Fate and effects of acrolein

Protective Effect of Silymarin against Acrolein-Induced Cardiotoxicity in Mice

Reactive α,β-unsaturated aldehydes such as acrolein (ACR) are major components of environmental pollutants and have been implicated in the neurodegenerative and cardiac diseases. In this study, the protective effect of silymarin (SN) against cardiotoxicity induced by ACR in mice was evaluated. Studies were performed on seven groups of six animals each, including vehicle-control (normal saline + 0.5% w/v methylcellulose), ACR (7.5 mg/kg/day, gavage) for 3 weeks, SN (25, 50 and 100 mg/kg/day, i.p.) plus ACR, vitamin E (Vit E, 100 IU/kg, i.p.) plus ACR, and SN (100 mg/kg, i.p.) groups. Mice received SN 7 days before ACR and daily thereafter throughout the study. Pretreatment with SN attenuated ACR-induced increased levels of malondialdehyde (MDA), serum cardiac troponin I (cTnI), and creatine kinase-MB (CK-MB), as well as histopathological changes in cardiac tissues. Moreover, SN improved glutathione (GSH) content, superoxide dismutase (SOD), and catalase (CAT) activities in heart of ACR-treated mice. Western blot analysis showed that SN pretreatment inhibited apoptosis provoked by ACR through decreasing Bax/Bcl-2 ratio, cytosolic cytochrome c content, and cleaved caspase-3 level in heart. In conclusion, SN may have protective effects against cardiotoxicity of ACR by reducing lipid peroxidation, renewing the activities of antioxidant enzymes, and preventing apoptosis.

Effects of bioreactive acrolein from automotive exhaust gases on human cells in vitro

Acrolein is a toxic unsaturated aldehyde and widespread environmental pollutant produced during lipid peroxidation and also by burning of tobacco or liquid fuels. Inhalation or dermal exposure to acrolein could be toxic to organisms. This very reactive aldehyde has a strong affinity for binding to proteins thus forming pathogenic protein-adducts. In the present study we have analyzed formation of bioreactive acrolein-protein adducts in bovine serum albumin solution exposed to exhaust gases of mineral diesel fuel and of mineral diesel fuel supplemented with different amounts of a novel diesel fuel additive denoted Ecodiesel (produced by a genuine procedure of recycling of plant oils used for food preparation). The effects of acrolein-protein adducts were tested on human microvascular endothelial cells and on human osteosarcoma cells that are sensitive to bioactivities of lipid peroxidation products. The results have shown a reduction of the bioreactive acrolein in exhaust gases when mineral diesel was supplemented with 5-20% Ecodiesel. Moreover, acrolein-protein adducts obtained from mineral diesel supplemented with Ecodiesel were less toxic than those obtained from mineral diesel alone. Thus, we assume that supplementing mineral diesel fuel with Ecodiesel would be of benefit for the use of renewable energy, for environment and for human health due to reduced environmental pollution with bioreactive acrolein.

Effect of CpG methylation at different sequence context on acrolein- and BPDE-DNA binding and mutagenesis

Acrolein (Acr), an α,β-unsaturated aldehyde, is abundant in tobacco smoke and cooking and exhaust fumes. Acr induces mutagenic α- and γ- hydroxy-1,N(2)-cyclic propano-deoxyguanosine adducts in normal human bronchial epithelial cells. Our earlier work has found that Acr-induced DNA damage preferentially occurs at lung cancer p53 mutational hotspots that contain CpG sites and that methylation at CpG sites enhances Acr-DNA binding at these sites. Based on these results, we hypothesized that this enhancement of Acr-DNA binding leads to p53 mutational hotspots in lung cancer. In this study, using a shuttle vector supF system, we tested this hypothesis by determining the effect of CpG methylation on Acr-DNA binding and the mutations in human lung fibroblasts. We found that CpG methylation enhances Acr-induced mutations significantly. Although CpG methylation enhances Acr-DNA binging at all CpG sites, it enhances mutations at selective--TCGA--sites. Similarly, we found that CpG methylation enhances benzo(a)pyrene diol epoxide binding at all -CpG- sites. However, the methylated CpG sequences in which benzo(a)pyrene diol epoxide-induced mutations are enhanced are different from the CpG sequences in which Acr-induced mutations are enhanced. CpG methylation greatly increases Acr-induced G to T and G to A mutation frequency to levels similar to these types of mutations found in the CpG sites in the p53 gene in tobacco smoke-related lung cancer. These results indicate that both CpG sequence context and the chemical nature of the carcinogens are crucial factors for determining the effect of CpG methylation on mutagenesis.

Acrolein cytotoxicity in hepatocytes involves endoplasmic reticulum stress, mitochondrial dysfunction and oxidative stress

Acrolein is a common environmental, food and water pollutant and a major component of cigarette smoke. Also, it is produced endogenously via lipid peroxidation and cellular metabolism of certain amino acids and drugs. Acrolein is cytotoxic to many cell types including hepatocytes; however the mechanisms are not fully understood. We examined the molecular mechanisms underlying acrolein hepatotoxicity in primary human hepatocytes and hepatoma cells. Acrolein, at pathophysiological concentrations, caused a dose-dependent loss of viability of hepatocytes. The death was apoptotic at moderate and necrotic at high concentrations of acrolein. Acrolein exposure rapidly and dramatically decreased intracellular glutathione and overall antioxidant capacity, and activated the stress-signaling MAP-kinases JNK, p42/44 and p38. Our data demonstrate for the first time in human hepatocytes, that acrolein triggered endoplasmic reticulum (ER) stress and activated eIF2α, ATF-3 and -4, and Gadd153/CHOP, resulting in cell death. Notably, the protective/adaptive component of ER stress was not activated, and acrolein failed to up-regulate the protective ER-chaperones, GRP78 and GRP94. Additionally, exposure to acrolein disrupted mitochondrial integrity/function, and led to the release of pro-apoptotic proteins and ATP depletion. Acrolein-induced cell death was attenuated by N-acetyl cysteine, phenyl-butyric acid, and caspase and JNK inhibitors. Our data demonstrate that exposure to acrolein induces a variety of stress responses in hepatocytes, including GSH depletion, oxidative stress, mitochondrial dysfunction and ER stress (without ER-protective responses) which together contribute to acrolein toxicity. Our study defines basic mechanisms underlying liver injury caused by reactive aldehyde pollutants such as acrolein.

Understanding secondary injury

Secondary injury is a term applied to the destructive and self-propagating biological changes in cells and tissues that lead to their dysfunction or death over hours to weeks after the initial insult (the "primary injury"). In most contexts, the initial injury is usually mechanical. The more destructive phase of secondary injury is, however, more responsible for cell death and functional deficits. This subject is described and reviewed differently in the literature. To biomedical researchers, systemic and tissue-level changes such as hemorrhage, edema, and ischemia usually define this subject. To cell and molecular biologists, "secondary injury" refers to a series of predominately molecular events and an increasingly restricted set of aberrant biochemical pathways and products. These biochemical and ionic changes are seen to lead to death of the initially compromised cells and "healthy" cells nearby through necrosis or apoptosis. This latter process is called "bystander damage." These viewpoints have largely dominated the recent literature, especially in studies of the central nervous system (CNS), often without attempts to place the molecular events in the context of progressive systemic and tissue-level changes. Here we provide a more comprehensive and inclusive discussion of this topic.

Cigarette smoke enhances chemotaxis via acetylation of proline-glycine-proline

Several chronic lung diseases have been linked to cigarette smoking (Chronic Obstructive Pulmonary Disease (COPD), and cancer are associated with increased tobacco use). We recently described a collagen fragment, proline-glycine-proline (PGP), chemotactic for neutrophils, that appears to play a role in COPD, cystic fibrosis, and bronchiolitis obliterans syndrome. PGP can exist in either its native or acetylated form (NAcPGP), although the mechanism of N-terminal-acetylation remains unknown. This work investigates the possibility that cigarette smoke (CS) and its components acetylate PGP, describing a possible mechanism for some of the chronic inflammation seen in tobacco-associated disease. CSE and CSC (3.56 and 12.38 ng/ml NAcPGP respectively, p less than 0.01) and its components (acrolein, acetaldehyde, and methyl glyoxal) acetylated PGP (0.51, 1.03, and 0.23 ng/ml NAcPGP, p less than 0.01). Both N-acetyl-cysteine and carbocysteine (scavengers of reactive aldehydes) blocked chemical acetylation of PGP by CS (100 percent and 97 percent inhibition, respectively, p less than 0.01). NAcPGP is more chemoattractive to neutrophils, and less susceptible to degradation by Leukotriene-A4-Hydrolase (detected in the lung). These experiments propose a mechanism for the increased neutrophil recruitment seen in smoking-associated lung diseases.

Effect of a volatile smoke component (acrolein) on human gingival fibroblasts: An in vitro study

Aim:

Tobacco and some of its volatile and non-volatile components have been found to affect many types of cells including human gingival fibroblasts. The aim of this present study was to estimate the effect of acrolein, a volatile fraction of cigarette smoke on the attachment, proliferation and ultra structure of human gingival fibroblasts in culture.

Materials and Methods:

Human gingival fibroblasts strains obtained from healthy subjects aged 20-30 years, were grown to confluency and utilized between 3^rd -6^th passages. The cell cultures seeded in 96 well microtitration plates at a density of 45,000 cells/well were incubated with acrolein at concentrations of 10^-4, 3×10^-5 and 10^-5 . Attachment ability was evaluated after three hours using Neubauer hemocytometer. For the proliferation assay cell cultures seeded at a density of 10,000 cells/well were incubated at concentrations of 10^-4, 3×10^-5, 10^-5, 3×10^-6, 10^-6 and cell count determined after 5 days using a hemocytometer. Cell morphology was examined under phase contrast microscope.

Results:

Acrolein produced a dose-dependent cytotoxic effect on human gingival fibroblasts with complete inhibition of attachment and proliferation at higher concentrations.

Conclusion:

This supports the hypothesis that cigarette smoke is a great risk factor in the development and progression of periodontal disease.

Effect of carcinogenic acrolein on DNA repair and mutagenic susceptibility

Acrolein (Acr), a ubiquitous environmental contaminant, is a human carcinogen. Acr can react with DNA to form mutagenic α- and γ-hydroxy-1, N(2)-cyclic propano-2'-deoxyguanosine adducts (α-OH-Acr-dG and γ-OH-Acr-dG). We demonstrate here that Acr-dG adducts can be efficiently repaired by the nucleotide excision repair (NER) pathway in normal human bronchial epithelia (NHBE) and lung fibroblasts (NHLF). However, the same adducts were poorly processed in cell lysates isolated from Acr-treated NHBE and NHLF, suggesting that Acr inhibits NER. In addition, we show that Acr treatment also inhibits base excision repair and mismatch repair. Although Acr does not change the expression of XPA, XPC, hOGG1, PMS2 or MLH1 genes, it causes a reduction of XPA, XPC, hOGG1, PMS2, and MLH1 proteins; this effect, however, can be neutralized by the proteasome inhibitor MG132. Acr treatment further enhances both bulky and oxidative DNA damage-induced mutagenesis. These results indicate that Acr not only damages DNA but can also modify DNA repair proteins and further causes degradation of these modified repair proteins. We propose that these two detrimental effects contribute to Acr mutagenicity and carcinogenicity.

Chronic oral exposure to the aldehyde pollutant acrolein induces dilated cardiomyopathy

Environmental triggers of dilated cardiomyopathy are poorly understood. Acute exposure to acrolein, a ubiquitous aldehyde pollutant, impairs cardiac function and cardioprotective responses in mice. Here, we tested the hypothesis that chronic oral exposure to acrolein induces inflammation and cardiomyopathy. C57BL/6 mice were gavage-fed acrolein (1 mg/kg) or water (vehicle) daily for 48 days. The dose was chosen based on estimates of human daily unsaturated aldehyde consumption. Compared with vehicle-fed mice, acrolein-fed mice exhibited significant (P < 0.05) left ventricular (LV) dilatation (LV end-diastolic volume 36 ± 8 vs. 17 ± 5 μl), contractile dysfunction (dP/dt(max) 4,697 ± 1,498 vs. 7,016 ± 1,757 mmHg/s), and impaired relaxation (tau 15.4 ± 4.3 vs. 10.4 ± 2.2 ms). Histological and biochemical evaluation revealed myocardial oxidative stress (membrane-localized protein-4-hydroxy-trans-2-nonenal adducts) and nitrative stress (increased protein-nitrotyrosine) and varying degrees of plasma and myocardial protein-acrolein adduct formation indicative of physical translocation of ingested acrolein to the heart. Acrolein also induced myocyte hypertrophy (~2.2-fold increased myocyte area, P < 0.05), increased apoptosis (~7.5-fold), and disrupted endothelial nitric oxide synthase in the heart. DNA binding studies, immunohistochemistry, and PCR revealed significant (P < 0.05) activation of nuclear factor-κB in acrolein-exposed hearts, along with upregulated gene expression of proinflammatory cytokines tumor necrosis factor-α and interleukin-1β. Long-term oral exposure to acrolein, at an amount within the range of human unsaturated aldehyde intake, induces a phenotype of dilated cardiomyopathy in the mouse. Human exposure to acrolein may have analogous effects and raise consideration of an environmental, aldehyde-mediated basis for heart failure.

Acrolein-mediated injury in nervous system trauma and diseases

Acrolein, an α,β-unsaturated aldehyde, is a ubiquitous pollutant that is also produced endogenously through lipid peroxidation. This compound is hundreds of times more reactive than other aldehydes such as 4-hydroxynonenal, is produced at much higher concentrations, and persists in solution for much longer than better known free radicals. It has been implicated in disease states known to involve chronic oxidative stress, particularly spinal cord injury and multiple sclerosis. Acrolein may overwhelm the anti-oxidative systems of any cell by depleting glutathione reserves, preventing glutathione regeneration, and inactivating protective enzymes. On the cellular level, acrolein exposure can cause membrane damage, mitochondrial dysfunction, and myelin disruption. Such pathologies can be exacerbated by increased concentrations or duration of exposure, and can occur in normal tissue incubated with injured spinal cord, showing that acrolein can act as a diffusive agent, spreading secondary injury. Several chemical species are capable of binding and inactivating acrolein. Hydralazine in particular can reduce acrolein concentrations and inhibit acrolein-mediated pathologies in vivo. Acrolein scavenging appears to be a novel effective treatment, which is primed for rapid translation to the clinic.

Acrolein-induced dyslipidemia and acute-phase response are independent of HMG-CoA reductase

SCOPE

Aldehydes are ubiquitous natural constituents of foods, water and beverages. Dietary intake represents the greatest source of exposure to acrolein and related aldehydes. Oral acrolein induces dyslipidemia acutely and chronically increases atherosclerosis in mice, yet the mechanisms are unknown. Because lipid synthesis and trafficking are largely under hepatic control, we examined hepatic genes in murine models of acute and chronic oral acrolein exposure.

METHODS AND RESULTS

Changes in hepatic gene expression were examined using a Steroltalk microarray. Acute acrolein feeding modified plasma and hepatic proteins and increased plasma triglycerides within 15  min. By 6  h, acrolein altered hepatic gene expression including Insig1, Insig2 and Hmgcr genes and stimulated an acute-phase response (APR) with up-regulation of serum amyloid A genes (Saa) and systemic hypoalbuminemia. To test if decreased HMG-CoA reductase activity could modify acrolein-induced dyslipidemia or the APR, mice were pretreated with simvastatin. Statin treatment, however, did not alter acrolein-induced dyslipidemia or hypoalbuminemia associated with an APR. Few hepatic genes were dysregulated by chronic acrolein feeding in apoE-null mice. These studies confirmed that acute acrolein exposure altered expression of hepatic genes involved with lipid synthesis and trafficking and APR, and thus, indicated a hepatic locus of acrolein-induced dyslipidemia and APR that was independent of HMG CoA-reductase.

CONCLUSION

Dietary intake of acrolein could contribute to cardiovascular disease risk by disturbing hepatic function.

The effects of acrolein on the thioredoxin system: implications for redox-sensitive signaling

The reactive aldehyde acrolein is a ubiquitous environmental pollutant and is also generated endogenously. It is a strong electrophile and reacts rapidly with nucleophiles including thiolates. This review focuses on the effects of acrolein on thioredoxin reductase (TrxR) and thioredoxin (Trx), which are major regulators of intracellular protein thiol redox balance. Acrolein causes irreversible effects on TrxR and Trx, which are consistent with the formation of covalent adducts to selenocysteine and cysteine residues that are key to their activity. TrxR and Trx are more sensitive than some other redox-sensitive proteins, and their prolonged inhibition could disrupt a number of redox-sensitive functions in cells. Among these effects are the oxidation of peroxiredoxins and the activation of apoptosis signal regulating kinase (ASK1). ASK1 promotes MAP kinase activation, and p38 activation contributes to apoptosis and a number of other acrolein-induced stress responses. Overall, the disruption of the TrxR/Trx system by acrolein could be significant early and prolonged events that affect many aspects of redox-sensitive signaling and oxidant stress.

Acrolein induced DNA damage, mutagenicity and effect on DNA repair

Acrolein (Acr) is a ubiquitous environmental contaminant; it also can be generated endogenously by lipid peroxidation. Acr contains a carbonyl group and an olefinic double bond; it can react with many cellular molecules including amino acids, proteins and nucleic acids. In this review article we focus on updating information regarding: (i) Acr-induced DNA damage and methods of detection, (ii) repair of Acr-DNA damage, (iii) mutagenicity of Acr-DNA adducts, (iv) sequence specificity and methylation effect on Acr-DNA adduct formation and (v) the role of Acr in human cancer. We have found that Acr can inhibit DNA repair and induces mutagenic Acr-dG adducts and that the binding spectrum of Acr in the p53 gene in normal human bronchial epithelial cells is similar to the p53 mutational spectrum in lung cancer. Since Acr-DNA adduct has been identified in human lung tissue and Acr causes bladder cancer in human and rat models, we conclude that Acr is a major lung and bladder carcinogen, and its carcinogenicity arises via induction of DNA damage and inhibition of DNA repair.

Acrolein inhalation prevents vascular endothelial growth factor-induced mobilization of Flk-1+/Sca-1+ cells in mice

OBJECTIVE

Acrolein is a toxic chemical present in tobacco, wood, and coal smoke, as well as automobile exhaust. Because exposure to these pollutants is associated with an increase in cardiovascular disease risk, we studied the effects of acrolein on Flk-1(+)/Sca-1(+) cells that are involved in vascular repair.

METHODS AND RESULTS

In adult male C57BL/6 mice, inhalation of acrolein (1 part per million [ppm], 6 hours/day for 4 days or 5 ppm for 2 or 6 hours) led to the formation of protein-acrolein adducts in the bone marrow and diminished levels of plasma nitric oxide metabolites and circulating Flk-1(+)/Sca-1(+) but not Sca-1(+)-only cells. Acrolein exposure increased the number of apoptotic Flk-1(+)/Sca-1(+) cells in circulation and increased bone marrow-derived cells with endothelial characteristics (DiI-ac-low-density lipoprotein [DiI-acLDL]/UE-lectin and Flk-1(+)/Sca-1(+)) in culture. Deficits in the circulating levels of Flk-1(+)/Sca-1(+) cells were reversed after 7 days of recovery in acrolein-free air. Exposure to acrolein blocked vascular endothelial growth factor (VEGF)/AMD3100-stimulated mobilization of Flk-1(+)/Sca-1(+) but not Sca-1(+)-only cells and prevented VEGF-induced phosphorylation of Akt and endothelial nitric oxide synthase in the aorta.

CONCLUSIONS

Inhalation of acrolein increases apoptosis and suppresses the circulating levels of Flk-1(+)/Sca-1(+) cells while increasing these cells in the bone marrow and preventing their mobilization by VEGF. Exposure to acrolein-rich pollutants could impair vascular repair capacity.

Anti-acrolein treatment improves behavioral outcome and alleviates myelin damage in experimental autoimmune encephalomyelitis mouse

Oxidative stress is considered a major contributor in the pathology of multiple sclerosis (MS). Acrolein, a highly reactive aldehyde byproduct of lipid peroxidation, is thought to perpetuate oxidative stress. In this study, we aimed to determine the role of acrolein in an animal model of MS, experimental autoimmune encephalomyelitis (EAE) mice. We have demonstrated a significant elevation of acrolein protein adduct levels in EAE mouse spinal cord. Hydralazine, a known acrolein scavenger, significantly improved behavioral outcomes and lessened myelin damage in spinal cord. We postulate that acrolein is an important pathological factor and likely a novel therapeutic target in MS.

Mutagenicity and sequence specificity of acrolein-DNA adducts

Acrolein (Acr) is a major toxicant in cigarette smoke (CS); it can interact with DNA forming two major adduct isomers: alpha-OH-Acr-dG and gamma-OH-Acr-dG. Previously, we found that the Acr-DNA binding pattern in the human p53 gene coincides with the p53 mutational pattern in CS-related lung cancer; hence, we proposed that Acr is a major lung cancer etiological agent [ Feng , Z. , Hu , W. , Hu , Y. , and Tang , M.-s. ( 2006 ) Acrolein is a major cigarette-related lung cancer agent: Preferential binding at p53 mutational hotspots and inhibition of DNA repair . Proc. Natl. Acad. Sci. U.S.A. 103 , 15404 - 15409 ]. This hypothesis has been brought into question with recent work that failed to detect Acr-induced mutations in the pSP189 system [ Kim , S. I. , Pfeifer , G. P. , and Besaratinia , A. ( 2007 ) Lack of mutagenicity of acrolein-induced DNA adducts in mouse and human cells . Cancer Res. 67 , 11640 - 116472 ]. To resolve this controversy, we determined the level and the type of Acr-dG formation, and the mutagenicity of Acr-dG adducts in the same pSP189 system. We also mapped the Acr-dG adduct distribution at the nucleotide level and the Acr-dG-induced mutational spectrum in this system. We found that (1) gamma-OH-Acr-dG is the major adduct formed in Acr-modified DNA based on the LC-ESI-MS/MS analysis; (2) the mutation frequency is proportional to the extent of Acr modifications, the majority of which are G:C to T:A and G:C to A:T mutations; and (3) sequences with a run of Gs are the mutational hotspots. Using the UvrABC nuclease incision method to map the Acr-dG distribution in the supF gene sequence, we confirmed that Acr-DNA adducts preferentially form in guanine-rich sequences that are also mutational hotspots. These results reaffirm that Acr-dG adducts are mutagenic and support our hypothesis that Acr is a major etiological agent for CS and cooking fume-related lung cancer.

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 (5ppm for 6h) or sub-chronic (1ppm, 6h/day for 4days) 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.

Chitosan nanoparticle-based neuronal membrane sealing and neuroprotection following acrolein-induced cell injury

Background

The highly reactive aldehyde acrolein is a very potent endogenous toxin with a long half-life. Acrolein is produced within cells after insult, and is a central player in slow and progressive "secondary injury" cascades. Indeed, acrolein-biomolecule complexes formed by cross-linking with proteins and DNA are associated with a number of pathologies, especially central nervous system (CNS) trauma and neurodegenerative diseases. Hydralazine is capable of inhibiting or reducing acrolein-induced damage. However, since hydralazine's principle activity is to reduce blood pressure as a common anti-hypertension drug, the possible problems encountered when applied to hypotensive trauma victims have led us to explore alternative approaches. This study aims to evaluate such an alternative - a chitosan nanoparticle-based therapeutic system.

Results

Hydralazine-loaded chitosan nanoparticles were prepared using different types of polyanions and characterized for particle size, morphology, zeta potential value, and the efficiency of hydralazine entrapment and release. Hydralazine-loaded chitosan nanoparticles ranged in size from 300 nm to 350 nm in diameter, and with a tunable, or adjustable, surface charge.

Conclusions

We evaluated the utility of chitosan nanoparticles with an in-vitro model of acrolein-mediated cell injury using PC -12 cells. The particles effectively, and statistically, reduced damage to membrane integrity, secondary oxidative stress, and lipid peroxidation. This study suggests that a chitosan nanoparticle-based therapy to interfere with "secondary" injury may be possible.

Acrolein consumption induces systemic dyslipidemia and lipoprotein modification

Aldehydes such as acrolein are ubiquitous pollutants present in automobile exhaust, cigarette, wood, and coal smoke. Such aldehydes are also constituents of several food substances and are present in drinking water, irrigation canals, and effluents from manufacturing plants. Oral intake represents the most significant source of exposure to acrolein and related aldehydes. To study the effects of short-term oral exposure to acrolein on lipoprotein levels and metabolism, adult mice were gavage-fed 0.1 to 5 mg acrolein/kg bwt and changes in plasma lipoproteins were assessed. Changes in hepatic gene expression related to lipid metabolism and cytokines were examined by qRT-PCR analysis. Acrolein feeding did not affect body weight, blood urea nitrogen, plasma creatinine, electrolytes, cytokines or liver enzymes, but increased plasma cholesterol and triglycerides. Similar results were obtained with apoE-null mice. Plasma lipoproteins from acrolein-fed mice showed altered electrophoretic mobility on agarose gels. Chromatographic analysis revealed elevated VLDL cholesterol, phospholipids, and triglycerides levels with little change in LDL or HDL. NMR analysis indicated shifts from small to large VLDL and from large to medium-small LDL with no change in the size of HDL particles. Increased plasma VLDL was associated with a significant decrease in post-heparin plasma hepatic lipase activity and a decrease in hepatic expression of hepatic lipase. These observations suggest that oral exposure to acrolein could induce or exacerbate systemic dyslipidemia and thereby contribute to cardiovascular disease risk.

Acrolein scavenging: a potential novel mechanism of attenuating oxidative stress following spinal cord injury

It has long been established that oxidative stress plays a critical role in the pathophysiology of spinal cord injury, and represents an important target of therapeutic intervention following the initial trauma. However, free radical scavengers have been largely ineffective in clinical trials, and as such a novel target to attenuate oxidative stress is highly warranted. In addition to free radicals, peroxidation of lipid membranes following spinal cord injury (SCI) produces reactive aldehydes such as acrolein. Acrolein is capable of depleting endogenous antioxidants such as glutathione, generating free radicals, promoting oxidative stress, and damaging proteins and DNA. Acrolein has a significantly longer half-life than the transient free radicals, and thus may represent a potentially better target of therapeutic intervention to attenuate oxidative stress. There is growing evidence, from our lab and others, to suggest that reactive aldehydes such as acrolein play a critical role in oxidative stress and SCI. The focus of this review is to summarize the cellular and biochemical mechanisms of acrolein-induced membrane damage, mitochondrial injury, oxidative stress, cell death, and functional loss. Evidence will also be presented to suggest that acrolein scavenging may be a novel means of therapeutic intervention to attenuate oxidative stress and improve recovery following traumatic SCI.

Short term exposure to cooking fumes and pulmonary function

Background

Exposure to cooking fumes may have different deleterious effects on the respiratory system. The aim of this study was to look at possible effects from inhalation of cooking fumes on pulmonary function.

Methods

Two groups of 12 healthy volunteers (A and B) stayed in a model kitchen for two and four hours respectively, and were monitored with spirometry four times during twenty four hours, on one occasion without any exposure, and on another with exposure to controlled levels of cooking fumes.

Results

The change in spirometric values during the day with exposure to cooking fumes, were not statistically significantly different from the changes during the day without exposure, with the exception of forced expiratory time (FET). The change in FET from entering the kitchen until six hours later, was significantly prolonged between the exposed and the unexposed day with a 15.7% increase on the exposed day, compared to a 3.2% decrease during the unexposed day (p-value = 0.03). The same tendency could be seen for FET measurements done immediately after the exposure and on the next morning, but this was not statistically significant.

Conclusion

In our experimental setting, there seems to be minor short term spirometric effects, mainly affecting FET, from short term exposure to cooking fumes.

Glutathione-S-transferase P protects against endothelial dysfunction induced by exposure to tobacco smoke

Exposure to tobacco smoke impairs endothelium-dependent arterial dilation. Reactive constituents of cigarette smoke are metabolized and detoxified by glutathione-S-transferases (GSTs). Although polymorphisms in GST genes are associated with the risk of cancer in smokers, the role of these enzymes in regulating the cardiovascular effects of smoking has not been studied. The P isoform of GST (GSTP), which catalyzes the conjugation of electrophilic molecules in cigarette smoke such as acrolein, was expressed in high abundance in the mouse lung and aorta. Exposure to tobacco smoke for 3 days (5 h/day) decreased total plasma protein. These changes were exaggerated in GSTP(-/-) mice. Aortic rings isolated from tobacco smoke-exposed GSTP(-/-) mice showed greater attenuation of ACh-evoked relaxation than those from GSTP(+/+) mice. The lung, plasma, and aorta of mice exposed to tobacco smoke or acrolein (for 5 h) accumulated more acrolein-adducted proteins than those tissues of mice exposed to air, indicating that exposure to tobacco smoke results in the systemic delivery of acrolein. Relative to GSTP(+/+) mice, modification of some proteins by acrolein was increased in the aorta of GSTP(-/-) mice. Aortic rings prepared from GSTP(-/-) mice that inhaled acrolein (1 ppm, 5 h/day for 3 days) or those exposed to acrolein in an organ bath showed diminished ACh-induced arterial relaxation more strongly than GSTP(+/+) mice. Acrolein-induced endothelial dysfunction was prevented by pretreatment of the aorta with N-acetylcysteine. These results indicate that GSTP protects against the endothelial dysfunction induced by tobacco smoke exposure and that this protection may be related to the detoxification of acrolein or other related cigarette smoke constituents.

The effects of acrolein on peroxiredoxins, thioredoxins, and thioredoxin reductase in human bronchial epithelial cells

Inhalation is a common form of exposure to acrolein, a toxic reactive volatile aldehyde that is a ubiquitous environmental pollutant. Bronchial epithelial cells would be directly exposed to inhaled acrolein. The thioredoxin (Trx) system is essential for the maintenance of cellular thiol redox balance, and is critical for cell survival. Normally, thioredoxin reductase (TrxR) maintains the cytosolic (Trx1) and mitochondrial (Trx2) thioredoxins in the reduced state, and the thioredoxins keep the peroxiredoxins (Prx) reduced, thereby supporting their peroxidase function. The effects of acrolein on TrxR, Trx and Prx in human bronchial epithelial (BEAS-2B) cells were determined. A 30-min exposure to 5 microM acrolein oxidized both Trx1 and Trx2, although significant effects were noted for Trx1 at even lower acrolein concentrations. The effects on Trx1 and Trx2 could not be reversed by treatment with disulfide reductants. TrxR activity was inhibited 60% and >85% by 2.5 and 5 microM acrolein, respectively. The endogenous electron donor for TrxR, NADPH, could not restore its activity, and activity did not recover in cells during a 4-h acrolein-free period in complete medium. The effects of acrolein on TrxR and Trx therefore extend beyond the duration of exposure. While there was a strong correlation between TrxR inhibition and Trx1 oxidation, the irreversible effects on Trx1 suggest direct effects of acrolein rather than loss of reducing equivalents from TrxR. Trx2 did not become oxidized until > or = 90% of TrxR was inhibited, but irreversible effects on Trx2 also suggest direct effects of acrolein. Prx1 (cytosolic) and Prx3 (mitochondrial) shifted to a largely oxidized state only when >90 and 100% of their respective Trxs were oxidized. Prx oxidation was readily reversed with a disulfide reductant, suggesting that Prx oxidation resulted from lack of reducing equivalents from Trx and not direct reaction with acrolein. The effects of acrolein on the thioredoxin system and peroxiredoxins could have important implications for cell survival, redox-sensitive cell signaling, and tolerance to other oxidant insults.

Role of endoplasmic reticulum stress in acrolein-induced endothelial activation

Acrolein is a ubiquitous environmental pollutant and an endogenous product of lipid peroxidation. It is also generated during the metabolism of several drugs and amino acids. In this study, we examined the effects of acrolein on endothelial cells. Treatment of human umbilical vein endothelial cells (HUVECs) with 2 to 10 microM acrolein led to an increase in the phosphorylation of eIF-2alpha within 10 to 30 min of exposure. This was followed by alternate splicing of XBP-1 mRNA and an increase in the expression of the endoplasmic reticulum (ER) chaperone genes Grp78 and Herp. Within 2-4 h of treatment, acrolein also increased the abundance and the nuclear transport of the transcription factors ATF3, AFT4, and CHOP. Acrolein-induced increase in ATF3 was prevented by treating the cells with the chemical chaperone - phenylbutyric acid (PBA). Treatment with acrolein increased phosphorylation of ERK1/2, p38, and JNK. The increase in JNK phosphorylation was prevented by PBA. Acrolein treatment led to activation and nuclear translocation of the transcription factor NF-kappaB and an increase in TNF-alpha, IL-6 and IL-8, but not MCP-1, mRNA. Increased expression of cytokine genes and NF-kappaB activation were not observed in cells treated with PBA. These findings suggest that exposure to acrolein induces ER stress and triggers the unfolded protein response and that NF-kappaB activation and stimulation of cytokine production by acrolein could be attributed, in part, to ER stress. Chemical chaperones of protein-folding may be useful in treating toxicological and pathological states associated with excessive acrolein exposure or production.

Diurnal cycles of acrolein and other small aldehydes in regions impacted by vehicle emissions

This research determined the diurnal and seasonal differences in the ambient atmospheric concentrations of acrolein and several small aldehydes and attempted to link the chemicals to their potential sources. Two summertime and two wintertime sampling episodes were conducted in Roseville, CA at a site located near several busy roadways. One additional sampling episode was conducted at a remote site in the summer to estimate regional background concentrations of aldehydes. Each sampling episode consisted of duplicate samples collected every two hours around the clock for three days. Acrolein concentrations did not correlate with traffic density, ozone concentrations, or tracers of direct vehicle emissions, which argues against vehicles being a dominant source of ambient acrolein through primary emissions or secondary oxidation products. The results showed that wintertime acrolein concentrations correlated well with 2-furaldehyde, which is a tracer of biomass burning, thus suggesting that wood smoke is an important source of ambient acrolein. Other regularly detected carbonyls were tentatively assigned to different source classes (direct vehicle emissions, photochemical oxidation, wood smoke or transport from the Sierra Nevada Mountains) based on time series patterns and correlations with indicators of potential sources (e.g., ozone, traffic density, etc.).

Critical role of acrolein in secondary injury following ex vivo spinal cord trauma

The pathophysiology of spinal cord injury (SCI) is characterized by the initial, primary injury followed by secondary injury processes in which oxidative stress is a critical component. Secondary injury processes not only exacerbate pathology at the site of primary injury, but also result in spreading of injuries to the adjacent, otherwise healthy tissue. The lipid peroxidation byproduct acrolein has been implicated as one potential mediator of secondary injury. To further and rigorously elucidate the role of acrolein in secondary injury, a unique ex vivo model is utilized to isolate the detrimental effects of mechanical injury from toxins such as acrolein that are produced endogenously following SCI. We demonstrate that (i) acrolein-Lys adducts are capable of diffusing from compressed tissue to adjacent, otherwise uninjured tissue; (ii) secondary injury by itself produces significant membrane damage and increased superoxide production; and (iii) these injuries are significantly attenuated by the acrolein scavenger hydralazine. Furthermore, hydralazine treatment results in significantly less membrane damage 2 h following compression injury, but not immediately after. These findings support our hypothesis that, following SCI, acrolein is increased to pathologic concentrations, contributes significantly to secondary injury, and thus represents a novel target for scavenging to promote improved recovery.

A comparative 90-day toxicity study of allyl acetate, allyl alcohol and acrolein

Allyl acetate (AAC), allyl alcohol (AAL), and acrolein (ACR) are used in the manufacture of detergents, plastics, pharmaceuticals, and chemicals and as agricultural agents. A metabolic relationship exists between these chemicals in which allyl acetate is metabolized to allyl alcohol and subsequently to the highly reactive, alpha,beta-unsaturated aldehyde, acrolein. Due to the weaker reactivity of the protoxicants, allyl acetate and allyl alcohol, relative to acrolien we hypothesized the protoxicants would attain greater systemic exposure and therefore deliver higher doses of acrolein to the internal organs. By extension, the higher systemic exposure to acrolein we hypothesized should lead to more internal organ toxicity in the allyl acetate and allyl alcohol treated animals relative to those treated with acrolein. To address our hypothesis we compared the range of toxicities produced by all three chemicals in male and female Fischer 344/N rats and B6C3F1 mice exposed 5 days a week for 3 months by gavage in 0.5% methylcellulose. Rats (10/group) were dosed with 0-100mg/kg allyl acetate, 0-25mg/kg allyl alcohol, or 0-10mg/kg acrolein. Mice (10/group) were dosed with 0-125mg/kg allyl acetate, 0-50mg/kg allyl alcohol, or 0-20mg/kg acrolein. The highest dose of allyl acetate and acrolein decreased survival in both mice and rats. The primary target organ for the toxicity of all three chemicals in both species and sexes was the forestomach; squamous epithelial hyperplasia was observed following exposure to each chemical. In both species the highest allyl acetate dose group exhibited forestomach epithelium necrosis and hemorrhage and the highest dose of acrolein led to glandular stomach hemorrhage. Liver histopathology was the most apparent with allyl acetate, was also observed with allyl alcohol, but was not observed with acrolein. All chemicals had effects on the hematopoietic system with allyl acetate having the most pronounced effect. When dosed at quantities limited by toxicity, allyl acetate and allyl alcohol produce higher levels of urinary mercapturic acids than the minimally toxic dose of acrolein. This observation is likely due to biotransformation of allyl acetate and ally alcohol to acrolein that occurs after absorption and suggests that these chemicals are protoxicants that increase systemic exposure of acrolein. Increased systemic exposure to acrolein is likely responsible for the differences in hepatic toxicological profile observed with these chemicals.

Acrolein consumption exacerbates myocardial ischemic injury and blocks nitric oxide-induced PKCepsilon signaling and cardioprotection

Aldehydes are common reactive constituents of food, water and air. Several food aldehydes are potentially carcinogenic and toxic; however, the direct effects of dietary aldehydes on cardiac ischemia-reperfusion (IR) injury are unknown. We tested the hypothesis that dietary consumption of aldehydes modulates myocardial IR injury and preconditioning. Mice were gavage-fed the alpha, beta-unsaturated aldehyde acrolein (5mg/kg) or water (vehicle) 24h prior to a 30-min coronary artery occlusion and 24-hour reperfusion. Myocardial infarct size was significantly increased in acrolein-treated mice, demonstrating that acute acrolein exposure worsens cardiac IR injury. Furthermore, late cardioprotection afforded by the nitric oxide (NO) donor diethylenetriamine/NO (DETA/NO; dose: 0.1mg/kg x 4, i.v.) was abrogated by the administration of acrolein 2h prior to DETA/NO treatment, indicating that oral acrolein impairs NO donor-induced late preconditioning. To examine potential intracellular targets of aldehydes, we investigated the impact of acrolein on mitochondrial PKCepsilon signaling in the heart. Acrolein-protein adducts were formed in a dose-dependent manner in isolated cardiac mitochondria in vitro and specific acrolein-PKCepsilon adducts were present in cardiac mitochondrial fractions following acrolein exposure in vivo, demonstrating that mitochondria are major targets of aldehyde toxicity. Furthermore, DETA/NO preconditioning induced both PKCepsilon translocation and increased mitochondrial PKCepsilon localization. Both of these responses were blocked by acrolein pretreatment, providing evidence that aldehydes disrupt cardioprotective signaling events involving PKCepsilon. Consumption of an aldehyde-rich diet could exacerbate cardiac IR injury and block NO donor-induced cardioprotection via mechanisms that disrupt PKCepsilon signaling.

Characterization of acrolein-induced protein cross-links

Lipid peroxidation products contribute to protein aggregation that occurs during oxidative stress in a number of degenerative disorders. Acrolein (ACR), a highly toxic lipid peroxidation aldehyde, is a strong cross-linking agent of cellular components such as proteins. To understand the mechanisms of oxidative stress-induced protein aggregation, this study characterized the ACR modification of chain B from bovine insulin by mass spectrometry. To identify the cross-linking sites, the ACR-treated peptide was digested with a protease and the resulting peptides were analysed by liquid chromatography-tandem mass spectrometry. Inter- and intra-molecular cross-linking adducts were identified between amino groups and the side chain of histidine in the peptide. These results indicated that the ACR-induced cross-links were accompanied by two reactions, namely Michael addition and Schiff base formation. In conclusion, the use of mass spectrometric techniques provided chemical evidence for protein cross-linking with ACR.

Studies on the toxicity of acetone, acrolein and carbon dioxide on stored-product insects and wheat seed

In laboratory experiments toxicity of acetone, acrolein and carbon dioxide were investigated against 4 species of stored-product insects. In all experiments, acrolein was the most toxic compound to the tested insects. In empty-space trials, estimated LD50 values of acrolein for adults of Tribolium castaneum (Herbst) (Tenebrionidae), Rhizopertha dominica (F.) (Bostrychidae), Sitophilus oryzae L. (Curculionidae) and Oryzaephilus surinamensis L. (Silvanidae) were 7.26, 6.09, 6.37 and 5.65 microl L(-1), respectively. Penetration tests revealed that acetone and acrolein vapors could penetrate into the wheat mass and kill concealed insects in interkernel spaces. Comparison of LD50 values of acrolein between empty-space tests and penetration experiments indicated that the increase in penetration toxicity was 4.96, 4.54, 3.64 and 3.43-fold for T. castaneum, R. dominica, S. oryzae and O. surinamensis, respectively. The effect of carbon dioxide on the toxicity of acrolein and acetone was synergistic. In the hidden infestation trials, the acrolein vapors destroyed the developmental stages of S. oryzae concealed inside the wheat kernels and resulted in a complete control with concentration of 80 microl L(-1) for 24 h and subsequently observed during 8 weeks after the exposure. Wheat germination and plumule length was reduced following exposure to all doses of acrolein. Acetone and carbon dioxide were harmless to wheat seed viability. The mixture of carbon dioxide with acrolein can be considered as a potential fumigant for replacing methyl bromide or phosphine under ambient storage conditions specifically in empty-space fumigations.

ThermoTRP channels in nociceptors: taking a lead from capsaicin receptor TRPV1

Nociceptors with peripheral and central projections express temperature sensitive transient receptor potential (TRP) ion channels, also called thermoTRP's. Chemosensitivity of thermoTRP's to certain natural compounds eliciting pain or exhibiting thermal properties has proven to be a good tool in characterizing these receptors. Capsaicin, a pungent chemical in hot peppers, has assisted in the cloning of the first thermoTRP, TRPV1. This discovery initiated the search for other receptors encoding the response to a wide range of temperatures encountered by the body. Of these, TRPV1 and TRPV2 encode unique modalities of thermal pain when exposed to noxious heat. The ability of TRPA1 to encode noxious cold is presently being debated. The role of TRPV1 in peripheral inflammatory pain and central sensitization during chronic pain is well known. In addition to endogenous agonists, a wide variety of chemical agonists and antagonists have been discovered to activate and inhibit TRPV1. Efforts are underway to determine conditions under which agonist-mediated desensitization of TRPV1 or inhibition by antagonists can produce analgesia. Also, identification of specific second messenger molecules that regulate phosphorylation of TRPV1 has been the focus of intense research, to exploit a broader approach to pain treatment. The search for a role of TRPV2 in pain remains dormant due to the lack of suitable experimental models. However, progress into TRPA1's role in pain has received much attention recently. Another thermoTRP, TRPM8, encoding for the cool sensation and also expressed in nociceptors, has recently been shown to reduce pain via a central mechanism, thus opening a novel strategy for achieving analgesia. The role of other thermoTRP's (TRPV3 and TRPV4) encoding for detection of warm temperatures and expressed in nociceptors cannot be excluded. This review will discuss current knowledge on the role of nociceptor thermoTRPs in pain and therapy and describes the activator and inhibitor molecules known to interact with them and modulate their activity.

Lack of mutagenicity of acrolein-induced DNA adducts in mouse and human cells

Acrolein is an endogenous metabolite and a ubiquitous environmental pollutant. Recently, it has been suggested that acrolein is a major etiologic agent for tobacco smoking-related lung cancer. Despite the known DNA-damaging effects of acrolein, its mutagenicity to mammalian cells remains uncertain. We have investigated acrolein-induced DNA damage in relation to mutagenesis, with special focus on DNA repair, in mouse and human cells. We mapped the formation of acrolein-induced DNA adducts and the kinetics of repair of the induced lesions in the cII transgene, the mutational target, in acrolein-treated transgenic mouse fibroblasts. Acrolein-DNA adducts were formed preferentially at specific nucleotide positions, mainly at G:C base pairs, along the cII transgene. The induced acrolein-DNA adducts were moderately resistant to DNA repair. Quantification of cII mutant frequency in acrolein-treated cells, however, revealed that acrolein was not mutagenic to these cells at doses sufficient to produce DNA adducts. Determination of supF mutant frequency in DNA repair-proficient and DNA repair-deficient human fibroblasts transfected with acrolein-treated plasmids confirmed a lack of acrolein mutagenicity. Because CpG methylation may intensify acrolein-DNA adduction, we examined whether the extent of CpG methylation in the supF gene can determine acrolein-induced mutagenesis in human cells. Enhancement of acrolein-DNA adduction by methylating CpGs in the supF sequence did not elicit a mutagenic response in human fibroblasts, however. We conclude that acrolein is not mutagenic to mouse and human fibroblasts, regardless of DNA repair capacity or methylation status of CpGs, possibly because of a highly accurate replication bypass of the induced lesions.

Molecular mechanisms of the conjugated alpha,beta-unsaturated carbonyl derivatives: relevance to neurotoxicity and neurodegenerative diseases

Conjugated alpha,beta-unsaturated carbonyl derivatives such acrylamide, acrolein, and 4-hydroxy-2-nonenal (HNE) are members of a large class of chemicals known as the type-2 alkenes. Human exposure through diet, occupation, and pollution is pervasive and has been linked to toxicity in most major organs. Evidence suggests that these soft electrophiles produce toxicity by a common mechanism involving the formation of Michael-type adducts with nucleophilic sulfhydryl groups. In this commentary, the adduct chemistry of the alpha,beta-unsaturated carbonyls and possible protein targets will be reviewed. We also consider how differences in electrophilic reactivity among the type-2 alkenes impact corresponding toxicokinetics and toxicological expression. Whereas these concepts have mechanistic implications for the general toxicity of type-2 alkenes, this commentary will focus on the ability of these chemicals to produce presynaptic damage via protein adduct formation. Given the ubiquitous environmental presence of the conjugated alkenes, discussions of molecular mechanisms and possible neurotoxicological risks could be important. Understanding the neurotoxicodynamic of the type-2 alkenes might also provide mechanistic insight into neurodegenerative conditions where neuronal oxidative stress and presynaptic dysfunction are presumed initiating events. This is particularly germane to a recent proposal that lipid peroxidation and the subsequent liberation of acrolein and HNE in oxidatively stressed neurons mediate synaptotoxicity in brains of Alzheimer's disease patients. This endogenous neuropathogenic process could be accelerated by environmental type-2 alkene exposure because common nerve terminal proteins are targeted by alpha,beta-unsaturated carbonyl derivatives. Thus, the protein adduct chemistry of the conjugated type-2 alkenes offers a mechanistic explanation for the environmental toxicity induced by these chemicals and might provide insight into the pathogenesis of certain human neurodegenerative diseases.

Hydralazine inhibits compression and acrolein-mediated injuries in ex vivo spinal cord

We have previously shown that acrolein, a lipid peroxidation byproduct, is significantly increased following spinal cord injury in vivo, and that exposure to neuronal cells results in oxidative stress, mitochondrial dysfunction, increased membrane permeability, impaired axonal conductivity, and eventually cell death. Acrolein thus may be a key player in the pathogenesis of spinal cord injury, where lipid peroxidation is known to be involved. The current study demonstrates that the acrolein scavenger hydralazine protects against not only acrolein-mediated injury, but also compression in guinea pig spinal cord ex vivo. Specifically, hydralazine (500 mumol/L to 1 mmol/L) can significantly alleviate acrolein (100-500 mumol/L)-induced superoxide production, glutathione depletion, mitochondrial dysfunction, loss of membrane integrity, and reduced compound action potential conduction. Additionally, 500 mumol/L hydralazine significantly attenuated compression-mediated membrane disruptions at 2 and 3 h following injury. This was consistent with our findings that acrolein-lys adducts were increased following compression injury ex vivo, an effect that was prevented by hydralazine treatment. These findings provide further evidence for the role of acrolein in spinal cord injury, and suggest that acrolein-scavenging drugs such as hydralazine may represent a novel therapy to effectively reduce oxidative stress in disorders such as spinal cord injury and neurodegenerative diseases, where oxidative stress is known to play a role.

Measurements of OVOCs and NMHCs in a Swiss highway tunnel for estimation of road transport emissions

Eighteen oxygenated volatile organic compounds (OVOCs) and eight nonmethane hydrocarbons (NMHCs) were measured continuously during a two-week campaign in 2004 in the Gubrist highway tunnel (Switzerland). The study aimed to estimate selected OVOC and NMHC emissions of the current vehicle fleet under highway conditions. For the measured OVOCs the highest EFs were found for ethanol (9.7 mg/km), isopropanol (3.2 mg/km), and acetaldehyde (2.5 mg/km), followed by acetone, benzaldehyde, and acrolein. Formaldehyde, the most abundant OVOC measured in other studies, was not measured by the method applied. Relative emissions of the measured OVOCs were estimated to contribute approximately 6 and 4% to the total road traffic VOC emissions from Switzerland and Europe, respectively. Results are compared with those from previous studies from the same tunnel performed in 1993 and 2002, and from campaigns in other tunnels. A continuous reduction in the emission factors (EFs) was determined for all measured compounds from 1993 until 2004. The relative contributions of light-duty vehicles (LDV) and heavy-duty vehicles (HDV) to the total emissions indicated that OVOCs were mainly produced by the HDVs, whereas LDVs dominated the production of the NMHCs.

Mechanisms of acrolein-induced myocardial dysfunction: implications for environmental and endogenous aldehyde exposure

Aldehydes are ubiquitous pollutants generated during the combustion of organic materials and are present in air, water, and food. Several aldehydes are also endogenous products of lipid peroxidation and by-products of drug metabolism. Despite well-documented high reactivity of unsaturated aldehydes, little is known regarding their cardiovascular effects and their role in cardiac pathology. Accordingly, we examined the myocardial effects of the model unsaturated aldehyde acrolein. In closed-chest mice, intravenous acrolein (0.5 mg/kg) induced rapid but reversible left ventricular dilatation and dysfunction. In mouse myocytes, micromolar acrolein acutely depressed myofilament Ca(2+) responsiveness without altering catecholamine sensitivity, similar to the phenotype of stunned myocardium. Immunoblotting revealed increased acrolein-protein adducts and protein-carbonyls in both acrolein-exposed myocardium (1.8-fold increase, P < 0.002) and myocytes (6.4-fold increase, P < 0.02). Both the contractile dysfunction and adduct formation were markedly attenuated by pretreatment with the thiol donor N-acetylcysteine (5 mM). Two-dimensional gel electrophoresis and mass-assisted laser desorption/ionization time-of-flight mass spectrometry analysis revealed two groups of adducted proteins, sarcomeric/cytoskeletal proteins (cardiac alpha-actin, desmin, myosin light polypeptide 3) and energy metabolism proteins (mitochondrial creatine kinase-2, ATP synthase), indicating site-specific protein modification that was confirmed by immunohistochemical colocalization. We conclude that direct exposure to acrolein induces selective myofilament impairment, which may be, in part, related to the modification of proteins involved in myocardial contraction and energy metabolism. Myocardial dysfunction induced by acrolein and related aldehydes may be symptomatic of toxicological states associated with ambient or occupational exposures or drug toxicity. Moreover, aldehydes such as acrolein may mediate cardiac dysfunction in pathologies characterized by high-oxidative stress.

Ovicidal activity of acrolein vapors to Indian meal moth eggs of various ages

The effect of acrolein vapors against carefully aged eggs of Indian meal moth at 27 +/- 1 and 17 +/- 1 degrees C at different dosage levels of acrolein over various exposure times was determined. Considerable variation in the susceptibility of different age groups of eggs was apparent in the fiducial limits of the LD50 values. At both temperatures and 24 h exposure period, eggs aged 1-2 day-old were more tolerant to acrolein than other age groups. In all bioassays, eggs exposed to higher dosages of acrolein developed at smaller rate. This was significant for the eggs, which were exposed to the highest dosage for 24 h. Increasing the temperature from 17 +/- 1 to 27 +/- 1 degrees C greatly increased the efficacy of acrolein. Overall, at 27 +/- 1 degrees C eggs of P. interpunctella were killed by less than one-fourth of the dosage required for control at 17 +/- 1 degrees C. Acrolein achieved 50% mortality with a dosage of 3.80 mg L(-1) in 1-2 day-old eggs at 27 +/- 1 degrees C. At this temperature hatching was retarded and greatly reduced when eggs aged 1-2 day-old were exposed to 32 mg L(-1) of acrolein for the 24 h exposure period. There was no evidence of a hatch delay longer than the time spent under vapors for eggs exposed at 17 +/- 1 or 27 +/- 1 degrees C, indicating that some development must have occurred under fumigation.

Acrolein inactivates paraoxonase 1: changes in free acrolein levels after hemodialysis correlate with increases in paraoxonase 1 activity in chronic renal failure patients

BACKGROUND

Acrolein is a very reactive aldehyde present in cigarette smoke and endogenously generated by pathways such as lipid peroxidation and threonine metabolism by phagocytes. Acrolein has been shown to affect uptake of cholesterol by HDL. We hypothesized that acrolein could also have deleterious effects on paraoxonase 1 (PON-1) activity. We also determined whether free serum acrolein levels are higher in renal failure, and assessed whether they decrease after hemodialysis (HD) and whether this change correlates with increases in PON-1 activity.

METHODS

We incubated human HDL with 0-10 mmol/l acrolein for 2 h and measured PON-1 activity and structural changes. Acrolein was also measured in 40 end stage renal disease (ESRD) patients (before and after a hemodialysis session), and 40 control subjects.

RESULTS

We found that acrolein inhibits PON-1 activity in HDL in a time and concentration dependent fashion. Inhibition occurred at 40% at 0.5 mmol/l and was cancelled by cysteine but not by aminoguanidine or carnosine. We confirm that free serum acrolein levels are higher in chronic renal failure patients and demonstrate that they are partially removed by HD. Decrease in acrolein levels after dialysis correlate with increases in PON-1 activity (r=0.32, p 0.01).

CONCLUSION

Acrolein inactivates paraoxonase 1 in HDL, a process that is inhibited by N-acetylcysteine. We confirm that acrolein levels are higher in ESRD and show for the first time, data supporting that acrolein is partially removed by hemodialysis. Decrease in acrolein levels after dialysis correlates with increase in PON-1 activity. This could offer new insights to explain low PON-1 activities in smokers and renal failure subjects as well as pointing at thiol-conserving reducing compounds such as N-acetylcysteine, as putative therapeutic palliatives.

Fumigant action of acrolein on insects and seed viability

In laboratory experiments toxicity of acrolein vapors was investigated against 4 species of stored-product insects. In empty-space trials, estimated of the median lethal dosages of acrolein against adults of Oryzaephilus surinamensis (L.), Sitophilus oryzae (L.), Rhyzopertha dominica (F.) and Tribolium castaneum (Herbst), were 1.87, 2.35, 3.12 and 6.65 mg L(-1), respectively. Penetration tests revealed that acrolein vapors could penetrate into the wheat mass and kill concealed insects in interkernel spaces. Comparison of LC50 values between empty-space tests and penetration experiments after 24 h exposure indicated that the increase in penetration toxicity was 6.34, 6.31, 7.17 and 4.54-fold for O. surinamensis, S. oryzae, R. dominica and T. castaneum, respectively. In the hidden infestation trials, the acrolein vapors destroyed all the developmental stages of S. oryzae and R. dominica concealed inside the wheat kernels, resulted in a complete control with dosage of 80 mg L(-1) for 24 h and subsequently observed during 8 weeks after the exposure. Wheat germination rate was diminished by fumigation with acrolein. The plumule length was reduced following exposure to all dosages of acrolein. It is concluded that acrolein could be considered as a potential compound for empty-space fumigations.