Roisin Kelly-Laubscher

Cardiac preconditioning with sphingosine-1-phosphate requires activation of signal transducer and activator of transcription-3.

Summary Aims Sphingosine-1-phosphate (S1P) is a cardioprotective agent. Signal transducer and activator of transcription 3 (STAT-3) is a key mediator of many cardioprotective agents. We aimed to explore whether STAT-3 is a key mediator in S1P-induced preconditioning. Methods Langendorff-perfused hearts from Wistar rats and wild-type or cardiomyocyte-specific STAT-3 knockout mice were pre-treated with S1P (10 nmol/l), with or without the STAT-3 pathway inhibitor AG490, before an ischaemia–reperfusion insult. Triphenyltetrazolium chloride and Evans blue staining were used for the determination of infarct size. Western blot analysis was carried out on the S1P pre-treated hearts for detection of cytosolic, nuclear and mitochondrial phosphorylated and total STAT-3 proteins. Results Pre-treatment with S1P decreased the infarct size in isolated rat (5 ± 3% vs control 26 ± 8%, p < 0.01) and wild-type mouse hearts (13 ± 1% vs control 33 ± 3%, p < 0.05). This protective effect was abolished in the rat hearts pre-treated with AG490 (30 ± 10%, p = ns vs control) and in the hearts from STAT-3 knockout mice (35 ± 4% vs control 30 ± 3%, p = ns). Levels of phosphorylated STAT-3 were significantly increased in both the nuclear (p < 0.05 vs control) and mitochondrial (p < 0.05 vs control) fractions in the S1P pre-treated hearts, but remained unchanged in the cytosolic fraction (p = ns vs control). Conclusion These novel results demonstrate that pharmacological preconditioning with S1P in the isolated heart is mediated by activation of mitochondrial and nuclear STAT-3, therefore suggesting that S1P may be a novel therapeutic target to modulate mitochondrial and nuclear function in cardiovascular disease in order to protect the heart against ischaemia–reperfusion.

Differences in Curriculum Structure between High School and University Biology: The Implications for Epistemological Access

Despite doing well in biology at high school, some students struggle with the same subject at university level. This can have implications for epistemological access - access to knowledge that allows students to remain at university. Therefore, it is important to identify factors that may be causing this problem. We propose that one such factor may be differences in the structure of knowledge between the two levels. Therefore, this paper will assess some of the differences in the structuring of knowledge that exist between a high school and a university biology curriculum. To do this, a section of a high school and a university textbook which cover the same topic will be analysed using one aspect of Legitimation Code Theory called Semantics. Our findings suggest that there is a mismatch between the semantic range students are expected to navigate at university and that demanded by high school biology, and that this may pose a stumbling block to students gaining epistemological access to first-year study at university. If this is indeed the case, then pedagogic interventions which explicitly address this may contribute to improving undergraduate student retention and throughput rates at university.

Lack of cardioprotection by single-dose magnesium prophylaxis on isoprenaline-induced myocardial infarction in adult Wistar rats.

Summary Aim Magnesium (Mg2+) is effective in treating cardiovascular disorders such as arrhythmias and pre-eclampsia, but its role during myocardial infarction (MI) remains uncertain. In this study, we investigated the effects of Mg2+ pre-treatment on isoprenaline (ISO)-induced MI in vivo. Methods Rats divided into four groups were each pre-treated with either MgSO4 (270 mg/kg intraperitoneally) or an equivalent volume of physiological saline, prior to the ISO (67 mg/kg subcutaneously) or saline treatments. One day post-treatment, the electrocardiogram and left ventricular blood pressures were recorded. Infarcts were determined using 2,3,5-triphenyltetrazolium chloride staining, and serum markers of lipid peroxidation were measured with spectrophotometric assays. Results Mg2+ pre-treatment neither altered the ISO-induced infarct size compared with ISO treatment alone (p > 0.05), nor reversed the low-voltage electrocardiogram or the prominent Q waves induced by ISO, despite a trend to decreased Q waves. Similarly, Mg2+ did not prevent the ISO-induced decrease in peak left ventricular blood pressure or the decrease in minimal rate of pressure change. Mg2+ did not reverse the ISO-induced gain in heart weight or loss of body weight. Neither ISO nor Mg2+ altered the concentrations of lipid peroxidation markers 24 hours post MI induction. Conclusion Although Mg2+ had no detrimental effects on electrical or haemodynamic activity in ISO-induced MI, the lack of infarct prevention may detract from its utility in MI therapy.

Supporting the teaching of the visual literacies in the earth and life sciences in higher education

ABSTRACT Internationally, there has been increasing emphasis on the teaching of the academic literacies, particularly reading and writing, in higher education institutions. However, recent research is highlighting the need for more explicit teaching of multimodal forms of communication, such as the visual literacies, in undergraduate courses in a wide range of disciplines such as the sciences, engineering and architecture. The research recognises that this is an area of academic literacy teaching that has often been neglected. This article draws on the findings of a research project which set out to understand both the multimodal literacy requirements and current practices in the teaching of these literacies in the earth and life sciences at a South African university. Three key themes are discussed: learning to see like a scientist, the importance of learning by switching between and integrating different modes of representation and teaching the conventions of representation in the sciences. The conclusion proposes ways for academic developers to work with staff to develop more explicit ways of teaching the visual literacies.

Effects of acute pre-treatment with ethanolamine on isoprenalineinduced myocardial infarction in adult Wistar rats

Ethanolamine (Etn), a biogenic amine, protects isolated hearts against MI, but its effects in vivo are unknown. In this study, we investigated the effects of Etn pretreatment on isoprenaline (ISO)-induced MI in vivo. Wistar rats were treated with either Etn (10mg.kg-1, i.p.) or saline, prior to either ISO (67mg.kg-1, s.c.) or saline. Haemodynamic- and electrocardiographic parameters were recorded under anaesthesia, 24 hours post-treatment with ISO. Infarct sizes were determined by triphenyltetrazolium chloride staining. Oxidative stress plasma parameters, conjugated dienes (CD) and thio-barbituric acid reactive substances (TBARS), were measured by spectrophotometric analysis. Etn decreased ISO-induced pathological Q-waves, but had no effect on ISO-induced low-voltage electrocardiogram. In addition, Etn decreased overall mortality induced by ISO treatment. However, Etn did not prevent ISO-induced infarction or the systolic- and diastolic hypotensive effects. Etn also enhanced the ISO-induced increase in heart-to-body weight ratio, and reversed the decrease in lungs-to-body weight ratio. Neither ISO nor Etn altered CD or TBARS. These results suggest that, despite a tendency to modulate cardiac electrical activity, Etn did not prevent ISO-induced MI or myocardial dysfunction in vivo.

The potential of student narratives to enhance quality in higher education

Abstract University policies are increasingly developed with reference to students’ learning experiences, with a focus on the concept of the ‘student voice’. Yet the ‘student voice’ is difficult to define and emphasis is often placed on numerical performance indicators. A diverse student population has wide-ranging educational experiences, which may not be easily captured within the broad categories provided by traditional survey tools, which can drown out the rich, varied and gradual processes of individual development. There is no single tool that can be used to measure students’ experiences. This paper draws on findings from four narrative inquiry studies, carried out in the United Kingdom, Australia, South Africa and New Zealand, to illustrate how a narrative approach could be used to complement performance indicators. This provides a richer context for educators’ understanding of students’ experiences and for supporting and setting institutional agendas.

Beneficial Effects of Magnesium Treatment on Heart Rate Variability and Cardiac Ventricular Function in Diabetic Rats

Background: Diabetes mellitus induces life-threatening cardiovascular complications such as cardiac autonomic neuropathy and ventricular dysfunction and is associated with hypomagnesemia. In this study, we investigated the short-term effects of magnesium (Mg2+) treatment on streptozotocin (STZ)-induced diabetic cardiac complications. Methods: Adult Wistar rats were treated once with STZ (50 mg/kg, intraperitoneally [ip]) or vehicle (citrate) and then daily for 7 days with MgSO4 (270 mg/kg, ip) or saline. On the eighth day, in vivo tail-pulse plethysmography was recorded for heart rate variability (HRV) analysis, and ex vivo Langendorff-based left ventricular (LV) pressure–volume parameters were measured using an intraventricular balloon. Measurements of plasma lipid and Mg2+ levels as well as blood glucose and cardiac tissue Mg2+ levels were also performed. Results: Treatment with Mg2+ prevented diabetes-induced alterations in the standard deviation of the averages of normal-to-normal (NN) intervals (SDANN), root mean square differences of successive NN intervals (RMSSD), heart rate, and low-frequency (LF) power–high-frequency (HF) power ratio. In addition, Mg2+ restored orthostatic stress-induced changes in SDANN, RMSSD, and LF–HF ratio in diabetic rats. In isolated hearts, Mg2+ reversed the diabetes-induced decrease in LV end-diastolic elastance and the right shift of end-diastolic equilibrium volume intercept, without altering LV-developed pressure or end-systolic elastance. However, Mg2+ did not prevent the elevation in blood glucose, total cholesterol, and triglycerides or the decrease in high-density lipoprotein cholesterol in diabetes. Plasma- or cardiac tissue Mg2+ was not different among the treatment groups. Conclusion: These results suggest that Mg2+ treatment may attenuate diabetes-induced reduction in HRV and improve LV diastolic distensibility, without preventing hyperglycemia and dyslipidemia. Thus, Mg2+ may have a modulatory role in the early stages of diabetic cardiovascular complications.