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Biomedical subjects

M Gleeson

Publications and source records attributed to M Gleeson.

At least 55 records · Page 3Linked to original sources
PubMed1998

The effects of high-intensity intermittent exercise on the plasma concentrations of glutamine and organic acids.

Glutamine is an essential substrate for the proper functioning of cells of the immune system. Falls in plasma glutamine concentration after exercise may have deleterious consequences for immune cell function and render the individual more susceptible to infection. The purpose of the present study was to examine changes in plasma glutamine concentration (measured using a validated enzymatic spectrophotometric method) following an acute bout of intermittent high-intensity exercise. Eight well-trained male games players took part in the study. Subjects reported to the laboratory following an overnight fast and performed a 1-h cycle exercise task consisting of 20 1-min periods at 100% maximal O2 consumption (VO2max) each separated by 2 min of recovery at 30% VO2max. Venous blood samples were taken before exercise and at 5 min, 1 h, 2.5 h, 5 h and 24 h post-exercise. Glutamine was measured by enzymatic spectrophotometric determination of the ammonia concentration before and after treatment of the plasma with glutaminase (EC 3.5.1.2). Plasma glutamine concentration did not fall in the immediate post-exercise period [pre-exercise 681 (23) microM compared with 663 (46) microM at 5 min post-exercise, mean (SEM)], but fell to 572 (35) microM at 5 h post-exercise (P < 0.05 compared with pre-exercise). Plasma lactate concentration rose to 8.8 (1.0) mM at the end of exercise and fell to 1.8 (0.4) mM at 1 h post-exercise, but plasma concentrations of free fatty acids and beta-hydroxybutyrate both rose substantially in the post-exercise period (to 240% and 400% of pre-exercise levels, respectively). The circulating leucocyte count increased significantly during exercise (P < 0.01), continued to increase in the hours following exercise and peaked at 2.5 h post-exercise (mainly due to a neutrophilia). The fall in the plasma glutamine concentration at 5 h post-exercise could be due to increased renal uptake of glutamine, which generally occurs in conditions of metabolic acidosis or due to a greater removal of glutamine from the plasma resulting from the elevated circulating leucocyte count.

3-Hydroxybutyric Acid↗
PubMed1998

The effect of severe eccentric exercise-induced muscle damage on plasma elastase, glutamine and zinc concentrations.

The aim of this study was to determine if severe exercise-induced muscle damage alters the plasma concentrations of glutamine and zinc. Changes in plasma concentrations of glutamine, zinc and polymorphonuclear elastase (an index of phagocytic cell activation) were examined for up to 10 days following eccentric exercise of the knee extensors of one leg in eight untrained subjects. The exercise bout consisted of 20 repetitions of electrically stimulated eccentric muscle actions on an isokinetic dynamometer. Subjects experienced severe muscle soreness and large increases in plasma creatine kinase activity indicative of muscle fibre damage. Peak soreness occurred at 2 days post-exercise and peak creatine kinase activity [21714 (6416) U x l(-1) mean (SEM)] occurred at 3 days post-exercise (P < 0.01 compared with pre-exercise). Plasma elastase concentration was increased at 3 days post-exercise compared with pre-exercise (P < 0.05), and is presumably indicative of ongoing phagocytic leucocyte infiltration and activation in the damaged muscles. There were no significant changes in plasma zinc and glutamine concentrations in the days following eccentric exercise. We conclude that exercise-induced muscle damage does not produce changes in plasma glutamine or zinc concentrations despite evidence of phagocytic neutrophil activation.

Adult↗
PubMed1998

The effect of exercising to exhaustion at different intensities on saliva immunoglobulin A, protein and electrolyte secretion.

The quality and quantity of saliva may be important in defending against pathogens transmitted via the buccal cavity. The aim of the present study was to examine the effect of cycling to exhaustion at moderate and high intensity on various salivary parameters and the time course of recovery. Eighteen male subjects of mixed physical fitness took part in the study. Subjects performed two bouts of exercise on separate occasions at least one week apart. Following an overnight fast, subjects cycled on an electrically braked cycle ergometer at a work rate equivalent to 80% VO2max until exhaustion. On another occasion they cycled on the same ergometer at 55% VO2max for 3 h or to fatigue (whichever was sooner). The order of the rides was randomised. Timed, unstimulated saliva samples were collected pre-exercise, during exercise, at cessation of exercise and at 1, 2.5, 5 and 24 h post-exercise. Saliva samples were analysed for IgA, total protein and osmolality. Saliva flow rate was significantly reduced by exercise (P < 0.01). Saliva IgA concentration, secretion rate and ratio to osmolality increased during exercise (P < 0.01). IgA to protein ratio did not change significantly during exercise. Since saliva protein secretion rate increased during exercise (P < 0.01) it appears that correcting for loss of saliva water by expressing IgA relative to protein is misleading. IgA secretion rate and IgA to osmolality ratio are more appropriate measures and neither parameter was lowered by exercise. The results of this study indicate that exercise may detrimentally affect the quantity of saliva produced, but not the quality of saliva. Furthermore, when exercise is to exhaustion, the intensity of the bout does not appear to influence the saliva response. Neither exercise protocol had any long term effect on saliva as all variables recovered within 1 h post-exercise.

Adult↗
PubMed1998

Temperature regulation during exercise.

During strenuous exercise the body's heat production may exceed 1000 W. Some of the heat produced is stored, raising body core temperature by a few degrees. Rises in body temperature are sensed by central and skin thermoreceptors and this sensory information is processed by the hypothalamus to trigger appropriate effector responses. Other sensory inputs from baroreceptors and osmoreceptors can modify these responses. Evaporation of sweat and increased skin blood flow are effective mechanisms for the dissipation of heat from the body but dehydration impairs the capacity to sweat and lose body heat. Hot, humid environments or inappropriate clothing may compromise the ability to lose heat from the body. Exercise training improves tolerance to exercise in the heat by increasing the sensitivity of the sweat rate/core temperature relationship, decreasing the core temperature threshold for sweating and increasing total blood volume.

Blood Volume↗
PubMed1998

Effects of intensive exercise training on immunity in athletes.

A large number of studies have failed to show whether exercise-induced perturbations in immune function are associated with the incidence of infection. "Sports immunology", examining the interaction of physical, psychological and environmental stress on immunity, is emerging as a sub-discipline of sports medicine. A series of studies by our research team has profiled the immune responses of elite swimmers during training. Serum immunoglobulin and IgG subclass levels were lower in swimmers than controls. Suppression of mucosal immune parameters has been associated with the risk of upper respiratory tract infection. Swimmers with a lower pre-season salivary IgA and/or lower pre-exercise salivary IgA level were more likely to contract an URTI during a 7-month training period. In a shorter 12-week study, infected swimmers had a mean salivary IgM concentration that dropped more sharply after a single training session. Significant declines in natural killer cell count and neutrophil oxidative activity were not associated with URTI. Despite systemic and mucosal immunosuppression a cohort of swimmers were also able to mount an antibody response to pneumococcal vaccine equivalent to that of sedentary individuals. Observations of chronic suppression of aspects of host defence and the significant relationship between changes in mucosal immune parameters and URTI, provide a framework for assessment of the immune status of athletes. The underlying causes of upper respiratory tract distress symptoms may be infective, inflammatory or allergic in origin: a differential diagnosis has implications for treatment and management.

Exercise↗
PubMed1998

Effect of low- and high-carbohydrate diets on the plasma glutamine and circulating leukocyte responses to exercise.

We examined the effects of a low-carbohydrate (CHO) diet on the plasma glutamine and circulating leukocyte responses to prolonged strenuous exercise. Twelve untrained male subjects cycled for 60 min at 70% of maximal oxygen uptake on two separate occasions, 3 days apart. All subjects performed the first exercise task after a normal diet; they completed the second exercise task after 3 days on either a high-CHO diet (75 +/- 8% CHO, n = 6) or a low-CHO diet (7 +/- 4% CHO, n = 6). The low-CHO diet was associated with a larger rise in plasma cortisol during exercise, a greater fall in the plasma glutamine concentration during recovery, and a larger neutrophilia during the postexercise period. Exercise on the high-CHO diet did not affect levels of plasma glutamine and circulating leukocytes. We conclude that CHO availability can influence the plasma glutamine and circulating leukocyte responses during recovery from intense prolonged exercise.

3-Hydroxybutyric Acid↗
PubMed1998

Epidemiological association of airway inflammation with asthma symptoms and airway hyperresponsiveness in childhood.

The role of airway inflammation in childhood asthma is not well defined, despite modern treatment approaches recommending potent anti-inflammatory therapy for an increasing number of children. In this study, induced sputum analysis was used to investigate the relationships among sputum inflammatory cells (eosinophils and mast cells), asthma symptoms, and airway hyperresponsiveness to hypertonic saline in a cohort of 170 children aged 8-14 years. Children who reported asthma symptoms in the past 2 wk had a 2. 25-fold (95% to CI, 1.20-4.24) increased odds of having significant sputum eosinophilia. Hyperresponsiveness to hypertonic saline was strongly associated with higher levels of sputum eosinophils ([OR] 4. 36, 1.70-11.20), sputum mast cells (OR 7.46, 2.48-22.75), and nasal eosinophils (OR 4.73, 1.89-11.86). Interestingly, boys were more likely than girls to have features of airway inflammation (sputum mast cells, OR 3.33, 1.15-9.65; nasal eosinophils, OR 3.25, 1.72-5. 97), which is consistent with the known increase in asthma prevalence in boys in this age group. Airway inflammation with eosinophils and mast cells is likely to be important in the pathogenesis of asthma in childhood. Induced sputum analysis can be used to evaluate this problem and has the potential to be a useful tool for monitoring therapy.

Adolescent↗
PubMed1998

Glutamine, exercise and immune function. Links and possible mechanisms.

Glutamine is the most abundant free amino acid in human muscle and plasma and is utilised at high rates by rapidly dividing cells, including leucocytes, to provide energy and optimal conditions for nucleotide biosynthesis. As such, it is considered to be essential for proper immune function. During various catabolic states including surgical trauma, infection, starvation and prolonged exercise, glutamine homeostasis is placed under stress. Falls in the plasma glutamine level (normal range 500 to 750 mumol/L after an overnight fast) have been reported following endurance events and prolonged exercise. These levels remain unchanged or temporarily elevated after short term, high intensity exercise. Plasma glutamine has also been reported to fall in patients with untreated diabetes mellitus, in diet-induced metabolic acidosis and in the recovery period following high intensity intermittent exercise. Common factors among all these stress states are rises in the plasma concentrations of cortisol and glucagon and an increased tissue requirement for glutamine for gluconeogenesis. It is suggested that increased gluconeogenesis and associated increases in hepatic, gut and renal glutamine uptake account for the depletion of plasma glutamine in catabolic stress states, including prolonged exercise. The short term effects of exercise on the plasma glutamine level may be cumulative, since heavy training has been shown to result in low plasma glutamine levels (< 500 mumol/L) requiring long periods of recovery. Furthermore, athletes experiencing discomfort from the overtraining syndrome exhibit lower resting levels of plasma glutamine than active healthy controls. Therefore, physical activity directly affects the availability of glutamine to the leucocytes and thus may influence immune function. The utility of plasma glutamine level as a marker of overtraining has recently been highlighted, but a consensus has not yet been reached concerning the best method of determining the level. Since injury, infection, nutritional status and acute exercise can all influence plasma glutamine level, these factors must be controlled and/or taken into consideration if plasma glutamine is to prove a useful marker of impending overtraining.

Animals↗
PubMed1998

Medicare. We can't afford to lose it.

With the promise of a federal election in the wind and the commonwealth and states battling about the amount of money required for adequate health care, it is timely to examine our health system, the politics, the policies on which it is based and the values which underpin it.

Australia↗
PubMed1998

Nurses, nursing and the unlicensed worker providing nursing care.

The issue of the unlicensed worker performing nursing work is indeed contentious. However, this worker, known variously as the Assistant in Nursing (AIN), the Personal Care Attendant (PCA), the Direct Care Worker, the Community Worker and so on has been part of the health care scene for many years.

Australia↗
PubMed1997

A prospective, randomized, double-blind study comparing lignocaine gel and plain lubricating gel in relieving pain during flexible cystoscopy.

OBJECTIVE: To determine the optimum duration for the retention of 2% lignocaine gel intraurethrally as an anaesthetic for flexible cystoscopy in men. PATIENTS AND METHODS: A prospective, randomized, double-blind, placebo-controlled trial was conducted in two parts. Initially, the importance of duration was determined, i.e. whether pain relief was significantly improved when lignocaine gel was instilled for longer than is currently practised. As pain relief was improved by retaining the lignocaine gel for longer, the optimum time was determined in a second trial. Initially, 90 patients were divided into four groups receiving 20 mL of 2% lignocaine gel or plain lubricating gel for 5 or 25 min. Subsequently, 60 men were divided into two groups receiving 20 ml of 2% lignocaine gel for 15 or 25 min. The patients' discomfort was recorded using a 4-point descriptive pain scale and a 100 mm non-graphical visual analogue scale. RESULTS: In the first study, those patients receiving lignocaine gel for 25 min experienced significantly less pain than the other three groups. In the second, lignocaine gel in the urethra for 15 min provided the same level of pain relief as lignocaine for 25 min. CONCLUSION: Pain during flexible cystoscopy can be significantly reduced when 20 mL of 2% lignocaine gel is left in the urethra for 15 min; lignocaine gel would be more effective when left for longer than is currently practised.

Analgesia↗
PubMed1997

Diet composition and the performance of high-intensity exercise.

The crucial role of muscle glycogen as a fuel during prolonged exercise is well established, and the effects of acute changes in dietary carbohydrate intake on muscle glycogen content and on endurance capacity are equally well known. More recently, it has been recognized that diet can also affect the performance of high-intensity exercise of short (2-7 min) duration. If the muscle glycogen content is lowered by prolonged (1-1.5 h) exhausting cycle exercise, and is subsequently kept low for 3-4 days by consumption of a diet deficient in carbohydrate (< 5% of total energy intake), there is a dramatic (approximately 10-30%) reduction in exercise capacity during cycling sustainable for about 5 min. The same effect is observed if exercise is preceded by 3-4 days on a carbohydrate-restricted diet or by a 24 h total fast without prior depletion of the muscle glycogen. Consumption of a diet high in carbohydrate (70% of total energy intake from carbohydrate) for 3-4 days before exercise improves exercise capacity during high-intensity exercise, although this effect is less consistent. The blood lactate concentration is always lower at the point of fatigue after a diet low in carbohydrate and higher after a diet high in carbohydrate than after a normal diet. Even when the duration of the exercise task is kept constant, the blood lactate concentration is higher after exercise on a diet high in carbohydrate than on a diet low in carbohydrate. Consumption of a low-carbohydrate isoenergetic diet is achieved by an increased intake of protein and fat. A high-protein diet, particularly when combined with a low carbohydrate intake, results in metabolic acidosis, which ensues within 24 h and persists for at least 4 days. This appears to be the result of an increase in the circulating concentrations of strong organic acids, particularly free fatty acids and 3-hydroxybutyrate, together with an increase in the total plasma protein concentration. This acidosis, rather than any decrease in the muscle glycogen content, may be responsible for the reduced exercise capacity in high-intensity exercise; this may be due to a reduced rate of efflux of lactate and hydrogen ions from the working muscles. Alternatively, the accumulation of acetyl groups in the carbohydrate-deprived state may reduce substrate flux through the pyruvate dehydrogenase complex, thus reducing aerobic energy supply and accelerating the onset of fatigue.

Acidosis, Lactic↗
PubMed1997

Defining obesity in patients undergoing orthotopic heart transplantation: body mass index versus percent body fat.

We examined body mass index (BMI) as a proxy for percent body fat among 26 men and women successfully undergoing orthotopic heart transplantation. Percent body fat was determined by use of bioelectrical impedance techniques. We found that, although BMI was well correlated with percent body fat (r = 0.58, p < 0.01), use of a BMI of greater than 27 kg/m2 to define obesity potentially misclassified patients when compared with defining obesity as a percentage of body fat as both greater than 30% (BMI = 9 of 26 patients vs percent body fat = 6 of 26 patients) and greater than 40% (BMI = 9 of 26 versus percent body fat = 1 of 9). We conclude that percent body fat measurements are more methodologically appropriate means for J Heart Lung Transplant 1997;16:563-5.

Adult↗