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Jaime S. Rosa, Christina D. Schwindt, Stacy R. Oliver, Szu-Yun Leu, Rebecca L. Flores and Pietro R. Galassetti

Leukocytosis contributes to exercise-induced immune modulation, which is a mechanism of cardiovascular protection. However, this process is poorly defined in children. We therefore measured leukocytes in 45 healthy, 18 overweight, 16 type 1 diabetic, and 8 asthmatic children at pre, end-, and 30-min postexercise (30-min intermittent or 6-min continuous). In all groups, total leukocytes, neutrophils, lymphocytes, and monocytes increased at end-exercise, but returned to baseline by 30-min postexercise, including neutrophils, previously reported to remain elevated for at least some exercise formats. This highly preserved pattern indicates the importance of the adaptive response to physical stress across multiple health conditions.

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Glen Davison and Michael Gleeson

The aim of the present study was to investigate the effect of vitamin C with or without carbohydrate consumed acutely in beverages before and during prolonged cycling on immunoendocrine responses. In a single blind, randomized manner six healthy, moderately trained males exercised for 2.5 h at 60% VO2max and consumed either placebo (PLA), carbohydrate (CHO, 6% w/v), vitamin C (VC, 0.15% w/v) or CHO+VC beverages before and during the bouts; trials were separated by 1 wk. CHO and CHO+VC significantly blunted the post-exercise increase in plasma concentrations of cortisol, ACTH, total leukocyte, and neutrophil counts and limited the decrease in plasma glucose concentration and bacteria-stimulated neutrophil degranulation. VC increased plasma antioxidant capacity (PAC) during exercise (P < 0.05) but had no effect on any of the immunoendocrine responses (P > 0.05). CHO+VC increased PAC compared to CHO but had no greater effects, above those observed with CHO alone, on any of the immunoendocrine responses. In conclusion, acute supplementation with a high dose of VC has little or no effect on the hormonal, interleukin-6, or immune response to prolonged exercise and combined ingestion of VC with CHO provides no additional effects compared with CHO alone.

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Michael Gleeson, Andrew K. Blannin, Neil P. Walsh, Nicolette C. Bishop and Anya M. Clark

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 andcirculaling leukocyte responses during recovery from intense prolonged exercise.

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Paul D. Loprinzi and Jeremy P. Loenneke

Objective:

Leukocyte telomere length (LTL) shortening is characteristic of aging and is associated with morbidity and mortality, independent of age. Research demonstrates that lower extremity muscular strength is associated with mobility, morbidity and mortality; however, no study, to our knowledge, had examined the association between lower extremity muscular strength and LTL, which was the purpose of this brief study.

Methods:

Data from the 1999–2002 NHANES was used (N = 2410; 50–85 years). Peak isokinetic knee extensor strength (IKES) was objectively measured with LTL assessed from a blood sample.

Results:

After adjustments, for every 50 N increase in IKES, participants had a 9% reduced odds (P = .04) of being in the 1st (vs. 4th) LTL quartile.

Discussion:

Lower extremity muscular strength is associated with LTL, suggesting a possible mechanism through which lower extremity muscular strength may be associated with morbidity and mortality.

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Tzai-Li Li, Ching-Ling Wu, Michael Gleeson and Clyde Williams

The purpose of this study was to determine the effect of pre-exercise high carbohydrate meals with high glycemic index (HGI) or low glycemic index (LGI) on blood leukocyte redistribution during subsequent endurance exercise. Eight male subjects performed a 90-min run on a treadmill at 70% VO2max 3 h after ingesting an isocaloric HGI or LGI meal with GI values of 77 and 37, respectively. Blood counts of leukocytes, and neutrophils and the neutrophil/lymphocyte ratio were significantly lower in LGI than HGI at 90 min of exercise (P < 0.05). The plasma glucose concentrations were significantly higher in LGI than HGI between 15 min and 45 min of exercise. There were, however, no differences in plasma cortisol, growth hormone, and interleukin-6 concentrations between trials. Thus, the GI of a pre-exercise meal influences leukocyte trafficking and plasma glucose but has limited effects on circulating stress hormone and cytokine responses to exercise.

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Vinicius Coneglian Santos, Adriana Cristina Levada-Pires, Sâmia Rocha Alves, Tânia Cristina Pithon-Curi, Rui Curi and Maria Fernanda Cury-Boaventura

Purpose:

To investigate the effects of docosahexaenoic-(DHA)-rich fish oil (FO) supplementation on lymphocyte function before and after a marathon race.

Methods:

Twenty-one athletes participated in this study. Eight marathon runners were supplemented with 3 g of FO daily for 60 d (FO group), and 13 athletes were not supplemented (C group). The following measures of lymphocytes were taken before and after the marathon: cell proliferation, cytokine production (IL-2, IL-10, TNF-α, and IL-4), and signs of cell death.

Results:

In the C group, the marathon had no effect on lymphocyte proliferation, DNA fragmentation, or mitochondrial membrane polarization; however, the marathon increased phosphatidylserine externalization (by 2.5-fold), induced a loss of plasma membrane integrity (by 20%), and decreased IL-2, TNF-α, and IL-10 production (by 55%, 95%, and 50%, respectively). FO supplementation did not prevent lymphocyte death induced by the marathon, as indicated by cell viability, DNA fragmentation, and phosphatidylserine externalization. However, FO supplementation increased lymphocyte proliferation before and after the marathon, and before the race, FO supplementation decreased IL-2, TNF-α, and IL-10 production in concanavalin-A-stimulated lymphocytes (by 55%, 95%, and 58%, respectively) compared with cells from the C group. The production of cytokines was not altered before or after the race in the FO group.

Conclusions:

DHA-rich FO supplementation increased lymphocyte proliferation and prevented a decrease in cytokine production, but it did not prevent lymphocyte death induced by participation in the marathon. Overall, DHA rich-FO supplementation has beneficial effects in preventing some of the changes in lymphocyte function induced by marathon participation.

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Tzai-Li Li and Michael Gleeson

This study compared immunoendocrine responses to a single bout of prolonged cycling at different times of day and to a 2nd bout of cycling at the same intensity on the same day. In a counterbalanced design, 8 men participated in 3 experimental trials separated by at least 4 d. In the afternoon exercise-only trial, subjects cycled for 2 h at 60% VO2max starting at 14:00. In the other 2 trials, subjects performed either 2 bouts of cycling at 60% VO2max for 2 h (starting at 09:00 and 14:00) or a separate resting trial. The single bout of prolonged exercise performed in the afternoon induced a larger neutrophilia and monocy-tosis than the identical bout of morning exercise, possibly the result of reduced carbohydrate availability and the circadian rhythm in cortisol levels. The 2nd prolonged exercise bout caused greater immunoendocrine responses but lower plasma glucose levels and neutrophil function compared with the 1st bout.

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Thiago R.S. Tenório, P. Babu Balagopal, Lars B. Andersen, Raphael M. Ritti-Dias, James O. Hill, Mara C. Lofrano-Prado and Wagner L. Prado

subtype leukocyte counts were determined by fluorescent flow cytometry using an automated hematology analyzer (Sysmex XE 2100 ™ ; Sysmex America, Inc, Mundelein, IL). Glucose concentrations were measured using the ADVIA 1650 automated analyzer (Bayer HealthCare Ltd, Tarrytown, NY). Serum tumor necrosis

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Stewart J. Laing, Samuel J. Oliver, Sally Wilson, Robert Walters, James L.J Bilzon and Neil P. Walsh

The aim was to investigate the effects of 48 hr of fluid, energy, or combined fluid and energy restriction on circulating leukocyte and lymphocyte subset counts (CD3+, CD4+, and CD8+) and bacterially stimulated neutrophil degranulation at rest and after exercise. Thirteen healthy men (M ± SEM age 21 ± 1 yr) participated in 4 randomized 48-hr trials. During control (CON) participants received their estimated energy (2,903 ± 17 kcal/day) and fluid (3,912 ± 140 ml/day) requirements. During fluid restriction (FR) they received their energy requirements and 193 ± 19 ml/day water to drink. During energy restriction (ER) they received their fluid requirements and 290 ± 6 kcal/day. Fluid and energy restriction (F+ER) was a combination of FR and ER. After 48 hr, participants performed a 30-min treadmill time trial (TT) followed by rehydration (0–2 hr) and refeeding (2–6 hr). Circulating leukocyte and lymphocyte counts remained unchanged for CON and FR. Circulating leukocyte, lymphocyte, CD3+, and CD4+ counts decreased by ~20% in ER and ~30% in F+ER by 48 hr (p < .01), returning to within 0-hr values by 6 hr post-TT. Circulating neutrophil count and degranulation were unaltered by dietary restriction at rest and after TT. In conclusion, a 48-hr period of ER and F+ER, but not FR, decreased circulating leukocyte, lymphocyte, CD3+, and CD4+ counts but not neutrophil count or degranulation. Circulating leukocyte and lymphocyte counts normalized on refeeding. Finally, dietary restriction did not alter circulating leukocyte, lymphocyte, and neutrophil responses to 30 min of maximal exercise.

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David C. Nieman, Giuseppe Valacchi, Laurel M. Wentz, Francesca Ferrara, Alessandra Pecorelli, Brittany Woodby, Camila A. Sakaguchi and Andrew Simonson

’s influence on exercise-induced changes in plasma cytokines and muscle and leukocyte cytokine mRNA . Journal of Applied Physiology, 103, 1728 – 1735 . doi:10.1152/japplphysiol.00707.2007 10.1152/japplphysiol.00707.2007 Nieman , D.C. , Henson , D.A. , Maxwell , K.R. , Williams , A.S. , McAnulty