New insight into the biocompatibility/toxicity of graphene oxides and their reduced forms on Chlamydomonas reinhardtii

Graphene oxides (GOs) and their reduced forms are often discussed both positively and negatively due to the lack of information about their chemistry and structure. This study utilized GOs with two sheet sizes that were further reduced by two reducing agents (sodium borohydride and hydrazine) to obtain two different degrees of reduction. The synthesized nanomaterials were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), elemental analysis (EA), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy (RA) to understand their chemistry and structure. The second focus of our investigation included in vitro testing of the biocompatibility/toxicity of these materials on a model organism, the freshwater microalga Chlamydomonas reinhardtii. The effects were studied on the basis of biological endpoints complemented by biomass investigation (FTIR spectroscopy, EA, and atomic absorption spectrometry (AAS)). The results showed that the biocompatibility/toxicity of GOs is dependent on their chemistry and structure and that it is impossible to generalize the toxicity of graphene-based nanomaterials.

Surface modification strategies and the functional mechanisms of gold nanozyme in biosensing and bioassay

Gold nanozymes (GNZs) have been widely used in biosensing and bioassay due to their interesting catalytic activities that enable the substitution of natural enzyme. This review explains different catalytic activities of GNZs that can be achieved by applying different modifications to their surface. The role of Gold nanoparticles (GNPs) in mimicking oxidoreductase, helicase, phosphatase were introduced. Moreover, the effect of surface properties and modifications on each catalytic activity was thoroughly discussed. The application of GNZs in biosensing and bioassay was classified in five categories based on the combination of the enzyme like activities and enhancing/inhibition of the catalytic activities in presence of the target analyte/s that is realized by proper surface modification engineering. These categories include catalytic activity enhancer, reversible catalytic activity inhibitor, binding selectivity enhancer, agglomeration base, and multienzyme like activity, which are explained and exemplified in this review. It also gives examples of those modifications that enable the application of GNZs for in vivo biosensing and bioassays.

Selected ginsenosides interfere efficiently with hepatitis B virus mRNA expression levels and suppress viral surface antigen secretion

Ginsenosides are a class of natural steroid glycosides and triterpene saponins found in Panax ginseng. After screening of a commercial ginsenoside compound library for low cellular cytotoxicity and the ability to mediate efficient reductions in hepatitis B virus (HBV) mRNA expression levels in HepG2.2.15 cells, three ginsenosides (Rg6, Rh4, and Rb3) are selected. Thereafter, using the same cellular model, all three ginsenosides are shown to mediate efficient, selective inhibition of HBV mRNA expression levels, and also interfere with the secretion of both HBV particles and hepatitis B surface antigen (HBsAg). Drug combination studies are performed in both HepG2.2.15 and HBV-infected HepG2-NTCPsec+ cell models with the selected ginsenosides and lamivudine (LMV), a nucleoside analogue used to treat chronic hepatitis B (CHB) infections. These studies, involving RT-qPCR and ELISA, suggest that Rh4/LMV combinations in particular act synergistically to inhibit the secretion of HBV particles and HBsAg. Therefore, on the assumption that appropriate in vivo data are in future agreement, Rh4, in particular, might be used in combination with nucleoside/nucleotide analogues (NUCs) to devise an effective, cost-efficient combination therapy for the treatment of patients with CHB infections.

Quantum Dots in Peroxidase-like Chemistry and Formamide-Based Hot Spring Synthesis of Nucleobases

Quantum dots (QDs) are usually seen as artificial semiconductor particles exhibiting optical and electronic properties interesting for nanotechnological applications. However, they may also play a role in prebiotic chemistry. Starting from zinc acetate, cadmium acetate, and mercaptosuccinic acid, we demonstrate the formation of ZnCd QDs upon UV irradiation in prebiotic liquid formamide. We show that ZnCd QDs are able to increase the yield of RNA nucleobase synthesis from formamide up to 300 times, suggesting they might have served as universal catalysts in a primordial milieu. Based on the experimentally observed peroxidase-like activity of ZnCd QDs upon irradiation with visible light, we propose that QDs could be relevant to a broad variety of processes relating to the emergence of terrestrial life.

Mutual influence of selenium nanoparticles and FGF2-STAB® on biocompatible properties of collagen/chitosan 3D scaffolds: in vitro and ex ovo evaluation

In a biological system, nanoparticles (NPs) may interact with biomolecules. Specifically, the adsorption of proteins on the nanoparticle surface may influence both the nanoparticles' and proteins' overall bio-reactivity. Nevertheless, our knowledge of the biocompatibility and risk of exposure to nanomaterials is limited. Here, in vitro and ex ovo biocompatibility of naturally based crosslinked freeze-dried 3D porous collagen/chitosan scaffolds, modified with thermostable fibroblast growth factor 2 (FGF2-STAB®), to enhance healing and selenium nanoparticles (SeNPs) to provide antibacterial activity, were evaluated. Biocompatibility and cytotoxicity were tested in vitro using normal human dermal fibroblasts (NHDF) with scaffolds and SeNPs and FGF2-STAB® solutions. Metabolic activity assays indicated an antagonistic effect of SeNPs and FGF2-STAB® at high concentrations of SeNPs. The half-maximal inhibitory concentration (IC50) of SeNPs for NHDF was 18.9 µg/ml and IC80 was 5.6 µg/ml. The angiogenic properties of the scaffolds were monitored ex ovo using a chick chorioallantoic membrane (CAM) assay and the cytotoxicity of SeNPs over IC80 value was confirmed. Furthermore, the positive effect of FGF2-STAB® at very low concentrations (0.01 µg/ml) on NHDF metabolic activity was observed. Based on detailed in vitro testing, the optimal concentrations of additives in the scaffolds were determined, specifically 1 µg/ml of FGF2-STAB® and 1 µg/ml of SeNPs. The scaffolds were further subjected to antimicrobial tests, where an increase in selenium concentration in the collagen/chitosan scaffolds increased the antibacterial activity. This work highlights the antimicrobial ability and biocompatibility of newly developed crosslinked collagen/chitosan scaffolds involving FGF2-STAB® and SeNPs. Moreover, we suggest that these sponges could be used as scaffolds for growing cells in systems with low mechanical loading in tissue engineering, especially in dermis replacement, where neovascularization is a crucial parameter for successful skin regeneration. Due to their antimicrobial properties, these scaffolds are also highly promising for tissue replacement requiring the prevention of infection.

Synergistic Effect of Chitosan and Selenium Nanoparticles on Biodegradation and Antibacterial Properties of Collagenous Scaffolds Designed for Infected Burn Wounds

A highly porous scaffold is a desirable outcome in the field of tissue engineering. The porous structure mediates water-retaining properties that ensure good nutrient transportation as well as creates a suitable environment for cells. In this study, porous antibacterial collagenous scaffolds containing chitosan and selenium nanoparticles (SeNPs) as antibacterial agents were studied. The addition of antibacterial agents increased the application potential of the material for infected and chronic wounds. The morphology, swelling, biodegradation, and antibacterial activity of collagen-based scaffolds were characterized systematically to investigate the overall impact of the antibacterial additives. The additives visibly influenced the morphology, water‑retaining properties as well as the stability of the materials in the presence of collagenase enzymes. Even at concentrations as low as 5 ppm of SeNPs, modified polymeric scaffolds showed considerable inhibition activity towards Gram-positive bacterial strains such as Staphylococcus aureus and methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis in a dose-dependent manner.

A274 EARLY SINGLE-OPERATOR CHOLANGIOSCOPY ASSISTED ELECTROHYDRAULIC LITHOTRIPSY (SOC-EHL) IN THE MANAGEMENT OF DIFFICULT BILIARY STONES IS COST-EFFECTIVE WHEN COMPARED TO A DELAYED STEP-UP APPROACH TO LATER SOC-EHL

Background

Single-operator cholangioscopy assisted electrohydraulic lithotripsy is the standard of care for difficult common bile duct (CBD) stones with failed clearance using standard ERCP. This technology is expensive and optimal timing of its use in terms of cost-effectiveness in the management algorithm of patients with difficult CBD stones remains unclear

Aims

To determine the cost-effective timing of SOC-EHL utilization in the management of difficult CBD stones

Methods

A decision model was developed assessing 4 strategies and progressively delayed introduction of SOC-EHL in relation to ERCP over 6-months. Difficult stones were defined as having failed CBD clearance via standard ERCP. Probability estimates for each health state were obtained from a literature systematic review. For each strategy, outpatients undergoing ERCP underwent different timings of SOC-EHL introduction from the first to the fourth ERCP and were followed for subsequent need for re-intervention, adverse events, need for surgery, and/or successful endoscopic CBD clearance. The unit of effectiveness was complete CBD clearance without need for surgery. Deterministic sensitivity analyses were performed varying all 50 model variables across ranges spanning 30% of their respective values. Costs are in 2018US$ based on US data.

Results

Performing SOC-EHL immediately during the first ERCP is the least expensive approach when compared to delaying SOC-EHL. This strategy costs $15,528 on average per patient with CBD clearance avoiding surgery and can save between $260 to $720 compared to the 3 other strategies, which introduce SOC-EHL during the second to the fourth ERCP. Effectiveness is clinically comparable between the four strategies ranging from 97–99%. Deterministic sensitivity analysis shows changes in the results when the ERCP complication rate (baseline probability of 6%) decreases to 4.5%, when the SOC-EHL (baseline costs of $2,450) costs more than $2,670, or when the ERCP facility fees (baseline costs of $4,292) are less than $3,425. In all 3 scenarios, delaying the first SOC-EHL use to the fourth procedural attempt becomes the dominant strategy. Variations of the other 47 variables did not alter results.

Conclusions

Although SOC-EHL is expensive, this analysis demonstrates that among patients who have failed a prior attempt at stone extraction, utilization of SOC-EHL at the next (first subsequent) ERCP is less costly when compared to its delayed introduction. However, postponing the use of SOC-EHL to the fourth ERCP could be identified as the most cost-effective strategy when facility fees or ERCP complications rates are below certain thresholds, or when the costs of SOC-EHL extend beyond a defined threshold.

Funding Agencies

None

Cytochrome P450 and flavin-containing monooxygenase enzymes are responsible for differential oxidation of the anti-thyroid-cancer drug vandetanib by human and rat hepatic microsomal systems

We studied the in vitro metabolism of the anti-thyroid-cancer drug vandetanib in a rat animal model and demonstrated that N-desmethylvandetanib and vandetanib N-oxide are formed by NADPH- or NADH-mediated reactions catalyzed by rat hepatic microsomes and pure biotransformation enzymes. In addition to the structural characterization of vandetanib metabolites, individual rat enzymes [cytochrome P450 (CYP) and flavin-containing monooxygenase (FMO)] capable of oxidizing vandetanib were identified. Generation of N-desmethylvandetanib, but not that of vandetanib N-oxide, was attenuated by CYP3A and 2C inhibitors while inhibition of FMO decreased formation of vandetanib N-oxide. These results indicate that liver microsomal CYP2C/3A and FMO1 are major enzymes participating in the formation of N-desmethylvandetanib and vandetanib N-oxide, respectively. Rat recombinant CYP2C11 > >3A1 > 3A2 > 1A1 > 1A2 > 2D1 > 2D2 were effective in catalyzing the formation of N-desmethylvandetanib. Results of the present study explain differences between the CYP- and FMO-catalyzed vandetanib oxidation in rat and human liver reported previously and the enzymatic mechanisms underlying this phenomenon.

Identification of Human Enzymes Oxidizing the Anti-Thyroid-Cancer Drug Vandetanib and Explanation of the High Efficiency of Cytochrome P450 3A4 in its Oxidation

The metabolism of vandetanib, a tyrosine kinase inhibitor used for treatment of symptomatic/progressive medullary thyroid cancer, was studied using human hepatic microsomes, recombinant cytochromes P450 (CYPs) and flavin-containing monooxygenases (FMOs). The role of CYPs and FMOs in the microsomal metabolism of vandetanib to N-desmethylvandetanib and vandetanib-N-oxide was investigated by examining the effects of CYP/FMO inhibitors and by correlating CYP-/FMO-catalytic activities in each microsomal sample with the amounts of N-desmethylvandetanib/vandetanib-N-oxide formed by these samples. CYP3A4/FMO-activities significantly correlated with the formation of N-desmethylvandetanib/ vandetanib-N-oxide. Based on these studies, most of the vandetanib metabolism was attributed to N-desmethylvandetanib/vandetanib-N-oxide to CYP3A4/FMO3. Recombinant CYP3A4 was most efficient to form N-desmethylvandetanib, while FMO1/FMO3 generated N-oxide. Cytochrome b₅ stimulated the CYP3A4-catalyzed formation of N-desmethylvandetanib, which is of great importance because CYP3A4 is not only most efficient in generating N-desmethylvandetanib, but also most significant due to its high expression in human liver. Molecular modeling indicated that binding of more than one molecule of vandetanib into the CYP3A4-active center can be responsible for the high efficiency of CYP3A4 N-demethylating vandetanib. Indeed, the CYP3A4-mediated reaction exhibits kinetics of positive cooperativity and this corresponded to the in silico model, where two vandetanib molecules were found in CYP3A4-active center.

Application of the Enzymatic Electrochemical Biosensors for Monitoring Non-Competitive Inhibition of Enzyme Activity by Heavy Metals

The inhibition effect of the selected heavy metals (Ag⁺, Cd²⁺, Cu²⁺, and Hg²⁺) on glucose oxidase (GOx) enzyme from Aspergillus niger (EC 1.1.3.4.) was studied using a new amperometric biosensor with an electrochemical transducer based on a glassy carbon electrode (GCE) covered with a thin layer of multi-wall carbon nanotubes (MWCNTs) incorporated with ruthenium(IV) oxide as a redox mediator. Direct adsorption of multi-wall carbon nanotubes (MWCNTs) and subsequent covering with Nafion^® layer was used for immobilization of Gox. The analytical figures of merit of the developed glucose (Glc) biosensor are sufficient for determination of Glc in body fluids in clinical analysis. From all tested heavy metals, mercury(II) has the highest inhibition effect. However, it is necessary to remember that cadmium and silver ions also significantly inhibit the catalytic activity of Gox. Therefore, the development of Gox biosensors for selective indirect determination of each heavy metal still represents a challenge in the field of bioelectroanalysis. It can be concluded that amperometric biosensors, differing in the utilized enzyme, could find their application in the toxicity studies of various poisons.

Bioavailability of mercury in contaminated soils assessed by the diffusive gradient in thin film technique in relation to uptake by Miscanthus × giganteus

We assessed the relationship between the diffusive gradient in thin film (DGT) technique using the new ion-exchange resin Ambersep GT74 and the uptake of mercury (Hg) by a model plant cultivated on metal-contaminated agricultural soils under greenhouse conditions. Based on the total Hg content, 0.37 to 1.17% of the Hg passed to the soil porewater from the solid phase, and 2.18 to 9.18% of the Hg is DGT-available. These results were confirmed by calculating the R value (the ratio of the concentrations of bioavailable Hg measured by DGT and soil solution), which illustrated the strong bonding of Hg to the solid phase of soil and its extremely low mobility. Only inorganic Hg²⁺ species were found in the metal-contaminated agricultural soils, as determined by a high-performance liquid chromatography-cold vapor atomic fluorescence spectrometry speciation analysis. The Hg was distributed in Miscanthus × giganteus organs in the following order for all sampling sites: roots (55-82%) >> leaves (8-27%) > stems (7-16%) > rhizomes (4-7%). Environ Toxicol Chem 2019;38:321-328. © 2018 SETAC.

Immobilization of ligninolytic enzymes from white-rot fungi in cross-linked aggregates

Ligninolytic enzymes from white-rot fungi are widely used in biotechnological processes. However, the application of these enzymes as free enzymes is limited due to their instability and lack of reusability. Enzyme stabilization is therefore a major challenge in biocatalytic process research, and immobilization methods are desirable. Using cross-linked enzyme aggregates (CLEAs) such as magnetic CLEAs, porous-CLEAs and combi-CLEAs is a promising technique for overcoming these issues. Cross-linking methods can stabilize and immobilize enzymes by interconnecting enzyme molecules via multiple bonds using cross-linking agents such as glutaraldehyde. The high catalyst density and microporous assembly of CLEAs guarantee high catalyst activity, which, together with their long shelf life, operational stability, and reusability, provide a cost-efficient alternative to matrix-assisted immobilization approaches. Here, we review current progress in ligninolytic enzyme immobilization and provide a comprehensive review of CLEAs. Moreover, we summarize the use of these CLEAs for biocatalysis processes, bioremediation such as dye decolourization, wastewater treatment or pharmaceutically active compound elimination.

[Identifying the Importance of MT-3 Expression for Neuroblastoma Cells]

BACKGROUND

Resistance of cancer cells to cytostatics is caused by a number of mechanisms that are often combined. These include reduced cell entry or increased efflux, increased DNA repair, defects of, apoptotic pathways, increased cytostatic degradation as well as elevated levels of intracellular thiols of glutathione and metallothioneins (MT). It has been reported that high concentrations of thiol groups in the cytoplasm bind platinum alkylation derivatives and chemorezistence is due to the transfer of platinum from the cytostatic to MT, which inactivates them. Because we have shown an increase in MT levels in resistant neuroblastoma (NB) lines, but not in sensitive lines after incubation with platinum cytostatics, we have considered MT-3 for NB cells in our previous studies.

METHOD

SiMa NB cell lines transfected with vector containing human MT-3 and GFP or GFP only (control). Expression Microarray Human Cancer 3711 ElectraSense medium density 4 × 2k array slides with 1,609 DNA probes (Custom Array, Bothell, WA, USA), MT-3 expression and most expressed genes validated by real-time polymerase chain reaction. Sensitivity to CDDP (cisplatin) - MTT assay, clonogenicity test, Western blott caspase cleavage and free oxygen radicals fluorescence microscopy after CellROX Deep Red Reagent staining. Levels of MT-3 mRNA in 23 samples of high-risk NB, normal human cortex and bovine adrenal glands were investigated by reverse transcription polymerase chain reaction.

RESULTS

Expression microarray showed downregulation 3 and overexpression of 19 genes in MT-3 transfected NB cells. Using gene ontology, over-expressed genes have been shown to drive senescence-induced oncogenes (CDKN2B and ANAPC5), and the genes of glutathione S-transferase M3, caspase 4 and DNAJB6 (chaperone neuronal proteins) were also expressed. We have demonstrated a reduced sensitivity of MT-3 transfected cells to CDDP (24h IC50 of 7.48 ± 0.97 and 19.81 ± 1.2 μg/ml), a higher number of colonies after incubation with CDDP, reduced caspase 3 after incubation with CDDP and lower free oxygen radicals after induction of CDDP. High-grade NB cells expressed MT-3 significantly more than non-tumoral adrenal cells but failed to show a clear relationship to disease course.

CONCLUSION

We have demonstrated the relationship between MT-3 and senescence-induced oncogene genes and some other genes relevant to cell fate (glutathione S-transferase M3, caspase 4 and DNAJB6) and a significant proportion of MT-3 on CDDP resistance. High levels of MT-3 in high-risk NB could be one of the causes of frequent relapses in this tumor.Key words: neuroblastoma - metallothionein 3 - chemoresistance The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.This work was supported by AZV CR grant 15- 28334A. Submitted: 17. 2. 2018Accepted: 16. 4. 2018.

Dimerization leads to changes in APP (amyloid precursor protein) trafficking mediated by LRP1 and SorLA

Proteolytic cleavage of the amyloid precursor protein (APP) by α-, β- and γ-secretases is a determining factor in Alzheimer's disease (AD). Imbalances in the activity of all three enzymes can result in alterations towards pathogenic Aβ production. Proteolysis of APP is strongly linked to its subcellular localization as the secretases involved are distributed in different cellular compartments. APP has been shown to dimerize in cis-orientation, affecting Aβ production. This might be explained by different substrate properties defined by the APP oligomerization state or alternatively by altered APP monomer/dimer localization. We investigated the latter hypothesis using two different APP dimerization systems in HeLa cells. Dimerization caused a decreased localization of APP to the Golgi and at the plasma membrane, whereas the levels in the ER and in endosomes were increased. Furthermore, we observed via live cell imaging and biochemical analyses that APP dimerization affects its interaction with LRP1 and SorLA, suggesting that APP dimerization modulates its interplay with sorting molecules and in turn its localization and processing. Thus, pharmacological approaches targeting APP oligomerization properties might open novel strategies for treatment of AD.

Cytochrome b5 plays a dual role in the reaction cycle of cytochrome P450 3A4 during oxidation of the anticancer drug ellipticine

Abstract

Ellipticine is an anticancer agent that forms covalent DNA adducts after enzymatic activation by cytochrome P450 (CYP) enzymes, mainly by CYP3A4. This process is one of the most important ellipticine DNA-damaging mechanisms for its antitumor action. Here, we investigated the efficiencies of human hepatic microsomes and human recombinant CYP3A4 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b₅ reductase and/or cytochrome b₅ in Supersomes™ to oxidize this drug. We also evaluated the effectiveness of coenzymes of two of the microsomal reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of NADH:cytochrome b₅ reductase, to mediate ellipticine oxidation in these enzyme systems. Using HPLC analysis we detected up to five ellipticine metabolites, which were formed by human hepatic microsomes and human CYP3A4 in the presence of NADPH or NADH. Among ellipticine metabolites, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyellipticine were formed by hepatic microsomes as the major metabolites, while 7-hydroxyellipticine and the ellipticine N²-oxide were the minor ones. Human CYP3A4 in Supersomes™ generated only three metabolic products, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyellipticine. Using the ³²P-postlabeling method two ellipticine-derived DNA adducts were generated by microsomes and the CYP3A4-Supersome system, both in the presence of NADPH and NADH. These adducts were derived from the reaction of 13-hydroxy- and 12-hydroxyellipticine with deoxyguanosine in DNA. In the presence of NADPH or NADH, cytochrome b₅ stimulated the CYP3A4-mediated oxidation of ellipticine, but the stimulation effect differed for individual ellipticine metabolites. This heme protein also stimulated the formation of both ellipticine-DNA adducts. The results demonstrate that cytochrome b₅ plays a dual role in the CYP3A4-catalyzed oxidation of ellipticine: (1) cytochrome b₅ mediates CYP3A4 catalytic activities by donating the first and second electron to this enzyme in its catalytic cycle, indicating that NADH:cytochrome b₅ reductase can substitute NADPH-dependent POR in this enzymatic reaction and (2) cytochrome b₅ can act as an allosteric modifier of the CYP3A4 oxygenase.

Graphical abstract

Clinical practice guidelines of the French Association for Supportive Care in Cancer and the French Society for Psycho-oncology: refusal of treatment by adults afflicted with cancer

PURPOSE

The study's purpose was to develop practical guidelines for assessment and management of refusal of treatment by adults afflicted with cancer.

METHODS

The French Association for Supportive Care in Cancer and the French Society for Psycho-oncology gathered a task force that applied a consensus methodology to draft guidelines studied predisposing situations, the diagnosis, regulatory aspects, and the management of refusal of treatment by adults afflicted with cancer.

RESULTS

We propose five guidelines: (1) be aware of the conditions/profiles of patients most often associated with refusal of treatment so as to adequately underpin the care and support measures; (2) understand the complexity of the process of refusal and knowing how to accurately identify the type and the modalities of the refused treatments; (3) apply a way to systematically analyze refusal, thereby promoting progression from a situation of disaccord toward a consensual decision; (4) devise procedures, according to the legal context, to address refusal of treatment that safeguards the stakeholders in situations of sustained disaccord; and (5) know the indications for ethical collective decision-making.

CONCLUSION

The quality of the relationship between patients and health professionals, and the communication between them are essential components involved in reaching a point of consent or refusal of treatment. A process of systematic analysis of refusal is recommended as the only way to ensure that all of the physiological, psychological, and contextual elements that are potentially involved are taken into account.

Trk Receptors and Neurotrophin Cross-Interactions: New Perspectives Toward Manipulating Therapeutic Side-Effects

Some therapeutic side-effects result from simultaneous activation of homolog receptors by the same ligand. Tropomyosin receptor kinases (TrkA, TrkB and TrkC) play a major role in the development and biology of neurons through neurotrophin signaling. The wide range of cross-interactions between Trk receptors and neurotrophins vary in selectivity, affinity and function. In this study, we discuss new perspectives to the manipulation of side-effects via a better understanding of the cross-interactions at the molecular level, derived by computational methods. Available crystal structures of Trk receptors and neurotrophins are a valuable resource for exploitation via molecular mechanics (MM) and dynamics (MD). The study of the energetics and dynamics of neurotrophins or neurotrophic peptides interacting with Trk receptors will provide insight to structural regions that may be candidates for drug targeting and signaling pathway selection.

Effect of inoculation with white-rot fungi and fungal consortium on the composting efficiency of municipal solid waste

An investigation was carried out on the effect of inoculation methods on the compost of an organic fraction of municipal solid waste. Three types of white-rot fungi (Phanerochaete chrysosporium, Trametes versicolor and Fomes fomentarius), and a consortium of these fungi, were used. The study assessed their influence on microbial enzymatic activities and the quality of the finished compost. It was found that the addition of white-rot fungi to municipal solid waste (after 37days of composting) could be a useful strategy for enhancing the properties of the final compost product. In comparison with the control sample (compost without inoculation), it accelerates degradation of solid waste as indicated by changes in C/N, electrical conductivity and pH. However, the effectiveness of waste degradation and compost maturation depends on the type of microorganism used for inoculation. The presence of inoculants, such as Trametes versicolor and Fomes fomentarius, led to a higher degrading ratio and a better degree of maturity. This resulted in an increase of enzymatic activities (especially dehydrogenase and protease) and a germination index in comparison with inoculation using Phanerochaete chrysosporium or a consortium of fungi.

[Glycine-N-methyltransferase and Malignant Diseases of the Prostate]

BACKGROUND

Prostate cancer (PC) constitutes a heterogeneous group of diseases with high prevalence rates that are still increasing, particularly in western countries. Since 1980, prostate specific antigen (PSA) and other diagnostic approaches have been used for PC screening; however, some of these approaches are often deemed painful and cause invasive damage of tissue. Therefore, molecular approaches to PC diagnosis are attracting increasing attention, potentially providing patients with less stressful situations and providing better diagnoses and even prognostic information. Recent metabolomic and genomic studies have suggested that biomolecules can be used as diagnostic or prognostic markers or as targets for the development of novel therapeutic modalities. One of these molecules is glycine-N-methyltransferase (GNMT), an enzyme that plays a pivotal role in the biochemical conversion of glycine to sarcosine. The link between this molecule (encoded by homonymous gene - GNMT) and PC has been confirmed at several levels, and thus GNMT can be considered a promising target for the development of advanced diagnostic and/or prognostic approaches.

AIM

The aim of this study was to analyse the physiological role of GNMT and to examine in greater detail its connection with PC at different levels, including gene structure, gene expression, and metabolism, in which GNMT plays an important role, not only in controlling the methylation status of cells, but also the metabolism of folic acid and methionine. Last but not least, we discuss the importance of cellular methylation processes and the link between their aberrations and PC development.Key words: glycine - folic acid - metabolism - methylation - sarcosineThis work was supported by GA CR 16-18917S, League against Cancer Prague (project 2022015) and Czech Ministry of Health - RVO, UH Motol 00064203.The authors declare they have no potential confl icts of interest concerning drugs, products, or services used in the study.The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 9. 2. 2016Accepted: 20. 3. 2016.

Metallothionein modulation in relation to cadmium bioaccumulation and age-dependent sensitivity of Chironomus riparius larvae

The goal of this study was to contribute to understanding of the mechanisms behind sensitivity differences between early and late instar larvae of Chironomus riparius and to address the influence of the differences in standard testing approaches on the toxicity evaluation. A 10-day contact sediment toxicity test was carried out to assess sensitivity to cadmium exposure in relation to different age and laboratory culture line origin of test organisms. Chironomid larvae of early (OECD 218 method) and late instar (US-EPA600/R-99/064 method) differed substantially in sensitivity of traditional endpoints (OECD: LOEC 50 and 10 μg Cd/g dry weight (dw); US-EPA: LOEC > 1000 and 100 μg Cd/g dw for survival and growth, respectively). Bioaccumulated cadmium and metallothioneins (MTs) concentrations were analyzed to investigate the role of MTs in reduced sensitivity to cadmium in late instar larvae. Metallothioneins were induced after treatment to greater Cd concentrations, but their levels in relation to cadmium body burdens did not fully explain low sensitivity of late instars to cadmium, which indicates some other effective way of detoxification in late instars. This study brings new information related to the role of MTs in age-dependent toxicant sensitivity and discusses the implications of divergence in data generated by chironomid sediment toxicity tests by standardized methods using different instars.

Induced expression of microsomal cytochrome b5 determined at mRNA and protein levels in rats exposed to ellipticine, benzo[a]pyrene, and 1-phenylazo-2-naphthol (Sudan I)

ABSTRACT

The microsomal protein cytochrome b5 , which is located in the membrane of the endoplasmic reticulum, has been shown to modulate many reactions catalyzed by cytochrome P450 (CYP) enzymes. We investigated the influence of exposure to the anticancer drug ellipticine and to two environmental carcinogens, benzo[a]pyrene (BaP) and 1-phenylazo-2-naphthol (Sudan I), on the expression of cytochrome b5 in livers of rats, both at the mRNA and protein levels. We also studied the effects of these compounds on their own metabolism and the formation of DNA adducts generated by their activation metabolite(s) in vitro. The relative amounts of cytochrome b5 mRNA, measured by real-time polymerase chain reaction analysis, were induced by the test compounds up to 11.7-fold in rat livers. Western blotting using antibodies raised against cytochrome b5 showed that protein expression was induced by up to sevenfold in livers of treated rats. Microsomes isolated from livers of exposed rats catalyzed the oxidation of ellipticine, BaP, and Sudan I and the formation of DNA adducts generated by their reactive metabolite(s) more effectively than hepatic microsomes isolated from control rats. All test compounds are known to induce CYP1A1. This induction is one of the reasons responsible for increased oxidation of these xenobiotics by microsomes. However, induction of cytochrome b5 can also contribute to their enhanced metabolism.

GRAPHICAL ABSTRACT

[Modern Nanomedicine in Treatment of Lung Carcinomas]

BACKGROUNDS

Despite the fast development of new effective cytostatics and targeted therapy, the treatment efficiency of lung cancer is still insufficient. The systemic administration of drugs results in a decrease in drug concentrations in tumor site, particularly due to specific extracellular environment in lungs. Nanotransporters could serve as a platform, protecting a drug against these undesired effects, which may enhance its therapeutic index and reduce side effects of a drug. Moreover, nanotechnologies possess the potential to improve the diagnostics of lung cancer, and thus increase a survival rate of oncologic patients.

AIM

The presented study is aimed to demonstrate the possibilities provided by nanotechnologies in the field of treatment and diagnostic of lung cancers and discuss the obstacles, which complicate a translation into clinical practice.

Melatonin Regulates Oxidative Stress Initiated by Freund’s Complete Adjuvant

Melatonin is a hormone with strong antioxidant properties. In this experiment, Freund’s complete adjuvant was used as a stressogenic substance given to laboratory outbred mice, whereas melatonin was investigated as a protectant against the stressogenic effect. Levels of low molecular weight antioxidants, thiobarbituric acid reactive substances, and tumor necrosis factor α and activity of glutathione reductase were determined in blood from the animals. Surprisingly, melatonin was not involved in direct regulation of antioxidants, thiobarbituric acid reactive substances and tumor necrosis factor α. On the other hand, melatonin regulated glutathione reductase activity. We can conclude on regulation of metabolism caused by melatonin in the model. The effect was more important than the expected regulation of immunity and basal oxidative homeostasis.

Jacks of metal/metalloid chelation trade in plants-an overview

Varied environmental compartments including soils are being contaminated by a myriad toxic metal(loid)s (hereafter termed as "metal/s") mainly through anthropogenic activities. These metals may contaminate food chain and bring irreparable consequences in human. Plant-based approach (phytoremediation) stands second to none among bioremediation technologies meant for sustainable cleanup of soils/sites with metal-contamination. In turn, the capacity of plants to tolerate potential consequences caused by the extracted/accumulated metals decides the effectiveness and success of phytoremediation system. Chelation is among the potential mechanisms that largely govern metal-tolerance in plant cells by maintaining low concentrations of free metals in cytoplasm. Metal-chelation can be performed by compounds of both thiol origin (such as GSH, glutathione; PCs, phytochelatins; MTs, metallothioneins) and non-thiol origin (such as histidine, nicotianamine, organic acids). This paper presents an appraisal of recent reports on both thiol and non-thiol compounds in an effort to shed light on the significance of these compounds in plant-metal tolerance, as well as to provide scientific clues for the advancement of metal-phytoextraction strategies.

Prostate cancer, miRNAs, metallothioneins and resistance to cytostatic drugs

MicroRNAs (miRNAs) translationally repressing their target messenger RNAs due to their gene-regulatory functions play an important but not unexpected role in a tumour development. More surprising are the findings that levels of various miRNAs are well correlated with presence of specific tumours and formation of metastases. Moreover, these small regulatory molecules play a role in the resistance of cancer cells to commonly used anti-cancer drugs, such as cisplatin, anthracyclines, and taxanes. In that respect, miRNAs become very attractive target for potential therapeutic interventions. Improvements in the sensitivity of miRNAs detection techniques led to discovery of circulating miRNAs which became very attractive non-invasive biomarker of cancer with a substantial predictive value. In this review, the authors focus on i) oncogenic and anti-tumour acting miRNAs, ii) function of miRNAs in tumour progression, iii) possible role of miRNAs in resistance to anticancer drugs, and iv) diagnostic potential of miRNAs for identification of cancer from circulating miRNAs with special emphasis on prostate cancer. Moreover, relationship between miRNAs and expression of metallothionein is discussed as a possible explanation of resistance against platinum based drugs.

[Modern imaging techniques for anthracycline cytostatics - review of the literature]

Anthracycline cytostatics can be observed at the level of organelles, cells and whole organisms due to their fluorescent properties. Imaging techniques based on detection of fluorescence can be used not only for observation of drug interaction with tumor cells, but also for targeting therapy of tumors with nanoparticles containing anthracycline cytostatics. Doxorubicin and daunorubicin, enclosed in liposomes, as representatives of nanoparticles suitable for targeted therapy, are used in clinical practice. The main advantage of liposomal drugs is to reduce the side effects due to differences in pharmacokinetics and distribution of the drug in the body. Due to the fact that all biological mechanisms of action of anthracycline drugs are not still fully understood, modern imaging techniques offer tool for in vivo studies of these mechanisms.

Insight to physiology and pathology of zinc(II) ions and their actions in breast and prostate carcinoma

Zinc(II) ions contribute to a number of biological processes e.g. DNA synthesis, gene expression, enzymatic catalysis, neurotransmission, and apoptosis. Zinc(II) dysregulation, deficiency and over-supply are connected with various diseases, particularly cancer. 98 % of human body zinc(II) is localized in the intracellular compartment, where zinc(II) is bound with low affinity to metallothionein (MT). Zinc transporters ZIP and ZnT maintain transmembrane transport from/to cells or organelles. Imbalance of their regulation is described in cancers, particularly prostate (down-regulated zinc transporters ZIP1, 2, 3 and ZnT-2) and breast, notably its high-risk variant (up-regulated ZIP6, 7, 10). As a result, intracellular and even blood plasma zinc(II) levels are altered. MT protects cells against oxidative stress, because it cooperates with reduced glutathione (GSH). Recent studies indicate elevated serum level of MT in a number of malignancies, among others in breast, and prostate. MT together with zinc(II) affect apoptosis and proliferation, thus together with its antioxidative effects it may affect cancer. To date, only little is known about the influence of zinc(II) and MT on cancer, while these compounds may play an important role in pathogenesis. This review concludes current data regarding the impact of zinc(II) on the pathogenesis of breast and prostate cancers with potential outlines of new, targeted therapy and prevention. Moreover, blood plasma zinc(II) and MT levels and dietary zinc(II) intake are discussed in relation to breast and prostate cancer risk.

Matrix metalloproteinases

Matrix metalloproteinases (MMPs), also known as matrixins, belong to a group of zinc-dependent proteins, which are thought to play a central role in the breakdown of extracellular matrix. Collagen, elastin, gelatin and casein are major components cleaved by MMPs. The breakdown of these components is essential for many physiological processes such as embryonic development, morphogenesis, reproduction, and tissue resorption and remodelling. MMPs also participate in pathological processes such as arthritis, cancer, cardiovascular and neurological diseases. This review summarizes current knowledge regarding these proteins, their participation in physiological and pathophysiological roles, their involvement in activation and inhibition, and their interactions with other metal-binding proteins including metallothioneins.

Forage as a primary source of mycotoxins in animal diets

The issue of moulds and, thus, contamination with mycotoxins is very topical, particularly in connexion with forages from grass stands used at the end of the growing season. Deoxynivalenol (DON), zearalenone (ZEA), fumonisins (FUM) and aflatoxins (AFL) are among the most common mycotoxins. The aim of the paper was to determine concentrations of mycotoxins in selected grasses (Lolium perenne, Festulolium pabulare, Festulolium braunii) and their mixtures with Festuca rubra an/or Poa pratensis during the growing season as a marker of grass safety, which was assessed according to content of the aforementioned mycotoxins. During the growing season grass forage was contaminated with mycotoxins, most of all by DON and ZEA. The contents of AFL and FUM were zero or below the limit of quantification. Moreover, the level of the occurrence of mould was quantified as ergosterol content, which was higher at the specific date of cut. All results were statistically processed and significant changes were discussed.

Clinical importance of matrix metalloproteinases

This review gives a brief summary on clinical applications of MMPs and their determination. Primarily, the activity of MMPs in cancer formation, development and metastasis is discussed. Further, survey on methods including fluorimetric methods, zymographies, Western-blotting, immunocapture assay, enzyme-linked immunosorbent assay, immunocytochemistry and immunohistochemistry, phage display, multiple-enzyme/multiple-reagent system, activity profiling, chronopotentiometric stripping analysis and imaging methods for detection and determination of MMPs follows (Fig. 3, Ref. 100).

Metallothionein--a promising tool for cancer diagnostics

The latest research outcomes indicate that metallothionein (MT) levels in peripheral blood and serum from cancer patients can provide many interesting information about type or clinical stage of the disease, or response to therapy. MT plays a key role in transport of essential heavy metals, detoxification of toxic metals and protection of cells against oxidation stress. Serum MT levels of cancer patients are three times higher than control patients (0.5 microM). The elevated MT levels in cancer cells are probably related to their increased proliferation and protection against apoptosis. Automated electrochemical detection of MT allows its serial analysis in a very small volume with excellent sensitivity, reliability and reproducibility and therefore it can be considered as a new tool for cancer diagnosis (Fig. 4, Ref. 55). Full Text (Free, PDF) www.bmj.sk.

[Naphthoquinones and their pharmacological properties]

Naphthoquinones are wide-spread phenolic compounds in nature. They are products of bacterial and fungal as well as high-plants secondary metabolism. Juglone, lawsone, and plumbagin are the most widespread compounds. Naphthoquinones display very significant pharmacological properties--they are cytotoxic, they have significant antibacterial, antifungal, antiviral, insecticidal, anti-inflammatory, and antipyretic properties. Pharmacological effects to cardiovascular and reproductive systems have been demonstrated too. The mechanism of their effect is highly large and complex--they bind to DNA and inhibit the processes of replication, interact with numerous proteins (enzymes) and disturb cell and mitochondrial membranes, interfere with electrons of the respiratory chain on mitochondrial membranes. Plants with naphthoquinone content are widely used in China and the countries of South America, where they are applied to malignant and parasitic diseases treatment.

The roles of magnetic resonance and endoscopic retrograde cholangiopancreatography (MRCP and ERCP) in the diagnosis of patients with suspected sclerosing cholangitis: a cost-effectiveness analysis

BACKGROUND AND STUDY AIMS

The optimal approach for diagnosing sclerosing cholangitis remains unclear in the face of competing imaging technologies. We aimed to determine the most cost-effective strategy.

PATIENTS AND METHODS

A decision model compared three approaches in the work-up of patients with suspected sclerosing cholangitis; all included an initial test, with, if unsuccessful, performance of a second cholangiographic method. They were magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERCP), termed "MRCP_ERCP", ERCP and MRCP ("ERCP_MRCP"), or ERCP and a repeat ERCP ("ERCP_ERCP"). The implications of true and false positive and negative results with regard to costs and procedural complications were considered, including that of a liver biopsy, if indicated as a result of a negative work-up in the face of persistent clinical suspicion. The unit of effectiveness adopted was that of a correct diagnosis. Probability assumptions were derived from published literature, while cost estimates were derived from time-motion microanalyses or a national database, and expressed in Canadian dollars at 2004 values. Sensitivity analyses, including clinically relevant threshold analyses, were carried out.

RESULTS

The average cost-effectiveness ratios were $414 for MRCP_ERCP, $1101 for ERCP_MRCP and $1123 for ERCP_ERCP, per correct diagnosis. The ERCP_MRCP strategy was dominated (more expensive and less effective) by MRCP_ERCP, while ERCP_ERCP was more effective and more costly than MRCP_ERCP, at $289,292 per additional correct diagnosis. Sensitivity and threshold analyses confirmed the robustness of these findings.

CONCLUSIONS

Based on the model assumptions, a strategy of initial MRCP, followed, if negative, by ERCP is currently the most cost-effective approach to the work-up of patients with suspected sclerosing cholangitis.