On supplementing the selenium intake of New Zealanders. 2. Prolonged metabolic experiments with daily supplements of selenomethionine, selenite and fish

1. The daily intake of selenium by three subjects was supplemented with 100 microgram Se as selenomethionine (Semet-Se) or sodium selenite (selenite-Se)/d for 10-11 weeks, or with 65 microgram Se as in mackerel (Scomber japonicus) (fish-Se)/d for 4 weeks. 2. Urinary and faecal excretion of Se was measured and also Se concentration in whole blood, plasma and erythrocytes. Measurements on blood were made at intervals after supplementation had ceased. 3. Selenite-Se was not as well absorbed (0.46 of the intake) during the first 4 weeks as Semet-Se (0.75 of the intake) and fish Se (0.66 of the intake). 4. Blood Se increased steadily with Semet-Se, from 0.08 to 0.18 microgram Se/ml, but more slowly with selenite-Se, reaching a plateau in 7-8 weeks at 0.11 microgram Se/ml. Plasma Se increased more rapidly with Semet-Se than with selenite-Se, so that initially with Semet-Se plasma Se was greater than erythrocyte Se. 5. Daily urinary excretion increased with all forms of supplement, with initially a greater proportion of absorbed selenite-Se being excreted than Semet-Se or fish-Se. A close relationship was found between plasma Se and 24 h urinary excretion. The findings suggested that there was a rapid initial excretion of presumably unbound Se then a slower excretion of residual unbound, loosely bound or bound Se. 6. Total retentions of 3.5 mg selenite-Se and 4.5 mg Semet-Se were large when compared with an estimate of body content of 6 mg Se, derived in another paper (Stewart, Griffiths, Thomson & Robinson, 1978). Retention of Semet-Se and fish-Se appeared to be reflected in blood Se, whereas for selenite-Se, blood Se reflected retention for only a short period after which Se appeared to be retained without altering the blood Se. This suggested that Semet-Se and selenite-Se were metabolized differently. 7. A double blind-dosing trail with 100 microgram Semet-Se was carried out for 12 weeks on twenty-four patients with muscular complaints in Tapanui, a low-Se-soil area. Blood Se increased in the experimental group (from 0.067 to 0.143 microgrm Se/ml); clinical findings were not conclusive and will be presented elsewhere. 8. Bood Se was measured in New Zealand residents before travelling to Europe or to North America. On return their blood Se was increased, and depending upon the period of time spent outside New Zealand some values reached concentrations found in visitors and new settlers to New Zealand. 9. The results from these studies and the earlier studies of single and multiple dosing have been used to look at the various criteria in use for assessing Se status of subjects. It is suggested that plasma Se be used in preference to 24 h urinary excretion, and in addition to whole blood Se and glutathione peroxidase (EC 1.11.1.9) activity.     

On supplementing the selenium intake of New Zealanders. 1. Short experiments with large doses of selenite or selenomethionine

1. Urinary and faecal excretion of single oral doses of 1 mg selenium or 0.1 mg Se as selenomethionine (Semet-Se) in solution were studied in two women. Most of the Se was absorbed and little was eliminated in the urine (0.05-0.22 dose). 2. The results have been compared with those from an earlier study (Thomson, 1974) on the same two women after similarly sized doses of sodium selenite (selenite-Se) in solution. Although selenite-Se was almost as well absorbed as Semet-Se more was excreted in the urine (0.41-0.85 dose). 3. Repeated dosing with 1 mg selenite-Se on five consecutive days in one of the women indicated that 1.1 mg had been retained. 4. Twenty patients with muscular complaints from Tapanui (South Otago, New Zealand), a low-Se soil area, ingested 0.5 mg selenite-Se daily for 20 d. Blood Se increased rapidly to almost twice the initial concentration but reached a plateau well below most values reported for residents outside New Zealand. No difference in blood Se concentration was found between those who did or did not report improvement. 5. Spasmodic medication with selenite-Se by some residents near Lincoln (Christchurch, New Zealand) for periods of up to 10 years or more had increased the blood Se somewhat.     

Effect of chronic selenite supplementation on selenium excretion and organ accumulation in rats

We examined the effect of chronic selenite supplementation on whole body and selected organ selenium (Se) accumulation, urine excretion of total Se and trimethylselenonium ion, and Se balance in adult male rats. Animals were housed in metabolic cages and given either deionized water or water containing 4 micrograms of Se/mL as selenite for 30 d. Absorption of selenite was nearly complete, with only approximately 10% of ingested Se appearing in feces. There was a rapid rise in urinary Se that reached a plateau within a few days and accounted for 54 +/- 2% of the intake. Excretion of trimethylselenonium ion (TMSe) in urine increased rapidly, representing 35-40% of urinary Se in the supplemented animals compared with only 2% for the control group. In one experiment, rats were killed at 30 d and total carcass Se was measured using isotope dilution analysis. Supplemented rats had only a modest increase in whole body Se (94 +/- 4 micrograms Se vs. 66 +/- 3 in controls). Calculation of Se balance in the supplemented rats showed that approximately 35% of ingested Se could not be accounted for by urine plus fecal losses combined with the portion retained in the carcass. The results from this study demonstrate that under the condition of supplementation at 4 micrograms of Se/mL of drinking water, pathways other than urinary and fecal excretion may account for a substantial portion of Se loss.     

Effects of alternate and simultaneous administrations of calcium and phosphorus on calcium metabolism in children receiving total parenteral nutrition

The effects of alternate and simultaneous administrations of calcium (Ca) and phosphorus (P) on Ca metabolism in children receiving total parenteral nutrition (TPN) were examined. Eight children, aged 2 to 36 months, were studied. The following three solutions were administered: solution 1 contains Ca (533 mg/liter); solution 2 contains P (413 mg/liter); and solution 3 contains Ca (267 mg/liter) and P (207 mg/liter). Solutions 1 and 2 were administered alternately for 24-hr periods. (Results) I. During administration of solution 1, significant hypophosphatemia (4.39 +/- 0.26 mg/dl) and hypercalcemia (9.96 +/- 0.15 mg/dl) were observed and, conversely, during administration of solution 2, significant hypocalcemia (8.36 +/- 0.18 mg/dl) and hyperphosphatemia (6.16 +/- 0.27 mg/dl) were observed. During administration of solution 3, the serum levels of both minerals were maintained within the normal ranges (Ca 9.46 +/- 0.12 mg/dl, P 5.65 +/- 0.21 mg/dl). II. The urinary excretion of cyclic AMP was significantly lower during administration of solution 1 (6.67 +/- 0.45 nmol/mg creatinine (Cr] as compared with solution 3 (7.50 +/- 0.61 nmol/mg of Cr). On the other hand, the excretion was significantly higher during administration of solution 2 (11.55 +/- 1.58 nmol/mg of Cr) as compared with solution 3, indicating the existence of secondary hyperparathyroidism. III. The Ca and P retention rates were significantly higher with solution 3 (Ca 79.0 +/- 5.5%, P 73.2 +/- 7.2% of the intake) than with solutions 1 and 2 alternately (Ca 62.7 +/- 4.5%, P 49.2 +/- 9.3%). (Conclusions) Simultaneous administrations of Ca and P are preferable to their alternate administrations for Ca metabolism in children receiving TPN.     

Experimental selenium restriction in healthy adult humans: changes in selenium metabolism studied with stable-isotope methodology

Mechanisms responsible for selenium homeostasis were investigated in healthy adult men receiving diets adequate or low in Se (eight subjects per group). The appearance of a stable isotope of Se, 74Se, in plasma, urine, and feces was measured after oral administration of 74Se-selenite. One group received a restricted level of Se (18 +/- 1 micrograms/d) for 30 d, which resulted in a decrease in urinary, fecal, and plasma Se content compared with the group that consumed 119 +/- 1 micrograms/d. Low Se intake also resulted in decreased urinary 74Se excretion (27.2 +/- 1.4% vs 32.5 +/- 2.3% of the absorbed dose for the adequate intake), increased body retention of 74Se (74.8 +/- 3.1% vs 67.6 +/- 3.8% of the absorbed dose for the adequate group), and a contracted selenite-exchangeable metabolic pool (Se-EMP) (9782 micrograms for adequate Se and 6314 micrograms for the low-Se group; p less than or equal to 0.05). Measurement of Se-EMP may provide an additional and sensitive approach for assessing Se nutriture in human subjects.     

Selenium absorption and retention from a selenite- or selenate-fortified milk-based formula in men measured by a stable-isotope technique

The present study was designed to determine the apparent absorption and retention of the inorganic Se compounds SeO3(2-) and SeO4(2-), which are commonly used for Se fortification of clinical nutrition products and infant formulas. Ten healthy men were fed a milk-based formula labelled with 40 microg Se as 74SeO3(2-) or 76SeO4(2-) on two consecutive days using a randomised crossover design. Se stable-isotope analysis of 9 d complete collections of urine and faeces was used to calculate apparent Se absorption and retention. Se retention from 74SeO3(2-) (41.0 (SD 8.4) %) and from 76SeO4(2-) (46.0 (SD 7.9) %) was not significantly different (P > 0.05). However, Se absorption was significantly higher from SeO4(2-) than from SeO3(2-) (91.3 (SD 1.4) % v. 50.2 (SD 7.8) %, P < 0.05). Urinary excretion of the administered dose was 9.2 (SD 1.8) % for 74SeO3(2-) and 45.3 (SD 8.2) % for 76SeO4(2-) (P < 0.05). Urinary Se excretion kinetics differed significantly for the two Se compounds; 90 % of the total urinary Se was excreted after 121 h for 74SeO32- and after 40 h for 76SeO42- These results suggest that although Se absorption and urinary excretion differ for SeO3(2-) and SeO4(2-), both Se compounds are equally well retained when administered at a relatively low dose (40 microg Se). The nutritional impact of Se fortification of foods would thus be expected to be similar when SeO4(2-) or SeO3(2-) are used.     

The influence of atmospheric chromium on selenium content and glutathione peroxidase activity in blood of tannery workers.

The concentration of selenium and thiobarbituric acid reactive substances (TBARS) and activity of glutathione peroxidase (GSH-Px) were determined in blood of 34 workers of a tannery in Gniezno, Poland, who worked in an area containing chromium compounds. Fourteen workers were exposed to chromium compounds at concentrations of 0.11 +/- 0.07 mg Cr/m3 (mean +/- SD) and 20 at concentrations 5-10 times lower i.e., 0.022 +/- 0.009 mg Cr/m3. Excretion of Se in urine was measured in all of the investigated workers. Decreased Se concentration in whole blood and blood plasma and elevated TBARS concentration in blood plasma were found in the whole group of investigated tanners as compared to controls. Tanners working in areas with high chromium concentrations had a statistically significant decrease in Se concentration in blood and plasma and decreased urinary excretion of the microelement as compared with other tanners. TBARS concentration was 2.5 times lower in workers exposed to higher chromium concentrations (p < 0.005) than in other workers. Positive linear correlations were found between the concentration of Se in blood and the amount of the element excreted in urine (r = 0.48; p < 0.005), the concentration of Se in blood plasma and in urine (r = 0.46; p < 0.01), and the concentration of Se in blood and erythrocyte GSH-Px activity (r = 0.42; p < 0.02). The observed differences between Se concentration in blood and urine of tannery workers and people who are not employed in the industry may indicate a kind of specific adaptation of the body to the working environment containing chromium compounds.     

Pelargonidin is absorbed and metabolized differently than cyanidin after marionberry consumption in pigs

Weaning pigs (7.9 +/- 1.7 kg) were fed a freeze-dried powder of marionberry (MB) by stomach tube to study the absorption and metabolism of anthocyanins. Four major anthocyanins (ACNs) were found in MB: cyanidin-3-glucoside (Cy-3-glc, 78%), cyanidin-3-rutinoside (Cy-3-rutin, 20%), pelargonidin-3-glucoside (Pg-3-glc, 0.4%), and 1 unknown acylated cyanidin-based ACN (UACy, 1.5%). In the urine, the 4 original ACNs and 11 metabolites were identified and quantified. The main metabolites were glucuronidated and/or methylated forms of the original anthocyanins. Total recovery of the 4 original ACNs plus their related metabolites was 0.087 +/- 0.034% for Cy-3-glc, 0.084 +/- 0.026% for Cy-3-rutin, 0.583 +/- 0.229% for Pg-3-glc and 0.036 +/- 0.011% for UACy (mean +/- SD, n = 3), respectively. For the individual ACNs, the amount of metabolites recovered from Cy-3-rutin was lower than that of the original intact Cy-3-rutin, whereas the amounts of metabolites from Cy-3-glc and Pg-3-glc in the urine were much higher than their original forms. In pig plasma, the 2 original ACNs, Cy-3-glc and Cy-3-rutin, and a trace of 1 metabolite (cyanidin monoglucuronide) were detected. The plasma concentration:dose ratio of Cy-3-rutin was higher than that of Cy-3-glc. Different aglycones and/or sugar moieties may influence the absorption and metabolism of ACNs. Cy-3-glc and Cy-3-rutin had similar apparent excretion rates relative to dose, whereas Pg-3-glc had a much higher total urinary excretion than cyanidin-based anthocyanins. Most of Cy-3-glc and Pg-3-glc were excreted in the form of metabolites, whereas most of the Cy-3-rutin was excreted in its original unmetabolized form. Urinary recovery of the acylated anthocyanin was lower than that of nonacylated anthocyanins.     

The effects of different intravenous feeding regimens on the rates of synthesis of alpha1-antitrypsin after surgery

The effects of two nutritional regimens on the synthesis of alpha-1 antitrypsin were investigated postoperatively in gynaecological cancer patients. Total parenteral nutrition (TPN) or a hypocaloric amino acid mixture was administered on the day of surgery and continued for 3 days. The rate of synthesis of alpha-1 antitrypsin was estimated by a computer model from serial plasma concentrations of this protein and a reference protein, albumin. The hypocaloric amino acid mixture resulted in a more negative nitrogen balance than that produced during administration of TPN containing the same amount of nitrogen but more non-protein energy. Urinary excretion of 3-methylhistidine was significantly greater (p = 0.017) in the hypocaloric amino acid group (350 +/- 40 mumol/day; mean +/- SE) on the third postoperative day, as compared to the TPN group (240 +/- 20 mumol/day). In spite of this the synthesis of alpha-1 antitrypsin was apparently greater in the hypocaloric amino acid than in the TPN group. The accumulated plasma appearance rate of alpha-1 antitrypsin was significantly higher (p = 0.0465) in HAA group, at 70 h it was 490 +/- 40 compared to 400 +/- 20 times the pre-operative synthesis in the TPN group.     

Chronic effects of selenite-selenium onDaphnia pulex

Acute and chronic toxicity tests with selenite-selenium (selenite-Se) were conducted onDaphnia pulex. The 48-hr static LC50 was 3.87 mg/L selenite-Se. The sublethal effects of 0.2, 0.4, 0.6, and 0.8 mg/L selenite-Se on the survival, growth, and reproduction ofD. pulex were monitored for 28 days, and the results were analyzed statistically by brood. Appreciable mortality occurred only at 0.8 mg/L Se. Growth, as measured by body length, was depressed at the highest concentration during the preadult instars and was slightly stimulated during the later adult instars. Number of live young per brood was depressed at 0.4, 0.6, and 0.8 mg/L Se during the early broods and apparently was stimulated in later broods. Reproductive dysfunction (i.e., dead young, deteriorated eggs, and abortions) was significant only at higher concentrations in the early broods. Results of the chronic study based on the brood method of analysis indicated safe concentrations between 0.2 and 0.4 mg/L selenite (Se).     

Metabolic studies of [75Se]selenocystine and [75Se]selenomethionine in the rat.

1. The long-term fate in rats of an oral dose of [75Se]selenocystine was compared with that of an oral dose of [75Se]selenomethionine. 2. Urinary and faecal radioactivities were measured during the 1st week and whole-body radioactivity was determined for 10 weeks. Rats were killed at weekly intervals for 4 weeks and at weeks 6 and 10 for analysis of tissue distribution of 75Se. 3. Intestinal absorption of [75Se]selenocystine was 81% of the administered dose; that of [75Se]selenomethionine was 86%. Urinary excretion of absorbed [75Se]selenocystine was 13-9% and that of [75Se]selenomethionine was 5-8% in the 1st week. 4. Whole-body retention of 75Se was greater for [75Se]selenomethionine than for [75Se]selenocystine but after the 1st week it decreased at a similar rate in both groups. Tissue distribution of retained 75Se was also similar in both groups. 5. The initial utilization of [75Se]selenocystine was different from that of [75Se]selenomethionine. However, after the 1st week 75Se from both sources appeared to be metabolized similarly, suggesting that dietary Se of both forms is ultimately incorporated into the same metabolic pool. 6. When these findings were compared with those of earlier studies with [75Se]selenite and 75Se incorporated in vivo into rabbit kidney (RK-64Se) (Thomson, Stewart & Robinson, 1975) the metabolism of [75Se]selenocystine resembled that of [75Se]selenite and RK-75Se, rather than that of [75Se]selenomethionine.     

Platelet glutathione peroxidase activity in long-term total parenteral nutrition with and without selenium supplementation.

Selenium (Se) is not routinely included in total parenteral nutrition (TPN) solution; thus, patients receiving long-term TPN may be at risk of Se deficiency, which may cause fatal cardiomyopathy. Platelet glutathione peroxidase (GSH-Px) activity, as well as Se levels and GSH-Px activity in plasma and erythrocytes during prolonged TPN, was measured in six patients with chronic gastrointestinal disease. During the time course of TPN, Se administration was discontinued for 12 weeks, and then resupplemented for another 12 weeks. Before the study period, all Se indices had been maintained within the normal range. After discontinuation of Se supplementation, a significant decrease in platelet GSH-Px activity was observed after 1 week (from 64 +/- 7 [mean +/- SD] to 39 +/- 5 U/g of protein). After resupplementation, it increased after 1 week (from 44 +/- 9 to 65 +/- 10 U/g of protein). Plasma Se indices significantly changed within 3 weeks after withdrawal and reintroduction of Se (Se: from 136 +/- 28 to 75 +/- 14 and from 61 +/- 22 to 125 +/- 33 micrograms/L; GSH-Px: from 236 +/- 50 to 140 +/- 36 and from 128 +/- 32 to 220 +/- 64 U/L). Erythrocyte Se indices showed no significant changes during the study period. The results demonstrate that platelet GSH-Px activity is the most sensitive index of Se status in TPN patients.     

Short-term dietary selenium restriction in young adults: quantitative studies with the stable isotope 74SeO3(2-)

A 45 d metabolic study was carried out in four young adult male North American residents consuming a controlled diet based on an amino acid mixture. During the initial 10 d, total daily selenium intake was adjusted to 107.7 (SE 0.1) microgram/d, which was reduced to 11.4 (SE 0.1) microgram/d for the remaining 35 d. Two doses of a stable isotope (74SeO3(2-)) were administered orally in the post-absorptive state on days 4 and 39 of the study. Se balance (faecal + urinary excretion) as well as stable isotope excretion studies were carried out for the entire 45 d period; blood plasma and erythrocyte Se concentrations were also monitored. Plasma Se concentrations (microgram/ml) fell progressively from the initial value of 0.132 (SE 0.007) to 0.083 (SE 0.008) at the end of the study. The erythrocyte concentrations of Se did not vary in a consistent manner (average value for the entire study 0.147 (SE 0.002) microgram/ml). Faecal excretion of unenriched Se decreased from 66 (SE 6) microgram/d for days 1-10 to 10.2 (SE 0.8) microgram/d for days 14-40. Mean urinary excretions of the unenriched Se were 43.9 (SE 2.8) microgram/d (days 1-10) and 26.9 (SE 4.6) microgram/d (days 14-40). Total balance (intake-faecal excretion-urinary excretion) for unenriched Se was (microgram/d):-18 (SE 7) days 10-19, -17 (SE 2) days 19-39, -5 (SE 1) days 38-45. Fractional absorption of the ingested label was 0.529 (SE 0.032) and 0.542 (SE 0.038) for the Se-adequate and Se-restricted phases of the study. However, urinary excretion of the absorbed label was reduced from 6.57 (SE 0.73)% for day 1 of the Se-adequate phase to only 3.32 (SE 0.26)% for day 1 of the Se-restricted phase. Similar observations were also made for day 7 of each phase. These findings indicate that immediate contribution of ingested Se to the urinary Se pool is small.     

The retention and distribution by healthy young men of stable isotopes of selenium consumed as selenite, selenate or hydroponically-grown broccoli are dependent on the isotopic form

Twenty-seven healthy young men were randomly assigned to diets that supplied low (32.6 microg/d) or high (226.5 microg/d) levels of selenium for a 105-d study. After consuming the diets for 85 d, subjects were fed a test meal that contained 74Se in the form of selenite or selenate and 82Se incorporated into hydroponically-raised broccoli. Urine, fecal and blood samples were collected daily. Isotope absorption was not different (P > 0.05) for selenate and Se in broccoli; Se absorption from selenite was highly variable and was not included in statistical analyses. Significantly more isotope was absorbed by subjects fed the high Se diet (P = 0. 015). Urinary isotope excretion was greater when selenate was fed than when broccoli was fed (P = 0.0001), and consequently more Se from broccoli (as compared to selenate) was retained (59.2 +/- 2.4 and 36.4 +/- 4.6% for Se in broccoli and selenate, respectively; P = 0.0001). Despite the higher retention, less isotope from broccoli than from selenate was present in the plasma. Plasma proteins separated by gel permeation chromatography showed that most of the isotopes were distributed between two medium molecular weight peaks. Less isotope was found in plasma proteins of subjects fed the high Se diet, but the form of Se had no effect on isotope distribution. These results show that dietary Se intake alters the retention of stable isotopes of Se and that humans retain and distribute Se from broccoli in a different manner than Se from inorganic salts.     

Absorption and metabolism of anthocyanins in elderly women after consumption of elderberry or blueberry

The absorption and metabolism of anthocyanins (ACN) in humans was studied in four elderly women given 12 g elderberry extract (EBX) (720 mg total ACN), and six elderly women given 189 g lowbush blueberry (BB) (690 mg total ACN). The two major ACN in EBX, cyanidin-3-glucoside and cyanidin-3-sambubioside, as well as four metabolites: 1) peonidin 3-glucoside, 2) peonidin 3-sambubioside, 3) peonidin monoglucuronide, and 4) cyanidin-3-glucoside monoglucuronide were identified in urine within 4 h of consumption using HPLC-MS/MS with diode-array detector detection and retention time. Total EBX ACN excretion was 554 +/- 90 microg (mean +/- SD, n = 4) (0.077% of intake/4 h, wt/wt). In 5 of 6 women fed BB, urine samples contained ACN, which were identified as the original forms based upon comparisons to the BB food sample, which contained 24 ACN, 22 of which were identified by HPLC-MS/MS. Reasonable correlations between BB and urine proportions of the different ACN were obtained except for ACN arabinosides. Total urinary excretion during the first 6 h was 23.2 +/- 10.9 microg (mean +/- SD, n = 5) (0.004% of intake/6 h, wt/wt). Plasma ACN levels were below detection limits using 2 mL plasma in women that consumed BB. This study demonstrates for the first time that in vivo methylation of cyanidin to peonidin and glucuronide conjugate formation occurs after people consume ACN and demonstrates the low absorption and excretion of ACN compared with other flavonoids.     

Circulating and excreted levels of chromium after an oral glucose challenge: influence of body mass index, hypoglycemic drugs, and presence and absence of diabetes mellitus

The aim of this study was to observe the effect of obesity on the plasma chromium profile and excretion after a glucose challenge in control subjects and noninsulin-dependent (NIDD) and insulin-dependent diabetics (IDD). All subjects were given 75 g glucose orally; serial blood and urine samples were collected for Cr analysis. Lean control subjects had significantly lower plasma Cr and insulin values than did obese control subjects at all times except zero (1 h, 12.69 +/- 6.73 vs 22.31 +/- 13.27 nmol/L, p less than 0.020). No significant differences were seen between lean and obese NIDDs and IDDs. NIDDs taking drugs had higher Cr values than did lean control subjects (13.08 +/- 0.58 vs 22.31 +/- 5.00 nmol/L, p less than 0.02). Cr concentration of oral drugs was 22.4 ng/tablet and of the soluble insulins was 0.012 +/- .003 ng/U. The lean IDDs excreted higher levels of Cr than did the control subjects; however, Cr excretion within individual groups was not found to be significantly different. The results suggest Cr metabolism is influenced by BMI in control subjects but not in diabetics.     

Plasma vitamin E and selenium and breath pentane in home parenteral nutrition patients

Because both vitamin E and selenium protect against lipid peroxidation, we evaluated the relationship between breath pentane, evolved from the peroxidation of linoleic acid, and plasma levels of alpha-tocopherol (vitamin E), Se, and Se-dependent glutathione peroxidase (Se-GSHPx). Nine home parenteral-nutrition (HPN) patients received added Se in intravenous solutions and were compared with 10 normal control subjects. The excretion of pentane (pmol.kg-1.min-1, means +/- SEM) in control subjects (6.34 +/- 0.96) was significantly lower than in HPN patients (15.02 +/- 1.12, p less than 0.001). alpha-Tocopherol (mumol/L), Se (mumol/L), and Se-GSHPx (U) values were, respectively, 18.13 +/- 1.70, 1.70 +/- 0.05, and 5.34 +/- 0.27 in control subjects and 10.21 +/- 1.66, 1.35 +/- 0.14, and 7.01 +/- 0.31 in HPN patients. All differences were statistically significant. Significant negative correlations were observed between plasma alpha-tocopherol levels and HPN duration and between pentane output and plasma alpha-tocopherol levels (r = -0.58, p less than 0.01). In HPN patients with reduced plasma alpha-tocopherol levels associated with increased pentane output, there is, inferentially, increased lipid peroxidation despite normal plasma Se and Se-GSHPx levels.     

Selenium losses in 10 burned patients

To determine the selenium (Se) losses and balances, 10 patients with burns of 32 +/- 9% (mean +/- SD) of total body surface and aged 36 +/- 9 years were studied from D1 (first post-injury) unitl D7. Cutaneous losses were extracted from the textiles surrounding the patients. Serum and urine were collected until D20. Exudative losses of nitrogen decreased progressively (mean 8.7 +/- 3.8 g/24H). Se was detectable in wound seepage only during excision-grafting: mean operative loss was 342 +/- 191 mug. Mean urinary Se excretion was 41 +/- 13 mug/24H. Operative cutaneous losses led to some negative balances. Serum Se and glutathione peroxydase (GSHPx) were depressed until D20. Serum Se was related to N intake (p < 0.001). The decreased Se and GSHPx levels reflect a deficiency state, which measured losses did not explain, but limitations of the measurement methods prevented detection of Se cutaneous losses 100 mug/24H.     

Phytoremediation management of selenium-laden drainage sediments in the San Luis Drain: a greenhouse feasibility study

An estimated 100,000m(3) selenium (Se)-laden drainage sediment resides in the San Luis Drain (SLD) of Central California. This greenhouse study was undertaken to evaluate the feasibility of growing salt- and boron-tolerant plant species in sediment for reduction of Se content by plant extraction. Drainage sediment was collected from the SLD and mixed with control soil (i.e., uncontaminated soil) to the following ratios (sediment:control soil) by volume: 0:3 (i.e., control soil only), 1:2 (i.e., 1/3 sediment and 2/3 control soil), 2:1 (i.e., 2/3 sediment and 1/3 control soil), and 3:0 (i.e., sediment only). Salt-tolerant plant species consisted of canola (Brassica napus var. Hyola 420), tall fescue (Festuca arundinacea var. Au Triumph), salado grass (Sporobulus airoides), and cordgrass (Spartina patens var. Flageo). Increased ratios of sediment:soil resulted in decreased dry matter production for all tested plant species; especially at ratios of sediment:soil greater than 1:2. Plant Se concentrations (mgkg(-1) DM) ranged as follows for plant species at all ratios of sediment:soil: canola (51-72), tall fescue (16-36), and cordgrass and salado grass (9-14). Total Se concentrations in the soil were at least 20% lower at postharvest compared to preplant concentrations for all plant species at each ratio of sediment:soil. In contrast, water-extractable Se concentrations in the soil were at least three times higher at postharvest than at preplant for all plant species, irrespective of the ratio of sediment:soil. Leaching of Se occurred in irrigated bare pots from each respective ratio of sediment:soil over a duration of 60 days. Based upon the downward movement of Se in bare pots of sediment:soil, it may be more prudent to leave the drainage sediment in the SLD, incorporate clean soil, and then grow low maintenance salt-tolerant plants (e.g., cordgrass, salado grass) in the concrete-lined canal. By this means, possible contamination of groundwater with soluble Se will be eliminated, while phytoremediation slowly reduces Se content in the drainage sediment.     

Digestibility of cocoa butter and corn oil in human subjects: a preliminary study

The comparative absorption of cocoa butter (25.5% C16:0, 34.4% C18:0, 34.4% C18:1, 3.4% C18:2) and corn oil (11.4% C16:0, 2.0% C18:0, 26.4% C18:1, 60.0% C18:2) was assessed in six healthy male subjects. During 3-d experimental diet periods, free-living subjects consumed either cocoa butter or corn oil as virtually the sole source of dietary fat, provided at 40% of the total energy intake in the form of specially formulated cookies. Fat absorption was determined by quantifying total fecal lipid excretion over the 3-d period. Total fecal lipid and fecal fatty acids were determined. The percentage of fat excreted was significantly higher (p less than or equal to 0.001) when subjects consumed the cocoa butter (10.8 +/- 3.2%) vs the corn oil (3.5 +/- 1.0%) diet. These results indicate that the digestibility of cocoa butter is significantly less than corn oil and may explain, in part, previous reports of a neutral effect of dietary cocoa butter on plasma cholesterol concentrations.