Mechanisms underlying the cardioprotective effect of l-cysteine

Removal of hazardous ions from aqueous solutions: Current methods, with a focus on green ion flotation

Hazardous ions, like those of heavy metals, cause significant health and environmental problems when they are discharged into water resources naturally or through various industrial processes. Removing these ions from water is of significant importance in the provision of high-quality water for drinking and agricultural usage. This work discusses current techniques that are frequently used for the removal of heavy-metal ions from aqueous solutions by absorption, particularly the use of biodegradable surfactants in ion flotation. Certain new surfactants promise high efficiency in their use in the ion-flotation process and in their application in industrial-water treatment to remove heavy metals. As an example, this work demonstrates the high efficiency of surfactants based on an amino-acid (L-cysteine) in removing a range of heavy-metal ions in a simple, single-stage ion-flotation process. High foaming ability, the ability to operate in various temperatures and pHs, decomposing into natural products and high binding affinity for heavy-metal ions make the cysteine-based surfactants a highly suitable compound to replace current commercial surfactants in ion- and froth-flotation processes. Removal of particular ions can also be achieved in ion flotation; a suitable choice of parameters, such as pH and surfactant concentration, favours the surfactant binding to those ions. Further intensive work is required to develop an optimal process to recover valuable elements from waste solutions.

Thermal Stability and Degradation Kinetics of Patulin in Highly Acidic Conditions: Impact of Cysteine

The thermal stability and degradation kinetics of patulin (PAT, 10 μmol/L) in pH 3.5 of phosphoric-citric acid buffer solutions in the absence and presence of cysteine (CYS, 30 μmol/L) were investigated at temperatures ranging from 90 to 150 °C. The zero-, first-, and second-order models and the Weibull model were used to fit the degradation process of patulin. Both the first-order kinetic model and Weibull model better described the degradation of patulin in the presence of cysteine while it was complexed to simulate them in the absence of cysteine with various models at different temperatures based on the correlation coefficients (R² > 0.90). At the same reaction time, cysteine and temperature significantly affected the degradation efficiency of patulin in highly acidic conditions (p < 0.01). The rate constants (k_T) for patulin degradation with cysteine (0.0036-0.3200 μg/L·min) were far more than those of treatments without cysteine (0.0012-0.1614 μg/L·min), and the activation energy (E_a = 43.89 kJ/mol) was far less than that of treatment without cysteine (61.74 kJ/mol). Increasing temperature could obviously improve the degradation efficiency of patulin, regardless of the presence of cysteine. Thus, both cysteine and high temperature decreased the stability of patulin in highly acidic conditions and improved its degradation efficiency, which could be applied to guide the detoxification of patulin by cysteine in the juice processing industry.

Antioxidant effects of N-acetylcysteine on the male reproductive system: A systematic review

This study aimed to evaluate the effect of N-acetyl cysteine on the male reproductive system and consensus and classification of data found from previous studies. It is undeniable that N-acetyl cysteine as a powerful antioxidant compound can medicate many diseases such as cardiovascular, kidney, liver and reproductive system disorders. With the increasing environmental pollution that has a direct adverse effect on male fertility, the use of this compound is able to positively function on human fertility health. In this study, we have been collected the main data of scientific articles (1994-2020) about N-acetyl cysteine effects. By searching in the scientific databases of PubMed, Google Scholar, Science Direct, Wiley and Web of Science, related articles were extracted. As a result, all observations have confirmed that N-acetyl cysteine can improve and normalise the spermatogenesis in the male reproduction system.

Comparison of the Plasma Metabolome Profiles Between the Internal Thoracic Artery and Ascending Aorta in Patients Undergoing Coronary Artery Bypass Graft Surgery Using Gas Chromatography Time-of-Flight Mass Spectrometry

BACKGROUND

The left internal thoracic artery (LITA) has been used as the first conduit of choice in coronary artery bypass grafting (CABG) because of excellent long-term patency and outcomes. However, no studies have examined substances other than nitric oxide that could be beneficial for the bypass conduit, native coronary artery or ischemic myocardium. This study was conducted to evaluate differences in metabolic profiles between the LITA and ascending aorta using gas chromatography-time of flight-mass spectrometry (GC-TOF-MS).

METHODS

Twenty patients who underwent CABG using the LITA were prospectively enrolled. Plasma samples were collected simultaneously from the LITA and ascending aorta. GC-TOF-MS based untargeted metabolomic analyses were performed and a 2-step volcano plot analysis was used to identify distinguishable markers from two plasma metabolome profiles. Semi-quantitative and quantitative analyses were performed using GC-TOF-MS and enzyme-linked immunosorbent assay, respectively, after selecting target metabolites based on the metabolite set enrichment analysis.

RESULTS

Initial volcano plot analysis demonstrated 5 possible markers among 851 peaks detected. The final analysis demonstrated that the L-cysteine peak was significantly higher in the LITA than in the ascending aorta (fold change = 1.86). The concentrations of intermediate metabolites such as L-cysteine, L-methionine and L-cystine in the 'cysteine and methionine metabolism pathway' were significantly higher in the LITA than in the ascending aorta (2.0-, 1.4- and 1.2-fold, respectively). Quantitative analysis showed that the concentration of hydrogen sulfide (H₂S) was significantly higher in the LITA.

CONCLUSION

The plasma metabolome profiles of the LITA and ascending aorta were different, particularly higher plasma concentrations of L-cysteine and H₂S in the LITA.

Inflammation, oxidative stress and postoperative atrial fibrillation in cardiac surgery

Postoperative atrial fibrillation (POAF) is a common complication of cardiac surgery that occurs in up to 60% of patients. POAF is associated with increased risk of cardiovascular mortality, stroke and other arrhythmias that can impact on early and long term clinical outcomes and health economics. Many factors such as disease-induced cardiac remodelling, operative trauma, changes in atrial pressure and chemical stimulation and reflex sympathetic/parasympathetic activation have been implicated in the development of POAF. There is mounting evidence to support a major role for inflammation and oxidative stress in the pathogenesis of POAF. Both are consequences of using cardiopulmonary bypass and reperfusion following ischaemic cardioplegic arrest. Subsequently, several anti-inflammatory and antioxidant drugs have been tested in an attempt to reduce the incidence of POAF. However, prevention remains suboptimal and thus far none of the tested drugs has provided sufficient efficacy to be widely introduced in clinical practice. A better understanding of the cellular and molecular mechanisms responsible for the onset and persistence of POAF is needed to develop more effective prediction and interventions.

Cardioprotective Effects of Cysteine Alone or in Combination With Taurine in Diabetes

This study was undertaken to examine the effects of dietary supplementation of cysteine and taurine in rats with diabetes induced with streptozotocin (STZ, 65 mg/kg body weight). Experimental animals were treated orally (by gavage) with cysteine (200 mg/kg) and taurine (400 mg/kg), alone or in combination, daily for 8 weeks. In one group, rats were also pretreated 3 weeks before the induction of diabetes (prevention arm) whereas in the other, the treatment was started 3 days after the induction of diabetes (reversal arm). Diabetes increased heart weight/body weight (HW/BW) ratio, plasma glucose, triglyceride and cholesterol levels as well as depressed heart rate (HR), blood pressure, left ventricular systolic pressure (LVSP), rate of contraction (+dP/dt), rate of relaxation (-dP/dt), fractional shortening (FS) and cardiac output (CO). The left ventricular internal diameter in systole (LViDs) was increased whereas that in diastole (LViDd) was decreased. In the prevention arm, treatment of the diabetic animals with cysteine or taurine decreased HW/BW ratio and improved HR, FS, +dP/dt and -dP/dt, as well as normalized LViDs, without altering the increase in glucose level. Cysteine decreased plasma triglyceride and cholesterol levels and improved LVSP whereas CO was improved by taurine. In the reversal arm, cysteine alone or with taurine did not correct the changes in hemodynamic parameters, FS and plasma triglycerides. Diabetes-induced cardiac dysfunction and increases in plasma triglycerides can be prevented, but not reversed, by dietary cysteine alone or in combination with taurine.

Effect of (L)-cysteine on acetaldehyde self-administration

Acetaldehyde (ACD), the first metabolite of ethanol, has been implicated in several behavioural actions of alcohol, including its reinforcing effects. Recently, we reported that l-cysteine, a sequestrating agent of ACD, reduced oral ethanol self-administration and that ACD was orally self-administered. This study examined the effects of l-cysteine pre-treatment during the acquisition and maintenance phases of ACD (0.2%) self-administration as well as on the deprivation effect after ACD extinction and on a progressive ratio (PR) schedule of reinforcement. In a separate PR schedule of reinforcement, the effect of l-cysteine was assessed on the break-point produced by ethanol (10%). Furthermore, we tested the effect of l-cysteine on saccharin (0.2%) reinforcement. Wistar rats were trained to self-administer ACD by nose poking on a fixed ratio (FR1) schedule in 30-min daily sessions. Responses on an active nose-poke caused delivery of ACD solution, whereas responses on an inactive nose-poke had no consequences. l-cysteine reduced the acquisition (40 mg/kg), the maintenance and the deprivation effect (100 mg/kg) of ACD self-administration. Furthermore, at the same dose, l-cysteine (120 mg/kg) decreased both ACD and ethanol break point. In addition, l-cysteine was unable to suppress the different responses for saccharin, suggesting that its effect did not relate to an unspecific decrease in a general motivational state. Compared to saline, l-cysteine did not modify responses on inactive nose-pokes, suggesting an absence of a non-specific behavioural activation. Taken together, these results could support the hypotheses that ACD possesses reinforcing properties and l-cysteine reduces motivation to self-administer ACD.

Oxidative stress increases SNAT1 expression and stimulates cysteine uptake in freshly isolated rat cardiomyocytes

Intracellular cysteine availability is an important rate-limiting factor governing glutathione synthesis in the heart. This is also dependent on the magnitude and rate of cysteine uptake into cardiomyocytes, which has been little studied. This study investigated the hypothesis that changes to cysteine transporter expression and activity during oxidative stress influence cardiomyocyte glutathione levels. The uptake of 0-3 mM L-[(35)S]cysteine into ventricular cardiomyocytes isolated from adult male Wistar rats was measured using oil filtration. Cysteine transporter expression was investigated by conventional and real-time quantitative reverse-transcription polymerase chain reaction and Western blotting. Glutathione levels were measured enzymatically. Oxidative stress was induced via 0-6 h incubation with 0.05 mM H(2)O(2). Cysteine uptake was greatest in sodium-containing media and was inhibited by glutamine, 2-(methylamino)-isobutyric acid (αMeAIB), serine or alanine. The K(m) and V(max) of the αMeAIB insensitive and sensitive portions were 0.133 ± 0.01 mM and 468.11 ± 9.04 pmol/μl cell vol/min, and 0.557 ± 0.096 mM and 279.87 ± 16.06 pmol/μl cell vol/min, respectively. Cardiomyocytes expressed ASCT2, SNAT1 and SNAT2 but not ASCT1. Oxidative stress significantly enhanced cysteine uptake, which was attenuated by αMeAIB. This was accompanied by significantly enhanced SNAT1 expression, whilst SNAT2 and ASCT2 were unaffected. Incubation with cysteine significantly reduced the oxidative-stress-induced decline in cardiomyocyte glutathione as compared to cells incubated without cysteine or cells incubated with cysteine and αMeAIB. In conclusion, under control conditions SNAT transporters aid in the delivery of cysteine for cardiomyocyte GSH synthesis, whilst oxidative stress increases cardiomyocyte cysteine uptake and stimulates cardiomyocyte SNAT1 expression.

Cysteine protects freshly isolated cardiomyocytes against oxidative stress by stimulating glutathione peroxidase

Cysteine has been implicated in myocardial protection, although this is controversial and constrained by limited knowledge about the effects of cysteine at the cellular level. This study tested the hypothesis that a physiologically relevant dose of L: -cysteine could be safely loaded into isolated cardiomyocytes leading to improved protection against oxidative stress. Freshly isolated adult rat ventricular cardiomyocytes were incubated for 2 h at 37°C with (cysteine incubated) or without (control) 0.5 mM cysteine prior to washing and suspension in fresh cysteine-free media. Cysteine incubated cells had higher intracellular cysteine levels compared to controls (9.6 ± 0.78 vs. 6.5 ± 0.65 nmol/mg protein, P < 0.02, n = 6 ± SE). Cell homeostasis indicators were similar in the two groups. Cysteine incubated cells had significantly higher glutathione peroxidase (GPx) activity (1.11 ± 0.23 vs. 0.54 ± 0.1 U/mg protein, P < 0.05, n = 5 ± SE) and significantly greater expression of GPx-1 (5.01 ± 0.48 vs. 3.01 ± 0.25 OD units/mm(2), P < 0.05, n = 4 ± SE) compared to controls. Upon exposure to H(2)O(2), cysteine incubated cells generated fewer reactive oxygen species and took longer to show contractile changes and undergo hypercontracture. However, when cells were exposed to H(2)O(2) in the presence of 0.05 mM of the GPx inhibitor mercaptosuccinic acid, this increased the control cells' susceptibility to H(2)O(2) and completely abolished the cysteine mediated protection. These results suggest a new role for cysteine in myocardial protection involving stimulation of glutathione peroxidase.

L-cysteine stimulates hydrogen sulfide synthesis in myocardium associated with attenuation of ischemia-reperfusion injury

Hydrogen sulfide (H( 2)S) is a biological mediator produced by enzyme-regulated pathways from L-cysteine, which is a substrate for cystathionine-gamma-lyase (CSE). In myocardium, endogenously and exogenously administered H(2)S has been shown to protect against ischemia-reperfusion injury. We hypothesized that L-cysteine exerts its protective action through stimulation of H(2)S production. Rat isolated hearts were Langendorff-perfused and underwent 35-minute regional ischemia and 120-minute reperfusion. L-cysteine perfusion from 10 minutes before ischemia until 10 minutes after reperfusion limited infarct size in a concentration-dependent manner, maximal at 1 mmol/L (control 36.4% +/- 2.4% vs L-cysteine 24.3% +/- 3.4%, P < .05). This protective action was attenuated by the CSE inhibitor, DL-propargylglycine (PAG) 1 mmol/L (31.4 +/- 5.9%, not significant vs control) but administration of the CSE cofactor pyridoxal-5'-phosphate (PLP) 50 mumol/L did not enhance the effect of L-cysteine. Ten minutes normoxic perfusion with L-cysteine 1 mmol/L caused a 3-fold increase in myocardial H(2)S concentration (0.64 +/- 0.16 vs 2.01 +/- 0.07 mumol/g protein, P < .01), an effect that was significantly attenuated by PAG (1.17 +/- 0.15 mumol/g protein). These data provide evidence that exogenous L-cysteine administration limits ischemia-reperfusion injury through a mechanism that appears to be at least partially dependent on H(2)S synthesis.

The use of comparative quantitative RT-PCR to investigate the effect of cysteine incubation on GPx1 expression in freshly isolated cardiomyocytes

Intracellular cysteine availability is one of the major rate limiting factors that regulate the synthesis of the major antioxidant, glutathione. Little is known, however, about the effect of cysteine upon glutathione-associated enzymes in isolated heart cells. Such knowledge is important if a full understanding and exploitation of cysteine's cardioprotective potential is to be achieved. Therefore, this study describes the use of a comparative quantitative reverse transcription polymerase chain reaction (RT-PCR) assay to investigate the effect of incubation of freshly isolated rat cardiomyocytes for 2 h at 37 degrees C with or without 0.5 mM cysteine on the expression of cellular glutathione peroxidase (GPx1). The main analytical method is the conventional RT-PCR in a standard thermal cycler followed by electrophoresis and scanning densitometry using the expression of the housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), for normalising purposes. Each step of this straight-forward and relatively inexpensive method is explained in detail to facilitate its adoption by the reader for experiments investigating the effects of any compound on any gene in any cell population. The results of the current investigation show that cysteine incubation significantly increases the expression of GPx1 in freshly isolated cardiomyocytes compared to control, suggesting the possibility of a new beneficial role for cysteine in myocardial protection.

l-Cysteine reduces oral ethanol self-administration and reinstatement of ethanol-drinking behavior in rats

Our previous findings have shown that l-cysteine, a non essential amino acid, prevented ethanol (EtOH) induced conditioned place preference. The aim of the present study was to examine the effect of l-cysteine on the acquisition and maintenance of oral EtOH self-administration and on the reinstatement of EtOH-drinking behavior in Wistar rats. Rats were pretreated intraperitoneally with saline or l-cysteine (20 and 40 mg/kg) 30 min before each acquisition trial, in an operant nose-poking paradigm where they were given the opportunity to orally self-administer tap water or EtOH (5-10% v/v). Further, to evaluate if l-cysteine reduces the acquired oral EtOH self-administration, we carried out an independent experiment in which rats were trained to self-administer EtOH (10%); after all groups of rats developed similarly stable oral EtOH self-administration, the effect of l-cysteine (0, 40, 60, 80 and 100mg/kg) was tested. An additional group of rats was pretreated with saline or l-cysteine (80 mg/kg) and tested on reinstatement after EtOH extinction and, at the end of last reinstatement session, were utilized to measure blood and brain EtOH levels. The animals that had access to EtOH solution discriminated between the active and inactive nose-pokes and showed rates of active nose-pokes significantly higher than the tap water group. Furthermore, rats self-administering EtOH (10%) also demonstrated extinction behavior and gradually reinstated active nose-poke responding when EtOH was reintroduced. l-cysteine reduced both the acquisition and maintenance of oral EtOH self-administration. The reduced reinstatement of EtOH-drinking behavior was paralleled by a significant reduction of EtOH intake and correlated with blood and brain EtOH levels. The efficacy of l-cysteine on the various phases of alcohol drinking in rats, could represent an interesting pharmacological approach and could open a new line of research for the development of therapies to reduce EtOH intake in alcoholic patients.

Reduction of ethanol-derived acetaldehyde induced motivational properties by L-cysteine

BACKGROUND

Experimental evidences suggest that acetaldehyde (ACD) contributes to the positive motivational properties of ethanol (EtOH) as assessed by the place conditioning paradigm; indeed, we found that by reducing ACD production and/or by using ACD-sequestrating agents, EtOH is deprived from its motivational properties. Thiol products, such as the amino acid cysteine, are known to be effective ACD-sequestering agents. Cysteine is able to covalently bind ACD thereby forming a stable, nontoxic 2-methyl-thiazolidine-4-carboxylic acid compound. Thus, we treated rats with l-cysteine before intragastric administration of EtOH or ACD.

METHODS

Male Wistar rats were pretreated intraperitoneally with saline or l-cysteine (10, 20, or 30 mg/kg), before intragastric administration of saline, EtOH (1 g/kg), or ACD (20 mg/kg). The specificity of l-cysteine effect was addressed using morphine-induced conditioned place preference (cpp) (2.5 mg/kg, i.p.).

RESULTS

l-cysteine dose-dependently prevented both EtOH and ACD-induced cpp but did not interfere with morphine-induced cpp, suggesting that l-cysteine specifically modulates the motivational properties of EtOH.

CONCLUSION

The present results further underscore the role of EtOH-derived ACD in EtOH-induced motivational properties. l-cysteine, by binding EtOH-derived ACD, would deprive it of its rewarding properties and reduce its abuse liability.

Role of oxidative stress in PKC-δ upregulation and cardioprotection induced by chronic intermittent hypoxia

The aim was to determine whether increased oxidative stress during the adaptation to chronic intermittent hypoxia (CIH) plays a role in the induction of improved cardiac ischemic tolerance. Adult male Wistar rats were exposed to CIH in a hypobaric chamber (7,000 m, 8 h/day, 5 days/wk, 24–30 exposures). Half of the animals received antioxidant N-acetylcysteine (NAC; 100 mg/kg) daily before the exposure; the remaining rats received saline. Control rats were kept under normoxia and treated in a corresponding manner. One day after the last exposure (and/or NAC injection), anesthetized animals were subject to 20 min of coronary artery occlusion and 3 h of reperfusion for determination of infarct size. In parallel subgroups, biochemical analyses of the left ventricular myocardium were performed. Adaptation to CIH reduced infarct size from 56.7 ± 4.5% of the area at risk in the normoxic controls to 27.7 ± 4.9%. NAC treatment decreased the infarct size in the controls to 42.0 ± 3.4%, but it abolished the protection provided by CIH (to 41.1 ± 4.9%). CIH decreased the reduced-to-oxidized glutathione ratio and increased the relative amount of PKC isoform-δ in the particulate fraction; NAC prevented these effects. The expression of PKC-ε was decreased by CIH and not affected by NAC. Activities of superoxide dismutase, catalase, and glutathione peroxidase were affected by neither CIH nor NAC treatment. It is concluded that oxidative stress associated with CIH plays a role in the development of increased cardiac ischemic tolerance. The infarct size-limiting mechanism of CIH seems to involve the PKC-δ-dependent pathway but apparently not the increased capacity of major antioxidant enzymes.