Effect of acute selenium restriction on whole body endogenous selenium and the selenite-exchangeable metabolic pool in the adult rat

The time course of changes in whole body endogenous selenium (Se(end)) was investigated during a short-term (7-day) selenium restriction study in the adult rat. The method of continuous feeding with a stable isotope of selenium was used to permit normal intake of selenium while distinguishing between the dietary and endogenous components of body selenium. Additionally, the effect of short-term selenium restriction on the time course of the selenite-exchangeable metabolic pool (Se-EMP) was investigated. Two groups of adult male rats were intubated with the in vivo stable isotope (74)SeO(3)(2-), then fed a Torula yeast diet (selenium <0.02 microg/g) and either deionized water (-Se group) or deionized water containing selenium as (76)SeO(3)(2-) (0.1 microg selenium/ml) (+Se group). Three animals from each group were killed at 24-hour intervals. Whole body Se(end) and the estimated size of Se-EMP (W(Se-EMP)) were determined using hydride generation-inductively coupled plasma mass spectrometry for isotopic measurements. Whole body Se(end) decreased linearly in the +Se group (Se degrees (end): 54.4 microg; Se(end) at 3 days: 49.3 +/- 2.1; Se(end) at 7 days: 45.2 +/- 2.2). The decrease was exponential for the -Se group (Se degrees (end): 54.4 microg; Se(end) at 3 days: 42.9 +/- 0.3; Se(end) at 7 days: 42.2 +/- 0.7). The value of W(Se-EMP,pl) (microg) was 19.8 +/- 0.6 at 1 day and 19.7 +/- 1.0 at 7 days for the +Se group. The corresponding values for the -Se group were 15.7 +/- 1.5 and 18.8 +/- 0.4. All respective values of W(Se-EMP,pl) for the -Se group were significantly smaller than for the +Se group (P < 0.05), with the exception of values at days 6 and 7. The value of W(Se-EMP,urine) (microg) was 2.1 +/- 0.2 at 1 day, increasing rapidly to 23.5 +/- 1.5 at 7 days for the +Se group. The corresponding values for the -Se group were 3.0 and 23.1.     

Effect of dietary selenium restriction on selected parameters of selenium status in men with high life-long intake

The influence of selenium (Se) restriction on disposition in plasma and urine fractions of infused (74)Se (selenite) was studied when adult males (Enshi City, Hubei Province, PRC) whose habitual daily Se intake is approximately 480 microg per day were transferred to Lichuan County, where the daily intake is approximately 30 microg. The subjects received an infusion (106 microg Se) on the day before consuming foods low in Se and a second infusion (113 microg Se) 63 days later. Blood and 24-hour urine samples were collected each day for 7 days after the first infusion and on days 22, 43, and 62 following the first infusion. Urine and blood were also collected daily for the next 7 days after the second infusion. Plasma total Se concentration increased for 7 days after each of the two infusions and urine Se decreased exponentially following both the first and second infusions. The excretion of trimethylselenonium followed the same pattern as the total urinary Se. Surprisingly, there was not a significant difference in selenite retention between the two infusion periods, and the data indicated that, regardless of the chemical form of Se present in various organs, its catabolism leading to excretion in urine followed the same pathway as that of selenite. Labeled Se was incorporated predominantly in the plasma selenoprotein P fraction and the half-life of Se in this fraction was determined to be 1.9 to 2.9 days. Thus, a longer depletion period is required in these subjects to obtain more significant changes.     

Decrease of erythropoietin level by human recombinant tumour necrosis factor alpha (hrec TNFalpha) in patients with advanced cancer

Anaemia is a frequent complication of chronic inflammation, infectious diseases and cancer. Inappropriate erythropoietin production is regarded as one of the main causative factors responsible for the occurrence of anaemia. The pathogenesis of TNFalpha induced-anaemia has not been fully clarified yet and its influence on hematopoiesis has been suggested. We performed a clinical study to access the influence of hrec TNFalpha administration on plasma EPO concentration and the degree of anaemia in patients with advanced solid tumours for whom no other kind of therapy but palliative treatment was available. All these patients exposed mild anaemia (HT 36.1 +/- 1.0%). Plasma EPO was estimated at 8 a.m. before and after 5 days of TNFalpha therapy with a dose of 75 pg/day iv (cycle I). Two weeks later plasma EPO was estimated again before and after 5 days of TNFalpha administration of a double dose (150 microg/day) (cycle II). The control group comprised 8 non-cancer patients (5M/3F, age 48.5 +/- 6yr) with the same degree of anaemia (HT 36 +/- 1.1%) due to haemorrhage. In the control group the plasma EPO level was significantly higher (54.2 +/- 8 mU/ml) than in cancer patients before cycle I (17.1 +/- 2.5 mU/ml) and II (14.6 +/- 3.8 mU/ml) respectively.TNF administration was followed by a significant decline of plasma EPO both after the first (17.1 +/- 2.5 vs 9.0 +/- 1.5 mU/ml) and second cycle (14.6 +/- 3.8 vs 8.4 +/- 2.0 mU/ml) of TNF treatment. CONCLUSIONS: Patients with solid cancer and mild anaemia are characterised by inappropriate low plasma EPO concentration. Therapy with TNFalpha exerts a suppressive effect on EPO secretion in these patients.     

Investigation of the pharmacokinetics of gemcitabine and 2',2'-difluorodeoxyuridine in human plasma by liquid chromatography

Gemcitabine (2',2'-difluorodeoxycytidine, dFdC) is a difluorine-substituted deoxycytidine analogue that has demonstrated antitumor activity against solid tumors. The pharmacokinetics of dFdC and its metabolite, 2',2'-difluorodeoxyuridine (dFdU) have been studied; however, their disposition has never been evaluated in a patient with bladder cancer. A patient with bladder cancer was treated with dFdC 1000 mg/m(2) over a 30min period. The patient received a dFdC infusion once per week for 3 weeks followed by a rest week. Serial plasma samples were obtained prior to, during, and after completion of the infusion for determination of dFdC and dFdU concentrations. dFdC and dFdU concentrations were measured using normal-phase high-performance liquid chromatography and one-compartment open model methods. Maximum plasma concentrations (C(max)) and area under the plasma concentration-time curve for dFdC and dFdU were 24.5 microg/ml and 11200 microg/Lh, 49.1 microg/ml and 272,800 microg/Lh, respectively.     

A report of high-dose selenium supplementation: response and toxicities.

Concerns about the toxicity of selenium has limited the doses used in chemoprevention. Based on previous studies, intakes of 400 microg/day and plasma selenium of 1000 ng/ml (Dietary Reference Intakes, Academy Press, New York, 2000, p. 384) were established as the no observed adverse effect level (NOAEL). This investigation summarizes the plasma response and toxicity reports from 24 men with biopsy-proven prostate cancer who were randomized to either 1600 or 3200 microg/day of selenized yeast as part of a controlled clinical trial testing selenium as a chemopreventive agent for prostate cancer progression. Subjects were on these doses for averages of almost 12 months. Plasma selenium levels were monitored throughout the course of follow-up. Symptoms of selenium toxicity were assessed by patient interview with specific questions regarding breath, hair and nail changes. Several liver and kidney function tests and hematology were measured at 6-month intervals. 8 subjects were randomized to the 1600 microg/day and 16 to the 3200 microg/day group. The mean plasma selenium levels achieved with supplementation were 492.2 ng/ml (SD = 188.3) and 639.7 ng/ml (SD = 490.7) for the 1600 and 3200 microg/ day doses, respectively. The 3200 microg/day group reported more selenium-related side effects. Blood chemistry and hematology results were all within normal limits for both treatment groups. More subjects on 3200 microg/day reported symptoms of selenium toxicity; however, these reports did not correspond to peaks in plasma selenium levels. We observed no obvious selenium-related serious toxicities. As selenium is used in more chemoprevention and therapeutic settings, additional information on selenium species, sequestration of selenium in specific organs, excretion, and toxicities is needed.     

Iodine and zinc, but not selenium and copper, deficiency exists in a male Turkish population with endemic goiter

Although endemic goiter has been shown to have a high prevalence in Turkey, little is known about the concentration of urinary iodine, plasma selenium (Se), copper (Cu), and zinc (Zn) in these patients. We studied on 140 male patient with endemic goiter (mean age: 22.2 ± 0.19 yr) and 140 healthy male subjects (mean age: 21.8 ± 0.28 yr). Daily urinary iodine excretion was determined by the ionometric method. Plasma Se, Zn, and Cu were determined by using atomic absorption spectrometry. Daily urinary iodine excretion was found to be significantly lower in the patient group (38.7 ± 2.26 μg/d) than that of controls (50.73 ± 2.56 μg/day,p = 0.001). Plasma Zn concentrations were also found to be significantly lower in the patient group (1.04 ± 0.03 μg/mL) than that of controls (1.16 ± 0.02 μg/mL,p = 0.001). No significant difference was determined in Se and Cu concentrations between the patient and control groups. Our study shows that a moderate iodine deficiency exists in both patients with endemic goiter and control subjects, which indicates the important role of iodine deficiency in the etiopathogenesis of endemic goiter in Turkey. Zinc deficiency may also contribute to the pathogenesis of endemic goiter. However, Se and Cu do not seem to have any role in the etiopathogenesis of endemic goiter in Turkey. A community-based iodine fortification program throughout the country may be proposed to take over the problem, which also can prevent the contributing effects of other element deficiencies that occur when iodine deficiency is the prevailing factor.     

Bioavailability of selenium from meat and broccoli as determined by retention and distribution of 75Se

The concentration of selenium (Se), an essential nutrient, is variable in foods, depending, in part, on how and where foods are produced; some foods accumulate substantial amounts of Se when produced on high-Se soils. The chemical form of Se also differs among foods. Broccoli is a Se-accumulating plant that contains many methylated forms of Se, and Se bioavailability from broccoli has been reported to be low. Red meats such as pork or beef could accumulate Se when the animal is fed high-Se diets, and Se from such meats has been reported to be highly bioavailable for selenoprotein synthesis. In a further attempt to characterize the utilization of Se from broccoli and meats such as pork or beef, we have fed rats diets adequate (0.1 μg Se/g diet) in Se or high in Se (1.5 μg S/g diet), with the Se source being either high-Se broccoli or beef. Rats were then given test meals of broccoli or pork intrinsically labeled with ⁷⁵Se. When dietary Se was nutritionally adequate (0.1 μg/g diet), more ⁷⁵Se from pork than broccoli was retained in tissues; however, there were no significant differences in whole-body retention when dietary Se was high (1.5 μg/g diet). A significantly greater percentage of ⁷⁵Se from broccoli than pork was excreted in the urine and dietary Se did not affect urinary excretion of broccoli ⁷⁵Se, but the amount excreted from pork varied directly with dietary Se intake. Radiolabeled ⁷⁵Se derived from pork effectively labeled selenoproteins in all tissues examined, but ⁷⁵Se from broccoli was undetectable in selenoproteins. These differences in retention and distribution of Se from broccoli or pork are consistent with reported differences in bioavailability of Se from beef and broccoli. They also suggest that there are fewer differences in bioavailability when Se is consumed in supranutritional amounts.     

Selenium status of the Australian population: effect of age, gender and cardiovascular disease

Selenium (Se) is an essential trace element and the clinical consequences of Se deficiency have been well-documented. Se is primarily obtained through the diet and recent studies have suggested that the level of Se in Australian foods is declining. Currently there is limited data on the Se status of the Australian population so the aim of this study was to determine the plasma concentration of Se and glutathione peroxidase (GSH-Px), a well-established biomarker of Se status. Furthermore, the effect of gender, age and presence of cardiovascular disease (CVD) was also examined. Blood plasma samples from healthy subjects (140 samples, mean age = 54 years; range, 20-86 years) and CVD patients (112 samples, mean age = 67 years; range, 40-87 years) were analysed for Se concentration and GSH-Px activity. The results revealed that the healthy Australian cohort had a mean plasma Se level of 100.2 +/- 1.3 microg Se/L and a mean GSH-Px activity of 108.8 +/- 1.7 U/L. Although the mean value for plasma Se reached the level required for optimal GSH-Px activity (i.e. 100 microg Se/L), 47% of the healthy individuals tested fell below this level. Further evaluation revealed that certain age groups were more at risk of a lowered Se status, in particular, the oldest age group of over 81 years (females = 97.6 +/- 6.1 microg Se/L; males = 89.4 +/- 3.8 microg Se/L). The difference in Se status between males and females was not found to be significant. The presence of CVD did not appear to influence Se status, with the exception of the over 81 age group, which showed a trend for a further decline in Se status with disease (plasma Se, 93.5 +/- 3.6 microg Se/L for healthy versus 88.2 +/- 5.3 microg Se/L for CVD; plasma GSH-Px, 98.3 +/- 3.9 U/L for healthy versus 87.0 +/- 6.5 U/L for CVD). These findings emphasise the importance of an adequate dietary intake of Se for the maintenance of a healthy ageing population, especially in terms of cardiovascular health.     

A comparison of leptin and ghrelin levels in plasma and saliva of young healthy subjects

In the last 10 years, saliva has been increasingly used as a diagnostic fluid and in predictions of disease progression. Leptin and ghrelin are synthesized in several tissues including the salivary glands. The action of ghrelin is antagonistic to that of leptin. This study was undertaken to measure and compare the saliva ghrelin-leptin and plasma ghrelin-leptin levels in healthy young subjects. In 30 healthy subjects, after an overnight fast, saliva and plasma leptin levels were measured using the ELISA method while saliva and plasma immunoreactive ghrelin levels were measured using a commercial radioimmunoassay (RIA). The latter uses 125I-labeled bioactive ghrelin as a tracer and a rabbit polyclonal antibody raised against full-length octanoylated human ghrelin (Phoenix, Europe, Karlsruhe, Germany). The results of this investigation revealed that saliva leptin levels (6.19+/-2.10 microg/l) were lower than plasma levels (7.39+/-3.23 microg/l) while saliva ghrelin levels (188.5+/-84.7 pg/ml) were higher than plasma levels (126.4+/-38.5 pg/ml), when male and female subjects were considered together. Saliva leptin levels (5.93+/-1.94 microg/l) were lower than plasma levels (6.22+/-2.92 pg/ml) while saliva ghrelin levels (190.3+/-80.2 pg/ml) were higher than plasma levels (120.4+/-35.7 pg/ml) in young males. Saliva leptin levels (6.47+/-2.29 microg/l) were lower than plasma levels (8.73+/-3.14 microg/l) while saliva ghrelin levels (183.2+/-90.2 pg/ml) were higher than plasma levels (129.3+/-42.8 pg/ml) in young females, and both saliva and plasma leptin levels were slightly lower in male subjects in comparison with female subjects. Also, Immunohistochemistry study indicated that ghrelin positivity was found in ductus epithelium of salivary gland. We have demonstrated for the first time that saliva ghrelin levels were higher than in plasma while saliva leptin levels were almost the same as in plasma. Measurements of ghrelin and leptin in saliva is non-invasive, simple, and generally much preferred by patients and thus may be an acceptable alternative to plasma sampling.     

Blood Selenium in Naturally Fed Horses and the Effect of Selenium Administration

Blood Se of adult horses was 26.1, 25.8, and 27.0 ng/ml (mean values at 3 farms), where the Se of food was about 20 ng/g dry substance. Experimental adult horses which received about 41 ng Se/g food showed 45.3 ng/ml blood. At low Se intake suckling foals show higher blood Se than mares, but with high Se intake, the opposite will occur. This is reflected in milk Se, which raises but slowly with rise of mare’s blood Se. Se in blood plasma and in blood corpuscles is on the same level. The effect of various dose levels of Se on blood Se was studied: From 1.5 to 6 mg Se/week, blood Se rose rather linearity; 18 and 30 rag Se/week gave but slightly more effect than 6 mg.     

Acetone extract of Bupleurum scorzonerifolium inhibits proliferation of A549 human lung cancer cells via inducing apoptosis and suppressing telomerase activity

Bupleuri radix, a traditional Chinese herb, has been widely used to treat liver diseases such as hepatitis and cirrhosis. The acetone extract of Bupleurum scorzonerifolium (AE-BS) showed a dose-dependently antiproliferative effect on the proliferation of A549 human lung cancer cells. The IC(50) of AE-BS, i.e., the concentration required to inhibit proliferation of A549 cells, was 59 +/- 4.5 microg/ml on day 1. The IC(50) of AE-BS for WI38 human normal lung fibroblast cells, however, was significant higher than that for A549 cells (150 +/- 16 microg/ml, p< 0.01). After 72 hours of exposure, AE-BS (60 microg/ml) significantly reduced A549 cell proliferation to 33 +/- 3.2% of control. In TUNEL assay, A549 cells treated with AE-BS showed typical morphologic features of apoptosis, and the percentage of apoptotic cells was approximately 38 % on day 1. In the TRAP assay, AE-BS-treated cells demonstrated significantly lower telomerase activity on day 3. This result indicates that the AE-BS could suppress the proliferation of lung cancer cells via inhibition of telomerase activity and activation of apoptosis.     

Ion-pair reversed-phase HPLC: assay validation of sodium tanshinone IIA sulfonate in mouse plasma

Sodium tanshinone IIA sulfonate (STS), a hydrophilic ionic substance, is used as a cardiovascular drug. An ion-pair reversed-phase high-performance liquid chromatography (IP-RP-HPLC) method for the determination of STS in mouse plasma was initially developed. The assay involved a rapid and simple extraction process and subsequent detection at 271 nm. The retention time for STS was 7.5 min. Based on extracted STS standard mouse plasma at 1.5,10 and 50 microg/ml, the assay precision were 2.7, 2.1 and 1.7% with a mean accuracy of 96.7, 98.5 and 99.4%, respectively. At plasma concentration of 1.5, 50 and 75 microg/ml, the mean recovery of STS were 93.1, 96.3 and 97.5%. The limit of detection (LOD) and limit of quantification (LOQ) for STS was 0.1 microg/ml and 0.5 microg/ml, respectively. Linear responses were observed over a wide concentration range (0.5-100 microg/ml) for STS in mouse plasma. STS can be detected after intravenous administration. This method was performed for the first time in pharmacokinetic studies of STS in the mouse.     

Dietary intake of arsenic, mercury and selenium by children from a German North Sea island using duplicate portion sampling

The dietary intake of arsenic, selenium and mercury was studied for children living on the North Sea island Amrum, Germany. Altogether, 98 duplicate portions were collected from 14 children (age 1.5-5.5 years) in April and May 1995 over a sampling period of 7 days, respectively. The element concentrations in duplicate samples were measured by atomic absorption spectrometry. The weekly As and Hg intake (median and range) was 2.31 and 0.89-6.75 microg/(kg(bw) x week) for As and 0.13 and 0.060-0.62 microg/(kg(bw) x week) for Hg. Compared with the provisional tolerable weekly intake (PTWI) for As and Hg as proposed by the WHO, German children from coastal areas reveal no health risks due to As and Hg dietary intake. The daily Se intake (median and range) was 19 and 6-160 microg/day. The appropriate Se intake of 10-40 microg/day, as recommended by the Austrian, German, and Swiss Nutrition Councils for 1-4 years-old children, was not reached in 8 out of 49 cases (16.3%), whereas the recommended Se intake, fixed at 15-45 microg/day for the 4-7 years-old children, was not reached in 15 out of 48 cases (31.3%).     

Rapid determination of the synthetic pyrethroid insecticide, deltamethrin, in rat plasma and tissues by HPLC

Deltamethrin (DLM), [(S)-alpha-cyano-d-phenoxybenzyl-(1R,3R)-e-(2,2 dibromovinyl)-2,2-dimethylcyclo-propane-1-carboxylate], is a pyrethroid insecticide widely used in agriculture and households. There are several methods for analysis of DLM in biological fluids and tissues, but these methods are time consuming. They generally involve the extraction of DLM with lipid-soluble solvents such as n-pentane, n-hexane, diethylether or acetone, and subsequent evaporation of the solvent. A more rapid and sensitive high-performance liquid chromatography (HPLC) method to analyze DLM in plasma and tissues (liver, kidney, and brain) was developed and validated according to U.S. Food and Drug Administration (U.S. FDA) and International Conference on Harmonization (ICH) of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines. The limit of detection (S/N of 3/1) for DLM was 0.01 microg/ml for plasma, liver, kidney and brain. The method performances were shown to be selective for DLM and linear over the concentration range 0.01-20.0 microg/ml. For five replications of samples at 0.05, 0.1, 0.2, 1.5 and 4.0 microg/ml, intraday precision and accuracy values were in the range of 0.7-13.1% relative standard deviation (%R.S.D.) and 1.8-14.1%Error, respectively. Interday (n = 15) precision and accuracy values at 0.05, 0.1, 0.2, 1.5, and 4.0 microg/ml were in the range of 3.2-15.2% (%R.S.D.) and 3.7-14.8%Error, respectively. The absolute recoveries of DLM ranged from 93 to 103% for plasma, 95 to 114% for liver, 97 to 108% for kidney, and 95 to 108% for brain. This method can be quite useful for DLM pharmacokinetic and tissue distribution studies, for which multiple plasma and tissue samples have to be analyzed quickly with high reproducibility.     

Selenium Content in Blood Fractions and Liver of Beef Heifers Is Greater with a Mix of Inorganic/Organic or Organic Versus Inorganic Supplemental Selenium but the Time Required for Maximal Assimilation Is Tissue-Specific

Selenium (Se) content of feedstuffs is dependent on the Se level of the soil. Even though Se in grass and forage crops is primarily present in organic forms, Se is commonly supplemented in cattle diets in an inorganic (sodium selenite) form in geographic regions where Se soil concentrations are low. The purpose of this study was to answer two important questions about inorganic (ISe) vs organic (OSe) forms of dietary supplementation of Se (3?mg/day) to growing beef heifers (0.5?kg/day): (1) what would the effect of supplementing Se with an equal blend of ISe:OSe (Mix) have on Se tissue concentrations and (2) how long does it take for the greater assimilation with OSE to occur and stabilize? A long-term (224?day) Se dietary supplementation trial was conducted with serial sampling performed (days?28, 56, 112, and 224) to determine the length of time required to achieve Se supplement (OSE, Mix, and ISe)-dependent changes in Se assimilation in blood fractions and liver tissue. Forty maturing Angus heifers were fed a corn silage-based diet for 98?days with no Se supplementation, and then a cracked corn/cottonseed hull-based diet (basal diet) without Se supplementation for 74?days. Liver biopsies were taken for Se analysis, and heifers were fed the same diet for another 14?days. Heifers were assigned (n?=?10) to one of four Se treatment groups such that basal liver Se contents were stratified among groups, and then fed enough of the basal diet (0.08?mg Se per day) and a mineral-vitamin mix that provided 0.16 (control) or 3.0?mg Se per day in ISe (sodium selenite), OSe (Sel-Plex(?)), or Mix (1:1 ISe:OSe) form to support 0.5?kg/day growth for 224?days. More Se was found in whole blood, red blood cells, serum, and liver of Mix and OSe heifers than ISe heifers, and all were greater than control. Se content either increased until day?56 then was stable (liver and plasma), or was stable until day?56 (whole blood) or day?112 (red blood cells) and then increased steadily through day?224, for all supplemental Se treatments. These data indicate that a 1:1 mix (1.5?mg Se:1.5?mg Se) of supplemental ISe and OSe is equal to 3?mg/day OSe supplementation and greater than 3?mg/day ISe supplementation. The data also indicate that Se levels stabilized in liver and plasma by 56 to 112?days whereas whole blood and red blood cell concentrations were still increasing through 224?days of supplementation, regardless of the form of supplemental Se.     

Bioavailability and possible benefits of wheat intake naturally enriched with selenium and its products

Bioavailability and possible benefits of wheat intake naturally enriched with selenium and its products was tested. Wheat obtained by application of an original combination and procedure for foliar supplementation of plants with Se was characterized on the average by five times higher content of Se, the main form being l-(+)-selenomethionine (SeMet). Substitution of Se-deficient wheat by wheat naturally enriched with Se and its products contributed to the increase of daily intake on the average by 18 μg (12–35 μg) in volunteers, which is more than 50% of the average daily intake. Six weeks after the beginning of its application, increased daily intake of Se brought about the increase of its concentration in the plasma of the examined persons by 53%, in their erythrocytes by 37%, in their hair by 44%, and in their urine by 54%. This result was comparable to the effect obtained in the course of an 8-wk daily intake of supplements with 100 μg Se in the form of enriched bakery yeast. Analysis of glutathione peroxidase (GSH-Px) activity in blood, thiobarbituric acid reactive substances (TBARS) in plasma, lipid parameters (total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides), and glucose in serum of volunteers showed that the increased Se intake induced increased GSH-Px activity in blood and decreased concentrations of TBARS, lipid parameters, and glucose in blood. Using only one crop (wheat enriched with Se), the existing deficiency of Se in our population can be alleviated. In this way, one-fourth of our population with lower Se intake than 21 μg/d will satisfy basal requirements, whereas one-half will become moderately deficient in Se instead of distinctly deficient in Se.     

Increased cytotoxicity of soluble Fas ligand by fusing isoleucine zipper motif

Fas (CD95) ligand (FasL) has the ability to induce apoptosis in Fas-expressing glioma cells by binding to Fas. Several molecular species have been designed to be soluble Fas ligands for therapeutic purposes. We successfully constructed a chimeric soluble FasL by fusing an isoleucine zipper motif for self-oligomerization and a FLAG sequence to the extracellular domain of the human Fas ligand (FIZ-shFasL). The cytotoxic effect of FIZ-shFasL on Jurkat cells was equivalent to that of membrane-bound FasL and approximately 10-fold stronger than that of agonistic anti-Fas antibody (CH-11). Flow cytometric analysis demonstrated that the differential Fas expression of human brain tumor cell lines partially correlated with levels of apoptosis through FIZ-shFasL. The upper limit of FIZ-shFasL for safe systemic administration to rat is estimated as below 2 microg/ml in plasma concentration. FIZ-shFasL could be applicable as a therapeutic agent for cancer.     

Maternal and fetal distribution of a phosphorothioate oligonucleotide in rats after intravenous infusion

BACKGROUND: Fetal uptake of an antisense oligonucleotide was evaluated after intravenous (i.v.) dosing of ISIS 2105, a 20-base phosphorothioate oligonucleotide, in timed-pregnant Sprague-Dawley rats. METHODS: To maximize the potential for fetal exposure, ISIS 2105 was administered as a 3-hr infusion at 6.6 mg/kg/hr with a total dose of 20 mg/kg, or as a continuous 7-day infusion at 0.35 mg/kg/hr with a total dose of 59 mg/kg. This dosing regime is higher than a patient would be expected to receive in the clinical use of oligonucleotides. Infusions were delivered through a jugular vein cannula by syringe pump on gestation day (GD) 19 (3-hr exposure) or by osmotic pumps implanted subcutaneously (s.c.) starting on GD 12 (7-day exposures). RESULTS: After a 3-hr infusion, maternal and fetal plasma concentrations of ISIS 2105 were >100 microg/ml and <0.07 microg/ml, respectively with a maternal fetal ratio of >1,000. Maternal regions of the placenta had twice the oligonucleotide concentration compared to fetal regions of the placenta (6 microg/g vs. 3 microg/g). After this acute exposure the concentrations in fetal kidney and liver were approximately 140- and 500-fold less than the maternal kidney and liver respectively. After 7-day infusion maternal plasma concentrations were 0.82 microg/ml and fetal concentrations were <0.22 microg/ml. By capillary gel electrophoresis (CGE) only the fetal liver consistently had quantifiable oligonucleotide concentrations (range=1.01-4.95 microg/g) compared to a mean concentration of 50.11+/-1.71 microg/g in the maternal liver a maternal to fetal ratio of approximately 10:50 after 7 days of infusion. CONCLUSIONS: There was a low level of transfer from dam to fetus, consistent with a slow equilibrium but the permeability of placenta to this 6 kDa polyanionic compound seemed to be limited even at supraclinical doses.     

Selenium in Australia: selenium status and biofortification of wheat for better health.

Selenium (Se) is an essential micronutrient for humans and animals, but is deficient in at least a billion people worldwide. Wheat (Triticum aestivum L.) is a major dietary source of Se. The largest survey to date of Se status of Australians found a mean plasma Se concentration of 103 microg/l in 288 Adelaide residents, just above the nutritional adequacy level. In the total sample analysed (six surveys from 1977 to 2002; n = 834), plasma Se was higher in males and increased with age. This study showed that many South Australians consume inadequate Se to maximise selenoenzyme expression and cancer protection, and indicated that levels had declined around 20% from the 1970s. No significant genotypic variability for grain Se concentration was observed in modern wheat cultivars, but the diploid wheat Aegilops tauschii L. and rye (Secale cereale L.) were higher. Grain Se concentrations ranged 5-720 microg/kg and it was apparent that this variation was determined mostly by available soil Se level. Field trials, along with glasshouse and growth chamber studies, were used to investigate agronomic biofortification of wheat. Se applied as sodium selenate at rates of 4-120 g Se/ha increased grain Se concentration progressively up to 133-fold when sprayed on soil at seeding and up to 20-fold when applied as a foliar spray after flowering. A threshold of toxicity of around 325 mg Se/kg in leaves of young wheat plants was observed, a level that would not normally be reached with Se fertilisation. On the other hand sulphur (S) applied at the low rate of 30 kg/ha at seeding reduced grain Se concentration by 16%. Agronomic biofortification could be used by food companies as a cost-effective method to produce high-Se wheat products that contain most Se in the desirable selenomethionine form. Further studies are needed to assess the functionality of high-Se wheat, for example short-term clinical trials that measure changes in genome stability, lipid peroxidation and immunocompetence. Increasing the Se content of wheat is a food systems strategy that could increase the Se intake of whole populations.     

Selenium supplementation on plasma glutathione peroxidase activity in patients with end-stage chronic renal failure

Patients with chronic renal failure (CRF) usually have a lower than healthy level of selenium (Se) in whole blood and plasma. Plasma glutathione peroxidase (GSH-Px) is synthesized mostly in the kidney. In CRF patients, activity of this enzyme is significantly reduced and its reduction increases with the progress of the disease. The aim of the study was to evaluate the effect of Se supplementation to CRF patients at various stages of the disease on Se concentration in blood components and on plasma GSH-Px activity. The study group comprised 53 CRF patients at various stages of the disease supplemented with Se (200 μg/d for 3 mo as Se-enriched yeast, containing about 70% l-selenomethionine [SeMet]). The control group consisted of 20 healthy subjects. The Se concentration in blood components was measured spectrofluorometrically with 2,3-diaminonaphthalene as a complexing reagent. GSH-Px activity in red cell hemolysates and plasma was assayed by the coupled method with tert-butyl hydroperoxide as a substrate. The Se concentration in whole blood and plasma of CRF patients is significantly lower as compared with healthy subjects, but similar at all stages of the disease. In the patients’ plasma, total protein and albumin levels are also significantly lower than in healthy subjects. Plasma GSH-Px activity in patients is extremely low, and contrary to Se concentration, it decreases linearly with the increasing stage of the illness. Se-supplied patients show an increased Se concentration in all blood components and at all disease stages, whereas plasma GSH-Px activity is enhanced only at the incipient stage of the disease. Se supply has no effect on plasma GSH-Px activity in uremic patients at the end stage of the disease. Total plasma protein and albumin levels did not change after Se supplementation. Our data seem to show that in patients with CRF lower total protein and albumin levels in plasma may be the chief cause of the low blood and plasma Se concentrations. GSH-Px activity decreases along with the kidney impairment. At the end stage of the disease, Se supplementation in the form of Se-enriched yeast has no effect on the increase in plasma GSH-Px activity.