Selenium status and cardiovascular risk factors in healthy Dutch subjects

To provide further insight into the possible role of selenium in cardiovascular disease, we examined the relationship between cardiovascular risk factors, some nutritional parameters, and short- and long-term selenium status. A total of 82 healthy Dutch volunteers, 59 men and 23 women, aged 40-75 years, were studied. Means and standard deviations of selenium parameters were: plasma selenium 106.4 +/- 23.7 micrograms/L, erythrocyte selenium 0.59 +/- 0.19 microgram/g Hb, toenail selenium 0.78 +/- 0.17 ppm, and erythrocyte glutathione peroxidase activity 28.0 +/- 8.1 U/g Hb. No association was found between selenium status and gender, age, serum total-, LDL-, and HDL-cholesterol, systolic and diastolic blood pressure, alcohol intake, and body mass index. A significantly lower plasma selenium level was observed among smokers compared to nonsmokers (101.0 micrograms/L, SE = 3.9 vs 112.0 micrograms/L, SE = 3.6, p = 0.04). A significant negative association was found between erythrocyte selenium and serum levels of vitamin A and ferritin. No relevant relationship was observed between selenium status and serum fatty acid composition, vitamin E, vitamin B6, and iron. Apart from an association between smoking and short-term selenium status, we found no indications that a possible effect of selenium on cardiovascular disease may operate through the known risk factors.     

Selenium status and cardiovascular risk factors in healthy Dutch subjects.

To provide further insight into the possible role of selenium in cardiovascular disease, we examined the relationship between cardiovascular risk factors, some nutritional parameters, and short- and long-term selenium status. A total of 82 healthy Dutch volunteers, 59 men and 23 women, aged 40-75 years, were studied. Means and standard deviations of selenium parameters were: plasma selenium 106.4 +/? 23.7 micrograms/L, erythrocyte selenium 0.59 +/? 0.19 microgram/g Hb, toenail selenium 0.78 +/? 0.17 ppm, and erythrocyte glutathione peroxidase activity 28.0 +/? 8.1 U/g Hb. No association was found between selenium status and gender, age, serum total-, LDL-, and HDL-cholesterol, systolic and diastolic blood pressure, alcohol intake, and body mass index. A significantly lower plasma selenium level was observed among smokers compared to nonsmokers (101.0 micrograms/L, SE = 3.9 vs 112.0 micrograms/L, SE = 3.6, p = 0.04). A significant negative association was found between erythrocyte selenium and serum levels of vitamin A and ferritin. No relevant relationship was observed between selenium status and serum fatty acid composition, vitamin E, vitamin B6, and iron. Apart from an association between smoking and short-term selenium status, we found no indications that a possible effect of selenium on cardiovascular disease may operate through the known risk factors.     

Selenium in the blood of South Dakotans

Determinations of blood selenium levels of the normal human population in and around the state of South Dakota were made and related to known seleniferous areas. With two exceptions, the highest mean values were obtained in regions where animal selenosis has been observed, but whether any of the samples contained enough selenium to indicate a chronic toxicosis cannot be stated. Data on blood, hair, and urine of four Rapid City residents showed no seasonal differences, and the average blood concentrations were consistent with previous findings. Urine concentrations were variable within limits. Hair was found to be unreliable in evaluating the selenium status of people because of the general use of antidandruff shampoos containing the element.     

Selenium and maternal blood pressure during childbirth

Evidence suggests selenium concentrations outside the nutritional range may worsen cardiovascular health. This paper examines the relationship between selenium and maternal blood pressure (BP) among 270 deliveries using umbilical cord serum as a proxy for maternal exposure levels. Multivariable models used linear splines for selenium and controlled for gestational age, maternal age, race, median household income, parity, smoking, and prepregnancy body mass index. Non-parametric analysis of this dataset was used to select spline knots for selenium at 70 and 90?μg/l. When selenium was <70?μg/l, increasing selenium levels were related to a non-statistically significant decrease in BP. For selenium 70-90?μg/l, a 1?μg/l increase was related to a 0.37?mm?Hg (95% confidence interval (CI): 0.005, 0.73) change in systolic and a 0.35?mm?Hg (0.07, 0.64) change in diastolic BP. There were very few selenium values >90?μg/l. Other studies indicate that the maternal/cord selenium ratio is 1.46 (95% CI: 1.28, 1.65). This u-shaped relationship between selenium and BP is consistent with a dual role of selenium as an essential micronutrient that is nonetheless a toxicant at higher concentrations; however, this needs to be studied further.     

Parvovirus B19 viraemia in Dutch blood donors

Blood, donated by asymptomatic donors, may contain and transmit parvovirus B19. To investigate the dynamics of parvovirus viraemia in asymptomatic blood donors, we studied the amounts of parvovirus DNA in pools of donor plasma, the prevalence of parvovirus antibodies among blood donors in relation to age, and the seasonal and year-to-year variation of the incidence of parvovirus infection in The Netherlands. The incidence of parvovirus infection follows a seasonal cycle and a cycle of several years. Among Dutch blood donors the incidence was estimated to be 0.56% per year. Forty seven out of 100 pools of 5000 plasma donations tested positive for parvovirus DNA. We inferred that the course of viraemia in asymptomatic donors shows a short peak (> 10(9) copies parvovirus DNA/ml), followed by viraemia below 10(6) copies/ml for about 2 weeks.     

Using marine bioassays to classify the toxicity of Dutch harbor sediments

A procedure was developed to assess contaminated marine sediments from Dutch harbors for possible adverse biological effects using three laboratory bioassays: A 10-d survival test with the amphipod Corophium volutator, a 14-d survival test with the heart urchin Echinocardium cordatum (adults), and the bioluminescence inhibition test with the bacterium Vibrio fischeri (Microtox solid phase test LSP]). Microtox results were mathematically corrected for the modifying influence of fine sediment particles. After a validation procedure on test performance and modifying factors, respectively, 81%, 99%, and 90% of the amphipod, heart urchin, and Microtox results were approved. Lower and upper threshold limits for biological effects were set at respectively 24 and 30% mortality for C. volutator, 27 and 35% mortality for E. cordatum, and 24 and 48 toxic units for the Microtox SP based on significant differences with control sediment and the performance of reference sediments. The bioassays clearly distinguished harbor sediments that give rise to acute effects and those that do not. Threshold limits for the amphipods, heart urchins, and bacteria were exceeded in, respectively, 9 to 17%, 33 to 40%, and 23 to 50% of the sediment samples. Highest effects were observed in sediments from the northerly harbors; there was significantly less response in sediments from the Delta Region and the port of Rotterdam (The Netherlands). The procedure outlined in this paper can be used for routine screening of contaminated dredged material that is proposed for open water disposal.     

Dutch dietary guidelines: impact on blood lipids, blood pressure, body composition and urinary mineral excretion of Dutch middle-aged men

In this study the impact of the Dutch dietary guidelines diet on various health status parameters was examined. Twelve apparently healthy men aged 35-52 years were given both the guidelines diet (G) and the 'average' Dutch diet (D) in a controlled eight-week study period with a cross-over design. Compared with the D diet, the G diet contained less fat (accounting for 35 per cent vs 44 per cent of total energy intake), about half the amounts of saturated and monounsaturated fatty acids and twice the amount of polyunsaturated fatty acids. The G diet was given either as a high-sugar or as a low-sugar variant (25 per cent and 15 per cent of total daily energy intake, respectively). Serum total, LDL- and HDL-cholesterol decreased during the four-week G diet from 5.76 to 4.99, from 3.95 to 3.35 and from 1.13 to 1.03 mmol/l respectively. Also the apo-lipoprotein A-I, A-II and B concentrations decreased in subjects on the G diet. Blood pressure and body composition did not change significantly. Urinary pH and the excretion of sodium and potassium were significantly lower for the G diet. It is concluded that the combined factors in the Dutch guidelines diet, irrespective of amount of sugar, has favourable effects on total and LDL-cholesterol levels, whereas the decrease of the concentrations of HDL-cholesterol and of apo-A-I and A-II is less desirable. The changes in urinary mineral excretion, in particular of sodium, during the G-diet is considered as a positive effect.     

Selenium in diet, blood, and toenails in relation to human health in a seleniferous area

To determine whether high dietary selenium intake was associated with adverse effects, selenium in diet, blood, and toenails was studied in relation to human health in adults residing in western South Dakota and eastern Wyoming. Over a 2-y period 142 subjects were recruited from households selected at random and from ranches where unusually high selenium intakes were suspected. Subjects completed health questionnaires, underwent physical examinations, provided blood samples for clinical assessment, and provided blood, urine, toenails, and duplicate-plate food collections for selenium analysis. About half of the 142 free-living subjects had selenium intakes greater than 2.54 mumol/d (200 micrograms/d) (range 0.86-9.20 mumol/d, or 68-724 micrograms/d). Physical findings characteristic of selenium toxicity were not present nor were clinically significant changes in laboratory tests or frequency of symptoms related to selenium in the blood, toenails, or diet. We found no evidence of toxicity from selenium in subjects whose intake was as high as 9.20 mumol/d (724 micrograms/d).     

Selenium contents in blood and urine of persons working with copying machines

Medical investigation was made of 271 workers including 112 males and 159 females exhibited to selenium concentrations lower MAC. The atom absorption spectrometry technique was applied to determine the selenium content levels in blood and urine. The analysis performed revealed increased contents of selenium in the blood of 20.1% and in the urine of 5.5% of those examined. The selenium excretion which followed the use of antidote increased twice. No relationship between the duration of exposition and blood and urine selenium content was revealed. Antidote therapy with CaNa2 EDTA was studied in 16 inpatient clinical cases.     

Selenium levels in human blood and tissues in health and in disease.

The levels of selenium in human sera and pancreatic, hepatic and synovial tissues were measured. An attempt was made to correlate the selenium level with certain disease states. Selenium was determined by nerutron activation analysis, using the 17.4 second half-life isotope 77mSe with a sensitivity of 2ppb. Serum-bound selenium was determined in normal individuals and individuals with various malignancies, and medical and surgical disorders. Tissue selenium was assayed in diseased and normal pancreases, livers, and synovial membranes. A wide variation was observed both in the serum selenium content of patients with a malignancy and in postmoren pancreatic and synovial showing histopathological changes. Significantly lower selenium values were observed in sera from cancer patients than from normal individuals. Higher values were generally observed in patients with primary neoplasms of the reticuloendothelial system. Higher tissue concentrations were obtained in synovia from patients with rheumatoid arthritis and in pancreatic tissues associated with histopathological changes.     

Selenium in eggs and milt of razorback sucker (Xyrauchen texanus) in the middle Green River,Utah

Eggs from three female and milt from five male endangered razorback suckers (Xyrauchen texanus) were collected from the Razorback Bar (about 20 km upstream of Ashley Creek) in the Green River of northeastern Utah. Eggs, but not milt, had concentrations of selenium that were above the range of selenium concentrations in control fish from laboratory studies or reference fish from field studies. The concentrations, however, were below those reported in selenium-exposed fish that had reproductive problems in laboratory studies or field investigations. Tests with three streamside spawned pairs of razorback suckers, which were sampled for eggs and milt in this study, resulted in no hatching of fertilized eggs. Concentrations of selenium in eggs and milt were significantly correlated with selenium concentrations in muscle plugs taken from the same fish, but egg and milt concentrations were not significantly different from muscle plugs. Selenium concentrations in eggs of razorback suckers in the Green River may be sufficiently elevated to cause reproductive problems that are contributing to the decline of this species in the upper Colorado River basin.     

Selenium in diet, blood, and toenails in relation to breast cancer: a case-control study

The association between breast cancer and selenium, measured in the diet, plasma, erythrocytes, and toenails, was investigated in a case-control study in the Netherlands during 1985-1987. Dietary selenium intake was assessed by a structured dietary history technique among 133 breast cancer cases and 238 population controls. Absolute and energy-adjusted selenium intake and selenium concentrations in plasma, erythrocytes, and toenails were similar in cases and controls. The multivariate adjusted odds ratios of breast cancer for subjects in the lowest quartile compared with the highest quartile were 1.6 (95% confidence interval (CI) 0.8-3.4) for dietary selenium, 2.0 (95% CI 0.9-4.4) for plasma selenium, 0.9 (95% CI 0.4-1.9) for erythrocyte selenium, and 1.1 (95% CI 0.6-2.1) for toenail selenium. No statistically significant trend was observed in the odds ratios for any of the four indicators of selenium. These results do not suggest a substantial association between selenium and breast cancer for both short- and long-term markers of selenium status.     

Selenium concentrations in the marine invertebrates Macoma balthica,Mytilus edulis,and Nereis diversicolor

Waders residing in the Dutch Wadden Sea had high selenium concentrations in the tissues. These high concentrations may be a result of a contamination in the food chain, and a selection of marine invertebrate prey animals, the bivalves Macoma balthica and Mytilus edulis and the polychaete Nereis diversicolor, were analyzed for selenium. Selenium concentrations varied by year, season, location, species and size, but the average concentrations (2–6 mg/kg ash free dry weight) remained within the range of known background concentrations in marine invertebrates (1–10 mg/kg DW). However, the highest concentrations approximate the general (sub)toxic level of dietary selenium. The importance of the determination of the selenium compound(s) in marine biota is stressed Macoma had a seasonal variation in selenium concentration that may parallel the reproductive cycle; the highest concentrations (4–5 mg/kg AFDW) were found in the spawning period, the concentration dropped after spawning and in the recovery phase the bivalves were lowest in selenium (2–3 mg/kg AFDW). Intermediate concentrations (3–4 mg/kg AFDW) were measured during the gametogenesis. Concentrations changes in Mytilus corresponded with this pattern.     

Systolic blood pressure and cardiovascular mortality among 13,740 Dutch women

Prospective data of cardiovascular mortality in relation to the systolic blood pressure of women are scarce, especially when combined with other risk factors. The association between systolic blood pressure and cardiovascular mortality was therefore studied in a 10-year follow-up of a population of 13,740 Dutch women, born between 1911 and 1925 who participated in a population-based breast cancer screening project (the DOM Project). Age-adjusted mortality rates over the 10-year follow-up period suggest a J-shaped pattern of cardiovascular mortality according to level of systolic blood pressure. Age-adjusted total cardiovascular, coronary, and cerebrovascular mortality rate ratios were significantly greater than 1.0 among women with elevated systolic blood pressure. Within categories of other risk factors (obesity index, diabetes mellitus, current smoking, and use of antihypertensive medicines) the age-adjusted cardiovascular rate ratios did not show confounding by any of these variables. A very high increase in cardiovascular mortality was observed among hypertensive diabetic women. This study shows that elevated systolic blood pressure is associated with increased rates of cardiovascular mortality for women in this age group.     

Selenium concentration in maternal and umbilical cord blood, placenta and amniotic membranes

The selenium concentration of maternal and umbilical cord whole blood was determined by atomic absorption spectrophotometry in 21 parturients at term. Six placental and amniotic membrane tissue specimens were also investigated. The mean selenium concentrations in the maternal (0.73 +/- 0.15 mumol/l) and umbilical cord blood (0.77 +/- 0.18 mumol/l) were similar and without significant correlation. Placental (2.24 +/- 0.20 mumol/kg wet weight) and amniotic membrane tissue specimens (2.32 +/- 0.54 mumol/kg wet weight) also contained similar concentrations of selenium which were about 3 times higher than those in the maternal and umbilical cord blood. Low whole blood selenium concentration in Finnish parturients may be a sign of deficient nutritional intake of selenium during pregnancy. The relatively high concentration of selenium in the placenta and amniotic membranes on the other hand suggest that metabolically active organs are being provided primarily with this essential trace element.     

Parental solicitation,parental control,child disclosure,and substance use: native and immigrant Dutch adolescents

Objectives. The present study examined whether the relation of parental solicitation, parental control, and child disclosure with adolescent alcohol and cannabis use is similar for native and non-Western immigrant Dutch adolescents.

Design. Questionnaire data from two study-samples were used with a combined sample of 705 adolescents (mean age 16.2 years; 47.2% female; 25.2% non-Western immigrant background).

Results. Native Dutch adolescents reported more weekly alcohol use than immigrant adolescents, while rates of cannabis use by native and immigrant adolescents were similar. Immigrant females reported lower levels of parental solicitation and child disclosure, but higher levels of parental control than native females. There were no differences in the sources of parental knowledge between native and immigrant males. Regression analyses showed no significant interaction effects of parental solicitation, parental control, or child disclosure with ethnic background for both alcohol and cannabis use (all p values?>?.05).

Conclusion. Despite mean level differences in various factors, we did not find evidence of an interaction effect of the sources of parental knowledge with ethnic background on alcohol and cannabis use. This suggests that theories and prevention strategies focusing on these sources of parental knowledge in relation to substance use can be applicable to both native and immigrant Dutch adolescents.     

Effects of no. 2 fuel oil on hatchability of marine and estuarine bird eggs

Summary Eggs of Louisiana herons, sandwich terns, and laughing gulls were oiled with either 0, 5, or 20 l of No. 2 fuel oil in the field and in the laboratory. After 5 days of natural incubation, field-oiled and control eggs were opened and embryonic mortality was determined. No. 2 fuel oil produce'd 61% mortality in Louisiana heron eggs, 56% in sandwich tern eggs, and 83% in laughing gull eggs.Hatching success of artificially incubated, oiled eggs appeared to be lower than in control eggs. However, stress during shipment to the laboratory and problems within the incubator probably contributed to reduced hatchability in both groups.