Iron homeostasis, oxidative stress, and DNA damage

Nitrogen-doped carbon dots for sensitive detection of ferric ions and monohydrogen phosphate by the naked eye and imaging in living cells

Nitrogen doped carbon dots (N-CDs) have been prepared via a one-pot hydrothermal method by using formamide and o-phenylenediamine as the carbon precursors. The as-fabricated N-CDs display excellent water dispersibility, good biocompatibility and anti-photobleaching properties. A strong emission band with an emission maximum (λ ^fl _max) of 556 nm is observed under 450 nm excitation, and a large Stokes shift of 106 nm is presented. However, the fluorescence is quenched by the addition of Fe³⁺; a good linearity is shown in the range of 0-65 μM with a detection limit as low as 0.85 μM. Fortunately, the quenched fluorescence could be recovered rapidly by the addition of monohydrogen phosphate (HPO₄ ^2-) due to the formation of the stable [N-CDs-Fe³⁺-HPO₄ ^2-] complex, and a good linearity is exhibited in the range of 0-60 μM with a low detection limit of 0.80 μM for HPO₄ ^2-. A novel "on-off-on" fluorescence response is seen with an obvious color change from yellow-crimson-yellow by the naked eye. In addition, the confocal microscopy images suggest that the as-synthesized N-CDs could serve as a sensitive nanosensor for Fe³⁺ and HPO₄ ^2- detection, implying the diverse potential application of N-CDs in the biomedical field.

Ferric Uptake Regulator Fur Coordinates Siderophore Production and Defense against Iron Toxicity and Oxidative Stress and Contributes to Virulence in Chromobacterium violaceum

Iron is a highly reactive metal that participates in several processes in prokaryotic and eukaryotic cells. Hosts and pathogens compete for iron in the context of infection. Chromobacterium violaceum, an environmental Gram-negative bacterial pathogen, relies on siderophores to overcome iron limitation in the host. In this work, we studied the role of the ferric uptake regulator Fur in the physiology and virulence of C. violaceum A Δfur mutant strain showed decreased growth and fitness under regular in vitro growth conditions and presented high sensitivity to iron and oxidative stresses. Furthermore, the absence of fur caused derepression of siderophore production and reduction in swimming motility and biofilm formation. Consistent with these results, the C. violaceum Δfur mutant was highly attenuated for virulence and liver colonization in mice. In contrast, a manganese-selected spontaneous fur mutant showed only siderophore overproduction and sensitivity to oxidative stress, indicating that Fur remained partially functional in this strain. We found that mutations in genes related to siderophore biosynthesis and a putative CRISPR-Cas locus rescued the Δfur mutant growth defects, indicating that multiple Fur-regulated processes contribute to maintaining bacterial cell fitness. Overall, our data indicated that Fur is conditionally essential in C. violaceum mainly by protecting cells from iron overload and oxidative damage. The requirement of Fur for virulence highlights the importance of iron in the pathogenesis of C. violaceum IMPORTANCE Maintenance of iron homeostasis, i.e., avoiding both deficiency and toxicity of this metal, is vital to bacteria and their hosts. Iron sequestration by host proteins is a crucial strategy to combat bacterial infections. In bacteria, the ferric uptake regulator Fur coordinates the expression of several iron-related genes. Sometimes, Fur can also regulate several other processes. In this work, we performed an in-depth phenotypic characterization of fur mutants in the human opportunistic pathogen Chromobacterium violaceum We determined that fur is a conditionally essential gene necessary for proper growth under regular conditions and is fully required for survival under iron and oxidative stresses. Fur also controlled several virulence-associated traits, such as swimming motility, biofilm formation, and siderophore production. Consistent with these results, a C. violaceum fur null mutant showed attenuation of virulence. Therefore, our data established Fur as a major player required for C. violaceum to manage iron, including during infection in the host.

Predicting oxidative stress induced by organic chemicals by using quantitative Structure-Activity relationship methods

Cellular exposure to xenobiotic human-made products will lead to oxidative stress that gives rise to DNA damage, as well as chemical or mechanical damage. Distinguishing the chemicals that will induce oxidative stress and predicting their toxicity is necessary. In the present study, 4270 compounds in the ARE-bla assay were investigated to predict active and inactive compounds by using simple algorithms, namely, recursive partitioning (RP) and binomial logistic regression, and to develop the quantitative structure-activity relationship (QSAR) models of chemicals that activate the ARE pathway to induce oxidative stress and exert toxic effects on cells. A decision tree based on scaffold-based fragments obtained through RP analysis showed the best identification accuracy. However, the overall identification accuracy of this model for active compounds was unsatisfactory due to limited fragments. Furthermore, a binomial logistic regression model was developed from 638 active compounds and 3632 inactive chemicals. The model with a cutoff of 0.15 could predict chemicals that were active or inactive with the prediction accuracy of 69.1%. Its area under the receiver operating characteristic (ROC) curve metric (AUROC) was 0.762, which indicated the acceptable predictive ability of this model. The parameters nBM (number of multiple bonds) and H% (percentage of H atom) played dominant roles in the prediction of the activity (inactive or active) of chemicals. A global QSAR model was developed to predict the toxicity of active chemicals. However, the model displayed an unsatisfactory result with R² = 0.316 and R²_ext = 0.090. Active chemicals were then classified on the basis of structure. A total of 79 compounds with carbon chains could be predicted with acceptable performance by using a QSAR model with six descriptors (R² = 0.722, R²_ext = 0.798, Q²_Loo = 0.654, Q²_Boot = 0.755, Q²_ext = 0.721). The simple models established here contribute to efforts on identification compounds inducing oxidative stress and provide the scientific basis for risk assessment to organisms in the environment.

One-pot synthesis of 2,2'-dipicolylamine derived highly photoluminescent nitrogen-doped carbon quantum dots for Fe3+ detection and fingermark detection

The novel nitrogen-doped carbon quantum dots (N-CQDs) with high fluorescence quantum yield of 23.2% were successfully prepared via a simple hydrothermal reaction with citric acid and 2,2'-dipicolylamine. The as-prepared blue fluorescent N-CQDs had excellent water dispersibility, and showed pH and excitation-dependent emission behaviors. Noticeably, owing to the strong interaction between the residual 2,2'-dipicolylamine group on the surface of N-CQDs and Fe³⁺, the N-CQDs could be used as a turn off fluorescence probe for Fe³⁺ sensing through an electron transfer process. Moreover, the photoluminescent N-CQDs/poly(vinyl alcohol) film was further applied for latent fingermark imaging.

Antioxidant Therapies and Oxidative Stress in Friedreich´s Ataxia: The Right Path or Just a Diversion?

Friedreich´s ataxia is the commonest autosomal recessive ataxia among population of European descent. Despite the huge advances performed in the last decades, a cure still remains elusive. One of the most studied hallmarks of the disease is the increased production of oxidative stress markers in patients and models. This feature has been the motivation to develop treatments that aim to counteract such boost of free radicals and to enhance the production of antioxidant defenses. In this work, we present and critically review those "antioxidant" drugs that went beyond the disease´s models and were approved for its application in clinical trials. The evaluation of these trials highlights some crucial aspects of the FRDA research. On the one hand, the analysis contributes to elucidate whether oxidative stress plays a central role or whether it is only an epiphenomenon. On the other hand, it comments on some limitations in the current trials that complicate the analysis and interpretation of their outcome. We also include some suggestions that will be interesting to implement in future studies and clinical trials.

Association between empirically derived dietary patterns and liver function tests in adults: Shahedieh cohort study

OBJECTIVES

Limited data exist on the association between dietary patterns (DPs) and enzymes mainly produced by the liver. This study aimed to examine the relationship between empirically derived DPs and serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and gamma glutamyl transferase (GGT) levels in addition to the alanine/aspartate aminotransferase ratio.

METHODS

This cross-sectional study was conducted on adults in the baseline phase of the Shahedieh cohort study in Yazd, Iran. Blood samples were taken from participants in a fasted state to provide data on dietary intake and other variables. Major DPs were derived using a principal component analysis.

RESULTS

In total, 4973 participants (age 46.33 ± 9.08 y) were included in the study. Three DPs were derived: Traditional diet (high in vegetables, fruits, tomatoes, dairy, dried fruits, fruit juice, yogurt, olive and olive oil, sweet desserts, and high-fat dairy products), western diet (high in pizza, refined grains, soft drinks, high-fat dairy products, processed meats, mayonnaise, and snack foods), and hydrogenated fat and sugar diet (high in hydrogenated fat, potatoes, sugars, and legumes). After adjustment for all confounders, the western DP had a significant linear association with serum GGT (P < 0.001). This diet was also associated with higher odds for developing abnormal levels of serum GGT (P_trend < 0.001). Although the other DPs had some linear associations with enzymes levels, they were not associated with the likelihood for developing abnormally high liver enzymes levels.

CONCLUSIONS

A higher consumption of a western DP might adversely affect serum GGT levels. Prospective studies are recommended to confirm our results.

A novel pyrazole bearing imidazole frame as ratiometric fluorescent chemosensor for Al3+/Fe3+ ions and its application in HeLa cell imaging

New pyrazole bearing imidazole derivative was successfully synthesized and thoroughly characterized by various spectroanalytical techniques. The sensor DIBI shows a highly selective and sensitive fluorescent response with the addition of Al³⁺/Fe³⁺ ions in acetonitrile-water mixture. The strong fluorescent molecule exhibits a notable ratiometric emissions at 462 nm and 470 nm for Al³⁺ and Fe³⁺ ions, respectively (λ_ex = 280 nm). Job's plot studies conclude that the coordination between DIBI with Al³⁺/Fe³⁺ was 1:1 binding stoichiometry. The limit of detection of DIBI with Al³⁺/Fe³⁺ was calculated as 2.12 × 10^-7 M and 1.73 × 10^-6 M, respectively. The TD-DFT calculations further supported the photonics performances of the free probe and its complexes. The reversibility and reusability of the sensor molecule are studied using EDTA. The probe was used to track Al³⁺/Fe³⁺ in cancer cells via fluorescence microscopy.

Magnetic fields enhance the anti-tumor efficacy of low dose cisplatin and reduce the nephrotoxicity

The present work was to examine a combination of therapy for a low dose of cisplatin and a magnetic field (MF) on Ehrlich carcinoma-bearing mice. In this study, a total of 50 BALB/C female mice were equally distributed into five groups. Mice from the control group did not receive MF or cisplatin. The low and high dose cisplatin groups were injected intraperitoneal (i.p.) with 3 and 6 mg/kg cisplatin, respectively, on the experimental days (1, 4, and 8). Mice group of cisplatin + MF was injected with a low dose of cisplatin followed by MF exposure (50 Hz, 50 mT), and the MF group was exposed to MF only. The impact of MF and cisplatin on the tumor and kidney were evaluated by measuring superoxide dismutase (SOD) activity, malondialdehyde (MDA) and glutathione (GSH) levels, DNA injury (comet assay), histopathological investigation of tissues, and tumor progress. The results suggested that the combination of a low dose of cisplatin with MF was significantly elevated in MDA levels, reduced SOD activity, and GSH levels. Furthermore, it caused a rise in comet parameters and inhibition in tumor growth. These results showed that MF enhances the therapeutic efficacy of low cisplatin doses and reduces nephrotoxicity.

A cystine-based dual chemosensor for fluorescent-colorimetric detection of CN- and fluorescent detection of Fe3+ in aqueous media: Synthesis, spectroscopic, and DFT studies

A new dual-responsive chiral cystine based chemosensor, Cys(cou)₂, has been designed and characterized by ¹H NMR, ¹³C NMR, FT-IR, UV-vis as well as elemental analysis. This sensor exhibited an excellent response towards Fe³⁺ and CN^- with high selectivity and sensitivity by fluorescence turn-off mechanism. The binding mode of Cys(cou)₂ with Fe³⁺, and CN^- was confirmed by ESI-MS, ¹H NMR, and fluorescence titration and also quantum chemical calculation. These results showed that the stoichiometric ratio of Cys(cou)₂-Fe³⁺ and Cys(cou)₂-CN is 1:1 and 1:3 in DMSO/Tris aqueous buffer (1:1, v/v), respectively. The linear relationship of the Stern-Volmer plot illustrates the static quenching mechanism at different concentrations. The detection limit (LOD) and binding constant (K_a) for Fe³⁺ and CN^- are 0.029 μM, 1.28 × 10⁴ and 0.51 μM, 9.94 × 10⁶, respectively. Moreover, Cys(cou)₂ can act as a colorimetric sensor for CN^- in DMSO with the color change from colorless to yellow.

Reclassifying Hepatic Cell Death during Liver Damage: Ferroptosis-A Novel Form of Non-Apoptotic Cell Death?

Ferroptosis has emerged as a new type of cell death in different pathological conditions, including neurological and kidney diseases and, especially, in different types of cancer. The hallmark of this regulated cell death is the presence of iron-driven lipid peroxidation; the activation of key genes related to this process such as glutathione peroxidase-4 (gpx4), acyl-CoA synthetase long-chain family member-4 (acsl4), carbonyl reductase [NADPH] 3 (cbr3), and prostaglandin peroxidase synthase-2 (ptgs2); and morphological changes including shrunken and electron-dense mitochondria. Iron overload in the liver has long been recognized as both a major trigger of liver damage in different diseases, and it is also associated with liver fibrosis. New evidence suggests that ferroptosis might be a novel type of non-apoptotic cell death in several liver diseases including non-alcoholic steatohepatitis (NASH), alcoholic liver disease (ALD), drug-induced liver injury (DILI), viral hepatitis, and hemochromatosis. The interaction between iron-related lipid peroxidation, cellular stress signals, and antioxidant systems plays a pivotal role in the development of this novel type of cell death. In addition, integrated responses from lipidic mediators together with free iron from iron-containing enzymes are essential to understanding this process. The presence of ferroptosis and the exact mechanisms leading to this non-apoptotic type of cell death in the liver remain scarcely elucidated. Recognizing ferroptosis as a novel type of cell death in the liver could lead to the understanding of the complex interaction between different types of cell death, their role in progression of liver fibrosis, the development of new biomarkers, as well as the use of modulators of ferroptosis, allowing improved theranostic approaches in the clinic.

The synergy of resveratrol and alcohol against Helicobacter pylori and underlying anti-Helicobacter pylori mechanism of resveratrol

AIMS

To determine individual antibacterial and synergistic antibacterial effects of resveratrol and alcohol against Helicobacter pylori 26695 in vitro, and to elucidate the underlying mechanism of action of resveratrol against H. pylori.

METHODS AND RESULTS

The minimum inhibitory concentrations (MICs) and time-killing curve of resveratrol and alcohol were determined. Transcriptome analysis by RNA sequencing was used to elucidate the underlying mechanism of action of resveratrol against H. pylori. Our results showed that the MICs of resveratrol and alcohol against H. pylori 26695 are about 64 μg ml^-1 and 4% (v/v) respectively. The synergy was found: resveratrol at concentration of 64 μg ml^-1 in combination with alcohol at concentration of 4% (v/v) showed >10 000-fold decrease in the mount of viable bacteria compared with resveratrol and alcohol used alone. Transcriptome analysis showed 152 genes were downregulated and 111 genes were upregulated in the presence of resveratrol. Genes involved in protein translation (17·1%), outer membrane proteins (OMPs) (9·9%) and transports (11·2%) comprise 38·2% of the downregulated genes. In comparison, genes involved in redox (13·5%), pathogenesis and motility (9·9%) and iron homeostasis (4·5%) comprise 27·9% of the upregulated genes.

CONCLUSIONS

The synergy of resveratrol and alcohol against H. pylori was found in this study. The underlying mechanism of action of resveratrol against H. pylori may be mainly attributed to its inhibitory effect on translation, OMPs, transports, ATP synthase and possible oxidative damage.

SIGNIFICANCE AND IMPACT OF THIS STUDY

Our study provides a global insight into the anti-H. pylori mechanism of resveratrol. Both resveratrol and alcohol can contribute to inhibition of ribosomes, changes in OMPs and oxidative damage, which may be the explanations of synergistic effect against H. pylori elicited by resveratrol and alcohol.

Interventions targeted at oxidatively generated modifications of nucleic acids focused on urine and plasma markers

Oxidative stress is associated with the development and progression of numerous diseases. However, targeting oxidative stress has not been established in the clinical management of any disease. Several methods and markers are available to measure oxidative stress, including direct measurement of free radicals, antioxidants, redox balance, and oxidative modifications of cellular macromolecules. Oxidatively generated nucleic acid modifications have attracted much interest due to the pre-mutagenic oxidative modification of DNA into 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), associated with cancer development. During the last decade, the perception of RNA has changed from that of a 'silent messenger' to an 'active contributor', and, parallelly oxidatively generated RNA modifications measured as 8-oxo-7,8-dihydro-guanosine (8-oxoGuo), has been demonstrated as a prognostic factor for all-caused and cardiovascular related mortality in patients with type 2 diabetes. Several attempts have been made to modify the amount of oxidative nucleic acid modifications. Thus, this review aims to introduce researchers to the measurement of oxidatively generated nucleic acid modifications as well as critically review previous attempts and provide future directions for targeting oxidatively generated nucleic acid modifications.

Molecular strategies to increase yeast iron accumulation and resistance

All eukaryotic organisms rely on iron as an essential micronutrient for life because it participates as a redox-active cofactor in multiple biological processes. However, excess iron can generate reactive oxygen species that damage cellular macromolecules. The low solubility of ferric iron under physiological conditions increases the prevalence of iron deficiency anemia. A common strategy to treat iron deficiency consists of dietary iron supplementation. The baker's yeast Saccharomyces cerevisiae is used as a model eukaryotic organism, but also as a feed supplement. In response to iron deficiency, the yeast Aft1 transcription factor activates cellular iron acquisition. However, when constitutively active, Aft1 inhibits growth probably due to iron toxicity. In this report, we have studied the consequences of using hyperactive AFT1 alleles, including AFT1-1UP, to increase yeast iron accumulation. We first characterized the iron sensitivity of cells expressing different constitutively active AFT1 alleles. We rescued the high iron sensitivity conferred by the AFT1 alleles by deleting the sphingolipid signaling kinase YPK1. We observed that the deletion of YPK1 exerts different effects on iron accumulation depending on the AFT1 allele and the environmental iron. Moreover, we determined that the impairment of the high-affinity iron transport system partially rescues the high iron toxicity of AFT1-1UP-expressing cells. Finally, we observed that AFT1-1UP inhibits oxygen consumption through activation of the RNA-binding protein Cth2. Deletion of CTH2 partially rescues the AFT1-1UP negative respiratory effect. Collectively, these results contribute to understand how the Aft1 transcription factor functions and the multiple consequences derived from its constitutive activation.

The Role of Micronutrients in the Infection and Subsequent Response to Hepatitis C Virus

Micronutrient deficiencies develop for a variety of reasons, whether geographic, socioeconomic, nutritional, or as a result of disease pathologies such as chronic viral infection. As micronutrients are essential for a strong immune response, deficiencies can significantly dampen both the innate and the adaptive arms of antiviral immunity. The innate immune response in particular is crucial to protect against hepatitis C virus (HCV), a hepatotropic virus that maintains chronic infection in up to 80% of individuals if left untreated. While many micronutrients are required for HCV replication, an overlapping group of micronutrients are also necessary to enact a potent immune response. As the liver is responsible for the storage and metabolism of many micronutrients, HCV persistence can influence the micronutrients’ steady state to benefit viral persistence both directly and by weakening the antiviral response. This review will focus on common micronutrients such as zinc, iron, copper, selenium, vitamin A, vitamin B12, vitamin D and vitamin E. We will explore their role in the pathogenesis of HCV infection and in the response to antiviral therapy. While chronic hepatitis C virus infection drives deficiencies in micronutrients such as zinc, selenium, vitamin A and B12, it also stimulates copper and iron excess; these micronutrients influence antioxidant, inflammatory and immune responses to HCV.

Specific heme binding to heme regulatory motifs in iron regulatory proteins and its functional significance

Iron regulatory proteins (IRPs) control iron metabolism in mammalian cells by binding to the iron-responsive element (IRE) in the target mRNA. Heme regulatory motifs (HRMs) are conserved in the two IRP homologues IRP1 and IRP2 that specifically bind to two and three heme equivalents, respectively; however, only the heme binding to the iron-dependent degradation (IDD) domain of IRP2 causes heme-mediated oxidation, which does not occur in IRP1. Therefore, the functional significance of conserved HRMs outside the IDD domain is yet unclear. In this study, spectroscopic heme titration with IRP mutants confirmed heme binding to each HRM in IRPs, and the effect of heme binding to HRMs on IRE binding was examined. Native polyacrylamide gel electrophoresis analysis revealed that heme binding to HRMs near the IRE binding site inhibits complex formation between IRPs and IRE without oxidative modification, indicating that the function of HRMs varies outside and within the IDD domain. However, the formation of a typical reactive oxygen species (ROS), hydrogen peroxide, was spectroscopically detected in both heme-bound IRPs. Comparing the heme environmental structures surrounding HRMs, the flexible conformation and many amino acid residues sensitive to ROS of the IDD domain were suggested to promote specific oxidation by the generated hydrogen peroxide. Thus, heme binding to HRM near the IRE binding site sterically interferes with IRE binding, while HRM in the IDD domain facilitates specific heme-mediated oxidation of the protein moiety and the protein degradation via the ubiquitin-proteasome system, resulting in the inhibition of IRE binding.

Hepatocellular Carcinoma Arising in a Non-cirrhotic Liver with Secondary Hemochromatosis

A 70-year-old man was admitted for treatment of a single liver nodule that was detected by contrast-enhanced computed tomography. Twenty years earlier, the patient had been diagnosed with myelodysplastic syndrome-refractory anemia and secondary hemochromatosis but had not received erythrocyte transfusions. The current histological, computed tomography, and magnetic resonance imaging findings revealed hepatocellular carcinoma (HCC) and non-cirrhotic liver hemochromatosis. The liver tumor was treated using radiofrequency ablation therapy. Secondary hemochromatosis may be a risk factor for HCC, even if the liver is not cirrhotic. In such cases, additional surveillance may be required to detect the development of HCC.

Portable and selective colorimetric film and digital image colorimetry for detection of iron

Iron is an important trace element in environmental and biological systems, the development of simple and selective methods for the determination of iron is important. In this work, completely biodegradable tapioca starch was introduced as the substrate to entrap standard chromogenic probes (1,10-phenanthroline) for fabrication of a novel colorimetric sensor for ferrous. A clear plasticized thin film from tapioca starch was fabricated inside a small plastic tube as a portable test kit. A red complex was obtained by exposing the film to a ferrous solution, while no color changes were obtained with various other ions, indicating excellent selectivity. The developed films were applied in conjunction with a digital image colorimetry for quantification of ferrous. Calculated molecular absorption of the red complex showed the widest linear range (0 to 10 mg L^-1) with good linearity (R² < 0.9934) with ferrous concentrations. The developed method provided good inter-day precision (1.75 to 3.97%RSD, 5 days 15 sensors), good accuracy (+2.35% to +4.57% relative error), and low detection limit (0.09 ± 0.01 mg L^-1). The concentrations of ferrous ion in soil and water samples quantified by the developed method were not significantly different from atomic absorption spectrophotometry at 95% confidence level. The films were stable for at least three months.

Development of a fused imidazo[1,2-a]pyridine based fluorescent probe for Fe3+ and Hg2+ in aqueous media and HeLa cells

A new fluorescent sensor 5 having fused imidazopyridine scaffold has been synthesized via cascade cyclization. It exhibits highly sensitive and selective detection of Fe³⁺ (‘turn-on’) and Hg²⁺ (‘turn-off’) in vitro and in HeLa cells.

Hepatocellular Carcinoma in β-Thalassemia Patients: Review of the Literature with Molecular Insight into Liver Carcinogenesis

With the continuing progress in managing patients with thalassemia, especially in the setting of iron overload and iron chelation, the life span of these patients is increasing, while concomitantly increasing incidences of many diseases that were less likely to show when survival was rather limited. Hepatocellular carcinoma (HCC) is a major life-threatening cancer that is becoming more frequently identified in this population of patients. The two established risk factors for the development of HCC in thalassemia include iron overload and viral hepatitis with or without cirrhosis. Increased iron burden is becoming a major HCC risk factor in this patient population, especially in those in the older age group. As such, screening thalassemia patients using liver iron concentration (LIC) measurement by means of magnetic resonance imaging (MRI) and liver ultrasound is strongly recommended for the early detection of iron overload and for implementation of early iron chelation in an attempt to prevent organ-damaging iron overload and possibly HCC. There remain lacking data on HCC treatment outcomes in patients who have thalassemia. However, a personalized approach tailored to each patient’s comorbidities is essential to treatment success. Multicenter studies investigating the long-term outcomes of currently available therapeutic options in the thalassemia realm, in addition to novel HCC therapeutic targets, are needed to further improve the prognosis of these patients.

Hyperbaric oxygen therapy: Antimicrobial mechanisms and clinical application for infections

Hyperbaric oxygen therapy (HBOT) is a treatment procedure that involves breathing 100% O₂ for a certain time and under a certain pressure. HBOT is commonly administrated as a primary or alternative therapy for different diseases such as infections. In this paper, we reviewed the general aspect of HBOT procedures, the mechanisms of antimicrobial effects and the application in the treatment of infections. Parts of the antimicrobial effects of HBOT are believed to result of reactive from the formation of reactive oxygen species (ROS). It is also said that HBOT enhances the antimicrobial effects of the immune system and has an additive or synergistic effect with certain antimicrobial agents. HBOT has been described as a useful procedure for different infections, particularly in deep and chronic infections such as necrotizing fasciitis, osteomyelitis, chronic soft tissue infections, and infective endocarditis. The anti-inflammation property of HBOT has demonstrated that it may play a significant role in decreasing tissue damage and infection expansion. Patients treated by HBOT need carful pre-examination and monitoring. If safety standards are strictly tracked, HBOT can be considered a suitable procedure with an apt rate of complication.

Role for Transferrin in Triggering Apoptosis in Helicoverpa armigera Cells Treated with 2-Tridecanone

2-Tridecanone, a plant allelochemical present in a large range of tomato species ( Lycopersicon hirsutum f. glabratum), can induce the expression of Helicoverpa armigera transferrin ( HaTrf), which is necessary for insect growth and development. To gain further insight into the mechanism of HaTrf in response to 2-tridecanone, we measured the iron and H₂O₂ levels in the hemolymph during exposure to 2-tridecanone and then explored the effect of transferrin downregulation in a H. armigera fat body cell line exposed to 2-tridecanone. We found that the reduction of HaTrf levels via RNA interference caused rapid apoptotic cell death during exposure to 2-tridecanone. There have been no reports about transferrin genes related to apoptosis induced by plant allelochemicals. Our results indicate that HaTrf mediates the inhibition of apoptotic cell death during exposure to 2-tridecanone and provides insight into the importance of transferrin in the interaction between plants and insects.

Protective Role of Histidine Supplementation Against Oxidative Stress Damage in the Management of Anemia of Chronic Kidney Disease

Anemia is a major health condition associated with chronic kidney disease (CKD). A key underlying cause of this disorder is iron deficiency. Although intravenous iron treatment can be beneficial in correcting CKD-associated anemia, surplus iron can be detrimental and cause complications. Excessive generation of reactive oxygen species (ROS), particularly by mitochondria, leads to tissue oxidation and damage to DNA, proteins, and lipids. Oxidative stress increase in CKD has been further implicated in the pathogenesis of vascular calcification. Iron supplementation leads to the availability of excess free iron that is toxic and generates ROS that is linked, in turn, to inflammation, endothelial dysfunction, and cardiovascular disease. Histidine is indispensable to uremic patients because of the tendency toward negative plasma histidine levels. Histidine-deficient diets predispose healthy subjects to anemia and accentuate anemia in chronic uremic patients. Histidine is essential in globin synthesis and erythropoiesis and has also been implicated in the enhancement of iron absorption from human diets. Studies have found that L-histidine exhibits antioxidant capabilities, such as scavenging free radicals and chelating divalent metal ions, hence the advocacy for its use in improving oxidative stress in CKD. The current review advances and discusses evidence for iron-induced toxicity in CKD and the mechanisms by which histidine exerts cytoprotective functions.

Specific colorimetric detection of Fe3+ ions in aqueous solution by squaraine-based chemosensor

A new squaraine based chemosensor TSQ was developed for colorimetric detection of Fe3+ ions. A thymine moiety in TSQ was constructed to act as an ion acceptor. The sensor displayed an instant colorimetric response specific to Fe3+ over the other metal ions in 20% AcOH-H2O solution. The limit of detection was much lower than that of the environmental protection agency guideline (5.37 μM) in drinking water. A 1 : 1 binding between TSQ and Fe3+ ion was evidenced by Job's plot measurement, ESI-MS and Fourier transform infrared (IR) measurements. Moreover, the proposed sensing mechanism of the receptor towards Fe3+ was strongly supported by DFT calculation. Finally, the sensor has proven to be suitable in real sample applications.

Dissecting mRNA decay and translation inhibition during iron deficiency

Iron participates as a vital cofactor in multiple metabolic pathways. Despite its abundance, iron bioavailability is highly restricted in aerobic and alkaline environments. Therefore, living organisms have evolved multiple adaptive mechanisms to respond to iron scarcity. These strategies include a global remodeling of iron metabolism directed to optimize iron utilization. In the baker's yeast Saccharomyces cerevisiae, this metabolic reorganization is accomplished to a large extent by an mRNA-binding protein called Cth2. Yeast Cth2 belongs to a conserved family of tandem zinc finger containing proteins that specifically bind to transcripts with AU-rich elements and promote their turnover. A recent study has revealed that Cth2 also inhibits the translation of its target mRNAs (Ramos-Alonso et al., PLoS Genet 14:e1007476, https://doi.org/10.1371/journal.pgen.1007476 , 2018). Interestingly, the mammalian Cth2 ortholog known as tristetraprolin (aka TTP/TIS11/ZFP36), which is also implicated in controlling iron metabolism, promotes the decay and prevents the translation of its regulated transcripts. These observations open the possibility to study the relative contribution of altering mRNA stability and translation to the physiological adaptation to iron deficiency, the function played by the different domains within the mRNA-binding protein, and the potential factors implicated in coordinating both post-transcriptional events.

Evaluation of iron loading in four types of hepatopancreatic cells of the mangrove crab Ucides cordatus using ferrocene derivatives and iron supplements

The mangrove crab Ucides cordatus is a bioindicator of aquatic contamination. In this work, the iron availability and redox activity of saccharide-coated mineral iron supplements (for both human and veterinary use) and ferrocene derivatives in Saline Ucides Buffer (SUB) medium were assessed. The transport of these metallodrugs by four different hepatopancreatic cell types (embryonic (E), resorptive (R), fibrillar (F), and blister (B)) of U. cordatus were measured. Organic coated iron minerals (iron supplements) were stable against strong chelators (calcein and transferrin). Ascorbic acid efficiently mediated the release of iron only from ferrocene compounds, leading to redox-active species. Ferrous iron and iron supplements were efficient in loading iron to all hepatopancreatic cell types. In contrast, ferrocene derivatives were loaded only in F and B cell types. Acute exposition to the iron compounds resulted in cell viability of 70-95%, and to intracellular iron levels as high as 0.40 μmol L^-1 depending upon the compound and the cell line. The easiness that iron from iron metallodrugs was loaded/transported into U. cordatus hepatopancreatic cells reinforces a cautionary approach to the widespread disposal and use of highly bioavailable iron species as far as the long-term environmental welfare is concerned.

Genotoxic and carcinogenic effects of non-ionizing electromagnetic fields

New technologies in electronics and communications are continually emerging. An increasing use of these electronic devices such as mobile phone, computer, wireless fidelity connectors or cellular towers is raising questions concerning whether they have an adverse effect on the body. Exposure to electromagnetic fields (EMF) is frequently suggested to have adverse health effects on humans and other organisms. This idea has been reported in many studies. In contrast, the therapeutic effects of EMF on different organs have also been reported. Research findings are inconsistent. This has given rise to very profound discrepancies. The duration and frequency of mobile phone calls and the association observed with various health effects has raised serious concerns due to the frequency with which these devices are used and the way they are held close to the head. The present review assesses the results of in vitro, in vivo, experimental, and epidemiological studies. The purpose of the study is to assess data concerning the carcinogenic and genotoxic effects of non-ionizing EMF. The major genotoxic and carcinogenic effects of EMF, divided into subsections as low frequency effects and radiofrequency effects, were reviewed. The inconsistent results between similar studies and the same research groups have made it very difficult to make any comprehensive interpretation. However, evaluation of current studies suggests that EMF may represent a serious source of concern and may be hazardous to living organisms.

HpoR, a novel c-di-GMP effective transcription factor, links the second messenger's regulatory function to the mycobacterial antioxidant defense

Cyclic di-GMP (c-di-GMP) is a global signaling molecule that widely modulates diverse cellular processes. However, whether or not the c-di-GMP signal participates in regulation of bacterial antioxidant defense is unclear, and the involved regulators remain to be explored. In this study, we characterized HpoR as a novel c-di-GMP effective transcription factor and found a link between the c-di-GMP signal and the antioxidant regulation in Mycobacterium smegmatis. H2O2 stress induces c-di-GMP accumulation in M. smegmatis. High level of c-di-GMP triggers expression of a redox gene cluster, designated as hpoR operon, which is required for the mycobacterial H2O2 resistance. HpoR acts as an inhibitor of the hpoR operon and recognizes a 12-bp motif sequence within the upstream regulatory region of the operon. c-di-GMP specifically binds with HpoR at a ratio of 1:1. Low concentrations of c-di-GMP stimulate the DNA-binding activity of HpoR, whereas high concentrations of the signal molecule inhibit the activity. Strikingly, high level of c-di-GMP de-represses the intracellular association of HpoR with the regulatory region of the hpoR operon in M. smegmatis and enhances the mycobacterial H2O2 resistance. Therefore, we report a novel c-di-GMP effective regulator in mycobacteria, which extends the second messenger's function to bacterial antioxidant defense.

An impedimetric biosensor for DNA damage detection and study of the protective effect of deferoxamine against DNA damage

The detection and inhibition of DNA damage are of great importance in the prevention and treatment of diseases. Developing a simple and sensitive tool for this purpose would be a chance to monitor the DNA damage and could be helpful in introducing some drugs which can prevent this phenomenon. Here, we report a novel and sensitive electrochemical biosensor based on DNA/Au nanoparticles (AuNPs) modified screen printed gold electrode (DNA/AuNPs/SPGE) to investigate the DNA damage process and also to study the protective behavior of deferoxamine (DFO). The proposed biosensor was fabricated by electrodeposition of AuNPs onto SPGE, followed by chemical immobilisation of thiol-terminated DNA. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) have been used to characterise this biosensor. Hydroxyl radical (OH), which is generated during the Fenton reaction, is responsible for the induced damage to DNA. EIS technique was applied to monitor the DNA damage, and the increase in charge transfer resistance (R_ct) following the DNA damage, was considered as an indicator. Furthermore, the ability of the electrochemical screening system was proved by the investigation of the antioxidant effect of DFO in prohibiting the DNA damage.

A dual-responsive colorimetric and fluorescent chemosensor based on diketopyrrolopyrrole derivative for naked-eye detection of Fe3+ and its practical application

A novel dual-responsive colorimetric and fluorescent chemosensor L based on diketopyrrolopyrrole derivative for Fe³⁺ detection was designed and synthesized. In presence of Fe³⁺, sensor L displayed strong colorimetric response as amaranth to rose pink and significant fluorescence enhancement and chromogenic change, which served as a naked-eye indicator by an obvious color change from purple to red. The binding constant for L-Fe³⁺ complex was found as 2.4×10⁴ with the lower detection limit of 14.3nM. The sensing mechanism was investigated in detail by fluorescence measurements, IR and ¹H NMR spectra. Sensor L for Fe³⁺ detection also exhibited high anti-interference performance, good reversibility, wide pH response range and instantaneous response time. Furthermore, the sensor L has been used to quantify Fe³⁺ ions in practical water samples with good recovery.

FreB is involved in the ferric metabolism and multiple pathogenicity-related traits of Verticillium dahliae

Ferric reductases are integral membrane proteins involved in the reduction of environmental ferric iron into the biologically available ferrous iron. In the most overwhelming phytopathogenic fungus, Verticillium dahliae, these ferric reductase are not studied in details. In this study we explored the role of FreB gene (VDAG_06616) in the ferric reduction and virulence of V. dahliae by generating the knockout mutants (ΔFreB) and complementary strains (ΔFreB-C) using protoplast transformation. When cultured on media supplemented with FeSO₄, FeCl₃ and no iron, ΔFreB exhibited significantly reduced growth and spore production especially on media with no iron. Transmembrane ferric reductase activity of ΔFreB was decreased up to 50% than wild type strains (Vd-wt). The activity was fully restored in ΔFreB-C. Meanwhile, the expression levels of other related genes (Frect-4, Frect-5, Frect-6 and Met) were obviously increased in ΔFreB. Compared with the Vd-wt and ΔFreB-C, ΔFreB-1 and ΔFreB-2 were impaired in colony diameter and spore number on different carbon sources (starch, sucrose, galactose and xylose). ΔFreB-1 and ΔFreB-2 were also highly sensitive to oxidative stress as revealed by the plate diffusion assay when 100 µM H₂O₂ was applied to the fungal culture. When Nicotiana benthamiana plants were inoculated, ΔFreB exhibited less disease symptoms than Vd-wt and ΔFreB-C. In conclusion, the present findings not only indicate that FreB mediates the ferric metabolism and is required for the full virulence in V. dahliae, but would also accelerate future investigation to uncover the pathogenic mechanism of this fungus.

Function of glutaredoxin 3 (Grx3) in oxidative stress response caused by iron homeostasis disorder in Candida albicans

Aim: Glutaredoxin is a conserved oxidoreductase in eukaryotes and prokaryotes. This study aimed to determine the role of Grx3 in cell survival, iron homeostasis and the oxidative stress response in Candida albicans. Materials & methods: A grx3Δ/Δ mutant was obtained using PCR-mediated homologs recombination. The function of Grx3 was investigated by a series of biochemical methods. Results: Deletion of GRX3 impaired growth and cell cycle, disturbance of iron homeostasis and activated the oxidative stress response. Furthermore, disruption of GRX3 caused oxidative damage and growth defects of C. albicans. Conclusion: Our findings provide new insights into the role of GRX3 in C. albicans.

Photoinduced Electron Transfer Switching Mechanism of a Naphthalimide Derivative with its Solvatochromic Behaviour: An Experimental and Theoretical Study with In Cell Investigations

The sole existence of a t-bone-shaped naphthalimide derivative [2-(2-aminoethyl)-1H-benzo[de]isoquinoline-1,3(2H)dione] (NAP), which gives rise to a photoinduced electron transfer (PET) mechanism, has been established using a combination of experimental and theoretical studies. In parallel an in vitro-in cell PET mechanism has also been shown. To understand the photophysics of NAP, solvent studies have been carried out in different solvents. In addition, theoretical calculations have been conducted to explain the spectroscopic properties through optimized structures. A "turn off" PET mechanism has also been observed in the presence of specific metal ions, namely, Cr³⁺ , Fe³⁺ and Hg²⁺ among a series of metal ions. Theoretical studies reveal that NAP-Cr³⁺ , NAP-Fe³⁺ and NAP-Hg²⁺ have their HOMO energy states lying in between a HOMO-LUMO energy state of the t-bone-type NAP molecule. On the contrary, the HOMO state of the other metal ion-NAP conjugate (NAP-Mⁿ⁺ ) does not lie in between the HOMO-LUMO energy gap of the t-bone-type NAP molecule. Coupled with in vitro studies, in cell investigations reveal an enhancement of fluorescence intensity of NAP upon cytosolic metal sensing. Furthermore, a very high cell viability of NAP treated cells as tested by MTT assay and a fast permeation of the said compound as revealed by flow cytometry suggest NAP to be a potential candidate in metal sensing and bioimaging applications.

Photometric flow analysis system for biomedical investigations of iron/transferrin speciation in human serum

The Multicommutated Flow Analysis (MCFA) system for the estimation of clinical iron parameters: Serum Iron (SI), Unsaturated Iron Binding Capacity (UIBC) and Total Iron Binding Capacity (TIBC) has been proposed. The developed MCFA system based on simple photometric detection of iron with chromogenic agent (ferrozine) enables a speciation of transferrin (determination of free and Fe-bound protein) in human serum. The construction of manifold was adapted to the requirements of measurements under changing conditions. In the course of studies, a different effect of proteins on SI and UIBC determination has been proven. That was in turn the reason to perform two kinds of calibration methods. For measurements in acidic medium for SI/holotransferrin determination, the calibration curve method was applied, characterized by limit of determination and limit of quantitation on the level of 3.4 μmol L^-1 and 9.1 μmol L^-1, respectively. The determination method for UIBC parameter (related to apotransferrin level) in physiological medium of pH 7.4 forced the use of standard addition method due to the strong influence of proteins on obtaining analytical signals. These two different methodologies, performed in the presented system, enabled the estimation of all three clinical iron/transferrin parameters in human serum samples. TIBC corresponding to total transferrin level was calculated as a sum of SI and UIBC.

Biodegradable Core-shell Dual-Metal-Organic-Frameworks Nanotheranostic Agent for Multiple Imaging Guided Combination Cancer Therapy

Metal-organic-frameworks (MOFs) possess high porosity, large surface area, and tunable functionality are promising candidates for synchronous diagnosis and therapy in cancer treatment. Although large number of MOFs has been discovered, conventional MOF-based nanoplatforms are mainly limited to the sole MOF source with sole functionality. In this study, surfactant modified Prussian blue (PB) core coated by compact ZIF-8 shell (core-shell dual-MOFs, CSD-MOFs) has been reported through a versatile stepwise approach. With Prussian blue as core, CSD-MOFs are able to serve as both magnetic resonance imaging (MRI) and fluorescence optical imaging (FOI) agents. We show that CSD-MOFs crystals loading the anticancer drug doxorubicin (DOX) are efficient pH and near-infrared (NIR) dual-stimuli responsive drug delivery vehicles. After the degradation of ZIF-8, simultaneous NIR irradiation to the inner PB MOFs continuously generate heat that kill cancer cells. Their efficacy on HeLa cancer cell lines is higher compared with the respective single treatment modality, achieving synergistic chemo-thermal therapy efficacy. In vivo results indicate that the anti-tumor efficacy of CSD-MOFs@DOX+NIR was 7.16 and 5.07 times enhanced compared to single chemo-therapy and single thermal-therapy respectively. Our strategy opens new possibilities to construct multifunctional theranostic systems through integration of two different MOFs.

Role of Total, Red, Processed, and White Meat Consumption in Stroke Incidence and Mortality: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

Background

Previous meta‐analyses on meat intake and risk of stroke did not report the effect of white meat (poultry meat, excluding fish) and did not examine stroke incidence and mortality separately. We aimed to investigate the relationship of total (red and processed meat), red (unprocessed or fresh red meat), and processed (processed red meat) consumption along with white meat on risk of stroke incidence and mortality.

Methods and Results

Articles were identified from databases and reference lists of relevant studies up to October 28, 2016. We selected prospective cohort studies on meat consumption specified by types of meat and stroke incidence and mortality reporting relative risks and 95% confidence intervals. The pooled relative risk was estimated using the random‐effects model. Based on the inclusion criteria, 10 articles containing 15 studies (5 articles with 7 studies including 9522 cases of stroke incidence and 254 742 participants and 5 articles with 8 studies containing 12 999 cases of stroke mortality and 487 150 participants) were selected for quantitative synthesis. The pooled relative risks (95% confidence intervals) for total, red, processed and white meat consumption and total stroke incidence were 1.18 (1.09–1.28), 1.11 (1.03–1.20), 1.17 (1.08–1.25), and 0.87 (0.78–0.97), respectively. Total meat consumption (0.97 [0.85–1.11]) and red meat consumption 0.87 (0.64–1.18) were not significantly associated with stroke‐related death.

Conclusions

The relationship between meat intake and risk of stroke may differ by type of meat. Recommendations for replacing proportions of red and processed meats to white meat for the prevention of stroke may be considered in clinical practice.