Showing papers by "Michael Gleeson published in 2012"

Respiratory infection risk in athletes: association with antigen‐stimulated IL‐10 production and salivary IgA secretion

Abstract: The purpose of this study was to examine factors influencing susceptibility to upper respiratory tract infections (URTI) in 18–35-year-old men and women engaged in endurance-based physical activity during the winter months Eighty individuals (46 males, 34 females) provided resting blood and saliva samples for determination of markers of systemic immunity Weekly training and illness logs were kept for the following 4 months Thirty subjects did not experience an URTI episode and 24 subjects experienced 3 or more weeks of URTI symptoms These illness-prone subjects had higher training loads and had ∼25-fold higher interleukin (IL)-4 and IL-10 production by antigen-stimulated whole blood culture than the illness-free subjects Illness-prone subjects also had significantly lower saliva S-IgA secretion rate and higher plasma IgM (but not IgA or IgG) concentration than the illness-free subjects There were no differences in circulating numbers of leukocyte subtypes or lymphocyte subsets between the illness-prone and illness-free subjects The production of IL-10 was positively correlated and the S-IgA secretion rate was negatively correlated with the number of weeks with infection symptoms It is concluded that high IL-10 production in response to antigen challenge and low S-IgA secretion are risk factors for development of URTI in physically active individuals

Effects of a Lactobacillus salivarius probiotic intervention on infection, cold symptom duration and severity, and mucosal immunity in endurance athletes

Abstract: The purpose of this study was to examine the effects of a probiotic supplement during 4 mo of spring training in men and women engaged in endurance-based physical activities on incidence of upper respiratory tract infections (URTI) and mucosal immune markers. Sixty-six highly active individuals were randomized to probiotic (n = 33) or placebo (n = 33) groups and, under double-blind procedures, received probiotic (PRO: Lactobacillus salivarius, 2 × 1010 bacterium colony-forming units) or placebo (PLA) daily for 16 wk. Resting blood and saliva samples were collected at baseline and after 8 and 16 wk. Weekly training and illness logs were kept. Fifty-four subjects completed the study (n = 27 PRO, n = 27 PLA). The proportion of subjects on PRO who experienced 1 or more wk with URTI symptoms was not different from that of those on PLA (PRO .58, PLA .59; p = .947). The number of URTI episodes was similar in the 2 groups (PRO 1.6 ± 0.3, PLA 1.4 ± 0.3; p = .710). Severity and duration of symptoms were not significantly different between treatments. Blood leukocyte, neutrophil, monocyte, and lymphocyte counts; saliva IgA; and lysozyme concentrations did not change over the course of the study and were not different on PRO compared with PLA. Regular ingestion of L. salivarius does not appear to be beneficial in reducing the frequency of URTI in an athletic cohort and does not affect blood leukocyte counts or levels of salivary antimicrobial proteins during a spring period of training and competition.

The effect of acute pre-exercise dark chocolate consumption on plasma antioxidant status, oxidative stress and immunoendocrine responses to prolonged exercise.

Abstract: Acute antioxidant supplementation may modulate oxidative stress and some immune perturbations that typically occur following prolonged exercise. The aims of the present study were to examine the effects of acutely consuming dark chocolate (high polyphenol content) on plasma antioxidant capacity, markers of oxidative stress and immunoendocrine responses to prolonged exercise. Fourteen healthy men cycled for 2.5 h at ~60% maximal oxygen uptake 2 h after consuming 100 g dark chocolate (DC), an isomacronutrient control bar (CC) or neither (BL) in a randomised-counterbalanced design. DC enhanced pre-exercise antioxidant status (P = 0.003) and reduced by trend (P = 0.088) 1 h post-exercise plasma free [F2-isoprostane] compared with CC (also, [F2-isoprostane] increased post-exercise in CC and BL but not DC trials). Plasma insulin concentration was significantly higher pre-exercise (P = 0.012) and 1 h post-exercise (P = 0.026) in the DC compared with the CC trial. There was a better maintenance of plasma glucose concentration on the DC trial (2-way ANOVA trial × time interaction P = 0.001), which decreased post-exercise in all trials but was significantly higher 1 h post-exercise (P = 0.039) in the DC trial. There were no between trial differences in the temporal responses (trial × time interactions all P > 0.05) of hypothalamic–pituitary–adrenal axis stress hormones, plasma interleukin-6, the magnitude of leukocytosis and neutrophilia and changes in neutrophil function. Acute DC consumption may affect insulin, glucose, antioxidant status and oxidative stress responses, but has minimal effects on immunoendocrine responses, to prolonged exercise.

The BASES expert statement on exercise, immunity, and infection

Abstract: An individual's level of physical activity influences their risk of infection, most likely by affecting immune function. Regular moderate exercise reduces the risk of infection compared with a sedentary lifestyle, but very prolonged bouts of exercise and periods of intensified training are associated with an increased risk of infection. There are several lifestyle, nutritional, and training strategies that can be adopted to limit the extent of exercise-induced immunodepression and minimize the risk of infection. This expert statement provides a background summarizing the evidence together with extensive conclusions and practical guidelines.

Cytokine production by monocytes, neutrophils, and dendritic cells is hampered by long-term intensive training in elite swimmers

Abstract: Elite level athletes seem to be prone to illness especially during heavy training phases. The aim of this study was to investigate the influence of long term intensive training on the functional features of innate immune cells from high competitive level swimmers, particularly the production of inflammatory mediators and the possible relationship with upper respiratory symptoms (URS) occurrence. A group of 18 swimmers and 11 healthy non athletes was studied. Peripheral blood samples were collected from athletes after 36 h of resting recovery from exercise at four times during the training season and at three times from non athletes. Samples were incubated in the presence or absence of LPS and IFN-γ and the frequency of cytokine-producing cells and the amount produced per cell were evaluated by flow cytometry. In addition, plasma cortisol levels were measured and URS recorded through daily logs. The athletes, but not the controls, showed a decrease in the number of monocytes, neutrophils, and dendritic cell (DC) subsets and in the amount of IL-1β, IL-6, IL-12, TNF-α, and MIP-1β produced after stimulation, over the training season. Differences were most noticeable between the first and second blood collections (initial increase in training volume). Athlete’s cortisol plasma levels partially correlated with training intensity and could help explain the reduced in vitro cell response to stimulation. Our results support the idea that long-term intensive training may affect the function of innate immune cells, reducing their capacity to respond to acute challenges, possibly contributing to an elevated risk of infection.

Method for producing a reflective optical element for euv-lithography

Abstract: Method for producing a reflective optical element for EUV lithography In order to reduce the tendency toward blistering and cracking as well as chipping in the topmost layers of a multilayer system in the presence of reactive hydrogen, a method for producing a reflective optical element (50) for EUV lithography, which element has a maximum reflectivity at an operating wavelength in the range of 5 nm to 20 nm, is proposed comprising the following steps: - applying to a substrate (52) a multilayer system (51) composed of thirty to sixty stacks (53) arranged one above another, wherein each stack has a layer (54) having a thickness dMLs composed of a material having a higher real part of the refractive index at the operating wavelength, and a layer (55) having a thickness dMLa composed of a material having a lower real part of the refractive index at the operating wavelength, wherein the thickness ratio is dMLa/(dMLa+dMLs) = ΓML, - applying one, two, three, four or five further stacks (56) to the multilayer system, said at least one further stack having a layer (54) having a thickness ds composed of a material having a higher real part of the refractive index at the operating wavelength, and a layer (55) having a thickness da composed of a material having a lower real part of the refractive index at the operating wavelength, wherein the thickness ratio is da/(da+ds) = Γ and wherein Γ ≠ ΓML.

A to Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance—Part 31

Abstract: This issue deals with the increasingly interesting topic of probiotics and also, slightly out of alphabetical order, with pycnogenol, a product usually associated with pine bark. Probiotics are food supplements containing live microorganisms. They modify intestinal microbiota in a way that enables beneficial bacteria to increase. An additional benefit is that probiotics in sufficient quantities also tend to decrease those species of bacteria which are considered harmful. It is suggested that this situation produces many potential benefits for the health and functioning of the digestive system, and also has a beneficial effect on immune function. In the short review below, the effects of probiotics and their efficacy in reducing infection incidence (or symptom severity/duration) in athletes are summarised. Pycnogenol supplementation has previously been considered to have a range of beneficial effects, including antioxidant and anti-inflammatory properties. ### M Gleeson Probiotics are food supplements that contain live microorganisms which when administered in adequate amounts can confer a health benefit on the host.1 There is now a reasonable body of evidence that regular consumption of probiotic strains that are proven to survive gut transit can modify the population of the gut-dwelling bacteria (microbiota) and influence immune function2,–,5 though it should be noted that such effects are dose- and strain-dependent. Probiotics modify the intestinal microbiota such that the numbers of beneficial bacteria increase and usually numbers of species considered harmful are decreased. Such changes have been associated with a range of potential benefits to the health and functioning …