Oxidative DNA damage levels in blood from women at high risk for breast cancer are associated with dietary intakes of meats, vegetables, and fruits

Pros & cons of some popular extreme weight-loss diets

Obesity has now become a huge public health issue not only in the developed world but also in developing countries. In view of the health hazards associated with obesity and more importantly for cosmetic reasons, many people, particularly the youth, have started resorting to 'extreme' weight-loss diets to achieve a rapid reduction in weight. These extreme diets are either very low in carbohydrate or very low in fat. Such extreme diets not only make the diet unbalanced but also have safety issues. Moreover, these are not sustainable in the long run. The weight that is lost is regained within a short period of time when people go off these extreme diets. This explains why the popularity of most extreme diets peaks as well as wanes rapidly. Instead of resorting to such extreme diets, correction of obesity is best achieved with balanced, healthy, nutritious diets which are low in calories, combined with adequate physical activity (exercise). Motivational counselling can also help people to initiate weight loss and sustain this weight loss over longer periods of time.

Diet-related DNA adduct formation in relation to carcinogenesis

The human diet contributes significantly to the initiation and promotion of carcinogenesis. It has become clear that the human diet contains several groups of natural foodborne chemicals that are at least in part responsible for the genotoxic, mutagenic, and carcinogenic potential of certain foodstuffs. Electrophilic chemicals are prone to attack nucleophilic sites in DNA, resulting in the formation of altered nucleobases, also known as DNA adducts. Since DNA adduct formation is believed to signal the onset of chemically induced carcinogenesis, the DNA adduct-inducing potential of certain foodstuffs has been investigated to gain more insight into diet-related pathways of carcinogenesis. Many studies have investigated diet-related DNA adduct formation. This review summarizes work on known or suspected dietary carcinogens and the role of DNA adduct formation in hypothesized carcinogenesis pathways.

Nutritional and unhealthy behaviors in women with and without breast cancer

Background:

Breast cancer is the most common malignancy in women. Global statistics indicate increasing rates of this cancer. Nutrition, diet, and healthy behaviors are among influential factors in prevalence of breast cancer, and possibly affect its incidence through inflammatory and immune system responses.

Objectives:

This study was designed to compare nutritional and unhealthy behaviors in women with and without breast cancer referred to Mahdieh Imaging Center in Hamadan in 2013.

Patients and Methods:

This cross-sectional study is conducted on 232 women with r and without breast cancer referred to Mahdieh Imaging Center of Hamadan, Iran) in 2013 using random sampling method. Data were collected using nutritional and unhealthy behaviors questionnaires, and analyzed with SPSS-17 software using descriptive statistics and Mann-Whitney, independent t, and chi-square tests.

Results:

The mean scores of feeding type in the patients with and without breast cancer was 56.14 and 66.25, respectively. Results obtained from data analysis showed that there was statistically significant difference between the two groups in terms of nutrition (P < 0.001), but no relationship was observed between breast cancer and unhealthy behaviors.

Conclusions:

Given the results, improving skills, training and awareness is necessary for women and emphasis on modified diet is recommended as a non-medical option for prevention of breast cancer.

A micro-extraction technique using a new digitally controlled syringe combined with UHPLC for assessment of urinary biomarkers of oxidatively damaged DNA

The formation of reactive oxygen species (ROS) within cells causes damage to biomolecules, including membrane lipids, DNA, proteins and sugars. An important type of oxidative damage is DNA base hydroxylation which leads to the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 5-hydroxymethyluracil (5-HMUra). Measurement of these biomarkers in urine is challenging, due to the low levels of the analytes and the matrix complexity. In order to simultaneously quantify 8-oxodG and 5-HMUra in human urine, a new, reliable and powerful strategy was optimised and validated. It is based on a semi-automatic microextraction by packed sorbent (MEPS) technique, using a new digitally controlled syringe (eVol(®)), to enhance the extraction efficiency of the target metabolites, followed by a fast and sensitive ultrahigh pressure liquid chromatography (UHPLC). The optimal methodological conditions involve loading of 250 µL urine sample (1:10 dilution) through a C8 sorbent in a MEPS syringe placed in the semi-automatic eVol(®) syringe followed by elution using 90 µL of 20% methanol in 0.01% formic acid solution. The obtained extract is directly analysed in the UHPLC system using a binary mobile phase composed of aqueous 0.1% formic acid and methanol in the isocratic elution mode (3.5 min total analysis time). The method was validated in terms of selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), extraction yield, accuracy, precision and matrix effect. Satisfactory results were obtained in terms of linearity (r(2) > 0.991) within the established concentration range. The LOD varied from 0.00005 to 0.04 µg mL(-1) and the LOQ from 0.00023 to 0.13 µg mL(-1). The extraction yields were between 80.1 and 82.2 %, while inter-day precision (n = 3 days) varied between 4.9 and 7.7 % and intra-day precision between 1.0 and 8.3 %. This approach presents as main advantages the ability to easily collect and store urine samples for further processing and the high sensitivity, reproducibility, and robustness of eVol(®)MEPS combined with UHPLC analysis, thus retrieving a fast and reliable assessment of oxidatively damaged DNA.

Antioxidants: benefits and risks for long-term health

The oxidative modification hypothesis postulates that oxidative stress is one of the major factors in aging and the development of age-related disorders, including cardiovascular diseases. In this scenario, the oxidative modification of lipids, proteins and nucleic acids in vascular walls contributes to the etiology of cardiovascular disease, implying that consumption or therapeutic use of antioxidants could prevent the onset of such pathological disorders. Because of this, a number of studies have been conducted to address the question of whether cardiovascular diseases can be modulated by antioxidant treatment or consumption. Although some of the earliest data, collected in animal studies and epidemiologic studies have shown a measure of success, numerous clinical trials indicate that this approach is of minimal or no benefit. These conclusions represent a challenge to design more sensitive antioxidant trials in order to confirm or alter these conclusions. The focus of this review is on the benefits and disadvantages associated with the use of antioxidants, such as vitamins C and E, polyphenols, or antioxidant therapies, including hormone replacement therapy and iron reduction therapy, on overall vascular health.

Impact of oxidative stress on female fertility

PURPOSE OF REVIEW

To review the role of oxidative stress in the context of female fertility.

RECENT FINDINGS

Oxidative stress is associated with decreased female fertility in animal and in-vitro models, but no studies to date have directly assessed the relationship in women. Exposures associated with oxidative stress and with evidence to influence the timing and maintenance of a viable pregnancy include pregnancy complications (e.g. preeclampsia), extremes of body weight, alcohol, tobacco, and caffeine intake. Intake of antioxidant nutrients, including use of multivitamins, impacts the generation of reactive oxygen species and may play a beneficial role in female fertility.

SUMMARY

Infertility is a significant public health problem and diagnosis and treatment are stressful, invasive, and costly. The role of oxidative stress in female fertility is an understudied and compelling area for investigation. Identifying modifiable factors to decrease oxidative stress in the gynecologic environment may be an inexpensive and noninvasive therapy for increasing fertility.

Short-term moderate exercise programs reduce oxidative DNA damage as determined by high-performance liquid chromatography-electrospray ionization-mass spectrometry in patients with colorectal carcinoma following primary treatment

OBJECTIVE

Oxidative DNA damage is believed to be involved in tumor formation and may be an important biomarker for malignant transition or relapse. A decrease of such damage has been observed in human and animal studies following dietary intervention and/or changes in lifestyle such as physical exercise at different levels of intensity. The purpose of this study was to carry out a clinical trial comparing the effects of a short-term (2 weeks) exercise program of moderate intensity (0.3-0.4 x maximal exercise capacity) (MI) versus high intensity (0.5-0.6 x maximal exercise capacity) (HI) on individual urinary excretion of 8-oxo-dG before and after completion of the exercise programs.

MATERIAL AND METHODS

In this short-term, prospective and randomized trial, 19 patients with colorectal cancer were allocated to the MI group following primary therapy and 29 to the HI group. Urinary 8-oxo-dG excretion concentration was determined by a highly sensitive detection method using high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS). Concentrations were determined immediately before and after completion of the exercise programs.

RESULTS

Using HPLC-ESI-MS, it was shown that MI exercise significantly reduced urinary 8-oxo-dG excretion levels from 8.47 +/- 1.99 to 5.81 +/- 1.45 (ng/mg creatinine, mean +/- SE, p = 0.02), whereas HI exercise resulted in a non-significant increase from 5.00 +/- 1.31 to 7.11 +/- 1.63 (ng/mg creatinine, p = 0.18). Clinical characteristics (gender, age, body mass index (BMI), diet, chemotherapy/irradiation) were not associated/correlated with urinary 8-oxo-dG levels.

CONCLUSIONS

By using HPLC-ESI-MS it was shown that short-term MI exercise after primary therapy in patients with colorectal cancer was associated with lower levels of urinary 8-oxo-dG, suggesting decreased oxidative DNA damage. In contrast, HI exercise tended to increase DNA damage. A prospective trial is now warranted to prove that reduced oxidative DNA damage lowers the risk of relapse of colorectal cancer in treated patients.

Green tea extract only affects markers of oxidative status postprandially: lasting antioxidant effect of flavonoid-free diet

Epidemiological studies suggest that foods rich in flavonoids might reduce the risk of cardiovascular disease and cancer. The objective of the present study was to investigate the effect of green tea extract (GTE) used as a food antioxidant on markers of oxidative status after dietary depletion of flavonoids and catechins. The study was designed as a 2×3 weeks blinded human cross-over intervention study (eight smokers, eight non-smokers) with GTE corresponding to a daily intake of 18·6 mg catechins/d. The GTE was incorporated into meat patties and consumed with a strictly controlled diet otherwise low in flavonoids. GTE intervention increased plasma antioxidant capacity from 1·35 to 1·56 (P<0·02) in postprandially collected plasma, most prominently in smokers. The intervention did not significantly affect markers in fasting blood samples, including plasma or haemoglobin protein oxidation, plasma oxidation lagtime, or activities of the erythrocyte superoxide dismutase, glutathione peroxidase, glutathione reductase and catalase. Neither were fasting plasma triacylglycerol, cholesterol, α-tocopherol, retinol, β-carotene, or ascorbic acid affected by intervention. Urinary 8-oxo-deoxyguanosine excretion was also unaffected. Catechins from the extract were excreted into urine with a half-life of less than 2 h in accordance with the short-term effects on plasma antioxidant capacity. Since no long-term effects of GTE were observed, the study essentially served as a fruit and vegetables depletion study. The overall effect of the 10-week period without dietary fruits and vegetables was a decrease in oxidative damage to DNA, blood proteins, and plasma lipids, concomitantly with marked changes in antioxidative defence.

A review of the effects and mechanisms of polyphenolics in cancer

This paper is a comprehensive review of the effects of bioactive polyphenolic compounds commonly found in many fruits and vegetables on cancer. These include the pheniolic acids, anthocyanins, catechins, stilbenes and several other flavonoids. We have attempted to compile information from most of the major studies in this area into one source. The review encompasses the occurrence and bioavailability of the polyphenolics, the in vitro and in vivo evidence for their effects on cancer, both positive and negative, and the various mechanisms by which the chemicals may exert their effects. Although most of the work done to date indicates a chemopreventative activity of these compounds, there are some studies that show cancer-inducing or no effects. There are several common mechanisms by which these chemicals exert their effects that could be conducive to additive, synergistic, or antagonistic interactions. These include effects on cellular differentiation, proliferation, and apoptosis, effects on proteins and enzymes that are involved in these processes at a molecular level, and other various effects through altered immune function and chemical metabolism.

Diet and biomarkers of oxidative damage in women previously treated for breast cancer

This study sought to evaluate the relationship between dietary intake of fat, polyunsaturated fat, saturated fat, arachidonic acid, and selected dietary antioxidants and levels of oxidative damage as measured by urinary levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-epi-prostaglandin F2alpha (8-iso-PGF2alpha) in women previously treated for breast cancer. Two hundred two study subjects participating in the Women's Healthy Eating and Living (WHEL) study were included in this ancillary study. Dietary intakes and concentrations of urinary 8-OHdG and 8-iso-PGF2alpha were measured at baseline and 12 mo in the 179 women included in the analytical cohort. Study subjects demonstrated a significant reduction in dietary total, polyunsaturated, and saturated fat intake and a significant increase in vitamins E and C and beta-carotene intake from baseline to 12 mo. Linear mixed-models analysis using baseline and Year 1 data indicated that vitamin E intake was inversely associated with both 8-OHdG and 8-iso-PGF2alpha. 8-Iso-PGF2alpha is increased with increased body mass index (BMI) and polyunsaturated fatty acid (PUFA) intake, indicating an increase in lipid peroxidation with greater BMI and higher PUFA intake. 8-OHdG was inversely related to age but positively related to arachidonic acid, indicating an increase in DNA damage with higher intake of arachidonic acid (meat). The results of this nested case-controlled study provide potential mechanisms by which a high fruit and vegetable, low-fat diet might reduce the recurrence rate of or early-stage breast cancer.

Effect of a Soymilk Supplement Containing Isoflavones on Urinary F2 Isoprostane Levels in Premenopausal Women

Epidemiological studies have associated soy diets with reduced risk of breast and some other cancers, and oxidative cellular damage may contribute to the development of these and other diseases. We tested the effect of a soymilk supplement rich in isoflavones on a measure of cellular lipid peroxidation in a controlled feeding study. Eight premenopausal women consumed a constant diet that included soymilk containing 113-207 mg/day total isoflavones and 4 mo later a constant soy diet low (<5 mg/day) in isoflavones, both for a complete menstrual cycle. The average daily urinary excretions of daidzein and genistein were 24.6 +/- 10.1 and 9.2 +/- 6.1 mg/day, respectively, during the high-isoflavone soy diet and were below the detection limit during the low-isoflavone diet. F2 isoprostane 8-iso-PGF-2alpha excretion varied widely within and between subjects, and the group mean was not significantly different during the high- and low-isoflavone soy diet (7.67 +/- 1.13 and 8.65 +/- 1.18 nmol/12 h, mean +/- SD, respectively). However, individual changes in 8-iso-PGF-2alpha between the two soymilk drinks were significantly associated with age (r = -0.87; P = 0.006) and several measures of isoflavone exposure, namely, daidzein dose (r = 0.81; P = 0.015), combined daidzein and genistein dose (r = 0.77; P = 0.03), and total urinary excretion of isoflavones (daidzein, genistein, and equol) (r = 0.71; P = 0.05). The findings suggest that soy isoflavones may reduce lipid peroxidation in an age-dependent manner, with greater effects in older women, and with lower doses of isoflavones.

Breast cancer in sub-Saharan Africa: how does it relate to breast cancer in African-American women?

BACKGROUND

African-American women have had a lower incidence, yet higher mortality rate from breast cancer compared with White-American women. African-American women also have had a higher risk for early-onset, high-grade, node-positive, and hormone receptor-negative disease. Similar features have characterized hereditary breast cancer, prompting speculation that risk factors could be genetically transmitted. Further evaluation of this theory required the study of breast cancer among women from sub-Saharan Africa because of their shared ancestry with African-American women.

METHODS

Publications from 1988 to 2004 of English-language literature on breast cancer in Africa were reviewed.

RESULTS

Women from sub-Saharan Africa were found to have a low incidence of breast cancer. This was partly explained by a largely protective reproductive history, including late menarche, early menopause, high parity with prolonged breastfeeding, irregular menses, and fewer ovulatory cycles. The average age at diagnosis, however, was approximately 10 years younger than breast cancer patients of western nations, and disease stage distribution was shifted toward more advanced disease, which resulted in higher mortality rates. These features were found to be similar to data on breast cancer in African-American women. Mutations in BRCA1 and BRCA2 have been reported in African-American women, but the extent of the contribution of BRCA1 and BRCA2 to breast cancer burden in Africa was uncertain. Limited financial resources lead to suboptimal cancer data collection, as well as delayed diagnosis and treatment of many African breast cancer patients.

CONCLUSIONS

Parallels between breast cancer burdens of African-American and sub-Saharan-African women were provocative, indicating the need for further exploration of possible genetically transmitted features related to estrogen metabolism and/or breast cancer risk.

Dried Fruits: Excellentin Vitroandin VivoAntioxidants

OBJECTIVE

The goal of this work is to determine the amount and quality of phenol antioxidants in dried fruits and compare them with the corresponding fresh fruits; to compare the nutrients in fresh and dried fruits; to determine if figs are a source of in vivo antioxidants when eaten.

METHODS

Commercial samples of dried fruits and fresh fruits were compared in the in vitro studies using a colorimetric method to measure phenolic antioxidants. The quality of the antioxidants was measured by inhibition of lower density lipoprotein oxidation. Ten normal free-living subjects were tested in the human study. Fasting subjects were given 40 g of figs with or without a carbonated beverage and the plasma antioxidant capacity was measured for six hours using the trolox equivalent antioxidant capacity assay.

RESULTS

Dates have the highest concentration of polyphenols among the dried fruits. Figs and dried plums have the best nutrient score among the dried fruits, and dates among the fresh fruits. Processing to produce the dried fruit significantly decreases the phenols in the fruits on a dry weight basis. Compared with vitamins C and E, dried fruits have superior quality antioxidants with figs and dried plums being the best. Fig antioxidants can enrich lipoproteins in plasma and protect them from subsequent oxidation. Figs produced a significant increase in plasma antioxidant capacity for 4 hours after consumption, and overcome the oxidative stress of consuming high fructose corn syrup in a carbonated soft drink.

CONCLUSION

Dried fruits and especially figs, are a convenient and superior source of some nutrients, but in the American diet amount to less than 1% of total fruit consumed. Figs are in vivo antioxidants after human consumption. The findings suggest that dried fruits should be a greater part of the diet as they are dense in phenol antioxidants and nutrients, most notably fiber.

Peroxyl radical mediated oxidative DNA base damage: implications for lipid peroxidation induced mutagenesis

Endogenous DNA damage induced by lipid peroxidation is believed to play a critical role in carcinogenesis. Lipid peroxidation generates free radical intermediates (primarily peroxyl radicals, ROO(*)) and electrophilic aldehydes as the principal genotoxicants. Although detailed information is available on the role of aldehyde base adducts in mutagenesis and carcinogenesis, the contribution of peroxyl radical mediated DNA base damage is less well understood. In the present study we have mapped oxidative base damage induced by peroxyl radicals in the supF tRNA gene and correlated this information with peroxidation-induced mutations in several human fibroblast cell lines. Nearly identical patterns of oxidative base damage were obtained from reaction of DNA with either peroxidizing arachidonic acid (20:4omega6) or peroxyl radicals generated by thermolysis of ABIP in the presence of oxygen. Oxidative base damage primarily occurred at G and C. Transversions at GC base pairs in the supF gene were the major base substitution detected in all cell lines. Peroxyl radical induced tandem mutations were also observed. Many mutation hot spots coincided with sites of mapped oxidative lesions, although in some cases hot spots occurred adjacent to the damaged base. Evidence is presented for the involvement of 8-oxodG in the oxidation of DNA by ROO(*). These results are used to interpret some key features of previously published mutation spectra induced by lipid peroxidation in human cells.

Varietal differences in phenolic content and antioxidant and antiproliferative activities of onions

Epidemiological studies have indicated that the consumption of fruits and vegetables is associated with a reduced risk for the development of chronic diseases, such as cardiovascular disease and cancer. Phytochemicals, including phenolics and flavonoids, are suggested to be the major bioactive compounds contributing to the health benefits of fruits and vegetables. Onions are a major source of dietary flavonoids; however, there may exist varietal differences in composition, concentration, and beneficial activities. To characterize these differences, shallots and 10 onion (Allium cepa L.) varieties commonly available in the United States (Western Yellow, Northern Red, New York Bold, Western White, Peruvian Sweet, Empire Sweet, Mexico, Texas 1015, Imperial Valley Sweet, and Vidalia) were evaluated for total phenolic and flavonoid contents and antioxidant and antiproliferative activities. Shallots contained the highest total phenolic content (114.7 +/- 10.0 mg/100 g of sample) among the varieties tested, with a 6-fold difference observed when compared to the variety with the lowest phenolic content (Vidalia, p < 0.05). Western Yellow onion variety exhibited the highest total flavonoid content (69.2 +/- 3.7 mg/100 g of onion) of the varieties tested, with an 11-fold difference when compared to the variety with the lowest flavonoid content (Western White, p < 0.05). Shallots exhibited the highest total antioxidant activity (45.5 +/- 2.1 micromol of vitamin C equiv/g of onion), followed by Western Yellow, New York Bold, Northern Red, Mexico, Empire Sweet, Western White, Peruvian Sweet, Texas 1015, Imperial Valley Sweet, and Vidalia. For all varieties, both total phenolic and flavonoid contents were strongly correlated with total antioxidant activity (R (2) = 0.9668, p < 0.05; and R (2) = 0.7033, p < 0.05, respectively). The proliferation of HepG(2) and Caco-2 cells was significantly inhibited in a dose-dependent fashion after exposure to the Western Yellow, shallots, New York Bold, and Northern Red extracts, with Western Yellow, shallots, and New York Bold exhibiting the highest antiproliferative activity against HepG(2) cells and New York Bold and Western Yellow exhibiting the highest antiproliferative activity against Caco-2 cells. However, the varieties of Western White, Peruvian Sweet, Empire Sweet, Mexico, Texas 1015, Imperial Valley Sweet, and Vidalia demonstrated weak antiproliferative activity against both HepG(2) and Caco-2 cells. These results may influence consumers toward purchasing onion varieties exhibiting greater potential health benefits and may significantly affect future breeding efforts to enhance onion nutritional qualities.

Myeloperoxidase Genotype, Fruit and Vegetable Consumption, and Breast Cancer Risk

Myeloperoxidase (MPO), an antimicrobial enzyme in the breast, generates reactive oxygen species (ROS) endogenously. An MPO G463A polymorphism exists in the promoter region, with the variant A allele conferring lower transcription activity than the common G allele. Because oxidative stress may play a role in breast carcinogenesis, we evaluated MPO genotypes in relation to breast cancer risk among 1,011 cases and 1,067 controls from the Long Island Breast Cancer Study Project (1996-1997). We also assessed the potential modifying effects of dietary antioxidants and hormonally related risk factors on these relationships. Women over 20 years with incident breast cancer who were residents of Nassau and Suffolk Counties, NY, were identified as potential cases. Population-based controls were frequency matched by 5-year age groups. Genotyping was performed with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) technology, and suspected breast cancer risk factors and usual dietary intake were assessed during an in-person interview. Unconditional logistic regression was used to estimate odds ratios and 95% confidence intervals. Having at least one A allele was associated with an overall 13% reduction in breast cancer risk. When consumption of fruits and vegetables and specific dietary antioxidants were dichotomized at the median, inverse associations with either GA or AA genotypes were most pronounced among women who consumed higher amounts of total fruits and vegetables (odds ratio, 0.75; 95% confidence interval, 0.58-0.97); this association was not noted among the low-consumption group (P for interaction = 0.04). Relationships were strongest among premenopausal women. Results from this first study of MPO genotypes and breast cancer risk indicate that MPO variants, related to reduced generation of ROS, are associated with decreased breast cancer risk, and emphasize the importance of fruit and vegetable consumption in reduction of breast cancer risk.

Moderate alcohol consumption and levels of antioxidant vitamins and isoprostanes in postmenopausal women

BACKGROUND

Although alcohol intake has been positively associated with breast cancer risk in epidemiologic studies, the mechanisms mediating this association are speculative.

OBJECTIVE

The Postmenopausal Women's Alcohol Study was designed to explore the effects of moderate alcohol consumption on potential risk factors for breast cancer. In the present analysis, we evaluated the relationship of alcohol consumption with antioxidant nutrients and a biomarker of oxidative stress.

DESIGN

Participants (n=53) consumed a controlled diet plus each of three treatments (15 or 30 g alcohol/day or a no-alcohol placebo beverage), during three 8-week periods in random order. We measured the antioxidants, vitamin E (alpha (alpha)- and gamma (gamma)-tocopherols), selenium, and vitamin C in fasting blood samples which were collected at the end of diet periods, treated and frozen for assay at the end of the study. We also measured 15-F(2t)-IsoP isoprostane, produced by lipid peroxidation, which serves as an indicator of oxidative stress and may serve as a biomarker for conditions favorable to carcinogenesis.

RESULTS

After adjusting for BMI (all models) and total serum cholesterol (tocopherol and isoprostane models) we observed a significant 4.6% decrease (P=0.02) in alpha-tocopherol and a marginally significant 4.9% increase (P=0.07) in isoprostane levels when women consumed 30 g alcohol/day (P=0.06 and 0.05 for overall effect of alcohol on alpha-tocopherol and isoprostanes, respectively). The other antioxidants were not significantly modified by the alcohol treatment.

CONCLUSIONS

These results suggest that moderate alcohol consumption increases some biomarkers of oxidative stress in postmenopausal women.

Antioxidant and antiproliferative activities of strawberries

Strawberries contain high levels of antioxidants, which have been correlated with a decreased risk of chronic disease. To more fully characterize the antioxidant profiles and possible associated health benefits of this fruit, the total free and bound phenolic, total flavonoid, and total anthocyanin contents of eight strawberry cultivars (Earliglow, Annapolis, Evangeline, Allstar, Sable, Sparkle, Jewel, and Mesabi) were measured. Cultivar effects on phenolic contents were compared with antioxidant capacities, as measured by the total oxyradical scavenging capacity (TOSC) assay, and to antiproliferative activities, as measured by inhibition of HepG(2) human liver cancer cell proliferation in vitro. Free phenolic contents differed by 65% between the highest (Earliglow) and the lowest (Allstar) ranked cultivars. The water soluble bound and ethyl acetate soluble bound phenolic contents averaged 5% of the total phenolic content of the cultivars. The total flavonoid content of Annapolis was 2-fold higher than that of Allstar, which had the lowest content. The anthocyanin content of the highest ranked cultivar, Evangeline, was more than double that of the lowest ranked cultivar, Allstar. Overall, free phenolic content was weakly correlated with total antioxidant activity, and flavonoid and anthocyanin content did not correlate with total antioxidant activity. The proliferation of HepG(2) human liver cancer cells was significantly inhibited in a dose-dependent manner after exposure to all strawberry cultivar extracts, with Earliglow exhibiting the highest antiproliferative activity and Annapolis exhibiting the lowest. No relationship was found between antiproliferative activity and antioxidant content.

Serum and plasma concentration of oxidant and antioxidants in patients of Helicobacter pylori gastritis and its correlation with gastric cancer

Serum superoxide dismutase, plasma ascorbic acid and lipid peroxidation in H. pylori gastritis and gastric cancer patients were compared with values for age matched healthy subjects. Serum superoxide dismutase and serum malondialdehyde were analyzed spectrophotometrically whereas plasma ascorbic acid was determined by colorimetric method. Significant increase in serum superoxide dismutase and serum malondialdehyde and significant decrease in plasma ascorbic acid were observed in H. pylori gastritis and gastric cancer patients compared to control subjects. The concentration of serum superoxide dismutase and serum malondialdehyde was significantly higher and plasma ascorbic acid was significantly lower in gastric cancer as compared to H. pylori gastritis patients. Our results demonstrate that a correlation existed between the concentration of serum superoxide dismutase, plasma ascorbic acid and lipid peroxidation in H. pylori gastritis and gastric cancer patients.

Oxidative stress, DNA damage, and breast cancer

Oxidative stress is a disturbance in the balance between the production of reactive oxygen species (ROS) and antioxidant defenses. It occurs when excessive production of ROS overwhelms the antioxidant defense system or when there is a significant decrease or lack of antioxidant defenses. Oxidative stress, in turn, is known to cause DNA damage and mutations of tumor suppressor genes that are critical initial events in carcinogenesis. Interestingly, early findings of the studies suggest that environmental factors, such as high psychological stress and poor nutritional profile (eg, low antioxidant and high fat intake), increase ROS production. Given that breast cancer is a complex disorder in which gene-environment interactions play a significant role in the development of cancer, oxidative stress may be an excellent model for exploring mechanisms mediating gene-environment interactions for nurse scientists and advanced practice nurses. Such investigations may help to suggest future strategies for nonpharmacological interventions for decreasing cancer risk.

Associations between dietary antioxidant intake and oxidative stress in HIV-seropositive and HIV-seronegative men and women

OBJECTIVE

To describe the relationship between dietary antioxidant intake and oxidative stress in clinically stable HIV-positive and HIV-negative adults.

DESIGN

A cross-sectional study.

METHODS

Average total daily dietary intakes of vitamin C, beta-carotene, alpha-tocopherol, selenium, and zinc from foods and nutritional supplements were estimated in noninstitutionalized individuals using the dietary history method. Plasma malondialdehyde (MDA) concentrations were measured by high-performance-liquid-chromatography (HPLC) whereas peripheral blood mononuclear cell glutathione (PBMC GSH) concentrations were determined spectrophotometrically by an enzymatic recycling assay. Data were analyzed in multiple linear regression models to investigate these relationships.

RESULTS

Regression analysis revealed an inverse relationship between selenium intake and plasma MDA in a model that included the five dietary antioxidants ( R 2 = 0.25; p < .02) and with selenium only ( R 2 = 0.19; p < .01). Both models were adjusted for gender, smoking status, and HIV seropositivity. Antioxidant intake was not associated with PBMC GSH ( R 2 = 0.12, p = .36). In univariate analyses, oxidative stress did not significantly differ between clinically stable HIV-positive and healthy HIV-negative study subjects.

CONCLUSIONS

This is the first study to characterize the relationship between dietary antioxidant intake from food and supplements with oxidative stress. The results suggested dietary selenium intake was strongly and inversely associated with plasma MDA, but dietary antioxidant intakes were not related to PBMC GSH. This study also provides evidence that HIV infection was not specifically associated with oxidative stress among clinically stable individuals.

Phenol antioxidant quantity and quality in foods: fruits

The free and bound phenols have been measured in 20 fruits commonly consumed in the American diet. Phenols were measured colorimetrically using the Folin-Ciocalteu reagent with catechin as the standard after correction for ascorbic acid contribution. On a fresh weight basis, cranberry had the highest total phenols, and was distantly followed by red grape. Free and total phenol quality in the fruits was analyzed by using the inhibition of lower density lipoprotein oxidation promoted by cupric ion. Ascorbate had only a minor contribution to the antioxidants in fruits with the exception of melon, nectarine, orange, white grape, and strawberry. The fruit extracts' antioxidant quality was better than the vitamin antioxidants and most pure phenols, suggesting synergism among the antioxidants in the mixture. Using our assay, fruits had significantly better quantity and quality of phenol antioxidants than vegetables. Fruits, specifically apples and cranberries, have phenol antioxidants that can enrich lower density lipoproteins and protect them from oxidation. The average per capita consumption of fruit phenols in the U.S. is estimated to be 255 mg/day of catechin equivalents.

Increased formation of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine, in human breast cancer tissue and its relationship to GSTP1 and COMT genotypes

Reactive oxygen species (ROS) induced damage to DNA plays a major role in carcinogenesis. In order to estimate the level of oxidative damage and its role in breast cancer, 8-hydroxy-2'-deoxyguanosine (8-OHdG) was determined in DNA isolated from human breast tissue. Furthermore, we investigated whether polymorphisms in genes for enzymes involved in generation and elimination of ROS had any association with the level of 8-OHdG in breast tissue. In this study, the level of 8-OHdG in DNA was measured by the high performance liquid chromatography-electrochemical detector (HPLC-ECD) method. Genotypes of cytochrome P450 (CYP)1A1, glutathione S-transferase (GST)M 1, GSTP1 and catechol O-methyltransferase (COMT) were determined by PCR-based restriction fragment length polymorphism analysis. A total of 61 Japanese patients were included in the study. The mean level of 8-OHdG in DNA of breast cancer tissues was 2.07 +/- 0.95 per 10(5) dG residues, while the mean level of 8-OHdG in DNA of non-cancerous breast tissues was 1.34 +/- 0.46 per 10(5) dG residues. The 8-OHdG levels in DNA of breast cancer tissues were significantly higher than those of their corresponding non-cancerous breast tissues (P < 0.0001). There was negative correlation between the clinical stage and the mean level of 8-OHdG in DNA of breast cancer tissues. Furthermore, patients with genotype of high GSTP1 activity had lower level of 8-OHdG in DNA of breast cancer tissues than others. On the contrary, the mean level of 8-OHdG in DNA of breast cancer tissues was higher among patients with genotype of high COMT activity. Our findings support the assumption that cancer cells are more exposed to oxidative stress than adjacent non-cancerous tissue. Genetic polymorphisms in enzymes involved in ROS metabolism may have a role in individual susceptibility to oxidant-related breast disease. At the same time, reduction of oxidative stress is thought to be a very important measure for primary prevention of breast cancer.

Oxidants and antioxidants in breast cancer

Although a number of risk factors have been identified for breast cancer, mechanisms by which they increase risk of the disease are not clear. Breast cancer etiology could, in part, be related to oxidative stress. Recognized risk factors for breast cancer include a family history of the disease. BRCA1 is needed for post-transcriptional repair of oxidative damage, indicating that oxidative stress may be an important risk factor for women with a family history of the disease. Reproductive and hormonal factors that result in greater exposure to circulating estrogens also increase risk, and steroid hormones are metabolized to reactive quinones and hydroquinones, which can directly damage DNA. Alcohol consumption is associated with increased risk, and the metabolism of alcohol results in production of DNA-damaging reactive oxygen species (ROS). Finally, the inverse relationship noted with consumption of fruits and vegetables could be related to their being a source of antioxidant vitamins. Endogenous factors may play an equally important role in the effects of oxidative stress on breast carcinogenesis. Genetic variability in enzymes that result in increased production of ROS and those that protect the cell from oxidative stress could also have an impact for risk of the disease. In this review, a rationale is given for linking breast cancer risk factors to oxidative stress. The possible role of genetic polymorphisms in a number of enzymes that may be important in affecting levels of ROS to which the cell is exposed, as well as those that protect the cell from oxidative stress, is discussed.

Effect of increased vegetable and fruit consumption on markers of oxidative cellular damage

The goal of this study was to test the hypothesis that increased consumption of vegetables and fruit would reduce markers of oxidative cellular damage that can be assessed in blood or urine. Twenty-eight women participated in a 14 day dietary intervention. The primary end-points assessed were: 8-hydroxydeoxyguanosine (8-OHdG) in DNA isolated from peripheral lymphocytes, determined by HPLC with electrochemical detection; 8-OHdG excreted in urine, measured by ELISA; malondialdehyde (MDA) in urine, measured by fluorimetric detection following derivatization with thiobarituric acid and separation via HPLC; urinary 8-isoprostane F-2alpha (8-EPG) detected by ELISA. Pre- and post-intervention plasma levels of selected carotenoids were determined by HPLC. Subjects were free living and consumed a completely defined recipe-based diet that increased their average daily consumption of vegetables and fruit from 5.8 servings at baseline to 12.0 servings throughout the intervention. Overall, the level of 8-OHdG in DNA isolated from lymphocytes and in urine and the level of 8-EPG in urine were reduced by the intervention, whereas urine concentrations of MDA were minimally affected. The reduction in lymphocyte 8-OHdG was greater in magnitude (32 versus 5%) in individuals with lower average pre-intervention levels of plasma alpha-carotene (56 ng/ml) than in individuals with higher average pre-intervention plasma levels of alpha-carotene (148 ng/ml). The results of this study indicate that consumption of a diet that significantly increased vegetable and fruit intake from a diverse number of botanical families resulted in significant reductions in markers of oxidative cellular damage to DNA and lipids.