Do Dietary Habits Influence Trace Elements Release from Fixed Orthodontic Appliances?

The objective was to investigate the effect of dietary habits on the release of Cr and Ni ions from orthodontic appliances by hair mineral analysis. Patients (N = 47) underwent electronic questionnaire survey to investigate the effect of dietary habits on Cr and Ni levels in hair. The research was carried out on hair sampled at the beginning and in the 4th, 8th, and 12th months of the treatment. The content of Cr and Ni in the collected samples was determined by ICP-OES. The study showed that consumption of acidic dietary products may have the effect on increasing the release of Cr and Ni ions from orthodontic appliances. The release of Cr from orthodontic appliances in patients who consumed fruit juice, coffee, yoghurt, and vinegar was higher. The coefficients enabling comparison of metal ions release pattern at a given sampling points were defined. The comparison of the coefficients yielded the information on the possible magnification of metal ions released as the result of the additional factor consumption of acidic food or drink that intensifies metal ions release. The following magnification pattern was found for chromium: coffee (7.57 times) > yoghurt (2.53) > juice (1.86) > vinegar (1.08), and for nickel: vinegar (2.2) > coffee (1.22) > juice (1.05). Yoghurt did not intensify the release of nickel. Concluding, orthodontic patients should avoid drinking/eating coffee, yoghurt, fruit juices, and vinegar.     

Induction time and reversibility of changes in Daphnia life history caused by the presence of fish

Two experiments were run, to demonstrate how Daphnia life historychanges in the response to fish kairomone, depending on at whichontogenetic stage the simulated presence of fish appears ordisappears. Exposures of Daphnia, starting from different ontogeneticstages, to the fish kairomone showed that the period betweenthe initiation of phenotypic changes induced by the presenceof fish and their adaptive expression in Daphnia varies fromone instar (2–3 days) in the case of size at first reproductionto five instars (about 7 days) in the case of age at first reproduction.Removing the fish kairomone in different ontogenetic stagesshowed, in turn, that if a proximal factor that induced an anti-predatormechanism disappears and is not detected for at least four instars,Daphnia may withdraw from former changes (e.g. maturation whenlarger). It is suggested that the moment of the final ‘decision’regarding size at first reproduction cannot be attributed toa specific instar, but rather to a given moment in the Daphnialife cycle that is not related to any particular developmentalinstar but rather to the instantaneous level of resources thatcan be allocated to the reproduction.     

Crucial role of lysosomal iron in the formation of dinitrosyl iron complexes in vivo

Dinitrosyl non-heme–iron complexes (DNIC) are found in many nitric oxide producing tissues. A prerequisite of DNIC formation is the presence of nitric oxide, iron and thiol/imidazole groups. The aim of this study was to investigate the role of the cellular labile iron pool in the formation of DNIC in erythroid K562 cells. The cells were treated with a nitric oxide donor in the presence of a permeable (salicylaldehyde isonicotinoyl hydrazone) or a nonpermeable (desferrioxamine mesylate) iron chelator and DNIC formation was recorded using electron paramagnetic resonance. Both chelators inhibited DNIC formation up to 50% after 6 h of treatment. To further investigate the role of lysosomal iron in DNIC formation, we prevented lysosomal proteolysis by pretreatment of whole cells with NH₄Cl. Pretreatment with NH₄Cl inhibited the formation of DNIC in a time-dependent manner that points to the importance of the degradation of iron metalloproteins in DNIC formation in vivo. Fractionation of the cell content after treatment with the nitric oxide donor revealed that DNIC is formed predominantly in the endosomal/lysosomal fraction. Taken together, these data indicate that lysosomal iron plays a crucial role in DNIC formation in vivo. Degradation of iron-containing metalloproteins seems to be important for this process.     

Adsorption and phase transitions in adsorbed systems: structural properties of CCl<Subscript>4</Subscript> layers adsorbed on a graphite surface

We present the results of simulations of a CCl₄ monolayer adsorbed on a graphite surface. The CCl₄ molecule was represented either by a shapeless superatom or by its atomic sites. The simulations were carried out over a large range of temperatures, from 20 K up to 340 K. We address the following problems: (1) the influence of molecular shape on the structure and stability of phases (particularly at low temperatures), and (2) the influence of the graphite corrugation on layer stability and mechanism of phase transitions. In particular, we discuss the possibility and conditions of the appearance of hexatic phase in the system. Figure Temperature dependence of Φ6 order parameter for CCl₄ monolayer adsorbed onsmooth and corrugated surfaces, in the spherical Lennard Jones (LJ) approximation.For comparison, the order parameter calculated for MacDonald’s five-site potential is also presented     

Characterization of the Role of β-Carotene 9,10-Dioxygenase in Macular Pigment Metabolism

A family of enzymes collectively referred to as carotenoid cleavage oxygenases is responsible for oxidative conversion of carotenoids into apocarotenoids, including retinoids (vitamin A and its derivatives). A member of this family, the β-carotene 9,10-dioxygenase (BCO2), converts xanthophylls to rosafluene and ionones. Animals deficient in BCO2 highlight the critical role of the enzyme in carotenoid clearance as accumulation of these compounds occur in tissues. Inactivation of the enzyme by a four-amino acid-long insertion has recently been proposed to underlie xanthophyll concentration in the macula of the primate retina. Here, we focused on comparing the properties of primate and murine BCO2s. We demonstrate that the enzymes display a conserved structural fold and subcellular localization. Low temperature expression and detergent choice significantly affected binding and turnover rates of the recombinant enzymes with various xanthophyll substrates, including the unique macula pigment meso-zeaxanthin. Mice with genetically disrupted carotenoid cleavage oxygenases displayed adipose tissue rather than eye-specific accumulation of supplemented carotenoids. Studies in a human hepatic cell line revealed that BCO2 is expressed as an oxidative stress-induced gene. Our studies provide evidence that the enzymatic function of BCO2 is conserved in primates and link regulation of BCO2 gene expression with oxidative stress that can be caused by excessive carotenoid supplementation.