Toxicity assessment of sediments from three European river basins using a sediment contact test battery.

The toxicity of four polluted sediments and their corresponding reference sediments from three European river basins were investigated using a battery of six sediment contact tests representing three different trophic levels. The tests included were chronic tests with the oligochaete Lumbriculus variegatus, the nematode Caenorhabditis elegans and the mudsnail Potamopyrgus antipodarum, a sub-chronic test with the midge Chironomus riparius, an early life stage test with the zebra fish Danio rerio, and an acute test with the luminescent bacterium Vibrio fischeri. The endpoints, namely survival, growth, reproduction, embryo development and light inhibition, differed between tests. The measured effects were compared to sediment contamination translated into toxic units (TU) on the basis of acute toxicity to Daphnia magna and Pimephales promelas, and multi-substance Potentially Affected Fractions of species (msPAF) as an estimate for expected community effects. The test battery could clearly detect toxicity of the polluted sediments with test-specific responses to the different sediments. The msPAF and TU-based toxicity estimations confirmed the results of the biotests by predicting a higher toxic risk for the polluted sediments compared to the corresponding reference sediments, but partly having a different emphasis from the biotests. The results demonstrate differences in the sensitivities of species and emphasize the need for data on multiple species, when estimating the effects of sediment pollution on the benthic community.

Arsenic in drinking water wells on the Bolivian high plain: Field monitoring and effect of salinity on removal efficiency of iron-oxides-containing filters.

In the rural areas around Oruro (Bolivia), untreated groundwater is used directly as drinking water. This research aimed to evaluate the general drinking water quality, with focus on arsenic (As) concentrations, based on analysis of 67 samples from about 16 communities of the Oruro district. Subsequently a filter using Iron Oxide Coated Sand (IOCS) and a filter using a Composite Iron Matrix (CIM) were tested for their arsenic removal capacity using synthetic water mimicking real groundwater. Heavy metal concentrations in the sampled drinking water barely exceeded WHO guidelines. Arsenic concentrations reached values up to 964 µ g L⁻¹ and exceeded the current WHO provisional guideline value of 10 µ g L⁻¹ in more than 50% of the sampled wells. The WHO guideline of 250 mg L⁻¹ for chloride and sulphate was also exceeded in more than a third of the samples, indicating high salinity in the drinking waters. Synthetic drinking water could be treated effectively by the IOCS- and CIM-based filters reducing As to concentrations lower than 10 µ g L⁻¹. High levels of chloride and sulphate did not influence As removal efficiency. However, phosphate concentrations in the range from 4 to 24 mg L⁻¹ drastically decreased removal efficiency of the IOCS-based filter but had no effects on removal efficiency of the CIM-based filter. Results of this study can be used as a base for further testing and practical implementation of drinking water purification in the Oruro region.

Influence of tidal regime on the distribution of trace metals in a contaminated tidal freshwater marsh soil colonized with common reed (Phragmites australis).

A historical input of trace metals into tidal marshes fringing the river Scheldt may be a cause for concern. Nevertheless, the specific physicochemical form, rather than the total concentration, determines the ecotoxicological risk of metals in the soil. In this study the effect of tidal regime on the distribution of trace metals in different compartments of the soil was investigated. As, Cd, Cu and Zn concentrations in sediment, pore water and in roots were determined along a depth profile. Total sediment metal concentrations were similar at different sites, reflecting pollution history. Pore water metal concentrations were generally higher under less flooded conditions (mean is (2.32+/-0.08)x10(-3) mg Cd L(-1) and (1.53+/-0.03) x 10(-3) mg Cd L(-1)). Metal concentrations associated with roots (mean is 202.47+/-2.83 mg Cd kg(-1) and 69.39+/-0.99 mg Cd kg(-1)) were up to 10 times higher than sediment (mean is 20.48+/-0.19 mg Cd kg(-1) and 20.42+/-0.21 mg Cd kg(-1)) metal concentrations and higher under dryer conditions. Despite high metal concentrations associated with roots, the major part of the metals in the marsh soil is still associated with the sediment as the overall biomass of roots is small compared to the sediment.

Effect of fortified spread on homocysteine concentration in apparently healthy volunteers.

OBJECTIVE: To determine the effect of folic acid, vitamin B(6) and B(12) fortified spreads on the blood concentrations of these vitamins and homocysteine. DESIGN AND SETTING: A 6-week randomized, double-blinded, placebo-controlled, parallel trial carried out in a clinical research center. SUBJECTS: One hundred and fifty healthy volunteers (50% males). INTERVENTIONS: For 6 weeks, the subjects consumed the test spreads (20 g/day): containing per 20 g (1) 200 microg folic acid, 2 microg vitamin B(12) and 1 mg vitamin B(6), or (2) 400 microg folic acid, 2 microg vitamin B(12) and 1 mg vitamin B(6) or (3) no B-vitamins (control spread). RESULTS: The B-vitamin status increased on using the test spreads, with the largest effect on the serum folate concentration: 48% in men and 58% in women on spread 1 and 92 and 146%, respectively, on spread 2 (P-values all <0.05). The plasma homocysteine decreased in the groups treated with the fortified spreads as compared to the control group. Average decreases were for males: 0.7+/-1.5 micromol/l (6.8%) on spread 1 and 1.7+/-1.7 micromol/l (17.6%) on spread 2 and for females: 1.4+/-1.2 micromol/l (14.2%) and 2.4+/-2.0 micromol/l (23.3%), respectively (P-values all <0.05). CONCLUSIONS: Consumption of a spread fortified with folic acid, vitamin B(6) and vitamin B(12) for 6 weeks significantly increases the blood concentrations of these vitamins and significantly decreases the plasma concentration of homocysteine. Fortified staple foods like spreads can contribute to the lowering of homocysteine concentrations.

Conjugated linoleic acid isomers have differential effects on triglyceride secretion in Hep G2 cells.

The effect of different conjugated linoleic acid (CLA) isomers (trans-10,cis-12 (t10,c12)-CLA and cis-9,trans-11 (c9,t11)-CLA), compared with oleic acid (OA) and linoleic acid (LA), on hepatic lipid synthesis and secretion were investigated in Hep G2 cells. The cells were incubated in a medium containing 1 mmol/l fatty acid-bovine serum albumin (BSA) complex for 5 h, with BSA alone as control. [(3)H]Glycerol and [(14)C]acetate were used to monitor lipid synthesis and secretion. The results show that cellular uptake rates of these fatty acids were similar. Incubation with OA, t10,c12-CLA, c9,t11-CLA and LA resulted in 6-, 4-, 2- and 1.8-fold increases in intracellular [(3)H]triglyceride ([(3)H]TG) compared with incubation with BSA alone. OA, LA and c9,t11-CLA increased [(3)H]TG secretion 3.6-, 2.5- and 1.2-fold above the control, whereas t10,c12-CLA markedly suppressed the secretion of [(3)H]TG. Hepatic secretion of TG mass increased 3.5-, 3.3-, 2.7- and 1.5-fold in the cells incubated with OA, LA, c9,t11-CLA and t10,c12-CLA, respectively. Since the secreted TG is mainly contained in very low density lipoproteins (VLDL), the decreased ([(3)H])TG secretion by t10,c12-CLA reflects a diminished secretion of VLDL. With respect to cholesterol synthesis OA was more effective in stimulating the incorporation of [(14)C]acetate into cellular total cholesterol followed in descending order by LA, c9,t11-CLA and t10,c12-CLA. In conclusion, the biological properties of 18-carbon fatty acids are clearly influenced by both the number and (geometric) positions of their double bonds. Furthermore t10,c12-CLA is more effective than c9,t11-CLA on suppressing hepatic TG secretion in vitro.

Effects of prostaglandins on coronary flow rate and left ventricular work in isolated rat heart.

In isolated rat hearts PGD2, PGE1, PGE2, PGF2 alpha and PGI2 increased coronary flow rate at concentrations of about 23, 1.4, 0.4, 2.5 and 0.6 nmol per l respectively. PGD2, PGE2, and PGI2 did not affect left ventricular work (W 1v). PGE1 (14 nmol/l) lowered W 1v (12% and PGF2 alpha (9 nmol/l) increased W 1v (10%). It is concluded that endogenously released PGI2 can probably affect coronary flow rate.

Possible beneficial effect of fish and fish n-3 polyunsaturated fatty acids in breast and colorectal cancer.

Breast and colorectal cancer are main causes of death in industrialized countries. In these cancers dietary factors appear to play beneficial or adverse roles. One of the possible beneficial factors may be fish intake or the n-3 polyunsaturated fatty acids from fish, as found in epidemiological and clinical studies. In population studies, high intake of fish during many years is associated with reduced risks of breast and colorectal cancer. Prospective and case-control studies either do not show an association between fish intake and cancer risks or show reduced risks at high fish intakes. In these studies, fish consumption may have been too low or may not reflect fish consumption over a longer period. In population, case-control, and prospective studies, fish and fish n-3 polyunsaturated fatty acids were not found to increase cancer risks. Clinical studies on markers of colorectal cancer indicate that fish n-3 polyunsaturated fatty acids may reduce cancer risk. In several studies in which the effect of fish consumption on cancer risk was investigated, meat and meat products were positively related to cancer risk, suggesting that cancer risks might be reduced more effectively when meat and meat products in meals are replaced by fish. In conclusion, the existing knowledge suggests that an increase in the consumption of fish and fish n-3 polyunsaturated fatty acids in industrialized countries may contribute to lower breast and colorectal cancer risks.

Influences of dietary fats on coronary flow rate and left ventricular work of the isolated rat heart: sunflower seed oil versus lard.

The influences of dietary sunflower seed oil and lard on coronary flow rate and external left ventricular work were studied in the isolated Langendorff-perfused and working rat heart. For 1, 4 or 6 weeks, rats were fed diets containing 25--50% of the total digestible energy as fat, 23% as casein an 52--27% as starch. The coronary flow rate and the maximum left ventricular work of hearts of rats fed sunflower seed oil were higher than those of hearts of rats fed lard (about 15 and 10%, respectively). The maximum left ventricular work was achieved at a left ventricular filling pressure of 10--12 mm Hg: this value was not affected by the type of dietary fat. The effect of dietary fat on coronary flow rare is already seen after 1 week of feeding, and on left ventricular work after 4 weeks of feeding. Analysis of variance shows a positive relationship between the maximum left ventricular work and the amount of sunflower seed oil. It is concluded that dietary fats affect coronary flow rate and left ventricular work in the isolated rat heart. The increase in left ventricular work may be caused by an increase in contractility.

Effects of dietary fats on the coronary flow rate and the left ventricular function of the isolated rat heart.

Two groups of rats were fed diets containing large amounts (45-50% of the total digestible energy) of sunflower seed oil or hydrogenated coconut oil for 4-5 days. The left ventricular working capacity, the coronary flow rate, the oxygen consumption, the glucose uptake and the lactate release were determined in the isolated perfused heart. The fatty acid composition of the heart phospholipids was also determined. The left ventricular working capacity and the coronary flow rate of hearts of rats fed sunflower seed oil are higher (10-20%) than those of rats fed hydrogenated coconut oil. Feeding the two fats for 3-4 weeks instead of 4-5 days does not alter the results. There are no or only minor differences between the two dietary groups as to the other quantities mentioned. It is concluded that dietary fats affect the properties of the heart already after a short feeding time.

Health aspects of fish and n-3 polyunsaturated fatty acids from plant and marine origin.

An expert workshop reviewed the health effects of n-3 polyunsaturated fatty acids (PUFA), and came to the following conclusions. 1. Consumption of fish may reduce the risk of coronary heart disease (CHD). People at risk for CHD are therefore advised to eat fish once a week. The n-3 PUFA in fish are probably the active agents. People who do not eat fish should consider obtaining 200 mg of very long chain n-3 PUFA daily from other sources. 2. Marine n-3 PUFA somewhat alleviate the symptoms of rheumatoid arthritis. 3. There is incomplete but growing evidence that consumption of the plant n-3 PUFA, alpha-linolenic acid, reduces the risk of CHD. An intake of 2 g/d or 1% of energy of alpha-linolenic acid appears prudent. 4. The ratio of total n-3 over n-6 PUFA (linoleic acid) is not useful for characterising foods or diets because plant and marine n-3 PUFA show different effects, and because a decrease in n-6 PUFA intake does not produce the same effects as an increase in n-3 PUFA intake. Separate recommendations for alpha-linolenic acid, marine n-3 PUFA and linoleic acid are preferred.

Acute absorption of folic acid from a fortified low-fat spread.

OBJECTIVE: To explore the feasibility of low-fat spreads as vehicles for folic acid (FA) fortification by determining the acute absorption of FA from a fortified spread. DESIGN: Double blind, crossover study to test each of the following treatments administered at 1-weekly intervals: (A) 20 g low-fat (40%) spread fortified with 200 microg FA and a placebo tablet; (B) 20 g low-fat placebo spread and a 200 microg FA tablet; (C) 20 g low-fat placebo spread and a placebo tablet. SUBJECTS: A total of 13 male volunteers, aged 31.8+/-13.2 y. MAIN OUTCOME MEASURES: Plasma total folate concentrations, measured before and up to 10 h after each treatment (n=10 samples per treatment). RESULTS: Plasma folate concentrations were significantly increased compared with baseline values 1 h after administration of the FA tablet, and 1.5 h after the FA spread, and remained significantly higher than the baseline values for up to 7 h after both treatments. The maximum plasma folate response (R(max)), corrected for baseline values and 'placebo response', was established between 1 and 3 h postprandially in response to both FA spread and FA tablet, and no significant difference in R(max) was found between the two treatments (13.4 vs 14.4 nmol/l, P=0.9). The acute absorption of FA from fortified spread relative to that from the tablet, calculated on the basis of area under the plasma folate response curve, was 67% (P=0.04). CONCLUSION: The absorption of FA from fortified low-fat spread, although lower than from a tablet, is effective. These results suggest that low-fat spreads, typically associated with fat-soluble vitamin fortification, may also be considered feasible as vehicles for FA fortification.

Assessing the impact of chemical pollution on benthic invertebrates from three different European rivers using a weight-of-evidence approach.

The aim of this study was to combine different lines of evidence on the impact of chemical pollution on benthic invertebrate communities in three European river basins (Elbe, Scheldt, and Llobregat). The study integrates chemical analyses, a battery of different sediment toxicity tests, and field data from soft-sediment meio- and macrobenthic fauna within a sediment-quality triad in which chironomids, oligochaetes, and nematodes are identified on the species level. The use of TU (toxic units) and msPAF (multi-substance potentially affected fraction) in an approach assessing the chemical impact as well as the integration of sediment toxicity tests with bacteria (Vibrio fischeri), benthic invertebrates (Caenorhabditis elegans, Potamopyrgus antipodarum, Lumbriculus variegatus, Chironomus riparius), and fish embryos (Danio rerio), together with univariate and non-parametric multivariate statistical analyses of the biological data revealed significant differences between unpolluted and polluted sites in all three river basins. To combine the different results obtained in the sediment-quality triad, a scoring system was successfully developed based on a simple algorithm. This system provides an easily understandable scheme for non-experts among decision makers and water managers.

PGF2 alpha stimulates release of PGE2 and PGI2 in the isolated perfused rat heart.

The effect of prostaglandin F2 alpha on the release of PGI2 and PGE2 was investigated in isolated perfused rat heart. PGF2 alpha at concentrations of 1.7 nmoles liter-1 or higher increased the release of PGI2 and PGE2 alpha. The release of PGI2 was highest after 3 to 4 min of perfusion with PGF2 alpha. This phenomenon may be of physiological significance and might explain the observed variable effects of PGF2 alpha on vascular resistance.

A modified Langendorff technique for metabolic investigations.

A small amount of fluid keeps dripping from the apex of the isolated, perfused heart, after cannulating the pulmonary artery and carefully preventing leakage from caval and pulmonary veins. This fluid has a high absorbance at 280 nm, which points to a high protein content; it shows a fall in glucose, and a rise in lactate concentration almost corresponding with the heart's total glucose uptake and lactate release respectively. The data suggest that a small amount of the perfusion fluid reaches the surface of the heart via the interstitial space.

Influences of dietary fats on the coronary flow and oxygen consumption of the isolated rat heart.

The influence of various diets on the coronary flow (Qcor) and oxygen consumption (VO2m) of Langendorff-perfused rat hearts was studied. The diets contained 23 percent of the total amount of calories as proteins and sufficient amounts of minerals and vitamins, while the amounts of starch and type of fat were varied. In the Langendorff set-up, the perfusion pressure (Pp), and/or the developed left ventricular pressure (PD) were varied to change Qcor and VO2m. At Pp = 50 and 90 mm Hg, Qcor and VO2m of the isolated hearts of rats fed 50 percent of the total number of calories (cal%) as sunflower seed oil (50 SSO) or 50 cal% palm oil (50 PO) for 3 days were 10--20 percent higher than those of the hearts of rats fed pellets (11 cal% fat). At Pp = 80 mm Hg and at various levels of PD, Qcor of the isolated hearts of rats fed 50 SSO or 45 PO + 5 SSO for 3 months was about 20 percent higher than that of the isolated hearts of rats fed a high carbohydrate diet. No differences were found in VO2m or in the maximum obtainable value of PD. When rats were fed mixtures (total amount of fat 50 cal%) of SSO and hardened coconut oil (CO) for 3 days, Qcor increased with increasing dietary SSO. The value of Qcor of the isolated hearts of rats fed a high carbohydrate diet containing 5 cal% SSO was in between the values of the groups fed 50 SSO and 45 CO + 5 SSO. Perfusion of the latter two groups of hearts with substrate-free medium increased Qcor by about 35 percent. The total hypoxanthine + inosine output in these two groups of hearts was about 4.0 nmoles-min-1, and remained contstant during perfusion with substrate-free medium. We conclude that the composition of the diet influences the coronary flow of isolated perfused rat hearts. The amount and the type of dietary fat influence both the magnitude and the direction of the effects. The relationship between the type of dietary fat and its effects on coronary flow is complex.

Both raw and retrograded starch decrease serum triacylglycerol concentration and fat accretion in the rat.

Male Wistar rats were meal-fed on diets containing various amounts of resistant starch in the form of raw starch (either amylomaize starch, potato starch or modified high-amylose starch) or retrograded starch (prepared from each of the starches) for 6 weeks. Two diets containing normal maize starch were fed as diets poor in resistant starch. Energy absorption (energy consumption minus faecal energy loss), growth, weight of the epididymal fat pads, serum total cholesterol and triacylglycerol concentrations and a number of intestinal and faecal variables were determined. The resistant starches affected all the variables determined except the serum total cholesterol concentration. Relationships were found between energy absorption and both growth and the weight of the fat pads, and between the weight of the fat pads and both the serum triacylglycerol concentration and the serum total cholesterol concentration. No clear differences between the effects of the two types of resistant starch (raw starch v. retrograded starch) were found except that raw potato starch hardly stimulated H2 excretion and led to lower amounts of propionic and butyric acids in the caecal contents than the other starches. The results suggest that dietary resistant starch reduces energy absorption leading to less abdominal depot fat and lower serum triacylglycerol concentrations.