Acrolein-an α,ß-Unsaturated Aldehyde: A Review of Oral Cavity Exposure and Oral Pathology Effects.

Acrolein is a highly reactive unsaturated aldehyde widely present in the environment, particularly as a product of tobacco smoke. Our previous studies indicated the adverse consequences of even short-term acrolein exposure and proposed a molecular mechanism of its potential harmful effect on oral cavity keratinocytic cells. In this paper we chose to review the broad spectrum of acrolein sources such as pollution, food, and smoking. Consequently, in this paper we consider a high level of oral exposure to acrolein through these sources and discuss the noxious effects it has on the oral cavity including on salivary quality and contents, oral resistance to oxidative stress, and stress mechanism activation in a variety of oral cells.

The Stress Reaction: A Historical Perspective.

The history of stress research - milestones and people. Definitions and modern concepts of stress as well as the conflict between Hans Selye and the psychologists are described in this review. The molecular and physiological mechanisms of stress and their possible pharmacological intervention are introduced. The cycle of stress is presented as a new concept of the stress reaction, trying to bridge the gap between physiology and psychology. The cycle is a circular event in life, composed of 4 phases: (1) the resting ground phase, (2) the tension phase, (3) the response phase, and (4) the relief phase. In each phase, both physiological and psychological components can be assessed. These components are the basis for the proper handling of each phase and provide a unified model for the psycho-biological response to stress. In addition, parameters of the cycle such as frequency, duration, and intensity can be measured, providing an effective tool for stress management. Finally, modern techniques and mechanisms for coping with stress are discussed like the Norwegian Gate Theory and Lazarus Dichotomy Model for the Stress Reaction. In the above models, specific examples of how people respond to the first time encounter of stressful events and how soldiers cope with stress are presented.

The role of E3 ubiquitin-ligases MuRF-1 and MAFbx in loss of skeletal muscle mass.

The ubiquitin-proteasome system (UPS) is the main regulatory mechanism of protein degradation in skeletal muscle. The ubiquitin-ligase enzymes (E3s) have a central role in determining the selectivity and specificity of the UPS. Since their identification in 2001, the muscle specific E3s, muscle RING finger-1 (MuRF-1) and muscle atrophy F-box (MAFbx), have been shown to be implicated in the regulation of skeletal muscle atrophy in various pathological and physiological conditions. This review aims to explore the involvement of MuRF-1 and MAFbx in catabolism of skeletal muscle during various pathologies, such as cancer cachexia, sarcopenia of aging, chronic kidney disease (CKD), diabetes, and chronic obstructive pulmonary disease (COPD). In addition, the effects of various lifestyle and modifiable factors (e.g. nutrition, exercise, cigarette smoking, and alcohol) on MuRF-1 and MAFbx regulation will be discussed. Finally, evidence of potential strategies to protect against skeletal muscle wasting through inhibition of MuRF-1 and MAFbx expression will be explored.

Are E-cigarettes a safe and good alternative to cigarette smoking?

Electronic cigarettes (E-cigarettes) are devices that can vaporize a nicotine solution combined with liquid flavors instead of burning tobacco leaves. Since their emergence in 2004, E-cigarettes have become widely available, and their use has increased exponentially worldwide. E-cigarettes are aggressively advertised as a smoking cessation aid; as healthier, cheaper, and more socially acceptable than conventional cigarettes. In recent years, these claims have been evaluated in numerous studies. This review explores the development of the current E-cigarette and its market, prevalence of awareness, and use. The review also explores the beneficial and adverse effects of E-cigarettes in various aspects in accordance with recent research. The discussed aspects include smoking cessation or reduction and the health risks, social impact, and environmental consequences of E-cigarettes.

Smoking cessation-related weight gain--beneficial effects on muscle mass, strength and bone health.

AIMS: To examine the effects of smoking cessation on body composition and muscle strength in comparison with continued smoking. DESIGN AND SETTING: Twelve-month longitudinal study of adult smokers conducted in Haifa, Israel. PARTICIPANTS: Eighty-one smokers recruited from a smoking cessation programme combining group counselling and varenicline treatment. MEASUREMENTS: Measurements were taken at the beginning of the programme and after 12 months. Body composition was assessed by dual-energy X-ray absorptiometry. Muscle strength was measured by handgrip dynamometry and predicted one-repetition maximum tests. Dietary intake and physical activity levels were estimated using questionnaires. Smoking status was determined by urine cotinine. The effect of smoking cessation was assessed using univariate and multivariable linear regression analyses. FINDINGS: Forty-one participants (age 44 ± 12 years) completed all baseline and follow-up measurements (76% continued smokers; 24% quitters). All measures of body composition and muscle strength were increased among quitters when compared with continued smokers. Adjusted differences [95% confidence interval (CI)] between quitters and smokers were: body weight 4.43 kg (1.56-7.31 kg); lean mass 1.26 kg (0.24-2.28 kg); fat mass 3.15 kg (0.91-5.39 kg); bone mineral content 48.76 g (12.06-85.54 g); bone mineral density 0.024 g/cm(2) (0.004-0.043 g/cm(2) ); handgrip strength 3.6 kg (1.12-6.08 kg); predicted one-repetition maximum of chest press 7.85 kg (1.93-13.76 kg); and predicted one-repetition maximum of leg press 17.02 kg (7.29-26.75 kg). CONCLUSIONS: Smoking cessation is associated with weight gain mainly through accumulating extra fat, but is also associated with increased muscle mass, muscle strength and bone density.

Oxidative stress in the oral cavity: sources and pathological outcomes.

Oxidative stress (OS), an imbalance in the oxidant-antioxidant equilibrium, is thought to be involved in the development of many seemingly unrelated diseases. Oral cavity tissues are a unique environment constantly exposed to internal and external compounds and material hazards as almost no other part of the human body. Some of the compounds are capable of generating OS. Here, the main groups of endogenous as well as exogenous OS sources are presented, followed by their oxidative effect on the salivary contents and function. The oxidative mechanisms in oral cells and their pathologic influence are also discussed.

Enhanced cardiovascular risk and altered oxidative status in elders with moderate excessive body fat.

Aging and obesity are linked to oxidative stress. Oxidative stress may mediate age-related cardiovascular diseases. Although the body mass index (kg/m2) defines obesity (≥30) and overweight (25-29.9), it may fail to detect crucial differences in body fat content in elders. Consequently, we measured body fatness in 42 healthy elders and evaluated their cardiovascular risk factors and the extent of their physical activity. We assessed plasma, erythrocytes, and saliva oxidative stress biomarkers in this population. A higher fat mass was associated with a less active lifestyle, more metabolic syndrome components, an enhanced Framingham 10-year risk score, and augmented insulin resistance. Individuals with excessive body fat had significantly less oral peroxidase enzymes activity than those with normal body fat. Erythrocyte susceptibility to oxidative hemolysis, previously reported to be elevated with physical activity, was marginally lower in the higher fat group. Other biomarkers of oxidative stress in saliva, plasma, and erythrocytes were similar in both groups. A 6% elevation in body fat with a less active lifestyle and an increased cardiovascular risk is associated with a decline in salivary anti-oxidative activity. Such reduced activity may contribute to deteriorating oral health in obese elders. Thus, this study provides novel information on the contribution of excessive body fat to oxidative status and cardiovascular risk in old age.

Oxidative damage in keratinocytes exposed to cigarette smoke and aldehydes.

Cigarette smoke (CS) is a significant environmental source of human exposure to chemically active saturated (acetaldehyde) and α,ß-unsaturated aldehydes (acrolein) inducing protein carbonylation and dysfunction. The exposure of oral tissues to environmental hazards is immense, especially in smokers. The objectives of the current study were to examine the effect of aldehydes originating from CS on intracellular proteins of oral keratinocytes and to observe the antioxidant response in these cells. Intracellular protein carbonyl modification under CS, acrolein and acetaldehyde exposure in the HaCaT keratinocyte cell line, representing oral keratinocytes was examined by Western blot. Possible intracellular enzymatic dysfunction under the above conditions was examined by lactate dehydrogenase (LDH) activity assay. Oxidative stress response was investigated, by DCF (2,7-dichlorodihydrofluorescein) assay and GSH (glutathione) oxidation. Intracellular protein carbonyls increased 5.2 times after CS exposure and 2.7 times after exposure to 1 µmol of acrolein. DCF assay revealed an increase of fluorescence intensity 3.2 and 3.1 times after CS and acrolein exposure, respectively. CS caused a 72.5% decrease in intracellular GSH levels compared to controls. Activity of intracellular LDH was preserved. α,ß-Unsaturated aldehydes from CS are capable of intracellular protein carbonylation and have a role in intracellular oxidative stress elevation in keratinocytes, probably due to the reduction in GSH levels.

LDH enzyme activity in human saliva: the effect of exposure to cigarette smoke and its different components.

OBJECTIVE: Aldehydes and reactive nitrogen species (RNS) are important chemically active agents in cigarette smoke (CS). Salivary lactate dehydrogenase (LDH) originates predominantly from oral epithelium and was identified as an oral state marker. Its activity in saliva decreases after CS exposure. The aims of the current study were to identify the specific damaging agents in CS responsible for this activity reduction and to understand the mechanisms participating in CS oxidative damage to the salivary enzymes. METHODS: Purified and salivary LDH samples were exposed to different levels of CS, pure acrolein, acetaldehyde, peroxynitrite and RNS donors. Each response of the isolated agent to the exposure was examined by a spectrophotometric enzyme activity assay and a Western blot. RESULTS: CS exposure caused a 34% reduction in LDH activity. Isolated treatment with unsaturated-aldehydes (acrolein, 10µmol) caused a 61% reduction, while saturated-aldehydes (acetaldehyde, 200µmol), peroxynitrite (200µM) and RNS donor (SIN-1, 2mM) caused no substantial effect. All five LDH isoenzymes reacted similarly. The carbonyl immunoblotting assay revealed a fourfold increase in carbonyl content when treated with CS and a sevenfold increase when treated with acrolein. CONCLUSION: α,ß-Unsaturated-aldehydes were identified as the main CS ingredient responsible for salivary LDH activity diminution. The effect of saturated-aldehydes and RNS donors was negligible. Unsaturated-aldehydes are capable of introducing carbonyl group into proteins, causing their dysfunction. This provides a molecular explanation for a decrease in LDH enzymatic activity in saliva.

Green tea and vitamin E enhance exercise-induced benefits in body composition, glucose homeostasis, and antioxidant status in elderly men and women.

OBJECTIVE: To investigate the effects of green tea plus vitamin E in addition to exercise on body composition and metabolic and antioxidant parameters in healthy elderly individuals. DESIGN: Interventional randomized controlled prospective trial. METHODS: For 12 weeks, 22 elderly men and women (age: 71.1 ± 1.2 years; body mass index: 28.3 ± 0.5 kg/m(2) [mean ± SE]) undertook 30 minutes of moderately intense walking 6 d/wk. They were randomly assigned to ingest either green tea plus vitamin E (GTVE; 3 cups and 400 IU, respectively; n = 11) or placebo (n = 11). Data on anthropometrics, fasting insulin and glucose levels, physical fitness, dietary intake, safety parameters, and biomarkers of oxidation status were recorded and analyzed at the start and end of the study. RESULTS: Though dietary intake was unchanged, improved exercise capacity was followed by a significant reduction in body weight and fasting insulin levels in all participants. Additional consumption of GTVE resulted in a twofold increase in serum vitamin E (from 20.4 to 40.6 µmol/L, p < 0.001) and a decrease of men's and women's waist circumferences (from 100.8 and 95.7 to 96.9 and 85.0 cm, p < 0.05 and p < 0.01, respectively) and fasting glucose levels (from 5.30 to 4.98 mmol/L, p < 0.01). Plasma protein carbonyls dropped (from 0.93 to 0.77 nmol/mg protein, p < 0.05), whereas erythrocyte catalase activities increased (from 26.7 to 29.7 U/g hemoglobin, p < 0.05) in the GTVE group only. Oral peroxidase activities were increased in both groups. CONCLUSIONS: A daily dose of GTVE in healthy elderly men and women may improve exercise-induced benefits in body composition and glucose tolerance and may also lower oxidative burden.

Involvement of NF-κB and muscle specific E3 ubiquitin ligase MuRF1 in cigarette smoke-induced catabolism in C2 myotubes.

Cigarette smoking has been identified as a risk factor for muscular damage and sarcopenia, the age-related loss of muscle mass and strength in old age. Cigarette smoke (CS)-induced oxidative stress and p38 MAPK activation have been shown to be the main cellular mechanisms leading to skeletal muscle catabolism. In order to investigate the involvement of NF-κB as another possible cellular mechanism by which CS promotes muscle catabolism, C2 myotubes, from an in vitro skeletal muscle cell line, were exposed to different time periods of whole vapor phase CS in the presence or absence of NF-κB inhibitor, IMD-0354. The CS-induced reduction in diameter of myotubes and time-dependent degradation of the main contractile protein myosin heavy chain were abolished by NF-κB inhibition. Also, C2 exposure to CS resulted in IκB-α degradation and NF-κB activation, which led to upregulation of the muscle specific E3 ubiquitin ligase MuRF1, but not MAFbx/atrogin-1. In conclusion, our results demonstrate that vapor phase CS exposure to skeletal myotubes triggers NF-κB activation leading to skeletal muscle cell damage and breakdown of muscle proteins mediated by muscle specific E3 ubiquitin ligase MuRF1. Our findings provide another possible molecular mechanism for the catabolic effects of CS in skeletal muscle.

The effects of acetaldehyde and acrolein on muscle catabolism in C2 myotubes.

The toxic aldehydes acetaldehyde and acrolein were previously suggested to damage skeletal muscle. Several conditions in which exposure to acetaldehyde and acrolein is increased were associated with muscle wasting and dysfunction. These include alcoholic myopathy, renal failure, oxidative stress, and inflammation. A main exogenous source of both acetaldehyde and acrolein is cigarette smoking, which was previously associated with increased muscle catabolism. Recently, we have shown that exposure of skeletal myotubes to cigarette smoke stimulated muscle catabolism via increased oxidative stress, activation of p38 MAPK, and upregulation of muscle-specific E3 ubiquitin ligases. In this study, we aimed to investigate the effects of acetaldehyde and acrolein on catabolism of skeletal muscle. Skeletal myotubes differentiated from the C2 myoblast cell line were exposed to acetaldehyde or acrolein and their effects on signaling pathways related to muscle catabolism were studied. Exposure of myotubes to acetaldehyde did not promote muscle catabolism. However, exposure to acrolein caused increased generation of free radicals, activation of p38 MAPK, upregulation of the muscle-specific E3 ligases atrogin-1 and MuRF1, degradation of myosin heavy chain, and atrophy of myotubes. Inhibition of p38 MAPK by SB203580 abolished acrolein-induced muscle catabolism. Our findings demonstrate that acrolein but not acetaldehyde activates a signaling cascade resulting in muscle catabolism in skeletal myotubes. Although within the limitations of an in vitro study, these findings indicate that acrolein may promote muscle wasting in conditions of increased exposure to this aldehyde.

Cigarette smoking and inflammation revisited.

Despite the significant health risks resulting from tobacco use, the prevalence of smokers worldwide remains high. Cigarette smoking is one of the major sources of toxic chemical exposure to humans and is the greatest cause of preventable illnesses and premature death. The adverse consequences of smoking in various pathologies are mediated by its effects on the immune-inflammatory system. In this review, we aim to explore the effects of cigarette smoking on the inflammatory response and molecular mechanisms with emphasis on the nuclear factor kappa B (NF-kB) pathway. The effects of smoking on various inflammatory pathologies will be discussed, focusing on oral diseases, airway inflammation, chronic obstructive pulmonary disease (COPD) and inflammatory bowel diseases (IBD).

Assessment of IL-1ß and VEGF concentration in a rat model during orthodontic tooth movement and extracorporeal shock wave therapy.

OBJECTIVE: This study aimed to investigate PDL's cytokine concentration fluctuations after induction of orthodontic force with and without extracorporeal shock wave therapy in a rat model. MATERIALS AND METHODS: An orthodontic appliance was fabricated and applied between the molars and the incisors of rats. The rats were treated by a single episode of 1000 shock waves and gingival crevicular fluid was collected for 3 days. The expression and concentration of IL-1ß and VEGF were evaluated by ELISA assay. On day 3 all rats were sacrificed and histologic and immunohistochemical assays were applied. RESULTS: IL-1ß concentration rose in both the treated and non treated shockwave groups on the first day, however it was statistically significantly higher in the treated group on day 2. No statistically significant difference was detected between the groups on day 3. The number/area of TRAP positive cells was higher in the non shockwave group than in the treated group. The percentage of cells expressing VEGF displayed the opposite trend. The findings regarding the immunohistochemical assay for IL-1ß corresponded with those of the ELISA assay on day 3. CONCLUSION: The application of shockwaves during orthodontic tooth movement influences the expression of IL-1ß and VEGF and may alternate the periodontal remodelling expected rate.

Green tea and its major polyphenol EGCG increase the activity of oral peroxidases.

Oral peroxidases (OPO) consist mainly of salivary peroxidase and myeloperoxidase and are involved in oral defense mechanisms. Salivary peroxidase is synthesized and secreted by salivary glands, whereas myeloperoxidase is found in polymorphonuclear leukocytes, which migrate into the oral cavity at gingival crevices. Green tea is the world's second most popular drink after water. Polyphenols are the most biologically active group of tea components. The purpose of our study was to elucidate the interaction between green tea & EGCG (Epigallocatechin 3-gallate), its main polyphenol and OPO. In previous studies we have shown that elderly trained people who drink green tea for 3 months, have a higher level of OPO activity compared to non-drinkers. Thus, we decided to extend our project in order to understand the above observations by studying the interaction of green tea and OPO both in vitro and in vivo. Addition of green tea and black tea infusions (50 µl/ml) and EGCG (50 µM) to saliva, resulted in a sharp rise of OPO activity +280% (p = 0.009), 54% (p = 0.04) and 42% (p = 0.009), respectively. The elevation of OPO activity due to addition of green tea and EGCG was in a dose dependent manner: r = 0.91 (p = 0.001) and r = 0.637 (p = 0.019), respectively. Also, following green tea infusion mouth rinsing, a rise of OPO activity was observed: +268% (p = 0.159). These results may be of great clinical importance, as tea consumer's oral epithelium may have better protection against the deleterious effects of hydroxyl radicals, produced by not removed hydrogen peroxides in the presence of metal ions. Higher OPO activity upon green tea drinking may provide an extra protection against oxidative stress in the oral cavity.

Cigarette smoke and muscle catabolism in C2 myotubes.

Previous studies have revealed evidence of muscular damage and up-regulation of genes associated with impaired muscle maintenance in smokers. Cigarette smoking has also been associated with sarcopenia, the age-related loss of muscle mass and strength. In order to investigate the cellular mechanisms by which cigarette smoke (CS) promotes muscle catabolism, C2 myotubes from an in vitro skeletal muscle cell line, were exposed to different levels of whole vapor phase CS using a controlled CS exposure apparatus. Exposure of C2 myotubes to CS caused a reduction in diameter of myotubes and a time- and dose-dependent degradation of myosin heavy chain. Also, CS exposure resulted in increased intracellular oxidative stress and p38 MAPK phosphorylation, which led to up-regulation of the muscle specific E3 ubiquitin ligases: MAFbx/atrogin-1 and MuRF1. Pretreatment with the antioxidant N-acetylcysteine and inhibition of p38 MAPK by SB203580 prevented CS induced catabolism. In conclusion, our results demonstrate that exposure of skeletal myotubes to CS leads to increased oxidative stress and activation of the p38 MAPK pathway resulting in muscle cell atrophy and breakdown of muscle protein mediated by muscle specific E3 ubiquitin ligases. Our findings provide a possible molecular mechanism for the catabolic effects of CS in skeletal muscle.

Sarcopenia and smoking: a possible cellular model of cigarette smoke effects on muscle protein breakdown.

Sarcopenia, the age-related loss of muscle mass and strength, is a multifactorial impaired state of health. Lifestyle habits such as physical activity and nutrition have a major impact on sarcopenia progression. Several epidemiological studies have also shown an association between cigarette smoking and increased levels of sarcopenia in elderly long-time smokers. Clinical, in vivo, and in vitro studies have tried to investigate the mechanism behind exposure to cigarette smoke (CS) and the subsequent effects on skeletal muscles. The aim of this review is to present a cellular model of CS-induced skeletal muscle protein breakdown based on recent studies dealing with this issue and to propose new potential research directions that may explain the effects of exposure to CS on skeletal muscle integrity.

Identification of possible cigarette smoke constituents responsible for muscle catabolism.

The age-related loss of muscle mass and strength also known as sarcopenia is significantly influenced by life style factors such as physical inactivity and impaired nutrition. Cigarette smoking is another life style habit that has been shown to be associated with sarcopenia and to affect skeletal muscle. Even today, smoking is still prevalent worldwide and is probably the most significant source of toxic chemicals exposure to humans. Cigarette smoke (CS) is a complex aerosol consisting of thousands of various constituents including reactive oxygen and nitrogen free radicals, toxic aldehydes and more. Previous epidemiological studies have identified tobacco smoking as a risk factor for sarcopenia. Clinical, in vivo and in vitro studies have revealed CS-induced skeletal muscle damage due to impaired muscle metabolism, increased inflammation and oxidative stress, over-expression of atrophy related genes and activation of various intracellular signaling pathways. This review aims to discuss and identify the components of CS that may promote catabolism of skeletal muscle.