain in preclinical Alzheimer disease

Previous studies demonstrate increased levels of 4-hydroxynonenal (HNE) and acrolein in vulnerable brain regions of subjects with mild cognitive impairment and late-stage Alzheimer disease (LAD). Recently preclinical AD (PCAD) subjects, who demonstrate normal antemortem neuropsychological test scores but abundant AD pathology at autopsy, have become the focus of increased study. Levels of extractable HNE and acrolein were quantified by gas chromatography–mass spectrometry with negative chemical ionization, and protein-bound HNE and acrolein were quantified by dot-blot immunohistochemistry in the hippocampus/parahippocampal gyrus (HPG), superior and middle temporal gyri (SMTG), and cerebellum (CER) of 10 PCAD and 10 age-matched normal control (NC) subjects. Results of the analyses show a significant ( P < 0.05) increase in levels of extractable acrolein in the HPG of PCAD subjects compared to age-matched NC subjects and a significant decrease in extractable acrolein in PCAD CER. Significant increases in protein-bound HNE in HPG and a significant decrease in CER of PCAD subjects compared to NC subjects were observed. No significant alterations were observed in either extractable or protein-bound HNE or acrolein in the SMTG of PCAD subjects. Additionally, no significant differences in levels of protein carbonyls were observed in the HPG, SMTG, or CER of PCAD subjects compared to NC subjects.

Toxicity of smoke extracts towards A549 lung cells: Role of acrolein and suppression by carbonyl scavengers

The noxious 3-carbon electrophile acrolein forms on combustion of diverse organic matter including synthetic polymers such as polyethylene. While known to play a key role in smoke inhalation injury (SII), the molecular basis for the pulmonary toxicity of high dose acrolein-containing smoke is unclear. As a result, drug interventions in SII are poorly directed against pathogenetic smoke toxicants such as acrolein. The first aim of this study was to confirm a role for acrolein in the acute toxicity of smoke extracts towards A549 lung cells by monitoring adduction of known acrolein targets and the expression of acrolein-inducible genes. A second aim was to evaluate carbonyl scavengers for their abilities to protect cell targets and block smoke extract toxicity. Extracts were prepared by bubbling smoke released by smouldering polyethylene through a buffered saline-trap. Acrolein levels in the extracts were estimated via HPLC after derivatisation with 2,4-dinitrophenylhydrazine. Extracts were highly toxic towards A549 cells, eliciting greater ATP depletion than an equivalent concentration of acrolein alone. The toxicity was accompanied by pronounced carbonylation of several cytoskeletal targets, namely vimentin and keratins-7, -8 and -18. Western blotting revealed that polyethylene combustion products also upregulated several acrolein-responsive protein markers, including GADD45β, NQO1, HMOX, Hsp70, Nur77 and Egr1. Several carbonyl scavengers (bisulfite, d-penicillamine, hydralazine and 1-hydrazinoisoquinoline) strongly attenuated smoke extract toxicity, with bisulfite suppressing both the adduction and cross-linking of intermediate filament targets. Bisulfite also suppressed the cytotoxicity of smoke extracts when detected using real-time monitoring of cellular impedance. These findings confirm a key role for acrolein in smoke cytotoxicity and suggest drugs that block acrolein toxicity deserve further investigation as possible interventions against SII.

Identification of acrolein-conjugated protein in plasma of patients with brain infarction

It is known that the level of protein-conjugated acrolein in plasma is a good marker of chronic renal failure and brain infarction. Thus, studies were carried out to determine which kinds of plasma proteins are conjugated with acrolein. It was found that acrolein was mainly conjugated with albumin. Tandem mass spectrometry analysis demonstrated that Lys-557 and Lys-560, located at the surface of domain III of albumin, were the major sites conjugated with acrolein. This is the first report to identify the amino acid residues in a protein modified by acrolein in vivo. It was found that conjugation of acrolein with albumin contributed to a decrease in the toxicity of acrolein.

Cell Death and Learning Impairment in Mice Caused by in Vitro Modified Pro-NGF Can Be Related to Its Increased Oxidative Modifications in Alzheimer Disease

Pro-nerve growth factor (pro-NGF) is expressed at increased levels in Alzheimer's disease (AD)-affected brains and is able to induce cell death in cultures; however, the reasons for these phenomena remain elusive. Here we show that pro-NGF in human AD-affected hippocampus and entorhinal cortex is modified by advanced glycation and lipoxidation end-products in a stage-dependent manner. These modifications block pro-NGF processing to mature NGF, thus making the proneurotrophin especially effective in inducing apoptosis of PC12 cells in culture through the p75 neurotrophin receptor. The processing of advanced glycation and lipoxidation end-products in vitro modified recombinant human pro-NGF is severely impaired, as evidenced by Western blot and by examining its physiological functionality in cell cultures. We also report that modified recombinant human pro-NGF, as well as pro-NGF isolated from human brain affected by AD, cause impairment of learning tasks when administered intracerebroventricularly in mice, which correlates with AD-associated learning impairment. Taken together, the data we present here offer a novel pathway of ethiopathogenesis in AD caused by advanced glycation and lipoxidation end-products modification of pro-NGF.

Indoor acrolein emission and decay rates resulting from domestic cooking events

Acrolein (2-propenal) is a common constituent of both indoor and outdoor air, can exacerbate asthma in children, and may contribute to other chronic lung diseases. Recent studies have found high indoor levels of acrolein and other carbonyls compared to outdoor ambient concentrations. Heated cooking oils produce considerable amounts of acrolein, thus cooking is likely an important source of indoor acrolein. A series of cooking experiments were conducted to determine the emission rates of acrolein and other volatile carbonyls for different types of cooking oils (canola, soybean, corn and olive oils) and deep-frying different food items. Similar concentrations and emission rates of carbonyls were found when different vegetable oils were used to deep-fry the same food product. The food item being deep-fried was generally not a significant source of carbonyls compared to the cooking oil. The oil cooking events resulted in high concentrations of acrolein that were in the range of 26.4–64.5 μg m −3. These concentrations exceed all the chronic regulatory exposure limits and many of the acute exposure limits. The air exchange rate and the decay rate of the carbonyls were monitored to estimate the half-life of the carbonyls. The half-life for acrolein was 14.4 ± 2.6 h, which indicates that indoor acrolein concentrations can persist for considerable time after cooking in poorly-ventilated homes.

Intense Correlation Between Brain Infarction and Protein-Conjugated Acrolein

We recently found that increases in plasma levels of protein-conjugated acrolein and polyamine oxidases, enzymes that produce acrolein, are good markers for stroke. The aim of this study was to determine whether the level of protein-conjugated acrolein is increased and levels of spermine and spermidine, the substrates of acrolein production, are decreased at the locus of infarction. A unilateral infarction was induced in mouse brain by photoinduction after injection of Rose Bengal. The volume of the infarction was analyzed using the public domain National Institutes of Health image program. The level of protein-conjugated acrolein at the locus of infarction and in plasma was measured by Western blotting and enzyme-linked immunosorbent assay, respectively. The levels of polyamines at the locus of infarction and in plasma were measured by high-performance liquid chromatography. The level of protein-conjugated acrolein was greatly increased, and levels of spermine and spermidine were decreased at the locus of infarction at 24 hours after the induction of stroke. The size of infarction was significantly decreased by N-acetylcysteine, a scavenger of acrolein. It was also found that the increases in the protein-conjugated acrolein, polyamines, and polyamine oxidases in plasma were observed after the induction of stroke. The results indicate that the induction of infarction is well correlated with the increase in protein-conjugated acrolein at the locus of infarction and in plasma.

Matrix Metalloproteinase-14 Mediates a Phenotypic Shift in the Airways to Increase Mucin Production

Induced mainly by cigarette smoking, chronic obstructive pulmonary disease (COPD) is a global public health problem characterized by progressive difficulty in breathing and increased mucin production. Previously, we reported that acrolein levels found in COPD sputum could activate matrix metalloproteinase-9 (MMP9). To determine whether acrolein increases expression and activity of MMP14, a critical membrane-bound endopeptidase that can initial a MMP-activation cascade. MMP14 activity and adduct formation were measured following direct acrolein treatment. MMP14 expression and activity was measured in human airway epithelial cells. MMP14 immunohistochemistry was performed with COPD tissue, and in acrolein- or tobacco-exposed mice. In a cell-free system, acrolein, in concentrations equal to those found in COPD sputum, directly adducted cysteine 319 in the MMP14 hemopexin-like domain and activated MMP14. In cells, acrolein increased MMP14 activity, which was inhibited by a proprotein convertase inhibitor, hexa-d-arginine. In the airway epithelium of COPD subjects, immunoreactive MMP14 protein increased. In mouse lung, acrolein or tobacco smoke increased lung MMP14 activity and protein. In cells, acrolein-induced MMP14 transcripts were inhibited by an epidermal growth factor receptor (EGFR) neutralizing antibody, EGFR kinase inhibitor, metalloproteinase inhibitor, or mitogen-activated protein kinase (MAPK) 3/2 or MAPK8 inhibitors, but not a MAPK14 inhibitor. Decreasing the MMP14 protein and activity in vitro by small interfering (si)RNA to MMP14 diminished the acrolein-induced MUC5AC transcripts. In acrolein-exposed mice or transgenic mice with lung-specific transforming growth factor-alpha (an EGFR ligand) expression, lung MMP14 and MUC5AC levels increased and these effects were inhibited by a EGFR inhibitor, erlotinib. Taken together, these findings implicate acrolein-induced MMP14 expression and activity in mucin production in COPD.

Respiratory Irritants in Australian Bushfire Smoke: Air Toxics Sampling in a Smoke Chamber and During Prescribed Burns

Bushfire smoke contains an array of organic and inorganic compounds, including respirable and inspirable particles, aldehydes, and carbon monoxide. These compounds have been found to be a health hazard for firefighters in the United States. Despite the high frequency of bushfires in Australia, analyses of bushfire smoke components are scarce. As part of an occupational health study investigating the respiratory health effects of bushfire smoke in firefighters, air toxics sampling was undertaken in a smoke chamber and during prescribed burns. Levels of formaldehyde and acrolein were demonstrated at respectively 60% and 80% of the Short Term Exposure Limit in the smoke chamber. Carbon monoxide levels exceeded the peak limit of 400 ppm significantly. Although concentrations were lower during the prescribed burns, the study shows that Australian bushfire smoke contains air toxics of concern and provides justification for further research into the levels of air toxics measured at bushfires and the associated health impacts.

Acrolein health effects

Acrolein is a chemical used as an intermediate reactive aldehyde in chemical industry. It is used for synthesis of many organic substances, methionine production, and methyl chloride refrigerant. The general population is exposed to acrolein via smoking, second-hand smoke, exposure to wood and plastic smoke. Firefighters and population living or working in areas with heavy automotive traffic may expose to higher level of acrolein via inhalation of smoke or automotive exhaust. Degradation of acrolein in all environmental media occurs rapidly, therefore, environmental accumulation is not expected. Acrolein degrade in 6A days when applied to surface water, and it has not been found as a contaminant in municipal drinking water. Acrolein vapor may cause eye, nasal and respiratory tract irritations in low level exposure. A decrease in breathing rate was reported by volunteers acutely exposed to 0.3A ppm of acrolein. At similar level, mild nasal epithelial dysplasia, necrosis, and focal basal cell metaplasia have been observed in rats. The acrolein effects on gastrointestinal mucosa in the animals include epithelial hyperplasia, ulceration, and hemorrhage. The severity of the effects is dose dependent. Acrolein induces the respiratory, ocular, and gastrointestinal irritations by inducing the release of peptides in nerve terminals innervating these systems. Levels of acrolein between 22 and 249 ppm for 10 min induced a dose-related decrease in substance P (a short-chain polypeptide that functions as a neurotransmitter or neuromodulator).

Acrolein, IL-6 and CRP as markers of silent brain infarction

We found previously that increased levels of polyamine oxidase (PAO) [acetylpolyamine oxidase (AcPAO) plus spermine oxidase (SMO)], and acrolein (CH 2 CHCHO) are good markers of stroke. We then investigated whether silent brain infarction (SBI) can be detected by measuring acrolein, PAO, or other biomarkers. Several biomarkers were measured in the plasma of 53 normal subjects and 44 subjects with SBI. It was found that the levels of protein-conjugated acrolein (PC-Acro), interleukin-6 (IL-6) and C-reactive protein (CRP) were significantly higher in SBI than in normal subjects. PAO was slightly higher in SBI than in normal subjects. Since the probability of SBI was increased with age, values were analyzed including age as a factor. When the combined measurements of PC-Acro, IL-6 and CRP were evaluated together with age using a receiver operating characteristic curve, SBI was indicated with 89% sensitivity and 91% specificity. The results indicate that measurement of PC-Acro together with IL-6 and CRP makes it possible to identify SBI with high sensitivity and specificity.

Escherichia coli YqhD Exhibits Aldehyde Reductase Activity and Protects from the Harmful Effect of Lipid Peroxidation-derived Aldehydes

Evidence that Escherichia coli YqhD is involved in bacterial response to compounds that generate membrane lipid peroxidation is presented. Overexpression of yqhD results in increased resistance to the reactive oxygen species-generating compounds hydrogen peroxide, paraquat, chromate, and potassium tellurite. Increased tolerance was also observed for the lipid peroxidation-derived aldehydes butanaldehyde, propanaldehyde, acrolein, and malondialdehyde and the membrane-peroxidizing compound tert-butylhydroperoxide. Expression of yqhD was also associated with changes in the concentration of intracellular peroxides and cytoplasmic protein carbonyl content and with a reduction in intracellular acrolein levels. When compared with the wild type strain, an yqhD mutant exhibited a sensitive phenotype to all these compounds and also augmented levels of thiobarbituric acid-reactive substances, which may indicate an increased level of lipid peroxidation. Purified YqhD catalyzes the in vitro reduction of acetaldehyde, malondialdehyde, propanaldehyde, butanaldehyde, and acrolein in a NADPH-dependent reaction. Finally, yqhD transcription was induced in cells that had been exposed to conditions favoring lipid peroxidation. Taken together these results indicate that this enzyme may have a physiological function by protecting the cell against the toxic effect of aldehydes derived from lipid oxidation. We speculate that in Escherichia coli YqhD is part of a glutathione-independent, NADPH-dependent response mechanism to lipid peroxidation.

Plasma acrolein levels and their association with delayed ischemic neurological deficits following aneurysmal subarachnoid haemorrhage: a pilot study

Background: The molecular mechanisms of cerebral vasospasm following aneurysmal subarachnoid haemorrhage (aSAH) remain unclear. Acrolein, a reactive metabolite produced in many models of mechanical and ischemic injury, has been shown to cause vasospasm in coronary artery and aorta models. These traits suggest it may play a role in post-aSAH cerebral vasospasm. This pilot study was designed as a preliminary investigation to determine if acrolein levels could be used as a clinical tool to predict the presence of vasospasm.Methods: Eleven patients with aSAH and Hunt and Hess admission grades of III–V were prospectively enrolled. Patients were stratified according to the presence or absence of vasospasm, defined as a delayed ischaemic neurological deficit in which all other possible causes have been excluded. Soluble acrolein levels were determined at two times points: early (day 1–3 post-SAH) and late (day 8–12 post-SAH) and the change in acrolein levels over this period was computed using a Mann–Whitney test.Results: The change in acrolein levels over this period between the vasospasm and non-vasospasm group trended toward but did not achieve statistical significance (means: 5.68 versus –5.54; medians: 5.27 versus –3.99; range: –8.067 to 22.904 versus –13.83 to 5.199 p=0.13). Five out of six vasospasm patients showed an increase in acrolein levels over the vasospasm period. Three out of four non-vasospasm patients showed a decrease over the vasospasm period.Conclusions: The results of this pilot study suggest that acrolein levels increase in patients undergoing vasospasm during the vasospasm window. This suggests that acrolein may play a role in the pathways leading up to or following vasospasm. There is a need for larger more definitive studies.

Antithrombin activity is inhibited by acrolein and homocysteine thiolactone: Protection by cysteine

Conditions in which serum or tissue acrolein levels are high (e.g.: renal failure, heavy smoking, oxidative stress) are also associated with increased thrombogenicity. Another emerging cardiovascular risk factor is homocysteine, and its derivative, homocysteine thiolactone. Antithrombin is one of the most important inhibitors of blood coagulation Since its activation by heparin binding requires critical interactions involving 3 Lys residues; we hypothesized that acrolein or homocysteine thiolactone impair antithrombin activity. When we incubated human antithrombin with increasing concentrations of acrolein (0–2 mmol/L) over a short period of time (0–4 h), a time and concentration dependent loss of activity was apparent (IC50=0.25 mmol/L). At 2 mmol/L, maximum inhibition (60%) is achieved at 1 h. This loss of activity was mirrored by changes in the electrophoretic pattern (homogeneity of the native antithrombin band as well as polymerization). In the same conditions, homocysteine thiolactone produces a significant, yet far less pronounced effect; acrolein being 3 times more potent than homocysteine thiolactone. When antithrombin was co-incubated with acrolein and cysteine, only less than 10% of antithrombin activity was lost. Aminoguanidine or carnosine displayed a significant yet, minor protective effect. The results suggest that in conditions where circulating or local acrolein concentrations are increased (atheroma plaque, thrombosis, sites of lipoperoxidation, smokers), acrolein-mediated loss of antithrombin activity could be a plausible phenomenon. This could contribute to explain increased thrombogenicity in smokers and in other conditions, as well as pointing at dietary intervention or the use of thiol-conserving reducing compounds as putative coadjuvant therapeutic measures.