Identifying nanodescriptors to predict the toxicity of nanomaterials: a case study on titanium dioxide

2021 ◽  
Vol 8 (2) ◽  
pp. 580-590
Author(s):  
Sivakumar Murugadoss ◽  
Nilakash Das ◽  
Lode Godderis ◽  
Jan Mast ◽  
Peter H. Hoet ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Biological Activity ◽  
Safety Assessment ◽  
Experimental Conditions

Use of non-standardized in vitro experimental conditions in TiO2 NM safety assessment can lead to misleading results in establishing TiO2 properties–biological activity relationships.

Validation of Reference Genes for RT-qPCR in Marine Bivalve Ecotoxicology: Systematic Review and Case Study

2016 ◽  
Author(s):  
Moritz Volland ◽  
Julián Blasco ◽  
Miriam Hampel
Keyword(s):  
Reference Gene ◽  
Reference Genes ◽  
Good Practice ◽  
Optimal Number ◽  
Suitable Reference Gene ◽  
Marine Bivalve ◽  
Mrna Levels ◽  
Experimental Conditions

AbstractReverse transcription real-time quantitative PCR (RT-qPCR) is the predominant method of choice for the quantification of mRNA transcripts of a selected gene of interest. Here reference genes are commonly used to normalize non-biological variation in mRNA levels and their appropriate selection is therefore essential for the accurate interpretation the collected data. In recent years the use of multiple validated references genes has been shown to substantially increase the robustness of the normalization. It is therefore considered good practice to experimentally validate putative reference genes under specific experimental conditions, determine the optimal number of reference genes to be employed, and report the method or methods used.Under this premise, we assessed the current state of reference gene base normalization in RT-qPCR bivalve ecotoxicology studies (post 2011), employing a systematic quantitative literature review. A total of 52 papers published met our criteria and were analysed for the gene or genes used, whether they employed multiple reference genes, as well as the validation method employed. In addition we performed a case study using primary hemocytes from the marine bivalve Ruditapes philippinarum after in vitro copper exposure. Herein we further critically discuss methods for reference gene validation, including the established algorithms geNorm, NormFinder and BestKeeper, as well as the popular online tool RefFinder.We identified that RT-qPCR normalization in bivalve ecotoxicology studies is largely performed using single reference genes, while less than 40% of the studies attempted to experimentally validate the expression stability of the reference genes used. 18s rRNA and β-Actin were the most popular genes, yet their un-validated use did introduce artefactual variance that altered the interpretation of the resulting data, while the use of appropriately validated reference genes did substantially improve normalization. Our findings further suggest that combining the results from multiple individual algorithms and calculating the overall best-ranked gene, as e.g. computed by the RefFinder tool, does not by default lead to the identification of the most suitable reference gene or combination of reference genes.

Incorporation of human relevant metabolism into fit-for-purpose in vitro assays for safety assessment: Case study with bioactivated mutagens

2017 ◽  
Vol 280 ◽  
pp. S273
Author(s):  
Rebecca Clewell ◽  
Martin Phillips ◽  
Katie Dunnick ◽  
Pergentino Balbuena ◽  
Miyoung Yoon
Keyword(s):  
Safety Assessment ◽  
In Vitro Assays ◽  
Fit For Purpose

scholarly journals Innovative Delivery of Cu(II) Ions by a Nanostructured Hydroxyapatite: Potential Application in Planta to Enhance the Sustainable Control of Plasmopara viticola

2019 ◽  
Vol 109 (5) ◽  
pp. 748-759
Author(s):  
Enrico Battiston ◽  
Livio Antonielli ◽  
Stefano Di Marco ◽  
Florence Fontaine ◽  
Laura Mugnai
Keyword(s):  
Biological Activity ◽  
Downy Mildew ◽  
Effective Means ◽  
Plasmopara Viticola ◽  
In Planta ◽  
Experimental Conditions ◽  
Synthetic Hydroxyapatite ◽  
Serious Disease ◽  
Dose Variation

Downy mildew caused by Plasmopara viticola is probably the most serious disease affecting grapevine (Vitis vinifera), and it is capable of causing consistent yield losses. In organic viticulture, the only acceptable and effective means to control the disease is by applications of copper-based fungicides. However, the use of copper in agriculture is expected to be further restricted by European countries because of its critical ecotoxicological and phytotoxicological profile. Research on ways to reduce the effective amounts of copper by developing innovative formulations as well as optimization of the distribution and persistence of copper-based pesticides for downy mildew control seems to be a promising approach. This research investigated the delivery properties of biomimetic synthetic hydroxyapatite (HA) to enhance the biological activity of Cu(II) ions. To this aim, four Cu(II) compounds were formulated with the innovative HA component and applied in an in vitro antifungal assay against Botrytis cinerea, a common grapevine pathogen suitable for in vitro activity tests, and finally, in in planta efficacy assays against P. viticola under greenhouse conditions. The in vitro results highlighted a different inhibition activity for each Cu(II) compound and indicated a different interaction between the cupric compounds and HA, potentially related to different delivery mechanisms of Cu(II) from HA. Under greenhouse conditions, additional findings on the biological activity of the applied formulations were gained, especially on the efficacy of various concentrations of HA in the formulations, the influence of dose variation of the formulation and the treatment efficiency, and the persistence under rain-washing effect. This study revealed promising findings on the formulation based on the HA particles and the soluble Cu(II) compound, which resulted in reduced disease severity and incidence in all of the experimental conditions, including the lower Cu(II) dosage and the rain-washing effect. This suggests that coformulation of the three insoluble Cu(II) compounds with HA might significantly enhance the adsorption and release of Cu(II) ions by HA particles.

Observations of Frozen-Hydrated Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 504-505
Author(s):  
D. Chrétien ◽  
D. Job ◽  
R.H. Wade
Keyword(s):  
Fourier Transforms ◽  
Structural Complexity ◽  
Image Contrast ◽  
Phase Behaviour ◽  
Experimental Conditions ◽  
Thin Sections ◽  
Surface Lattice ◽  
Cilia And Flagella ◽  
Outstanding Question

Microtubules are filamentary structures found in the cytoplasm of eukaryotic cells, where, together with actin and intermediate filaments, they form the components of the cytoskeleton. They have many functions and show various levels of structural complexity as witnessed by the singlet, doublet and triplet structures involved in the architecture of centrioles, basal bodies, cilia and flagella. The accepted microtubule model consists of a 25 nm diameter hollow tube with a wall made up of 13 paraxial protofilaments (pf). Each pf is a string of aligned tubulin dimers. Some results have suggested that the pfs follow a superhelix. To understand how microtubules function in the cell an accurate model of the surface lattice is one of the requirements. For example the 9x2 architecture of the axoneme will depend on the organisation of its component microtubules. We should also note that microtubules with different numbers of pfs have been observed in thin sections of cellular and of in-vitro material. An outstanding question is how does the surface lattice adjust to these different pf numbers?We have been using cryo-electron microscopy of frozen-hydrated samples to study in-vitro assembled microtubules. The experimental conditions are described in detail in this reference. The results obtained in conjunction with thin sections of similar specimens and with axoneme outer doublet fragments have already allowed us to characterise the image contrast of 13, 14 and 15 pf microtubules on the basis of the measured image widths, of the the image contrast symmetry and of the amplitude and phase behaviour along the equator in the computed Fourier transforms. The contrast variations along individual microtubule images can be interpreted in terms of the geometry of the microtubule surface lattice. We can extend these results and make some reasonable predictions about the probable surface lattices in the case of other pf numbers, see Table 1. Figure 1 shows observed images with which these predictions can be compared.

Superoxide, Xanthine Oxidase and Platelet Reactions: Further Studies on Mechanisms by which Oxidants Influence Platelets

1981 ◽  
Vol 45 (03) ◽  
pp. 290-293 ◽  
Author(s):  
Peter H Levine ◽  
Danielle G Sladdin ◽  
Norman I Krinsky
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Direct Effect ◽  
Platelet Function ◽  
Experimental Conditions ◽  
Release Reaction

SummaryIn the course of studying the effects on platelets of the oxidant species superoxide (O- 2), Of was generated by the interaction of xanthine oxidase plus xanthine. Surprisingly, gel-filtered platelets, when exposed to xanthine oxidase in the absence of xanthine substrate, were found to generate superoxide (O- 2), as determined by the reduction of added cytochrome c and by the inhibition of this reduction in the presence of superoxide dismutase.In addition to generating Of, the xanthine oxidase-treated platelets display both aggregation and evidence of the release reaction. This xanthine oxidase induced aggreagtion is not inhibited by the addition of either superoxide dismutase or cytochrome c, suggesting that it is due to either a further metabolite of O- 2, or that O- 2 itself exerts no important direct effect on platelet function under these experimental conditions. The ability of Of to modulate platelet reactions in vivo or in vitro remains in doubt, and xanthine oxidase is an unsuitable source of O- 2 in platelet studies because of its own effects on platelets.

Desmopressin (DDAVP) Enhances Platelet Adhesion to the Extracellular Matrix of Cultured Human Endothelial Cells through Increased Expression of Tissue Factor

1997 ◽  
Vol 77 (05) ◽  
pp. 0975-0980 ◽  
Author(s):  
Angel Gálvez ◽  
Goretti Gómez-Ortiz ◽  
Maribel Díaz-Ricart ◽  
Ginés Escolar ◽  
Rogelio González-Sarmiento ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Tissue Factor ◽  
Platelet Adhesion ◽  
Umbilical Vein ◽  
Procoagulant Activity ◽  
Experimental Conditions ◽  
Chromogenic Assay

SummaryThe effect of desmopressin (DDAVP) on thrombogenicity, expression of tissue factor and procoagulant activity (PCA) of extracellular matrix (ECM) generated by human umbilical vein endothelial cells cultures (HUVEC), was studied under different experimental conditions. HUVEC were incubated with DDAVP (1, 5 and 30 ng/ml) and then detached from their ECM. The reactivity towards platelets of this ECM was tested in a perfusion system. Coverslips covered with DD A VP-treated ECMs were inserted in a parallel-plate chamber and exposed to normal blood anticoagulated with low molecular weight heparin (Fragmin®, 20 U/ml). Perfusions were run for 5 min at a shear rate of 800 s1. Deposition of platelets on ECMs was significantly increased with respect to control ECMs when DDAVP was used at 5 and 30 ng/ml (p <0.05 and p <0.01 respectively). The increase in platelet deposition was prevented by incubation of ECMs with an antibody against human tissue factor prior to perfusion. Immunofluorescence studies positively detected tissue factor antigen on DDAVP derived ECMs. A chromogenic assay performed under standardized conditions revealed a statistically significant increase in the procoagulant activity of the ECMs produced by ECs incubated with 30 ng/ml DDAVP (p <0.01 vs. control samples). Northern blot analysis revealed increased levels of tissue factor mRNA in extracts from ECs exposed to DDAVP. Our data indicate that DDAVP in vitro enhances platelet adhesion to the ECMs through increased expression of tissue factor. A similar increase in the expression of tissue factor might contribute to the in vivo hemostatic effect of DDAVP.

COMPARATIVE STUDIES OF THE POTENTIATION OF CORTICOTROPHIN ACTIVITY BY SEVERAL INACTIVE DERIVATIVES

1963 ◽  
Vol 42 (2) ◽  
pp. 209-213 ◽  
Author(s):  
Arthur I. Cohen ◽  
Edward H. Frieden
Keyword(s):  
Biological Activity ◽  
Comparative Studies ◽  
Free Amino ◽  
Hormonal Activity ◽  
Amino Groups

ABSTRACT A number of corticotrophin analogues have been prepared, some of which potentiate the biological activity of the untreated hormone in vitro. The free amino groups of corticotrophin appear to be essential not only for hormonal activity, but also for the interaction of the analogues with the tissue corticotrophin inactivating system which is assumed to account for the potentiating effect.

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