Sustained strenuous exercise in sled dogs depresses three blood copper enzyme activities.

Studies show mixed conclusions about acute responses of copper status to strenuous exercise. Because copper function involves metalloenzyme activities, which might take days to change, the present study examined the response of three copper metalloenzyme activities to sustained strenuous exercise in sled dogs. A race lasting 12-15 d depressed activities for both plasma ceruloplasmin and erythrocyte superoxide dismutase in dogs consuming commercial dog foods and meats. A shorter, 3-d training run for dogs fed a commercial balanced diet also depressed ceruloplasmin activities but not superoxide dismutase activities. Dogs fed the same diet but that did not run showed no changes in either parameter. Activities of a third copper enzyme, plasma diamine oxidase, also decreased after a 3-d training run. In summary, blood activities of three copper enzymes were depressed by sustained strenuous exercise in sled dogs.

Soy intake plus moderate weight resistance exercise: effects on serum concentrations of lipid peroxides in young adult women.

AIM: Exercise can conceivably increase concentrations of lipid peroxides (by producing oxidant stress) or decrease their concentrations (by accelerating peroxide breakdown). The net effect could depend on exercise intensity and nutritional antioxidant intake. METHODS: Recreationally trained, young adult women (n=18) consumed antioxidant-rich soy protein or antioxidant-poor whey protein for 4 weeks (40 g protein/day). A moderate intensity, weight resistance exercise session was done before and after the 4 week period. Blood was drawn before each exercise session and postexercise at 0, 3 and 24 h. Serum from the pre-exercise draw was analyzed for antioxidant status (based on radical scavenging capacities); serum from pre- and postexercise draws were analyzed for concentrations of lipid peroxides as well as creatine kinase activities (which are affected by oxidant damage to muscles). RESULTS: Soy, but not whey intake, increased pre-exercise serum antioxidant status values and inhibited exercise-induced increases in creatine kinase activities. Before soy or whey intake, serum values for lipid peroxides rose at two of the three postexercise times. After whey intake, values for lipid peroxides showed no increase at the three postexercise times. After soy treatment, values for lipid peroxides actually showed a decrease at the three postexercise times. CONCLUSIONS: Moderate intensity exercise exerted variable effects on serum lipid peroxides with decreases occurring with 4 weeks of soy intake, which also produced other antioxidant effects.

Association between vitamin E and enhanced athletic performance in sled dogs.

PURPOSE: To determine the association between prerace plasma vitamin E concentration and performance in sled dogs competing in the 1998 Iditarod Race. METHODS: Prerace blood samples were collected from 670 dogs. Samples were analyzed for plasma vitamin E concentration while controlling for selected hematological and biochemical variables and signalment. Starting in teams of 16, exercise consisted of running up to 1159 miles pulling a laden sled and musher via checkpoints. The records of dogs that were withdrawn from the race for health reasons, fatigue, or strategic or technical reasons, and those of dogs that finished the race were analyzed. Multiple logistic regression and Cox proportional hazards analysis were used to determine factors associated with endurance. Multiple linear regression analysis was used to determine factors associated with team speed. RESULTS: A total of 323 dogs (48%) were withdrawn from racing at various distances from the start. Median time to finish for 39 teams was 11.5 d and the winning time was 9.2 d. Dogs with prerace plasma vitamin E concentrations > 40.7 microg.mL-1 were 1.9 times more likely to finish (P = 0.0006) and had 1.8 times less of a risk of being withdrawn for every mile ran (P = 0.03) than were dogs with plasma vitamin E concentrations between 16.3 and 40.7 microg.mL-1. Neither a team's mean prerace vitamin E concentration, nor the proportion of dogs within a team with high (> 40.7 microg.mL-1) vitamin E concentration was associated with team speed. CONCLUSIONS: Dogs with higher plasma vitamin E concentrations have enhanced endurance compared with dogs with lower plasma vitamin E concentrations, but the plasma vitamin E status of a team is not associated with team speed.

Vitamin E and exertional rhabdomyolysis during endurance sled dog racing.

Exertional rhabdomyolysis (ER) is common in sled dogs, animals with high energy expenditures that consume high fat (60% of ingested calories) diets. Associations between pre-race plasma [vitamin E] and total antioxidant status (TAS) and risk of developing ER were examined in dogs competing in the 1998 Iditarod race. Pre-race blood samples were collected from 750 dogs and a second sample was collected from 158 dogs withdrawn from the race at various times. Plasma creatine kinase activity was used to identify withdrawn dogs with ER. There was no association between pre-race plasma [vitamin E] and risk of development of ER. Dogs that developed ER started the race with higher TAS, but when withdrawn, had lower TAS than unaffected dogs and had similar pre-race [vitamin E] but higher [vitamin E] at time of withdrawal. Hence, the risk of ER in sled dogs is not affected by plasma [vitamin E] before the race.

Effect of dietary supplements containing antioxidants on attenuation of muscle damage in exercising sled dogs.

OBJECTIVE: To determine whether dietary antioxidants would attenuate exercise-induced increases in plasma creatine kinase (CK) activity in sled dogs. ANIMALS: 41 trained adult sled dogs. PROCEDURE: Dogs, randomly assigned to 2 groups, received the same base diet throughout the study. After 8 weeks on that diet, 1 group (21 dogs) received a daily supplement containing vitamins E (457 U) and C (706 mg) and beta-carotene (5.1 mg), and a control group (20 dogs) received a supplement containing minimal amounts of antioxidants. After 3 weeks, both groups performed identical endurance exercise on each of 3 days. Blood samples were collected before and 3 weeks after addition of supplements and after each day of exercise. Plasma was analyzed for vitamins E and C, retinol, uric acid, triglyceride, and cholesterol concentrations, total antioxidant status (TAS), and CK activity. RESULTS: Feeding supplements containing antioxidants caused a significant increase in vitamin E concentration but did not change retinol or vitamin C concentrations orTAS. Exercise caused significantly higher CK activity, but did not cause a significant difference in CK activity between groups. Exercise was associated with significantly lower vitamin E, retinol, and cholesterol concentrations and TAS but significantly higher vitamin C, triglyceride, and uric acid concentrations in both groups. CONCLUSIONS AND CLINICAL RELEVANCE: Use of supplements containing the doses of antioxidants used here failed to attenuate exercise-induced increases in CK activity. Muscle damage in sled dogs, as measured by plasma CK activity, may be caused by a mechanism other than oxidant stress.

Effects of dietary antioxidant supplementation on oxidative damage and resistance to oxidative damage during prolonged exercise in sled dogs.

OBJECTIVES: To determine effects of dietary antioxidant supplementation on plasma concentrations of antioxidants, exercise-induced oxidative damage, and resistance to oxidative damage during exercise in Alaskan sled dogs. ANIMALS: 62 Alaskan sled dogs. PROCEDURE: Dogs were matched for age, sex, and ability and assigned to 1 of 3 groups: sedentary and nonsupplemented (control [C]; n = 21), exercised and supplemented (S; 22), and exercised and nonsupplemented (N; 19). Dogs in group S were given 400 units of alpha-tocopherol acetate, 3 mg of beta-carotene, and 20 mg of lutein orally per day for 1 month, then dogs in groups S and N completed 3 days of exercise. Blood samples were collected before and after 1 and 3 days of exercise and after 3 days of rest. Plasma antioxidant concentrations were determined, and oxidative damage to DNA (plasma 7,8 dihydro-8-oxo-2'deoxyguanosine [8-oxodG] concentration) and membrane lipids (plasma hydroperoxide concentration) and resistance of plasma lipoproteins to oxidation were assessed. RESULTS: Supplementation increased plasma concentrations of alpha-tocopherol, beta-carotene, and lutein. Plasma concentration of alpha-tocopherol increased and concentration of lutein decreased in group S with exercise. Concentration of 8-oxodG decreased in group S but increased in group N during and after exercise. Lag time of in vitro oxidation of lipoprotein particles increased with exercise in group S only. CONCLUSIONS AND CLINICAL RELEVANCE: Dietary supplementation with antioxidants resulted in increased plasma concentrations of antioxidants. Moreover, supplementation decreased DNA oxidation and increased resistance of lipoprotein particles to in vitro oxidation. Antioxidant supplementation of sled dogs may attenuate exercise-induced oxidative damage.

Zinc in relation to diabetes and oxidative disease.

Theoretically, zinc can exert a number of indirect antioxidant functions. Researchers at our laboratory have found evidence to support this concept by studying mild zinc deficiency in rats. This state produces low resistance to chemically induced liver oxidant injury, and it produces high vulnerability of lipoproteins to oxidation. We are building on this work in rats to test a hypothesis in humans that increased zinc intake will protect against oxidant stress in persons with tendencies for both moderate zinc deficiency and high oxidant stress. This hypothesis has been tested in postmenopausal, type 2 diabetic women. A 3-wk supplementation with zinc (30 mg/d as glycine-chelate) raised initially low plasma zinc values to above normal values and increased plasma activities of 5'-nucleotidase. However, the latter values were still well below normal. Lipoprotein oxidation tendencies, a measure of oxidant stress, were not altered by the zinc treatment. A new project has been initiated to determine whether both a higher dose and longer duration of zinc treatment will normalize 5'-nucleotidase activities and affect the indices of oxidant stress. The latter will be considered in terms of both zinc supplementation and supplementation of zinc plus vitamin C, another problem nutrient for diabetic persons.

Short term citrus flavonoid supplementation of type II diabetic women: no effect on lipoprotein oxidation tendencies.

Flavonoids, which are dietary components and have possible drug uses, inhibit lipoprotein oxidation in vitro. The present study considered whether flavonoid supplementation in humans could influence lipoprotein vulnerability to oxidation. Citrus flavonoid supplementation (about 1g/day, 3 weeks), or placebo, was given to 40 Type II diabetic women, a population prone to oxidative stress. Absorbance spectra of plasma from 4 subjects revealed that some flavonoid absorption occurred. When tested in vitro, a supplement extract, with spectrum peak height similar to that of plasma samples, completely inhibited copper-induced oxidation of very low plus low density lipoproteins. In contrast, neither flavonoid supplementation nor placebo influenced lipoprotein susceptibility to copper-stimulated oxidation in vitro (lag time or propagation rate). Thus, this study demonstrated that increased flavonoid consumption by humans does not necessarily alter lipoprotein susceptibility to oxidation assessed in vitro.

Antioxidant enzyme activity in human abdominal aortic aneurysmal and occlusive disease.

The present study further investigates evidence for lipid peroxidation in atherosclerotic aortic tissue by determining the activity of antioxidant enzymes and concentrations of lipid peroxide fluorochromes in abdominal aortas from 15 patients with abdominal aortic aneurysms (AAA), an additional 7 patients with ruptured abdominal aneurysms, and 12 patients with atherosclerotic occlusive disease (AOD). Aortas from nonatherosclerotic organ donors served as nondiseased controls. Cu, Zn-superoxide dismutase (Cu,Zn-SOD) activities in AAA and AOD tissues were 16% and 25% of control activity, respectively. Mn-SOD activity in diseased aortae were about 65% of controls. CuZn-SOD protein in AAA and AOD was 56% and 100% of controls, respectively, resulting in significantly lower CuZn-SOD specific activity in these tissues. Ruptured AAA tissue also had low SOD activity and protein. Glutathione peroxidase (GPx) activity in AAA and AOD aortas was 70% and 65% of controls, respectively, and glutathione reductase (GR) activity in AAA and AOD aortas was 80% and 65% of control activities, respectively. These results were associated with significantly higher lipid peroxide fluorochromes, expressed as U/g aorta, in both groups of atherosclerotic aortas than in controls. AOD aortas had 33% higher fluorescence than AAA aortas, but the highest levels were seen in ruptured AAA. These data further support the involvement of free radicals and lipid peroxidation in atherosclerotic aortic disease, but do not indicate that these mechanisms are specifically involved in aneurysm formation versus development of occlusive disease.

No effects of low copper intake on rat mammary tissue superoxide dismutase 1 activity and mammary chemical carcinogenesis.

Variations in copper-containing superoxide dismutase (SOD) 1 are hypothesized to produce variations in resistance to carcinogenesis, particularly in mammary tissue. Therefore, it is reasonable to speculate that low copper intake, which causes low SOD 1 activities in various tissues, would cause poor resistance to mammary carcinogenesis. This idea was tested using female rats fed diets either low or adequate in copper (< 0.5 or 8 mg copper/kg diet) plus or minus oral gavage with the mammary carcinogen 7,12-dimethylbenz[a]anthracene (5 mg/kg, given 5 wk after dietary modification, 28 wk before sacrifice). Low copper intake produced low activities of two serum copper enzymes: ceruloplasmin and extracellular SOD. In contrast, low copper intake did not affect mammary tissue SOD 1 activities, nor did it statistically influence any of several parameters of 7,12-dimethylbenz[a]anthracene-induced mammary carcinogenesis.

BAL fluid contains detectable superoxide dismutase 1 activity.

OBJECTIVE: This study determined which, if any, of the three superoxide dismutase (SOD) enzyme activities were detectable in BAL fluid (BALF). BACKGROUND: The identity and concentrations of antioxidant molecules in BALF have not been fully characterized. One important class of antioxidants is that of the SOD enzymes. METHODS: BALF from control nonsmokers (n=9), smokers (n=7), and asthmatic subjects (n=12) were examined for SOD activity by a modified pyrogallol auto-oxidation method. The particular SOD enzyme or enzymes responsible for any activity were identified based on activity inhibition data and gel filtration column chromatography patterns. RESULTS: SOD activity was detected in all samples. Unlike serum or some other fluids, in which the enzyme extracellular SOD accounts for virtually all SOD activity, the enzyme SOD 1 accounted for virtually all SOD activity. BALF SOD activities were lower for smokers than for control or asthmatic subjects (p<0.05). CONCLUSION: BALF SOD 1 activities can be measured as part of lung antioxidant studies. Data from a limited number of subjects suggested that smokers can have low BALF SOD values.

Plasma diamine oxidase activities in renal dialysis patients, a human with spontaneous copper deficiency and marginally copper deficient rats.

OBJECTIVES: Intestine and kidney are generally the most concentrated sources of the copper metalloenzyme diamine oxidase (DAO). Clinically, plasma DAO activities are used to diagnose disruptions in intestinal integrity. This study determined whether DAO activities were also affected by kidney injury or copper nutritional status. DESIGN AND METHODS: Plasma DAO activities were measured in renal dialysis patients without diagnosed intestinal disease (n = 75), controls (n = 23), an adult with spontaneous copper deficiency before and after copper repletions, and in rats fed either adequate or marginal copper diets (8 or 2 mg copper/kg diet) for 7 months. RESULTS: This study found high DAO activities in renal dialysis patients and low activities during spontaneous copper deficiency. Low activities were also seen for marginally copper deficient rats. CONCLUSIONS: Tissue injury-induced elevation of DAO activities is not limited to intestinal injury, and low DAO values may be useful for assessing copper nutritional status.

Short-term zinc supplementation in women with non-insulin-dependent diabetes mellitus: effects on plasma 5'-nucleotidase activities, insulin-like growth factor I concentrations, and lipoprotein oxidation rates in vitro.

Non-insulin-dependent diabetes mellitus (NIDDM) may cause vulnerability to moderate zinc deficiency. In this study, short-term zinc supplementation (30 mg/d as amino acid chelate for 3 wk) elevated plasma zinc and activities of 5'-nucleotidase, a zinc-dependant enzyme, in 20 postmenopausal women with NIDDM. Placebo, given to 20 other women with NIDDM, had no effects on these indexes nor on any others taken in this study. Although zinc supplementation doubled the mean value for 5'-nucleotidase activity, values were still significantly lower than those of age-matched control subjects. Plasma insulin-like growth factor I concentrations increased with zinc treatment if starting concentrations were < 165 microg/L but were unchanged if they were > 165 microg/L. Lipoprotein oxidation in vitro, which has abnormal lag times and propagation rates for subjects with NIDDM and for moderately zinc-deficient rats, were unchanged by zinc supplementation. Possibly, this lack of effect occurred because the zinc treatment did not normalize zinc status. In conclusion, this study supports the contention that moderate zinc deficiency occurs frequently in subjects with NIDDM.

Moderate zinc deficiency in rats enhances lipoprotein oxidation in vitro.

Zinc inhibits low density lipoprotein oxidation in vitro. This observation and others provide indirect evidence that Zn affects radical-mediated processes. This study demonstrated that moderate Zn deficiency in rats produced very low and low density lipoproteins with abnormally high sensitivity to copper-catalyzed oxidation in vitro (short lag time, high propagation rate). The amount of Zn in the oxidation assay did not appear to contribute to the results. Because lipoprotein oxidation in vitro seems to reflect certain oxidative processes in vivo, this study strengthened the contention that Zn affects radical-mediated damage in vivo.

Comparison of Zn and vitamin E for protection against hyperoxia-induced lung damage.

The objective of the present study was to demonstrate an antioxidant function for Zn in vivo by comparing the efficacy of Zn or Vitamin E without additional energy intake for protection of Zn-deficient (ZnDF) or energy-restricted (ER) rats from hyperoxia-induced lung damage. Zn (200 mumol ZnCl2/kg b.wt.) or Vitamin E (100 mg alpha-tocopherol/kg b.wt.) was injected IP before exposure to 85% oxygen or air for 5 d. During the exposure period, all injected ZnDF or ER rats were restricted to 5 g Zn-deficient or Zn-adequate diet/day, respectively, the amount of diet consumed by the untreated ZnDF or ER rats. We clearly demonstrated that injection of Zn without additional energy intake can protect ZnDF and ER rats from hyperoxia-induced lung damage assessed by the histopathological scoring system and magnetic resonance imaging (MRI). Vitamin E was not as effective as Zn in either ZnDF or ER rats for preventing hyperoxia-induced lung damage. Zn injection did not exert its antioxidant effect through increased lung CuZn-superoxide dismutase activity or metallothionein. This difference in the effectiveness of Vitamin E and Zn for hyperoxic protection in lung injury may be due to the specificity of antioxidant function, i.e., vitamin E inhibits oxidation of membrane lipids and Zn protects sulfhydryl groups of proteins.

Copper supplementation of adult men: effects on blood copper enzyme activities and indicators of cardiovascular disease risk.

In rats, copper deficiency leads to low copper metalloenzyme activity, high serum cholesterol, and cardiovascular lesions. In humans, moderately low copper intake may be common, but the consequences remain largely uncertain. The present study examined the effects of copper supplementation (2 mg/d for 4 weeks in a copper/placebo crossover design) in 20 adult men with moderately high plasma cholesterol. End-point measurements were three copper enzyme activities, erythrocyte superoxide dismutase (SOD), plasma ceruloplasmin (Cp), and plasma diamine oxidase (DAO), and three parameters related to the risk of cardiovascular disease (CVD), plasma cholesterol, plasma lipoprotein (a) [Lp(a)], and lag times for very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) oxidation in vitro. Although copper had no significant effects on any parameter for the entire study group, it did significantly increase two enzyme activities (SOD and DAO), as well as lipoprotein oxidation lag times, in 10 subjects in the lower half of a median split for precopper values. Thus, copper supplementation appeared to influence some types of measurements in subjects beginning with less than median values.

High ceruloplasmin levels in rats without high lipoprotein oxidation rates.

The serum copper protein ceruloplasmin, though sometimes considered an antioxidant, can promote lipoprotein oxidation in vitro under certain conditions. However, an inflammation-induced, two week elevation of rat serum ceruloplasmin levels did not render low plus very low density lipoproteins more prone to oxidation in vitro. Thus, high ceruloplasmin levels in vivo are not necessarily associated with high lipoprotein oxidation rates.

Copper-related blood indexes in kidney dialysis patients.

Previous work has suggested that kidney hemodialysis patients could be at risk for either moderate copper deficiency or copper toxicity. The present study examined copper-related blood indexes in subjects undergoing hemodialysis treatments with membranes that are not copper-based, in subjects undergoing chronic ambulatory peritoneal dialysis (CAPD), and in control subjects. Both dialysis groups had low plasma copper and ceruloplasmin activities. This occurred despite high plasma interleukin 6 concentrations, a situation that usually elevates plasma ceruloplasmin and copper values. CAPD and hemodialysis subjects had low ratios of ceruloplasmin activity to immunoreactive protein, and low ratios of plasma copper to ceruloplasmin protein. Both are signs of copper deficiency. In contrast, copper-containing erythrocyte superoxide dismutase (SOD) activities were high in hemodialysis subjects and showed a nonsignificant trend toward high values in CAPD subjects. Blood mononuclear cell copper contents were highly variable within each group, and there were no significant differences between groups. In conclusion, ceruloplasmin-related indexes in kidney dialysis patients not dialyzed with copper-based membranes suggested a tendency toward moderate copper deficiency. However, this contention could not be confirmed by erythrocyte SOD activity or mononuclear cell copper measurements.

Transgenic mice overexpressing metallothionein are not resistant to adriamycin cardiotoxicity.

Metallothionein (MT) induction, particularly by bismuth, is proposed to protect against toxic side effects of chemotherapy drugs such as adriamycin. In contrast, transgenic mice, which overexpressed cardiac MT, and also had moderately high heart glutathione concentrations, were not resistant to adriamycin-induced cardiotoxicity. Cardiotoxicity was assessed by survival, fluid accumulation and lipid peroxidation. Thus, higher than normal heart MT concentrations do not necessarily protect against adriamycin cardiotoxicity.

Changes in patients' taste acuity after Roux-en-Y gastric bypass for clinically severe obesity.

OBJECTIVE: Patients who have undergone Roux-en-Y gastric bypass (RYGB) for clinically severe obesity often report an aversion to sweet foods and meat. This study was designed to determine whether changes in taste acuity occur after RYGB. DESIGN: This prospective, repeated measures trial evaluated acuity for sweet (sucrose) and bitter (urea) tastes, zinc status, and reported changes in taste perceptions in patients undergoing RYGB for weight reduction. SUBJECTS: Taste acuity and serum zinc level were measured in 14 subjects, 6 men and 8 women (mean preoperative body mass index [calculated as kg/m2] = 60.8 +/- 11.8 and mean age = 38.4 +/- 6 years), before surgery and 6 and 12 weeks after surgery. Inquiries regarding taste preferences were made at each postoperative visit with specific reference to sweets and meat. Serum zinc level was measured at the same visit. A noncontrolled comparison group of 4 subjects who were consuming a very-low-calorie diet also underwent taste acuity testing at similar intervals. MAIN OUTCOME MEASURES: The main outcome measures were recognition taste thresholds, serum zinc levels, and taste preference changes. STATISTICAL ANALYSIS: Analysis of variance with repeated measures over time, Pearson correlation coefficients, and post hoc analysis of variance were used to analyze data. RESULTS: Mean recognition thresholds for sucrose were 0.047 +/- 0.03 mol/L preoperatively and fell significantly to 0.024 +/- 0.01 and 0.019 +/- 0.01 mol/L at 6 and 12 weeks postoperatively, respectively. Overall, there were no significant differences in taste thresholds for urea over time; a significant difference was noted, however, in the pattern of change for urea between patients who reported an aversion to meats and those who did not. Zinc concentrations did not change during the study. APPLICATION/CONCLUSIONS: At 6 weeks postoperatively, all patients reported that foods tasted sweeter, and they modified food selection accordingly. Six patients reported an aversion to meats associated with increased nausea and vomiting. Acuity for sweet and bitter tastes may need to be considered when planning dietary modifications for patients undergoing RYGB.