The antioxidative role of selenium in pathogenesis of cancer of the female reproductive system.

Selenium, as a component of few antioxidant enzymes, participates indirectly in elimination of reactive oxygen species and in antioxidative defense of the organism. There is a correlation between the concentration of selenium, activity of glutathione peroxidases (GSH-Px), and other parameters of antioxidative defense in blood components. The above mentioned factors were suggested to play an important role in etiopathogenesis of neoplastic diseases. Therefore, the aim of our present study was to compare the selenium status and GSH-Px activity in the plasma of 22 healthy women, 50 individuals suffering from cancer of uterine cervix, uterine corpus or ovary, and 49 women diagnosed with benign neoplasia of the uterine corpus or ovary. In addition, the selenium concentration was measured in postoperative cancer tissues, benign tumors, and histopatologically healthy surgical margins of the aforementioned patients. An average selenium concentration and GSH-Px activity in blood plasma of cancer patients and benign neoplasia patients was significantly lower than in the plasma of healthy women. It suggests that lower overall selenium status and lower selenium-dependent antioxidative capacity of the organism might partly contribute to development of neoplastic diseases of reproductive system. Postoperative tissues of patients revealed significantly higher selenium concentrations in cancer tissues of uterine cervix and corpus, and benign tumors of uterine corpus, as compared to corresponding healthy tissue margins. Higher accumulation of selenium in these neoplastic tissues might reflect a compensatory up-regulation of antioxidant defense systems in tumors that often undergo a persistent oxidative stress.

Blood and tissue selenium concentrations and glutathione peroxidase activities in patients with prostate cancer and benign prostate hyperplasia.

Prostate cancer (PC) is the most common cancer in men and a leading cause of cancer death. Prostatic gland accumulates reasonably high amount of selenium (Se), the element that prevents the development of PC. It is hypothesized that some selenoproteins inhibit the transformation of normal prostate epithelium into neoplasm. We studied Se levels in whole blood, plasma and prostate of 32 PC and 40 benign prostate hyperplasia (BPH) patients and in the control group composed of 39 healthy subjects. The selenoenzyme glutathione peroxidase (GSH-Px) was also measured in the patients' red cells, plasma and prostate tissue. Se concentration in whole blood and plasma in both groups of patients was lower as compared with controls, while in prostate gland it was significantly higher in PC than in BPH patients and controls. Red cell GSH-Px activity was the same in PC patients and controls but significantly lower in BPH patients. Plasma GSH-Px activity was significantly lower in PC patients than in the control group, and prostate GSH-Px activity was significantly lower in PC patients as compared with BPH patients. Since Se has anticancer properties, it is very likely that its low level in blood may facilitate the development of cancer. A higher level of Se in prostate of PC patients has no influence on GSH-Px activity in the gland.

Selenium concentration in the milk of breast-feeding mothers and its geographic distribution.

A total of 905 human milk samples collected in all provinces of Poland, between 12 and 75 days of lactation, were analyzed for selenium concentration. The distribution of Se levels in milk between the provinces was narrow and varied from 8.81 to 11.58 ng/mL, with the mean value (+/- SD) of 10.24 +/- 2.82 ng/mL. The regions with lower levels of Se were in the central and eastern part of Poland; the areas with higher values were in the northern, western, and southern parts of Poland. No significant correlations were found between Se levels in milk and the age of lactating mothers or between Se levels and the postpartum period. The calculated daily Se intakes by breast-fed infants varied from 6.46 to 8.50 microg/day, with the mean value of 7.52 microg/day. This amount does not meet the recommended dietary allowances for infants between 0 and 6 months of age. Based on Se levels in human milk, we present a selenium map of Poland.

Selenium supplementation enhances the element concentration in blood and seminal fluid but does not change the spermatozoal quality characteristics in subfertile men.

The objective of this study was to evaluate the effect of selenium (Se) supplementation on Se concentration and glutathione peroxidase (GSH-Px) activity in blood components and seminal fluid and on spermatozoal quality characteristics in subfertile men. Thirty-three men were supplemented for 12 weeks with 200 micrograms Se/day in the form of yeast-rich Se (group I, n = 16) or sodium selenite (group II, n = 17). Blood samples and sperm were collected at the start of the study and after 2, 4, 8, and 12 weeks following Se supplementation. Se concentration in whole blood and plasma and GSH-Px activity in red cells and plasma increased significantly during the study, but in the group supplemented with yeast-Se the effect was more pronounced. Se concentration in seminal fluid also increased in both groups, but the effect of yeast-Se was markedly higher than that of selenite. In both groups statistically significant correlations were found between Se concentration in plasma and seminal fluid. GSH-Px activity in seminal fluid in the yeast-Se group increased significantly and reached a plateau after 2 weeks, whereas in the selenite group the activity did not change throughout the whole study period. Weak correlations between Se concentrations and GSH-Px activities in seminal fluid were seen, but only in the yeast-Se group were the relations statistically significant. The subjects in both groups showed no response in sperm count, motility, and morphology. In conclusion, we can ascertain that the supplementation of subfertile men with yeast-rich Se showed a more pronounced effect on Se concentrations and GSH-Px activities in blood components and seminal fluid than selenite did. Se supplementation did not improve the spermatozoal quality characteristics of sperm count, motility and, morphology.

Selenium levels in kidney, liver and heart of newborns and infants.

BACKGROUND: Among the tissues of humans the highest level of selenium (Se) is found in the kidney and the lowest in the muscle. The Se level in tissues is age-dependent. AIM: To measure the Se level in kidney, liver and heart of newborns and infants who were born in different periods of pregnancy and died of various diseases. SUBJECTS: Tissues obtained from 49 infants deceased at 1 day to 2.5 months of age. Forty-five of them were premature infants born between 23 and 36 weeks of pregnancy, four were born at term. RESULTS: Se levels in kidney and heart (but not liver) increased gradually with the duration of pregnancy. Positive and significant correlations were found between the weeks of pregnancy and Se levels in kidney (r=0.433, P=0.023) and heart (r=0.313, P=0.030). In the total group, the mean Se levels in the kidney (185+/-64.7 ng/g wet weight) and liver (177+/-59.8 ng/g) were two times higher than those in the heart (90.5+/-33.7 ng/g). In this study, the Se levels in kidney and liver were from 2.5 to 1.2 times lower than the values found in our previous study for healthy adult victims. In the heart, the Se levels were similar in infants and adults. No significant differences were found in the mean Se levels in the various tissues in infants who died due to respiratory distress syndrome, congenital heart disease, other diseases and the group as a whole. The low levels of Se in the tissues studied by us, as compared with data from other countries, are probably due to lower Se intake by pregnant women in Poland. CONCLUSIONS: This study demonstrates that Se level in kidney and heart, but not in liver, increases with the progress of pregnancy. The Se level in kidney and liver is two times higher compared with heart and significantly higher than in adult subjects.

Selenium, glutathione peroxidases, and some other antioxidant parameters in blood of patients with chronic renal failure.

In the present study several parameters associated with oxidative stress were examined in the blood of 25 chronic renal failure (CRF) patients and the results were compared with 18 healthy subjects. Mean creatinine concentration in patients was 1,216 +/- 292 micromol/l. Selenium (Se) concentration in red cells, whole blood and in plasma of CRF patients (106 +/- 32.5, 59.0 +/- 16.7 and 42.4 +/- 13.8 ng/ml, respectively) was significantly (0.0001 < P 0.01) lower (by 20-42%) compared with the controls. Red cell and plasma glutathione peroxidase (GSH-Px) activities (16.6 +/- 3.4 U/g Hb and 93.7 +/- 32.9 U/l plasma) were lower by 12 and 53% (P < 0.05 and < 0.0001, respectively) in patients than in healthy subjects. GSH concentration in red cells of patients (2.81 +/- 0.45 mmol/l) was significantly (P < 0.001) higher (by 20%) than in control group. Malonyldialdehyde (MDA) concentration (expressed as thiobarbituric acid-reactive substances) in red cells of patients (725 +/- 155 nmol/g Hb) was significantly (P < 0.001) higher (by 28%) than in control group. No significant difference was observed in the activity of superoxide dismutase in pLasma between the two groups. In conclusion, our results confirm that the aLterations in Se levels in blood components and in GSH-Px activity in plasma show that the kidney plays an important role in Se homeostasis and in plasma GSH-Px synthesis.

Selenium and glutathione levels, and glutathione peroxidase activities in blood components of uremic patients on hemodialysis supplemented with selenium and treated with erythropoietin.

Patients with chronic renal failure (CRF) often have reduced concentrations of selenium (Se) and lowered activities of glutathione peroxidase (GSH-Px) in blood components. The kidney is a major source of plasma GSH-Px. We measured Se and glutathione levels in blood components and red cell and plasma GSH-Px activities in 58 uremic patients on regular (3 times a week) hemodialysis (HD). The dialyzed patients were divided in 4 subgroups and were supplemented for 3 months with: 1) placebo (bakers yeast), 2) erythropoietin (EPO; 3 times a week with 2,000 U after each HD session), 3) Se-rich yeast (300 microg 3 times a week after each HD), and 4) Se-rich yeast plus EPO in doses as above. The results were compared with those for 25 healthy subjects. The Se concentrations and GSH-Px activities in the blood components of dialyzed uremic patients were significantly lower compared with the control group. Treatment of the HD patients with placebo and EPO only did not change the parameters studied. The treatment with Se as well as with Se and EPO caused an increase in Se levels and red cell GSH-Px activity. Plasma GSH-Px activity, however, increased only slowly or did not change after treatment with Se and with Se plus EPO. In the group treated with Se plus EPO the element concentration in blood components was higher compared with the group supplemented with Se alone. The weak or absence of response in plasma GSH-Px activity to Se supply indicates that the impaired kidney of uremic HD patients has reduced possibilities to synthesize this enzyme.

Organic and inorganic selenium supplementation to lactating mothers increase the blood and milk Se concentrations and Se intake by breast-fed infants.

The aim of this study was to determine the effect of selenium (Se) supplementation to lactating women on Se concentrations and glutathione peroxidase (GSH-Px) activities in blood components of mothers and breast-fed infants and on milk Se levels and Se intake by breast-fed infants. Lactating mothers were supplied for 3 months with 200 micrograms Se/day in the form of yeast-Se (Y-Se) and sodium selenite. Initial blood and plasma Se levels of all women (n = 67) were 76.6 and 53.2 micrograms/L, respectively. After 3 months Se concentrations both in whole blood and in plasma from mothers and infants were significantly higher than the initial values. Y-Se exerts a stronger effects than selenite on blood and plasma Se levels. Initial milk Se concentration was 8.9 micrograms/L and after 1 month in both groups in reached a plateau at 14-16 micrograms/L. This resulted in an increase of Se intake in breast-fed infants from 6.1 to a plateau of 11-13 micrograms Se/day. GSH-Px activities in plasma and red cells of Y-Se group increased significantly and reached a plateau after 1 and 2 months, respectively, while in the selenite group the enzyme activities increased steadily throughout the entire period of the study. Selenite exerts a stronger effect on GSH-Px both in maternal and in infant blood components as compared with Y-Se. In milk the GSH-Px activity in the Y-Se group did not change during the study, while in the selenite group after 3 months it increased almost 2-fold compared to the initial value. In conclusion, this study shows that organic Se causes higher Se deposition than did the inorganic form.

The effect of barium selenate injection on selenium concentration and glutathione peroxidase activity in blood of pregnant ewes fed selenium-deficient diet.

Selenium (Se) levels in whole blood and plasma, and glutathione peroxidase (GSH-Px) activities in red cells and plasma were measured in ewes fed an Se-deficient diet injected with barium selenate before breeding season. Highly significant increases in Se levels and GSH-Px activities (P less than 0.001) were observed throughout the gestation period and during lactation. In the control group, Se levels and GSH-Px activities decreased significantly (P less than 0.001), and were at critically low levels during lambing and lactation periods.

Glutathione peroxidase activity, selenium, and lipid peroxide concentrations in blood from a healthy Polish population : I. Maternal and cord blood.

Selenium (Se) concentrations in whole blood and plasma of 19 nonpregnant women. 14 mothers at delivery, 14 neonates, and 13 infants, aged 2-12 mo, were evaluated. The activity of glutathione peroxidase (GSH-Px) in erythrocytes and plasma and the level of lipid peroxides in plasma were also analyzed. Selenium concentrations in whole blood and plasma in mothers at delivery were significantly lower compared to nonpregnant women. Selenium concentrations in cord blood components were lower compared to mothers, but the differences were not significant. The concentration of the element decreased in the first few months of life. Glutathione peroxidase activity in erythrocytes differed only slightly in the examined groups. In plasma, however, the enzyme activity was significantly lower in pregnant compared to nonpregnant women and in neonates compared to their mothers. Lipid peroxide concentrations in plasma differed only slightly in the examined groups. The results obtained are discussed in terms of the observations of other investigators.

Selenium status, lipid peroxides concentration, and glutathione peroxidase activity in the blood of power station and rubber factory workers.

Concentration of selenium in whole blood and plasma, lipid peroxides in plasma, and glutathione peroxidase activities in red blood cell hemolysates and plasma were determined in 49 coal power plant workers and in 50 rubber factory workers. The results were compared with those obtained for 58 nonindustrial controls. Whole blood selenium was significantly lower and plasma lipid peroxides were significantly higher in power plant workers when compared to the nonindustrial group. In the rubber factory workers, whole blood selenium and red blood cells and plasma glutathione peroxidase activities were significantly lower than in the control group. Urinary output of selenium was also significantly decreased in rubber factory workers. Slightly elevated lipid peroxides were also observed in that group. It seems reasonable to conclude that the lower blood selenium and decreased urinary output of this element may result from increased loss of selenium with perspiration. No correlation has been observed between selenium concentration and glutathione peroxidase activity and between enzyme activity and lipid peroxides concentration in the industrial group.

Tissue level, distribution, and total body selenium content in healthy and diseased humans in Poland.

The authors obtained tissue samples taken at autopsy from 46 healthy individuals killed in accidents and from 75 corpses of victims of various diseases to analyze selenium levels. The per-weight-unit basis of selenium levels (all expressed as ng/gm wet tissue) in tissues decreased in the following order: kidney (469) > liver > spleen > pancreas > heart > brain > lung > bone > skeletal muscle (51). The highest proportion of body selenium was found in skeletal muscles (27.5%); much less selenium was found in bones (16%) and blood (10%). In the tissues of cancer corpses, the selenium levels were much lower than levels in controls. The lowest selenium levels were found in the livers of alcoholics. Tissue selenium levels found in the study were significantly lower than levels reported in Japan, United States, Canada, and other countries. The low selenium levels in the tissues of Polish residents result from inadequate selenium levels in the soil. The authors used selenium levels in tissues to calculate the amount of selenium in humans in Poland (i.e., approximately 5.2 mg). This level was similar to levels found in New Zealand (i.e., 3.0-6.1 mg), but it was lower than the mean level found in Germany (i.e., 6.6 mg) and in the United States (i.e., 13.0-20.3 mg).

[Selenium and some antioxidants in blood of patients with chronic renal failure]. / Selen i niektóre antyoksydanty we krwi chorych na przewlekla niewydolnosc nerek.

Patients with chronic renal failure often have a reduced level of blood selenium. Decreased glutathione level, and the activity of glutathione peroxidase and superoxide dismutase are also lowered. As the effect of these alterations the concentration of malondialdehyde, a marker of the oxidative degradation of polyunsaturated fatty acids, is increased. In patients undergoing regular haemodialysis some of the above mentioned parameters are restored. In dialyzed patients with extremely low concentration of selenium, the administration of this element is recommended.