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Biomedical subjects

D B Pyne

Publications and source records attributed to D B Pyne.

13 recordsLinked to original sources
PubMed1999

Salivary IgA levels and infection risk in elite swimmers.

UNLABELLED: The effects of exercise on the immune system has been shown to be dependent on the level of fitness of the subjects, the degree of intensity, and the duration of the exercise. A reduction in salivary IgA levels occurs after individual sessions of exercise. PURPOSE: The purpose of this study was to assess the relationship between changes in salivary IgA and training volume, psychological stress, and infection rates in a cohort of 26 elite swimmers over a 7-month training period and to compare the changes with a group of 12 moderately exercising controls. METHODS: Salivary IgA concentrations were measured by an electroimmunodiffusion. Exercise gradings were assessed by a standardized aerobic-anaerobic rating system. Psychological stress/anxiety was evaluated by the Spielberger State-Trait Anxiety Inventory. Infections were physician-verified. RESULTS: Salivary IgA levels showed an inverse correlation with the number of infections in both elite swimmers and moderately exercising control subjects. The pretraining salivary IgA levels in swimmers were 4.1% lower for each additional month of training and 5.8% lower for each additional infection. The posttraining salivary IgA levels in swimmers were not significantly correlated with infection rates but were 8.5% lower for each additional 1 km swum in a training session and 7.0% lower for each additional month of training. The number of infections observed in the elite swimmers was predicted from regression models by the preseason (P = 0.05) and the mean pretraining salivary IgA levels (P = 0.006). The trends in pretraining salivary IgA levels over the 7-month season, calculated as individual slopes of pretraining IgA levels over time, were also predictive of the number of infections (P = 0.03) in the swimmers. CONCLUSIONS: These results indicate that measurement of salivary IgA levels over a training season may be predictive for athletes at risk of infection.

Adolescent↗
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↗
PubMed1997

Exercise, training, and neutrophil function.

Although neutrophils are critical to host defense, they are also involved in the pathology of various inflammatory diseases. Neutrophils, representing 60% of circulating leukocytes in human subjects, are readily accessible to experimental investigation. Discrete aspects of, neutrophil function can be quickly and accurately assessed in vitro using a variety of techniques that involve assessment of intracellular and extracellular functional activities. Moderate exercise has variable effects on neutrophil function, but intense exercise is potentially immunosuppressive. Endurance training also suppresses most neutrophil functions chronically. A greater understanding of some fundamental aspects of neutrophil function and the uncovering of newly defined roles underlines potential applications in general and sports medicine. However, the practical value of this knowledge for monitoring the health and training programs of elite athletes requires further clarification. The current knowledge of neutrophil and immune functional measurements has not progressed to an extent that routine profiling in athletes can be used diagnostically.

Animals↗
PubMed1997

A treadmill protocol to investigate independently the metabolic and mechanical stress of exercise.

The purpose of this study was to describe an experimental treadmill model for the independent assessment of metabolic and mechanical stress associated with exercise. Eight well-trained male runners (VO2max 61.2 ml.kg-1.min-1) undertook, on different days, three 40 min bouts (consisting of 8 x 5 min work intervals) of treadmill running: uphill, downhill and near-level. Mean %VO2 max was 90.0, 52.7 and 52.2 for uphill, near-level and downhill running respectively. Oxygen uptake increased (p < 0.05) across the eight work intervals during uphill running, with non-significant increases in both near-level and downhill running. In contrast, heart rate increased (p < 0.05) with uphill and downhill, but not near-level running. Blood lactate concentration was higher (p < 0.01) and plasma pH lower (p < 0.01) after uphill running compared with downhill and near-level running. Plasma creatine kinase activity was elevated (p < 0.05) immediately after uphill running and 24 hours after downhill running (p < 0.05). Subjective rating of delayed onset muscle soreness was elevated (p < 0.05) at 24 and 48 hours after downhill running only. There were no significant changes in the plasma concentration of the inflammatory mediators interleukin-1beta, complement component C3a and C reactive protein. Given the observed differences in cardiorespiratory responses and indicators of muscle damage and soreness, this experimental model could be employed to investigate, independently, the metabolic and mechanical stress of exercise.

Adult↗
PubMed1996

Exercise and the neutrophil oxidative burst: biological and experimental variability.

The effect of acute bouts of moderate-intensity running and cycling on the neutrophil oxidative burst was examined. Eight well-trained male runners in group 1 each undertook, on different days, either two 40-min bouts of running (run 1 and run 2) separated by a 1-h recovery period, or 40 min of moderate cycling. Blood leucocyte (+49%) and granulocyte (+57%) counts increased (P < 0.05) with moderate running, but only the leucocyte count (+27%) was elevated significantly during moderate cycling. Chemiluminescence activity and superoxide anion release decreased after run 1 (-61%, P < 0.05) and after 30 min of cycling (-53%, P < 0.05), with no significant changes in the intracellular release of hydrogen peroxide. The same measures were also assessed at rest in a group of eight male volunteers (group 2) with no significant difference in neutrophil activity for samples treated in parallel or 1 h apart. These data suggest that while neutrophils are mobilised into the circulation in the first few hours following moderate exercise, their oxidative burst is temporarily inhibited. These effects were due to exercise per se and not to temporal variability or intra-assay variation.

Adult↗
PubMed1996

Pneumococcal antibody responses in elite swimmers.

The ability of elite swimmers to mount an antibody response to the pneumococcal vaccine, Pneumovax 23, was assessed at the end of an intensive 12-week training programme. Antibody titres to six pneumococcal polysaccharide types were measured in 20 elite swimmers (10 male, 10 female) aged 17-23 years and 19 sedentary age- and sex-matched students (eight male, 11 female) aged 18-23 years. Blood samples were tested 14 days apart to assess the magnitude of the antibody response and changes in serum immunoglobulin isotypes and IgG subclasses. There were no significant differences in any of the pneumococcal antibody responses to the Pneumovax between swimmers and controls, and no gender effect, either before or after vaccination. The clinically adequate response to the vaccine was greatest for the pneumococcal serotype 4, which was 97% for the total study population. There were no significant correlations between the magnitude of any of the pneumococcal antibody responses and (i) changes in the scores for the swimmers' international performance; (ii) infection rates in either swimmers or controls; (iii) any psychological variables, assessed by the Profile of Mood States (POMS) questionnaire for either swimmers or controls. Swimmers had significantly lower concentrations of serum IgG2 (P = 0.04) and IgG3 (P = 0.002) before pneumococcal vaccination. The swimmers had an increase in all immunoglobulin isotypes and IgG subclasses post-vaccination, suggesting a polyclonal response to the vaccine that was not observed in control subjects. The magnitude of the subclass responses after vaccination was significantly greater in swimmers compared with controls for IgG1 (P = 0.04), IgG3 (P = 0.04) and IgG4 (P = 0.01). The data indicated that elite swimmers undertaking an intensive training programme were capable of mounting an antibody response to pneumococcal antigens equivalent to that of age- and sex-matched sedentary control subjects, despite the swimmers having lower prevaccination levels of serum immunoglobulins.

Adolescent↗
PubMed1996

Effect of oral creatine supplementation on single-effort sprint performance in elite swimmers.

Oral supplementation with creatine monohydrate (Cr.H2O) has been reported to increase muscle creatine phosphate levels. The aim of the present study was to determine the effect of such supplementation on performance of a single-effort sprint by elite swimmers. Thirty-two elite swimmers (M = 18, F = 14; age = 17-25 years) from the Australian Institute of Sport were tested on two occasions, 1 week apart. Tests performed were 25-m, 50-m, and 100-m maximal effort sprints (electronically timed with dive start, swimmers performing their best stroke), each with approximately 10 min active recovery. A 10-s maximal leg ergometry test was also undertaken. Swimmers were divided into two groups matched for sex, stroke/event, and sprint time over 50 m, and groups were randomly assigned to 5 days of Cr.H2O supplementation (4 . day-1 x 5 g Cr.H2O + 2 g sucrose, n = 16) or placebo (4 . day-1 x 5 g Polycose + 2 g sucrose, n = 16) prior to the second trial. Results revealed no significant differences between the group means for sprint times or between 10-s maximal leg ergometry power and work. This study does not support the hypothesis that creatine supplementation enhances single-effort sprint ability of elite swimmers.

Adolescent↗
PubMed1996

Moderate exercise triggers both priming and activation of neutrophil subpopulations.

We investigated how moderate exercise affects neutrophil microbicidal activity and whether exercise-induced responses are associated with changes in growth hormone (GH) secretion. Biological fluctuations were controlled for and GH secretion was manipulated by glucose ingestion. In eight men, 1 h of moderate exercise increased intracellular H2O2 generation in response to phorbol 12-myristate 13-acetate stimulation by threefold (P = 0.025) and complement receptor expression by 20% (P = 0.045). These responses were accompanied by a twofold increase in the plasma concentration of elastase, a marker of neutrophil activation in vivo. The plasma concentration of GH increased 10-fold after exercise, but this was reduced to 3-fold by glucose ingestion (P < 0.001), which also blunted elastase release (P < 0.001). Although the magnitude of H2O2 generation increased in proportion to the increase in plasma GH concentration, it declined progressively once this exceeded 20 ng/ml. The net response of neutrophils to exercise may represent a balance between the individual responses of subpopulations that are unaffected, primed, or fully activated by circulating mediators that respond to exercise and to dietary glucose intake.

Adult↗
PubMed1995

The effect on immunity of long-term intensive training in elite swimmers.

The impact of long-term training on systemic and mucosal immunity was assessed prospectively in a cohort of elite swimmers over a 7-month training season in preparation for national championships. The results indicated significant suppression (P < 0.05) of serum IgA, IgG and IgM and salivary IgA concentration in athletes associated with long-term training at an intensive level. There was also a trend towards lower IgG2 subclass levels in serum in athletes compared with controls (P = 0.07). There were no significant changes in numbers or percentages of B or T cell subsets, but there was a significant fall in natural killer (NK) cell numbers and percentages in athletes over the training season (P < 0.05). After individual training sessions there was a significant decrease in salivary IgA levels for athletes compared with controls (P = 0.002). In athletes there was a downward trend in salivary IgA levels over the 7-month training period in both the pre-exercise (P = 0.06) and post-exercise samples (P = 0.04). There were no significant trends in salivary IgG levels over the study period in either athletes or controls. The only significant change in salivary IgM levels was an increase in detection rate in the pre-competition phase in athletes (P = 0.03). The study suggests that training of elite athletes at an intensive level over both short- and long-time frames suppresses both systemic and mucosal immunity. Protracted immune suppression linked with prolonged training may determine susceptibility to infection, particularly at times of major competitions.

Adolescent↗
PubMed1995

Effects of an intensive 12-wk training program by elite swimmers on neutrophil oxidative activity.

The effects of an intensive 12-wk training program by 12 national-level swimmers on neutrophil oxidative activity were studied. Eleven sedentary (untrained) subjects (6 males and 5 females) served as environmental controls. Blood samples (10 ml) were taken at rest from an antecubital vein and neutrophils isolated by standard separation techniques. The oxidative burst activity of isolated neutrophils was assessed with an in vitro flow cytometric assay that used the fluorescent probe dihydrorhodamine 123. Two-way ANOVA (repeated measures) showed that oxidative activity was lower (P < 0.05) in the elite swimmers compared with the sedentary control group across the 12-wk period. Analysis of cells from swimmers in training was made: repeated measures ANOVA provided evidence of a significant decline (P < 0.05) in the number of cells responding positively ito in vitro challenge. Despite this decline, there was no significant difference in self-reported upper respiratory tract infection rate between the swimmers and sedentary individuals. These data show that: (i) elite swimmers undertaking intensive training have a significantly lower neutrophil oxidative activity at rest than do age- and sex-matched sedentary individuals; (ii) aspects of oxidative activity in swimmers are further suppressed during periods of strenuous training, and (iii) the extent of the suppression does not appear to be of clinical significance.

Adult↗
PubMed1994

Regulation of neutrophil function during exercise.

In recent years there has been considerable interest in how exercise and training may affect the immune system. There is now substantial cross-sectional and epidemiological evidence that exercise causes significant changes in the distribution and function of a number of cellular and humoral immune parameters. Neutrophils represent one of the key nonspecific host defence cell populations responsible for the phagocytosis of many microbial, bacterial and viral pathogens. The neutrophil is also known to be involved in the synthesis and release of immunomodulatory cytokines that influence both T cell and B cell activities. Therefore, it plays an important role in both the efferent (phagocytosis and degranulation) and afferent (release of immunomodulatory molecules) limbs of the immune response. Neutrophils and macrophages respond both to phagocytosable particles (e.g. bacteria, viruses and cell debris) and to a number of soluble factors. There is an increase in the number of circulating neutrophils with exercise as a result of demargination of cells from endothelial tissues (mediated by catecholamines) and bone marrow (mediated by cortisol), or as part of the phagocytic and inflammatory response to exercise-induced tissue damage. Following exercise-induced mobilisation into the circulation and migration into tissues, neutrophils undergo adherence, phagocytosis (engulfment) of bacteria or tissue fragments, degranulation of cytoplasmic granules and, ultimately, activation of the respiratory burst. The capacity of the respiratory burst largely determines the cytotoxic potential of the neutrophil. The respiratory burst involves a sudden increase in nonmitochondrial oxidative metabolism, resulting in the production of the superoxide anion (O2-) and other reactive oxygen species by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase enzyme complex located at the plasma membrane. Although the biochemistry of the respiratory burst has been well studied, the mechanisms by which exercise and training may influence its activity are not well characterised or understood. Studies on the acute effects of exercise show that exercise generally elicits an initial activation of neutrophils-evidenced by release of cytoplasmic enzymes (degranulation) with secondary changes in key effector functions such as the phagocytic and respiratory burst activity. The nature of the functional changes is still unclear, as some studies show a transient suppression of the respiratory burst and/or phagocytic capacity immediately after exercise, while others report that moderate intensity exercise elicits an enhanced response. The variability in findings may be attributable to differences in the age, gender and initial fitness levels of the people studied, the intensity and duration of the exercise protocols used, and the different methodological procedures employed.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Degranulation↗
PubMedDate not supplied

Exercise-induced muscle damage and inflammation: a review.

Unaccustomed exercise may result in significant damage to skeletal muscle and cause delayed onset muscle soreness (DOMS) in both recreational and elite athletes. Two basic mechanisms-'metabolic' and 'mechanical' stress--have been proposed to explain how exercise initiates damage to skeletal muscle fibres. The extent of damage, particularly after eccentrically-biased exercise, has been assessed by histological and ultrastructural examination, and the measurement of the efflux of cytosolic enzymes into the circulation. The role of reactive oxygen species in the mediation of exercise-induced oxidative damage to muscle and the protection offered by anti-oxidant defence systems have been well studied. Free radical generation is normally estimated by indirect methods such as chemiluminescence, spectrophotometry, flow cytometry, or the measurement of products of lipid peroxidation such as malondialdehyde (MDA) and thiobarbituric acid reactive substances (TBARS). Although several theories have been proposed to account for the DOMS phenomenon, the underlying mechanisms are still to be elucidated. A group of proteins known collectively as cytokines regulate inflammatory and immunological processes involved in the repair of damaged tissue.

Cytokines↗