87,698 results

  • Honey as a topical treatment for wounds

    Jull, Andrew; Rodgers, Anthony; Greenaway, Natalie (2008)

    Journal article
    The University of Auckland Library

    Background Honey is a viscous, supersaturated sugar solution derived from nectar gathered and modified by the honeybee, Apis mellifera. Honey has been used since ancient times as a remedy in wound care. Evidence from animal studies and some trials has suggested honey may accelerate wound healing. Objectives The objective was to determine whether honey increases the rate of healing in acute wounds (burns, lacerations and other traumatic wounds) and chronic wounds (venous ulcers, arterial ulcers, diabetic ulcers, pressure ulcers, infected surgical wounds). Search strategy We searched the Cochrane Wounds Group Specialised Register (May 2008), CENTRAL (May 2008) and several other electronic databases (May 2008). Bibliographies were searched and manufacturers of dressing products were contacted for unpublished trials. Selection criteria Randomised and quasi randomised trials that evaluated honey as a treatment for any sort of acute or chronic wound were sought. There was no restriction in terms of source, date of publication or language. Wound healing was the primary endpoint. Data collection and analysis Data from eligible trials were extracted and summarised using a data extraction sheet by one author and independently verified by a second author. Main results 19 trials (n=2554) were identified that met the inclusion criteria. In acute wounds, three trials evaluated the effect of honey in acute lacerations, abrasions or minor surgical wounds and nine trials evaluated the effect the honey in burns. In chronic wounds two trials evaluated the effect of honey in venous leg ulcers and one trial in pressure ulcers, infected post-operative wounds, and Fournier's gangrene respectively. Two trials recruited people with mixed groups of chronic or acute wounds. The poor quality of most of the trial reports means the results should be interpreted with caution, except in venous leg ulcers. In acute wounds, honey may reduce time to healing compared with some conventional dressings in partial thickness burns (WMD -4.68 days, 95%CI -4.28 to -5.09 days). All the included burns trials have originated from a single centre, which may have impact on replicability. In chronic wounds, honey in addition to compression bandaging does not significantly increase healing in venous leg ulcers (RR 1.15, 95%CI 0.96 to 1.38). There is insufficient evidence to determine the effect of honey compared with other treatments for burns or in other acute or chronic wound types.

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  • Responsiveness of generic and disease-specific health-related quality of life instruments to venous ulcer healing

    Jull, Andrew; Parag, Varsha; Greenaway, Natalie; Rodgers, Anthony (2010)

    Journal article
    The University of Auckland Library

    The aim of the study was to evaluate the responsiveness of the Short Form Health Survey, the EuroQol 5 Dimension questionnaire, and the Charing Cross Venous Ulcer Questionnaire (CXVUQ) to venous ulcer healing. Participants had health-related quality of life measured at baseline and 12 weeks. Standardized response means were calculated to assess the responsiveness of the instruments to change in an ulcer state (healed vs. unhealed). Three hundred and sixty-eight participants completed the questionnaires at baseline and 360 at 12 weeks. One hundred and ninety-three participants (54%) had healed at 12 weeks. The standardized response means ranged from -0.01 to 0.47 for Short Form Health Survey, 0.10-0.31 for EuroQol 5 Dimension questionnaire, and -0.21 to -0.92 for CXVUQ. Differences between healed and unhealed participants at 12 weeks were significantly different for three of the eight domains on Short Form Health Survey and on all domains for the CXVUQ. There were no significant differences between the groups on the EuroQol 5 Dimension questionnaire scales. CXVUQ was more responsive than the generic instruments to change in ulcer status over 12 weeks for measuring health-related quality of life of patients with venous ulceration.

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  • Transitions to palliative care in acute hospitals in England: qualitative study

    Gott, Caryl; Ingleton, C; Bennett, MI; Gardiner, Clare (2011-03-29)

    Journal article
    The University of Auckland Library

    Objective To explore how transitions to a palliative care approach are perceived to be managed in acute hospital settings in England. Design Qualitative study. Setting Secondary or primary care settings in two contrasting areas of England. Participants 58 health professionals involved in the provision of palliative care in secondary or primary care. Results Participants identified that a structured transition to a palliative care approach of the type advocated in UK policy guidance is seldom evident in acute hospital settings. In particular they reported that prognosis is not routinely discussed with inpatients. Achieving consensus among the clinical team about transition to palliative care was seen as fundamental to the transition being effected; however, this was thought to be insufficiently achieved in practice. Secondary care professionals reported that discussions about adopting a palliative care approach to patient management were not often held with patients; primary care professionals confirmed that patients were often discharged from hospital with ???false hope??? of cure because this information had not been conveyed. Key barriers to ensuring a smooth transition to palliative care included the difficulty of ???standing back??? in an acute hospital situation, professional hierarchies that limited the ability of junior medical and nursing staff to input into decisions on care, and poor communication. Conclusion Significant barriers to implementing a policy of structured transitions to palliative care in acute hospitals were identified by health professionals in both primary and secondary care. These need to be addressed if current UK policy on management of palliative care in acute hospitals is to be established.

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  • The PREPARE pilot RCT of home-based progressive resistance exercises for venous leg ulcers

    Jull, A; Parag, Varsha; Greenaway, Natalie; Maddison, Ralph; Kerse, Ngaire; Johns, T (2009)

    Journal article
    The University of Auckland Library

    Objective: To establish the feasibility of conducting a home-based progressive resistance exercise programme to improve calf muscle pump function in community-based patients with venous leg ulcers. Method: Participants randomised to receive a 12-week progressive resistance exercise programme using heel raises in addition to compression. The control was usual care in addition to compression. Randomisation was stratified by ulcer duration and ulcer size. Air plethysmography was used to determine changes in calf muscle pump function from baseline. Changes in ulcer parameters were measured using the SilhouetteMobile device. Results: Forty participants were randomised. There were significantly greater improvements in ejection fraction of the calf muscle in the exercise group compared to the control group (mean difference 18.5%, 95%CI 0.03 to 36.6%, p<0.05). Other parameters improved in the exercise group but the mean differences were not significant. Adherence with prescribed exercises was 81% and there was no significant difference in the numbers reporting adverse events. There were no significant differences on ulcer healing parameters (change in area, percentage change in area, proportion healed at 12 weeks, time to healing). Conclusion: A community-based randomised trial of progressive resistance exercise is feasible. The prescribed exercises appeared to increase ejection fraction, but the effect of exercise on ulcer healing requires further investigation.

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  • Developing biosafety risk hypotheses for invertebrates exposed to GM plants using conceptual food webs: a case study with elevated triacylglyceride levels in ryegrass.

    Malone, LA; Barratt, BIP; Todd, JH; Burgess, EPJ (2011)

    Journal article
    The University of Auckland Library

    Regulators are acutely aware of the need for meaningful risk assessments to support decisions on the safety of GM crops to non-target invertebrates in determining their suitability for field release. We describe a process for developing appropriate, testable risk hypotheses for invertebrates in agroecosystems that might be exposed to plants developed by GM and future novel technologies. An existing model (PRONTI) generates a ranked list of invertebrate species for biosafety testing by accessing a database of biological, ecological and food web information about species which occur in cropping environments and their potential interactions with a particular stressor (Eco Invertebase). Our objective in this contribution is to explore and further utilise these resources to assist in the process of problem formulation by identifying potentially significant effects of the stressor on the invertebrate community and the ecosystem services they provide. We propose that for high ranking species, a conceptual food web using information in Eco Invertebase is constructed, and using an accepted regulatory risk analysis framework, the likelihood of risk, and magnitude of impact for each link in the food web is evaluated. Using as filters only those risks evaluated as likely to extremely likely, and the magnitude of an effect being considered as moderate to massive, the most significant potential effects can be identified. A stepwise approach is suggested to develop a sequence of appropriate tests. The GM ryegrass plant used as the “stressor” in this study has been modified to increase triacylglyceride levels in foliage by 100% to increase the metabolisable energy content of forage for grazing animals. The high-ranking “test” species chosen to illustrate the concept are New Zealand native species Wiseana cervinata (Walker) (Lepidoptera: Hepialidae), Persectania aversa (Walker) (Lepidoptera: Noctuidae), and the self-introduced grey field slug, Deroceras reticulatum (Müller).

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  • Automated imaging of extended tissue volumes using confocal microscopy.

    Sands, GB; Gerneke, Dane; Hooks, Darren; Green, CR; Smaill, Bruce; Le Grice, Ian (2005)

    Journal article
    The University of Auckland Library

    Confocal microscopy enables constitutive elements of cells and tissues to be viewed at high resolution and reconstructed in three dimensions, but is constrained by the limited extent of the volumes that can be imaged. We have developed an automated technique that enables serial confocal images to be acquired over large tissue areas and volumes. The computer-controlled system, which integrates a confocal microscope and an ultramill using a high-precision translation stage, inherently preserves specimen registration, and the user control interface enables ???exible speci???cation of imaging protocols over a wide range of scales and resolutions. With this system it is possible to reconstruct speci???ed morphological features in three dimensions and locate them accurately throughout a tissue sample. We have successfully imaged various samples at 1-lm voxel resolution on volumes up to 4 mm 3 and on areas up to 75 mm 2 . Used in conjunction with appropriate embedding media and immuno-histochemical probes, the techniques described in this paper make it possible to routinely map the distributions of key intracellular structures over much larger tissue domains than has been easily achievable in the past.

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  • Microscopic imaging of extended tissue volumes

    Le Grice, IJ; Sands, Gregory; Hooks, Darren; Gerneke, Dane; Smaill, Bruce (2004)

    Journal article
    The University of Auckland Library

    1. Detailed information about three-dimensional structure is key to understanding biological function. 2. Confocal laser microscopy has made it possible to reconstruct three-dimensional organization with exquisite resolution at cellular and subcellular levels. 3. There have been few attempts to acquire large image volumes using the confocal laser scanning microscope. 4. Previously, we have used manual techniques to construct extended volumes (several mm in extent, at 1.5 m voxel size) of myocardial tissue. 5. We are now developing equipment and ef???cient automated methods for acquiring extended morphometric databases using confocal laser scanning microscopy

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  • Surface imaging microscopy using an ultramiller for large volume 3D reconstruction of wax- and resin-embedded tissues

    Gerneke, Dane; Sands, Gregory; Ganesalingam, Ramanujan; Joshi, P; Caldwell, Bryan; Smaill, Bruce; Le Grice, Ian (2007-10)

    Journal article
    The University of Auckland Library

    Three-dimensional reconstruction of large tissue volumes using histological thin sections poses difficulties because of registration of sections, section distortion, and the possibility of incomplete data set collection due to section loss. We have constructed an integrated surface imaging system that successfully addresses these problems. Embedded tissue is mounted on a high precision XYZ stage and the upper surface is iteratively: (i) stained to provide an effective optical section, (ii) imaged using a digital camera, and (iii) removed with an ultramiller. This approach provides for the reconstruction of high-quality 31) images by inherently preserving image registration, eliminates section distortion, thus removing the need for complex realignment and correction, and also ensures full capture of all image planes. The system has the capacity to acquire images of tissue structure with voxel sizes from 0.5 to 50 mu m over dimensions ranging from micrometers to tens of millimeters. The ultramiller enables large samples to be imaged by reliably removing tissue over their full extent. The ability to visualize key features of 3D tissue structure across such a range of scale and resolution will facilitate the development of a greater understanding of the relationship between structure and function. This understanding is essential for better analyses of the structural changes associated with different disease states, and the development of structure-based computer models of biological function.

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  • Automated extended volume imaging of tissue using confocal and optical microscopy.

    Sands, Gregory; Gerneke, Dane; Smaill, Bruce; Le Grice, Ian (2006-01)

    Conference item
    The University of Auckland Library

    Conventional histologic techniques cannot readily be used for 3D reconstruction of large tissue volumes. We have developed an imaging rig which supports both confocal and light microscopy, and utilizes a surface imaging approach to serially image embedded tissue blocks while maintaining alignment and registration of the image series.

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  • Stress as an index of metabolic cost in papillary muscle of the cat

    Gibbs, CL; Loiselle, Denis (1979)

    Journal article
    The University of Auckland Library

    Active stress, stress-time integral (STI) and total heat production of cat right ventricular papillary muscles were recorded during brief trains of isometric twitch contractions at muscle lengths less than or equal to optimal length. Individual muscles were subjected to a 10 degree C change in temperature, a change of stimulus frequency and the addition of isoprenaline sulphate (10(-7) mol. 1(-1). The STI-heat and stress-heat data were subjected respectively to linear and quadratic regression analyses. For both relations, the intercept (stress-independent heat) was unaffected by the frequency change, doubled by the temperature decrease and trebled by the addition of isoprenaline. None of the treatments had a significant effect on the first or second order coefficients of the stress-heat relation. The slope of the STI-heat relation was halved by lowering the temperature, increased 50% by the addition of isoprenaline and unaffected by stimulus frequency. Thus the energetic cost of a given stress increment was constant across conditions while that for a given STI increment was not. Stress is the better mechanical index of myocardial energy cost when the inotropic state is changing.

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  • Stretch-induced increase in resting metabolism of isolated papillary muscle

    Loiselle, Denis (1982)

    Journal article
    The University of Auckland Library

    A mathematical model of oxygen diffusion into quiescent papillary muscles in vitro is developed. The model incorporates a continuous sigmoidal function relating the rate of oxygen consumption and the partial pressure of oxygen within the tissue. The behavior of the model is explored over a wide range of external oxygen partial pressures, oxygen consumption/partial pressure relations, oxygen diffusivities, muscle dimensions, and resting metabolic rates, while the muscle is subjected to simulated stretches of various extents in order to test the assertion that the stretch-induced increase in basal metabolic rate observed experimentally implies the existence of an anoxic core region of papillary muscles in vitro. The model predicts the existence of an oxygen diffusion-mediated stretch response of resting papillary muscle metabolism, but one which is quantitatively insignificant compared with experimentally observed values. The classic Hill diffusion model, which explicitly predicts an anoxic core, likewise predicts stretch effects of magnitudes smaller than those frequently observed. It is concluded that the increment in basal metabolism of papillary muscles subjected to stretch in vitro cannot be taken as evidence of oxygen diffusion limitation in unstretched preparations.

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  • The efficiency of muscle contraction

    Smith, Nicolas; Barclay, Christopher; Loiselle, Denis (2005)

    Journal article
    The University of Auckland Library

    When a muscle contracts and shortens against a load, it performs work. The performance of work is fuelled by the expenditure of metabolic energy, more properly quanti???ed as enthalpy (i.e., heat plus work). The ratio of work performed to enthalpy produced provides one measure of ef???ciency. However, if the primary interest is in the ef???ciency of the actomyosin cross-bridges, then the metabolic overheads associated with basal metabolism and excitation???contraction coupling, together with those of subsequent metabolic recovery process, must be subtracted from the total heat and work observed. By comparing the cross-bridge work component of the remainder to the Gibbs free energy of hydrolysis of ATP, a measure of thermodynamic ef???ciency is achieved. We describe and quantify this partitioning process, providing estimates of the ef???ciencies of selected steps, while discussing the errors that can arise in the process of quanti???cation. The dependence of ef???ciency on animal species, ???bre-type, temperature, and contractile velocity is considered. The effect of contractile velocity on energetics is further examined using a two-state, Huxley-style, mathematical model of cross-bridge cycling that incorporates ???lament compliance. Simulations suggest only a modest effect of ???lament compliance on peak ef???ciency, but progressively larger gains (vis-a-vis the rigid ???lament case) as contractile velocity approaches " Vmax: This effect is attributed primarily to a reduction in the component of energy loss arising from detachment of cross-bridge heads at non-zero strain.

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  • Trabeculae carneae as models of the ventricular walls: implications for the delivery of oxygen

    Goo, SY; Joshi, P; Sands, Gregory; Gerneke, DA; Taberner, Andrew; Dollie, Q; Le Grice, Ian; Loiselle, Denis (2009)

    Journal article
    The University of Auckland Library

    Trabeculae carneae are the smallest naturally arising collections of linearly arranged myocytes in the heart. They are the preparation of choice for studies of function of intact myocardium in vitro. In vivo, trabeculae are unique in receiving oxygen from two independent sources: the coronary circulation and the surrounding ventricular blood. Because oxygen partial pressure (PO2) in the coronary arterioles is identical in specimens from both ventricles, whereas that of ventricular blood is 2.5-fold higher in the left ventricle than in the right ventricle, trabeculae represent a ???natural laboratory??? in which to examine the influence of ???extravascular??? PO2 on the extent of capillarization of myocardial tissue. We exploit this advantage to test four hypotheses. (1) In trabeculae from either ventricle, a peripheral annulus of cells is devoid of capillaries. (2) Hence, sufficiently small trabeculae from either ventricle are totally devoid of capillaries. (3) The capillary-to-myocyte ratios in specimens from either ventricle are identical to those of their respective walls. (4) Capillary-to-myocyte ratios are comparable in specimens from either ventricle, reflecting equivalent energy demands in vivo, driven by identical contractile frequencies and comparable wall stresses. We applied confocal fluorescent imaging to trabeculae in cross section, subsequently using semi-automated segmentation techniques to distinguish capillaries from myocytes. We quantified the capillary-to-myocyte ratios of trabeculae from both ventricles and compared them to those determined for the ventricular free walls and septum. Quantitative interpretation was furthered by mathematical modeling, using both the classical solution to the diffusion equation for elliptical cross sections, and a novel approach applicable to cross sections of arbitrary shape containing arbitrary disposition of capillaries and non-respiring collagen cords.

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  • The surface of the heart leaks oxygen

    Loiselle, Denis; van Beek, JHGM; Mawson, DA; Hunter, Peter (1995)

    Journal article
    The University of Auckland Library

    The rate of oxygen consumption of the heart is classically measured using the Fick principle. Uncritical application of this principle can cause errors of measurement, particularly when estimating cardiac basal metabolic rate. Consideration of these errors leads to a model that supports modern notions of oxygen exchange in perfused tissue.

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  • The effect of hyperosmolality on the rate of heat production of quiescent trabeculae isolated from the rat heart

    Loiselle, Denis; Stienen, GJM; vanHardeveld, C; vanderMeulen, ET; Zahalak, GI; Daut, J; Elzinga, G (1996)

    Journal article
    The University of Auckland Library

    We have measured the rate of heat production of isolated, quiescent, right ventricular trabeculae of the rat under isosmotic and hyperosmotic conditions, using a microcalorimetric technique. In parallel experiments, we measured force production and i

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  • Stress development, heat production and dynamic modulus of rat isolated cardiac trabeculae revealed in a flow-through micro-mechano-calorimeter

    Taberner, AJ; Han, June; Kirton, Robert; Loiselle, Denis; Nielsen, Poul (2010)

    Conference item
    The University of Auckland Library

    Progress toward understanding the thermo-mechanical behavior of isolated cardiac muscle, excised from either healthy or diseased heart, is contingent on being able to measure simultaneously the stress (force per cross- sectional area) and heat production. Determination of dynamic modulus (dynamic stiffness times muscle length per cross- sectional area) sheds further light on the behavior of the force- and heat-generating actin-myosin cross-bridges. We are in a unique position to perform such measurements, given the recent completion of a micro-mechano-calorimeter. In this paper, we characterize the micro-mechano-calorimeter and present experimental results of twitch stress, heat per twitch and dynamic modulus measured in rat right-ventricular trabeculae at varied stimulus frequencies and muscle lengths. The minute radial dimensions of cardiac trabeculae (which approximate those of a human hair) ensure adequate provision of oxygen and nutrients via diffusion from the continuously replenished superfusate flowing through the measurement chamber. This enables investigation of the thermo-mechanical performance of cardiac trabeculae for many hours.

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  • Simultaneous heat and fluorescence changes in cardiac muscle at high rates of energy expenditure: effects of caffeine and isoprenaline

    Chapman, John; Gibbs, CL; Loiselle, Denis (1977)

    Journal article
    The University of Auckland Library

    The relationship between the fluorescence-time integral and heat production was investigated in isolated rabbit papillary muscles at room temperature. Four treatments were used: (1) control; (2) 10???3 m caffeine; (3) 5??10???3m caffeine; (4) 5??10???3 m caffeine +2??10???7m isoprenaline. The first two treatments were associated with low rates of energy expenditure for a given rate of stimulation whereas high rates of energy turnover occurred with the last two treatments. The enthalpy versus load relationship was studied in each treatment as a means for obtaining plots of fluorescence-time integral versus active heat production. All the plots showed high correlations between the two parameters but the linearity of the relationship broke down at high rates of energy expenditure, associated with treatments (3) and (4), as complexities arose in the fluorescence waveforms. No significant changes in resting heat production were induced by any of the drug treatments. Although the mechanical work output was much higher in treatments (3) and (4), the associated extra-active heat production was sufficient to cause a marked drop in mechanical efficiency. Possible biochemical mechanisms underlying the results are discussed.

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  • Species differences in cardiac energetics

    Loiselle, Denis; Gibbs, CL (1979)

    Journal article
    The University of Auckland Library

    The energy flux of rat, guinea pig, and cat papillary muscles was measured myothermically under resting, isometric, and isotonic conditions at 27 degrees C. Resting heat rate was highest in the smallest species and declined with body size. The slope of the isometric heat-stress relationship was constant across species, whereas the stress-independent heat component was least for rat muscles. The shape of the load enthalpy relationship was similar across species. Maximum mechanical efficiency, work-enthalpy, occurred with lighter loads than for skeletal muscle (approximately 0.2 Po). Rat muscle had the smallest enthalpy per beat and the highest active mechanical efficiency, but this advantage was nullified by the higher basal heat rate. The myothermic data are compared with cardiac oxygen consumption values in the literature and it is concluded, contrary to the deductions of common dimensional arguments, that cardiac energy expenditure across species is not directly proportional to heart rate. Reasons for this discrepancy are considered together with the likely contribution of cardiac metabolism (EH) to total body metabolism (EB). It seems likely that smaller species have lower EH/EB.

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  • Species-independent metabolic response to an increase of [Ca2+](i) in quiescent cardiac muscle

    Ward, Marie-Louise; Cooper, PJ; Hanley, PJ; Loiselle, DS (2003)

    Journal article
    The University of Auckland Library

    1. The aim of the present investigation was to contrast the Ca2+ dependence of cardiac energy metabolism in two species with differential reliance on extracellular Ca2+ for excitation-contraction coupling. 2. We measured energy expenditure as the rat

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  • Role of extracellular [Ca2+] in fatigue of isolated mammalian skeletal muscle

    Cairns, Simeon; Hing, WA; Slack, John; Mills, RG; Loiselle, Denis (1998)

    Journal article
    The University of Auckland Library

    The possible role of altered extracellular Ca2+ concentration ([Ca2+](o)) in skeletal muscle fatigue was tested on isolated slow-twitch soleus and fast-twitch extensor digitorum longus muscles of the mouse. The following findings were made. 1) A chan

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