Effect of fatigue and hypohydration on gait characteristics during treadmill exercise in the heat while wearing firefighter thermal protective clothing.

This study compared the gait characteristics of individuals walking in heat while wearing firefighting equipment in fatigued and non-fatigued states. Nineteen subjects performed a 50-min treadmill protocol in a heated room while gait patterns were recorded using a digital video camcorder. Forty gait cycles were analyzed near the beginning (9 min) and at the end (39-49 min) of exercise. Spatio-temporal gait variables including step frequency, step length, swing time, stance time, cycle time and double-support time were determined. Gait variability was quantified by the standard deviation (SD) and coefficient of variation (CV) of each variable. Left-right symmetry was calculated using the symmetry index (SI) and symmetry angle (SA). Paired t-tests (alpha = 0.05) were performed to identify difference between the beginning and the end of the protocol for each measured variable. Spatio-temporal gait characteristics did not differ between the beginning and the end of exercise. Gait variability of the double-support time increased at the end as measured by both SD (P = 0.037) and CV (P = 0.030) but no change was observed for other variables. Left-right symmetry measured using either SI or SA did not differ between sessions. In summary, spatio-temporal gait characteristics and symmetry while wearing firefighting equipment are insensitive to physiological fatigue. Prolonged walking in heat while wearing firefighting equipment may increase gait variability and therefore the likelihood of a fall. Future studies are needed to confirm the potential relationship between fatigue and gait variability and to investigate the possible influence of individual variation

Reliability Analysis Approach For Operations Planning Of Hydropower Systems

Many existing hydropower storage facilities were built decades ago and components of these aging infrastructure facilities have higher risk of failure. Insufficient capacity or forced outages of the spillway and other waterway passage facilities during flooding incident could potentially increase the probability of dam safety incidents leading to public safety concerns. Currently approaches used to assess the risk and uncertainty in operational decision making are mainly based on qualitative assessment and expert judgment and can be significantly improved by the development of a framework that formally incorporates both qualitative and quantitative reliability analysis methods. Event tree analysis and fault tree analysis have traditionally been used in dam safety risk analysis, with results subject to data adequacy and availability. Our research shows that other methods, such as nonparametric analysis and Monte Carlo simulation techniques can yield good results as well. This study investigated the application of reliability analysis methods to existing hydropower storage facilities, with the objective of developing a new systems engineering based approach for risk and uncertainty analysis to assess and manage the risks of hydropower system operations. Our approach integrates reliability-based methods with hydro system optimization modeling to develop an operational reliability-based modeling framework and to formally treat risk and uncertainty in operations planning. This approach incorporates different sources of uncertainty that are typically encountered in operations planning of these systems, including failure probability of hydro system components such as non-power release structures and turbine facilities. This paper presents the framework we have developed and illustrates the application of our investigation for a hydropower system facility in British Columbia, Canada

A Multi-Objective Optimization Model For Operations Planning Of Multi-Reservoir Systems

This paper presents the development and evaluation of a multi-objective linear programming (LP) optimization tool for an operations planning platform (OPP). The LP optimization model is coded using a high level programming language called AMPL (A Mathematical Programming Language) and solved using a solver called CPLEX. This model was developed by closely working with operations planning engineers at BC Hydro, in Canada, with the support of a research team from the University of British Columbia. The optimization model incorporates two objectives to optimize the operation of a multi reservoir system: maximize revenue from power generation, and to minimize penalties resulting from deviations of reservoir elevations and spill releases from a preferred operating regime. Several multi-objective optimization techniques are being investigated including traditional methods such as the Weighting Method and the Constraint Method, as well as Goal Programming (GP) techniques. These methods would be tested for optimality and computational efficiency and would be generalized and used to study a number of multi-reservoir systems in British Columbia. Stochastic inflows would be considered in the model making use of chance-constraints and probability distribution functions based on historical inflow records. The model also incorporates features which simulate maintenance outages on hydropower plants. The goal is to determine the optimal maintenance schedules that minimize the cost of these outages. We present results of a case study to illustrate the capabilities of the model to provide decision makers with timely information on trade-off between different objectives. Maintenance schedules of generating units with and without optimization are also considered

Use of implantable cardioverter-defibrillators for primary prevention in older patients: A systematic literature review and meta-analysis

Background: Randomized clinical trials (RCTs) have demonstrated the efficacy of implantable cardioverter-defibrillators (ICDs) in reducing sudden cardiac death (SCD) in specific patient populations. However, patients ≥ 65 years were under-represented in these trials and the overall benefit of ICDs may be diminished in older patients due to competing risks for death. We evaluate the published data on ICD efficacy at reducing all-cause mortality in patients ≥ 65 years and in patients ≥ 75 years. Methods: We searched MEDLINE to identify RCTs and observational studies of ICDs that provided age-based outcome data for primary prevention of SCD. The primary endpoint was mortality evaluated by a meta-analysis of the RCTs using a random-effects model. Secondary endpoints included operative mortality, long-term complications and quality of life. Results: The enrollment of patients ≥ 65 years in RCTs was limited (range: 33% in DEFINITE to 56% in MUSTT). Combining data from four RCTs (n = 3,562) revealed that primary prevention ICD therapy is efficacious in reducing all-cause mortality in patients ≥ 65 years (HR 0.66; 95% CI 0.50–0.87; test of heterogeneity: X2 = 5.26; p = 0.15). For patients ≥ 75 years, combining data from four RCTs (n = 579) revealed that primary prevention ICD therapy remains efficacious in reducing all-cause mortality (HR 0.73; 95% CI 0.51–0.974; p = 0.03). There appears to be no difference in ICD-related, operative, in-hospital, or long- -term complications among older patients compared to younger patients, although it remains unclear if older patients have a better quality of life with an ICD than younger patients. Conclusions: Although the overall evidence regarding ICD efficacy in patients ≥ 65 years is limited and divergent, and the evidence available for patients ≥ 75 years is even more sparse, our meta-analysis suggests that primary prevention ICDs may be beneficial in older patients. Our findings need to be validated by future studies, particularly ones examining ICD complications and quality of life. (Cardiol J 2011; 18, 5: 503–514

Zastosowanie wszczepialnych kardiowerterów- -defibrylatorów w profilaktyce pierwotnej u pacjentów w podeszłym wieku. Systematyczny przegląd piśmiennictwa i metaanaliza

Wstęp: W randomizowanych badaniach klinicznych (RCT) wykazano skuteczność zastosowania wszczepialnych kardiowerterów-defibrylatorów (ICD) w zapobieganiu nagłym zgonom sercowym (SCD) w określonych grupach chorych. Jednak w badaniach tych oceniano niewielkie grupy chorych ≥ 65. roku życia, a całkowite korzyści z wszczepienia ICD wśród starszych pacjentów mogą być ograniczone ze względu na zwiększone ryzyko zgonu. Na podstawie aktualnego piśmiennictwa oceniono, na ile wszczepienie ICD zmniejsza ryzyko zgonu z jakiejkolwiek przyczyny u pacjentów ≥ 65. roku życia oraz w wieku ≥ 75 lat. Metody: Danych z RCT oraz badań obserwacyjnych oceniających profilaktykę pierwotną SCD, w zależności od wieku, poszukiwano w bazie MEDLINE. Za pierwszorzędowy punkt końcowy przyjęto śmiertelność ocenianą w metaanalizach lub RCT z zastosowaniem modelu ″random-effects″. Za drugorzędowe punkty końcowe przyjęto śmiertelność związaną z zabiegiem operacyjnym, powikłania odległe oraz jakość życia (QoL). Wyniki: Do RCT nie włączano zbyt licznych grup pacjentów ≥ 65. roku życia (od 33% badanej populacji w badaniu DEFINITE do 56% w badaniu MUSTT). Na podstawie zsumowanych danych z 4 RCT (n = 3562) wykazano, że wszczepienie ICD w profilaktyce pierwotnej skutecznie zapobiega śmiertelności całkowitej u chorych w wieku ≥ 65 lat [współczynnik hazardu (HR): 0,66; 95% przedział ufności (CI): 0,50–0,87; test niejednorodności X2 = 5,26; p = 0,15). U pacjentów ≥ 75. roku życia zsumowane dane z 4 badań RCT (n = 579) również potwierdziły skuteczność ICD w profilaktyce pierwotnej w zapobieganiu śmiertelności całkowitej (HR: 0,73; 95% CI: 0,51–0,974; p = 0,03). Wydaje się, że powikłania związane z ICD, z zabiegiem operacyjnym, wewnątrzszpitalne oraz odległe nie różnią się istotnie w grupach pacjentów w podeszłym wieku w porównaniu z młodszymi chorymi, jednak pozostaje niejasne, czy u starszych osób wszczepienie ICD poprawia jakość życia bardziej niż u młodszych chorych. Wnioski: Choć dane dotyczące skuteczności ICD u pacjentów ≥65. roku życia są ograniczone i rozbieżne, a dostępne informacje na temat chorych w wieku ≥ 75 lat — jeszcze bardziej niepełne, wyniki niniejszej metaanalizy sugerują, że pacjenci w podeszłym wieku mogą odnieść korzyści z wszczepienia ICD w ramach profilaktyki pierwotnej. Rezultaty autorów metaanalizy powinny zostać zweryfikowane w kolejnych badaniach, zwłaszcza oceniających powikłania związane z ICD oraz jakość życia

Remodelling of human atrial K+ currents but not ion channel expression by chronic β-blockade

Chronic β-adrenoceptor antagonist (β-blocker) treatment in patients is associated with a potentially anti-arrhythmic prolongation of the atrial action potential duration (APD), which may involve remodelling of repolarising K+ currents. The aim of this study was to investigate the effects of chronic β-blockade on transient outward, sustained and inward rectifier K+ currents (ITO, IKSUS and IK1) in human atrial myocytes and on the expression of underlying ion channel subunits. Ion currents were recorded from human right atrial isolated myocytes using the whole-cell-patch clamp technique. Tissue mRNA and protein levels were measured using real time RT-PCR and Western blotting. Chronic β-blockade was associated with a 41% reduction in ITO density: 9.3 ± 0.8 (30 myocytes, 15 patients) vs 15.7 ± 1.1 pA/pF (32, 14), p < 0.05; without affecting its voltage-, time- or rate dependence. IK1 was reduced by 34% at −120 mV (p < 0.05). Neither IKSUS, nor its increase by acute β-stimulation with isoprenaline, was affected by chronic β-blockade. Mathematical modelling suggested that the combination of ITO- and IK1-decrease could result in a 28% increase in APD90. Chronic β-blockade did not alter mRNA or protein expression of the ITO pore-forming subunit, Kv4.3, or mRNA expression of the accessory subunits KChIP2, KChAP, Kvβ1, Kvβ2 or frequenin. There was no reduction in mRNA expression of Kir2.1 or TWIK to account for the reduction in IK1. A reduction in atrial ITO and IK1 associated with chronic β-blocker treatment in patients may contribute to the associated action potential prolongation, and this cannot be explained by a reduction in expression of associated ion channel subunits

Morphological characteristics of motor neurons do not determine their relative susceptibility to degeneration in a mouse model of severe spinal muscular atrophy

Spinal muscular atrophy (SMA) is a leading genetic cause of infant mortality, resulting primarily from the degeneration and loss of lower motor neurons. Studies using mouse models of SMA have revealed widespread heterogeneity in the susceptibility of individual motor neurons to neurodegeneration, but the underlying reasons remain unclear. Data from related motor neuron diseases, such as amyotrophic lateral sclerosis (ALS), suggest that morphological properties of motor neurons may regulate susceptibility: in ALS larger motor units innervating fast-twitch muscles degenerate first. We therefore set out to determine whether intrinsic morphological characteristics of motor neurons influenced their relative vulnerability to SMA. Motor neuron vulnerability was mapped across 10 muscle groups in SMA mice. Neither the position of the muscle in the body, nor the fibre type of the muscle innervated, influenced susceptibility. Morphological properties of vulnerable and disease-resistant motor neurons were then determined from single motor units reconstructed in Thy.1-YFP-H mice. None of the parameters we investigated in healthy young adult mice - including motor unit size, motor unit arbor length, branching patterns, motor endplate size, developmental pruning and numbers of terminal Schwann cells at neuromuscular junctions - correlated with vulnerability. We conclude that morphological characteristics of motor neurons are not a major determinant of disease-susceptibility in SMA, in stark contrast to related forms of motor neuron disease such as ALS. This suggests that subtle molecular differences between motor neurons, or extrinsic factors arising from other cell types, are more likely to determine relative susceptibility in SMA

Caspase-independence and characterization of bisnaphthalimidopropyl spermidine induced cytotoxicity in HL60 cells

The authors wish to thank Viv Buchan of the Rowett Institute Analytical Division for polyamine analysis and gratefully acknowledges the Robert Gordon University (PKTL, LC, CSB, SJD), The Scottish Government (Rural and Environment Science and Analytical Services [RESAS] Division; CSB, SJD, LM) and the Royal Society of Chemistry (PKTL) for financial support.Peer reviewedPostprin

Bacterial Causes of Empyema in Children, Australia, 2007–2009

Most infections were caused by non–7-valent pneumococcal conjugate vaccine serotypes