Nickel allergy in mice: enhanced sensitization capacity of nickel at higher oxidation states.

Attempts to induce contact hypersensitivity to nickel in mice using, e.g., Ni(II)Cl2 often failed. Here, we report that sensitization was achieved by injecting Ni(II)Cl2 in combination with either CFA or an irritant, such as SDS and PMA, or IL-12, or by administering nickel at higher oxidation states, i.e., Ni(III) and Ni(IV). Although Ni(II), given alone, was ineffective in T cell priming, it sufficed for eliciting recall responses in vivo and in vitro, suggesting that Ni(II) is able to provide an effective signal 1 for T cell activation, but is unable to provide an adequate signal 2 for priming. Immunization of mice with nickel-binding proteins pretreated with Ni(IV), but not with Ni(II), allowed them to generate nickel-specific CD4+ T cell hybridomas. Ni(II) sufficed for restimulation of T cell hybridomas; in this and other aspects as well, the hybridomas resembled the nickel-specific human T cell clones reported in the literature. Interestingly, restimulation of hybridomas did not require the original Ni(IV)-protein complex used for priming, suggesting either that the nickel ions underwent ligand exchange toward unknown self proteins or peptides or that nickel recognition by the TCR is carrier-independent. In conclusion, we found that Ni(III) and Ni(IV), but not Ni(II) alone, were able to sensitize naive T cells. Since both Ni(III) and Ni(IV) can be generated from Ni(II) by reactive oxygen species, released during inflammation, our findings might explain why in humans nickel contact dermatitis develops much more readily in irritated than in normal skin.     

Lignin as additive in polypropylene/coir composites: Thermal, mechanical and morphological properties

PP/CF composites were prepared and the effect of lignin incorporation in the presence and absence of compatibilizer (maleic anhydride grafted polypropylene, PP-g-MA) was investigated by means of mechanical, thermal and morphological properties. Lignin added to the composite was obtained by the Acetosolv process. The composites were prepared in a Haake torque rheometer and assessed by means of tensile testing, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed that in the absence of PP-g-MA, incorporation of lignin did not affect tensile strength and in its presence this property was reduced. Thermal analysis revealed that incorporation of lignin in the composites resulted in increase in both the initial thermal decomposition temperatures and oxidation induction times.     

The Dance of Power: Ritual and Agency among Unionized American Health Care Workers

The authors illustrate the roles of agency and structure as workers, management, and a union representative use ritual encounters for their own ends in an American hospital. They also discuss the symbolism of the union contract as a charter for ritual and indicate how it and the structure that defines it subvert the broader goals of the union.     

Impact of Colored Shade Nets on Biomass Production,Essential Oil Composition and Orientin and Isoorientin Content in Lippia gracilis Schauer

The objective of this study was to evaluate the effect of ChromatiNet on vegetative growth, total antioxidant capacity, phenolic and essential oils (EOs) composition of Lippia gracilis. The plants were cultivated under full sunlight, black, blue and red ChromatiNet. The flavonoid content and antioxidant capacity were quantified spectrophotometrically. The C-glycosylflavone isomers (orientin and isoorientin) were isolated and identified by conventional spectroscopic techniques and measured using high-performance liquid chromatography-diode array detection. The EO was analysed by gas chromatography and gas chromatography-mass spectrometry. Environment influenced growth, total antioxidant capacity and phytochemical levels. Shoot dry weight, thymol, carvacrol and (E)-caryophyllene were favoured under red and black ChromatiNet. Root growth, EOs, caryophyllene oxide, p-cymene, flavonoids, orientin and isoorientin were favoured in sunlight. Growth and accumulation of EOs, flavonoids and photosynthetic pigments increased under blue ChromatiNet. Therefore, Lippia gracilis plants have plasticity related to the spectral quality of light and it cultivate depends of the phytochemicals of interest.     

Phenylethynyl-Butyltellurium Inhibits the Sulfhydryl Enzyme Na+, K+-ATPase: An Effect Dependent on the Tellurium Atom

Organotellurium compounds are known for their toxicological effects. These effects may be associated with the chemical structure of these compounds and the oxidation state of the tellurium atom. In this context, 2-phenylethynyl-butyltellurium (PEBT) inhibits the activity of the sulfhydryl enzyme, δ-aminolevulinate dehydratase. The present study investigated on the importance of the tellurium atom in the PEBT ability to oxidize mono- and dithiols of low molecular weight and sulfhydryl enzymes in vitro. PEBT, at high micromolar concentrations, oxidized dithiothreitol (DTT) and inhibited cerebral Na⁺, K⁺-ATPase activity, but did not alter the lactate dehydrogenase activity. The inhibition of cerebral Na⁺, K⁺-ATPase activity was completely restored by DTT. By contrast, 2-phenylethynyl-butyl, a molecule without the tellurium atom, neither oxidized DTT nor altered the Na⁺, K⁺-ATPase activity. In conclusion, the tellurium atom of PEBT is crucial for the catalytic oxidation of sulfhydryl groups from thiols of low molecular weight and from Na⁺, K⁺-ATPase.