Maurice J. Weidemann

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.

Reactive oxygen production associated with arachidonic acid metabolism by peritoneal macrophages.

The nature of the calcium-dependent chemiluminescence observed in peritoneal macrophages after exposure to the calcium ionophore A23187 or during the phagocytosis of zymosan has been investigated. Eicosatetraynoic acid, an inhibitor of the lipoxygenase and cyclooxygenase pathways of arachidonic acid metabolism, inhibited the calcium-dependent chemiluminescence whereas indomethacin, a selective inhibitor of the cyclooxygenase pathway, did not. Arachidonic acid induced chemiluminescence only in phagocytosing cells, whilst 15-HPETE, an intermediate of the lipoxygenase pathway, generated a similar, transient chemiluminescent response in either unstimulated or phagocytosing cells. The results suggest that the lipoxygenase pathway may be a significant source of the reactive species of oxygen that give rise to chemiluminescence. Prostaglandin E1 inhibited the chemiluminescence induced by zymosan and A23187, but did not affect that generated in response to 15-HPETE or arachidonic acid, suggesting that the inhibition is directed at a step either connected with or occurring prior to the release of free arachidonic acid by the cells.

Phytohaemagglutinin stimulation of rat thymus lymphocyte glycolysis

Glucose disappearance and lactate production by the rat thymocytes are stimulated significantly 45 min after addition of phytohaemagglutinin or concanavalin A and the stimulated rate is sustained for at least 8 h. Changes in the steady-state concentration of glycolytic intermediates that occur at non-equilibrium steps during the increased rate of glycolytic flux indicate that the glucose carrier, hexokinase and phosphofructokinase are potentially regulatory steps that undergo nearly simultaneous or tightly sequential activation following interaction of the cells with the mitogen.

Neutrophil oxidative activity is differentially affected by exercise intensity and type

The differential effects of exercise intensity and type on neutrophil activation were assessed in eight well-trained male runners. Each subject undertook, on different days, three separate 40 min interval (8 x 5 min) treadmill bouts: an intense uphill run (90% VO2 max), a moderate-intensity near-level run and an eccentrically-biased downhill run (both at 52% VO2 max). Blood granulocyte count increased (p< 0.05) after all three treadmill bouts (range 25-108%). Chemiluminescence activity of isolated neutrophils decreased (p< 0.05) immediately after (-58%) and 1-h after (-72%) uphill running, but became significantly elevated (p< 0.05) at 6-h after the near-level (+71%) and downhill (+84%) runs. The ability of neutrophils to release the superoxide anion radical was reduced (p< 0.05) immediately after near-level (-29%) and uphill (-21%) running in cells stimulated with opsonized zymosan. Epinephrine concentration increased by 430% (p=0.01) after uphill but not with near-level or downhill running. The plasma concentration of elastase increased (p< 0.05) immediately after uphill and near-level running, and one hour after uphill running. These results suggest that a population of neutrophils mobilised into the circulation became directly activated in response to exercise, and that neutrophil oxidative activity is affected differentially by both the intensity and type of exercise undertaken.

Characterization of an [125I]-Insulin binding plasma membrane fraction from rat liver

Abstract A procedure for the isolation of three different plasma membrane fractions from rat liver is described. The heavy subfraction (PL1) has a high specific activity in alkaline phosphatase, while the lightest subfraction (PL3) contains a high specific activity in 5′-Nucleotidase, ATPase and phosphodiesterase. The major part of the plasma membrane recovered is found in PL3. A specific binding of [125I]-Insulin is shown to occur in PL3, with a ten-fold enhancement over that of any other plasma membrane fraction.

Changes in the susceptibility of red blood cells to oxidative and osmotic stress following submaximal exercise.

AbstractRed blood cell (RBC) susceptibility to oxidative and osmotic stress in vitro was investigated in cells from trained and untrained men before and after submaximal exercise. Whilst no significant change in peroxidative haemolysis occurred immediately after 1 h of cycling at 60% of maximal aerobic capacity (

Protection of vitamin E from oxidation by increased ascorbic acid content within Plasmodium vinckei-infected erythrocytes

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Reactive oxygen production, arachidonate metabolism and cyclic AMP in macrophages

max), a 20% increase was found 6 h later in both groups (P<0.05). The RBC osmotic fragility decreased by 15% immediately after exercise (P<0.001) and this was maintained for 6 h (Ps<0.001). There was an associated decrease in mean cell volume (P<0.05). Training decreased RBC susceptibility to peroxidative haemolysis (P<0.025) but it did not influence any other parameter. These exercise-induced changes were smaller in magnitude but qualitatively similar to those found in haemopathological states involving haem-iron incorporation into membrane lipids and the short-circuiting of antioxidant protection. To explore this similarity, a more strenuous and mechanically stressful exercise test was used. Running at 75%