Toxicity of methylmercury (MeHg) to wildlife and humans results from its binding to cysteine residues of proteins, forming MeHg-cysteinate (MeHgCys) complexes that hinder biological functions. ...MeHgCys complexes can be detoxified in vivo, yet how this occurs is unknown. We report that MeHgCys complexes are transformed into selenocysteinate Hg(Sec)4 complexes in multiple animals from two phyla (a waterbird, freshwater fish, and earthworms) sampled in different geographical areas and contaminated by different Hg sources. In addition, high energy-resolution X-ray absorption spectroscopy (HR-XANES) and chromatography-inductively coupled plasma mass spectrometry of the waterbird liver support the binding of Hg(Sec)4 to selenoprotein P and biomineralization of Hg(Sec)4 to chemically inert nanoparticulate mercury selenide (HgSe). The results provide a foundation for understanding mercury detoxification in higher organisms and suggest that the identified MeHgCys to Hg(Sec)4 demethylation pathway is common in nature.
BACKGROUND AND PURPOSE β‐Adrenoceptors are expressed in human and experimental animal breast cancer cells. However, the effect of the agonists and antagonists reported on cell proliferation and ...tumour growth was paradoxical, precluding their utilization as possible adjuvant therapy, mainly in the cases of refractory tumours.
EXPERIMENTAL APPROACH β‐Adrenoceptor expression was analysed by immunofluorescence and RT‐PCR. Cell proliferation was assessed by 3H‐thymidine incorporation, tumour growth by measuring with a calliper and ERK 1/2 phosphorylation by Western blotting.
KEY RESULTS β2‐Adrenoceptor expression was confirmed in the mouse and human cells tested. Cell proliferation was increased by adrenaline (by α2‐adrenoceptor action) and decreased in every tested cell line by the β‐adrenoceptor agonist isoprenaline and the β2‐adrenoceptor agonist salbutamol. Isoprenaline and salbutamol reduced tumour growth in every tumour tested (mouse C4‐HD and CC4‐3‐HI and human IBH‐4, IBH‐6 and MDA‐MB‐231 cell lines growing as xenografts in nude mice). These effects were reversed by the β‐adrenoceptor antagonist propranolol. The α2‐adrenoceptor antagonist rauwolscine and the β2‐adrenoceptor agonist salbutamol were equally effective in diminishing tumour growth. ERK 1/2 activation analysed in IBH‐4 tumours correlated with tumour growth, with the β‐adrenoceptor agonists decreasing its activation. Inhibition of ERK 1/2 phosphorylation in vitro was mainly mediated by the PKA pathway.
CONCLUSIONS AND IMPLICATIONS In our experimental models, the β‐adrenoceptor agonists inhibited breast cancer cell proliferation and tumour growth, probably mediated by inhibition of ERK 1/2 phosphorylation. The β‐adrenoceptor agonists were as effective as the α2‐adrenoceptor antagonist rauwolscine, providing possible novel adjuvant treatments for breast cancer.
This work reports on the development of a 3D microfluidic paper-based device (3D mu PAD) for glucose detection using organic-inorganic hybrid nanoflower technology to immobilize the bi-enzymatic ...system (glucose oxidase and horseradish peroxidase). The system is based on nanoflowerssupported on cellulose paper (the microreactor zone) coupled to 3,3',5,5'-tetramethylbenzidine (TMB) as the colorimetric probe in the detection zone. We used a digital camera for the quantitative analysis of glucose with the S coordinate of the HSV color space as the analytical parameter. Under optimal operational conditions, linearity was observed for glucose concentrations up to 300 mu M, with a detection limit of 15.6 mu M. The biosensor is reusable and remains stable for 75 days in conventional storage conditions.
Two colorimetric nanostructured sensor phases (Color-NSPs) for the determination of low concentrations of acid vapors in the atmosphere of paper storage rooms have been designed and characterized. ...The acid vapor determination is based on the color change that occurs in polyaniline (PANI) in the presence of acids when it goes from its emeraldine base form (blue) to its emeraldine salt form (green). To synthesize the Color-NSPs, two methods have been used, a one-step method performed by grafting polyaniline onto a cellulose membrane (Cellu-PANI) and a two-step method in which in the first step, polyaniline is grafted onto the surface of polymeric nanoparticles (NPs-PANI), and in a second step, NPs-PANI are immobilized into the pores of a nylon membrane (Nylon-NPs PANI). The response of the sensors versus acid vapor was measured by color coordinates with a photographic camera. A linear response range from 1 ppmv to 7 ppmv was found for both sensors, and the detection limits were 0.95 ppmv (1.2 % RSD) and 0.40 ppmv (0.8 % RSD) for Cellu-PANI and Nylon-NPs PANI, respectively. In addition, both sensors showed complete reversibility and a short exposition time (5 min). The potential applicability of the Color-NSPs in the control of the exposure of paper heritage collections to outdoor- and indoor-generated gaseous pollutants was demonstrated by determining acid vapors in museums. The method was validated with an external reference method; the paired test was applied, and
p-
values greater than 5% were obtained, indicating an excellent correlation and showing that the Color-NSPs reported are simple, fast, and an economical alternative to control and protect cultural heritage materials in indoor environments.
Graphical Abstract
Formaldehyde is a common contaminant in occupational and environmental atmospheres, prolonged exposure leads to health risks, and its determination is necessary to protect health. There is a great ...demand for portable, rapid, and sensitive methods that can be used in resource-limited settings. In this respect, a colorimetric sensor has been developed based on the colour change from pink to purple of co-immobilized chromotropic acid and 4-aminoazobenzene in hydroxypropyl methylcellulose when it is exposed to different concentrations of formaldehyde. The concentration of formaldehyde in the gas phase was quantified by measuring the change of the appropriate colour coordinates in response to the concentration of formaldehyde. A calibration curve was obtained for formaldehyde, with a useful concentration range from 0.08 to 0.6 ppmv. The detection limit was 0.016 ppmv, which is lower than the maximum exposure concentrations recommended by both the World Health Organization (WHO) and the Occupational Safety and Health Administration (OSHA). The optical sensor was found to have good reproducibility, with a relative standard deviation of 2.3 and 1.7% at 0.08 and 0.25 ppmv, respectively. The sensor can operate at room temperature and environmental humidity, 25 °C, and 50% RH, respectively. In addition, a study of interferents (acetaldehyde, toluene, methanol, ethyl acetate, acetone, acetic acid, carbon dioxide and ammonia) showed high selectivity for formaldehyde, which indicates that this membrane is a simple, fast, and economical alternative for quantifying the concentration of formaldehyde in different environments.
One of the main limiting factors in optical sensing arrays is the reproducibility in the preparation, typically by spin coating and drop casting techniques, which produce membranes that are not fully ...homogeneous. In this paper, we increase the discriminatory power of colorimetric arrays by increasing the reproducibility in the preparation by inkjet printing and measuring the color from the image of the array acquired by a digital camera, using the H coordinate of the HSV color space as the analytical parameter, which produces robust and precise measurements. A disposable 31 mm × 19 mm nylon membrane with 35 sensing areas with 7 commercial chromogenic reagents makes it possible to identify 13 metal ions and to determine mixtures with up to 5 ions using a two-stage neural network approach with higher accuracy than with previous approaches.
The effect of α-Al2O3 nanoparticles (up to 5 wt.%) on the physical, mechanical, and thermal properties, as well as on the microstructural evolution of a dense magnesia refractory is studied. ...Sintering temperatures at 1300, 1500, and 1600 °C are used. The physical properties of interest were bulk density and apparent porosity, which were evaluated by the Archimedes method. Thermal properties were examined by differential scanning calorimetry. The mechanical behavior was studied by cold crushing strength and microhardness tests. Finally, the microstructure and mineralogical qualitative characteristics were studied by scanning electron microscopy and X-ray diffraction, respectively. Increasing the sintering temperature resulted in improved density and reduced apparent porosity. However, as the α-Al2O3 nanoparticle content increased, the density and microhardness decreased. Microstructural observations showed that the presence of α-Al2O3 nanoparticles in the magnesia matrix induced the magnesium-aluminate spinel formation (MgAl2O4), which improved the mechanical resistance most significantly at 1500 °C.
It is a widely held belief that the sole effect of muscle on bone is through mechanical loading. However, as the two tissues are intimately associated, we hypothesized that muscle myokines may have ...positive effects on bone. We found that factors produced by muscle will protect osteocytes from undergoing cell death induced by dexamethasone (dex), a glucocorticoid known to induce osteocyte apoptosis thereby compromising their capacity to regulate bone remodeling. Both the trypan blue exclusion assay for cell death and nuclear fragmentation assay for apoptosis were used. MLO-Y4 osteocytes, primary osteocytes, and MC3T3 osteoblastic cells were protected against dex-induced apoptosis by C2C12 myotube conditioned media (MT-CM) or by CM from ex vivo electrically stimulated, intact extensor digitorum longus (EDL) or soleus muscle derived from 4 month-old mice. C2C12 MT-CM, but not undifferentiated myoblast CM prevented dex-induced cell apoptosis and was potent down to 0.1 % CM. The CM from EDL muscle electrically stimulated tetanically at 80 Hz was more potent (10 fold) in prevention of dex-induced osteocyte death than CM from soleus muscle stimulated at the same frequency or CM from EDL stimulated at 1 Hz. This suggests that electrical stimulation increases production of factors that preserve osteocyte viability and that type II fibers are greater producers than type I fibers. The muscle factor(s) appears to protect osteocytes from cell death through activation of the Wnt/β-catenin pathway, as MT-CM induces β-catenin nuclear translocation and β-catenin siRNA abrogated the positive effects of MT-CM on dex-induced apoptosis. We conclude that muscle cells naturally secrete factor(s) that preserve osteocyte viability.
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