Good reproducibility of heart rate variability after orthostatic challenge in patients with a history of acute coronary syndrome

BACKGROUND: Several parameters of heart rate variability (HRV) have been shown to predict the risk of sudden cardiac death (SCD) in cardiac patients. There is consensus that risk prediction is increased when measuring HRV during specific provocations such as orthostatic challenge. For the first time, we provide data on reproducibility of such a test in patients with a history of acute coronary syndrome. METHODS: Sixty male patients (65+/-8years) with a history of acute coronary syndrome on stable medication were included. HRV was measured in supine (5min) and standing (5min) position on 2 occasions separated by two weeks. For risk assessment relevant time-domain [standard deviation of all R-R intervals (SDNN) and root mean squared standard differences between adjacent R-R intervals (RMSSD)], frequency domain [low-frequency power (LF), high-frequency power (HF) and LF/HF power ratio] and short-term fractal scaling component (DF1) were computed. Absolute reproducibility was assessed with the standard errors of the mean (SEM) and 95% limits of random variation, and relative reproducibility by the intraclass correlation coefficient (ICC). RESULTS: We found comparable SEMs and ICCs in supine position and after an orthostatic challenge test. All ICCs were good to excellent (ICCs between 0.636 and 0.869). CONCLUSIONS: Reproducibility of HRV parameters during orthostatic challenge is good and comparable with supine position.

Acute alcohol ingestion and sympathetic neural responses during orthostatic stress in humans

Acute alcohol consumption has been reported to decrease mean arterial pressure (MAP) during orthostatic challenge, a response that may contribute to alcohol-mediated hypotension and eventually syncope. Muscle sympathetic nerve activity (MSNA) increases during orthostatic stress to help maintain MAP, yet the influence of alcohol on MSNA during orthostatic stress has not been determined. We hypothesized that alcohol ingestion would blunt arterial blood pressure and MSNA responses to progressive lower body negative pressure (LBNP). MAP, MSNA, and heart rate (HR) were recorded during progressive LBNP (-5, -10, -15, -20, -30, and -40 mmHg; 3 min/stage) in 30 subjects(age 24 ± 1 yrs). After an initial progressive LBNP protocol (pre-treatment), subjects were randomly assigned to consume alcohol (0.8g ethanol/kg body mass; n=15) or placebo (n=15) and then repeated the progressive LBNP protocol (post-treatment). Alcohol increased (drug × treatment, P ≤ 0.05) resting HR (59 ± 2 to 65 ± 2 beats/min) and MSNA (13 ± 3 to 19 ± 4 bursts/min) when compared to placebo. While alcohol increased MAP (83 ± 2 to 87 ± 2 mmHg), these increases were also observed with placebo (82 ± 2 to 88 ± 1 mmHg; treatment, P < 0.05; drug × treatment, P > 0.05). During progressive LBNP, a prominent decrease in MAP was observed after alcohol (drug × time × treatment, P < 0.05), but not placebo. There was also a significant attenuated response in forearm vascular resistance (FVR) during progressive LBNP (drug × time × treatment, P < 0.05). MSNA and HR increased during all LBNP protocols, but there were no differences between treatments or groups (drugs). In summary, acute alcohol ingestion induces an attenuation in blood pressure response during an orthostatic challenge, possibly due to the effect that alcohol has on impairing peripheral blood vessel constriction.

Involvement of the paraventricular nucleus (PVN) of hypothalamus in the cardiovascular alterations to head up tilt in conscious rats

We evaluated the involvement of paraventricular nucleus (PVN) in the changes in mean arterial pressure (MAP) and heart rate (HR) during an orthostatic challenge (head up tilt, HUT). Adult male Wistar rats, instrumented with guide cannulas to PVN and artery and vein catheters were submitted to MAP and HR recording in conscious state and induction of HUT. The HUT induced an increase in MAP and HR and the pretreatment with prazosin and atenolol blocked these effects. After inhibition of neurotransmission with cobalt chloride (1 mM/100 nl) into the PVN the HR parameters did not change, however we observed a decrease in MAP during HUT. Our data suggest the involvement of PVN in the brain circuitry involved in cardiovascular adjustment during orthostatic challenges. (C) 2011 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Sex differences in heart rate variability: a longitudinal study in international elite cross-country skiers

PURPOSE: Exercise-related sudden cardiac deaths (SCD) occur with a striking male predominance. A higher sympathetic tone in men has been suggested as risk factor for SCD. Elite athletes have the highest risk for exercise-related SCD. We aimed to analyze the autonomic nervous system of elite cross-country skiers from Norway, Russia and Switzerland in supine position and after orthostatic challenge in various training periods (TP). METHOD: Measurements of heart rate variability (HRV) were performed on a weekly basis over 1 year using an orthostatic challenge test with controlled breathing. Main outcome parameters were the high-frequency power in supine position (HFsupine) as marker of cardiac parasympathetic activity and the low-frequency/high-frequency power ratio after orthostatic challenge (LF/HFstand) as marker of cardiac sympathetic activation. Training intensity and duration were recorded daily and expressed as training strain. The training year was divided into three TPs. An average of weekly HRV measurements was calculated for each TP. RESULT: Female (n = 19, VO2max 62.0 +/- 4.6 ml kg(-1) min(-1), age 25.8 +/- 4.3 years) and male (n = 16, VO2max 74.3 +/- 6.3 ml kg(-1) min(-1), age 24.4 +/- 4.2 years) athletes were included. Training strain was comparable between sexes (all p > 0.05) and changed between TPs (all p < 0.05) while no HRV parameters changed over time. There were no sex differences in HFsupine while the LF/HFstand was significantly higher in male athletes in all TPs. CONCLUSION: For a comparable amount of training, male athletes showed constantly higher markers of sympathetic activity after a provocation maneuver. This may explain part of the male predominance in sports-related SCD.

From concept to embodiment : challenge and strategy

Facing with the difficulty in information propagation and synthesizing from conceptual to embodiment design, this paper introduces a function-oriented, axiom based conceptual modeling scheme. Default logic reasoning is exploited for recognition and reconstitution of conceptual product geometric and topological information. The proposed product modeling system and reasoning approach testify a methodology of "structural variation design", which is verified in the implementation of a GPAL (Green Product All Life-cycle) CAD system. The GPAL system includes major enhancement modules of a mechanism layout sketching method based on fuzzy logic, a knowledge-based function-to-form mapping mechanism and conceptual form reconstitution paradigm based on default geometric reasoning. A mechanical hand design example shows a more than 20 times increase in design efficacy with these enhancement modules in the GPAL system on a general 3D CAD platform.

A structured return to the 'Fourth Estate': interviews and inquiry that challenge entrenched authorities' 'knowledge'

Contemporary debates on the role of journalism in society are continuing the tradition of downplaying the role of proactive journalism - generally situated under the catchphrase of the Fourth Estate - in public policy making. This paper puts the case for the retention of a notion of a proactive form of journalism which can be broadly described as "investigative ", because it is important to the public policy process in modern democracies. It argues that critiques that downplay the potential of this form of journalism are flawed and overly deterministic. Finally. it seeks to illustrate how journalists can proactively inquire in ways that are relevant to the lives ofpeople in a range of settings, and that question elite sources in the interests ofthose people.

Sustainable suburbs : the developer’s challenge

As our cities expand, developers are transforming more and more land to create our suburbs of the future. Developers and government bodies have a golden opportunity to design suburbs that are not only great places to live, but also are environmentally sensitive and sustainable. This is a unique opportunity, as significant changes after development are constrained by the configuration of the subdivision, and then by the construction of the dwellings. This paper explores some of these issues by presenting initial findings from the CRCCI, Sustainable Subdivisions Project. The Project examines the drivers and barriers that land developers face when trying to achieve sustainable subdivisions. This paper will review the results from a series of industry interviews and workshops and explore possible ways forward. In addition, the possible effect on the way future land subdivision is managed and planned as a result of recent changes in the energy efficiency provisions of the Building Code of Australia will be explored. This paper highlights problems that both builders and land developers may face through poor subdivision design. Finally an innovative program being driven by a major land developer will be introduced. The program aims to deliver over 400 energy and water efficient homes through a series of compulsory and voluntary schemes that the developer is designing, funding and implementing. This program is the first large-scale development in Australia that demonstrates how developers can help achieve environmentally sensitive and sustainable suburbs of the future.

The ‘Get Marketer Challenge’: Engaging first year students in an introductory marketing course

Research on student engagement suggests courses that involve students in challenging, authentic tasks linking students to their peers and educators are associated with high levels of engagement. This paper presents an assessment innovation within a first year marketing course that was designed to promote student engagement. Currently in its pilot stage, the ‘Get Marketer Challenge’ is a constructively aligned, authentic assessment task; requiring student teams to solve a real-world marketing problem as part of a course-wide competition. Student enrolment data suggests the Get Marketer Challenge is an attractive assessment option that encourages students to enrol in the Marketing course. Educators have been surprised by the consistency and high level of effort expended by student teams. Students report the Get Marketer Challenge is an enjoyable assessment task that helped them to understand some of the challenges faced by marketers.

The Get Marketer Challenge Innovation: Challenging students using a tournament style competition

This paper presents an assessment innovation which used a tournament style competition to challenge and engage first year marketing students. The course-wide competition required student teams to solve real-world marketing problems for industry sponsors. Student feedback reflects enjoyment of the task and the competition, with students welcoming the opportunity to put theory into practice. Student attendance in the lectures and tutorials involving team presentations was improved. This structure can be adapted for any course with large enrolments. We recommend that instructors adopting a tournament structure consider grading mechanisms that promote equal effort and additional rewards, such as bonus marks, for teams progressing in subsequent rounds.

The Google online marketing challenge and research opportunities

The Google Online Marketing Challenge is an ongoing collaboration between Google and academics, to give students experiential learning. The Challenge gives student teams US$200 in AdWords, Google’s flagship advertising product, to develop online marketing campaigns for actual businesses. The end result is an engaging in-class exercise that provides students and professors with an exciting and pedagogically rigorous competition. Results from surveys at the end of the Challenge reveal positive appraisals from the three—students, businesses, and professors—main constituents; general agreement between students and instructors regarding learning outcomes; and a few points of difference between students and instructors. In addition to describing the Challenge and its outcomes, this article reviews the postparticipation questionnaires and subsequent datasets. The questionnaires and results are publicly available, and this article invites educators to mine the datasets, share their results, and offer suggestions for future iterations of the Challenge.

Early land grants and reservations : Any lessons from the Queensland experience for the sustainability challenge to land ownership

Environmentalists have called for a new property paradigm premised on the idea of land ownership as a delegated responsibility to manage land and resources for the public benefit. An examination of Crown freehold grants from the beginnings of settlement until the 1890s in Queensland shows that fee simple titles were granted subject to express conditions and reservations designed to reserve useful natural resources to the Crown, and to promote public purposes. Over time, legislative regulation of landowner’s rights rendered obsolete the use of express conditions and reservations in grants. One result of this change was that the inherently limited nature of fee simple ownership, and the communal obligations to which it is subject, are less transparent than in colonial times.