In vitro studies have shown that hydrogen peroxide (H2O2) produced by high-concentration ascorbate and cell culture medium iron efficiently kills cancer cells. This provided the rationale for clinical trials of high-dose intravenous ascorbate-based treatment for cancer. A drawback in all the in vitro studies was their failure to take into account the in vivo concentration of iron to supplement cell culture media which are characterized by low iron content. Here we showed, using two prostate cancer cell lines (LNCaP and PC-3) and primary astrocytes, that the anticancer/cytotoxic effects of ascorbate are completely abolished by iron at physiological concentrations in cell culture medium and human plasma. A detailed examination of mechanisms showed that iron at physiological concentrations promotes both production and decomposition of H2O2. The latter is mediated by Fenton reaction and prevents H2O2 accumulation. The hydroxyl radical, which is produced in the Fenton reaction, is buffered by extracellular proteins, and could not affect intracellular targets like H2O2. These findings show that anticancer effects of ascorbate have been significantly overestimated in previous in vitro studies, and that common cell culture media might be unsuitable for redox research.

Purpose The purpose of this paper is to examine the direction and strength of the influence of inherent factors of the theory of planned behaviour (TPB) and to extend a model with the variable “uniqueness-seeking lifestyle” to better explain the variance in the intention to purchase organic food and the referent actual behaviour. Design/methodology/approach The authors empirically investigated what drives consumers to purchase organic food using structural equation modelling in AMOS. The research was based on an in-person survey carried out on a convenient sample of 411 primary household shoppers in Croatia. Findings The study was able to capture not only the influence of inherent factors in TPB and the extension variable (all proposed constructs were shown to have a significant positive influence on intention, and intention had a significant positive influence on actual behaviour), but also the indirect and mediation effects of the variables within the model, which explain 87 per cent of the variance in intention and 21 per cent of the variance in actual behaviour. Originality/value This study provides empirical evidence of the role that desired uniqueness plays in a situation involving the purchase of organic food and responds to the requests of many researchers to investigate beyond intention and to try to identify what influences actual behaviour. This study proposes a new way of measuring actual purchases by asking a respondent to consider their actual purchase in different product categories. Furthermore, this research proposes measuring intention as a latent variable that consists of the variable “willingness to pay more” as well as the “commitment” to the decision regardless of any perceived obstacles.

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The spontaneously active Br neuron from the brain-subesophageal ganglion complex of the garden snail Helix pomatia rhythmically generates regular bursts of action potentials with quiescent intervals accompanied by slow oscillations of membrane potential. We examined the involvement of the Na(+)/K(+) pump in modulating its bursting activity by applying a static magnetic field. Whole snail brains and Br neuron were exposed to the 10-mT static magnetic field for 15 min. Biochemical data showed that Na(+)/K(+)-ATPase activity increased almost twofold after exposure of snail brains to the static magnetic field. Similarly, (31)P NMR data revealed a trend of increasing ATP consumption and increase in intracellular pH mediated by the Na(+)/H(+) exchanger in snail brains exposed to the static magnetic field. Importantly, current clamp recordings from the Br neuron confirmed the increase in activity of the Na(+)/K(+) pump after exposure to the static magnetic field, as the magnitude of ouabain's effect measured on the membrane resting potential, action potential, and interspike interval duration was higher in neurons exposed to the magnetic field. Metabolic pathways through which the magnetic field influenced the Na(+)/K(+) pump could involve phosphorylation and dephosphorylation, as blocking these processes abolished the effect of the static magnetic field.