Zinc, antioxidant systems and metallothionein in metal mediated-apoptosis: biochemical and cytochemical aspects

Correlation Between Phytochemical and Mineral Contents and Antioxidant Activity of Black Glutinous Rice Bran, and Its Potential Chemopreventive Property

In this work total anthocyanin content (TAC), total flavonoid content (TFC), total phenolic content (TPC) and minerals found in five black glutinous rice cultivars (MS, SK, PY, PC and KK) from Thailand were analyzed. The antioxidant activity of anthocyanin-rich black glutinous rice bran extracts against nitric oxide radical (NO˙), superoxide radical (O₂˙Ż) and lipid peroxyl radical (LOO˙) was also determined. Potential chemopreventive property of rice bran extract was screened based on cellular bioassays for phase II detoxification enzyme induction. Quinone reductase (QR) induction in murine hepatoma cells was used as a marker for this effect. Rice bran extract of cultivar KK had the highest TAC, of SK the highest TFC and of PC the highest TPC. The best antioxidants against NO˙, O₂˙Ż and LOO˙ were cultivars KK, MS, and SK, respectively. Overall, TAC, TFC and TPC had a combinatorial effect on the antioxidant activities of all extracts; none of them dominated. Minerals may not play a role in the antioxidant activity of the extracts because most correlations between them and the antioxidant activity were unpredictable. However, rice bran contained high mass fractions of some essential minerals on dry mass basis, including Zn (103-133 µg/g), Se (11-18 µg/g) and Cu (3.8-7.1 µg/g). Chemopreventive study indicated that PC cultivar was the most potent chemopreventor with the lowest concentration of an inducer needed to double the QR activity (CD value) of 0.7 µg/mL. These findings showed that black glutinous rice bran is rich in phytochemicals and some essential minerals, and has a potential chemopreventive property.

Metallothionein and Glutathione Content as Biomarkers of Metal Pollution in Mussels and Local Fishermen in Abu Qir Bay, Egypt

BACKGROUND

When heavy metals accumulate in air, soil, and water, the risk of human exposure increases among industrial workers, as well as in people living near polluted areas. Heavy metals adversely affect a variety of bodily systems such as the cardiovascular, respiratory, endocrine, immune, and reproductive systems. In addition, long-term exposure and accumulation of heavy metals in the body may disturb oxidative stress genes and thus increase the susceptibility to various diseases.

OBJECTIVES

The aim of this study is to estimate the metallothionein concentration in both mussel samples from Abu Qir Bay, Egypt and the blood of local fishermen as a biomarker of exposure to metal pollution.

METHODS

Levels of metallothionein and heavy metals were measured in mussels. Blood levels of metallothionein and heavy metals of local fishermen were measured and compared with a control group. The effect of heavy metal exposure on oxidative stress status was investigated through the determination of malondialdehyde (MDA), catalase and glutathione content.

RESULTS

The results of this study showed high concentrations of metallothionein in mussels and in fishermen's blood, accompanied by high concentrations of metals such as cadmium (Cd), copper (Cu), lead (Pb), chromium (Cr), and zinc (Zn). At the same time, a significant decrease in glutathione content and catalase enzyme activity was associated with a significant increase in the malondialdehyde concentrations in sera of fishermen.

CONCLUSIONS

The present study found that the El Maadiya region is polluted with heavy metals, inducing oxidative stress in fishermen in the vicinity. These results reveal the necessity of further environmental monitoring in the study area in order to evaluate other types of pollutants and their effects on human health.

Investigation of lipid peroxidation and antiapoptotic effects of zinc aganist liver damage in diabetic rats

Several mechanisms for the pathogenesis of diabetic complications have been proposed, one of which is abnormal zinc (Zn) homeostasis. Zn is necessary for proper liver function since it has important antioxidant, anti-inflammatory, and antiapoptotic properties. We aimed to investigate whether or not Zn has morphologically protective effect on diabetes-induced liver damage in rats. In addition, we have investigated the role of Zn supplementation on apoptosis, lipid peroxidation levels, and the distribution of metallothionein (MT) in diabetic liver tissue. Wistar albino rats were divided into four groups: control, Zn, diabetic, and Zn-diabetic group. Experimental diabetes was induced by a single-dose streptozotocin intraperitoneally and Zn was administrated via gastric gavage tube for 6 weeks. MT expressions were showed with immunohistochemical staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used for apoptosis. Also, Zn, MT, and malondialdehyde (MDA) levels were determined in liver of rats. MDA levels of the Zn-supplemented diabetic group was less than the diabetic group though MT levels were increased. The number of apoptotic cells per unit area was found to be significantly decreased in this group. In the Zn-supplemented diabetic group, fibrotic tissue density and the collagen tissue density were observed less than the diabetic group. MT immunoreactivity was observed less in Zn-supplemented diabetic group. In conculusion, the present study indicated that Zn has a potential in preventing or even repairing effect against diabetic damage of the liver cells by increasing expression of MT and by reducing the apoptotic cell death and the oxidative stress.

Menkes disease: what a multidisciplinary approach can do

Disorders of copper homeostasis are currently recognized across the life span. Their recognition and links to human disease have spanned several decades, beginning with the recognition of a degenerative disorder in the offspring of sheep grazing in copper-deficient pastures, through to the description of infants suffering from a progressive neurodegenerative disorder characterized by epileptic seizures, developmental regression, failure to thrive, and an unusual hair quality (giving the condition its distinctive label of “kinky hair disease”). In this review, we trace the historical background and describe the biochemistry and physiology of copper metabolism and transport, inheritance patterns, molecular genetics, and genotype–phenotype correlations based on current understanding of the disorder. It is clear from the clinical presentations and variants that disorders of copper homeostasis include phenotypes ranging from mild occipital horn syndrome to intermediate and severe forms of classical Menkes disease. The symptoms involve multiple organ systems such as brain, lung, gastrointestinal tract, urinary tract, connective tissue, and skin. A multisystem disorder needs a multidisciplinary approach to care, as treatment interventions permit longer survival for some individuals. Animal models have been developed to help screen treatment options and provide a better understanding of these disorders in the laboratory. Finally, we propose a multidisciplinary approach to promote continued research (both basic and clinical) to improve survival, quality of life, and care for these conditions.

Differential genotoxicity mechanisms of silver nanoparticles and silver ions

In spite of many reports on the toxicity of silver nanoparticles (AgNPs), the mechanisms underlying the toxicity are far from clear. A key question is whether the observed toxicity comes from the silver ions (Ag⁺) released from the AgNPs or from the nanoparticles themselves. In this study, we explored the genotoxicity and the genotoxicity mechanisms of Ag⁺ and AgNPs. Human TK6 cells were treated with 5 nM AgNPs or silver nitrate (AgNO₃) to evaluate their genotoxicity and induction of oxidative stress. AgNPs and AgNO₃ induced cytotoxicity and genotoxicity in a similar range of concentrations (1.00-1.75 µg/ml) when evaluated using the micronucleus assay, and both induced oxidative stress by measuring the gene expression and reactive oxygen species in the treated cells. Addition of N-acetylcysteine (NAC, an Ag⁺ chelator) to the treatments significantly decreased genotoxicity of Ag⁺, but not AgNPs, while addition of Trolox (a free radical scavenger) to the treatment efficiently decreased the genotoxicity of both agents. In addition, the Ag⁺ released from the highest concentration of AgNPs used for the treatment was measured. Only 0.5 % of the AgNPs were ionized in the culture medium and the released silver ions were neither cytotoxic nor genotoxic at this concentration. Further analysis using electron spin resonance demonstrated that AgNPs produced hydroxyl radicals directly, while AgNO₃ did not. These results indicated that although both AgNPs and Ag⁺ can cause genotoxicity via oxidative stress, the mechanisms are different, and the nanoparticles, but not the released ions, mainly contribute to the genotoxicity of AgNPs.

Redox Reactivity of Cerium Oxide Nanoparticles Induces the Formation of Disulfide Bridges in Thiol-Containing Biomolecules

The redox state of disulfide bonds is implicated in many redox control systems, such as the cysteine-cystine couple. Among proteins, ubiquitous cysteine-rich metallothioneins possess thiolate metal binding groups susceptible to metal exchange in detoxification processes. CeO2 NPs are commonly used in various industrial applications due to their redox properties. These redox properties that enable dual oxidation states (Ce(IV)/Ce(III)) to exist at their surface may act as oxidants for biomolecules. The interaction among metallothioneins, cysteine, and CeO2 NPs was investigated through various biophysical approaches to shed light on the potential effects of the Ce(4+)/Ce(3+) redox system on the thiol groups of these biomolecules. The possible reaction mechanisms include the formation of a disulfide bridge/Ce(III) complex resulting from the interaction between Ce(IV) and the thiol groups, leading to metal unloading from the MTs, depending on their metal content and cluster type. The formation of stable Ce(3+) disulfide complexes has been demonstrated via their fluorescence properties. This work provides the first evidence of thiol concentration-dependent catalytic oxidation mechanisms between pristine CeO2 NPs and thiol-containing biomolecules.

Zinc-induced metallothionein overexpression prevents doxorubicin toxicity in cardiomyocytes by regulating the peroxiredoxins

1. Cardiotoxicity is an important factor that limits the clinical use of doxorubicin (Dox). Metallothionein (MT) can antagonize the Dox-induced cardiotoxicity. Using a proteomics approach we have detected that major peroxiredoxins (Prxs) may be involved in this process. In the present study, we further investigate the mechanisms of the MT effects against Dox-induced cytotoxicity and the interactions between MT and Prxs. 2. We have established a primary cardiomyocyte culture system from MT-I/II null (MT(-/-)) and corresponding wild type (MT(+/+)) neonatal mice, and pretreated the MT(+/+) cardiomyocytes with ZnCl2 to establish the MT overexpression cardiomyocyte model. 3. Based on the results, in MT(+/+) cardiomyocytes, ZnCl2 pretreatment significantly increased the cardiomyocytes MT levels and inhibited the cardiotoxicity of Dox; it can resist LDH leakage, cardiomyocyte apoptosis, DNA damage, ROS accumulation and inhibit the decrease in activity of antioxidant enzymes induced by Dox. Moreover, ZnCl2 enhanced the expression of Prx-2, -3, -5 and -6, it can inhibit the expression of Prxs decrease in MT(+/+) cardiomyocytes induced by Dox, but had no effect in MT(-/-) cardiomyocytes. 4. Therefore, the present study suggests that ZnCl2 can protect the cardiomyocytes from the Dox-induced oxidative injury and can inhibit the changes in Prxs expression through induced MT overexpression.

Antioxidant Intake and Antitumor Therapy: Toward Nutritional Recommendations for Optimal Results

The role of the induction of oxidative stress as the mechanism of action of many antitumor drugs is acquiring an increasing interest. In such cases, the antitumor therapy success may be conditioned by the antioxidants present in our own body, which can be synthesized de novo (endogenous) or incorporated through the diet and nutritional supplements (exogenous). In this paper, we have reviewed different aspects of antioxidants, including their classification, natural sources, importance in diet, consumption of nutritional supplements, and the impact of antioxidants on health. Moreover, we have focused especially on the study of the interaction between antioxidants and antitumor therapy, considering both radiotherapy and chemotherapy. In this regard, we found that the convenience of administration of antioxidants during cancer treatment still remains a very controversial issue. In general terms, antioxidants could promote or suppress the effectiveness of antitumor treatment and even protect healthy tissues against damage induced by oxidative stress. The effects may depend on many factors discussed in the paper. These factors should be taken into consideration in order to achieve precise nutritional recommendations for patients. The evidence at the moment suggests that the supplementation or restriction of exogenous antioxidants during cancer treatment, as appropriate, could contribute to improving its efficiency.

Serum Concentrations of Trace Elements in Patients with Tuberculosis and Its Association with Treatment Outcome

Deficiencies in essential trace elements are associated with impaired immunity in tuberculosis infection. However, the trace element concentrations in the serum of Korean patients with tuberculosis have not yet been investigated. This study aimed to compare the serum trace element concentrations of Korean adult patients with tuberculosis with noninfected controls and to assess the impact of serum trace element concentration on clinical outcome after antituberculosis treatment. The serum concentrations of four trace elements in 141 consecutively recruited patients with tuberculosis and 79 controls were analyzed by inductively coupled plasma-mass spectrometry. Demographic characteristics were also analyzed. Serum cobalt and copper concentrations were significantly higher in patients with tuberculosis compared with controls, while zinc and selenium concentrations were significantly lower (p < 0.01). Moreover, serum selenium and zinc concentrations were positively correlated (ρ = 0.41, p < 0.05). A high serum copper concentration was associated with a worse clinical outcome, as assessed after one month of antituberculosis therapy. Specifically, culture-positive patients had higher serum copper concentrations than culture-negative patients (p < 0.05). Patients with tuberculosis had altered serum trace element concentrations. Further research is needed to elucidate the roles of individual trace elements and to determine their clinical impact on patients with tuberculosis.

Therapeutic Effects of Bupleurum Polysaccharides in Streptozotocin Induced Diabetic Mice

Diabetes mellitus is related to low-grade chronic inflammation and oxidative stress. Bupleurum Polysaccharides (BPs), isolated from Bupleurum smithii var. parvifolium has anti-inflammatory and anti-oxidative properties. However, little is known about its therapeutic effects on diabetes. In this experiment, the effects of BPs on alleviation of diabetes and the underlying mechanisms were investigated. Diabetic mice model was established via successive intraperitoneal injections of streptozotocin (100 mg/kg body weight) for two days. Mice with blood glucose levels higher than 16.8mmol/L were selected for experiments. The diabetic mice were orally administered with BPs (30 and 60 mg/kg) once a day for 35 days. BPs not only significantly decreased levels of blood glucose, but also increased those of serum insulin and liver glycogen in diabetic mice compared to model mice. Additionally, BPs adminstration improved the insulin expression and suppressed the apoptosis in pancreas of the diabetic mice. Histopathological observations further demonstrated that BPs protected the pancreas and liver from oxidative and inflammatory damages. These results suggest that BPs protect pancreatic β cells and liver hepatocytes and ameliorate diabetes, which is associated with its anti-oxidative and anti-inflammatory properties.

Metallothionein immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour

Background

To compare the metallothionein (MT) immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour (KOT), to correlate MT with cellular proliferation, and to evaluate the influence of inflammation in MT.

Material and Methods

Fourteen cases of KOT were submitted to immunohistochemistry for MT and Ki-67 analysis. The lesions were grouped according to their grade of inflammation, and statistical analysis was performed.

Results

MT was higher in non-syndromic KOT than in syndromic KOT (p<0.05). No statistical difference in Ki-67 could be identified; however, an inverse correlation was observed between MT and Ki-67 in both lesions. When analysing inflammation, non-syndromic KOT showed no differences in either MT or Ki-67.

Conclusions

The MT immunophenotype of syndromic KOT was different from non-syndromic KOT. MT might not be involved in the proliferation control of both KOT. MT and Ki-67 immunoexpressions proved to be unaffected by inflammation in non-syndromic KOT.

Key words: Odontogenic tumours, basal cell nevus syndrome, metallothionein, Ki-67 Antigen, immunohistoche-mistry.

Ameliorating role of rutin on oxidative stress induced by iron overload in hepatic tissue of rats

Iron is an essential element that participates in several metabolic activities of cells; however, excess iron is a major cause of iron-induced oxidative stress and several human diseases. Natural flavonoids, as rutin, are well-known antioxidants and could be efficient protective agents. Therefore, the present study was undertaken to evaluate the protective influence of rutin supplementation to improve rat antioxidant systems against IOL-induced hepatic oxidative stress. Sixty male albino rats were randomly divided to three equal groups. The first group, the control, the second group, iron overload group, the third group was used as iron overload+rutin group. Rats received six doses of ferric hydroxide polymaltose (100 mg kg(-1) b.wt.) as one dose every two days, by intraperitoneal injections (IP) and administrated rutin (50 mg kg(-1) b.wt.) as one daily oral dose until the sacrificed day. Blood samples for serum separation and liver tissue specimens were collected three times, after three, four and five weeks from the onset of the experiment. Serum iron profiles total iron, Total Iron Binding Capacity (TIBC), Unsaturated Iron Binding Capacity (UIBC), transferrin (Tf) and Transferrin Saturation% (TS%)}, ferritin, albumin, total Protein, total cholesterol, triacylglycerols levels and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were determined. Moreover, total iron in the liver, L-malondialdehyde (L-MDA), glutathione (GSH), Nitric Oxide (NO) and Total Nucleic Acid (TNA) levels and glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) activities were also determined. The obtained results revealed that, iron overload (IOL) resulted in significant increase in serum iron, TIBC, Tf, TS% and ferritin levels and AST and ALT activities and also increased liver iron, L-MDA and NO levels. Meanwhile, it decreased serum UIBC, total cholesterol, triacylglycerols, albumin, total protein and liver GSH, TNA levels and Gpx, CAT and SOD activities when compared with the control group. Rutin administration to iron-overloaded rats resulted in significant decrease in serum total iron, TIBC, Tf, TS%, ferritin levels and AST and ALT activities and liver total iron, L-MDA and NO levels with significant increases in serum UIBC, albumin, total protein and total cholesterol levels and in liver GSH, CAT and SOD activities compared with the IOL group. This study provides in vivo evidence that rutin administration can improve the antioxidant defense systems against IOL-induced hepatic oxidative stress in rats. This protective effect in liver of iron-loaded rats may be due to both antioxidant and metal chelation activities.

Zip4 mediated zinc influx stimulates insulin secretion in pancreatic beta cells

Zinc has an important role in normal pancreatic beta cell physiology as it regulates gene transcription, insulin crystallization and secretion, and cell survival. Nevertheless, little is known about how zinc is transported through the plasma membrane of beta cells and which of the class of zinc influx transporters (Zip) is involved. Zip4 was previously shown to be expressed in human and mouse beta cells; however, its function there is still unknown. Therefore, the aim of this study was to define the zinc transport role of Zip4 in beta cells. To investigate this, Zip4 was over-expressed in MIN6 beta cells using a pCMV6-Zip4GFP plasmid. Organelle staining combined with confocal microscopy showed that Zip4 exhibits a widespread localization in MIN6 cells. Time-lapse zinc imaging experiments showed that Zip4 increases cytoplasmic zinc levels. This resulted in increased granular zinc content and glucose-stimulated insulin secretion. Interestingly, it is unlikely that the increased glucose stimulated insulin secretion was triggered by a modulation of mitochondrial function, as mitochondrial membrane potential remained unchanged. To define the role of Zip4 in-vivo, we generated a beta cell-specific knockout mouse model (Zip4BKO). Deletion of the Zip4 gene was confirmed in Zip4BKO islets by PCR, RT-PCR, and immuno-histochemistry. Zip4BKO mice showed slightly improved glucose homeostasis but no change in insulin secretion during an oral glucose tolerance test. While Zip4 was not found to be essential for proper glucose homeostasis and insulin secretion in vivo in mice, this study also found that Zip4 mediates increases in cytoplasmic and granular zinc pools and stimulates glucose dependant insulin secretion in-vitro.

Amelioration Effect of Zinc and Iron Supplementation on Selected Oxidative Stress Enzymes in Liver and Kidney of Cadmium-Treated Male Albino Rat

Cadmium (Cd) is a highly toxic, nonessential heavy metal with many industrial uses that can contribute to a well-defined spectrum of diseases in animals as well as in humans. The present study examines the effect of zinc (Zn) and iron (Fe) supplementation on oxidative stress enzymes in Cd-treated rats. Wistar strain male albino rats were treated with cadmium chloride (CdCl2) at a dose of 1/10(th) LD50/48 h, that is, 22.5 mg/kg body weight for 7, 15, and 30 days (d) time intervals. The 15d Cd-treated rats were divided into three groups. The first group received Zn (12 mg/kg), second group Fe (40 mg/kg) alone, and third group supplemented with both Zn and Fe and observed for 7, 15, and 30d. After the specific time intervals, rats were decapitated and oxidative stress enzymes like catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione S-transferase (GST) were assayed in liver and kidney. Simultaneously lipid peroxidation (LPO) levels were also measured. A significant elevation in LPO levels with decreased activity levels of CAT, SOD, GPx, and GST were observed during Cd intoxication. With Zn and/or Fe supplementation, a significant reversal in the oxidative stress enzymes was observed. Our study reveals that combination of Zn and Fe supplementation is effective in detoxifying the Cd body burden from the test tissues.

Lactobacillus casei-01 facilitates the ameliorative effects of proanthocyanidins extracted from lotus seedpod on learning and memory impairment in scopolamine-induced amnesia mice

Learning and memory abilities are associated with alterations in gut function. The two-way proanthocyanidins-microbiota interaction in vivo enhances the physiological activities of proanthocyanidins and promotes the regulation of gut function. Proanthocyanidins extracted from lotus seedpod (LSPC) have shown the memory-enhancing ability. However, there has been no literature about whether Lactobacillus casei-01 (LC) enhances the ameliorative effects of LSPC on learning and memory abilities. In this study, learning and memory abilities of scopolamine-induced amnesia mice were evaluated by Y-maze test after 20-day administration of LC (10⁹ cfu/kg body weight (BW)), LSPC (low dose was 60 mg/kg BW (L-LSPC) and high dose was 90 mg/kg BW (H-LSPC)), or LSPC and LC combinations (L-LSPC+LC and H-LSPC+LC). Alterations in antioxidant defense ability and oxidative damage of brain, serum and colon, and brain cholinergic system were investigated as the possible mechanisms. As a result, the error times of H-LSPC+LC group were reduced by 41.59% and 68.75% relative to those of H-LSPC and LC groups respectively. LSPC and LC combinations ameliorated scopolamine-induced memory impairment by improving total antioxidant capacity (TAOC) level, glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) activities of brain, serum and colon, suppressing malondialdehyde (MDA) level of brain, serum and colon, and inhibiting brain acetylcholinesterase (AchE), myeloperoxidase, total nitric oxide synthase and neural nitric oxide synthase (nNOS) activities, and nNOS mRNA level. Moreover, LC facilitated the ameliorative effects of H-LSPC on GSH-Px activity of colon, TAOC level, GSH-Px activity and ratio of T-SOD to MDA of brain and serum, and the inhibitory effects of H-LSPC on serum MDA level, brain nNOS mRNA level and AchE activity. These results indicated that LC promoted the memory-enhancing effect of LSPC in scopolamine-induced amnesia mice.

Identification and characterization of membrane androgen receptors in the ZIP9 zinc transporter subfamily: II. Role of human ZIP9 in testosterone-induced prostate and breast cancer cell apoptosis

Recently, we discovered a cDNA in teleost ovarian follicle cells belonging to the zinc transporter ZIP9 subfamily (SLC39A9) encoding a protein with characteristics of a membrane androgen receptor (mAR). Here, we demonstrate that human ZIP9 expressed in MDA-MB-468 breast cancer cells and stably overexpressed in human prostate cancer PC-3 cells (PC-3-ZIP9) also displays the ligand binding and signaling characteristics of a specific, high-affinity mAR. Testosterone treatment of MDA-MB-468 and PC-3-ZIP9 cells caused activation of G proteins and second messenger pathways as well as increases in intracellular free zinc concentrations that were accompanied by induction of apoptosis. [1,2,6,7-(3)H]-testosterone binding and these responses were abrogated in MDA-MB-468 cells after ZIP9 small interfering RNA (siRNA) treatment and absent in PC-3 cells transfected with empty vector, confirming that ZIP9 functions as an mAR. Testosterone treatment caused up-regulation of proapoptotic genes Bax (Bcl-2-associated X protein), p53 (tumor protein p53), and JNK (c-Jun N-terminal kinases) in both cell lines and increased expression of Bax, Caspase 3, and cytochrome C proteins. Treatment with a zinc chelator or a MAPK inhibitor blocked testosterone-induced increases in Bax, p53, and JNK mRNA expression. The results suggest that both androgen signaling and zinc transporter functions of ZIP9 mediate testosterone promotion of apoptosis. ZIP9 is widely expressed in human tissues and up-regulated in malignant breast and prostate tissues, suggesting that it is a potential therapeutic target for treating breast and prostate cancers. These results provide the first evidence for a mechanism mediated by a single protein through which steroid and zinc signaling pathways interact to regulate physiological functions in mammalian cells.

Optimized rapeseed oils rich in endogenous micronutrients ameliorate risk factors of atherosclerosis in high fat diet fed rats

BACKGROUND

Micronutrients in rapeseed such as polyphenols, tocopherols, phytosterols and phospholipids in rapeseed exert potential benefit to atherosclerosis. Some part of these healthy components substantially lost during the conventional refining processing. Thus some new processing technologies have been developed to produce various endogenous micronutrient-enriched optimized rapeseed oils. The aim of this study is to assess whether optimized rapeseed oils have positive effects on the atherosclerosis risk factors in rats fed a high-fat diet.

METHODS

Rats received experiment diets containing 20% fat and refined rapeseed oil or optimized rapeseed oils obtained with various processing technologies as lipid source. After 10 weeks of treatment, plasma was assayed for oxidative stress, lipid profiles and imflammation.

RESULTS

Micronutrients enhancement in optimized rapeseed oils significantly reduced plasma oxidative stress, as evaluated by the significant elevation in the activities of CAT and GPx as well as the level of GSH, and the significant decline in lipid peroxidation. Optimized rapeseed oil with the highest micronutrient contents obtained by microwave pretreatment-cold pressing reduced the levels of TG, TC and LDL-C as well as IL-6 and CRP in plasma.

CONCLUSIONS

These results suggest that optimized rapeseed oils may contribute to prevent atherogenesis and make them very promising functional food in cardiovascular health promotion.

Sputum containing zinc enhances carbapenem resistance, biofilm formation and virulence of Pseudomonas aeruginosa

Pseudomonas aeruginosa chronic lung infections are the leading cause of mortality in cystic fibrosis patients, a serious problem which is notably due to the numerous P. aeruginosa virulence factors, to its ability to form biofilms and to resist the effects of most antibiotics. Production of virulence factors and biofilm formation by P. aeruginosa is highly coordinated through complex regulatory systems. We recently found that CzcRS, the zinc and cadmium-specific two-component system is not only involved in metal resistance, but also in virulence and carbapenem antibiotic resistance in P. aeruginosa. Interestingly, zinc has been shown to be enriched in the lung secretions of cystic fibrosis patients. In this study, we investigated whether zinc might favor P. aeruginosa pathogenicity using an artificial sputum medium to mimic the cystic fibrosis lung environment. Our results show that zinc supplementation triggers a dual P. aeruginosa response: (i) it exacerbates pathogenicity by a CzcRS two-component system-dependent mechanism and (ii) it stimulates biofilm formation by a CzcRS-independent mechanism. Furthermore, P. aeruginosa cells embedded in these biofilms exhibited increased resistance to carbapenems. We identified a novel Zn-sensitive regulatory circuit controlling the expression of the OprD porin and modifying the carbapenem resistance profile. Altogether our data demonstrated that zinc levels in the sputum of cystic fibrosis patients might aggravate P. aeruginosa infection. Targeting zinc levels in sputum would be a valuable strategy to curb the increasing burden of P. aeruginosa infections in cystic fibrosis patients.

Zinc supplementation protects against cadmium accumulation and cytotoxicity in Madin-Darby bovine kidney cells

Cadmium ions (Cd2+) have been reported to accumulate in bovine tissues, although Cd2+ cytotoxicity has not been investigated thoroughly in this species. Zinc ions (Zn2+) have been shown to antagonize the toxic effects of heavy metals such as Cd2+ in some systems. The present study investigated Cd2+ cytotoxicity in Madin-Darby bovine kidney (MDBK) epithelial cells, and explored whether this was modified by Zn2+. Exposure to Cd2+ led to a dose- and time-dependent increase in apoptotic cell death, with increased intracellular levels of reactive oxygen species and mitochondrial damage. Zn2+ supplementation alleviated Cd2+-induced cytotoxicity and this protective effect was more obvious when cells were exposed to a lower concentration of Cd2+ (10 μM), as compared to 50 μM Cd2+. This indicated that high levels of Cd2+ accumulation might induce irreversible damage in bovine kidney cells. Metallothioneins (MTs) are metal-binding proteins that play an essential role in heavy metal ion detoxification. We found that co-exposure to Zn2+ and Cd2+ synergistically enhanced RNA and protein expression of MT-1, MT-2, and the metal-regulatory transcription factor 1 in MDBK cells. Notably, addition of Zn2+ reduced the amounts of cytosolic Cd2+ detected following MDBK exposure to 10 μM Cd2+. These findings revealed a protective role of Zn2+ in counteracting Cd2+ uptake and toxicity in MDBK cells, indicating that this approach may provide a means to protect livestock from excessive Cd2+ accumulation.

A combination of flaxseed oil and astaxanthin alleviates atherosclerosis risk factors in high fat diet fed rats

Background

Atherosclerosis is the most common pathologic process underlying cardiovascular disease. Both flaxseed oil (FO) and astaxanthin (ASX) are believed to benefit cardiovascular system. The combined effect of FO and ASX on the atherosclerosis risk factors in rats fed a high-fat diet was investigated.

Methods

Astaxanthin was dissolved in flaxseed oil to a final concentration of 1g/kg (FO + ASX). Male Sprague–Dawley rats were fed a rodent diet contained 20% fat whose source was lard (HFD) or 75% lard and 25% FO + ASX (50 mg ASX/kg diet) or 50% lard and 50% FO + ASX (100 mg ASX/kg diet) or FO + ASX (200 mg ASX/kg diet) for 10 weeks.

Results

The combination of FO and ASX significantly increased the antioxidant defense capacity and decreased lipid peroxidation in plasma. Evident decreases in the levels TG, TC and LDL-C contents, as well as IL-6 and CRP were also observed in plasma of FO and ASX fed rats.

Conclusion

The combination of FO and ASX can improve oxidative stress, lipid abnormalities and inflammation, providing evidence that the combination of FO and ASX could be a promising functional food in cardiovascular health promotion.

Zinc causes acute impairment of glutathione metabolism followed by coordinated antioxidant defenses amplification in gills of brown mussels Perna perna

Zinc demonstrates protective and antioxidant properties at physiological levels, although these characteristics are not attributed at moderate or high concentrations. Zinc toxicity has been related to a number of factors, including interference with antioxidant defenses. In particular, the inhibition of glutathione reductase (GR) has been suggested as a possible mechanism for acute zinc toxicity in bivalves. The present work investigates the biochemical effects of a non-lethal zinc concentration on antioxidant-related parameters in gills of brown mussels Perna perna exposed for 21 days to 2.6 μM zinc chloride. After 2 days of exposure, zinc caused impairment of the antioxidant system, decreasing GR activity and glutathione levels. An increase in antioxidant defenses became evident at 7 and 21 days of exposure, as an increase in superoxide dismutase and glutathione peroxidase activity along with restoration of glutathione levels and GR activity. After 7 and 21 days, an increase in cellular peroxides and lipid peroxidation end products were also detected, which are indicative of oxidative damage. Changes in GR activity contrasts with protein immunoblotting data, suggesting that zinc produces a long lasting inhibition of GR. Contrary to the general trend in antioxidants, levels of peroxiredoxin 6 decreased after 21 days of exposure. The data presented here support the hypothesis that zinc can impair thiol homeostasis, causes an increase in lipid peroxidation and inhibits GR, imposing a pro-oxidant status, which seems to trigger homeostatic mechanisms leading to a subsequent increase on antioxidant-related defenses.

Copper and resveratrol attenuates serum catalase, glutathione peroxidase, and element values in rats with DMBA-induced mammary carcinogenesis

In this paper, a hypothesis was assessed whether or not the intoxication with copper and supplementation with copper plus resveratrol would result in changes in the activities of catalase and glutathione peroxidase and moreover if the characteristic changes would appear in concentrations of copper, iron, calcium, magnesium, and zinc in the serum of rats with chemically induced carcinogenesis. Female Sprague-Dawley rats were divided into study groups which, apart from the standard diet, were treated with copper (42.6 mg Cu/kg food as CuSO4·5H2O) or copper plus resveratrol (0.2 mg/kg body) via gavage for a period from 40 days until 20 weeks of age. In cancer groups, the rats were treated with a dose of 80 mg/body weight of 7,12-dimethyl-1,2-benz[a]anthracene (DMBA) given in rapeseed oil at 50 and 80 days of age to induce mammary carcinogenesis. The control groups included the rats kept in the same conditions and fed with the same diet as the animals from the study groups, but not DMBA-treated. The activity of catalase significantly decreased in groups of rats with mammary carcinogenesis that were supplemented with copper (p < 0.05) or copper plus resveratrol (p < 0.001) in comparison with the control groups that received the same diets. In cancer groups of nonsupplemented rats, the increase of glutathione peroxidase activity was observed. The process of carcinogenesis and the applied supplementation significantly altered the concentrations of trace elements in serum, in particular as concerns iron and copper. The mean serum iron levels in rats with breast cancer were significantly lower than those in the control groups (p < 0.001). The mean serum copper levels significantly decreased in the groups of rats with mammary carcinogenesis that were supplemented with copper or copper plus resveratrol in comparison with the control groups that received the same diets (p < 0.001). The characteristic changes in iron content and the zinc/copper and zinc/iron ratios in blood may be used as one of the prognostic factors in breast cancer research.

Antidiabetic activity of mycelia selenium-polysaccharide from Catathelasma ventricosum in STZ-induced diabetic mice

Se-polysaccharide from Catathelasma ventricosum (SPC-2) was purified by DEAE-52 and Sephadex G-100 column chromatography. The average size of SPC-2 was 1.6×10(5) Da, and it was mainly composed of glucose (87.4%) with the conformation of β-pyran ring. The branched structure of SPC-2 was proved intuitively by atomic force microscope (AFM). The antidiabetic potential of SPC-2 was tested in STZ-induced diabetic mice. After STZ-induced diabetic mice being administered of SPC-2 for 30 days, SPC-2 treatment significantly reduced the levels of malondialdehyde (MDA) and low-density lipoprotein cholesterol (LDL-C) that were increased by the STZ treatment. Further, the SPC-2 treatment led to increased activity of antioxidant enzymes in liver and kidney and high-density lipoprotein cholesterol (HDL-C) that were decreased by the STZ. The results of histopathology also showed SPC-2 protected tissues (pancreas, liver and kidney) against peroxidation damage and maintained tissue integrity.

Serum metallothioneins in childhood tumours-a potential prognostic marker

Metallothioneins (MT) are low molecular weight, cysteine-rich proteins maintaining metal ions homeostasis. They play a role in carcinogenesis and may also cause chemoresistance. The aim of the study was to explore the importance of MT serum levels in children suffering from malignant tumours. This prospective study involves examination of 865 samples from 172 patients with malignant tumours treated from 2008 to 2011 at University Hospital Motol. MT serum levels were determined using differential pulse voltammetry-Brdicka reaction. Mean MT level was 2.7 ± 0.5 μM. There was no statistically significant difference between MT levels in different tumours. We also did not find any correlation between MT levels and response to therapy or clinical stages. However, we found a positive correlation between MT levels and age (p = 0.009) and a negative correlation with absolute lymphocyte number (p = 0.001). The fact that patients who had early disease recurrence had lower MT levels during the treatment (complete remission 2.67 vs. recurring 2.34, p = 0.001) seems to be important for clinical practice. Accordingly we believe that there is benefit in further studies of serum MT levels in tumours.

Protein antioxidants in thalassemia

It is common knowledge that thalassemic patients are under significant oxidative stress. Chronic hemolysis, frequent blood transfusion, and increased intestinal absorption of iron are the main factors that result in iron overload with its subsequent pathophysiologic complications. Iron overload frequently associates with the generation of redox-reactive labile iron, which in turn promotes the production of other reactive oxygen species (ROS). If not neutralized, uncontrolled production of ROS often leads to damage of various intra- and extracellular components such as DNA, proteins, lipids, and small antioxidant molecules among others. A number of endogenous and exogenous defense mechanisms can neutralize and counteract the damaging effects of labile iron and the reactive substances associated with it. Endogenous antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and ferroxidase, may directly or sequentially terminate the activities of ROS. Nonenzymatic endogenous defense mechanisms include metal binding proteins (ceruloplasmin, haptoglobin, albumin, and others) and endogenously produced free radical scavengers (glutathione (GSH), ubiquinols, and uric acid). Exogenous agents that are known to function as antioxidants (vitamins C and E, selenium, and zinc) are mostly diet-derived. In this review, we explore recent findings related to various antioxidative mechanisms operative in thalassemic patients with special emphasis on protein antioxidants.

Flaxseed oil and α-lipoic acid combination reduces atherosclerosis risk factors in rats fed a high-fat diet

BACKGROUND

Atherosclerosis is a major manifestation of the pathophysiology underlying cardiovascular disease. Flaxseed oil (FO) and α-lipoic acid (LA) have been reported to exert potential benefit to cardiovascular system. This study tried to assess the effect of supplement of FO and LA combination on the atherosclerosis risk factors in rats fed a high-fat diet.

METHODS

LA was dissolved in flaxseed oil to a final concentration of 8 g/kg (FO+LA) when used. The rodent diet contained 20% fat. One-fifth of the fat was soybean oil and the others were lard (HFD group), or 75% lard and 25% FO+LA (L-FO+LA group), or 50% lard and 50% FO+LA (M-FO+LA group), or FO+LA (H-FO+LA group). Animals were fed for 10 weeks and then killed for blood collection.

RESULTS

Supplement of FO and LA combination significantly enhanced plasma antioxidant defense capacities, as evaluated by the marked increase in the activities of SOD, CAT and GPx as well as the level of GSH, and the significant reduction in lipid peroxidation. Simultaneous intake of FO and LA also reduced plasma TG, TC and LDL-C contents and elevated the ratio of HDL-C/LDL-C. Besides, in parallel with the increase of FO and LA combination, plasma IL-6 and CRP levels were remarkably reduced.

CONCLUSION

Supplement of FO and LA combination may contribute to prevent atherogenesis by improving plasma oxidative stress, lipid profile and inflammation.

Protective antioxidant and antiapoptotic effects of ZnCl2 in rat pancreatic islets cultured in low and high glucose concentrations

Aim/Hypothesis

Rat pancreatic islet cell apoptosis is minimal after prolonged culture in 10 mmol/l glucose (G10), largely increased in 5 mmol/l glucose (G5) and moderately increased in 30 mmol/l glucose (G30). This glucose-dependent asymmetric V-shaped profile is preceded by parallel changes in the mRNA levels of oxidative stress-response genes like Metallothionein 1a (Mt1a). In this study, we tested the effect of ZnCl₂, a potent inducer of Mt1a, on apoptosis, mitochondrial oxidative stress and alterations of glucose-induced insulin secretion (GSIS) induced by prolonged exposure to low and high vs. intermediate glucose concentrations.

Methods

Male Wistar rat islets were cultured in RPMI medium. Islet gene mRNA levels were measured by RTq-PCR. Apoptosis was quantified by measuring islet cytosolic histone-associated DNA fragments and the percentage of TUNEL-positive β-cells. Mitochondrial thiol oxidation was measured in rat islet cell clusters expressing “redox sensitive GFP” targeted to the mitochondria (mt-roGFP1). Insulin secretion was measured by RIA.

Results

As observed for Mt1a mRNA levels, β-cell apoptosis and loss of GSIS, culture in either G5 or G30 vs. G10 significantly increased mt-roGFP1 oxidation. While TPEN decreased Mt1a/2a mRNA induction by G5, addition of 50–100 µM ZnCl₂ to the culture medium strongly increased Mt1a/2a mRNA and protein levels, reduced early mt-roGFP oxidation and significantly decreased late β-cell apoptosis after prolonged culture in G5 or G30 vs. G10. It did not, however, prevent the loss of GSIS under these culture conditions.

Conclusion

ZnCl₂ reduces mitochondrial oxidative stress and improves rat β-cell survival during culture in the presence of low and high vs. intermediate glucose concentrations without improving their acute GSIS.

Effects of chronic cadmium poisoning on Zn, Cu, Fe, Ca, and metallothionein in liver and kidney of rats

An experiment was conducted to invest effects of chronic cadmium poisoning on Zn, Cu, Fe, Ca, and metallothionein gene expression and protein synthesis in liver and kidney in rats. Forty rats, 6 weeks old, were randomly allocated into two groups. A group was given CdCl(2) (1 mg/KgCd(2+)) by intraperitoneal injection once a day. The other group was treated with normal saline in the same way. Liver and kidney were collected for analysis at the end of the third week. Results showed that Cd exposure increased Cd (P<0.01) and Zn (P<0.01) content both in liver and kidney. Fe and Ca concentration had a considerable increase in kidney (P<0.01), while both had different degree reduction in liver. Discrepancies between MT mRNA and protein were observed in liver and kidney. In liver, both MT mRNA and protein had a significant increase (P<0.01), while in kidney, only MT gene increase was checked. Meanwhile, the expression levels of MT-1 mRNA and MT-2 mRNA were distinct between liver and kidney. The present study indicated that changes in tissue Cd and Zn levels tended to reflect MT mRNA expression, but bear no clear relationship with MT protein. There did not have a strict dose-dependent relationship among Cd content, MT gene expression, and MT protein synthesis. What is more, changes of Zn, Fe, Cu, and Ca had a certain interaction with both MT mRNA and protein.

Protective effect of pravastatin against mercury induced vascular cells damage: erythrocytes as surrogate markers

In the present study we investigated the protective effect of pravastatin (PRV) against mercury-induced cellular damage. Human erythrocytes were incubated with PRV, HgCl(2) and HgCl(2) pretreated with PRV. Our results revealed that incubation of erythrocytes with HgCl(2) induces a significant increase the ratios of superoxide dismutase/glutathione peroxidase (SOD/GPx), superoxide dismutase/catalase (SOD/CAT), oxidized/reduced glutathione (GSSG/GSH), malondialdehyde(MDA) and protein carbonyl(PCO) by 60%, 50%, 333%, 400% and 208% respectively. Whereas, prior incubation of erythrocytes with PRV maintains these parameters at values similar to control cells. Furthermore, the level of nitrite in erythrocytes decreases significantly on treatment with HgCl(2), whereas it remains similar to the control when pretreated with PRV. Also, there was an increase in erythrocytes hemolysis when treated with HgCl(2), whereas it remained the like to the control when pretreated with PRV. In conclusion, PRV pretreatment maintained the erythrocytes oxidant/antioxidant balance and nitrite level during mercury exposure. Consequently, PRV pretreatment is worthy of further investigation in the reduction of the cardiovascular risk of mercury.

Global gene expression profiling of human lung epithelial cells after exposure to nanosilver

The toxic effects of silver nanoparticles (AgNPs) on cells are well established, but only limited studies on the effect of AgNPs and silver ions on the cellular transcriptome have been performed. In this study, the effect of AgNPs on the gene expression in the human lung epithelial cell line A549 exposed to 12.1 µg/ml AgNPs (EC20) for 24 and 48h was compared with the response to control and silver ion (Ag(+)) treated cells (1.3 µg/ml) using microarray analysis. Twenty-four hours to AgNP altered the regulation of more than 1000 genes (more than twofold regulation), whereas considerably fewer genes responded to Ag(+) (133 genes). The upregulated genes included members of the metallothionein, heat shock protein, and histone families. As expected from the induction of meta l lothionein and heat shock protein genes, Ag(+) and AgNP treatment resulted in intracellular production of reactive oxygen species but did not induce apoptosis or necrosis at the concentrations used in this study. In addition, the exposure to AgNPs influenced the cell cycle and led to an arrest in the G2/M phase as shown by cell cycle studies by flow cytometry and microscopy. In conclusion, although the transcriptional response to Ag(+) exposure was highly related to the response caused by AgNPs, our findings suggest that AgNPs, due to their particulate form, affect exposed cells in a more complex way.

Patient-derived fibroblasts indicate oxidative stress status and may justify antioxidant therapy in OXPHOS disorders

Oxidative phosphorylation disorders are often associated with increased oxidative stress and antioxidant therapy is frequently given as treatment. However, the role of oxidative stress in oxidative phosphorylation disorders or patients is far from clear and consequently the preventive or therapeutic effect of antioxidants is highly anecdotic. Therefore, we performed a systematic study of a panel of oxidative stress parameters (reactive oxygen species levels, damage and defense) in fibroblasts of twelve well-characterized oxidative phosphorylation patients with a defect in the POLG1 gene, in the mitochondrial DNA-encoded tRNA-Leu gene (m.3243A>G or m.3302A>G) and in one of the mitochondrial DNA-encoded NADH dehydrogenase complex I (CI) subunits. All except two cell lines (one POLG1 and one tRNA-Leu) showed increased reactive oxygen species levels compared with controls, but only four (two CI and two tRNA-Leu) cell lines provided evidence for increased oxidative protein damage. The absence of a correlation between reactive oxygen species levels and oxidative protein damage implies differences in damage prevention or correction. This was investigated by gene expression studies, which showed adaptive and compensating changes involving antioxidants and the unfolded protein response, especially in the POLG1 group. This study indicated that patients display individual responses and that detailed analysis of fibroblasts enables the identification of patients that potentially benefit from antioxidant therapy. Furthermore, the fibroblast model can also be used to search for and test novel, more specific antioxidants or explore ways to stimulate compensatory mechanisms.

Effects of high-fat diet feeding on Znt8-null mice: differences between β-cell and global knockout of Znt8

Genomewide association studies have linked a polymorphism in the zinc transporter 8 (Znt8) gene to higher risk of developing type 2 diabetes. Znt8 is highly expressed in pancreatic β-cells where it is involved in the regulation of zinc transport into granules. However, Znt8 is also expressed in other tissues including α-cells, where its function is as yet unknown. Previous work demonstrated that mice lacking Znt8 globally were more susceptible to diet-induced obesity (Lemaire et al., Proc Natl Acad Sci USA 106: 14872-14877, 2009; Nicolson et al., Diabetes 58: 2070-2083, 2009). Therefore, the main goal of this study was to examine the physiological impact of β-cell-specific Znt8 deficiency in mice during high-fat high-calorie (HFHC) diet feeding. For these studies, we used β-cell-specific Znt8 knockout (Ins2Cre:Znt8loxP/loxP) and whole body Znt8 knockout (Cre-:Znt8(-/-)) mice placed on a HFHC diet for 16 wk. Ins2Cre:Znt8loxP/loxP mice on HFHC diet had similar body weights throughout the study but displayed impaired insulin biosynthesis and secretion and were glucose intolerant compared with littermate control Ins2Cre mice. In contrast, Cre-:Znt8(-/-) mice became remarkably obese, hyperglycemic, hyperinsulinemic, insulin resistant, and glucose intolerant compared with littermate control Cre- mice. These data show that β-cell Znt8 alone does not considerably aggravate weight gain and glucose intolerance during metabolic stress imposed by an HFHC diet. However, global loss of Znt8 is involved in exacerbating diet-induced obesity and resulting insulin resistance, and this may be due to the loss of Znt8 activity in a tissue other than the β-cell. Thus, our data suggest that Znt8 contributes to the risk of developing type 2 diabetes through β-cell- and non-β-cell-specific effects.

Protein carbonyl, 3β-, and 17β-hydroxysteroid dehydrogenases in testes and serum FSH, LH, and testosterone levels in zinc deficient Wistar rats

The present study evaluated protein oxidation, alteration in hydroxysteroid dehydrogenases (3β- and 17β HSD) in testes and serum hormonal profiles of dietary zinc deficient Wistar rats. Pre-pubertal rats were divided into three groups: zinc control (ZC), pairfed (PF), and zinc deficient (ZD) and fed 100 ppm (ZC and PF groups) and 1.0 ppm (ZD group) zinc diet for 2- and 4-weeks. The testes from zinc deficient groups exhibited significant increase in total protein (2 weeks) and protein carbonyl (2- and 4-weeks) concentration as well as 3β- and 17β-hydroxysteroid dehydrogenase activities (4 weeks), whereas a significant decrease was recorded in total protein (testes 4 weeks; serum 2- and 4-weeks), total zinc (testes and serum 2- and 4-weeks), 3β- and 17β-hydroxysteroid dehydrogenase activities (testes 2 weeks), and serum hormonal profiles (FSH and testosterone 2- and 4-weeks). However, LH was below the detectable limits. These results reflect that zinc deficiency during pre-pubertal period affected total protein and zinc status, elevates protein oxidation, and causes dysregulation of the hydroxysteroid dehydrogenases. Low level of zinc attenuated the gonadal physiology which indicates that the metabolic regulation of testes is mediated by combined effects of a specific response (caused by decreased zinc concentration) and a nonspecific response (inhibition of gonadotrophin secretion). All these contribute to testicular dysfunction.

Protein kinase CK2 triggers cytosolic zinc signaling pathways by phosphorylation of zinc channel ZIP7

The transition element zinc, which has recently been identified as an intracellular second messenger, has been implicated in various signaling pathways, including those leading to cell proliferation. Zinc channels of the ZIP (ZRT1- and IRT1-like protein) family [also known as solute carrier family 39A (SLC39A)] transiently increase the cytosolic free zinc (Zn(2+)) concentration in response to extracellular signals. We show that phosphorylation of evolutionarily conserved residues in endoplasmic reticulum zinc channel ZIP7 is associated with the gated release of Zn(2+) from intracellular stores, leading to activation of tyrosine kinases and the phosphorylation of AKT and extracellular signal-regulated kinases 1 and 2. Through pharmacological manipulation, proximity ligation assay, and mutagenesis, we identified protein kinase CK2 as the kinase responsible for ZIP7 activation. Together, the present results show that transition element channels in eukaryotes can be activated posttranslationally by phosphorylation, as part of a cell signaling cascade. Our study links the regulated release of zinc from intracellular stores to phosphorylation of kinases involved in proliferative responses and cell migration, suggesting a functional role for ZIP7 and zinc signals in these events. The connection with proliferation and migration, as well as the activation of ZIP7 by CK2, a kinase that is antiapoptotic and promotes cell division, suggests that ZIP7 may provide a target for anticancer drug development.

Putative role of intracellular Zn(2+) release during oxidative stress: a trigger to restore cellular thiol content that is decreased by oxidative stress

Although the ability of zinc to retard the oxidative process has been recognized for many years, zinc itself has been reported to induce oxidative stress. In order to give some insights into elucidating the role of intracellular Zn(2+) in cells suffering from oxidative stress, the effects of N-ethylmaleimide (NEM) and ZnCl(2) on cellular thiol content and intracellular Zn(2+) concentration were studied by use of 5-chloromethylfluorescein diacetate (5-CMF-DA) and FluoZin-3 pentaacetoxymethyl ester (FluoZin-3-AM) in rat thymocytes. The treatment of cells with NEM attenuated 5-CMF fluorescence and augmented FluoZin-3 fluorescence in a dose-dependent manner. These NEM-induced phenomena were observed under external Zn(2+)-free conditions. Results suggest that NEM decreases cellular thiol content and induces intracellular Zn(2+) release. Micromolar ZnCl(2) dose-dependently augmented both FluoZin-3 and 5-CMF fluorescences, suggesting that the elevation of intracellular Zn(2+) concentration increases cellular thiol content. Taken together, it is hypothesized that intracellular Zn(2+) release during oxidative stress is a trigger to restore cellular thiol content that is decreased by oxidative stress.

Mechanism(s) of Toxic Action of Zn and Selenite: A Study on AS-30D Hepatoma Cells and Isolated Mitochondria

Mitochondria of AS-30D rat ascites hepatoma cells are found to be the main target for Zn²⁺ and sodium selenite (Na₂SeO₃). High [mu]M concentrations of Zn²⁺ or selenite were strongly cytotoxic, killing the AS-30D cells by both apoptotic and necrotic ways. Both Zn²⁺ and selenite produced strong changes in intracellular generation of reactive oxygen species (ROS) and the mitochondrial dysfunction via the mitochondrial electron transport chain (mtETC) disturbance, the membrane potential dissipation, and the mitochondrial permeability transition pore opening. The significant distinctions in toxic action of Zn²⁺ and selenite on AS-30D cells were found. Selenite induced a much higher intracellular ROS level (the early event) compared to Zn²⁺ but a lower membrane potential loss and a lower decrease of the uncoupled respiration rate of the cells, whereas the mtETC disturbance was the early and critical event in the mechanism of Zn²⁺ cytotoxicity. Sequences of events manifested in the mitochondrial dysfunction produced by the metal/metalloid under test are compared with those obtained earlier for Cd²⁺, Hg²⁺, and Cu²⁺ on the same model system.

Altered expression of genes involved in inflammation and apoptosis in frontal cortex in major depression

The etiology of major depression (MDD), a common and complex disorder, remains obscure. Gene expression profiling was conducted on post-mortem brain tissue samples from Brodmann Area 10 (BA10) in the prefrontal cortex from psychotropic drug-free persons with a history of MDD and age, gender, and post-mortem interval-matched normal controls (n=14 pairs of subjects). Microarray analysis was conducted using the Affymetrix Exon 1.0 ST arrays. A set of differential expression changes was determined by dual-fold change-probability criteria (∣average log ratios∣>0.585 [equivalent to a 1.5-fold difference in either direction], P<0.01), whereas molecular pathways of interest were evaluated using Gene Set Enrichment Analysis software. The results strongly implicate increased apoptotic stress in the samples from the MDD group. Three anti-apoptotic factors, Y-box-binding protein 1, caspase-1 dominant-negative inhibitor pseudo-ICE, and the putative apoptosis inhibitor FKGS2, were over-expressed. Gene set analysis suggested up-regulation of a variety of pro- and anti-inflammatory cytokines, including interleukin 1α (IL-1α), IL-2, IL-3, IL-5, IL-8, IL-9, IL-10, IL-12A, IL-13, IL-15, IL-18, interferon gamma (IFNγ), and lymphotoxin α (TNF superfamily member 1). The genes showing reduced expression included metallothionein 1M (MT1M), a zinc-binding protein with a significant function in the modulation of oxidative stress. The results of this study indicate that post-mortem brain tissue samples from BA10, a region that is involved in reward-related behavior, show evidence of local inflammatory, apoptotic, and oxidative stress in MDD.

Rapeseed oil fortified with micronutrients reduces atherosclerosis risk factors in rats fed a high-fat diet

Background

Micronutrients polyphenols, tocopherols and phytosterols in rapeseed exert potential benefit to cardiovascular system, but most of these micronutrients are removed by the refining process. The aim of this study was to determine the effect of rapeseed oil fortified with these micronutrients on the atherosclerosis risk factors in rats fed a high-fat diet.

Methods

The rodent diet contained 20% fat whose source was refined rapeseed oil (RRO) or fortified refined rapeseed oil with low, middle and high quantities of these micronutrients (L-, M- and H-FRRO). Forty male SD rats were divided into four groups. One group received RRO diet and other groups received L-, M- and H-FRRO diet for 10 weeks.

Results

Micronutrients supplementation significantly increased plasma antioxidant defense capacities, as evaluated by the significant elevation in the activities of GPx, CAT and SOD as well as the level of GSH, and the significant decline in lipid peroxidation. These micronutrients also reduced the plasma contents of TG, TC and LDL-C and increased the ratio of HDL-C/LDL-C. In addition, in parallel with the enhancement of these micronutrients, plasma levels of IL-6 and CRP declined remarkably.

Conclusion

Rapeseed oil fortified with micronutrients polyphenols, tocopherols and phytosterols may contribute to prevent atherogenesis by ameliorating plasma oxidative stress, lipid profile and inflammation.

MetalDetector v2.0: predicting the geometry of metal binding sites from protein sequence

MetalDetector identifies CYS and HIS involved in transition metal protein binding sites, starting from sequence alone. A major new feature of release 2.0 is the ability to predict which residues are jointly involved in the coordination of the same metal ion. The server is available at http://metaldetector.dsi.unifi.it/v2.0/.

Are apparent negative effects of feeding GM MON810 maize to Atlantic salmon, Salmo salar, caused by confounding factors?

The present study was conducted to follow up on apparent differences in growth, relative organ sizes, cellular stress and immune function in Atlantic salmon fed feed containing GM Bacillus thuringiensis maize compared with feed containing the non-modified parental maize line. Gene expression profiling on the distal intestinal segment and liver was performed by microarray, and selected genes were followed up by quantitative PCR (qPCR). In the liver, qPCR revealed some differentially regulated genes, including up-regulation of gelsolin precursor, down-regulation of ferritin heavy subunit and a tendency towards down-regulation of metallothionein (MT)-B. This, combined with the up-regulation of anti-apoptotic protein NR13 and similar tendencies for ferritin heavy chain and MT-A and -B in the distal intestine, suggests changes in cellular stress/antioxidant status. This corresponds well with and strengthens previous findings in these fish. To exclude possible confounding factors, the maize ingredients were analysed for mycotoxins and metabolites. The GM maize contained 90 μg/kg of deoxynivalenol (DON), while the non-GM maize was below the detection limit. Differences were also observed in the metabolite profiles of the two maize varieties, some of which seemed connected to the mycotoxin level. The effects on salmon observed in the present and previous studies correspond relatively well with the effects of DON as reported in the literature for other production animals, but knowledge regarding effects and harmful dose levels in fish is scarce. Thus, it is difficult to conclude whether the observed effects are caused by the DON level or by some other aspect of the GM maize ingredient.

Effect of dietary supplementation on the prognostic value of urinary and serum 8-isoprostaglandin F2α in chemically-induced mammary carcinogenesis in the rat

Backround

The aim of the present study was to assess the effects of zinc or copper and polyphenolic compounds on the 8-isoprostaglandin F_2α concentration in the serum and urine of rats with mammary cancer (adenocarcinoma) induced with 7,12-dimethylbenz[a]antracene. The research focused on the kinetics of alterations in urinary 8-isoPGF_2α at the early stage of carcinogenesis as well as the influence of dietary factors on the process. The impact of selected compounds on the intensity of DMBA - induced carcinogenesis was also assessed.

Result and conclusions

Administration of DMBA, a compound that inducers mammary tumors in experimental animals, increased the serum and urinary 8-isoPGF_2α levels in study rats. In the rat model, diet supplementation with zinc, combined with selected polyphenolic compounds (resveratrol or genistein) yielded a statistically significant decrease in the rat serum and urinary biomarker concentration with a simultaneously significant stimulation of carcinogenesis.

The results indicate that there is an inverse correlation between the intensity of DMBA-induced carcinogenicity and the level of 8-isoPGF_2α in urine and serum of rats.

Zinc restriction during different periods of life: influence in renal and cardiovascular diseases

Micronutrient undernutrition during critical periods of growth has become an important health issue in developing and developed countries, particularly among pregnant women and children having an imbalanced diet. Zinc is a widely studied microelement in infant feeding because it is a component of several enzymes involved in intermediary metabolism ranging from growth to cell differentiation and metabolism of proteins, carbohydrates, and lipids. Human and experimental studies have reported an association between zinc deficiency and the etiopathogenesis of cardiovascular and renal diseases like hypertension, atherosclerosis, congestive heart failure, coronary heart disease, and diabetes. The main links between the development of these pathologies and zinc deficiency are multiple mechanisms involving oxidative stress damage, apoptosis, and inflammation. A substantial body of evidence suggests that a poor in utero environment elicited by maternal dietary or placental insufficiency may "programme" susceptibility in the fetus to later development of cardiovascular, renal, metabolic, and endocrine diseases. Zinc deficiency in rats during intrauterine and postnatal growth can also be considered a model of fetal programming of cardiovascular and renal diseases in adult life. Dietary zinc restriction during fetal life, lactation, and/or postweaning induces an increase in arterial blood pressure and impairs renal function in adult life. This review focuses on the contributions of experimental and clinical studies to current knowledge of the physiologic role of zinc in the cardiovascular and renal systems. Moreover, this review examines the relationship between zinc deficiency during different periods of life and the development of cardiovascular and renal diseases in adult life.