Biomedical subjects

A Clarke

Publications and source records attributed to A Clarke.

At least 307 records · Page 17Linked to original sources

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The influence of feeding on oxygen consumption and nitrogen excretion in the Antarctic nemertean Parborlasia corrugatus.

The large nemertean Parborlasia corrugatus is common in nearshore benthic marine habitats around Antarctica, where it is an important predator and scavenger. Oxygen consumption and nitrogen excretion rates in worms freshly sampled from the field were low but similar to those reported for other polar marine ectotherms. Nitrogen was excreted primarily as ammonia (87%), with smaller amounts of urea (4%) and amines (9%). The O:N atomic ratio was low (10.4), indicating that free or protein-derived amino acids were important metabolic substrates. When worms were fed at ration levels ranging from 20% to 110% of body mass, both oxygen demand and ammonia excretion increased after feeding in a classic specific dynamic action response. Peak postprandial oxygen consumption was low (range, 1.5-2.6 times the prefeeding rate), and the duration of the specific dynamic action was unusually long (> 30 d). Both the energy used and the nitrogen excreted in the specific dynamic action scaled with meal size, although the fractions of ingested carbon and nitrogen used or lost were both very low, probably because of the large ration levels. We conclude that Parborlasia corrugatus has only a limited ability to increase its metabolic rate following a meal and, as a result, takes many days to process that meal fully.

Animals↗

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Effect of body size and ration on specific dynamic action in the Antarctic plunderfish, Harpagifer antarcticus Nybelin 1947.

The feeding energetics of the Antarctic spiny plunderfish (Harpagifer antarcticus) were examined with respect to the effect of both ration size and animal size. Fish of different sizes were fed single meals at one of two ration levels (2.5% wet body mass and satiation) to determine the maximum aerobic scope that could be elicited by the specific dynamic action. The excretion rates of ammonia, urea, and fluorescamine-positive substances were also monitored. Neither fish size nor ration had any effect on the factorial aerobic scope of feeding, which suggests that cellular metabolic processes associated with feeding were satiated by relatively small meals. The factorial scope in ammonia excretion was affected by both ration and fish size, indicating that respiration and excretion respond to a meal independently. The duration of the specific dynamic action response (240-390 h) increased with fish size but not ration, whereas both the time to reach the peak oxygen consumption and the duration of the ammonia response increased with ration but not fish size. The percentage of the ingested energy that was expended following feeding (the specific dynamic action coefficient) was high at low rations (approximately 56%) but lower (roughly 10%) at satiation rations. This is because the absolute energetic cost of processing a meal was largely independent of meal size. The change in O:N ratios after feeding was very ration-dependent; at low rations, O:N ratios increased, whereas at satiation rations, the O:N ratios decreased.

Animals↗

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How to do safe sternal reentry and the risk factors of redo cardiac surgery: a 21-year review with zero major cardiac injury.

OBJECTIVES: Resternotomy is a common part of cardiac surgical practice. Associated with resternotomy are the risks of cardiac injury and catastrophic hemorrhage and the subsequent elevated morbidity and mortality in the operating room or during the postoperative period. The technique of direct vision resternotomy is safe and has fewer, if any, serious cardiac injuries. The technique, the reduced need for groin cannulation and the overall low operative mortality and morbidity are the focus of this restrospective analysis. METHODS: The records of 495 patients undergoing 546 resternotomies over a 21-year period to January 2000 were reviewed. All consecutive reoperations by the one surgeon comprised patients over the age of 20 at first resternotomy: M:F 343:203, mean age 57 years (range 20 to 85, median age 60). The mean NYHA grade was 2.3 [with 67 patients (I), 273 (II), 159 (III), 43 (IV), and 4 (V classification)] with elective reoperation in 94.6%. Cardiac injury was graded into five groups and the incidence and reasons for groin cannulation estimated. The morbidity and mortality as a result of the reoperation and resternotomy were assessed. RESULTS: The hospital/30 day mortality was 2.9% (95% CI: 1.6%-4.4%) (16 deaths) over the 21 years. First (481), second (53), and third (12) resternotomies produced 307 uncomplicated technical reopenings, 203 slower but uncomplicated procedures, 9 minor superficial cardiac lacerations, and no moderate or severe cardiac injuries. Direct vision resternotomy is crystalized into the principle that only adhesions that are visualized from below are divided and only sternal bone that is freed of adhesions is sewn. Groin exposure was never performed prophylactically for resternotomy. Fourteen patients (2.6%) had such cannulation for aortic dissection/aneurysm (9 patients), excessive sternal adherence of cardiac structures (3 patients), presurgery cardiac arrest (1 patient), and high aortic cannulation desired and not possible (1 patient). The average postop blood loss was 594 mL (95% CI:558-631) in the first 12 hours. The need to return to the operating room for control of excessive bleeding was 2% (11 patients). Blood transfusion was given in 65% of the resternotomy procedures over the 21 years (mean 854 mL: 95% CI 765-945 mL) and 41% over the last 5 years. CONCLUSIONS: The technique of direct vision resternotomy has been associated with zero moderate or major cardiac injury/catastrophic hemorrhage at reoperation. Few patients have required groin cannulation. In the postoperative period, there was acceptable blood loss, transfusion rates, reduced morbidity, and moderate low mortality for this potentially high risk group.

Adult↗

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Experiences with redo aortic valve surgery.

OBJECTIVES AND METHODS: Reoperations are an integral part of a cardiac surgeon's practice. We share our experience of 546 reoperations over the last 21 years to January 2000, with the focus directed towards the timing of reoperation, reducing the mortality and morbidity of reoperation and rereplacement aortic valve surgery, and understanding the important risk factors. In addition, the precise technical steps that facilitate careful successful explantation of various devices (allograft, stented and stentless xenografts, and mechanical valves) are detailed. RESULTS: Optimal planned reoperation before deterioration to New York Heart Association Class III/IV levels and before unfavorable cardiac and comorbidity general system failure occurs has produced low mortality and morbidity as compared with first operation results. However, unfavorable delays and late rereferral result in mortality rates of up to 22% for emergency redo AVR for degenerated bioprostheses. CONCLUSION: Cardiac surgical units have the opportunity to establish a closer patient-surgeon relationship, which favors, when necessary, the optimal timing of reoperation. Knowledge of the more important risk factors and adherence to specific technical steps at explantation of various devices enhances satisfactory reoperation outcomes.

Aortic Valve↗

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The nursing management of intravenous drug therapy.

The implementation of intravenous (i.v.) drug therapy is an increasingly common experience for patients and one that carries a significant risk of damaging side-effects. Patients who require i.v. therapy are likely to be those most at risk should complications arise. It is therefore essential that healthcare professionals, involved in any aspect of i.v. therapy acquire and maintain the necessary knowledge and skills to ensure the delivery of safe and effective care (British Medical Association/Royal College of Nursing, 1993). This article explores the principles that underpin safe administration technique, identifies the risks and hazards associated with i.v. drug therapy and outlines the action necessary to manage these problems effectively.

Clinical Competence↗

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Using biography to enhance the nursing care of older people.

This article describes how the use of the biographical approach in nursing practice should enable a fuller understanding of older people as individuals, based on their lived experience. This, in turn, should affect the way in which nurses work with, and care for, older people, encouraging person-centred practice. First, drawing on a life story, the article describes the ways in which people's accounts of their past lives may provide an insight into their present needs, priorities and aspirations; it also helps to reveal and challenge our assumptions about later life. Second, the article discusses why the biographical approach is particularly appropriate for the care of older people in continuing care settings and how this approach could be undertaken.

Aged↗

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Raising a din.

Explore the source record for details and available documents.

Persons with Disabilities↗

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The care of older people.

This ongoing study examines the use of a biographical approach to enhance patient-centred care of older people.

Aged↗

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Changing attitudes through persuasive communication.

Nurses are uniquely placed to provide effective health education with the aim of promoting attitude and behavioural change. This article explores the literature relating to attitude formation, attitude change and the nature of persuasive communication, and identifies specific strategies that will be useful to all nurses.

Attitude to Health↗

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