Carotid artery intimal medial thickness, brachial artery flow-mediated vasodilation and cardiovascular risk factors in diabetic and non-diabetic indigenous Australians

Background: Indigenous Australians are at high risk for cardiovascular disease and type 2 diabetes. Carotid artery intimal medial thickness (CIMT) and brachial artery flow-mediated vasodilation (FMD) are ultrasound imaging based surrogate markers of cardiovascular risk. This study examines the relative contributions of traditional cardiovascular risk factors on CIMT and FMD in adult Indigenous Australians with and without type 2 diabetes mellitus. Method: One hundred and nineteen Indigenous Australians were recruited. Physical and biochemical markers of cardiovascular risk, together with CIMT and FMD were meausred for all subjects. Results: Fifty-three Indigenous Australians subjects (45%) had type 2 diabetes mellitus. There was a significantly greater mean CIMT in diabetic versus non-diabetic subjects (p = 0.049). In the non-diabetic group with non-parametric analyses, there were significant correlations between CIMT and: age (r = 0.64, p < 0.001), systolic blood pressure (r = 0.47, p < 0.001) and non-smokers (r = -0.30, p = 0.018). In the diabetic group, non-parametric analysis showed correlations between CIMT, age (r = 0.36, p = 0.009) and duration of diabetes (r = 0.30, p = 0.035) only. Adjusting forage, sex, smoking and history of cardiovascular disease, Hb(A1c) became the sole significant correlate of CIMT (r = 0.35,p = 0.01) in the diabetic group. In non-parametric analysis, age was the sole significant correlate of FMD (r = -0.31,p = 0.013), and only in non-diabetic subjects. Linear regression analysis showed significant associations between CIMT and age (t = 4.6,p < 0.001), systolic blood pressure (t = 2.6, p = 0.010) and Hb(A1c) (t = 2.6, p = 0.012), smoking (t = 2.1, p = 0.04) and fasting LDL-cholesterol (t = 2.1, p = 0.04). There were no significant associations between FMD and examined cardiovascular risk factors with linear regression analysis Conclusions: CIMT appears to be a useful surrogate marker of cardiovascular risk in this sample of Indigenous Australian subjects, correlating better than FMD with established cardiovascular risk factors. A lifestyle intervention programme may alleviate the burden of cardiovascular disease in Indigenous Australians by reducing central obesity, lowering blood pressure, correcting dyslipidaemia and improving glycaemic control. CIMT may prove to be a useful tool to assess efficacy of such an intervention programme. (c) 2004 Elsevier Ireland Ltd. All rights reserved.

Reflexive optokinetic nystagmus in younger and older observers under photopic and mesopic viewing conditions

PURPOSE. To investigate the effect of age on optokinetic nystagmus (OKN) in response to stimuli designed to preferentially stimulate the M-pathway. METHOD. OKN was recorded in 10 younger (32.3 +/- 5.98 years) and 10 older (65.6 +/- 6.53) subjects with normal vision. Vertical gratings of 0.43 or 1.08 cpd drifting at 5 degrees/s or 20 degrees/s and presented at either 8% or 80% contrast were displayed on a large screen as full-field stimulation, central stimulation within a central Gaussian-blurred window of 15 diameter, or peripheral stimulation outside this window. All conditions apart from the high-contrast condition were presented in a random order at two light levels, mesopic (1.8 cdm(-2)) and photopic (71.5 cdm(-2)). RESULTS. Partial-field data indicated that central stimulation, mesopic light levels, and lower temporal frequency each significantly increased slow-phase velocity (SPV). Although there was no overall difference between groups for partial-field stimulation, full-field stimulation, or low-contrast stimulation, a change in illumination revealed a significant interaction with age: there was a larger decrease in SPV going from photopic to mesopic conditions for the older group than the younger group, especially for higher temporal frequency stimulation. CONCLUSIONS. OKN becomes reflexive in conditions conducive to M-pathway stimulation, and this rOKN response is significantly diminished in older healthy adults than in younger healthy adults, indicative of decreased M-pathway sensitivity.

Reflexive OKN with partial and full field stimulation: Effects of age and light level

We recorded reflexive OKN in ten younger (32.3±5.98 years) and older (65.6±6.53) visually normal subjects under viewing conditions designed to differentiate M-pathway functioning from other pathways. Subjects were required to gaze straight ahead while viewing vertical gratings of either 0.43 or 1.08 cpd, drifting at either 5 or 20°/sec and presented at either 8 or 80% contrast. Gratings were presented as full field stimulation, central stimulation or peripheral (>15°) stimulation. The order of presentation of conditions was pseudo-randomised at two blocked light levels: ‘mesopic’ or twilight conditions (1.8 cdm-2) and ‘photopic’ or full light conditions (71.5 cdm-2). For the partial fields, central stimulation, mesopic light level, lower temporal frequencies (i.e. number of stripes passing per second) each contributed to greater OKN strength as measured by slow-phase velocity (SPV). For full field stimulation, and especially for higher temporal frequencies and low contrast, there was a significant interaction between age group × light level (p = 0.017): SPV diminished much more among the older than the younger group for the twilight condition compared to full light. Such a clear diminution in M-pathway sensitivity revealed by OKN response has important implications for everyday situations like crash avoidance under twilight driving conditions.

A reflexive course for Masters students to understand and plan their own continuing professional development

Continuing Professional Development (CPD) is seen as a vital part of a professional engineer’s career, by professional engineering institutions as well as individual engineers. Factors such as ever-changing workforce requirements and rapid technological change have resulted in engineers no longer being able to rely just on the skills they learnt at university or can pick up on the job; they must undergo a structured professional development with clear objectives to develop further professional knowledge, values and skills. This paper presents a course developed for students undertaking a Master of Engineering or Master of Project Management at the University of Queensland. This course was specifically designed to help students plan their continuing professional development, while developing professional skills such as communication, ethical reasoning, critical judgement and the need for sustainable development. The course utilised a work integrated learning pedagogy applied within a formal learning environment, and followed the competency based chartered membership program of Engineers Australia, the peak professional body of engineers in Australia. The course was developed and analysed using an action learning approach. The main research question was “Can extra teaching and learning activities be developed that will simulate workplace learning?” The students continually assessed and reflected upon their current competencies, skills and abilities, and planed for the future attainment of specific competencies which they identified as important to their future careers. Various evaluation methods, including surveys before and after the course, were used to evaluate the action learning intervention. It was found that the assessment developed for the course was one of the most important factors, not only in driving student learning, as is widely accepted, but also in changing the students’ understandings and acceptance of the need for continuous professional development. The students also felt that the knowledge, values and skills they developed would be beneficial for their future careers, as they were developed within the context of their own professional development, rather than to just get through the course. © 2005, American Society for Engineering Education

Alpha-lipoic acid does not acutely affect resistance and conduit artery function or oxidative stress in healthy men

Aims Alpha-lipoic acid (ALA) is a thiol compound with antioxidant properties used in the treatment of diabetic polyneuropathy. ALA may also improve arterial function, but there have been scant human trials examining this notion. This project aimed to investigate the effects of oral and intra-arterial ALA on changes in systemic and regional haemodynamics, respectively. Methods In study 1, 16 healthy older men aged 58 +/- 7 years (mean +/- SD) received 600 mg of ALA or placebo, on two occasions 1 week apart, in a randomized cross-over design. Repeated measures of peripheral and central haemodynamics were then obtained for 90 min. Central blood pressure and indices of arterial stiffness [augmentation index (AIx) and estimated aortic pulse wave velocity] were recorded non-invasively using pulse wave analysis. Blood samples obtained pre- and post-treatments were analysed for erythrocyte antioxidant enzyme activity, plasma nitrite and malondialdehyde. In study 2 the effects of incremental cumulative doses (0.5, 1.0, 1.5 and 2.0 mg ml(-1) min(-1)) of intra-arterial ALA on forearm blood flow (FBF) were assessed in eight healthy subjects (aged 31 +/- 5 years) by conventional venous occlusion plethysmography. Results There were no significant changes on any of the central or peripheral haemodynamic measures after either oral or direct arterial administration of ALA. Plasma ALA was detected after oral supplementation (95% confidence intervals 463, 761 ng ml(-1)), but did not alter cellular or plasma measures of oxidative stress. Conclusions Neither oral nor intra-arterial ALA had any effect on regional and systemic haemodynamics or measures of oxidative stress in healthy men.

The relative importance of vascular structure and function in predicting cardiovascular events

OBJECTIVES We sought to assess the prognostic utility of brachial artery reactivity (BAR) in patients at risk of cardiovascular events. BACKGROUND Impaired flow-mediated vasodilation measured by BAR is a marker of endothelial dysfunction. Brachial artery reactivity is influenced by risk factors and is responsive to various pharmacological and other treatments. However, its prognostic importance is uncertain, especially relative to other predictors of outcome. METHODS A total of 444 patients were prospectively enrolled to undergo BAR and follow-up. These patients were at risk of cardiovascular events, based on the presence of risk factors or known or suspected cardiovascular disease. We took a full clinical history, performed BAR, and obtained carotid intima-media thickness (IMT) and left ventricular mass and ejection fraction. Patients were followed up for cardiovascular events and all-cause mortality. Multivariate Cox regression analysis was performed to assess the independent association of investigation variables on outcomes. RESULTS The patients exhibited abnormal BAR (5.2 +/- 6.1% [mean +/- SD]) but showed normal nitrate-mediated dilation (9.9 +/- 7.2%) and normal mean IMT (0.67 +/- 0.12 mm [average]). Forty-nine deaths occurred over the median follow-up period of 24 months (interquartile range 10 to 34). Patients in the lowest tertile group of BAR (<2%) had significantly more events than those in the combined group of highest and mid-tertiles (p = 0.029, log-rank test). However, mean IMT (rather than flow-mediated dilation) was the vascular factor independently associated with mortality, even in the subgroup (n = 271) with no coronary artery disease and low risk. CONCLUSIONS Brachial artery reactivity is lower in patients with events, but is not an independent predictor of cardiovascular outcomes in this cohort of patients. (C) 2004 by the American College of Cardiology Foundation.

Irja' ila Nafsika: Suhraward's apperception of the self in light of Avicenna

Shihāb al-Dīn Suhrawardī (d.687/1191) proposed a theory of apperception that constitutes the core of his “illuminative” epistemology. His theory of apperception purports to account for the soul’s immediate, reflexive, and unmediated knowledge of its own essence. Apperception may be defined as the direct experience the soul has of its essence. A closer examination of the Avicennan tradition (Avicenna died in 420/1037) reveals the existence of a number of arguments for the demonstration of an apperception of the self/soul similar to the arguments Suhrawardī later proposes. Contrary to admitted views, Avicenna had tackled issues related to the soul’s apperception, a type of perception distinct from the soul’s intellection of its essence. Avicenna alluded to the existence of a mode of perception specific to the soul that would guarantee both the soul’s unity and its personal identity. This apperception is defined as an unmediated presence of the soul to itself. These elements recur in Suhrawardī’s theory of apperception and numerous versions of Avicenna’s arguments for the demonstration of the presential nature of apperception

Vasodilator mechanisms in the dorsal aorta of the giant shovelnose ray, Rhinobatus typus (Rajiformes; Rhinobatidae)

This study investigated the nature of vasodilator mechanisms in the dorsal aorta of the giant shovelnose ray, Rhinobatus typus. Anatomical techniques found no evidence for an endothelial nitric oxide synthase, but neural nitric oxide synthase was found to be present in the perivascular nerve fibres of the dorsal aorta and other arteries and veins using both NADPH-diaphorase staining and immunohistochemistry with a specific neural NOS antibody. Arteries and veins both contained large nNOS-positive nerve trunks from which smaller nNOS-positive bundles branched and formed a plexus in the vessel wall. Single, varicose nNOS-positive nerve fibres were present in both arteries and veins. Within the large bundles of both arteries and veins, groups of nNOS-positive cell bodies forming microganglia were observed. Double-labelling immunohistochemistry using an antibody to tyrosine hydroxylase showed that nearly all the NOS nerves were not sympathetic. Acetylcholine always caused constriction of isolated rings of the dorsal aorta and the nitric oxide donor, sodium nitroprusside, did not mediate any dilation. Addition of nicotine (3 x 10(-4) M) to preconstricted rings caused a vasodilation that was not affected by the nitric oxide synthase inhibitor, L-NNA (10(-4) M), nor the soluble guanylyl cyclase inhibitor, ODQ (10(-5) M). This nicotine-mediated vasodilation was, therefore, not due to the synthesis and release of NO. Disruption of the endothelium significantly reduced or eliminated the nicotine-mediated vasodilation. In addition. indomethacin (10(-5) M), an inhibitor of cyclooxygenases, significantly increased the time period to maximal dilation and reduced, but did not completely inhibit the nicotine-mediated vasodilation. These data support the hypothesis that a prostaglandin is released from the vascular endothelium of a batoid ray, as has been described previously in other groups of fishes. The function of the nitrergic innervation of the blood vessels is not known because nitric oxide does not appear to regulate vascular tone. (C) 2003 Elsevier Inc. All rights reserved.