The possibility that plasma levels of malonaldehyde (MDA) are altered by exercise has been examined. The presence of MDA has been recognized to reflect peroxidation of lipids resulting from reactions with free radicals. Maximal exercise, eliciting 100% of maximal oxygen consumption (VO2max) resulted in a 26% increase in plasma MDA (P less than 0.005). Short periods of intermittent exercise, the intensity of which was varied, indicated a correlation between lactate and MDA (r2 = 0.51) (p less than 0.001). Blood lactate concentrations increased throughout this exercise regimen. A significant decrease (10.3%) in plasma MDA occurred at 40% VO2max. At 70% VO2max plasma MDA was still below resting values, however the trend to an increase in MDA with exercise intensity was evident. At exhaustion, plasma MDA and lactate were significantly greater than at rest. These results suggest, that exhaustive maximal exercise induces free radical generation while short periods of submaximal exercise (i.e. less than 70% VO2max) may inhibit it and lipid peroxidation.

Research U pper respiratory tract infections are a major source of morbidity throughout the world; in the United States alone at least 1 billion colds per year have been reported, with a frequency of 2-6 colds per person. 1 Finding effective ways to reduce the frequency of these infections is therefore an important issue. Agents such as analgesics, antihistamines and decongestants have been found to be ineffective because of their limited efficacy against specific symptoms, 2 whereas safety concerns for some antiviral drugs limit their use. 3,4 Natural health products with properties that stimulate the immune system have been used to combat the common cold, but the results are often inconsistent. 5 Extracts of North American ginseng (Panax quinquefolium) containing polysaccharides and oligosaccharides have been shown to have immunomodulatory effects. [6][7][8][9][10][11][12] These extracts have been shown to enhance immune responses such as immunoglobulin production by lymphocytes and natural immune responses by peritoneal exudate macrophages. 6 They have also been found to enhance anticomplementary and reticuloendothelial system activities, 7 enhance macrophage Fc receptor expression, 8 increase the phagocytosis index along with phagocytosis fraction, 9 and induce messenger RNA expression of interleukin-2 (IL-2), interferongamma (IFN-γ), interleukin-1α and granulocyte-macrophage colony-stimulating factor as well as lymphokine-activated killer cells and CD8+ cells. 10 In addition, these extracts appear to stimulate cell-mediated immune response and natural killer cell cytotoxicity 11 as well as to have cytotoxic effects on a wide range of tumour cell lines without major histocompatibility complex restriction. 12 Recently, a patented poly-furanosyl-pyranosyl-saccharide-rich extract of North American ginseng (COLD-fX, CV Technologies Inc., Edmonton) was also shown to be capable of enhancing lymphocyte function and initiating acquired immune responses. 13 In a recent study on human peripheral blood mononuclear cells cultured with live influenza virus, the extract was shown to be effective in enhancing the production of IL-2 and IFN-γ (unpublished data). IL-2 and IFN-γ are major T-cell and natural killer cell cytokine responses associated with virus-elicited adaptive immunity, and IFN-γ

Early intervention with a standardized formulation of echinacea resulted in reduced symptom severity in subjects with naturally acquired upper respiratory tract infection. Further studies with larger patient populations appear to be warranted.

In a previous paper, it was reported that Echinilin (Factors R & D Technologies, Burnaby, British Columbia, Canada) a formulation prepared from freshly harvested Echinacea purpurea plants and standardized on the basis of three known active components (alkamides, cichoric acid and polysaccharides) is effective for the treatment of a naturally acquired common cold. However, the mechanism by which this effect is achieved remains unknown. In the present study, Echinilin or placebo were administered to volunteers at the onset of their cold for a period of 7 days, with eight doses (5 mL/dose) on day 1 and three doses on subsequent days. Fasting blood samples were obtained before and during their colds. The decrease in total daily symptomatic score was more evident in the echinacea group than in the placebo group. These effects of echinacea were associated with a significant and sustained increase in the number of circulating total white blood cells, monocytes, neutrophils and NK cells. In the later part of the cold, the echinacea treatment suppressed the cold-related increase in superoxide production by the neutrophils. These results suggest that Echinilin, by enhancing the non-specific immune response and eliciting free radical scavenging properties, may have led to a faster resolution of the cold symptoms.

This study examined the acute effects of oral inhalation of 10-ppm hydrogen sulfide (H2S) inhalation (a concentration equal to its occupational exposure limit) on the pulmonary function in healthy men and women. Nine men and ten women consented to inhale medical air or 10 ppm H2S for 15 minutes each during cycle exercise at 50% of their maximal aerobic power. Routine pulmonary function tests were administered at rest and immediately after the two exposure conditions. The results indicated no significant changes in any of the variables derived from the flow volume loop, maximum ventilation volume, and diffusion capacity of the lung for carbon monoxide in both genders. None of the subjects experienced any signs and symptoms as a result of H2S exposure. It was concluded that oral inhalation of 10 ppm H2S at an elevated metabolic and ventilation rate does not significantly alter pulmonary function in healthy men and women.