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.

Daily selenium intake by breast-fed infants and the selenium concentration in the milk of lactating women in western Poland.

BACKGROUND: Human milk is the only natural source of food for infants during the first several months of life. The milk should contain all trace elements in adequate amounts, including selenium (Se). Se is of particular interest because the daily requirement for this element in infants is higher due to their rapid growth. The aim of our study was to determine the Se concentration in human milk and to calculate the daily Se intake by breast-fed infants in western Poland. MATERIAL AND METHODS: The Se concentration was assayed in mature human milk (14 to 58 days after parturition) collected from 352 lactating women living in 7 voivodeships in western Poland. The concentration of Se was measured by the fluorometric method with 2,3-diaminonaphthalene as a complexing reagent. The values were expressed as ng/ml. RESULTS: No significant differences were observed in terms of Se concentration among the milk samples collected from the different voivodeships. However, the highest values were obtained in the northern part of the region. The mean Se concentration was 10.51 +/- 2.76 ng/ml (range: 10.41-10.65 ng/ml). The calculated mean daily Se intake by breast-fed infants was 7.71 microg/day (range: 3.67-17.17 microg/day). CONCLUSIONS: The Se concentration in human milk in the region studied here is uniform, but the daily Se intake of breast-fed infants in the western part of Poland is lower than the recommended daily requirement. The reason for this situation would appear to be low Se content in the soil, and consequently in the foodstuffs from this region.

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.

Increased plasma glutathione peroxidase activity in patients with acute myocardial infarction.

BACKGROUND: Aim of the study was to determine the concentration of selenium (Se) and the activity of glutathione peroxidase (GSH-Px) in patients with acute myocardial infarction (AMI) and to observe the behavior of these parameters during thrombolysis therapy. MATERIAL AND METHODS: The study comprised two groups of AMI patients and a control group. The first group consisted of 49 patients from whom blood samples were taken after admission to the intensive care unit and subsequently after 3, 7, 14 and 30 days of hospitalization. In the second group of patients (n = 18) blood was taken for measuring only the GSH-Px activity in plasma. In this group blood samples were collected after admission to the hospital, 6, 12, 24, 48 hours, 3, 7, 14 and 30 days later. Control group comprised of 58 healthy subjects. Se levels in whole blood and plasma were measured spectrofluorometrically with 2,3-diaminonaphthalene as a complexing reagent. GSH-Px activity in red cells and plasma was measured spectrofluorometrically with t-butyl hydroperoxide as substrate. RESULTS: In the first group of patients Se concentrations in whole blood and plasma as well as GSH-Px activities in red cells and plasma did not differ significantly from healthy subjects. Both Se levels and GSH-Px activities were stable during the entire period of the study. In the second group of patients, however, plasma GSH-Px activity increased after admission and reached the highest value after 48 hours. This activity was significantly higher compared to healthy subjects (p < 0.004) and to the mean initial activity of this group (p < 0.02). In the later period the activity decreased to the values of healthy subjects. CONCLUSION: We suggest that the increased activity of GSH-Px in plasma of AMI patients is the response of the organism to the increased levels of reactive oxygen species produced during reperfusion and thrombolysis.

Blood selenium and glutathione peroxidases in miscarriage.

OBJECTIVE: To investigate the selenium glutathione and glutathione peroxidase (glutathione-Px) levels in blood in women who experience miscarriage. DESIGN: An observational study. PARTICIPANTS: Forty women with miscarriage occurring in the first and second trimesters. METHODS: Concentrations were measured in whole blood and plasma. Glutathione was measured in red cells and glutathione-Px activity was measured in the red cells and plasma. The results were compared with 36 women in the same period of viable pregnancy and 28 age-matched, healthy, non-pregnant controls. RESULTS: The selenium concentrations in whole blood and plasma of women following abortion were the same as in viable pregnancy, but were significantly lower compared with controls. The glutathione levels were significantly higher in women with miscarriage compared with viable pregnancies and with non-pregnant women. Red cell and plasma glutathione-Px activities of women who had had a miscarriage were significantly lower than in both normal pregnancies and the control group. CONCLUSION: The decreased activities of the antioxidant enzymes, red cell and plasma glutathione-Px, may play an important role in the aetrology of spontaneous abortion.

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 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.

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 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.

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.

Decreased selenium concentration in maternal and cord blood in preterm compared with term delivery.

The Se concentration in maternal and cord whole blood and plasma was determined spectrofluorimetrically in: (1) 42 women at term and (2) 46 at preterm parturients, and in the placenta. The glutathione peroxidase (GSH-Px) activity was measured in red cells and plasma in maternal and cord blood of both groups. The Se concentrations and GSH-Px activities of the above-mentioned groups were compared with those of non-pregnant women. Whole blood and plasma Se concentration of parturients at term did not differ significantly from those of non-pregnant women (72.3 versus 80.3 ng ml-1 whole blood and 48.7 versus 56.2 ng ml-1 plasma). In preterm parturients, however, Se concentrations were significantly lower (61.1 ng ml-1 whole blood and 39.2 ng ml-1 plasma) when compared with term parturients. The Se levels in cord blood and plasma were similar to their mothers' Se concentrations. No difference was observed in placenta Se levels (130 ng g-1 wet weight in both groups). The same was true for glutathione (GSH): the concentration in maternal and cord blood of term and preterm parturients did not differ and varied from 2.43 to 2.50 mmol l-1 red cells. Red cell GSH-Px activities were similar in maternal and cord blood of both term and preterm groups and ranged from 14.3 to 15.7 U g-1 Hb. The plasma enzyme activity in the maternal blood of preterm parturients was significantly (p < 0.05) lower than that of mothers at term delivery. The GSH-Px activity in the plasma of cord blood was significantly (p < 0.001) lower in the preterm than in the term group. It is suggested that low Se levels in the blood of women at preterm delivery, as shown here, may be one of the causes of retinopathy and respiratory distress syndrome in preterm infants.

[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.

Decreased selenium concentration and glutathione peroxidase activity in blood and increase of these parameters in malignant tissue of lung cancer patients.

We studied the selenium (Se) concentration in whole blood and plasma, glutathione peroxidase (GSH-Px) activity in red blood cells and plasma, as well as both of these parameters in cancerous and tumor-free lung tissue of lung cancer patients. Blood samples were taken from 84 cancer patients and 61 healthy controls. Normal and neoplastic lung tissues were obtained from 57 patients at the time of surgery. Se concentrations in whole blood and plasma were lower by 23% (p < 0.001) in patients compared with controls. GSH-Px activity in red cells was lower by 20.2% (p < 0.004) and in plasma by 11.7% (p < 0.05) in patients than in the control group. On the other hand, the tumor Se level was higher by 66.6% (p < 0.0001) and GSH Px activity by 49.5% (p < 0.0001) than in adjacent tumor-free tissue. No differences in Se concentrations and GSH-Px activities were found between squamous cell carcinoma and adenocarcinoma nor among the clinical stages of the disease. In the whole blood and plasma of cancer patients significantly lower Se concentrations were found in smokers than in nonsmokers. Significantly lower Se concentrations were also found among cancer patients who were smokers compared with controls. These findings show that in the blood of cancer the antioxidant ability, as measured by Se and GSH-Px, is reduced significantly. The cause of increased Se and GSH-Px in the malignant part of the lung is not understood and requires further studies.

Selenium supply and glutathione peroxidase activity in breastfed Polish infants.

Selenium (Se) concentration in human milk in Poland is below 10 ng ml-1 and the Se intake by breastfed infants is about 6 micrograms day-1. Supplementation of lactating mothers with selenium-enriched yeast increases rapidly and significantly the Se concentration and glutathione peroxidase activity in maternal blood components. Se concentration in milk is also significantly elevated. After 1 month the mean Se intakes by breastfed infants were greater than the recommended dietary allowance of 10 micrograms day-1 for infants from birth to 6 months of age.

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.

[The role of selenium during pregnancy and in the newborn infant]. / Rola selenu w okresie plodowym i w zyciu niemowlat.

The paper describes the up-to-date knowledge on the essential trace element, selenium, in human nutrition, its concentration in blood during pregnancy and in milk during lactation. Changes in selenium concentration in maternal milk during various stages of lactation and selenium concentration in infant blood as well as the selenium intake by breast- and formula-fed infants is discussed.

[Low levels of selenium and activity of glutathione peroxidase in blood of patients with gastrointestinal neoplasms]. / Male stezenie selenu i aktywnosci peroksydazy glutationowej we krwi chorych na raka przewodu pokarmowego.

Selenium concentrations in the full blood and erythrocyte and plasma GSH-Px activity were determined in patients with cancer of the stomach, colon and rectum. The results were compared with those in the group of healthy subjects. Blood samples were collected into heparinized tubes prior to surgery. Selenium concentrations in the full blood and plasma were lower (75.5 ng/mL and 56.2 ng/ml, respectively) in patients with the cancer of the stomach than healthy subjects (99.5 ng/ml and 78.5 ng/mL, respectively; p < 0.0001). Concentration of this element in both full blood and plasma was also lower in patients with cancer of the colon and rectum (77.7 ng/mL and 61.0 ng/ml, respectively; p < 0.0001). Erythrocyte and plasma GSH-Px activity was also significantly lower (p < 0.001) in patients with cancer of the stomach than in healthy subjects, and amounted to 13.6 U/g Hb and 188 U/L, respectively. Activity of this enzyme in patients with cancer involving lower segment of GI tract amounted to 15.9 U/g Hb and 190 U/L of plasma, and was significantly lower (p < 0.001) than in normal subjects in whom it amounted to 21.0 U/g Hb and 256 U/L of plasma.

Effect of various dietary selenium (Se) intakes on tissue Se levels and glutathione peroxidase activities in lambs.

Experiments were conducted to examine selenium (Se) metabolism in tissues of lambs following Se supplementation at varying doses. For three months four groups of lambs were fed either a basal diet (group A) containing 0.082 mg Se per kg dry matter (ppm) or the same diet plus mineral mixture with Se (as selenite) so that the total diet contained 0.25, 0.41 and 0.58 ppm Se (groups B, C and D, respectively). After three months six lambs of each group were slaughtered and tissues were removed for Se level and GSH-Px activity determinations. Among the tissues of lambs fed the basal diet the highest Se concentration was found in the kidney (1.32 micrograms/g wet weight), and the lowest in the skeletal muscle (0.030 micrograms/g wet weight). In the liver, heart, lung and spleen Se concentrations were almost at the same level and varied in the range of 0.14 to 0.18 micrograms/g wet weight tissue. No increase in Se concentration was found in the kidneys of Se-supplemented animals. Se concentration in the liver and lung increased linearly with the Se level in the diet. In the spleen, heart and skeletal muscle the highest Se concentrations were found in lambs fed 0.41 ppm Se. Tissue GSH-Px activities (calculated on the per g protein basis) increased significantly in Se-treated animals. In the tissues of lambs fed 0.25 ppm Se the enzyme activities were higher in a range of 1.8 to 3.5 as compared to the group fed the basal diet. Higher doses of dietary Se had much smaller effect on the tissues GSH-Px activity.(ABSTRACT TRUNCATED AT 250 WORDS)