Neuroprotectant effects of iso-osmolar D-mannitol to prevent Pacific ciguatoxin-1 induced alterations in neuronal excitability: A comparison with other osmotic agents and free radical scavengers

The basis for the neuroprotectant effect of D-mannitol in reducing the sensory neurological disturbances seen in ciguatera poisoning, is unclear. Pacific ciguatoxin-1 (P-CTX-1), at a concentration 10 nM, caused a statistically significant swelling of rat sensory dorsal root ganglia (DRG) neurons that was reversed by hyperosmolar 50 MM D-mannitol. However, using electron paramagnetic resonance (EPR) spectroscopy, it was found that P-CTX-1 failed to generate hydroxyl free radicals at concentrations of toxin that caused profound effects on neuronal excitability. Whole-cell patch-clamp recordings from DRG neurons revealed that both hyper- and iso-osmolar 50 MM D-mannitol prevented the membrane depolarisation and repetitive firing of action potentials induced by P-CTX-1. In addition, both hyper- and iso-osmolar 50 MM D-mannitol prevented the hyperpolarising shift in steady-state inactivation and the rise in leakage current through tetrodotoxin (TTX)-sensitive Na-v channels, as well as the increased rate of recovery from inactivation of TTX-resistant Nav channels induced by P-CTX-1. D-Mannitol also reduced, but did not prevent, the inhibition of peak TTX-sensitive and TTX-resistant I-Na amplitude by P-CTX-1. Additional experiments using hyper- and isoosmolar D-sorbitol, hyperosmolar sucrose and the free radical scavenging agents Trolox (R) and L-ascorbic acid showed that these agents, unlike D-mannitol, failed to prevent the effects of P-CTX-1 on spike electrogenesis and Na-v channel gating. These selective actions of D-mannitol indicate that it does not act purely as an osmotic agent to reduce swelling of nerves, but involves a more complex action dependent on the Nav channel subtype, possibly to alter or reduce toxin association. (c) 2005 Elsevier Ltd. All rights reserved.

Quorum sensing, bacterial communication and new antibiotics [Editorial]

No Abstract

Spelling in adults: The combined influences of language skills and reading experience

One hundred and twelve university students completed 7 tests assessing word-reading accuracy, print exposure, phonological sensitivity, phonological coding and knowledge of English morphology as predictors of spelling accuracy. Together the tests accounted for 71% of the variance in spelling, with phonological skills and morphological knowledge emerging as strong predictors of spelling accuracy for words with both regular and irregular sound-spelling correspondences. The pattern of relationships was consistent with a model in which, as a function of the learning opportunities that are provided by reading experience, phonological skills promote the learning of individual word orthographies and structural relationships among words.

Enhancing Life in the Hyper-surveillance Mini-world of a Space Station: The Role of Situation Awareness, Communication, and Reality TV in the Life of Astronauts

This is the third article of a series entitled Astronauts as Audiences. In this article, we investigate the roles that situation awareness (SA), communications, and reality TV (including media communications) might have on the lives of astronauts in remote space communities. We examined primary data about astronauts’ living and working environments, applicable theories of SA, communications, and reality TV (including media communications). We then surmised that the collective application of these roles might be a means of enhancing the lives of astronauts in remote space communities.

Are country and culture values interchangeable? A case example using occupational stress and coping

Cross cultural research in occupational stress and coping has produced a wealth of knowledge. Although advances have been made, there are still problems to be solved. One of these problems is the confusion generated in the literature by researchers claiming that nation or country represents cultural values, and the use of the two terms interchangeably. It remains unclear whether this practice is correct. The present article reported on this by using 511 full-time employees from Australia, Singapore and Sri Lanka to study occupational stress and coping. Results revealed that cultural value paradigms (i.e. Individualism–Collectivism) were distributed across the three nations such that over 60% of participants were either high or low in both I–C paradigms. The findings also indicated that the relationship between cultural value paradigm and country impacted on stress and coping differently. The study shows that significant differences exist within countries as well as between countries, such that any attempt to equate ‘culture’ with ‘country’ becomes problematic. Therefore these findings established that country or nation is not the same as culture values and cannot be used interchangeably.

Disability's affect: Or, refugees, communication and community

Cultural theorists have given much attention recently to the notion of 'affect', yet such discussions have not seriously, if at all, raised the question of disability. However we would suggest that disability has very strong relationships with affect. In this paper we argue for the importance of rethinking affect and communication from the perspective of a critical, socio-political account of disability. To illustrate this, we look at affect and disability in two important cases of refugees in Australia.