Cannabidiol protects C2C12 myotubes against cisplatin-induced atrophy by regulating oxidative stress

Cancer and chemotherapy induce a severe loss of muscle mass (known as cachexia), which negatively impact cancer treatment and patient survival. The aim of the present study was to investigate whether cannabidiol (CBD) administration may potentially antagonize the effects of cisplatin in inducing muscle atrophy, using a model of myotubes in culture. Cisplatin treatment resulted in a reduction of myotube diameter (15.7 ± 0.3 vs. 22.2 ± 0.5 µm, P < 0.01) that was restored to control level with 5 µM CBD (20.1 ± 0.4 µM, P < 0.01). Protein homeostasis was severely altered with a ≈70% reduction in protein synthesis (P < 0.01) and a twofold increase in proteolysis (P < 0.05) in response to cisplatin. Both parameters were dose dependently restored by CBD cotreatment. Cisplatin treatment was associated with increased thiobarbituric acid reactive substances (TBARS) content (0.21 ± 0.03 to 0.48 ± 0.03 nmol/mg prot, P < 0.05), catalase activity (0.24 ± 0.01 vs. 0.13 ± 0.02 nmol/min/µg prot, P < 0.01), whereas CBD cotreatment normalized TBARS content to control values (0.22 ± 0.01 nmol/mg prot, P < 0.01) and reduced catalase activity (0.17 ± 0.01 nmol/min/µg prot, P < 0.05). These changes were associated with increased mRNA expression of GPX1, SOD1, SOD2, and CAT mRNA expression in response to cisplatin (P < 0.01), which was corrected by CBD cotreatment (P < 0.05). Finally, cisplatin treatment increased the mitochondrial protein content of NDUFB8, UQCRC2, COX4, and VDAC1 (involved in mitochondrial respiration and apoptosis), and CBD cotreatment restored their expression to control values. Altogether, our results demonstrated that CBD antagonize the cisplatin-induced C2C12 myotube atrophy and could be used as an adjuvant in the treatment of cancer cachexia to help maintain muscle mass and improve patient quality of life.NEW & NOTEWORTHY In an in vitro model, cisplatin treatment led to myotube atrophy associated with dysregulation of protein homeostasis and increased oxidative stress, resulting in increased apoptosis. Cotreatment with cannabidiol was able to prevent this phenotype by promoting protein homeostasis and reducing oxidative stress.

Effects of fullerene C60 on liver tissue in liver ischemia reperfusion injury in rats undergoing sevoflurane anesthesia

This study aimed to investigate the effects of fullerene C60 on rat liver tissue in a liver ischemia reperfusion injury (IRI) model under sevoflurane anesthesia to evaluate the ability of nanoparticles to prevent hepatic complications. A total of 36 adult female Wistar Albino rats were divided into six groups, each containing six groups as follows: sham group (Group S), fullerene C60 group (Group FC60), ischemia-reperfusion group (Group IR), ischemia-reperfusion-sevoflurane group (Group IR-Sevo), ischemia-reperfusion-fullerene C60 group (Group IR-FC60), and ischemia-reperfusion-fullerene C60-sevoflurane group (Group IR-FC60-Sevo). Fullerene C60 100 mg/kg was administered to IR-FC60 and IR-FC60-Sevo groups. In the IR group, 2 h of ischemia and 2 h of reperfusion were performed. At the end of reperfusion, liver tissues were removed for biochemical assays and histopathological examinations. Hepatocyte degeneration, sinusoidal dilatation, prenecrotic cells, and mononuclear cell infiltration in the parenchyma were significantly higher in Group IR than in all other groups. Thiobarbituric acid reactive substances levels were significantly higher in Group IR than in the other groups, and the lowest thiobarbituric acid reactive substances level was in Group IR-FC60 than in the other groups, except for Groups S and FC60. Catalase and Glutathione-S-transferase activities were reduced in the IR group compared to all other groups. Fullerene C60 had protective effects against liver IR injury in rats under sevoflurane anesthesia. The use of fullerene C60 could reduce the adverse effects of IRI and the associated costs of liver transplantation surgery.

Oxidation of biological molecules with age and induced oxidative stress in different growth phases of Saccharomyces cerevisiae

One of the mechanistic approaches for explaining ageing is the oxidative stress theory of ageing. Saccharomyces cerevisiae has been used as a model to study ageing due to many factors. We have attempted to investigate if the differential ability to withstand oxidative stress can be correlated with their lifespans. In all the four strains studied (AP22, 699, 8C, and SP4), there was no age-associated increases in lipid peroxidation levels measured as thiobarbituric acid reactive substances (TBARS). Under induced oxidative stress conditions, there was an increased TBARS level in both the ages assessed with a quantum-fold increase in the stationary phase cells of AP22. In contrast, the late stationary phase cells of 8C exhibited the least susceptibility to induced oxidative stress. The level of TBARS in both exponential and late stationary phase cells of 699 was overall more than that in the other three strains. Protein carbonylation increased with age in 8C and 699. Induced stress increased carbonylation in the exponential cells of SP4 and 699 and the stationary phase cells of all four strains. Protein carbonylation data indicate that the AP22 cells exhibit decreased protein carbonylation vis-à-vis the other strains. Induced stress data showed that while the exponential cells of 699 are susceptible, the late stationary phase cells of 699 are most resistant. Western blotting analysis using anti-HNE antibodies showed two proteins of molecular mass ~ 56 and ~ 84 kDa that were selectively modified with age in all the strains. Under induced stress conditions, an additional protein of ~ 69 kDa was oxidized. Our investigation shows that the difference in lifespan between the four strains of S. cerevisiae may be regulated by oxidative stress. Knowledge of the identity of the oxidized proteins will significantly facilitate a better understanding of the effect of oxidative stress conditions on the cells of S. cerevisiae.

Protective Effects of Kefir Against Unpredictable Chronic Stress Alterations in Mice Central Nervous System, Heart, and Kidney

Kefir is a probiotic mixture with anxiolytic and antioxidant properties. Chronic stress can lead to anxiety disorders and increase oxidative damage in organs such as the heart and kidney. In this study, we examined whether kefir ameliorates the anxiety-like behavior of mice submitted to chronic unpredictable stress (CUS) by modulating brain-derived neurotrophic factor (BDNF) and corticosterone levels and whether kefir modifies the oxidative parameters in the heart and kidney of mice. Male Swiss mice received kefir (0.3 mL/100 g/day) or milk for 30 days (gavage). On the 10th day, the mice were submitted to CUS. Behavioral analysis was performed using the elevated plus maze and forced swimming tests. BDNF levels were analyzed in brain tissues. Heart and kidney superoxide dismutase (SOD), catalase, glutathione (GSH), thiobarbituric acid reactive substances (TBARS), 3-nitrotyrosine, metalloproteinase-2 (MMP-2), and plasma corticosterone were evaluated. Kefir reverted the CUS-induced decrease in the time spent in the open arms, the increase in grooming frequency, and decrease in the head dipping frequency, but not the reduced immobility time. CUS decreased the cerebellum BDNF levels and increased corticosterone levels, which were restored by Kefir. Neither catalase and SOD activities nor GSH, TBARS, 3-nitrotyrosine, and MMP-2 were modified by CUS in the heart. In the kidney, CUS increased 3-nitrotyrosine and MMP-2. Kefir increased the antioxidant defense in the heart and kidney of control and CUS mice. These results suggest that kefir ameliorated CUS-induced anxiety-like behavior by modulating brain BDNF and corticosterone levels. Kefir also increased the antioxidant defense of mice heart and kidney.

Evaluation of coronary function in female rats with severe type 1 diabetes: Effects of combined treatment with insulin and pyridoxamine

BACKGROUND

This study aimed to evaluate the coronary function, myocardium, and epicardial adipose tissue (EAT) in female rats with severe type 1 diabetes and the effects of combined treatment with insulin and pyridoxamine (AGEs inhibitor).

METHODS

Female Wistar rats were divided into groups: control (CTR, n = 13), type 1 diabetes (DM1, n = 12), type 1 diabetes treated with insulin (DM1 + INS, n = 11), and type 1 diabetes treated with insulin and pyridoxamine (DM1 + INS + PDX, n = 14). The vascular responsiveness was performed in the septal coronary artery and the protein expressions of AGE, RAGE, GPER, NF-kB was evaluated in the left ventricle (LV), as well as the reactive oxygen species (ROS) was measured in LV and in EAT. We analyzed plasma levels of glucose, estradiol, Nε-carboxymethylisine (CML), thiobarbituric acid reactive substances (TBARS), catalase (CAT), and superoxide dismutase (SOD).

RESULTS

The maximal responses to ACh were reduced in the DM1 compared with the CTR group, accompanied by an increase in circulating glucose, CML, and TBARS. Additionally, the expression of NF-kB in LV and generation of ROS in the presence of MnTMPyP (SOD mimetic) were increased in the DM1 group compared with CTR. Only the combined treatment was effective for fully re-establish ACh relaxation response, NF-kB protein expression, ROS generation, and increased SOD activity in the DM1 + INS + PDX group.

CONCLUSION

The reduction of the endothelium-dependent relaxation response in the septal coronary artery of female rats with severe type 1 diabetes was normalized with the combined treatment with insulin and pyridoxamine, associated with reduced inflammation and oxidative stress in the myocardium and increased circulating antioxidant activity.

Device-guided slow breathing alters postprandial oxidative stress in young adult males: A randomized sham-controlled crossover trial

BACKGROUND AND AIMS

Slow, deep breathing (SDB) lowers blood pressure (BP) though the underlying mechanisms are unknown. Redox improvements could facilitate hemodynamic adjustments with SDB though this has not been investigated. The purpose of this randomized, sham-controlled trial was to examine the acute effects of SDB on oxidative stress and endothelial function during a physiological perturbation (high-fat meal) known to induce oxidative stress.

METHODS AND RESULTS

Seventeen males (ages 18-35 years) were enrolled, and anthropometric measurements and 7-day physical activity monitoring were completed. Testing sessions consisted of 24-h diet recalls (ASA24), blood sample collection for superoxide dismutase (SOD) and thiobarbituric acid reactive substances (TBARS) analysis, and flow-mediated dilation (FMD). High-fat meals were ingested and 2-min breathing exercises (SDB or sham control breathing) were completed every 15 min during the 4-h postprandial phase. Blood sample collection and FMD were repeated 1-, 2-, and 4-h post meal consumption. Mean body mass index and step counts were 25.6 ± 4.3 kg/m2 and 8165 ± 4405 steps per day, respectively. Systolic and diastolic BP and nutrient intake 24 h prior were similar between conditions. No time or time by condition interaction effects were observed for FMD. The total area under the curve (AUC) for SOD was significantly lower during SDB compared to the sham breathing condition (p < 0.01). No differences were observed in TBARS AUC (p = 0.538).

CONCLUSIONS

Findings from the current investigation suggest that SDB alters postprandial redox in the absence of changes in endothelial function in young, healthy males.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04864184.

CLINICAL TRIALS IDENTIFIER

NCT04864184.

Diazinon toxicity in hepatic and spleen mononuclear cells is associated to early induction of oxidative stress

Diazinon is an organophosphorus pesticide, which may have potential toxic effects on the liver and immune system; however, the underlying mechanisms remain mostly unidentified. This work is aimed at evaluating the oxidative stress and cell cycle alterations elicited by low-dose diazinon in a rat liver cell line (BRL-3A) and spleen mononuclear cells (SMC) from Wistar rats. Diazinon (10-50 μM) caused early reactive oxygen species (ROS) generation (from 4 h) as well as increased O₂^•- level (from 0.5 h), which led to subsequent lipid peroxidation at 24 h, in BRL-3A cells. In SMC, diazinon (20 μM) produced similar increases in ROS levels, at 4 and 24 h, with the highest O₂^•- level being found at 4 h. Low-dose diazinon induced G1-phase arrest and cell death in hepatic cells and SMC. Therefore, diazinon could affect the liver and the immunological system through the premature oxidative stress induction.Abbreviations: O₂^•-: superoxide anion radical; ROS: reactive oxygen species; SMC: spleen mononuclear cells; TBARS: thiobarbituric acid reactive substances.

Investigation into the protective effects of Naringenin in phthalates-induced reproductive damage

OBJECTIVE

Di-n-butyl phthalate (DBP) is a ubiquitous environmental pollutant, extensively used as a plasticizer in many products, including plastics, cosmetics, and medical devices. Naringenin (NAR) is a flavonoid belonging to the flavanones subclass. It is widely distributed in several citrus fruits, bergamot, tomatoes, and other fruits. It is also found in its glycoside form (mainly naringin). Several biological activities have been ascribed to this phytochemical: antioxidant, antitumor, antiviral, antibacterial, anti-inflammatory, antiadipogenic, and cardioprotective effects. This study hypothesized that phthalates' possible reproductive damage mechanism is oxidative attack, and naringenin could have a protective effect against radical forms in the body through its antioxidant properties.

MATERIALS AND METHODS

Thirty-two male rats were used in our study (n=8 each). Rats were randomly divided into four groups: Control, DBP, DBP +NAR and NAR. Phthalate (DBP) and NAR were administered through gastric oral gavage (phthalate group 500 mg/kg/day DBP; NAR group 50 mg/kg/day NAR). At the end of four weeks, testis tissue samples were taken under anesthesia. Testis tissue and blood samples were collected from the four groups in this study. Histological, biochemical and spermatological analyses were conducted.

RESULTS

Tissue samples from the control and NAR groups showed normal histological appearance on light microscopy. The DBP group exhibited deterioration in seminiferous tubules, vascular congestion in capsule, vascular congestion between the seminiferous tubules, edema in the intestinal area and vacuolization, arrested spermatocytes in different stages of division; sloughing of cells into the seminiferous tubular lumen was observed. It was also observed that NAR treatment significantly inhibited and prevented the histopathological damage caused by DBP. Tissue TBARS, antioxidant parameters, sperm motility, sperm density and abnormal spermatozoon ratios were determined. As a result, it was shown that DBP caused oxidative damage by increasing TBARS levels and decreasing antioxidant parameters, increased abnormal sperm rate and decreased sperm motility, and concentration and histopathological damage, so the antioxidant activity of naringenin inhibited this damage.

CONCLUSIONS

DBP had toxic effects in rat testis tissue; NAR treatment ameliorated these effects. Further studies are warranted to confirm our findings.

Therapeutic effect of rocket seeds (Eruca sativa L.) against hydroxyapatite nanoparticles injection induced cardiac toxicity in rats

Hydroxyapatite is bio-ceramic materials with a calcium to phosphorus proportion like to that of normal bone and teeth. The current study meant to examine the cardiac toxicity by hydroxyapatite nanoparticles (HAP NPs) and the protective effect of the rocket seeds in treatments. An aggregate of 40 male Wistar rodents were partitioned into 4 equal groups [Gp1, control; Gp2, rocket seeds extract (RS); Gp3, HAP NPs; Gp4, HAP NPs+RS]. Current results exhibit that; HAP NPs induce a significant increase in myoglobin, LDH (lactate dehydrogenase), CK-MB (creatinine kinase) and CK (creatinine kinase) levels, cardiac thiobarbituric acid-reactive substances (TBARS), injury and P53 expressions. In contrast; a significant reduction in cardiac catalase, reduced glutathione (GSH) and superoxide dismutase (SOD) as compared to control group. Post treatment of rat with HAP NPs and rocket seeds extract (HAP NPs+RS) improved the cardiac functions and structure. Rocket seeds extract may offer advantages against the harmful effects of hydroxyapatite nanoparticles.

Combined actions of blueberry extract and lithium on neurochemical changes observed in an experimental model of mania: exploiting possible synergistic effects

Bipolar disorder is a psychiatric disease characterized by recurrent episodes of mania and depression. Blueberries contain bioactive compounds with important pharmacological effects such as neuroprotective and antioxidant actions. The aim of this study was to investigate the effects of blueberry extract and/or lithium on oxidative stress, and acetylcholinesterase (AChE) and Na⁺, K⁺-ATPase activity in an experimental ketamine-induced model of mania. Male Wistar rats were pretreated with vehicle, blueberry extract (200 mg/kg), and/or lithium (45 mg/kg or 22.5 mg/kg twice daily) for 14 days. Between the 8th and 14th days, the animals also received an injection of ketamine (25 mg/kg) or vehicle. On the 15th day the animals received a single injection of ketamine; after 30 min, the locomotor activity was evaluated in an open field test. Ketamine administration induced an increase in locomotor activity. In the cerebral cortex, hippocampus and striatum, ketamine also induced an increase in reactive oxygen species, lipid peroxidation and nitrite levels, as well a decrease in antioxidant enzyme activity. Pretreatment with blueberry extract or lithium was able to prevent this change. Ketamine increased the AChE and Na⁺, K⁺-ATPase activity in brain structures, while the blueberry extract partially prevented these alterations. In addition, our results showed that the neuroprotective effect was not potentiated when lithium and blueberry extract treatment were given together. In conclusion, our findings suggest that blueberry extract has a neuroprotective effect against an experimental model of mania. However, more studies should be performed to evaluate its effects as an adjuvant therapy.

In vitro exposure to fullerene C(60) influences redox state and lipid peroxidation in brain and gills from Cyprinus carpio (Cyprinidae)

Studies concerning the impact of nanomaterials, especially fullerene (C(60) ), in fresh water environments and their effects on the physiology of aquatic organisms are still scarce and conflicting. We aimed to assess in vitro effects of fullerene in brain and gill homogenates of carp Cyprinus carpio, evaluating redox parameters. A fullerene suspension was prepared by continued stirring under fluorescent light during two months. The suspension concentration was measured by total carbon content and ultraviolet-visible spectroscopy nephelometry. Characterization of C(60) aggregates was performed with an enhanced dark-field microscopy system and transmission electronic microscopy. Organ homogenates were exposed during 1, 2, and 4 h under fluorescent light. Redox parameters evaluated were reduced glutathione and oxidized glutathione, cysteine and cystine, total antioxidant capacity; activity of the antioxidant enzymes glutathione S-transferase and glutathione reductase (GR), and lipid peroxidation (TBARS assay). Fullerene induced a significant increase (p < 0.05) in lipid peroxidation after 2 h in both organs and reduced GR activity after 1 h (gills) and 4 h (brain) and antioxidant capacity after 4 h (brain). Levels of oxidized glutathione increased in the brain at 1 h and decreased at 2 h as well. Given these results, it can be concluded that C(60) can induce redox disruption via thiol/disulfide pathway, leading to oxidative damage (higher TBARS values) and loss of antioxidant competence.

Toxicity and glutathione implication in the effects observed by exposure of the liver fish cell line PLHC-1 to pure cylindrospermopsin

Cylindrospermopsin (CYN), a cyanotoxin produced by several freshwater cyanobacteria species, has been reported to cause human and animal intoxications. CYN is a potent inhibitor of protein and glutathione synthesis. In order to study these effects, various in vitro models have been used, which are representative of the organs targeted by the toxin. However, studies concerning CYN toxicity to fish species, both in vivo and in vitro, are still very scarce. To our knowledge, this is the first work dealing with the effects of CYN in a fish cell line. In the present work, we tried to test the hypothesis that CYN could be hepatotoxic to fish causing cell damage and oxidative stress, which may lead to pathogenicity. To deal this purpose, PLCH-1 cells, derived from fish liver, were exposed to concentrations that ranged from 0.3 to 40 μg/mL CYN during 24 and 48 h for the cytotoxicity study, and 2, 4 and 8 μg/mL CYN for the oxidative stress assays. The basal cytotoxicity endpoints studied were protein content, neutral red uptake and the tetrazolium salt, MTS, reduction. The biomarkers used for the oxidative stress study were reactive oxygen species (ROS) content, reduced glutathione content and γ-glutamylcysteine synthetase activity. The cytotoxicity endpoints revealed a decrease in the cellular viability in a time and concentration-dependent way. Moreover, when cells were exposed to pure CYN, an increase in the ROS content was observed, being more marked at the higher concentrations used. Finally, the present work shows alterations in GSH content and synthesis due to CYN. Moreover, a relationship between cytotoxic effects and ROS production has been evidenced. The results obtained confirm the alteration on fish liver cells, which should be considered relevant to what it may happen in real scenarios since fish are frequently in contact with this cyanotoxin.

Antioxidant activity of mojabanchromanol, a novel chromene, isolated from brown alga Sargassum siliquastrum

Silica gel chromatography HPLC, El-Mass, and NMR analyses were performed in order to determine the structure obtained from the separation and refinement of the main components of an ethanol extraction of Sargassum siliquastrum, which indicated its antioxidant activity An ethanol extraction of Sargassum siliquastrum demonstrated the strongest antioxidant activities of ethyl acetate when isolated by silica gel chromatography This amounts to 84.9 +/- 1.2% of its 0.5 mg ml(-1) concentration. The thiobarbituric acid reactive substances (TBARS) measurements from 3 isolations of an HPLC separation of ethyl acetate showed that the antioxidant activity of peak 2 was the most dominant at 84.08% in a 0.5 mg ml(-1) concentration. Peak 2 was verified as a type of chromene through El-Mass and NMR analysis. Its metal sealing characteristic was low while its characteristic of TBARS and DPPH erasure indicated similar or higher levels of metal sealing characteristic. The NMR spectroscopic data was used to elucidate the structure of this new compound, which showed strong antioxidant activity in the assay.

Effect of increased magnesium intake on plasma cholesterol, triglyceride and oxidative stress in alloxan-diabetic rats

Cardiovascular disorders are the primary causes of morbidity and mortality in patients with diabetes mellitus (DM). Agents that improve lipid profile and reduce oxidative stress have been shown to reduce the ensuing risk factors. In the present study, we investigated whether increased magnesium intake could improve hyperglycaemia, dyslipidaemia, and reduce oxidative stress in alloxan-induced diabetic rats. Male Wistar rats were divided into non-diabetic (ND), diabetic (DM) and diabetic fed on a high magnesium diet (DM-Mg) groups. Plasma concentrations of thiobarbituric acid reactive substances (TBARS) were used as markers of oxidative stress. Plasma levels of ascorbic acid, magnesium and calcium were also determined. Diabetes was induced by injecting alloxan (100 mg/kg B.W). The fasting blood glucose levels were significantly lower in the DM-Mg rats than in the DM rats. Plasma total cholesterol, triglyceride, TBARS levels were significantly higher while plasma HDL-cholesterol, HDL-cholesterol/total cholesterol ratio, ascorbic acid levels were significantly lowered in DM rats compared with the ND rats. Increased intake of magnesium significantly abrogated these alterations. There were no significant differences in the plasma levels of magnesium and calcium between the DM and ND groups. However, plasma levels of magnesium but not calcium were significantly elevated in DM-Mg rats when compared with other groups. In conclusion, these results suggest that diet rich in magnesium could exert cardioprotective effect through reduced plasma total cholesterol, triglyceride, oxidative stress and ameliorated HDL-cholesterol/total cholesterol ratio as well as increased plasma ascorbic acid and magnesium in diabetic rats.

[Effect of carvedilol on lipid peroxidation in patients with stable angina]

Effect of carvedilol on lipid peroxidation was investigated in patients with stable angina. The study comprised 30 patients (20 men and 10 women), aged 38-55 years (mean 48.3 years) with stable angina. The patients were administered carvedilol in increasing every four weeks doses: 12.5 mg/day, 25 mg/day, 50 mg/day. The control group consisted of 12 healthy subjects aged 39-49 years (mean 45.7 years). Blood samples were collected before and 4,8 and 12 weeks after therapy in patients and once in control group. Our study has been approved by the local Ethics Committee. MDA concentration in plasma and erythrocytes, which is a recognised indicator of tissue injury caused by reactive oxygen species, was measured according to Placer et al. MDA concentration was significantly higher (p < 0.05) in patients with stable angina than in control group. After 4, 8 and 12 weeks of carvedilol therapy, decrease in MDA concentration was observed in comparison to the initial values. MDA concentration did not differ in patients from that observed in healthy subjects after 8 and 12 weeks of therapy The results of our study have shown that carvedilol inhibits lipid peroxidation in patients with stable angina.

In vitro and in vivo antioxidant activity of ambroxol

In addition to a mucolytic action, ambroxol has antioxidant and anti-inflammatory properties. The antioxidant effects of ambroxol were studied both in vitro and in vivo. In vitro methods, such as (1) inhibition of hyaluronic acid degradation induced by hydroxy radicals and (2) standard lipid peroxidation assay in rat liver mitochondria and gastric mucosa, induced by tert-butyl hydroperoxide, were used. The in vivo approach was based on the study of the protective effect of pretreatment with ambroxol in a rat model of gastric corpus and antral lesions, induced by indomethacin. The inhibition of the degradation of hyaluronic acid was measured as a change of its viscosity; ambroxol (1,000 microl/l) reduced the degradation by 93%. Lipid peroxidation with tert-butyl hydroperoxide as a source of radicals was followed by the formation of thiobarbituric acid reactive substances. Ambroxol (10 mmol/l) inhibited lipid peroxidation by 96% in the rat liver mitochondria, and by 74% in the gastric mucosa. In vivo, ambroxol was administered p.o. at a dose of 10, 30, and 50 mg/kg, at 5, 30, and 60 min prior to indomethacin administration. The highest inhibition of the number of corpus gastric lesions and lowering of the lesion index (38% and 62%, respectively) was shown after the administration of 50 mg/kg, 30 min before indomethacin administration. Antral lesions were inhibited to a lesser extent by the same dose of ambroxol, administered 30 min before indomethacin treatment. Inhibition of the number of antral lesions reached 27% and the total area of the gastric damage was even larger (the ulcer index reached -5%).

Minimally modified LDL is an oxidized LDL enriched with oxidized phosphatidylcholines

The oxidative modification of low-density lipoprotein (LDL) is involved in atherogenesis. Among a variety of modified LDLs mentioned in the literature, so-called minimally modified LDL (MM-LDL) was reported to have pro-atherogenic properties despite minimal changes in its oxidative measures. After treatment of LDL with 1 micro M FeSO(4) at 4 degrees C for 96 h, the resulting MM-LDL showed a slight increase in thiobarbituric acid-reactive substances (TBARS) and little association with macrophages. On the other hand, heavily oxidized LDL, which was prepared by copper-induced oxidation of LDL at 37 degrees C, showed a sharp increase in TBARS and strong association with macrophages. By introducing a fluorometric procedure to detect aldehyde-containing phosphatidylcholines (aldehyde-PCs), we examined the amounts of aldehyde-PCs in modified LDL preparations. Aldehyde-PCs increased to 23.4 pmol/ microg protein in MM-LDL, which was more than four-fold higher than in the heavily oxidized LDL. We conclude that MM-LDL is a unique type of oxidized LDL enriched with aldehyde-PCs.

Inhibition of THP-1 cell-mediated low-density lipoprotein oxidation by the macrophage-synthesised pterin, 7,8-dihydroneopterin

Human macrophages release the pterin, 7,8-dihydroneopterin when exposed to the immune stimulant gamma-interferon (IFN-gamma). Previous in vitro studies have shown 7,8-dihydroneopterin is a potent antioxidant, which inhibits copper- and peroxyl-radical mediated low-density lipoprotein (LDL) oxidation. Using THP-1 cells, a human derived monocyte-like cell line, we have found that low micromolar concentrations of 7,8-dihydroneopterin inhibit cell mediated oxidation of LDL, as measured by electrophoretic mobility, alpha-tocopherol loss, and lipid oxidation. Stimulation of the THP-1 cells with IFN-gamma caused a significant reduction in the cells' ability to oxidise LDL. The extracellular pterin concentration increased from 0 to 16 nM with IFN-gamma stimulation, while the intracellular concentration increased from 0.21 to 1.69 nmol/mg cell protein.

Protection against cisplatin-induced nephrotoxicity by Cu(II)2(3,5-diisopropylsalicylate)4

The ability of Cu(II)(2)(3,5-diisopropylsalicylate)(4), CuDIPS, which exhibits superoxide dismutase (SOD)-like activity, to prevent cisplatin-induced nephrotoxicity was examined in rats. Rats were divided into four groups and treated as follows: (i) vehicle control; (ii) cisplatin (16 mg/kg, intraperitoneally); (iii) CuDIPS (10 mg/kg, intraperitoneally); and (iv) cisplatin plus CuDIPS. Rats were sacrificed 3 days post-treatment. Cisplatin alone resulted in significantly increased plasma creatinine and urea. Administration of 10 mg/kg CuDIPS prevented the cisplatin-induced elevation of plasma creatinine and urea and protected against kidney damage. Relative to controls, rats that received cisplatin treatment displayed a decrease of reduced glutathione (GSH) and elevated platinum and thiobarbituric acid reactive substances (TBARS) levels in the kidney. In comparison with controls, activities of antioxidant enzymes (SOD, CAT, GSH-Px and GSH-Rd) were also reduced in the kidney of rats treated with cisplatin. Administration of 10 mg/kg CuDIPS prevented cisplatin-induced alterations in renal platinum, GSH, TBARS, and antioxidant enzyme activities. This study suggests that the protection offered by CuDIPS against cisplatin-induced nephrotoxicity is partly related to maintenance of renal antioxidant systems.

Homocysteine strongly enhances metal-catalyzed LDL oxidation in the presence of cystine and cysteine

Here we show that homocysteine stimulates low density lipoprotein (LDL) oxidation at copper(II) concentrations causing only a slight oxidation of LDL lipids. LDL oxidation by homocysteine and copper(II) is further enhanced in the presence of cystine, although cystine alone does not stimulate LDL oxidation with copper(II). Similarly, a combination of cysteine with homocysteine provoked a more than additive increase of oxidation. Simultaneous presence of cysteine and homocystine also resulted in a more than additive oxidative effect which was not statistically significant, however. Stimulation of LDL oxidation in the presence of homocysteine by cystine was also observed with iron(III) at acidic pH and when LDL oxidation was initiated by azo-compound generated peroxyl radicals. At pH 7.4 histidine is able to prevent LDL oxidation by copper(II) in a thiol mixture similar to the one found in human plasma if present in tenfold excess over homocysteine, but loses its inhibitory effect at higher homocysteine concentrations. The synergistic effect on metal-catalyzed LDL oxidation observed with mixtures of homocysteine and cystine or cysteine sustains the hypothesis that the epidemiological association between raised homocysteine levels and risk of cardiovascular disease is caused by an increase in oxidative stress.

Ceramide increases oxidative damage due to inhibition of catalase by caspase-3-dependent proteolysis in HL-60 cell apoptosis

We investigated through which mechanisms ceramide increased oxidative damage to induce leukemia HL-60 cell apoptosis. When 5 microm N-acetylsphingosine (C(2)-ceramide) or 20 microm H(2)O(2) alone induced little increase of reactive oxygen species (ROS) generation as judged by the 2'-7'-dichlorofluorescin diacetate method, 20 microm H(2)O(2) enhanced oxidative damage as judged by ROS accumulation, and thiobarbituric acid-reactive substance production after pretreatment with 5 microm C(2)-ceramide at least for 12 h. The treatment with a catalase inhibitor, 3-amino-1h-1,2,4-triazole, increased oxidative damage and apoptosis induced by H(2)O(2), and in contrast, purified catalase inhibited the enhancement of oxidative damage by H(2)O(2) in ceramide-pretreated cells, suggesting that the oxidative effect of ceramide is involved in catalase regulation. Indeed, C(2)-ceramide inhibited the activity of immunoprecipitated catalase and decreased the levels of catalase protein in a time-dependent manner. Moreover, acetyl-Asp-Met-Gln-Asp-aldehyde, which dominantly inhibited caspase-3 and blocked the increase of oxidative damage and apoptosis due to C(2)-ceramide-induced catalase depletion at protein and activity levels. In vitro, active and purified caspase-3, but not caspase-6, -8, and -9, inhibited catalase activity and induced the proteolysis of catalase protein whereas these in vitro effects of caspase-3 were blocked by acetyl-Asp-Met-Gln-Asp-aldehyde. Taken together, it is suggested that H(2)O(2) enhances apoptosis in ceramide-pretreated cells, because ceramide increases oxidative damage by inhibition of ROS scavenging ability through caspase-3-dependent proteolysis of catalase.

Effects of N-(2-mercaptopropionyl)-glycine on mitochondrial function in ischemic-reperfused heart

OBJECTIVE

A possible mechanism for N-(2-mercaptopropionyl)-glycine (MPG) underlying the improvement of contractile function and mitochondrial activity of ischemic-reperfused rat hearts was examined.

METHODS

Isolated, perfused hearts were subjected to 35 min ischemia-60 min reperfusion. At the end of ischemia or reperfusion, myocardial Na(+) content and mitochondrial oxygen consumption rate (OCR) were examined. The perfused heart was treated with 0.1-1 mM MPG for 30 min prior to ischemia or for the first 30 min of reperfusion.

RESULTS

Ischemia increased myocardial Na(+) content (sodium overload) and decreased mitochondrial OCR. The left ventricular developed pressure (LVDP) of the untreated heart recovered to 19.8+/-3.8% of the preischemic value and the infarct area amounted to 23.3+/-1.7% of the left ventricle. The thiobarbiturate-reacting substance (TRS) was also increased in the reperfused, but not ischemic, myocardium. Pretreatment of the perfused heart with 0.3-1 mM MPG attenuated the ischemia-induced sodium overload and decrease in the OCR. Pretreatment with the agent also enhanced the postischemic recovery of LVDP, attenuated reperfusion-induced increase in TRS, and reduced the infarct area. Although the postischemic treatment with MPG suppressed the increase in TRS in the reperfused myocardium, a LVDP recovery of reperfused hearts was not observed. Cardiac mitochondria were isolated and examined for the direct effect of MPG on their function. Incubation with either 12.5 mM sodium lactate or 1 microM phenylarsine oxide neither altered the mitochondrial membrane potential nor induced mitochondrial swelling, whereas incubation with a combination of these agents elicited the membrane potential depolarization and swelling. Incubation of mitochondria with 1 mM MPG attenuated these events.

CONCLUSION

These results suggest that both attenuation of sodium overload and preservation of the mitochondrial function may largely contribute to cardioprotection of MPG in the ischemic-reperfused heart.

Potent modification of low density lipoprotein by group X secretory phospholipase A2 is linked to macrophage foam cell formation

The deposition of cholesterol ester within foam cells of the artery wall is fundamental to the pathogenesis of atherosclerosis. Modifications of low density lipoprotein (LDL), such as oxidation, are prerequisite events for the formation of foam cells. We demonstrate here that group X secretory phospholipase A2 (sPLA2-X) may be involved in this process. sPLA2-X was found to induce potent hydrolysis of phosphatidylcholine in LDL leading to the production of large amounts of unsaturated fatty acids and lysophosphatidylcholine (lyso-PC), which contrasted with little, if any, lipolytic modification of LDL by the classic types of group IB and IIA secretory PLA2s. Treatment with sPLA2-X caused an increase in the negative charge of LDL with little modification of apolipoprotein B (apoB) in contrast to the excessive aggregation and fragmentation of apoB in oxidized LDL. The sPLA2-X-modified LDL was efficiently incorporated into macrophages to induce the accumulation of cellular cholesterol ester and the formation of non-membrane-bound lipid droplets in the cytoplasm, whereas the extensive accumulation of multilayered structures was found in the cytoplasm in oxidized LDL-treated macrophages. Immunohistochemical analysis revealed marked expression of sPLA2-X in foam cell lesions in the arterial intima of high fat-fed apolipoprotein E-deficient mice. These findings suggest that modification of LDL by sPLA2-X in the arterial vessels is one of the mechanisms responsible for the generation of atherogenic lipoprotein particles as well as the production of various lipid mediators, including unsaturated fatty acids and lyso-PC.

Antioxidant alpha-keto-carboxylate pyruvate protects low-density lipoprotein and atherogenic macrophages

Oxidative modification of low-density lipoprotein (oxLDL) plays a pathogenic role in atherogenesis. Classical antioxidants such as L-ascorbic acid can inhibit formation of oxLDL. Alpha-Keto-carboxylates such as pyruvate and congeners also display antioxidant properties in some cell-free and intact cell systems. We tested the hypothesis that pyruvate or alpha-keto-glutarate may function as antioxidants with respect to LDL incubated with 5 or 10 microM Cu2+ alone or in combination with THP-1-derived macrophages. alpha-Hydroxy-carboxylates (L-lactate), linear aliphatic monocarboxylates (acetate/caprylate) and L-ascorbic acid served as controls. The oxLDL formation was ascertained by electrophoretic mobility and oxLDL cytotoxicity was judged by macrophage viability and thiobarbituric acid reactive substances (TBARS) formation. Cu2+ alone was not cytotoxic but increased electrophoretic mobility of cell-free LDL, stimulating TBARS. Millimolar pyruvate, alpha-ketoglutarate, or micromolar L-ascorbic acid partially inhibited oxLDL formation, while alpha-hydroxy-carboxylate or the aliphatic mono-carboxylates had no measurable antioxidant properties in cell-free LDL. Co-culture of LDL with macrophages and Cu2+ augmented TBARS release and resulted in 95% macrophage death. Pyruvate improved macrophage viability with 5 microM Cu2+ up to 60%. L-Ascorbic acid (> or = 100 microM) protected macrophages up to 80%. When > or = 100 microM L-ascorbic acid was combined with pyruvate, oxLDL formation and macrophage death were fully prevented. Thus, alpha-keto-carboxylates, but not physiological alpha-hydroxy-carboxylates or aliphatic monocarboxylates qualify as antioxidants in LDL systems. Since alpha-keto-carboxylates enhanced the antioxidant power of L-ascorbic acid, our findings may have implications for strategies attenuating atherosclerosis.

Role of antioxidant systems in induced nutritional pancreatic atrophy in chicken

One-day-old chicks were reared using diets differing in their vitamin E and/or selenium content. The purpose of this research was to detect any possible imbalance in the antioxidant defense system, which could be related to development of nutritional pancreatic atrophy. Mitochondrial membranes from animals deficient in both nutrients, or just vitamin E, submitted to peroxidizability 'in vitro' had the production of TBARS greatly enhanced. Measurements of the 2-GSH/GSSG ratio suggested that selenium and vitamin E, the latter in higher magnitude, were responsible for maintenance of the reducing capacity of the cell. Enzymatic defense systems against oxidative stress were also studied. The results indicated that the total antioxidant enzymatic activity of pancreatic cells was not sufficient to scavenge all the ROS generated in the nutritionally deficient animals. The present study suggests that nutritional deficiency of selenium and/or vitamin E generates one imbalance between pro-oxidant and antioxidant systems in chicken pancreas, leading to oxidative stress and pancreatic atrophy.

Oxidized low density lipoprotein inhibits prostacyclin generation by rat aorta in vitro: a key role of lysolecithin

The objective of this study was to examine the effect of oxLDL on prostacyclin (PGI2) generation by rat aortic segments and to see whether the lipid fraction of oxLDL or its components are responsible for that effect. We also tested if antioxidants have any protective role. LDL oxidized by copper was characterized by higher TBARS, conjugated diene, lysophosphatidylcholine (lyso PC), oxysterols and less polyunsaturated fatty acids (PUFA) than nLDL. Preincubation of aortas with oxLDL caused a significant inhibition of PGI2 generation compared to aortas preincubated with nLDL or buffer only. The percent inhibition was dependent on the concentration of oxLDL. Most of the inhibitory effect of oxLDL resided in its lipid moiety while the lipid fraction of nLDL, as well as native LDL had no effect. Preincubation of aortas with 10 microg/ml of 7-ketocholesterol the major oxysterol in oxLDL reduced the amount of PGI2 generated by aorta at all times tested; however that decrease did not reach a significant level. Aortas preincubated with 10 microg/ml of lyso PC showed a 21-36% inhibition of PGI2 generation which was comparable to the inhibition produced by preincubating the aortas with 50 microg protein/ml of oxLDL (containing about 7.5 microg lyso PC). This indicated that most of the inhibitory effect of oxLDL was due to its lyso PC. The small molecular weight fraction (< 10 kDa) with a high level of TBARS (TBARS solution) also significantly decreased the PGI2 generation by aorta. Addition of superoxide dismutase (SOD) + catalase or vitamin E simultaneously with oxLDL or TBARS solution in the preincubation medium did not reverse their inhibitory effects. This indicated that oxygen free radicals are not a contributing factor to the inhibitory effect of oxLDL but lyso PC and the lipid peroxides and probably other components already present within oxLDL are the important inhibitors.

A simple and sensitive method in using the ratios of cholesteryl ester molecular species as indexes of oxidative stress in plasma and lipoprotein fractions

To develop a simpler method for lipid peroxidation which may replace the classic gold standard of measuring the loss of polyunsaturated fatty acids, we investigated the use of ratios of molecular species of neutral lipids (MSNL) separated by gas chromatography in a single step. We sub-fractionated lipoproteins and subjected each to oxidation. Among different combinations of ratios of MSNL, we found that the ratios of cholesteryl esters (CE) containing C20/C16 (R1) and C18/C16 (R2) decreased most rapidly with increasing Cu2+ concentration and with increasing oxidation time, for all lipoproteins. We suggest that these two CE ratios can be used as oxidative indexes for all lipoproteins and thus for intact plasma. Experimental evidence showed that the oxidative index of whole plasma is the weighted average index of its lipoproteins. This method was validated with thiobarbituric acid method. Normal healthy asymptomatic males had R1 value 0.496 +/- 0.130, and R2 4.674 +/- 0.848, and females had R1 0.535 +/- 0.117 and R2 4.569 +/- 0.733 with no significant gender differences. Both ratios showed low variabilities within each individual. The method was tested to be feasible in monitoring vitamin E supplementation study. This CE-ratio method is concentration independent. It is simple, rapid, and highly reproducible, and, suitable for screening plasma on large scale.

Toxic reactions of oxidized LDL on cells of acute myeloid leukemia

In AML patients LDL concentration of the serum is reduced due to the high LDL receptor activity of the AML cells. This phenomenon enables the use of LDL particles as vehicles for drug targeting. Toxic lipid peroxides and aldehydes were introduced into LDL particles by the simple but effective oxidation with 10 microM CuSO4. Up to 250 nmol peroxides and 6 nmol malondialdehyde were formed per mg LDL protein within 30 h of oxidation. This oxidized LDL is effectively taken up by AML cells of the FAB type M3 and M5 indicating the presence of scavenger receptors on these cells. Within 96 h 61-84% of the AML cells are killed by the oxidized LDL. Our results open a possibility to achieve specificity for targeting lipophilic antineoplastic drugs towards AML cells using oxidized LDL as vehicles. The use of oxidized LDL as drug carrier is recommended for purging of AML bone marrow because hematopoietic stem cells that don't possess scavenger receptors are protected from toxic action.

Hypochlorite-induced peroxidation of egg yolk phosphatidylcholine is mediated by hydroperoxides

Using a chemiluminescent method, the consumption of HOCl/OCl- was investigated during interaction with liposomes prepared from dimyristoylphosphatidylcholine (DMPC) or egg yolk phosphatidylcholine (EYPC). The concentration of HOCl/OCl-decreased with time in the suspension of EYPC that contain unsaturated lipids and did not change in DMPC liposome suspensions. HOCl/OCl- was consumed more rapidly in peroxidized EYPC. The amount of double bonds was lowered by 40% in peroxidized liposomes and decreased by approximately one-third under the action of HOCl/OCl- in both native and peroxidized EYPC samples. Second-order rate constants for the interaction between HOCl and phospholipid double bonds of 0.50 M-1 s-1 were calculated for native EYPC on basis of the consumption of HOCl/OCl- or from the decrease in concentration of double bonds. In peroxidized EYPC this reaction constant was similar as determined following changes in double bonds. It is concluded that the consumption of HOCl/OCl- increased in peroxidized liposomes due to additional reactions with lipid peroxidation products. tert-Butyl hydroperoxide and cumene hydroperoxide, or organic peroxides or epoxides (cis-9,10-epoxystearic acid; cholesterol-5 alpha,6 alpha-epoxide; trans-2,3-epoxy-butane; cis-2,3-epoxy-butane) were incorporated into liposomes and investigated in respect to their ability (1) to increase the consumption of HOCl/OCl- in DMPC liposomes, (2) to generate a non-enhanced chemiluminescence with HOCl/OCl- and (3) to evoke an accumulation of lipid peroxidation products (TBARS) in EYPC liposomes in the absence and presence of NaOCl. None of peroxides or epoxides tested showed any effect on the consumption of HOCl/OCl- or the generation of chemiluminescence. Nor increase of TBARS both in the absence or presence of HOCl/OCl-. In contrast, tert-butyl hydroperoxide and cumene hydroperoxide increased the consumption of HOCl/OCl- in DMPC liposomes and mediated a higher accumulation of TBARS in EYPC liposomes in the presence of HOCl/OCL- over the control. These data suggest that lipid peroxidation in EYPC can be initiated by the reaction of HOCl/OCL- with organic hydroperoxides.

Inhibitory effect of lipid hydroperoxide on cholesteryl esterases

The oral supplement of air-oxidized linoleate hydroperoxide (LHPO) given in a small quantity to rats resulted in an increase in lipid peroxides (LPO) in the plasma and liver, together with the formation of an oxidatively modified low-density lipoprotein (LDL) with a high content of conjugated diene. Both acid and neutral cholesteryl esterases (CEases) were significantly suppressed in mononuclear leukocytes (MNL), liver, and aorta of the LHPO fed-rats. Significant inverse correlation coefficients were observed between two CEases activities and plasma LPO levels. The LDL isolated from the LHPO fed-rats inhibited in vitro both acid and neutral activities most efficiently among LDL derived from the experimental groups and confirmed in vivo oxidative inactivation of the intracellular CEases, possibly by lipid hydroperoxides in LDL through its increased uptake by the cells.

The interactions of modified lipoproteins with human erythrocyte membranes

The interactions of native and modified lipoproteins with erythrocyte membranes were studied via electron paramagnetic resonance (EPR). The in vitro incubation of minimally oxidized and glycated low density lipoprotein (LDL) with erythrocyte membranes of normal subjects induced a slight rigidification of the membrane lipids. The glycated LDL also caused alterations in conformation of normal and diabetic erythrocyte membrane proteins. In contrast both oxidized and glycated high density lipoprotein (HDL) caused no significant changes in the organization of membranes. These, new findings suggest that the modified LDL may influence the structure of erythrocyte membrane components.

Oxidative modification of low-density lipoproteins by mesangial cells

Because hypercholesterolemia and mesangial cell proliferation may be important in the pathogenesis of glomerulosclerosis, the effects of low-density lipoprotein (LDL) on human mesangial cell proliferation were evaluated. Native LDL (20 to 200 micrograms/mL) caused a dose-dependent increase in (3H)thymidine incorporation and increased mesangial cell numbers over 96 h. The mitogenic effect of LDL was partially blocked by the inhibition of cytochrome P-450, but not by the inhibition of cyclooxygenase or lipoxygenase pathways. Higher LDL concentrations (1,000 to 2,000 micrograms/mL) inhibited (3H)thymidine incorporation and reduced cell numbers, possibly as a result of the oxidative modification of LDL, indicated by an increase in thiobarbituric reactive substances. This peroxidation of LDL involved superoxide, because superoxide dismutase and butylated hydroxytoluene prevented it, whereas hydroxyl radical scavengers were without effect. Native LDL subjected to chemical oxidation by copper sulfate also inhibited mesangial cell proliferation. These results suggest that low concentrations of LDL may stimulate human mesangial cell proliferation, which may, in turn, cause the production of reactive oxygen molecules. Moreover, the oxidative modification of LDL may mediate the toxic effects of high LDL concentrations on human mesangial cells.