Comparison of biomarkers of oxidative stress and cardiovascular disease in humans and chimpanzees (Pan troglodytes).

In the oxidative stress hypothesis of aging, the aging process is the result of cumulative damage by reactive oxygen species. Humans and chimpanzees are remarkably similar; but humans live twice as long as chimpanzees and therefore are believed to age at a slower rate. The purpose of this study was to compare biomarkers for cardiovascular disease, oxidative stress, and aging between male chimpanzees and humans. Compared with men, male chimpanzees were at increased risk for cardiovascular disease because of their significantly higher levels of fibrinogen, IGF1, insulin, lipoprotein a, and large high-density lipoproteins. Chimpanzees showed increased oxidative stress, measured as significantly higher levels of 5-hydroxymethyl-2-deoxyuridine and 8-iso-prostaglandin F(2alpha), a higher peroxidizability index, and higher levels of the prooxidants ceruloplasmin and copper. In addition, chimpanzees had decreased levels of antioxidants, including alpha- and beta-carotene, beta-cryptoxanthin, lycopene, and tocopherols, as well as decreased levels of the cardiovascular protection factors albumin and bilirubin. As predicted by the oxidative stress hypothesis of aging, male chimpanzees exhibit higher levels of oxidative stress and a much higher risk for cardiovascular disease, particularly cardiomyopathy, compared with men of equivalent age. Given these results, we hypothesize that the longer lifespan of humans is at least in part the result of greater antioxidant capacity and lower risk of cardiovascular disease associated with lower oxidative stress.

The risk of developing lung cancer associated with antioxidants in the blood: ascorbic acids, carotenoids, alpha-tocopherol, selenium, and total peroxyl radical absorbing capacity.

Lung cancer cases diagnosed during the period 1975 through 1993 and matched controls were identified in the rosters of Washington County, Maryland residents who had donated blood for a serum bank in 1974 or 1989. Plasma from participants in the 1989 project was assayed for ascorbic acid; serum or plasma was assayed for participants in either project for alpha- and beta-carotene, cryptoxanthin, lutein/zeaxanthin, lycopene, alpha-tocopherol, selenium, and peroxyl radical absorption capacity. Among the total group of 258 cases and 515 controls, serum/plasma concentrations were significantly lower among cases than controls for cryptoxanthin, beta-carotene, and lutein/zeaxanthin with case-control differences of -25.5, -17.1, and -10.1%, respectively. Modest nonsignificant case-control differences in a protective direction were noted for alpha-carotene and ascorbic acid. There were only trivial differences for lycopene, alpha-tocopherol, selenium, and peroxyl radical absorption capacity. Findings are reported for males and females and for persons who had never smoked cigarettes, former smokers, and current smokers at baseline. These results and those from previous studies suggest that beta-carotene is a marker for some protective factor(s) against lung cancer; that cryptoxanthin, alpha-carotene, and ascorbic acid need to be investigated further as potentially protective factors or associates of a protective factor; and that lycopene, alpha-tocopherol, selenium, and peroxyl radical absorption capacity are unlikely to be associated with lung cancer risk. Until specific preventive factors are identified, the best protection against lung cancer is still the avoidance of airborne carcinogens, especially tobacco smoke; second best is the consumption of a diet rich in fruits and vegetables.

Oxidative stress and aging: catalase is a longevity determinant enzyme.

Schriner and colleagues have reported an important advance in our understanding of the mechanisms controlling lifespan in mammalian species. A transgenic mouse strain was constructed (MCAT) with a C57BL/6J background that has about a 50-fold increase in expression in cardiac mitochondria and skeletal muscle of catalase enzyme activity. The MCAT strain was found to have reduced severity of age-dependent arteriosclerosis and increased genomic stability, as indicated by a decrease in oxidative stress and mitochondrial deletions in heart and muscle tissues. Most exciting, however, is that both median and maximum lifespan were increased about 17-21% compared to wild-type controls. It was disappointing that the Gompertz plot of the MCAT strain ran parallel to the wild-type control, indicating a delay in the onset of aging rather than a decrease in aging rate. Nevertheless, these results support the notion of a role for mitochondrial oxidative stress as a determinant of both healthspan and lifespan. In addition, the relatively large increase in lifespan resulting from upregulation of a single gene suggests the possibility that similar upregulation of relatively few key longevity determinant genes may result in dramatic increases in lifespan.

Oxidative stress profiling: part I. Its potential importance in the optimization of human health.

Steadily accumulating scientific evidence supports the general importance of oxidative damage of tissue and cellular components as a primary or secondary causative factor in many different human diseases and aging processes. Our goal has been to develop sensitive and reliable means to measure the oxidative damage and defense/repair status of an individual that could be easily used by a physician to determine whether there is an immediate or long-term increased health risk to their patients with regard to oxidative damage. We also sought to try to determine how this risk can best be reduced, and whether the prescribed therapy is working and how it might be best adjusted to optimize benefits. We have found that combining both an oxidative damage profile with a defense/repair profile produces the most reliable set of information to meet these objectives. Success is indicated by demonstrating the expected inverse correlation of oxidative stress vs. antioxidant status of a population of several hundred individuals. We also find support that oxidative stress status is under tight regulatory control for most individuals over a wide range of lifestyle variables including diet and exercise. Indeed only about 10% of the individuals analyzed appear to have unusually high oxidative stress levels. Only these individuals having the higher than normal levels of oxidative stress are the best responders to antioxidant supplements to lower their oxidative stress status to normal levels. We discuss the implications of these results for human application and review how current clinical studies are carried out to evaluate the benefits of antioxidant supplements in reducing the incidence of specific age-dependent disease.

Oxidative stress profiling: part II. Theory, technology, and practice.

Many of the most serious human diseases have a strong association with the steady-state level of oxidative damage in tissues. On an individual level this damage is defined as the patient's oxidative stress status (OSS). OSS is associated with many of the major age-related diseases such as cancer, heart disease, diabetes, and Alzheimer's disease, as well as with the aging process itself. In general, the greater the OSS of the individual, the higher the risk for disease development. To further understand the role that OSS has as a causative or an associated factor for these diseases, and to develop more effective personalized therapy to minimize OSS, requires a reliable means to measure the many different components contributing to an individual's OSS. This procedure is called oxidative stress profiling (OSP) and represents a new strategy to simultaneously assess an individual's OSS as well as to identify key physiological parameters, such as the hormone, lipid, antioxidant, or iron profile, that may be responsible for that individual's OSS. The OSP strategy provides physicians with information that enable them to make a more accurate diagnosis of the patient's condition and to recommend specific types of therapy based on better scientific data. Follow-up studies of the patient would then be conducted using these same tests until the OSS of the patient has been minimized. The OSP strategy is particularly well suited for a personalized health optimization program. The procedure is based on measuring both the steady-state levels of oxidative damage in nucleic acids, proteins, and lipids and the protective and defense processes of these components using blood, urine, and breath samples. Testing individuals before and after a controlled amount of exercise (70% VO2) may also help to obtain greater sensitivity and reproducibility. Evaluation of test results to obtain an integrated calculated OSS result for a patient represents a major challenge. One approach is to present the test results on a percentile bases, allowing results of different tests to be integrated into one or a few parameters, such as an oxidative stress and an antioxidant index. This article presents a general overview and rationale of the concept of the oxidative stress profile, tests to be used, and examples of how it may be applied.

Urinary excretion of three nucleic acid oxidation adducts and isoprostane F(2)alpha measured by liquid chromatography-mass spectrometry in smokers, ex-smokers, and nonsmokers.

To assess novel liquid chromatography/mass spectrometric methods for measuring oxidative damage to nucleic acids and lipids, we compared urinary excretion of 8-hydroxy-2'-deoxyguanosine (8-OHdG), 5-hydroxymethyl-2'-deoxyuridine (5-OHmU), and 8-hydroxyguanosine (8-OxoG), and an isoprostane, 8-iso-prostaglandin F(2)alpha (IsopF(2)alpha) in 234 healthy men (n = 113) and women (n = 121), 80 current smokers, 96 never-smokers), and 58 ex-smokers (no tobacco use for 3 years). The 8-OHdG and 8-OxoG did not differ significantly by group; 5-OHmU was higher in smokers, compared with ex- (p <.003) and never- (p <.0001) smokers and in ex- vs. never-smokers (p =.014) at, respectively, 13.5 +/- 0.7, 11.3 +/- 1.0, and 8.7 +/- 0.3 microg/g creatinine. IsopF(2)alpha was higher in smokers, compared with ex- (p =.007) and never-smokers (p <.0001) and in ex- vs. never- smokers (p =.002) at, respectively, 1.1 +/- 0.10; 0.74 +/- 0.07, and 0.51 +/- 0.04 microg/g creatinine. There were significant correlations among all three nucleic acid adducts and between IsopF(2)alpha and both 5-OHmU and 8-OHdG. Many smokers and ex-smokers had high levels of either 5-OHmU excretion or IsopF(2)alpha excretion, but not both. We conclude that 5-OHmU and IsopF(2)alpha are more discriminating of oxidative stress from tobacco smoke than the other two compounds measured. Whether characteristic patterns of excretion of these indicators forecast differential disease risk should be explored in future research.

The effect of caloric restriction on glycation and glycoxidation in skin collagen of nonhuman primates.

The accumulation of Maillard reaction products increases with age in long-lived proteins and can be retarded by caloric restriction. Here we determined whether caloric restriction inhibits formation of glycation and glycoxidation products in skin collagen of squirrel and rhesus monkeys between 1990-1997. Restricted monkeys (n = 11, n = 30, respectively) were maintained at 70% of caloric intake of controls (n = 25, n = 32, respectively). Glycation was assessed by furosine and glycoxidation by pentosidine and carboxymethyl-lysine. With age, the rate of furosine formation moderately but nonsignificantly (p >.05) increased in both control monkey groups. It significantly (p =.011) decreased in the caloric-restricted rhesus, but not squirrel monkeys. Caloric restriction did not significantly decrease the pentosidine or carboxymethyl-lysine rates in either species of monkeys. These results suggest that caloric restriction, when maintained long-term in nonhuman primates, tends to decrease glycation, but not glycoxidation.

Quantification of 8-iso-prostaglandin-F(2alpha) and 2,3-dinor-8-iso-prostaglandin-F(2alpha) in human urine using liquid chromatography-tandem mass spectrometry.

Quantification of 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) has been suggested to be a reliable indicator of lipid peroxidation that may be related to in vivo free radical generation, oxidative damage, and antioxidant deficiency. We have developed a LC-MS/MS method to quantify 8-iso- PGF(2alpha) and its dinor metabolite, 2,3-dinor-8-iso-prostaglandin F(2alpha) (2,3-dinor-8-iso-PGF(2alpha)), in human urine samples. After an initial purification step using an automated C18 solid phase extraction procedure, the urine sample was injected directly into a liquid chromatography (LC) system and detected with tandem mass spectrometry. The detection limit of the assay was 9 pg for 8-iso-PGF(2alpha) and 3 pg for 2,3-dinor-8-iso-PGF(2alpha) with both inter- and intraday variations of less than 12%. The inaccuracies were less than 3% for both analytes at three different levels. The urinary excretion rate of 2,3-dinor-8-iso-PGF(2alpha) was higher than that of 8-iso-PGF(2alpha), and changed in proportion to the parent compound (R = 0.70, n = 60). Values obtained with this method showed good linear correlation to duplicate 8-iso-PGF(2alpha) measurements performed with GCMS (R = 0.97, n = 15). The mean excretion rates of 8-iso-PGF(2alpha) and 2,3-dinor-8-iso-PGF(2alpha) were significantly higher in smokers than in nonsmokers (0.53 +/- 0.37 vs. 0.25 +/- 0.15 microg/g creatinine, p = 0.002 for 8-iso-PGF(2alpha) and 8.9 +/- 3.8 vs. 4.6 +/- 2.6 microg/g creatinine, p = 0.003 for 2,3-dinor-8-iso-PGF(2alpha), respectively). The excellent accuracy, reproducibility, and high throughput of this method should permit it to be used in large clinical studies and standard clinical laboratories.

Measures of body size and growth in rhesus and squirrel monkeys subjected to long-term dietary restriction.

Although many studies have reported the robust effects of dietary restriction (DR) in retarding numerous aging processes in rodents, little is known about the outcomes of reducing caloric intake of a nutritious diet on aging in primates. Most primate studies have concerned the effects of malnutrition. We hypothesized that DR influences aging processes in primate species as it does in rodents. In the present study, 24 male rhesus (Macaca mulatta) monkeys (ages 0.6-5 years) and 25 male squirrel (Saimiri sp.) monkeys (ages 0.3-10 years) were provided diets formulated differently for each species but both fortified with vitamins and minerals (40% above recommended levels) as controls (approximating ad libitum levels) or experimentals (about 30% below the level of diet provided controls of comparable age and body weight). The results reported here concern the hypothesis that DR imposed during various developmental stages in these two primate species would affect morphometric parameters obtained at different occasions during the first 5 years of the study. Groups of older monkeys (rhesus: 18-25 years, n = 3; squirrel: 10-15 years, n = 4) were also included as controls for comparative purposes. Among groups of rhesus monkeys begun on DR prior to 6 years of age, growth in body weight and crown-rump length was reduced about 10-20% beginning after 1 year on the diet, with estimated food intake being reduced about 30-35% over this period. Measures of skin-fold thickness and various body circumference measures were also reduced in experimental groups of rhesus monkeys. In contrast, the DR regimen involving a different diet produced little impact on comparable measures in squirrel monkeys, with the estimated food intake being reduced only about 20-25% over this period. However evidence of divergence in some morphometric parameters in squirrel monkeys was beginning to emerge in young groups (<5 years(after 3 yers on the diet. © 1995 Wiley-Liss, Inc.