Model systems for studying lipid oxidation associated with muscle foods: Methods, challenges, and prospects

Lipid oxidation is a complex process in muscle-based foods (red meat, poultry and fish) causing severe quality deterioration, e.g., off-odors, discoloration, texture defects and nutritional loss. The complexity of muscle tissue -both composition and structure- poses as a formidable challenge in directly clarifying the mechanisms of lipid oxidation in muscle-based foods. Therefore, different in vitro model systems simulating different aspects of muscle have been used to study the pathways of lipid oxidation. In this review, we discuss the principle, preparation, implementation as well as advantages and disadvantages of seven commonly-studied model systems that mimic either compositional or structural aspects of actual meat: emulsions, fatty acid micelles, liposomes, microsomes, erythrocytes, washed muscle mince, and muscle homogenates. Furthermore, we evaluate the prospects of stem cells, tissue cultures and three-dimensional printing for future model system development. Based on this reviewing of oxidation models, tailoring correct model to different study aims could be facilitated, and readers are becoming acquainted with advantages and shortcomings. In addition, insight into recent technology developments, e.g., stem cell- and tissue-cultures as well as three-dimensional printing could provide new opportunities to overcome the current bottlenecks of lipid oxidation studies in muscle.

Eryptosis is an indicator of hematotoxicity in the risk assessment of environmental amorphous silica nanoparticles exposure: The role of macromolecule corona

Silica nanoparticles (SiO₂ NPs) have been widely manufactured for various applications and unintentionally generated in various industrial processes. SiO₂ NPs exposure is potentially hazardous to human health. Incremental evidence has indicated the presence of SiO₂ NPs in systemic circulation, which warranted their interaction with blood components. Due to the obvious weakness of hemolysis in the risk assessment of environmental NPs, we for the first time use eryptosis as a sensitive indicator to assess the hematotoxicity of SiO₂ NPs. In vitro results showed that the exposure of erythrocytes to pristine SiO₂ NPs resulted in typical features of eryptosis, including oxidative stress, calcium influx, phosphatidylserine externalization and hemolysis. However, SiO₂ NPs covered with mouse plasma (SiO₂@MP) or grafted with polyvinylpyrrolidone (SiO₂@PVP) did not stimulate eryptosis. Interestingly, neither bare nor macromolecule-decolorated SiO₂ NPs caused eryptosis in our in vivo mouse model, highlighting the protective role of coronal proteins on the amelioration of SiO₂ NPs-induced hematotoxicity. These results emphasized the influences of surface modification on the toxicity of environmental NPs.

Band 3 protein function and oxidative stress in erythrocytes

Band 3 protein (B3p), anion transporter, allows the HCO₃ ^- /Cl^- exchange across plasma membrane and plays an important role for erythrocytes homeostasis. In addition, B3p is linked to proteins cytoskeleton, thus contributing to cell shape and deformability, essential to erythrocytes adjustment within narrowest capillaries. Taking into account that erythrocytes are a suitable cell model to investigate the response of the oxidative stress effects, B3p functions, and specifically anion exchange capability, determining the rate constant for SO₄ ^2- uptake, has been considered. As, in the latter years, rising attention has been addressed to membrane transport system, and particularly to this protein, the present mini-review has been conceived to report the most recent knowledge about B3p, with specific regard to its functions in oxidative stress conditions, including oxidative stress-related diseases.

Plasma from Young Rats Injected into Old Rats Induce Antiaging Effects

An experimental novel antiaging intervention strategy is based on the concept of parabiosis, which involves long-term treatment with factors derived from young blood facilitating rejuvenation of old individuals. In this study, we employed blood plasma from young rats as an intervention strategy to evaluate whether this could impact aging biomarkers in aged rats. The biomarkers studied include: reactive oxygen species, the ferric reducing ability of plasma, plasma membrane redox system, reduced glutathione, malondialdehyde, protein carbonyl, and advanced oxidation protein products in blood. Additionally, the level of tumor necrosis factor-α and interleukin-6 were also estimated in blood. We found that old rats injected with plasma from young rats were protected from oxidative stress. Thus, this study provides some evidence of the rejuvenating effects of young plasma. We hypothesize that young plasma may contain certain "factors," which may be responsible for the observed effects. The mechanism of action is not clearly understood and is open to further studies.

Exposure to organic solvents and hepatotoxicity

The purpose of this study was to identify the long-term effect of chemical exposure on the liver. Laboratory tests included alanine aminotransferase (ALT) dosage and oxidative stress tests, such as thiobarbituric acid reactive substances in plasma and superoxide dismutase (SOD) and glutathione S-transferase analysis in erythrocytes. The cross-sectional study comprised 70 workers, 30 of them exposed to organic solvents and 40 not exposed. All those exposed presented at least 5 years of exposure to solvents. Hepatitis B and C, known hepatic disease, comorbidities, use of alcohol, illicit drugs or hepatotoxic medications, smoking, body mass index >30, female sex and age (<18 or >65) were excluded from the sample. Results indicated that elevated ALT was more frequent in the exposed group compared to controls: 33% vs. 10.5%, with a statistical significance (p < 0.05). Thiobarbituric acid reactive substances were significantly elevated (p < 0.01) in the exposed group in comparison to controls. Antioxidant enzymes were more elevated in the exposed group compared to controls: SOD 7.29 (4.30-8.91) USOD/mg of protein vs. 3.48 (2.98-5.28) USOD/mg of protein and GST 2.57 µmol/min/mg of protein (1.80-4.78) vs. 1.81 µmol/min/mg of protein (1.45- 2.30) µM/min/mg of protein. The results suggest an association between exposure to organic solvents and hepatotoxicity.

Effects of Acute Toluene Toxicity on Different Regions of Rabbit Brain

The acute phase effects of toluene on the brain have been investigated in this study using rabbit brain via histopathological, immunohistochemical, and biochemical methods. A total of 20 male rabbits were used as control and experimental groups. Moreover, nerve growth factor (NGF), tumor necrosis factor-alpha (TNF-alpha), dopamine (DA), and glial fibrillary acidic protein (GFAP) tests were performed in order to designate the severity of the biochemical damage. In the biochemical evaluation of the prefrontal cortex, hippocampus, hypothalamus, substantia nigra, and entorhinal cortex, the TNF-alpha levels in the brain were found to be significantly higher than in the control group. Levels of dopamine, secreted from the substantia nigra, nerve growth factor (NGF) developed from the hippocampal neurons, and GFAP, secreted from astrocyte cells, were detected to be significantly lower in the toluene-administration group than in the control group (p < 0.05). In addition, areas of focal vacuolar degeneration (abscess formation), gliosis, and perivascular demyelination, many pyknotic cells and necrosis were observed. In the toluene-administration group compared to the control group, distinct excessive expansions of the blood vessels and severe degeneration in the structure of cells and also dispersed cell borders were observed. Furthermore, abnormal malformations of the nuclei structure of the oligodendrocyte cells were seen. Bodies of the sequential neurons of the hippocampus in the toluene-administration group were distinctly structurally damaged compared to the control group. In addition, cytoplasm of the cortex cell showed serious immune reactivity in the experimental group.

Naringin mitigates erythrocytes aging induced by paclitaxel: an in vitro study

In this study, the protective role of naringin (NAR) against paclitaxel (PTX)-induced erythrocytes aging has been investigated using human erythrocyte as an in vitro model. Erythrocytes were incubated with PTX in the presence and absence of NAR. Incubation of erythrocytes with PTX resulted in increased protein carbonyl content and malondialdehyde and hemolysis percentage compared with control. Furthermore, a significant increase in the ratios of glutathione peroxidase/glutathione reductase, superoxide dismutase/glutathione peroxidase, and superoxide dismutase/catalase in PTX-treated cells was observed, compared with control cells. In contrast, reduced glutathione/oxidized glutathione ratio and glucose-6-phosphate dehydrogenase activity were decreased upon PTX treatment. The simultaneous incubation of erythrocytes with PTX and NAR restored these variables to values similar to those of control erythrocytes. These results suggest that NAR inhibited PTX-induced aging by lessening the PTX-induced oxidative stress.

Oxidative stress effects of thinner inhalation

Thinners are chemical mixtures used as industrial solvents. Humans can come into contact with thinner by occupational exposure or by intentional inhalation abuse. Thinner sniffing causes damage to the brain, kidney, liver, lung, and reproductive system. We discuss some proposed mechanism by which thinner induces damage. Recently, the induction of oxidative stress has been suggested as a possible mechanism of damage. This paper reviews the current evidence for oxidative stress effects induced by thinner inhalation. Early ideas about the effects of thinner on lipids are discussed in one section. We discuss several studies that have shown the oxidative effects of thinner inhalation on: lipid peroxidation, levels of antioxidant enzymes, glutathione depletion, and oxidation of proteins and DNA. We have also included studies about oxidative stress effects induced by toluene, the principal component (60-70%) of thinner. Finally, work describing the effects of oxidative stress induced by thinner inhalation on different organs is discussed.

In vitro and in vivo evaluation of a primaquine prodrug without red blood cell membrane destabilization property

Primaquine is an important therapeutic resource for malaria treatment and it has wide activity against several pathogens. The haematotoxicity of primaquine is the major problem for its therapeutic application. This effect is aggravated by repeated use at high doses and by the wide fluctuation of plasma levels after administration. The primaquine prodrug (Phe-Ala-PQ) was planned in order to modify the pharmacokinetics and toxicity of primaquine. The in vitro conversion of Phe-Ala-PQ to primaquine, and the primaquine pharmacokinetics were evaluated in four groups of rats: two groups that received a single dose of Phe-Ala-PQ, one by intravenous and the other by gavage route, and two other groups that received primaquine diphosphate, by intravenous and gavage routes. In addition, the erythrocyte osmotic fragility was compared in two groups of rats that received multiple doses of primaquine diphosphate or Phe-Ala-PQ, as a parameter of haematotoxicity. The in vitro conversion of Phe-Ala-PQ to primaquine by plasma enzyme action was observed. The pharmacokinetic profile of primaquine from Phe-Ala-PQ was more favourable due to the lower fluctuation of plasma concentrations. Haematotoxicity was not evidenced in the prodrug administration. The results reinforce the need for further studies with this prodrug, promising an alternative in the therapeutic use of primaquine.

The apoptotic effect of a high dose of toluene on liver tissue during the acute phase: an experimental study

The aim of this study is to investigate the acute toxic effects of high-dose toluene and its mechanisms on the liver tissue of toluene-treated rats. In this study, 16 adult male Wistar albino rats (200–220 g) were divided into two equal groups. Group I was used as a control group, while group II was exposed to high dose of toluene, 5200 mg/kg (6 ml/kg per gavage). After the 3-hour experimental period, blood samples and liver tissues were taken from the euthanized animals. Serum aspartate and alanine aminotransferase levels were assayed. Liver tissues were fixed in 10% neutral formalin, then embedded in paraffin and sectioned (5 μm thickness). Sections were stained with hematoxylin and eosin for histopathological examination. A terminal transferase dUTP nick end labeling assay was also done for the determination of apoptosis in liver tissues. For the determination of Bax and caspase-3 immunoreactivity, the sections were stained using avidin–biotin–peroxidase immunohistochemical method. The level of plasma transaminase was found to be increased in toluene administered rats. Additionally, slight degeneration of hepatocyte and mononuclear cell infiltration was observed in the liver tissue sections and a high (+++) immunoreactivity for Bax and caspase-3 protein was observed in the toluene group. This study showed that the high dose of toluene triggers apoptosis in the liver of rats via the mitochondrial pathway in acute period.

HSP70 immune reactivity and TUNEL positivity in the liver of toluene-inhaled and melatonin-treated rats

Toluene is a clear, colorless and volatile hydrocarbon that is metabolized in liver, produced free oxygen radicals and can mediate cellular damage. Melatonin which is a pineal gland hormone is a very potent antioxidant. It can make the cellular membrane more durable against oxidative attacks and protect nuclear DNA from oxidative damage. This study aimed to investigate heat shock protein (HSP)70 immune reactivity and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) positivity (apoptotic activity) in the liver of toluene-inhaled and melatonin-treated rats. A total of 21 adult male Wistar albino rats were divided at random into 3 equal groups. Animals in group I were designated as control. The rats in group II were exposed to toluene (3000 ppm/1 h/day) for 30 days, while the rats in group III were treated with melatonin (10 mg/kg/day, intraperitoneally) plus toluene inhalation. At the end of the 30-day experimental period, all rats were killed by decapitation. Then the liver tissues of rats were removed and tissue specimens were embedded in paraffin blocks. The specimens were stained with periodic acid-schiff (PAS) following routine histological procedures. Sections obtained from paraffin blocks were used for immune detection of TUNEL and HSP70. In light microscopic observations of tissues from toluene-inhaled rats, massive hepatocyte degeneration, ballooning degeneration and decreased PAS positivity were observed. Increased TUNEL positivity and HSP70 immune reactivity were determined in toluene-inhaled group and melatonin treatment decreased all these adverse effects.

Gender effects of acute malathion or zinc exposure on the antioxidant response of rat hippocampus and cerebral cortex

Gender is one of the most important factors in mammalian development and response to exogenous agents. Although there is increasing evidence that health effects of toxic xenobiotics differ in prevalence or are manifested differently in male and female, the molecular mechanisms related to these events remain unclear. In order to investigate the possible influence of gender, male and female Wistar rats from the same litter were exposed to zinc chloride (5 mg/kg, i.p.) or malathion (250 mg/kg, i.p.) 24 hr prior to the analyses of biochemical parameters related to the cholinergic and glutathione-antioxidant systems in cerebral cortex and hippocampus. After treatments, acetylcholinesterase (AChE) activity was reduced in the hippocampus and cerebral cortex of male and female rats treated with malathion, but the effect was more pronounced in the male group. Glutathione reductase (GR) and γ-glutamyl-transpeptidase activities were reduced in the hippocampus of males and females and a gender-specific effect of malathion was seen for glutathione S-transferase (GST), which was decreased only in male hippocampus and cortex, and for male cortical GR. Zinc chloride treatment decreased AChE activity in male and female cerebral cortex, with no obvious effect in the hippocampus. Male-specific antioxidant-related enzyme activity reductions were seen after zinc treatment for cortical GR, GST, glutathione peroxidase and glucose-6-phosphate dehydrogenase; and hippocampal GR. These results clearly demonstrate a greater detrimental effect on antioxidant-related enzyme activities in male hippocampus and cerebral cortex when rats were acutely exposed to malathion and zinc, demonstrating that the research on gender-related differences in health effects caused by xenobiotic and/or essential elements requires further attention.

Hepatotoxic activity of toluene inhalation and protective role of melatonin

This study was designed to investigate the harmful effects of toluene inhalation in the liver of rats and possible protective effects of melatonin on these detrimental effects. For this purpose, 21 adult male Wistar-albino rats were randomly divided into three equal groups. Animals in group I were used as control. The rats in group II were exposed to toluene (3000 ppm/1 hour/day) for 4 weeks, while the rats in group III were treated with melatonin (10 mg/kg/day, intraperitoneally [ip]) plus toluene inhalation. At the end of the experimental period, liver and blood samples were taken from the decapitated animals. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin and albumin levels were determined. Liver tissue sections were stained with routine histological methods and examined under the light microscope. In addition, the sections were immunohistochemically stained using avidin-biotin-peroxidase method for determination of apoptosis. The liver tissue activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and malondialdehyde (MDA) levels were also measured. Toluene inhalation significantly increased serum ALT, AST and tissue MDA, and decreased serum albumin, but did not affect serum ALP, total bilirubin levels and tissue SOD, GSH-Px and CAT activity when compared with controls. The increases in tissue MDA and serum ALT and AST levels induced by toluene inhalation were significantly inhibited by melatonin treatment. In light microscopic observations of tissues from toluene-inhaled rats, massive hepatocyte degeneration, ballooning degeneration and mild pericentral fibrosis were observed. Bax immune reactivity was also increased significantly. Melatonin treatment decreased the balloon degeneration, fibrosis and Bax immune reactivity in the liver of toluene-inhaled rats. In view of the present findings, it is suggested that melatonin has hepatoprotective effects against toluene toxicity via primarily antioxidative properties.

Pravastatin provides antioxidant activity and protection of erythrocytes loaded Primaquine

Loading erythrocytes with Primaquine (PQ) is advantageous. However, PQ produces damage to erythrocytes through free radicals production. Statins have antioxidant action and are involved in protective effect against situation of oxidative stress. Thus the protective effect of pravastatin (PS) against PQ induced oxidative damage to human erythrocytes was investigated in the current studies upon loading to erythrocytes.The erythrocytes were classified into; control erythrocytes, erythrocytes incubated with either 2 mM of PS or 2 mM of PQ, and erythrocytes incubated with combination of PS plus PQ. After incubation for 30 min, the effect of the drugs on erythrocytes hemolysis as well as some biomarkers of oxidative stress (none protein thiols, protein carbonyl, thiobarbituric acid reactive substance) were investigated.Our results revealed that PS maintains these biomarkers at values similar to that of control ones. On the other hand, PQ cause significant increases of protein carbonyl by 115% and thiobarbituric acid reactive substance by 225% while non-protein thiols were significantly decreased by 112 % compared with control erythrocytes. PS pre-incubation before PQ exerts marked reduction of these markers in comparison with PQ alone. Moreover, at NaCl concentrations between 0.4% and 0.8%, PQ causes significant increase of Red Blood Cells (RBCs) hemolysis in comparison with the other groups (P<0. 001). Scanning electron micrograph indicates spherocytes formation by PQ incubation, but in the other groups the discocyte shape of erythrocytes was preserved.The reduction of protein oxidation and lipids peroxidation by PS is related to antioxidants effect of this statin. Preservation of erythrocytes fragility and morphology by PS are related to its free radicals scavenging effect. It is concluded that pravastatin has protective effect against erythrocytes dysfunction related any situations associated with increased oxidative stress, especially when loaded with PQ.

Markers of oxidative stress in erythrocytes and plasma during aging in humans

Aging is an inevitable universal biological process, which can be characterized by a general decline in physiological function with the accumulation of diverse adverse changes and increased probability of death. Among several theories, oxidative stress/free radical theory offers the best mechanistic elucidation of the aging process and other age -related phenomenon. In the present paper , we discuss the aging process and have focused on the importance of some reliable markers of oxidative stress which may be used as biomarkers of the aging process.