Primary Versus Secondary Prevention Effects of a Gender-Transformative Sexual Violence Prevention Program Among Male Youth: A Planned Secondary Analysis of a Randomized Clinical Trial

Engaging adolescent males is a promising violence prevention strategy. This study explored primary versus secondary prevention effects of a gender-transformative program (i.e., Manhood 2.0) versus job-readiness training on multiple forms of violence perpetration. Adolescent males, ages 13 to 19 years, were recruited through youth-serving organizations in Pittsburgh, PA, between July 27, 2015, and June 5, 2017, to participate in an unblinded community-based cluster-randomized trial in 20 neighborhoods. The intervention curriculum, Manhood 2.0, focused on challenging norms that foster gender-based violence and building bystander skills. The control program was job-readiness training. We completed a planned secondary analysis of surveys from baseline and 9 months post intervention (follow-up), wherein we stratified participants based on any sexual violence/adolescent relationship abuse (SV/ARA) at baseline and examined risk of perpetration of SV/ARA, incapacitated sex, sexual harassment, cyber sexual abuse, peer violence, bullying, and homophobic teasing at follow-up. Among 866 participants, mean age was 15.6 years, 70% identified as Black, 6% as Hispanic, and 6% as multiracial. In both the Manhood 2.0 intervention group and job-readiness control groups, youth who reported SV/ARA at baseline were significantly more likely to report any form of SV/ARA, incapacitated sex, sexual harassment, cyber sexual abuse, bullying, and homophobic teasing at follow-up. Among participants who reported no SV/ARA perpetration at baseline, participating in the Manhood 2.0 intervention program was associated with increased risk of SV/ARA at follow-up compared to participating in the job-readiness control program. Among participants who reported SV/ARA perpetration at baseline, participating in the Manhood 2.0 intervention group was associated with lower risk of peer violence at follow-up. Synergizing gender-transformative approaches with job-readiness training may offer opportunities for crosscutting prevention programming to address multiple forms of violence.

School Absenteeism Among Middle School Students With High Exposure to Violence

OBJECTIVE

Chronic school absenteeism is linked to failure to graduate high school and poor health in adulthood. Contextual factors associated with absenteeism may be under-recognized in school and clinical settings. We examined the prevalence of self-reported absenteeism and violence exposure and their association among middle school students with identified risk of trauma.

METHODS

We analyzed baseline data from a dating violence prevention program. Participants completed surveys identifying lifetime exposure to 10 types of violence and past 30-day absence. Violence exposure and absenteeism were summarized and compared across demographic groups. Generalized linear models examined associations between 1) any history of violence exposure, 2) each type of violence exposure, and 3) summed exposures to different types of violence, and frequent absenteeism (≥2 absences in past 30 days).

RESULTS

Of all participants (overall n = 499), 45.5% reported frequent absenteeism and 71.5% reported violence exposure. Any self-reported violence exposure was associated with absenteeism (aRR = 1.43, 95%CI: 1.06-1.92). However, no specific type of violence exposure predicted absenteeism. Comparing summed exposures to different types of violence to no violence exposure, exposure to 1 type of violence was associated with absenteeism (aRR = 1.59, 95%CI: 1.15-2.20), with no evidence of stronger associations with greater exposure (2-3 types: aRR = 1.37, 95%CI: 1.00-1.88; ≥4 types: aRR = 1.31, 95%CI: 0.98-1.74).

CONCLUSIONS

Youth in this sample reported both high rates of violence exposure and absenteeism. Prior violence exposure was associated with absenteeism. Resources and contextual support for youth exposed to family or community violence may play a role in school attendance, emphasizing need for trauma-sensitive approaches to absenteeism.

Wellness and resilience for college and beyond: protocol for a quasi-experimental pilot study investigating a dialectical behaviour therapy skill-infused college course

INTRODUCTION

College students' mental health problems and suicidal behaviour are serious, persistent and prevalent public health issues. With the need for mental health support greatly exceeding the availability of on-campus treatment, a recent trend on college campuses is to offer courses designed to teach students strategies for developing mental health or resilience. While these courses are exceptionally popular among students, a paucity of research investigates the health outcomes associated with participation. The purpose of this study is to investigate the acceptability, appropriateness, feasibility and preliminary effectiveness of a college course grounded in skills from dialectical behaviour therapy (DBT) titled, 'Wellness and Resilience for College and Beyond'.

METHODS AND ANALYSIS

During the spring and fall 2020 semesters, the course will be offered on five campuses in Southwestern Pennsylvania and West Virginia. The course consists of 15 weekly 2.5-hour lessons, weekly homework assignments and a final examination with content drawn from DBT, acceptance and commitment therapy and positive psychology. Undergraduate students aged 18-24 will self-select into the course and control subjects receiving 'university as usual' will be recruited to serve as a comparison group. Students who receive the course will complete measures of course acceptability, appropriateness and feasibility. All study participants will complete measures of adaptive coping skills use, emotion dysregulation and suicidality.

ETHICS AND DISSEMINATION

All of the study procedures were approved as an exempt protocol for evaluation of educational curricula by the University of Pittsburgh Human Research Protections Office (HRPO); the study was approved as a research study by the institutional review board (IRB) of the fifth study site. The University of Pittsburgh HRPO served as the IRB of record for all except one study site, which required standard IRB review. Data from this study will be disseminated via conference presentations, peer-reviewed publications and via our online stakeholder learning collaborative.

TRIAL REGISTRATION NUMBER

NCT04338256.

SAT-LB005 Association of Serum Estrogens and Estrogen Metabolites with Use of Non-Steroidal Anti-Inflammatory Drugs in Postmenopausal Women

Background: In several recent studies of postmenopausal women, the use of non-steroidal anti-inflammatory drugs (NSAIDs) has been associated with lower circulating estrogens. These analgesics have also been studied in association with breast cancer risks with inconsistent findings. Cross-talk between immune and endocrine factors may play important roles in the development of breast cancer. Methods: We conducted a study of postmenopausal women drawn from the Prostate, Lung, Colon and Ovarian Cancer Screening Trial cohort (PLCO). At study baseline, participants reported their frequency of use for aspirin, non-aspirin NSAIDs via questionnaire. High-performance liquid chromatography-tandem mass spectrometry was used to measure estrogens and estrogen metabolites (EM) in baseline serum samples from 354 women who went on to get breast cancer during study follow-up, and 423 women who remained healthy. All selected participants reported no use of menopausal hormones at study baseline. General linear models were used to estimate multivariable-adjusted mean EM by self-reported use of analgesics (daily, weekly, or less than weekly) in all participants, while adjusting for continuous age, baseline BMI and breast cancer outcome. Results: In comparison to women who reported that they did not use any NSAIDs on a daily basis, those reporting daily use of aspirin only, daily use of non-aspirin NSAIDs only and daily use of both aspirin and non-aspirin NSAIDs had lower multivariable adjusted serum concentrations of unconjugated estradiol (Pdiff<0.02). Greater frequency of non-aspirin NSAID use was associated with trends towards lower concentrations of total EM (Ptrend=.004), estrone (Ptrend=.004), and unconjugated estradiol (Ptrend=.04), and higher ratios of 2- and 4- hydroxylated EM to the parent estrogens (Ptrend=.02 and .04). Associations were similar in women who did and did not go on to have breast cancer. Discussion: In this sample of postmenopausal women, more frequent use of NSAIDs was associated with lower circulating estrogens and with patterns of estrogen metabolism that may be more favorable with respect to breast cancer risk. These results require independent confirmation in additional well-designed studies. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

Reliability of Urinary 6-sulfatoxymelatonin as a Biomarker in Breast Cancer

The objective of this study is to evaluate the effect of cryopreservation at different storage temperatures on urinary 6-sulfatoxymelatonin (aMT6s) concentration. Overnight urine from 28 postmenopausal women participating in the ORDET cohort study was filtered and separated into 6 mL aliquots. Urine samples were stored at –80°C and at –30°C for an average of 14 years. Urinary aMT6s concentration was assessed using a competitive immunoassay. Mean aMT6s values of samples stored at –30°C were systematically lower than those of samples stored at –80°C (10.7 ng/mL versus 15.8 ng/mL, p<0.001). Bland Altman plots showed disagreement between determinations at different storage temperatures at the highest levels of the metabolite concentration. The degree of agreement evaluated in terms of intra-class correlation coefficient was 0.68 (95% CI 0.41–0.84, p<0.0001). Pearson's correlation coefficient between aMT6s values of the two differently stored samples was 0.93 (p<0.001), while the Kendal tau coefficient for rank distribution was 0.73 (p<0.001). Our data suggest that storage temperatures might affect degradation of aMT6s during storage. However, individual characterization by melatonin levels does not seem to be affected by cryopreservation conditions.

p53 status as effect modifier of the association between pre-treatment fasting glucose and breast cancer outcomes in non diabetic, HER2 positive patients treated with trastuzumab

Mounting evidence supports the role of p53 in metabolic processes involved in breast carcinogenesis. We investigated whether p53 status affects the association of pre-treatment fasting glucose with treatment outcomes in 106 non diabetic, HER2 positive breast cancer patients treated with trastuzumab. p53 status was validated against gene sequencing of selected codons in 49 patients. The Kaplan-Meier method and log rank test were used to compare survival by categories of fasting glucose in the overall population and separate settings. Cox models included age and body mass index. Direct sequencing confirmed the lack of mutations in 73.7% of p53 negative patients and their presence in 53.3% of p53 positive cases. At 66 months, 88.3% of patients with glucose ≤ 89.0 mg/dl (median value) did not experiment disease progression compared with 70.0% in the highest category (p=0.034), with glucose being an independent predictor (p=0.046). Stratified analysis confirmed this association in p53 negative patients only (p=0.01). In the early setting, data suggested longer disease free survival in p53 negative patients in the lowest glucose category (p=0.053). In our study, p53 status acted as effect modifier of the investigated association. This may help differentiate target sub-groups and affect outcomes interpretation in similarly characterized patients.

Relationship of serum estrogens and metabolites with area and volume mammographic densities

Elevated mammographic density is a breast cancer risk factor, which has a suggestive, but unproven, relationship with increased exposure to sex steroid hormones. We examined associations of serum estrogens and estrogen metabolites with area and novel volume mammographic density measures among 187 women, ages 40-65, undergoing diagnostic breast biopsies at an academic facility in Vermont. Serum parent estrogens, estrone and estradiol, and their 2-, 4-, and 16-hydroxylated metabolites were measured using liquid chromatography-tandem mass spectrometry. Area mammographic density was measured in the breast contralateral to the biopsy using thresholding software; volume mammographic density was quantified using a density phantom. Linear regression was used to estimate associations of estrogens with mammographic densities, adjusted for age and body mass index, and stratified by menopausal status and menstrual cycle phase. Weak, positive associations between estrogens, estrogen metabolites, and mammographic density were observed, primarily among postmenopausal women. Among premenopausal luteal phase women, the 16-pathway metabolite estriol was associated with percent area (p = 0.04) and volume (p = 0.05) mammographic densities and absolute area (p = 0.02) and volume (p = 0.05) densities. Among postmenopausal women, levels of total estrogens, the sum of parent estrogens, and 2-, 4- and 16-hydroxylation pathway metabolites were positively associated with area density measures (percent: p = 0.03, p = 0.04, p = 0.01, p = 0.02, p = 0.07; absolute: p = 0.02, p = 0.02, p = 0.01, p = 0.02, p = 0.03, respectively) but not volume density measures. Our data suggest that serum estrogen profiles are weak determinants of mammographic density and that analysis of different density metrics may provide complementary information about relationships of estrogen exposure to breast tissue composition.

Melanocytic nevi as biomarkers of breast cancer risk

In a linked Perspective, Barbara Fuhrman and Victor Cardenas discuss the potential biological mechanisms that may underlie the association between nevi and risk for breast cancer. Please see later in the article for the Editors' Summary

Fecal microbial determinants of fecal and systemic estrogens and estrogen metabolites: a cross-sectional study

Background

High systemic estrogen levels contribute to breast cancer risk for postmenopausal women, whereas low levels contribute to osteoporosis risk. Except for obesity, determinants of non-ovarian systemic estrogen levels are undefined. We sought to identify members and functions of the intestinal microbial community associated with estrogen levels via enterohepatic recirculation.

Methods

Fifty-one epidemiologists at the National Institutes of Health, including 25 men, 7 postmenopausal women, and 19 premenopausal women, provided urine and aliquots of feces, using methods proven to yield accurate and reproducible results. Estradiol, estrone, 13 estrogen metabolites (EM), and their sum (total estrogens) were quantified in urine and feces by liquid chromatography/tandem mass spectrometry. In feces, β-glucuronidase and β-glucosidase activities were determined by realtime kinetics, and microbiome diversity and taxonomy were estimated by pyrosequencing 16S rRNA amplicons. Pearson correlations were computed for each log_e estrogen level, log_e enzymatic activity level, and microbiome alpha diversity estimate. For the 55 taxa with mean relative abundance of at least 0.1%, ordinal levels were created [zero, low (below median of detected sequences), high] and compared to log_e estrogens, β-glucuronidase and β-glucosidase enzymatic activity levels by linear regression. Significance was based on two-sided tests with α=0.05.

Results

In men and postmenopausal women, levels of total urinary estrogens (as well as most individual EM) were very strongly and directly associated with all measures of fecal microbiome richness and alpha diversity (R≥0.50, P≤0.003). These non-ovarian systemic estrogens also were strongly and significantly associated with fecal Clostridia taxa, including non-Clostridiales and three genera in the Ruminococcaceae family (R=0.57−0.70, P=0.03−0.002). Estrone, but not other EM, in urine correlated significantly with functional activity of fecal β-glucuronidase (R=0.36, P=0.04). In contrast, fecal β-glucuronidase correlated inversely with fecal total estrogens, both conjugated and deconjugated (R≤-0.47, P≤0.01). Premenopausal female estrogen levels, which were collected across menstrual cycles and thus highly variable, were completely unrelated to fecal microbiome and enzyme parameters (P≥0.6).

Conclusions

Intestinal microbial richness and functions, including but not limited to β-glucuronidase, influence levels of non-ovarian estrogens via enterohepatic circulation. Thus, the gut microbial community likely affects the risk for estrogen-related conditions in older adults. Understanding how Clostridia taxa relate to systemic estrogens may identify targets for interventions.

Trial registration

Not applicable.

Fasting glucose and treatment outcome in breast and colorectal cancer patients treated with targeted agents: results from a historic cohort

BACKGROUND

We investigated pretreatment fasting glucose as a predictor of patients' important outcomes in breast and colorectal cancers undergoing targeted therapies.

PATIENTS AND METHODS

In a historic cohort of 202 breast and 218 colorectal cancers treated with targeted agents from 1998 to 2009, we used the Kaplan-Meier method and the log-rank test to estimate survival through tertiles of fasting glucose and the Cox proportional hazards model for multivariate analysis stratified by primary site of cancer and including gender, age and body mass index.

RESULTS

The median follow-up was 20 months (1-128). At 60 months, 65% of patients in the lowest tertile of fasting glucose did not experiment disease progression compared with 34% in the highest tertile (P=0.001). Seventy-six percent of females in the lowest tertile showed no progression compared with 49% in the top tertiles (P=0.015). In multivariate analysis, fasting glucose was a significant predictor of time to disease progression only in breast cancer patients in the first tertile compared with the third (P=0.017).

CONCLUSIONS

We found evidence of a predictive role of pretreatment fasting glucose in the development of resistance in breast cancer patients treated with targeted agents. Prospective studies are warranted to confirm our findings.

Sunlight, hormone replacement status and colorectal cancer risk in postmenopausal women

A reanalysis of the Women's Health Initiative (WHI) randomized clinical trial found a significant interaction between supplementation with vitamin D/calcium and estrogen therapy and the risk of colorectal cancer risk, with reduced risks from supplementation limited to the placebo arms of the estrogen trials. To explore whether the vitamin D effects are modified by estrogen therapy, we report a largely cross-sectional, analysis of the association between sun exposure, which is an important vitamin D source, and colorectal cancer risk among postmenopausal women in the U.S. Radiologic Technologists study. Among 21,695 participants, there were a total of 108 cases. Sun exposure was based on time outdoors and on ambient ultraviolet radiation (UV) exposure based on residence linked to erythemal exposures derived from the Total Ozone Mapping Spectrometer database. Although there was no relationship between outdoor time or ambient UV measure and colorectal cancer risk in current hormone replacement therapy (HRT) users, in never/past HRT users, there was an inverse association with higher ambient UV exposure, RR for highest vs. lowest tertile = 0.40; 95% CI 017, 0.93; p for trend = 0.04. Non-significant lower risks were also associated with higher levels of outdoor time (> or = 3.5 hr/week) in never/past HRT users. The interaction between both indicators of sun exposure and HRT and CRC risk was not significant. These data, although exploratory, are consistent with evidence from the WHI suggesting a decrease in colorectal cancer risk may be associated with vitamin D exposure among postmenopausal women who are not taking HRT, but not among current HRT users.

In Asian-American Women, Westernization Influences Estrogen Metabolism, but Not Total Endogenous Estrogen Production

Background: Historically, breast cancer incidence rates were 4-7 times higher in the United States than in China and Japan. When Asian women migrate to the U.S., their risk rises over several generations and approaches that in U.S. Whites. Endogenous estrogen has been postulated to explain these international differences. Methods: In a population-based case-control study in Chinese, Japanese, and Filipino women living in San Francisco-Oakland, CA; Los Angeles, CA; or Oahu, HI, we documented a six-fold gradient in breast cancer risk with Westernization. Using 12-h, overnight urines from 263 premenopausal mid-luteal and 168 postmenopausal control subjects, we investigated associations of estrogens and estrogen metabolites (EM) with Westernization, particularly birthplace in the East or West. Fifteen EM were measured concurrently by liquid chromatography-tandem mass spectrometry with high accuracy, precision, and sensitivity. Log-transformed EM measures, adjusted for age and ethnicity, were compared by robust linear regression. Results: Total urinary EM (pmol/mg creatinine) was not associated with birthplace in premenopausal or postmenopausal women. When the three estrogen hydroxylation pathways were expressed as percent of total EM, the relative difference by birthplace, West compared to East, was 15% lower for 2-pathway EM (p=0.009), 7% lower for 4-pathway EM (p=0.37), and 10% higher for 16-pathway EM (p=0.008). Similar results were observed for individual EM in each pathway, premenopausal and postmenopausal women, and the three ethnicities. In both menopausal groups, 2-pathway EM concentration decreased steadily with increasing risk across six categories of Westernization. Conclusions: Our results do not indicate that total estrogen production explains the increased breast cancer risk in Western societies. However, estrogen metabolism patterns, especially reduced 2-hydroxylation, may contribute to the elevated risk; and underlying mechanisms merit further exploration.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3063.

Abstract B126: Does adult soy intake influence total estrogen levels and estrogen metabolism patterns?

B126

Background

Soy foods are a dietary staple in Asian countries and may play a role in this region’s historically low rates of breast cancer incidence. Isoflavones found in soy have structural similarities to estrogens and could exert protective effects by interacting with estrogen receptors, binding proteins, or metabolic enzymes. In a sample of Asian-American women we test whether soy is associated with urinary concentrations of estrogens and estrogen metabolites (EM).

Methods

This analysis was conducted among controls from a population-based case-control study of breast cancer among women of Chinese, Japanese and Filipino ancestry, aged 20-55 years, and living in San Francisco-Oakland (CA), Los Angeles (CA) and Oahu (HI). Of 966 controls, we included the 571 (59%) women who donated a 12-hour urine and had not been pregnant or lactating or used exogenous hormones in the last 6 months. At urine collection, 168 women were postmenopausal, 233 were pre-menopausal in mid-luteal phase, and 170 were in other categories. Fifteen EM were measured simultaneously with a highly sensitive and reproducible liquid chromatography-tandem mass spectrometry method. Participants had been queried about their usual adult frequency of intake of tofu and other selected soy foods. Robust regression was used to model the associations of soy intake (in tertiles) with EM measures. Models were adjusted for age, ethnicity, body mass index (BMI), and birthplace (Asia/West).

Results

No statistically significant associations were seen between soy intake and urinary concentrations of estrone, estradiol, estriol, or total EM in postmenopausal women or premenopausal women. In postmenopausal but not premenopausal women, we found significant trends across tertiles of soy intake for EM grouped by metabolic pathways. The 2- and 4-hydroxylated EM and the methylated catechols, each expressed as a percent of total EM, increased with soy intake, while relative levels of EM in the 16-hydroxylation pathway decreased. Models adjusted for age and ethnicity were similar. Factor analysis was used to confirm EM groupings. Among postmenopausal women, factor analysis identified four independent EM patterns, termed ‘catechols’, ‘methylated catechols’, ‘16-hydroxylation pathway EM’, and ‘parent estrogens’ based on the predominant EM. Factors for premenopausal women were similar.

Discussion

Our findings do not support the hypothesis that soy intake influences endogenous production of estrogens but they do suggest that soy intake can modify estrogen metabolism in postmenopausal women. Increased ratios of 2-hydroxyestrone to 16α-hydroxyestrone have been associated with lower breast cancer risk in some epidemiologic studies. Methylation of catechol estrogens results in deactivation of these metabolites and prevents conversion into genotoxic quinones. Thus, the trends by soy intake represent variations in EM metabolism that could reduce breast cancer risk.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):B126.

Perinatal exposures and breast cancer risk in the Western New York Exposures and Breast Cancer (WEB) Study

BACKGROUND

There is increasing evidence that early life exposures, such as birth weight, infant feeding practices, birth rank and maternal age at delivery may play a role in breast carcinogenesis.

METHODS

We conducted a case-control study of women aged 35-80 in Western New York (Western New York Exposure and Breast Cancer Study, the WEB Study, 1996-2001). The study included 845 women diagnosed with primary, incident, histologically confirmed breast cancer, and 1538 controls frequency-matched to cases on age, race, and county of residence. We conducted extensive in-person interviews including self-reported birth weight, history of having been breastfed, birth rank, and maternal age at delivery.

RESULTS

Birth weight was significantly associated with pre- but not post-menopausal breast cancer risk. Compared to women whose birth weight was 5.5-7 pounds, we found an increased risk associated with a birth weight greater than 8.5 pounds (OR 1.84, 95%CI: 1.12-3.02). Risk was also increased for pre- but not post-menopausal women who had not been breastfed (OR 1.78, 95%CI: 1.21-2.60). Birth order and maternal age at delivery were not significantly associated with breast cancer risk.

CONCLUSIONS

Our findings are consistent with other studies showing breast cancer risk associated with birth weight for pre- but not post-menopausal breast cancer. As we found in an earlier study, having been breastfed was associated with decreased risk. These findings add to the accumulating evidence that early life events impact women's subsequent breast cancer risk.

Association between cigarette smoking and prognosis in locally advanced cervical carcinoma treated with chemoradiation: a Gynecologic Oncology Group study

OBJECTIVE

To determine if smoking, a known risk factor for a number of cancers including cervical cancer, is associated with poor prognosis in patients with locally advanced cervical carcinoma treated with chemoradiation.

METHODS

Patients with primary, previously untreated, histologically confirmed stage II-B, III-B or IV-A cervical carcinoma participated in a Gynecologic Oncology Group (GOG) phase III study (GOG 165) and were randomly allocated to receive radiation plus either cisplatin or 5-fluorouracil. Smoking behavior was ascertained using an administered questionnaire and by quantifying urine cotinine concentration. Disease progression was defined as a >or=50% increase in the cross product of the existing tumor compared with previous assessments. Patients were followed until death.

RESULTS

Of 328 enrolled patients, 12 were ineligible, one was inevaluable for reported smoking status and 40 others were inevaluable for cotinine-derived smoking status. Among evaluable patients, 133 (42%) were reported smokers and 111 (40%) were cotinine-derived smokers. The kappa for agreement between the groups was 0.872 (P<0.01). Compared with non-smokers, median survival was 15 months shorter for reported smokers and 20 months shorter for cotinine-derived smokers (P<0.01). After adjusting for covariates, a significant increase in the risk of death (but not disease progression) was observed for reported smokers (hazard ratio [HR]: 1.51; 95% confidence interval [CI]: 1.01-2.27; P=0.04) and cotinine-derived smokers (HR: 1.57; 95% CI: 1.03-2.38; P=0.04).

CONCLUSIONS

Smoking predicts worse overall survival in women with locally advanced cervical carcinoma treated with chemoradiation.

Basal growth hormone concentrations in blood and the risk for prostate cancer: a case-control study

OBJECTIVE

To assess the relationship between basal serum growth hormone (GH) levels and prostate cancer risk.

METHODS

We conducted a population-based case-control study; cases included 68 men, aged 45-85 years, diagnosed with incident, primary, histologically confirmed, and clinically apparent (stage B and higher) prostate cancer. Controls included 240 men, frequency matched on age and residential area. Age, race, BMI, waist circumference, history of enlarged prostate, education, and current smoking status, were all considered as possible confounders.

RESULTS

We found a statistically significant trend of decreasing prostate cancer risk across increasing GH quintiles, in both crude (OR: 0.31, 95% CI: 0.12-0.83, P for trend 0.01) and adjusted models (OR: 0.35, 95% CI: 0.12-1.05, P for trend 0.03), in the highest compared to the lowest quintile, respectively.

CONCLUSIONS

Lower basal levels of GH in serum are associated with increased prostate cancer risk. The inverse association may be explained by the negative feedback loop generated by IGF-1 produced by the tumor on GH secretion.

Dietary antioxidants and paraoxonases against LDL oxidation and atherosclerosis development

Oxidative modification of low-density lipoprotein (LDL) in the arterial wall plays a key role in the pathogenesis of atherosclerosis. Under oxidative stress LDL is exposed to oxidative modifications by arterial wall cells including macrophages. Oxidative stress also induces cellular-lipid peroxidation, resulting in the formation of 'oxidized macrophages', which demonstrate increased capacity to oxidize LDL and increased uptake of oxidized LDL. Macrophage-mediated oxidation of LDL depends on the balance between pro-oxidants and antioxidants in the lipoprotein and in the cells. LDL is protected from oxidation by antioxidants, as well as by a second line of defense--paraoxonase 1 (PON1), which is a high-density lipoprotein-associated esterase that can hydrolyze and reduce lipid peroxides in lipoproteins and in arterial cells. Cellular paraoxonases (PON2 and PON3) may also play an important protective role against oxidative stress at the cellular level. Many epidemiological studies have indicated a protective role for a diet rich in fruits and vegetables against the development and progression of cardiovascular disease. A large number of studies provide data suggesting that consumption of dietary antioxidants is associated with reduced risk for cardiovascular diseases. Basic research provides plausible mechanisms by which dietary antioxidants might reduce the development of atherosclerosis. These mechanisms include inhibition of LDL oxidation, inhibition of cellular lipid peroxidation and consequently attenuation of cell-mediated oxidation of LDL. An additional possible mechanism is preservation/increment of paraoxonases activity by dietary antioxidants. This review chapter presents recent data on the anti-atherosclerotic effects and mechanism of action of three major groups of dietary antioxidants-vitamin E, carotenoids and polyphenolic flavonoids.

Lifetime total and beverage specific--alcohol intake and prostate cancer risk: a case-control study

Background

We investigated lifetime alcohol consumption and prostate cancer risk in a case-control study conducted in Buffalo, NY (1998–2001).

Methods

The study included 88 men, aged 45 to 85 years with incident, histologically-confirmed prostate cancer and 272 controls. We conducted extensive in-person interviews regarding lifetime alcohol consumption and other epidemiologic data.

Results

Prostate cancer risk was not associated with lifetime intake of total and beverage specific ethanol. In addition we found no association with number of drinks per day (average drinks per day over the lifetime) or drinks per drinking day (average drinks per day on drinking days only over the lifetime). However, we observed an inverse association with the total number of drinking years. Men in the lowest tertile of total drinking years had a two-fold prostate cancer risk than men in the highest tertile (OR 2.16, 95% CI 0.98–4.78, p for trend <0.05).

Conclusion

Our results suggest that alcohol intake distribution across lifetime may play a more important role in prostate cancer etiology than total lifetime consumption.

The antioxidative effect of the bacteria Dienococcus radiophilus against LDL lipid peroxidation

BACKGROUND

Lipid peroxidation is an important process in the development of atherosclerosis. Thus agents with antioxidant properties may play an important role in the inhibition of atherosclerosis.

OBJECTIVES

In this study we aimed to show that the lipid extract of the bacteria Deinococcus radiophilus (leDR) has antioxidant properties against LDL oxidation.

RESULTS

This antioxidant effect was shown in both transition metal ion and free radical generating systems. We also showed that leDR can protect LDL from UV light-induced oxidative damage. The antioxidative capacity of leDR is partly due to copper ion chelation.

CONCLUSION

We conclude that some specific bacteria constituent has the ability to inhibit LDL oxidation and, thus, to attenuate atherogenesis.

Pomegranate juice flavonoids inhibit low-density lipoprotein oxidation and cardiovascular diseases: studies in atherosclerotic mice and in humans

The beneficial health effects attributed to the consumption of fruit and vegetables are related, at least in part, to their antioxidant activity. Of special interest is the inverse relationship between the intake of dietary nutrients rich in polyphenols and cardiovascular diseases. This effect is attributed to polyphenols' ability to inhibit low-density lipoprotein (LDL) oxidation, macrophage foam cell formation and atherosclerosis. Pomegranate polyphenols can protect LDL against cell-mediated oxidation via two pathways, including either direct interaction of the polyphenols with the lipoprotein and/or an indirect effect through accumulation of polyphenols in arterial macrophages. Pomegranate polyphenols were shown to reduce the capacity of macrophages to oxidatively modify LDL, due to their interaction with LDL to inhibit its oxidation by scavenging reactive oxygen species and reactive nitrogen species and also due to accumulation of polyphenols in arterial macrophages; hence, the inhibition of macrophage lipid peroxidation and the formation of lipid peroxide-rich macrophages. Furthermore, pomegranate polyphenols increase serum paraoxonase activity, resulting in the hydrolysis of lipid peroxides in oxidized lipoproteins and in atherosclerotic lesions. These antioxidative and antiatherogenic effects of pomegranate polyphenols were demonstrated in vitro, as well as in vivo in humans and in atherosclerotic apolipoprotein E deficient mice. Dietary supplementation of polyphenol-rich pomegranate juice to atherosclerotic mice significantly inhibited the development of atherosclerotic lesions and this may be attributed to the protection of LDL against oxidation.

White wine with red wine-like properties: increased extraction of grape skin polyphenols improves the antioxidant capacity of the derived white wine

Lower antioxidant activity in white wines in comparison to red wines lies in the low grape-skin-derived polyphenol content. This paper reports the analysis of the antioxidant capacities of white wine samples obtained along two different processing procedures directed to enrich the wine with polyphenols. White wine samples derived from whole squeezed grapes stored for increasing periods of time (up to 18 h) contained increasing concentrations of polyphenols (from 0.35 to 0.55 mmol/L) and, in parallel, exhibited increased capacity to scavenge free radicals and to inhibit copper ion-induced low-density lipoprotein (LDL) oxidation. However, addition of increasing concentrations of alcohol (up to 18%) to the whole squeezed grapes remarkably augmented the extraction of grape skin polyphenols into the wine up to 1.25 mmol/L, resulting in an increased capacity of the wine to scavenge free radicals and to inhibit LDL oxidation, to an extent similar to that of red wine. The extent of LDL oxidation inhibition was directly related to the wine polyphenolic content (r = 0.986). It is concluded that processing white wine by imposing a short period of grape skin contact in the presence of alcohol leads to extraction of grape skin polyphenols and produces polyphenol-rich white wine with antioxidant characteristics similar to those of red wine.

Flavonoids protect LDL from oxidation and attenuate atherosclerosis

Consumption of some plant-derived flavonoids results in their absorption and appearance in plasma and tissues. The inverse relationship between dietary flavonoids consumption and cardiovascular diseases may be associated with the ability of flavonoids to attenuate LDL oxidation, macrophage foam cell formation and atherosclerosis. The effect of flavonoids on arterial cell-mediated oxidation of LDL is determined by their accumulation in the lipoprotein and in arterial cells, such as macrophages. Flavonoids can reduce LDL lipid peroxidation by scavenging reactive oxygen/nitrogen species, chelation of transition metal ions and sparing of LDL-associated antioxidants. They can also reduce macrophage oxidative stress by inhibition of cellular oxygenases [such as nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) oxidase] or by activating cellular antioxidants (such as the glutathione system). Thus, plant flavonoids, as potent natural antioxidants that protect against lipid peroxidation in arterial cells and lipoproteins, significantly attenuate the development of atherosclerosis.

Anti-atherogenicity of nutritional antioxidants

Epidemiological studies have indicated that fruit- and vegetable-rich diets play a protective role against cardiovascular disease. An explanation for this protection lies in the presence of antioxidant vitamins in fruits and vegetables. A large number of studies have provided data suggesting that consumption of dietary antioxidants is associated with reduced risk for cardiovascular disease. Plausible mechanisms by which these antioxidants may reduce the development of atherosclerosis include inhibition of low-density lipoprotein (LDL) oxidation, cellular lipid peroxidation and cell-mediated oxidation of LDL, and reduction in blood cholesterol levels. This review reports on the recent data of the anti-atherosclerotic effects and mechanistical aspects of three major groups of dietary antioxidants: vitamin E, carotenoids and flavonoids.

Pomegranate juice consumption reduces oxidative stress, atherogenic modifications to LDL, and platelet aggregation: studies in humans and in atherosclerotic apolipoprotein E-deficient mice

BACKGROUND

Dietary supplementation with nutrients rich in antioxidants is associated with inhibition of atherogenic modifications to LDL, macrophage foam cell formation, and atherosclerosis. Pomegranates are a source of polyphenols and other antioxidants.

OBJECTIVE

We analyzed, in healthy male volunteers and in atherosclerotic apolipoprotein E-deficient (E(0)) mice, the effect of pomegranate juice consumption on lipoprotein oxidation, aggregation, and retention; macrophage atherogenicity; platelet aggregation; and atherosclerosis.

DESIGN

Potent antioxidative effects of pomegranate juice against lipid peroxidation in whole plasma and in isolated lipoproteins (HDL and LDL) were assessed in humans and in E(0) mice after pomegranate juice consumption for </=2 and 14 wk, respectively.

RESULTS

In humans, pomegranate juice consumption decreased LDL susceptibility to aggregation and retention and increased the activity of serum paraoxonase (an HDL-associated esterase that can protect against lipid peroxidation) by 20%. In E(0) mice, oxidation of LDL by peritoneal macrophages was reduced by up to 90% after pomegranate juice consumption and this effect was associated with reduced cellular lipid peroxidation and superoxide release. The uptake of oxidized LDL and native LDL by mouse peritoneal macrophages obtained after pomegranate juice administration was reduced by 20%. Finally, pomegranate juice supplementation of E(0) mice reduced the size of their atherosclerotic lesions by 44% and also the number of foam cells compared with control E(0) mice supplemented with water.

CONCLUSION

Pomegranate juice had potent antiatherogenic effects in healthy humans and in atherosclerotic mice that may be attributable to its antioxidative properties.

Ginger extract consumption reduces plasma cholesterol, inhibits LDL oxidation and attenuates development of atherosclerosis in atherosclerotic, apolipoprotein E-deficient mice

Oxidative modification of LDL is thought to play a key role in the pathogenesis of atherosclerosis. Consumption of nutrients rich in phenolic antioxidants has been shown to be associated with attenuation of development of atherosclerosis. This study was undertaken to investigate the ex vivo effect of standardized ginger extract on the development of atherosclerosis in apolipoprotein E-deficient (E(0)) mice, in relation to plasma cholesterol levels and the resistance of their LDL to oxidation and aggregation. E(0) mice (n = 60; 6-wk-old) were divided into three groups of 20 and fed for 10 wk via their drinking water with the following: group i) placebo (control group), 1.1% alcohol and water (11 mL of alcohol in 1 L of water); group ii) 25 microg of ginger extract/d in 1.1% alcohol and water and group iii) 250 microg of ginger extract/day in 1.1% alcohol and water. Aortic atherosclerotic lesion areas were reduced 44% (P<0.01) in mice that consumed 250 microg of ginger extract/day. Consumption of 250 microg of ginger extract/day resulted in reductions (P<0.01) in plasma triglycerides and cholesterol (by 27 and 29%, respectively), in VLDL (by 36 and 53%, respectively) and in LDL (by 58 and 33%, respectively). These results were associated with a 76% reduction in cellular cholesterol biosynthesis rate in peritoneal macrophages derived from the E(0) mice that consumed the high dose of ginger extract for 10 wk (P<0.01). Furthermore, peritoneal macrophages harvested from E(0) mice after consumption of 25 or 250 microg of ginger extract/day had a lower (P<0.01) capacity to oxidize LDL (by 45 and by 60%, respectively), and to take up and degrade oxidized LDL (by 43 and 47%, respectively). Consumption of 250 microg of ginger extract/day also reduced (P<0.01) the basal level of LDL-associated lipid peroxides by 62%. In parallel, a 33% inhibition (P<0.01) in LDL aggregation (induced by vortexing) was obtained in mice fed ginger extract. We conclude that dietary consumption of ginger extract by E(0) mice significantly attenuates the development of atherosclerotic lesions. This antiatherogenic effect is associated with a significant reduction in plasma and LDL cholesterol levels and a significant reduction in the LDL basal oxidative state, as well as their susceptibility to oxidation and aggregation.

Lycopene synergistically inhibits LDL oxidation in combination with vitamin E, glabridin, rosmarinic acid, carnosic acid, or garlic

Several lines of evidence suggest that oxidatively modified low-density lipoprotein (LDL) is atherogenic, and that atherosclerosis can be attenuated by natural antioxidants, which inhibit LDL oxidation. This study was conducted to determine the effect of tomato lycopene alone, or in combination with other natural antioxidants, on LDL oxidation. LDL (100 microg of protein/ml) was incubated with increasing concentrations of lycopene or of tomato oleoresin (lipid extract of tomatoes containing 6% lycopene, 0.1% beta-carotene, 1% vitamin E, and polyphenols), after which it was oxidized by the addition of 5 micromol/liter of CuSO4. Tomato oleoresin exhibited superior capacity to inhibit LDL oxidation in comparison to pure lycopene, by up to five-fold [97% vs. 22% inhibition of thiobarbituric acid reactive substances (TBARS) formation, and 93% vs. 27% inhibition of lipid peroxides formation, respectively]. Because tomato oleoresin also contains, in addition to lycopene, vitamin E, flavonoids, and phenolics, a possible cooperative interaction between lycopene and such natural antioxidants was studied. A combination of lycopene (5 micromol/liter) with vitamin E (alpha-tocopherol) in the concentration range of 1-10 micromol/liter resulted in an inhibition of copper ion-induced LDL oxidation that was significantly greater than the expected additive individual inhibitions. The synergistic antioxidative effect of lycopene with vitamin E was not shared by gamma-to-cotrienol. The polyphenols glabridin (derived from licorice), rosmarinic acid or carnosic acid (derived from rosemary), as well as garlic (which contains a mixture of natural antioxidants) inhibited LDL oxidation in a dose-dependent manner. When lycopene (5 micromol/liter) was added to LDL in combination with glabridin, rosmarinic acid, carnosic acid, or garlic, synergistic antioxidative effects were obtained against LDL oxidation induced either by copper ions or by the radical generator AAPH. Similar interactive effects seen with lycopene were also observed with beta-carotene, but, however, to a lesser extent of synergism. Because natural antioxidants exist in nature in combination, the in vivo relevance of lycopene in combination with other natural antioxidants was studied. Four healthy subjects were administered a fatty meal containing 30 mg of lycopene in the form of tomato oleoresin. The lycopene concentration in postprandial plasma was elevated by 70% in comparison to plasma obtained before meal consumption. Postprandial LDL isolated 5 hr after meal consumption exhibited a significant (p < 0.01) reduced susceptibility to oxidation by 21%. We conclude that lycopene acts synergistically, as an effective antioxidant against LDL oxidation, with several natural antioxidants such as vitamin E, the flavonoid glabridin, the phenolics rosmarinic acid and carnosic acid, and garlic. These observations suggest a superior antiatherogenic characteristic to a combination of different natural antioxidants over that of an individual one.

LDL oxidation by arterial wall macrophages depends on the oxidative status in the lipoprotein and in the cells: role of prooxidants vs. antioxidants

Oxidized LDL is highly atherogenic as it stimulates macrophage cholesterol accumulation and foam cell formation, it is cytotoxic to cells of the arterial wall and it stimulates inflammatory and thrombotic processes. LDL oxidation can lead to its subsequent aggregation, which further increases cellular cholesterol accumulation. All major cells in the arterial wall including endothelial cells, smooth muscle cells and monocyte derived macrophages can oxidize LDL. Macrophage-mediated oxidation of LDL is probably a hallmark in early atherosclerosis, and it depends on the oxidative state of the LDL and that of the macrophages. The LDL oxidative state is elevated by increased ratio of poly/mono unsaturated fatty acids, and it is reduced by elevation of LDL-associated antioxidants such as vitamin E, beta-carotene, lycopene, and polyphenolic flavonoids. The macrophage oxidative state depends on the balance between cellular NADPH-oxidase and the glutathione system. LDL-associated polyphenolic flavonoids which inhibit its oxidation, can also reduce macrophage oxidative state, and subsequently the cell-mediated oxidation of LDL. Oxidation of the macrophage lipids, which occurs under oxidative stress, can lead to cell-mediated oxidation of LDL even in the absence of transition metal ions, and may be operable in vivo. Finally, elimination of Ox-LDL from extracellular spaces, after it was formed under excessive oxidative stress, can possibly be achieved by the hydrolytic action of HDL-associated paraoxonase on lipoprotein's lipid peroxides. The present review article summarizes the above issues with an emphasis on our own data.

Polyphenolic flavonoids inhibit macrophage-mediated oxidation of LDL and attenuate atherogenesis

Macrophage-mediated oxidation of LDL, a hallmark in early atherosclerosis, depends on the oxidative state of the LDL, and that of the macrophages. The LDL oxidative state is determined by the balance between the LDL polyunsaturated fatty acids and cholesterol, which are prone to oxidation, and the LDL associated antioxidants. Dietary consumption of nutrients rich in polyphenols, such as red wine or liquorice results in LDL enrichment with these polyphenolic flavonoids, and hence, subsequent LDL oxidation is reduced. In addition, enrichment of LDL with polyphenols results in a marked decrease in the susceptibility of the lipoprotein to aggregation (another lipoprotein atherogenic modification). The oxidative status of the macrophages depends on the balance between cellular oxygenases and antioxidants. Macrophage enrichment with polyphenolic flavonoids in vitro or in vivo also reduce macrophage oxidative state, and subsequently cell-mediated oxidation of LDL. The present review article summarizes our current data on these aspects of the antiatherogenic potential of polyphenolic flavonoids.

The antioxidative effects of the isoflavan glabridin on endogenous constituents of LDL during its oxidation

The effect of the consumption of glabridin, an isoflavan isolated from Glycyrrhiza glabra (licorice) root, on the susceptibility of low density lipoprotein (LDL) to oxidation was studied in atherosclerotic apolipoprotein E deficient (E[o] mice) and was compared with that of the known flavonoids, quercetin and catechin. Glabridin inhibitory activity on in vitro oxidation of human LDL was also investigated by determining the formation of lipid peroxides and oxysterols and the consumption of LDL-associated lipophilic antioxidants. Determination of the extent of LDL oxidation by measuring the formation of thiobabituric acid reactive substances (TBARS) after 2 h of LDL incubation with CuSO4 (10 microM) or 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH) (5 mM), revealed that glabridin or quercetin consumption resulted in a 53 and 54% reduction in copper ion induced oxidation, respectively, and a 95 and 83% reduction in AAPH induced LDL oxidation, respectively. No inhibition was obtained with consumption of catechin. About 80% of glabridin was found to bind to the LDL human particle. In the in vitro oxidation of LDL induced by AAPH (5 mM), glabridin inhibited the formation of TBARS, lipid peroxides and cholesteryl linoleate hydroperoxide (CLOOH) at all the concentrations tested (5-60 microM), while in oxidation induced by copper ions (10 microM), glabridin exhibited a pro-oxidant activity at concentrations lower than 20 microM, and a clear antioxidant activity at concentrations greater than 20 microM. Glabridin (30 microM) inhibited the formation of cholest-5-ene-3,7-diol (7-hydroxycholesterol), cholest-5-ene-3-ol-7-one (7-ketocholesterol) and cholestan-5,6-epoxy-3-ol (5,6-epoxycholesterol) after 6 h of AAPH induced LDL oxidation, by 55, 80 and 40%, respectively, and after 6 h of copper ion induced LDL oxidation, by 73, 94 and 52%, respectively. Glabridin also inhibited the consumption of beta-carotene and lycopene by 38 and 52%, respectively, after 0.5 h of LDL oxidation with AAPH, but failed to protect vitamin E. The in vivo and in vitro reduction of the susceptibility of LDL to oxidation obtained with glabridin, may be related to the absorption or binding of glabridin to the LDL particle and subsequent protection of LDL from oxidation by inhibiting the formation of lipid peroxides and oxysterols, and by protecting LDL associated carotenoids.

Reduced progression of atherosclerosis in apolipoprotein E-deficient mice following consumption of red wine, or its polyphenols quercetin or catechin, is associated with reduced susceptibility of LDL to oxidation and aggregation

The effect of consuming red wine, or its major polyphenol constituents catechin or quercetin, on the development of atherosclerotic lesions, in relation to the susceptibility of plasma LDL to oxidation and to aggregation, was studied in atherosclerotic apolipoprotein E deficient (E degree) mice. Forty E degree mice at the age of 4 weeks were divided into four groups, 10 mice in each group, and were supplemented for up to 6 weeks in their drinking water with placebo (1.1% alcohol); catechin or quercetin (50 micrograms/d per mouse), or red wine (0.5 mL/d per mouse). Consumption of catechin, quercetin, or red wine had no effect on plasma LDL or HDL cholesterol levels. The atherosclerotic lesion area was smaller in the treated mice by 39%, 46%, and 48%, respectively, in comparison with E degree mice that were treated with placebo. In accordance with these findings, cellular uptake of LDL derived after catechin, quercetin, or red wine consumption was found to be reduced by 31%, 40%, and 52%, respectively. These results were associated with reduced susceptibility to oxidation (induced by different modes such as copper ions, free radical generator, or macrophages) of LDL isolated after red wine or quercetin and, to a lesser extent after catechin consumption, in comparison with LDL isolated from the placebo group. Similar results were obtained when LDL was preincubated in vitro with red wine or with the polyphenols prior to its oxidation. Even in the basal oxidative state (not induced oxidation), LDL isolated from E degree mice that consumed catechin, quercetin, or red wine for 2 weeks was found to be less oxidized in comparison with LDL isolated from E degree mice that received placebo, as evidenced by 39%, 48%, and 49% reduced content of LDL-associated lipid peroxides, respectively. This effect could be related to enhanced serum paraoxonase activity in the polyphenol-treated mice. LDL oxidation was previously shown to lead to its aggregation. The present study demonstrated that the susceptibility of LDL to aggregation was reduced in comparison with placebo-treated mice, by 63%, 48%, or 50% by catechin, quercetin, and red wine consumption, respectively, and this effect could be shown also in vitro. The inhibition of LDL oxidation by polyphenols could be related, at least in part, to a direct effect of the polyphenols on the LDL, since both quercetin and catechin were found to bind to the LDL particle via the formation of an ether bond. We thus conclude that dietary consumption by E degree mice of red wine or its polyphenolic flavonoids quercetin and, to a lesser extent, catechin leads to attenuation in the development of the atherosclerotic lesion, and this effect is associated with reduced susceptibility of their LDL to oxidation and aggregation.

Licorice extract and its major polyphenol glabridin protect low-density lipoprotein against lipid peroxidation: in vitro and ex vivo studies in humans and in atherosclerotic apolipoprotein E-deficient mice

Polyphenolic flavonoids are powerful antioxidants. In the present study we investigated the antioxidative activity against low-density-lipoprotein (LDL) oxidation of a not yet studied subclass of polyphenols, the isoflavans, which are present in licorice alcoholic extract. The study was performed in humans as well as in atherosclerotic apolipoprotein E-deficient mice (E zero), because their LDL is highly susceptible to oxidation. LDL oxidation was induced by incubating it with copper ions as well as with the aqueous or lipid-soluble free radical generators 2,2'-azobis'2-amidino propane hydrochloride (AAPH) and 2,2'-azobis 2,4-dimethylvaleronitrile (AMVN), respectively. The extent of LDL oxidation was determined by measuring the formation of conjugated dienes, thiobarbituric acid reactive-substances (TBARS), and lipid peroxides. By all methods in human studies, licorice ethanolic extract as well as a pure material, which was identified by gas chromatography-mass spectroscopy as the isoflavan glabridin, were shown to inhibit LDL oxidation by a mechanism involving scavenging of free radicals. In an ex vivo study, LDL isolated from the plasma of 10 normolipidemic subjects who were orally supplemented for 2 wk with 100 mg licorice/d was more resistant to oxidation than was LDL isolated before licorice supplementation. Dietary supplementation of each E zero mouse with licorice (200 micrograms/d) or pure glabridin (20 micrograms/d) for 6 wk resulted in a substantial reduction in the susceptibility of their LDL to oxidation along with a reduction in the atherosclerotic lesion area. These results could be related to the absorption and binding of glabridin to the LDL particle and subsequent protection of the LDL from oxidation by multiple modes as shown in humans and in E zero mice.

Hypocholesterolemic effect of lycopene and beta-carotene is related to suppression of cholesterol synthesis and augmentation of LDL receptor activity in macrophages

Beta-Carotene and lycopene are derived from plants, and they share similar initial synthetic pathway with cholesterol, which is synthesized in animal but not in plant cells. Thus, we sought to analyze the effect of carotenoids on macrophage cholesterol metabolism, in comparison to the effect of LDL cholesterol and of the cholesterol synthesis inhibitor, fluvastatin. In J-774 A. 1 macrophage cell line, the cellular cholesterol synthesis from [3H]-acetate, but not from [14C] mevalonate, was suppressed by 63% any by 73% following cell incubation with beta-carotene or lycopene (10 microM) respectively, in comparison to a 90% and 91% inhibition by LDL (100 micrograms of cholesterol), or by fluvastatin (10 micrograms/ml) respectively. However, unlike LDL derived cholesterol, which also suppresses macrophage LDL receptor activity, lycopene and beta-carotene augmented the activity of the macrophage LDL receptor, similarly to the effect of fluvasfatin. In agreement with these in vitro observations, dietary supplementation of tomato's lycopene (60 mg/day) to 6 males for a 3 months period resulted in a significant 14% reduction in their plasma LDL cholesterol concentrations. We thus conclude that dietary supplementation of carotenoids may act as moderate hypocholesterolemic agents, secondary to their inhibitory effect on macrophage 3-hydroxy-3-methyl glutaryl coenzyme A (HMGCoA) reductase, the rate limiting enzyme in cholesterol synthesis.

Increased uptake of LDL by oxidized macrophages is the result of an initial enhanced LDL receptor activity and of a further progressive oxidation of LDL

Iron ions were recently shown to induce cellular lipid peroxidation in macrophages, and these oxidized cells can convert native low-density lipoprotein (LDL) to oxidized LDL (Ox-LDL). The present study demonstrates that deoxycholic acid (DCA) and angiotensin II (ANG-II) can also induce oxidative modification of macrophages via metal ions independent mechanisms. Furthermore, incubation of LDL (200 micrograms of protein/ml) for 24 h at 37 degrees C with DCA, ANG-II, as well as FeSO4-induced oxidized macrophages, resulted in oxidative modification of the lipoprotein as evidenced by increased TBARS formation in LDL (by 50, 105, and 258%, respectively), decreased TNBS reactivity (by 45, 56, and 42%, respectively), and increased cellular uptake (by 60, 166, and 230%, respectively). A positive correlation (n = .88) was found between the extent of the cellular lipid peroxidation and the increment in the cellular uptake of the LDL. The oxidative modification of LDL by oxidized macrophages was found to be a progressive process. Incubation of LDL with oxidized macrophages for increasing periods of time up to 24 h resulted in progressive increment in: (1) the electrophoretic mobility of the LDL; (2) the TBARS formation in LDL; (3) the cellular uptake of LDL by the oxidized macrophages via the Ox-LDL receptor. Upon fractionation on a heparin-sepharose column of LDL that was incubated for different periods of time with oxidized macrophages, a gradual increment in the unbound LDL fraction was obtained, up to 72% after 24 h of incubation. During the first hour of LDL incubation with the oxidized macrophages a twofold increase in the cellular uptake of LDL by these cells was detected, although no significant oxidation of the lipoprotein occurred during this short time period. This effect could be attributed to an increased number of LDL receptors on the cell surface of the oxidized macrophages. In conclusion, increased uptake of LDL by oxidized macrophages results from two routes: (1) enhanced uptake via the LDL receptor due to increased LDL receptor activity; (2) lipoprotein uptake via the Ox-LDL receptors due to cellular modification of LDL. Both of these processes lead to macrophage cholesterol accumulation and foam cell formation, and thus contribute to accelerated atherosclerosis under oxidative stress.

Effect of deoxycholic acid and ursodeoxycholic acid on lipid peroxidation in cultured macrophages

BACKGROUND

Kupffer cells are essential for normal hepatic homeostasis and when stimulated, they secrete reactive oxygen species, nitric oxide, eicosanoids, and cytokines. Some of these products are cytotoxic and attack nucleic acids, thiol proteins, or membrane lipids causing lipid peroxidation. Hydrophobic bile acids, such as deoxycholic acid (DCA), can damage hepatocytes by solubilising membranes and impairing mitochondrial function, as well as increasing the generation of reactive oxygen species.

OBJECTIVES

The hypothesis that hydrophobic bile acids could stimulate Kupffer cells to increase their capacity to generate reactive oxygen species by measuring cellular lipid peroxidation was tested. Because the hydrophilic bile acid, ursodeoxycholic acid (UDCA) can block hydrophobic bile acid induced cellular phenomena, it was also hypothesised that UDCA could antagonise macrophage activation by hydrophobic bile acids to blunt their capacity to generate reactive oxygen species.

METHODS

J-774A.1 murine macrophages were incubated for 24 hours with either 10(-5) M and 10(-4) M (final concentration) DCA alone, or 10(-4) M UDCA alone, or a mixture of 10(-4) M 1:1 molar ratio of DCA and UDCA. At the end of the incubation period, the culture medium was collected for determination of cellular lipid peroxidation by measuring the malondialdehyde (MDA) content in the medium with the thiobarbituric acid reactive substances assay.

RESULTS

10(-5) M and 10(-4) M DCA increased MDA generation by cultured macrophages. 10(-4) M UDCA alone did not increase MDA generation but blocked the peroxidative actions of DCA.

CONCLUSIONS

Hydrophobic bile acids, after their hepatic retention, can oxidatively activate Kupffer cells to generate reactive oxygen species. Because UDCA can block this action, the beneficial effect of UDCA is, in part, related to its ability to act as an antioxidant.