Unifying electrostatic mechanism for metal cations in receptors and cell signaling

Biological effects of magnetic fields emitted by graphene devices, on induced oxidative stress in human cultured cells

Many recent studies have explored the healing properties of the extremely low-frequency electromagnetic field (ELF-EMF) to utilize electromagnetism for medical purposes. The non-invasiveness of electromagnetic induction makes it valuable for supportive therapy in various degenerative pathologies with increased oxidative stress. To date, no harmful effects have been reported or documented. We designed a small, wearable device which does not require a power source. The device consists of a substrate made of polyethylene terephthalate and an amalgam containing primarily graphene nanocrystals, also known as quantum dots. This device can transmit electromagnetic signals, which could induce biological effects. This study aims to verify the preliminary effects of the electromagnetic emission of the device on leukemic cells in culture. For this purpose, we studied the best-known effects of magnetic fields on biological models, such as cell viability, and the modulations on the main protagonists of cellular oxidative stress.

Acid-Switchable DNAzyme Nanodevice for Imaging Multiple Metal Ions in Living Cells

Metal-assisted deoxyribozyme catalysis (DNAzyme) has been a general platform for constructing highly sensitive and selective detection sensors of metal ions. However, the "always on" mode of the traditional DNAzyme sensors greatly limits their application in the visual analysis of endogenous metal ions in a complex physiological microenvironment. To overcome this obstacle, a smart acid-switchable DNAzyme nanodevice is designed to control the DNAzyme activity in living cells and achieve simultaneous visualization of metal ions (Zn²⁺ and Pb²⁺) in situ. This nanodevice is built on DNAzyme precursors (DPs) and acid-switchable DNA (SW-DNA), precisely responding to pH variations in the range of 4.5-7.0, and the state of the three-strand hybridization of DPs successfully renders the DNAzymes inactive before being transported into cells. Once the nanodevice is taken up into living cells, the SW-DNA will change the configuration from linear to triplex in the acidic intracellular compartments (lysosomes, pH ∼4.5 to 5.0) and then the strands hybridized with the SW-DNA are liberated and subsequently react with DPs to form the active DNAzyme, which can further realize multi-imaging of intracellular metal ions. Moreover, this strategy has broad prospects as a powerful platform for constructing various acid-switchable nanodevices for visual analysis of multiple biomolecules in living cells.

NIR Remote-Controlled "Lock-Unlock" Nanosystem for Imaging Potassium Ions in Living Cells

Despite great achievements in sensitive and selective detection of important biomolecules in living cells, it is still challenging to develop smart and controllable sensing nanodevices for cellular studies that can be activated at desired time in target sites. To address this issue, we have constructed a remote-controlled "lock-unlock" nanosystem for visual analysis of endogenous potassium ions (K⁺), which employed a dual-stranded aptamer precursor (DSAP) as recognition molecules, SiO₂ based gold nanoshells (AuNS) as nanocarriers, and near-infrared ray (NIR) as the remotely applied stimulus. With the well-designed and activatable DSAP-AuNS, the deficiencies of traditional aptamer-based sensors have been successfully overcome, and the undesired response during transport has been avoided, especially in complex physiological microenvironments. While triggered by NIR, the increased local temperature of AuNS induced the dehybridiztion of DSAP, realized the "lock-unlock" switch of the DSAP-AuNS nanosystem, activated the binding capability of aptamer, and then monitored intracellular K⁺ via the change of fluorescence signal. This DSAP-AuNS nanosystem not only allows us to visualize endogenous ions in living cells at a desired time but also paves the way for fabricating temporal controllable nanodevices for cellular studies.

Moderate Dose of Trolox Preventing the Deleterious Effects of Wi-Fi Radiation on Spermatozoa In vitro through Reduction of Oxidative Stress Damage

Background:

The worsening of semen quality, due to the application of Wi-Fi, can be ameliorated by Vitamin E. This study aimed to demonstrate whether a moderate dose of trolox, a new Vitamin E, inhibits oxidative damage on sperms in vitro after exposure to Wi-Fi radiation.

Methods:

Each of the twenty qualified semen, gathered from June to October 2014 in eugenics clinic, was separated into four aliquots, including sham, Wi-Fi-exposed, Wi-Fi plus 5 mmol/L trolox, and Wi-Fi plus 10 mmol/L trolox groups. At 0 min, all baseline parameters of the 20 samples were measured in sequence. Reactive oxygen species, glutathione, and superoxide dismutase were evaluated in the four aliquots at 45 and 90 min, as were sperm DNA fragments, sperm mitochondrial potential, relative amplification of sperm mitochondrial DNA, sperm vitality, and progressive and immotility sperm. The parameters were analyzed by one-way analysis of variance and Tukey's posttest.

Results:

Among Wi-Fi plus 5 mmol/L trolox, Wi-Fi-exposed and Wi-Fi plus 10 mmol/L trolox groups, reactive oxygen species levels (45 min: 3.80 ± 0.41 RLU·10⁻⁶·ml⁻¹ vs. 7.50 ± 0.35 RLU·10⁻⁶·ml⁻¹ vs. 6.70 ± 0.47 RLU·10⁻⁶·ml⁻¹, P < 0.001; 90 min: 5.40 ± 0.21 RLU·10⁻⁶·ml⁻¹ vs. 10.10 ± 0.31 RLU·10⁻⁶·ml⁻¹ vs. 7.00 ± 0.42 RLU·10⁻⁶·ml⁻¹, P < 0.001, respectively), percentages of tail DNA (45 min: 16.8 ± 2.0% vs. 31.9 ± 2.5% vs. 61.3 ± 1.6%, P < 0.001; 90 min: 19.7 ± 1.5% vs. 73.7 ± 1.3% vs. 73.1 ± 1.1%, P < 0.001, respectively), 8-hydroxy-2’-deoxyguanosine (45 min: 51.89 ± 1.46 pg/ml vs. 104.89 ± 2.19 pg/ml vs. 106.11 ± 1.81 pg/ml, P = 0.012; 90 min: 79.96 ± 1.73 pg/ml vs. 141.73 ± 2.90 pg/ml vs. 139.06 ± 2.79 pg/ml; P < 0.001), and percentages of immotility sperm (45 min: 27.7 ± 2.7% vs. 41.7 ± 2.2% vs. 41.7 ± 2.5%; 90 min: 29.9 ± 3.3% vs. 58.9 ± 4.0% vs. 63.1 ± 4.0%; all P < 0.001) were lowest, and glutathione peroxidase (45 min: 60.50 ± 1.54 U/ml vs. 37.09 ± 1.77 U/ml vs. 28.18 ± 1.06 U/ml; 90 min: 44.61 ± 1.23 U/ml vs. 16.86 ± 0.93 U/ml vs. 29.94 ± 1.56 U/ml; all P < 0.001), percentages of head DNA (45 min: 83.2 ± 2.0% vs. 68.2 ± 2.5% vs. 38.8 ± 1.6%; 90 min: 80.3 ± 1.5% vs. 26.3 ± 1.3% vs. 26.9 ± 1.1%; all P < 0.001), percentages of sperm vitality (45 min: 89.5 ± 1.6% vs. 70.7 ± 3.1% vs. 57.7 ± 2.4%; 90 min: 80.8 ± 2.2% vs. 40.4 ± 4.0% vs. 34.7 ± 3.9%; all P < 0.001), and progressive sperm (45 min: 69.3 ± 2.7% vs. 55.8 ± 2.2% vs. 55.4 ± 2.5%; 90 min: 67.2 ± 3.3% vs. 38.2 ± 4.0% vs. 33.9 ± 4.0%; all P < 0.001) were highest in Wi-Fi plus 5 mmol/L trolox group at 45 and 90 min, respectively. Other parameters were not affected, while the sham group maintained the baseline.

Conclusion:

This study found that 5 mmol/L trolox protected the Wi-Fi-exposed semen in vitro from the damage of electromagnetic radiation-induced oxidative stress.

Novel electrostatic mechanism for mode of action by N-acetylated proteins: cell signaling and phosphorylation

Although extensive literature exists for N-acetylated proteins, scant knowledge is available concerning resultant mode of action. This review presents a novel mechanism based on electrostatics and cell signaling. There is substantial increase in the amide dipole and electrostatic field (EF) in contrast with the primary amino of the lysine precursor. The EF might serve as a bridge in electron transfer and cell signaling or energetics may play a role. The relationship between N-acetylation and phosphorylation is addressed. EFs may be important in the case of phosphates. Involvement of cell signaling is addressed including mechanistic aspects. As is the case for many aspects of bioaction, an integrated approach involving electrochemistry and cell signaling seems reasonable.

Zolpidem, a clinical hypnotic that affects electronic transfer, alters synaptic activity through potential GABA receptors in the nervous system without significant free radical generation

Zolpidem (trade name Ambien) has attracted much interest as a sleep-inducing agent and also in research. Attention has been centered mainly on receptor binding and electrochemistry in the central nervous system which are briefly addressed herein. A novel integrated approach to mode of action is presented. The pathways to be discussed involve basicity, reduction potential, electrostatics, cell signaling, GABA receptor binding, electron transfer (ET), pharmacodynamics, structure activity relationships (SAR) and side effects. The highly conjugated pyridinium salt formed by protonation of the amidine moiety is proposed to be the active form acting as an ET agent. Extrapolation of reduction potentials for related compounds supports the premise that zolpidem may act as an ET species in vivo. From recent literature reports, electrostatics is believed to play a significant role in drug action.

The pyridinium cation displays molecular electrostatic potential which may well play a role energetically or as a bridging mechanism. An SAR analysis points to analogy with other physiologically active xenobiotics, namely benzodiazepines and paraquat in the conjugated iminium category. Inactivity of metabolites indicates that the parent is the active form of zolpidem. Absence of reactive oxygen species and oxidative stress is in line with minor side effects. In contrast, generally, the prior literature contains essentially no discussion of these fundamental biochemical relationships. Pharmacodynamics may play an important role. Concerning behavior at the blood-brain barrier, useful insight can be gained from investigations of the related cationic anesthetics that are structurally related to acetyl choline. Evidently, the neutral form of the drug penetrates the neuronal membrane, with the salt form operating at the receptor. The pathways of zolpidem have several clinical implications since the agent affects sedation, electroencephalographic activity, oxidative metabolites and receptors in the central nervous system. The drug acts at the GABA(A) receptor benzodiazepine site, displaying high and intermediate affinities to various receptor regions. Structural features for tight binding were determined. The sedative and anticonvulsant activities are due to its action on the alpha-1-GABA(A) receptors. One of the common adverse responses to zolpidem is hallucinations. Proposed mechanisms comprise changes in the GABA(A) receptor, pharmacodynamic interactions involving serotonin and neuronal-weak photon emission processes entailing redox phenomena. Reports cite cases of abuse with cravings based on anxiolytic and stimulating actions. It is important to recognize that insight concerning processes at the fundamental, molecular level can translate into beneficial results involving both positive and adverse side effects. In order for this to occur, interdisciplinary interaction is necessary. Suggestions are made for future research aimed at testing the various hypotheses.

Multifaceted approach to resveratrol bioactivity: Focus on antioxidant action, cell signaling and safety

Resveratrol (RVT) is a naturally occurring trihydroxy stilbene that displays a wide spectrum of physiological activity. Its ability to behave therapeutically as a component of red wine has attracted wide attention. The phenol acts as a protective agent involving various body constituents. Most attention has been given to beneficial effects in insults involving cancer, aging, cardiovascular system, inflammation and the central nervous system. One of the principal modes of action appears to be as antioxidant. Other mechanistic pathways entail cell signaling, apoptosis and gene expression. There is an intriguing dichotomy in relation to pro-oxidant property. Also discussed are metabolism, receptor binding, rationale for safety and suggestions for future work. This is the first comprehensive review of RVT based on a broad, unifying mechanism.

Glycosaminoglycan sulphation affects the seeded misfolding of a mutant prion protein

Background

The accumulation of protease resistant conformers of the prion protein (PrP^res) is a key pathological feature of prion diseases. Polyanions, including RNA and glycosaminoglycans have been identified as factors that contribute to the propagation, transmission and pathogenesis of prion disease. Recent studies have suggested that the contribution of these cofactors to prion propagation may be species specific.

Methodology/Principal Finding

In this study a cell-free assay was used to investigate the molecular basis of polyanion stimulated PrP^res formation using brain tissue or cell line derived murine PrP. Enzymatic depletion of endogenous nucleic acids or heparan sulphate (HS) from the PrP^C substrate was found to specifically prevent PrP^res formation seeded by mouse derived PrP^Sc. Modification of the negative charge afforded by the sulphation of glycosaminoglycans increased the ability of a familial PrP mutant to act as a substrate for PrP^res formation, while having no effect on PrP^res formed by wildtype PrP. This difference may be due to the observed differences in the binding of wild type and mutant PrP for glycosaminoglycans.

Conclusions/Significance

Cofactor requirements for PrP^res formation are host species and prion strain specific and affected by disease associated mutations of the prion protein. This may explain both species and strain dependent propagation characteristics and provide insights into the underlying mechanisms of familial prion disease. It further highlights the challenge of designing effective therapeutics against a disease which effects a range of mammalian species, caused by range of aetiologies and prion strains.