Western Sahara: Separating fact from fiction in the independence debate

As the Western Sahara continues to make its case for self-determination, LSE’s Desiree Shayer-McLeod points out where Morocco is going wrong in its case for sovereignty over the region

Chromium carcinogenesis: Mechanisms and biomonitoring

Whilst chromium (Cr) compounds (particularly water soluble complexes) have long been recognised as carcinogens, much information is still missing about how these agents exert their mutagenic, carcinogenic, and deoxyribonucleic acid (DNA) damaging effects. The activation of Cr(VI) by intracellular reductants such as glutathione (GSH), ascorbic acid (AsA) and cysteine (Cys), among others, is crucial for the mediation of its DNA damaging effects. Studies into the interaction of Cr(VI) with isolated DNA in the presence of GSH were principally concerned with identifying the existence of a mutual mechanistic pathway for the mediation of more than one type of prevalent DNA lesion. The role of reactive oxygen species in the mediation of Cr(VI)-induced DNA damage was considered with particular emphasis on single strand breaks (SSB) and apurinic/apyrimidinic sites (AP-sites). The potential sites of interaction of damaging species with the DNA macromolecule were considered, and from these and other studies several conclusions were drawn. It is demonstrated that Cr-DNA adducts can be formed independently of the reaction pathways giving rise to SSB and AP- sites, and that Cr(V), and possibly Cr(IV) species, as well as hydrolysing Cr(III)/GSH complexes are responsible for the formation of Cr-DNA adducts. Evidence is also provided to support the hypothesis that DNA-phosphate groups are the binding site of Cr-DNA adducts. A bacterial mutation assay was employed to investigate the mutagenic potential of different types of Cr(VI)-induced DNA damage and it was demonstrated that DNA lesions induced during the in vitro conversion of Cr(VI) by GSH can be fixed into mutations during replication and passed onto progeny cells. There is an apparent role for Cr-DNA adduct formation in this process and since Cr(III) species are involved in the mediation of this type of damage it is proposed that Cr(III) represents a species with the potential capacity to cause fixed mutations in cell lines. A novel whole animal model, involving the application of magnetic resonance imaging (MRI), was developed to enable levels of Cr compounds to be monitored in the lung. The technique was shown to be sensitive enough to detect amounts of Cr(III) as low as 5 μg per whole lung. In addition, this method was able to monitor the conversion of Cr(VI) to Cr(III) in situ despite post-mortem conditions; an important finding since it not only demonstrates the powerful reductive capacity of the lung but allows the detection of Cr(VI) which has been shown to be the primary damaging species in Cr-induced carcinogenesis

Bringing CASE in from the cold: the teaching and learning of thinking

Thinking Science is a two-year program of professional development for teachers and thinking lessons for students in junior high school science classes. This paper presents research on the effects of Thinking Science on students’ levels of cognition in Australia. The research is timely with a general capability focused on critical thinking in the newly implemented F-10 curriculum in Australia. The design of the research was a quasi-experiment with pre and post-intervention cognitive tests conducted with participating students (n = 655) from nine cohorts in seven high schools. Findings showed significant cognitive gains compared with an age matched control group over the length of the program. Noteworthy, is a correlation between baseline cognitive score and school Index of Community Socio-Educational Advantage (ICSEA). We argue that the teaching of thinking be brought into the mainstream arena of educational discourse and the principles from evidence-based programs such as Thinking Science be universally adopted

Effects of a Mathematics Cognitive Acceleration Program on Student Achievement and Motivation

This paper presents the effects of a cognitive acceleration program in mathematics classes on Tongan students’ achievements, motivation and self-regulation. Cognitive Acceleration in Mathematics Education (CAME) is a program developed at King’s College and implemented worldwide with the aim of improving students’ thinking skills, mathematics performance and attitudes. The first author adapted the program materials to Tongan educational context and provided support to participating teachers for 8 months. This study employed a quasi-experimental design with 219 Year 8 students as the experimental group and 119 Year 8 students as the comparison group. There were a significant differences in the mean scores between the pre-test and post-test of the three instruments that were employed in the study, indicating that learning mathematics under the CAME program had a positive effect on levels of students’ self-regulation, motivation and mathematics achievement. Students also reported changes to the ways they learn mathematics