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Title: The effects of military deployment and critical illness on energy homeostasis
Author: Hill, Neil Edward
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2012
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Maintaining energy balance is critical to military performance. Severely injured military personnel in intensive care inevitably develop a catabolic state which prolongs the recovery period. Understanding the effects of deployment and injury on energy homeostasis will aid tailoring of nutritional provision to military personnel. Body composition, physical fitness, dietary intake, gut hormone and leptin levels were measured in 249 Royal Marines before, during and after a six month operational deployment in Afghanistan. Wounded volunteers were followed up during recovery and rehabilitation. Royal Marines lost significant total, lean and fat mass in the first half of their tour, which did not affect physical fitness. Leptin was significantly correlated with fat mass changes. The cohort of wounded Royal Marines was too small and heterogeneous to draw meaningful conclusions from. The orexigenic gastric hormone ghrelin has been proposed to attenuate the loss of lean body mass seen after critical illness. To investigate the effect of ghrelin on recovery from critical illness a rodent model of prolonged critical illness with gradual recovery was developed. Male Wistar rats received intraperitoneal injections of the fungal wall derivative zymosan. Biochemical, metabolic and gut hormone profiles were characterised. Continuous subcutaneous infusion of ghrelin was started 48 hours after the insult and continued for 10 days. Muscle strength and histology, and body composition were determined. Zymosan caused significant weight loss and muscle mass and reduced food intake. Ghrelin-treated rats ate more food and gained more body mass than controls, but did not alter total body protein, muscle strength or muscle morphology, though it increased adiposity and promoted fat over carbohydrate metabolism. These studies suggest loss of moderate amounts of body mass in Royal Marines did not adversely affect measures of strength, and that the gastric hormone ghrelin is unlikely to accelerate recovery of lean body mass or muscle function in critical illness cachexia.
Supervisor: Murphy, Kevin Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available