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At least 19 recordsLinked to original sources

PubMed2003

Simultaneous multisite endocardial mapping of sustained and non-sustained atrial fibrillation in humans.

The aim of this study was to investigate the differences between sustained and non-sustained forms of human atrial fibrillation (AF) using multielectrode endocardial recordings. Methods. Sixty-four pole basket catheters were deployed in the right atrium (RA) of 3 groups of patients: 1) patients with persistent AF (> 48 hours); 2) induced sustained AF (> 15 minutes); and 3) induced non-sustained AF (< 15 minutes). Beat to beat AF intervals (FF) were evaluated for each bipole. On the basis of signal characteristics and direction of wavefront propagation, the degree of spatial and temporal organization of AF was assessed. Results. Persistent AF showed the shortest FF intervals (161 ms) and lowest overall degree of AF organization, induced non-sustained AF the longest FF intervals (192 ms) and highest degree of organization. FF intervals of induced sustained AF were only slightly longer (169 ms) compared to persistent AF. Within each AF group, the lateral wall showed the highest degree of organization, the septal region the lowest. Conclusion. In humans, FF interval and overall degree of AF organization were found to increase significantly from sustained to non-sustained AF. Persistent and induced sustained AF, however, only slightly differed in these parameters.

Adult↗

PubMed2004

Pharmacokinetic study on lovastatin sustained-release tablet and sustained-release capsule in Beagal dogs.

This study pharmacokinetically examined the lovastatin sustained-release tablet and sustained-release capsule in Beagle dogs. An reversed-phase HPLC method was established for the determination of lovastatin in Beagle dog plasma. Pharmacokinetic findings were compared among three preparation(lovastatin sustained-release tablet, Tp; sustained-release capsule, TJ and conventional capsule). Our results showed that the pharmacokinetic parameters in 6 dogs after single-dose oral administration of three perparations were calculated. Tmax, Cmax and MRT revealed significant difference (P<0.05). Relative bioavailability was 111.5 +/- 16.9% (Tp) and 110.4% +/- 9.6% (Tj). The pharmacokinetic parameters in the 6 dogs after multiple-dose oral administration of three perparations, Tmax, Cmax MRT and DF had significant difference (P < 0.05); Cav, Cmin and AUC0-24 h displayed no significant difference (P>0.05). It is concluded that the lovastatin sustained-release tablet and sustained-release capsule are able to maintain a sustained-release for 24 h.

Animals↗

PubMed1999

Implantable defibrillator event rates in patients with unexplained syncope and inducible sustained ventricular tachyarrhythmias: a comparison with patients known to have sustained ventricular tachycardia.

OBJECTIVES: To assess the clinical significance of inducible ventricular tachyarrhythmias among patients with unexplained syncope. BACKGROUND: Induction of sustained ventricular arrhythmias at electrophysiology study in patients with unexplained syncope and structural heart disease is usually assigned diagnostic significance. However, the true frequency of subsequent spontaneous ventricular tachyarrhythmias in the absence of antiarrhythmic medications is unknown. METHODS: In a retrospective case-control study, the incidence of implantable cardiac defibrillator (ICD) therapies for sustained ventricular arrhythmias among patients with unexplained syncope or near syncope (syncope group, n = 22) was compared with that of a control group of patients (n = 32) with clinically documented sustained ventricular tachycardia (VT). Sustained ventricular arrhythmias were inducible in both groups and neither group received antiarrhythmic medications. All ICDs had stored electrograms or RR intervals. Clinical variables were similar between groups except that congestive cardiac failure was more common in the syncope group. RESULTS: Kaplan-Meier analysis of the time to first appropriate ICD therapy for syncope and control groups produced overlapping curves (p = 0.9), with 57 +/- 11% and 50 +/- 9%, respectively, receiving ICD therapy by one year. In both groups, the induced arrhythmia was significantly faster than spontaneous arrhythmias, but the cycle lengths of induced and spontaneous arrhythmias were positively correlated (R = 0.6, p < 0.0001). During follow-up, three cardiac transplantations and seven deaths occurred in the syncope group, and two transplantations and five deaths occurred in the control group (36-month survival without transplant 52 +/- 11% and 83 +/- 7%, respectively, p = 0.03). CONCLUSIONS: In patients with unexplained syncope, structural heart disease and inducible sustained ventricular arrhythmias, spontaneous sustained ventricular arrhythmias occur commonly and at a similar rate to patients with documented sustained VT. Thus, electrophysiologic testing in unexplained syncope can identify those at risk of potentially life-threatening tachyarrhythmias, and aggressive treatment of these patients is warranted.

Aged↗

PubMed1999

Sustainable agriculture: how to sustain a production system in a changing environment.

During the past 10-15 years, sustainable agriculture has progressed from a focus primarily on a low-input, organic farming approach with a major emphasis on small fruit or vegetable production farms, often described as Low Input Sustainable Agriculture, to the current situation where sustainability is an important part of mainstream animal and plant production units. The US Department of Agriculture programmes cover a broad range of activities, including conserving the natural resource base, enhancing environmental quality, and sustaining productivity of the nation's farms. The use of Geographic Information Systems technology to direct application of fertilisers, pesticides, and herbicides is one example of a rapidly emerging technology that can reduce use of external inputs, protect the agricultural environment, and improve economic returns. This Geographic Information Systems technology also is being used to localise animal pest and disease problems, assist in regulatory or control measures, and identify high risk areas that might need different management systems or should be avoided as sites for animal production. Use of intensive grazing systems also has increased markedly over the past 5-6 years. These systems will allow longer grazing seasons in southern parts of the USA, provide more efficient use of the forages being produced and reduce labour costs in the typical dairy operation. Major animal and plant production agriculture-oriented programmes at the US Department of Agriculture focus on integrated production systems, use of Integrated Pest Management techniques, and development of alternative methods to manage pests and diseases that reduce or avoid the use of drugs and chemicals. The US Department of Agriculture has a programme for sustainable agriculture, the Sustainable Agriculture Research and Education programme, which emphasises alternative approaches for animal and plant production systems.

Agriculture↗

PubMed2005

Framing the elusive concept of sustainability: a sustainability hierarchy.

Usage of the word "sustainability" is widespread and incorporates a plethora of meanings. After reviewing four extant sustainability frameworks, we propose a Sustainability Hierarchy to structure a broad array of issues that have been associated with sustainability. These issues vary widely in their urgency, severity and uncertainty of consequences, and temporal and spatial dimensions. It categorizes actions some view as unsustainable based on their direct or indirect potential to (i) endanger the survival of humans; (ii) impair human health, (iii) cause species extinction or violate human rights; or (iv) reduce quality of life or have consequences that are inconsistent with other values, beliefs, or aesthetic preferences. Effects considered include impediments to the ecosystem functions that support human life, human health, and species viability. This paper argues that for sustainability to become a more meaningful concept, the many worthy issues in the fourth category (values, beliefs, and aesthetic preferences) should not be considered sustainability concerns. Implications for companies, policy makers, and scientists are discussed.

Animals↗

PubMed1993

Individuals who sustain nonosteoporotic fractures continue to also sustain fragility fractures.

This retrospective case control study was done in order to investigate whether patients who sustain a "nonosteoporotic fracture" early in life also continue to sustain fragility fractures later in life. All patients who had been treated at the Department of Orthopedics in Malmö with a tibial shaft fracture from 1949 to 1963 (n = 767) or an ankle fracture from 1961 to 1965 (n = 786) were included in this study. At the time of follow-up in 1992, 231 of the patients who sustained a tibial shaft fracture and 260 of the patients who sustained an ankle fracture were still living in the city of Malmö. Objective registration was done of all subsequent fractures that these former patients had sustained. Comparison was done with corresponding data from double numbers of age- and sex-matched controls who at that time (1950s and 1960s) had no such fractures. At the time of the fracture as well as today, the controls were living in the area of Malmö. Individuals with earlier tibial or ankle fractures had an increased incidence of fractures generally classified as fragility fractures. There was no difference in this respect between men and women, nor whether the initial fracture had been diaphyseal or metaphyseal. We conclude that sustenance of fractures early in life may serve as a predictor for fragility fractures later in life.

Adolescent↗

PubMed2005

Delivering sustainability therapy in sustainable development projects.

This paper explores the apparent contradiction between the 'linearity' of most Sustainable Development projects, with time-bound and defined outputs achieved at a fixed cost, and an implied 'circularity' of the theory whereby there is no 'end'. Projects usually have clear parameters within which they are implemented, and the inclusion of elements such as the need for accountability, measurable impact and 'value for money' have grown in importance. It could be argued that we live in a 'projectified' and therefore linear world. The paper explores the potential contradiction between 'linearity' and 'circularity', and suggests that one way around this is to frame the project within a form of the Kolb Learning Cycle heuristic. This will facilitate a rationalisation from those implementing the sustainable development project as to why decisions are being made and for whom. If these questions are opened up to the project stakeholders, including beneficiaries, then the Kolb cycle could encourage learning and understanding by all involved. It could also provide Sustainability Therapy to those trapped in processes, which they find orthogonal to their own perceptions. It is suggested that such learning, therapy and reflective practice should be a valid output of the sustainable development project, although typically the focus is only upon the final outputs and how they feed into policy. Ironically funders would be well advised to take a broader perspective in order to achieve true 'value for money' within such projects, even if learning is not an easily measurable or tangible outcome. These points are explored within the context of the wider literature and experience with a sustainable development project undertaken in Malta.

Conservation of Natural Resources↗

PubMed2006

Measuring sustained attention after traumatic brain injury: differences in key findings from the sustained attention to response task (SART).

Clinical reports after traumatic brain injury (TBI) suggest frequent difficulties with sustained attention, but their objective measurement has proved difficult. In 1997, Robertson and colleagues reported on a new sustained attention assessment tool, the sustained attention to response task (SART). Individuals with TBI were reported to produce more errors of commission on the SART than control participants, and both groups showed a relationship between SART errors and everyday lapses of attention as measured by the cognitive failures questionnaire (CFQ). Although few direct replications of these findings have been reported, the SART has been used widely as a measure of sustained attention in TBI, in normal controls, and in various other clinical samples. As part of a program of research on attention in TBI, we administered the SART and the CFQ to a sample of 34 survivors of moderate to severe TBI and to 35 control participants. CFQ scores reported by significant others showed clear group differences in everyday lapses of attention. Despite this, group differences in SART errors of commission were small and non-significant, and the correlations between SART errors and CFQ scores were small within both groups. Further analyses excluding participants with invalid score profiles, or restricting the analysis to the first performance of the SART failed to alter the results. These findings suggest that more research is needed to establish the validity of the SART as a measure of sustained attention after TBI, and to determine under what circumstances the original findings hold.

Adolescent↗

PubMed1990

Sustained subthreshold-for-twitch depolarization in rat single ventricular myocytes causes sustained calcium channel activation and sarcoplasmic reticulum calcium release.

Single rat ventricular myocytes, voltage-clamped at -50 to -40 mV, were depolarized in small steps in order to define the mechanisms that govern the increase in cytosolic [Ca2+] (Cai) and contraction, measured as a reduction in myocyte length. Small (3-5 mV), sustained (seconds) depolarizations that caused a small inward or no detectable change in current were followed after a delay by small (less than 2% of the resting length), steady reductions in cell length measured via a photodiode array, and small, steady increases in Cai measured by changes in Indo-1 fluorescence. Larger (greater than -30 and less than -20 mV), sustained depolarizations produced phasic Ca2+ currents, Cai transients, and twitch contractions, followed by a steady current and a steady increase in Cai and contraction. Nitrendipine (or Cd, verapamil, or Ni) abolished the steady contraction and always produced an outward shift in steady current. The steady, nitrendipine-sensitive current and sustained increase in Cai and contraction exhibited a similar voltage dependence over the voltage range between -40 and -20 mV. 2 microM ryanodine in the presence of intact Ca2+ channel activity also abolished the steady increase in Cai and contraction over this voltage range. We conclude that when a sustained depolarization does not exceed about -20 mV, the resultant steady, graded contraction is due to SR Ca2+ release graded by a steady ("window") Ca2+ current. The existence of appreciable, sustained, graded Ca2+ release in response to Ca2+ current generated by arbitrarily small depolarizations is not compatible with any model of Ca2(+)-induced Ca2+ release in which the releasing effect of the Ca2+ channel current is mediated solely by Ca2+ entry into a common cytosolic pool. Our results therefore imply a distinction between the triggering and released Ca2+ pools.

Animals↗

PubMed2001

Indicators of sustainable production: a new tool for promoting business sustainability.

This paper proposes a new tool for promoting business sustainability--indicators of sustainable production. It discusses the business case for sustainable development and introduces the concept of sustainable production as a way to equally address different aspects of production (environmental and occupational, social and economic). Indicators are suggested as a tool for operationalizing this concept and their objectives, scope, and desirable qualities are outlined. The paper concludes with some recommendations for developing indicators of sustainable production.

Journal Article↗

PubMed1988

Sustained ventricular arrhythmias: differences between survivors of cardiac arrest and patients with recurrent sustained ventricular tachycardia.

Clinical, angiographic, echocardiographic and electrophysiologic data were examined in 101 patients with a history of sustained ventricular arrhythmia not associated with acute myocardial infarction. These patients included 66 survivors of out of hospital cardiac arrest and 35 patients presenting with hemodynamically well tolerated sustained ventricular tachycardia. On univariate analysis, patients in the cardiac arrest group had a lower incidence of previous myocardial infarction and left ventricular aneurysm and a higher ejection fraction compared with the ventricular tachycardia group. During electrophysiologic testing, the arrhythmia induced in the patients in the cardiac arrest group was fast and polymorphic and frequently degenerated into ventricular fibrillation. In contrast, in the ventricular tachycardia group, a slower, monomorphic and hemodynamically well tolerated ventricular tachycardia was commonly induced. On multivariate analysis, a polymorphic pattern of the induced ventricular arrhythmia was the only independent variable that distinguished the survivors of cardiac arrest from those presenting with sustained ventricular tachycardia. These results suggest that 1) the survivors of cardiac arrest and patients presenting with sustained well tolerated ventricular tachycardia are clinically distinct groups; and 2) the polymorphic tachycardia induced during programmed electrical stimulation in the survivors of cardiac arrest may indicate an unstable tachycardia mechanism. This may explain why these patients present with ventricular fibrillation and cardiac arrest, whereas others present with hemodynamically stable ventricular tachycardia.

Aged↗

PubMed2005

Bottom up and top down: analysis of participatory processes for sustainability indicator identification as a pathway to community empowerment and sustainable environmental management.

The modern environmental management literature stresses the need for community involvement to identify indicators to monitor progress towards sustainable development and environmental management goals. The purpose of this paper is to assess the impact of participatory processes on sustainability indicator identification and environmental management in three disparate case studies. The first is a process of developing partnerships between First Nations communities, environmental groups, and forestry companies to resolve conflicts over forest management in Western Canada. The second describes a situation in Botswana where local pastoral communities worked with development researchers to reduce desertification. The third case study details an on-going government led process of developing sustainability indicators in Guernsey, UK, that was designed to monitor the environmental, social, and economic impacts of changes in the economy. The comparative assessment between case studies allows us to draw three primary conclusions. (1) The identification and collection of sustainability indicators not only provide valuable databases for making management decisions, but the process of engaging people to select indicators also provides an opportunity for community empowerment that conventional development approaches have failed to provide. (2) Multi-stakeholder processes must formally feed into decision-making forums or they risk being viewed as irrelevant by policy-makers and stakeholders. (3) Since ecological boundaries rarely meet up with political jurisdictions, it is necessary to be flexible when choosing the scale at which monitoring and decision-making occurs. This requires an awareness of major environmental pathways that run through landscapes to understand how seemingly remote areas may be connected in ways that are not immediately apparent.

Botswana↗

PubMed1985

Sustained attention and sustained effort after closed head injury: detection and 0.10 Hz heart rate variability in a low event rate vigilance task.

In closed head injury patients impaired sustained attention has been used to explain poor performance of complex tasks. However, this basic capacity was never adequately investigated. We investigated sustained attention in an auditory vigilance task and found no evidence at all for an impairment. With an interval of about three months 8 patients, tested in the first half year after closed head injury, and 8 healthy control subjects were confronted twice with a low event rate vigilance task. This yielded measures of signal detection and response latency. Also the amplitude of 0.10 Hz Heart Rate Variability, a power spectral measure, was calculated to indicate sustained effort. Hypotheses that patients would manifest stronger effects of time-on-task on performance and effort were not supported. Independent of sustained attention patients differed from controls in terms of response latencies and sensitivity of discriminating small differences of loudness especially on the first occasion.

Adolescent↗

PubMed1993

Australian registered nurse medical device education: a comparison of life-sustaining and non-life-sustaining devices.

Registered nurses are primarily responsible for the use of medical devices in direct patient care. This cross-sectional survey compared how and what 139 registered nurses working in a variety of wards/units in a 1000-bed tertiary care hospital in South Australia initially learned about the life-sustaining and non-life-sustaining medical devices they use. Furthermore, the consequences of device use both for patients and staff were explored. How and what registered nurses initially learned about life-sustaining and non-life-sustaining devices were remarkably similar. Consequences of device use, which included increased or decreased quality of care, increased nurse stress and patient harm, were related, in part, to knowledgeable and proficient device use. Thus, device education for nurses is essential and warrants further exploration.

Adult↗

PubMed2002

alpha-Thrombin induces rapid and sustained Akt phosphorylation by beta-arrestin1-dependent and -independent mechanisms, and only the sustained Akt phosphorylation is essential for G1 phase progression.

In Chinese hamster embryonic fibroblasts (IIC9 cells) alpha-thrombin activates the MAPK(ERK) and phosphatidylinositol 3-OH-kinase (PI 3-kinase)/Akt pathways, and both are essential for progression through the G(1) phase of the cell cycle. We investigated in IIC9 cells, the role of beta-arrestin1 in alpha-thrombin signaling to these pathways. alpha-Thrombin stimulates rapid and sustained PI 3-kinase and Akt activities. Expression of a dominant negative beta-arrestin1 (beta-arrestin1(V53D)) inhibits rapid but not sustained PI 3-kinase and Akt activities. Surprisingly, expression of beta-arrestin1(V53D) does not block activation of the MAPK(ERK) pathway. PI 3-kinase and Akt activities are also inhibited by expression of a beta-arrestin1 mutant, which impairs binding to c-Src (beta-arrestin1(P91G-P121E)), indicating the involvement of c-Src in the rapid stimulation of the PI 3-kinase/Akt pathway. Consistent with these results, PP1, a selective inhibitor of c-Src family kinases, prevents alpha-thrombin-stimulated Akt phosphorylation. Expression of beta- arrestin1(V53D) does not prevent G(1) progression, as its expression has no effect on [(3)H]thymidine incorporation into DNA. In agreement with the ineffectiveness of beta-arrestin1(V53D) to block G(1) progression, cyclin D1 protein amounts and CDK4-cyclin D1 activity is unaffected by expression of beta-arrestin1(V53D). Thus in IIC9 cells, alpha-thrombin activates rapid beta-arrestin1-dependent and sustained beta-arrestin1-independent Akt activity, suggesting that two mechanisms are involved. Furthermore, although blocking the beta-arrestin1-independent PI 3-kinase/Akt pathway prevents G(1) progression, inhibition of the beta-arrestin1-dependent pathway does not, indicating different roles for the rapid and sustained activities.

Animals↗

PubMed1999

Cyanide-resistant, ATP-synthesis-sustained, and uncoupling-protein-sustained respiration during postharvest ripening of tomato fruit

Tomato (Lycopersicon esculentum) mitochondria contain both alternative oxidase (AOX) and uncoupling protein as energy-dissipating systems that can decrease the efficiency of oxidative phosphorylation. We followed the cyanide (CN)-resistant, ATP-synthesis-sustained, and uncoupling-protein-sustained respiration of isolated mitochondria, as well as the immunologically detectable levels of uncoupling protein and AOX, during tomato fruit ripening from the mature green stage to the red stage. The AOX protein level and CN-resistant respiration of isolated mitochondria decreased with ripening from the green to the red stage. The ATP-synthesis-sustained respiration followed the same behavior. In contrast, the level of uncoupling protein and the total uncoupling-protein-sustained respiration of isolated mitochondria decreased from only the yellow stage on. We observed an acute inhibition of the CN-resistant respiration by linoleic acid in the micromolar range. These results suggest that the two energy-dissipating systems could have different roles during the ripening process.

Journal Article↗

PubMed2004

Manifesto for sustainable investment: investing for a sustainable future.

Environmental, labor, and non-governmental organizations in Europe are waging a campaign for sustainable investment to hold members of the European Union to their pledges to work for sustainable development and sustainable societies. The comment explains how to achieve sustainability by taking action at many levels of society.

Journal Article↗

PubMedDate not supplied

Following sustainable development in relation to the north-south dialogue: ecosystem health and sustainability indicators.

The necessity for policy makers to follow the processes in relation to sustainability demands new tools for management, a major aspect of which is integrated attention to economic and sociocultural influences together with environmental issues. North and South have specific positions and responsibilities with regard to sustainable development, and management tools--such as indicators--should reflect them. Because the North-South dialogue is changing, different approaches to deal with the relationships are needed (e.g., introduction of reciprocity, equity, and participation), while at the same time doing justice to the individual social, economic, and cultural characteristics of a country. Ecosystem health can be defined by requirements such as resilience, vigor, organization, and relations, which may be used for totally different systems as well. Because integration is a crucial aspect of the new tools, it is argued that integrating conceptual tools such as the environment-economy-society triangle, the PSIR-causality chain, and the Daly triangle in addition to other described integration tools is fundamental for decision makers. Crucial issues when dealing with indicators for sustainable development are integration and balance, attention to users, use of system characteristics, and understanding southern perspectives in this context.

Conservation of Natural Resources↗