Serum selenium concentrations in ovarian cancer patients using a simplified fluorimetric procedure

An Assessment of Serum Selenium Concentration in Women with Ovarian Cancer

BACKGROUND

Available studies on the effect of serum selenium levels on the risk of malignancies show some conflicting results. In this study, we investigated the correlation between serum selenium levels and ovarian cancer occurrence.

METHODS

314 women (157 diseased patients and 157 healthy ones) matched in terms of age and BMI were included in the study. The measurements of selenium in the collected blood samples were performed using an ICP mass spectrometer. Univariable and multivariable analyzes were performed to determine the relationship between the factors under the study and the occurrence of ovarian cancer.

RESULTS

The mean concentration of selenium was lower among diseased ones than among controls (53.31 μg/L vs. 78.99 μg/L). A decrease in selenium concentration was noticed with the advancement of ovarian cancer. In univariable and multivariable analyzes, a clear relationship between low selenium concentration and the occurrence of ovarian cancer was found (35.3 (95% CI: 11.2-111; p < 0.001) and 45.8 (95% CI: 12.8-164; p < 0.001)).

CONCLUSION

The studied patients with ovarian cancer are characterized by statistically significant lower serum selenium levels than patients from the control group. Among the study group, a decrease in selenium concentration was observed with an increase in the FIGO stage. The determination of the role of selenium as a prophylactic factor in ovarian cancer requires further prospective studies.

Evaluation of trace elements associated with antioxidant enzymes in blood of primary epithelial ovarian cancer patients

Epithelial ovarian cancer (EOC) has been associated with oxidative stress (OS) due to epithelial inflammation which makes ovaries more vulnerable to the deleterious effects of reactive oxygen species (ROS). However, antioxidant enzymes (AOEs) such as manganese-superoxide dismutase (Mn-SOD), copper,zinc-superoxide dismutase (Cu,Zn-SOD) and glutathione peroxidase (GPx1) protect cells against the biological damage of ROS-induced OS and support cancer prevention by maintaining normal cell cycle progression, inhibiting proliferation, tumor invasion, angiogenesis, inflammation or inducing apoptosis. In the present study, we aimed to measure the levels of trace elements [manganese (Mn), copper (Cu), zinc (Zn) and selenium (Se)] which are structurally and/or functionally associated with the AOEs by inductively coupled plasma/mass-spectrometry (ICP/MS) in blood samples of patients with EOC (M, n = 26) and compare the data with healthy subjects (C, n = 46). Serous EOC (M1, n = 18) data were also evaluated according to the tumor grading [well or moderately well differentiated (G 1-2) vs. poorly differentiated or undifferentiated (G3)] and staging of disease [stage I-II (SI-II) vs. stage III (SIII)]. We obtained; i) The Mn and Se levels of M were significantly lower than C, ii) only Mn levels were changed [(G3_(Mn) < G 1-2 _(Mn)] in M1, iii) significant correlations were observed between [Cu and Zn levels (r = 0.701, p = 0.036) in G 1-2 and (r = 0.686, p = 0.041) in G3; Cu and Se levels (r = 0.960, p = 0.000) in G3; Mn levels and Mn-SOD expression (r = 0.551, p = 0.006) in M, (r = 0.857, p = 0.007) in G 1-2 and (r = 0.690, p = 0.056) in G3; Se levels and erythrocyte GPx1 activity (r = 0.660, p = 0.053) in G 1-2 ; Se levels and erythrocyte Cu,Zn-SOD activity (r = 0.693, p = 0.038) in G3]. The study revealed that trace elements, particularly low Mn and Se levels along with high Cu/Se ratios might be of value in all histologic subtypes of EOC. Although Mn level was important in terms of discriminating tumor grades, positive correlation between Cu-Se levels was also remarkable in patients with G 1-2 tumors of M1. Moreover, high erythrocyte Cu/Se ratios might be a favourable marker for EOC.

Total and individual antioxidant intake and risk of epithelial ovarian cancer

BACKGROUND

Limiting oxidative stress to the ovarian epithelium has been proposed as a first-line defense against ovarian cancer. Although evidence for an association between individual dietary antioxidant intake and ovarian cancer risk is conflicting, the combined evidence suggests a modest inverse association. Our study aimed to evaluate the association between total antioxidant capacity (TAC) and individual antioxidant intakes (vitamin C, vitamin E, beta-carotene, selenium, lutein, and lycopene) and ovarian cancer risk.

METHODS

We conducted a population-based case-control study in New Jersey. Cases were women ages 21 years and older with newly diagnosed epithelial ovarian cancer who resided in six counties of New Jersey. Controls were women in the same age range who resided in the same geographic area. A total of 205 ovarian cancer cases and 390 controls were included. Dietary intake was ascertained using the Block food frequency questionnaire (FFQ), and TAC indices were constructed by linking FFQ-derived estimates to two standardized antioxidant capacity databases, the USDA Oxygen Radical Absorbance Capacity (ORAC) Database, and the University of Olso's Antioxidant Food Database. Multivariate logistic regression models were used to calculate odds ratios and 95 % confidence intervals while controlling for major ovarian cancer risk factors.

RESULTS

We found a strong inverse association with selenium from food sources (OR: 0.41; 95 % CI: 0.20-0.85, for the highest vs. lowest tertile of dietary selenium intake). However, there was little evidence of an association with dietary TAC or the others individual antioxidants. In contrast, compared to non-users, supplement users had significant increased risk for all micronutrients, but no statistically significant increased risk was observed for combined intake from foods and supplements of any of these antioxidants.

CONCLUSIONS

This study found an inverse association between selenium consumption from food sources and ovarian cancer risk, while there was little evidence of an association with TAC or any of the other individual antioxidants. Additional research is needed to confirm these findings.

Indirect spectrophotometric determination of small amounts of selenium(IV) and arsenic(V) by simple extraction using flotation columns

A simple, rapid and selective procedure for the indirect spectrophotometric determination of Se(IV) and As(V) has been developed. It is based on the reduction of Se(IV) to Se(0) and As(V) to As(III) with hydroiodic acid (KI + HCl). The liberated iodine, equivalent to each analyte, is quantitatively extracted with oleic acid (HOL) surfactant. The iodine-HOL system exhibits its maximum absorbance at 435 nm. The different analytical parameters affecting the extraction and determination processes have been examined. The calibration graphs were found to be linear over the ranges 5-120 and 0.25-20 ppm of Se(IV) and As(V), with lower detection limits of 2.5 and 0.15 ppm and molar absorptivities of 1 x 10(4) and 0.5 x 10(4) dm3 mol(-1) cm(-1), respectively. Sandell's sensitivity was calculated to be 0.0078 and 0.0149 microg/cm2 in the same order. The relative standard deviation for five replicate analyses of 40 ppm Se(IV) and 4 ppm As(V) were 1.0 and 0.9%, respectively. The proposed procedure in the presence of EDTA as a masking agent for foreign ions has been successfully applied to the determination of Se(IV) in a reference sample and As(V) in copper metal, in addition to their determination in spiked and polluted water samples.

Gastric tissue selenium levels in healthy persons, cancer and non-cancer patients with different kinds of mucosal damage

The gastric tissue levels of selenium (Se) were examined in 15 healthy subjects aged 18-43 (mean 36 +/- 12) years, 17 patients with stomach cancer aged 23-79 (mean 60 +/- 17) years, 20 patients with mild gastritis aged 18-65 (mean 35 +/- 12) years, 13 patients with chronic gastritis aged 28-69 (mean 47 +/- 15) years, 33 patients with erosive gastritis aged 16-70 (mean 49 +/- 17) years and 23 patients with ulcers aged 22-76 (mean 49 +/- 17) years. The Se concentration was determined by electrothermal atomic absorption spectrometry (ETAAS) with palladium as a matrix modifier. The mean +/- the standard deviation (SD) of the gastric tissue Se levels were 473 +/- 80, 36 +/- 9.0, 355 +/- 243, 567 +/- 246, 571 +/- 241 and 813 +/- 427 micrograms/Kg in healthy subjects and in patients with cancer, ulcers, mild gastritis, chronic gastritis and erosive gastritis, respectively. The Se concentration in the biopsies of patients with gastric ulceration and cancer were significantly lower than that in patients with gastritis (p < 0.05) and the other conditions (p < 0.0001).

Determination of selenium in blood components by X-ray emission spectrometry. Procedures, concentration levels, and health implications

Sampling, storing, sample pretreatment, and experimental conditions for selenium (Se) determination in human serum, plasma, and whole blood by X-ray emission spectrometric (XRS) methods are described. Concentration levels in these biological fluids, found by this technique, are discussed and compared to values found by other techniques for the same healthy population group in the same area. XRS analysis of blood from patients with various pathological conditions is reviewed, with special attention to the relation of Se with the concentration level of other essential or nonessential trace elements.

Chemoprevention of cancer: selenium

1. Selenium intake (in the form of selenite, selenate, selenomethionine, etc.) protects the organism against the action of some kinds of carcinogens. 2. People and animals having less Se in their blood are at a higher risk of acquiring cancer than those whose blood contains more of this element. 3. This chemopreventive action is probably due to antioxidant properties of Se, its involvements in the enzyme glutathione peroxidase as well as in the inhibition of enzymes converting carcinogens to their ultimate forms in the cell. 4. An intake of 150-300 micrograms of Se daily is considered to be adequate to protect the human organism without exhibiting the toxic properties of this element.